From: Alessandro Carminati <[email protected]>
It is not uncommon for drivers or modules related to similar peripherals
to have symbols with the exact same name.
While this is not a problem for the kernel's binary itself, it becomes an
issue when attempting to trace or probe specific functions using
infrastructure like ftrace or kprobe.
The tracing subsystem relies on the `nm -n vmlinux` output, which provides
symbol information from the kernel's ELF binary. However, when multiple
symbols share the same name, the standard nm output does not differentiate
between them. This can lead to confusion and difficulty when trying to
probe the intended symbol.
~ # cat /proc/kallsyms | grep " name_show"
ffffffff8c4f76d0 t name_show
ffffffff8c9cccb0 t name_show
ffffffff8cb0ac20 t name_show
ffffffff8cc728c0 t name_show
ffffffff8ce0efd0 t name_show
ffffffff8ce126c0 t name_show
ffffffff8ce1dd20 t name_show
ffffffff8ce24e70 t name_show
ffffffff8d1104c0 t name_show
ffffffff8d1fe480 t name_show
**kas_alias** addresses this challenge by extending the symbol names with
unique suffixes during the kernel build process.
The newly created aliases for these duplicated symbols are unique names
that can be fed to the ftracefs interface. By doing so, it enables
previously unreachable symbols to be probed.
~ # cat /proc/kallsyms | grep " name_show"
ffffffff974f76d0 t name_show
ffffffff974f76d0 t name_show__alias__6340
ffffffff979cccb0 t name_show
ffffffff979cccb0 t name_show__alias__6341
ffffffff97b0ac20 t name_show
ffffffff97b0ac20 t name_show__alias__6342
ffffffff97c728c0 t name_show
ffffffff97c728c0 t name_show__alias__6343
ffffffff97e0efd0 t name_show
ffffffff97e0efd0 t name_show__alias__6344
ffffffff97e126c0 t name_show
ffffffff97e126c0 t name_show__alias__6345
ffffffff97e1dd20 t name_show
ffffffff97e1dd20 t name_show__alias__6346
ffffffff97e24e70 t name_show
ffffffff97e24e70 t name_show__alias__6347
ffffffff981104c0 t name_show
ffffffff981104c0 t name_show__alias__6348
ffffffff981fe480 t name_show
ffffffff981fe480 t name_show__alias__6349
~ # echo "p:kprobes/evnt1 name_show__alias__6349" \
> >/sys/kernel/tracing/kprobe_events
~ # cat /sys/kernel/tracing/kprobe_events
p:kprobes/evnt1 name_show__alias__6349
Changes from v1:
- Integrated changes requested by Masami to exclude symbols with prefixes
"_cfi" and "_pfx".
- Introduced a small framework to handle patterns that need to be excluded
from the alias production.
- Excluded other symbols using the framework.
- Introduced the ability to discriminate between text and data symbols.
- Added two new config symbols in this version: CONFIG_KALLSYMS_ALIAS_DATA,
which allows data for data, and CONFIG_KALLSYMS_ALIAS_DATA_ALL, which
excludes all filters and provides an alias for each duplicated symbol.
https://lore.kernel.org/all/[email protected]/
Changes from v2:
- Alias tags are created by querying DWARF information from the vmlinux.
- The filename + line number is normalized and appended to the original name.
- The tag begins with '@' to indicate the symbol source.
- Not a change, but worth mentioning, since the alias is added to the existing
list, the old duplicated name is preserved, and the livepatch way of dealing
with duplicates is maintained.
- Acknowledging the existence of scenarios where inlined functions declared in
header files may result in multiple copies due to compiler behavior, though
it is not actionable as it does not pose an operational issue.
- Highlighting a single exception where the same name refers to different
functions: the case of "compat_binfmt_elf.c," which directly includes
"binfmt_elf.c" producing identical function copies in two separate
modules.
sample from new v3
~ # cat /proc/kallsyms | grep gic_mask_irq
ffffd0b03c04dae4 t gic_mask_irq
ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
ffffd0b03c050960 t gic_mask_irq
ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
~ #
https://lore.kernel.org/all/[email protected]/
Signed-off-by: Alessandro Carminati (Red Hat) <[email protected]>
---
init/Kconfig | 36 ++++
scripts/Makefile | 4 +
scripts/kas_alias/Makefile | 4 +
scripts/kas_alias/a2l.c | 268 ++++++++++++++++++++++++++++
scripts/kas_alias/a2l.h | 32 ++++
scripts/kas_alias/duplicates_list.c | 70 ++++++++
scripts/kas_alias/duplicates_list.h | 15 ++
scripts/kas_alias/item_list.c | 230 ++++++++++++++++++++++++
scripts/kas_alias/item_list.h | 26 +++
scripts/kas_alias/kas_alias.c | 217 ++++++++++++++++++++++
scripts/link-vmlinux.sh | 11 +-
11 files changed, 910 insertions(+), 3 deletions(-)
create mode 100644 scripts/kas_alias/Makefile
create mode 100644 scripts/kas_alias/a2l.c
create mode 100644 scripts/kas_alias/a2l.h
create mode 100644 scripts/kas_alias/duplicates_list.c
create mode 100644 scripts/kas_alias/duplicates_list.h
create mode 100644 scripts/kas_alias/item_list.c
create mode 100644 scripts/kas_alias/item_list.h
create mode 100644 scripts/kas_alias/kas_alias.c
diff --git a/init/Kconfig b/init/Kconfig
index f7f65af4ee12..bc69fcd9cbc8 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1737,6 +1737,42 @@ config KALLSYMS_BASE_RELATIVE
time constants, and no relocation pass is required at runtime to fix
up the entries based on the runtime load address of the kernel.
+config KALLSYMS_ALIAS
+ bool "Produces alias for duplicated symbols" if EXPERT
+ depends on KALLSYMS && (DEBUG_INFO_DWARF4 || DEBUG_INFO_DWARF5)
+ help
+ It is not uncommon for drivers or modules related to similar
+ peripherals to have symbols with the exact same name.
+ While this is not a problem for the kernel's binary itself, it
+ becomes an issue when attempting to trace or probe specific
+ functions using infrastructure like ftrace or kprobe.
+
+ This option addresses this challenge by extending the symbol names
+ with unique suffixes during the kernel build process.
+ The newly created aliases for these duplicated symbols are unique
+ names that can be fed to the ftrace sysfs interface. By doing so, it
+ enables previously unreachable symbols to be probed.
+
+config CONFIG_KALLSYMS_ALIAS_DATA
+ bool "Produces alias also for data"
+ depends on KALLSYMS_ALIAS
+ help
+ Sometimes it can be useful to refer to data. In live patch scenarios,
+ you may find yourself needing to use symbols that are shared with
+ other functions. Since symbols face the same issue as functions, this
+ option allows you to create aliases for data as well.
+
+config CONFIG_KALLSYMS_ALIAS_DATA_ALL
+ bool "Removes all filter when producing data alias"
+ depends on CONFIG_KALLSYMS_ALIAS_DATA
+ help
+ When selecting data aliases, not all symbols are included in the set
+ This is because many symbols are unlikely to be used. If you choose
+ to have an alias for all data symbols, be aware that it will
+ significantly increase the size.
+
+ If unsure, say N.
+
# end of the "standard kernel features (expert users)" menu
# syscall, maps, verifier
diff --git a/scripts/Makefile b/scripts/Makefile
index 32b6ba722728..65fafe17cfe5 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -49,3 +49,7 @@ subdir-$(CONFIG_SECURITY_SELINUX) += selinux
# Let clean descend into subdirs
subdir- += basic dtc gdb kconfig mod
+
+# KALLSyms alias
+subdir-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
+
diff --git a/scripts/kas_alias/Makefile b/scripts/kas_alias/Makefile
new file mode 100644
index 000000000000..e1fde69232b4
--- /dev/null
+++ b/scripts/kas_alias/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+hostprogs-always-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
+
+kas_alias-objs := duplicates_list.o item_list.o kas_alias.o a2l.o
diff --git a/scripts/kas_alias/a2l.c b/scripts/kas_alias/a2l.c
new file mode 100644
index 000000000000..a9692ac30180
--- /dev/null
+++ b/scripts/kas_alias/a2l.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "a2l.h"
+
+int addr2line_pid = -1;
+int a2l_in[2];
+int a2l_out[2];
+char line[MAX_BUF];
+char vmlinux_path[MAX_BUF];
+char addr2line_cmd[MAX_CMD_LEN];
+FILE *a2l_stdin, *a2l_stdout;
+
+static char *normalize_path(const char *input_path, char *output_path)
+{
+ char *prev_token = NULL;
+ char *delimiter = "/";
+ char inbuf[MAX_BUF];
+ char *token;
+ char *pos;
+
+ memset(inbuf, 0, MAX_BUF);
+ *output_path = '\0';
+ strncpy(inbuf, input_path, MAX_BUF);
+ if (!input_path || !output_path || strlen(input_path) == 0)
+ return NULL;
+
+ token = strtok(inbuf, delimiter);
+ while (token) {
+ if (strcmp(token, "..") == 0 && prev_token) {
+ pos = strrchr(output_path, '/');
+ if (pos)
+ *pos = '\0';
+
+ } else if (strcmp(token, ".") != 0) {
+ strcat(output_path, "/");
+ strcat(output_path, token);
+ }
+
+ prev_token = token;
+ token = strtok(NULL, delimiter);
+ }
+
+ return output_path;
+}
+
+static void path_of(const char *full_path, char *path)
+{
+ const char *last_slash = strrchr(full_path, '/');
+ size_t path_length;
+ char cwd[MAX_BUF];
+
+ if (!last_slash) {
+ if (getcwd(cwd, sizeof(cwd)))
+ strcpy(path, cwd);
+ else
+ strcpy(path, ".");
+ } else {
+ path_length = last_slash - full_path;
+ strncpy(path, full_path, path_length);
+ path[path_length] = '\0';
+ }
+}
+
+static bool file_exists(const char *file_path)
+{
+ FILE *file;
+
+ file = fopen(file_path, "r");
+ if (file) {
+ fclose(file);
+ return true;
+ }
+ return false;
+}
+
+int addr2line_init(const char *cmd, const char *vmlinux)
+{
+ if ((!file_exists(cmd)) || (!file_exists(vmlinux))) {
+ printf("file not found\n");
+ return 0;
+ }
+
+ path_of(vmlinux, vmlinux_path);
+ if (pipe(a2l_in) == -1) {
+ printf("Failed to create pipe\n");
+ return 0;
+ }
+
+ if (pipe(a2l_out) == -1) {
+ printf("Failed to create pipe\n");
+ return 0;
+ }
+
+ addr2line_pid = fork();
+ if (addr2line_pid == -1) {
+ printf("Failed to fork process\n");
+ close(a2l_in[P_READ]);
+ close(a2l_in[P_WRITE]);
+ close(a2l_out[P_READ]);
+ close(a2l_out[P_WRITE]);
+ return 0;
+ }
+
+ if (addr2line_pid == 0) {
+ dup2(a2l_in[P_READ], 0);
+ dup2(a2l_out[P_WRITE], 1);
+ close(a2l_in[P_WRITE]);
+ close(a2l_out[P_READ]);
+
+ execlp(cmd, cmd, ADDR2LINE_ARGS, vmlinux, NULL);
+
+ printf("Failed to execute addr2line command\n");
+ exit(1);
+ } else {
+ close(a2l_in[P_READ]);
+ close(a2l_out[P_WRITE]);
+ }
+
+ a2l_stdin = fdopen(a2l_in[P_WRITE], "w");
+ if (!a2l_stdin) {
+ printf("Failed to open pipe a2l_in\n");
+ return 0;
+ }
+
+ a2l_stdout = fdopen(a2l_out[P_READ], "r");
+ if (!a2l_stdout) {
+ printf("Failed to open pipe a2l_out\n");
+ fclose(a2l_stdin);
+ return 0;
+ }
+
+ return 1;
+}
+
+const char *remove_subdir(const char *home, const char *f_path)
+{
+ int i = 0;
+
+ while (*(home + i) == *(f_path + i))
+ i++;
+
+ return (strlen(home) != i) ? NULL : f_path + i;
+}
+
+char *addr2line_get_lines(uint64_t address)
+{
+ char buf[MAX_BUF];
+
+ fprintf(a2l_stdin, "%08lx\n", address);
+ fflush(a2l_stdin);
+
+ if (!fgets(line, sizeof(line), a2l_stdout)) {
+ printf("Failed to read lines from addr2line\n");
+ return NULL;
+ }
+
+ if (!fgets(line, sizeof(line), a2l_stdout)) {
+ printf("Failed to read lines from addr2line\n");
+ return NULL;
+ }
+
+ line[strcspn(line, "\n")] = '\0';
+ strncpy(buf, line, MAX_BUF);
+ return normalize_path(buf, line);
+}
+
+int addr2line_cleanup(void)
+{
+ int status;
+
+ if (addr2line_pid != -1) {
+ kill(addr2line_pid, SIGKILL);
+ waitpid(addr2line_pid, &status, 0);
+ fclose(a2l_stdin);
+ fclose(a2l_stdout);
+ addr2line_pid = -1;
+ }
+
+ return 1;
+}
+
+static char *find_executable(const char *command)
+{
+ char *path_env = getenv("PATH");
+ char *executable_path;
+ char *path_copy;
+ char *path;
+ int n;
+
+ if (!path_env)
+ return NULL;
+
+ path_copy = strdup(path_env);
+ if (!path_copy)
+ return NULL;
+
+ path = strtok(path_copy, ":");
+ while (path) {
+ n = snprintf(0, 0, "%s/%s", path, command);
+ executable_path = (char *)malloc(n + 1);
+ snprintf(executable_path, n + 1, "%s/%s", path, command);
+ if (access(executable_path, X_OK) == 0) {
+ free(path_copy);
+ return executable_path;
+ }
+
+ path = strtok(NULL, ":");
+ free(executable_path);
+ executable_path = NULL;
+ }
+
+ free(path_copy);
+ if (executable_path)
+ free(executable_path);
+ return NULL;
+}
+
+const char *get_addr2line(int mode)
+{
+ char *buf = "";
+
+ switch (mode) {
+ case A2L_CROSS:
+ buf = getenv("CROSS_COMPILE");
+ memcpy(addr2line_cmd, buf, strlen(buf));
+ case A2L_DEFAULT:
+ memcpy(addr2line_cmd + strlen(buf), ADDR2LINE, strlen(ADDR2LINE));
+ buf = find_executable(addr2line_cmd);
+ if (buf) {
+ memcpy(addr2line_cmd, buf, strlen(buf));
+ free(buf);
+ }
+ return addr2line_cmd;
+ case A2L_LLVM:
+ default:
+ return NULL;
+ }
+}
+
+char *get_vmlinux(char *input)
+{
+ const char *match_string1 = ".syms";
+ const char *match_string2 = ".tmp_vmlinux.kallsyms";
+ char *result = NULL;
+ char *match_pos;
+
+ match_pos = strstr(input, match_string1);
+ if (!match_pos)
+ return NULL;
+
+ match_pos = strstr(input, match_string2);
+ if (!match_pos)
+ return NULL;
+
+ result = strdup(input);
+ match_pos = strstr(result, match_string1);
+ *match_pos = '\0';
+ return result;
+}
diff --git a/scripts/kas_alias/a2l.h b/scripts/kas_alias/a2l.h
new file mode 100644
index 000000000000..ca6419229dde
--- /dev/null
+++ b/scripts/kas_alias/a2l.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef A2L_H
+#define A2L_H
+#include <stdint.h>
+
+#define ADDR2LINE "addr2line"
+#define ADDR2LINE_ARGS "-fe"
+//#define VMLINUX "vmlinux"
+#define MAX_BUF 4096
+#define MAX_CMD_LEN 256
+#define P_READ 0
+#define P_WRITE 1
+#define A2L_DEFAULT 1
+#define A2L_CROSS 2
+#define A2L_LLVM 3
+#define A2L_MAKE_VALUE 2
+
+extern int addr2line_pid;
+extern int a2l_in[2];
+extern int a2l_out[2];
+extern char line[MAX_BUF];
+extern char vmlinux_path[MAX_BUF];
+extern char addr2line_cmd[MAX_CMD_LEN];
+
+int addr2line_init(const char *cmd, const char *vmlinux);
+char *addr2line_get_lines(uint64_t address);
+int addr2line_cleanup(void);
+const char *remove_subdir(const char *home, const char *f_path);
+const char *get_addr2line(int mode);
+char *get_vmlinux(char *input);
+
+#endif
diff --git a/scripts/kas_alias/duplicates_list.c b/scripts/kas_alias/duplicates_list.c
new file mode 100644
index 000000000000..e7a3d2917937
--- /dev/null
+++ b/scripts/kas_alias/duplicates_list.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "item_list.h"
+#include "duplicates_list.h"
+
+struct duplicate_item *find_duplicates(struct item *list)
+{
+ struct duplicate_item *current_duplicate = NULL;
+ struct duplicate_item *duplicates = NULL;
+ struct duplicate_item *new_duplicate;
+ struct item *current_item = list;
+ bool prev_was_duplicate = false;
+ struct item *prev_item = NULL;
+
+ while (current_item) {
+ if ((prev_item && (strcmp(current_item->symb_name, prev_item->symb_name) == 0)) ||
+ prev_was_duplicate) {
+ if (!duplicates) {
+ duplicates = malloc(sizeof(struct duplicate_item));
+ if (!duplicates)
+ return NULL;
+
+ duplicates->original_item = prev_item;
+ duplicates->next = NULL;
+ current_duplicate = duplicates;
+ } else {
+ new_duplicate = malloc(sizeof(struct duplicate_item));
+ if (!new_duplicate) {
+ free_duplicates(&duplicates);
+ return NULL;
+ }
+
+ new_duplicate->original_item = prev_item;
+ new_duplicate->next = NULL;
+ current_duplicate->next = new_duplicate;
+ current_duplicate = new_duplicate;
+
+ if ((strcmp(current_item->symb_name, prev_item->symb_name) != 0) &&
+ (prev_was_duplicate))
+ prev_was_duplicate = false;
+ else
+ prev_was_duplicate = true;
+ }
+ }
+
+ prev_item = current_item;
+ current_item = current_item->next;
+ }
+
+ return duplicates;
+}
+
+void free_duplicates(struct duplicate_item **duplicates)
+{
+ struct duplicate_item *duplicates_iterator = *duplicates;
+ struct duplicate_item *app;
+
+ while (duplicates_iterator) {
+ app = duplicates_iterator;
+ duplicates_iterator = duplicates_iterator->next;
+ free(app);
+ }
+
+ *duplicates = NULL;
+}
diff --git a/scripts/kas_alias/duplicates_list.h b/scripts/kas_alias/duplicates_list.h
new file mode 100644
index 000000000000..76aa73e584bc
--- /dev/null
+++ b/scripts/kas_alias/duplicates_list.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef DUPLICATES_LIST_H
+#define DUPLICATES_LIST_H
+
+#include "item_list.h"
+
+struct duplicate_item {
+ struct item *original_item;
+ struct duplicate_item *next;
+};
+
+struct duplicate_item *find_duplicates(struct item *list);
+void free_duplicates(struct duplicate_item **duplicates);
+
+#endif
diff --git a/scripts/kas_alias/item_list.c b/scripts/kas_alias/item_list.c
new file mode 100644
index 000000000000..48f2e525592a
--- /dev/null
+++ b/scripts/kas_alias/item_list.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdbool.h>
+#include <assert.h>
+#include "item_list.h"
+
+#define CHECK_ORDER_BY_ADDRESS(sort_by, current, temp, op) \
+ ((sort_by) == BY_ADDRESS && (current)->addr op (temp)->addr)
+#define CHECK_ORDER_BY_NAME(sort_by, current, temp, op) \
+ ((sort_by) == BY_NAME && strcmp((current)->symb_name, (temp)->symb_name) op 0)
+
+struct item *list_index[96] = {0};
+
+void build_index(struct item *list)
+{
+ char current_first_letter = ' ';
+ struct item *current = list;
+
+ while (current) {
+ if (current->symb_name[0] != current_first_letter) {
+ current_first_letter = current->symb_name[0];
+ list_index[current_first_letter - 32] = current;
+ }
+ current = current->next;
+ }
+}
+
+struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr)
+{
+ struct item *new_item;
+ struct item *current;
+
+ new_item = malloc(sizeof(struct item));
+ if (!new_item)
+ return NULL;
+
+ strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
+ new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
+ new_item->addr = addr;
+ new_item->stype = stype;
+ new_item->next = NULL;
+
+ if (!(*list)) {
+ *list = new_item;
+ } else {
+ current = *list;
+ while (current->next)
+ current = current->next;
+
+ current->next = new_item;
+ }
+ return new_item;
+}
+
+void sort_list(struct item **list, int sort_by)
+{
+ struct item *current = *list;
+ struct item *sorted = NULL;
+ struct item *next_item;
+ struct item *temp;
+
+ if (!(*list) || !((*list)->next))
+ return;
+
+ while (current) {
+ next_item = current->next;
+ if (!sorted ||
+ (CHECK_ORDER_BY_ADDRESS(sort_by, current, sorted, <) ||
+ CHECK_ORDER_BY_NAME(sort_by, current, sorted, >=))) {
+ current->next = sorted;
+ sorted = current;
+ } else {
+ temp = sorted;
+ while (temp->next &&
+ (CHECK_ORDER_BY_ADDRESS(sort_by, current, temp->next, >=) ||
+ CHECK_ORDER_BY_NAME(sort_by, current, temp->next, >=)))
+ temp = temp->next;
+
+ current->next = temp->next;
+ temp->next = current;
+ }
+ current = next_item;
+ }
+
+ *list = sorted;
+}
+
+struct item *merge(struct item *left, struct item *right, int sort_by)
+{
+ struct item *current = NULL;
+ struct item *result = NULL;
+
+ if (!left)
+ return right;
+ if (!right)
+ return left;
+
+ if (sort_by == BY_NAME) {
+ if (strcmp(left->symb_name, right->symb_name) <= 0) {
+ result = left;
+ left = left->next;
+ } else {
+ result = right;
+ right = right->next;
+ }
+ } else {
+ if (sort_by == BY_ADDRESS) {
+ if (left->addr <= right->addr) {
+ result = left;
+ left = left->next;
+ } else {
+ result = right;
+ right = right->next;
+ }
+ }
+ }
+
+ current = result;
+
+ while (left && right) {
+ if (sort_by == BY_NAME) {
+ if (strcmp(left->symb_name, right->symb_name) <= 0) {
+ current->next = left;
+ left = left->next;
+ } else {
+ current->next = right;
+ right = right->next;
+ }
+ } else {
+ if (sort_by == BY_ADDRESS) {
+ if (left->addr <= right->addr) {
+ current->next = left;
+ left = left->next;
+ } else {
+ current->next = right;
+ right = right->next;
+ }
+ }
+ }
+
+ current = current->next;
+ }
+
+ if (left) {
+ current->next = left;
+ } else {
+ if (right)
+ current->next = right;
+ }
+
+ return result;
+}
+
+struct item *merge_sort(struct item *head, int sort_by)
+{
+ struct item *right;
+ struct item *slow;
+ struct item *fast;
+ struct item *left;
+
+ if (!head || !head->next)
+ return head;
+
+ slow = head;
+ fast = head->next;
+
+ while (fast && fast->next) {
+ slow = slow->next;
+ fast = fast->next->next;
+ }
+
+ left = head;
+ right = slow->next;
+ slow->next = NULL;
+
+ left = merge_sort(left, sort_by);
+ right = merge_sort(right, sort_by);
+
+ return merge(left, right, sort_by);
+}
+
+void sort_list_m(struct item **head, int sort_by)
+{
+ if (!(*head) || !((*head)->next))
+ return;
+
+ *head = merge_sort(*head, sort_by);
+}
+
+int insert_after(struct item *list, const uint64_t search_addr,
+ const char *name, uint64_t addr, char stype)
+{
+ struct item *new_item;
+ struct item *current;
+ int ret = 0;
+
+ current = (list_index[name[0] - 32]) ? list_index[name[0] - 32] : list;
+ while (current) {
+ if (current->addr == search_addr) {
+ new_item = malloc(sizeof(struct item));
+ if (!new_item)
+ return ret;
+ strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
+ new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
+ new_item->addr = addr;
+ new_item->stype = stype;
+ new_item->next = current->next;
+ current->next = new_item;
+ ret = 1;
+ break;
+ }
+ current = current->next;
+ }
+ return ret;
+}
+
+void free_items(struct item **head)
+{
+ struct item *app, *item_iterator = *head;
+
+ while (item_iterator) {
+ app = item_iterator;
+ item_iterator = item_iterator->next;
+ free(app);
+ }
+ *head = NULL;
+}
diff --git a/scripts/kas_alias/item_list.h b/scripts/kas_alias/item_list.h
new file mode 100644
index 000000000000..b4891cb088ee
--- /dev/null
+++ b/scripts/kas_alias/item_list.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef ITEM_LIST_H
+#define ITEM_LIST_H
+#include <stdint.h>
+
+#define MAX_NAME_SIZE 256
+#define BY_ADDRESS 1
+#define BY_NAME 2
+
+struct item {
+ char symb_name[MAX_NAME_SIZE];
+ uint64_t addr;
+ char stype;
+ struct item *next;
+};
+
+void build_index(struct item *list);
+struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr);
+void sort_list(struct item **list, int sort_by);
+struct item *merge(struct item *left, struct item *right, int sort_by);
+struct item *merge_sort(struct item *head, int sort_by);
+void sort_list_m(struct item **head, int sort_by);
+int insert_after(struct item *list, const uint64_t search_addr,
+ const char *name, uint64_t addr, char stype);
+void free_items(struct item **head);
+#endif
diff --git a/scripts/kas_alias/kas_alias.c b/scripts/kas_alias/kas_alias.c
new file mode 100644
index 000000000000..532aeb39f851
--- /dev/null
+++ b/scripts/kas_alias/kas_alias.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <regex.h>
+
+#include "item_list.h"
+#include "duplicates_list.h"
+#include "a2l.h"
+
+#define SYMB_IS_TEXT(s) ((((s)->stype) == 't') || (((s)->stype) == 'T'))
+#define SYMB_IS_DATA(s) ((((s)->stype) == 'b') || (((s)->stype) == 'B') || \
+ (((s)->stype) == 'd') || (((s)->stype) == 'D') || \
+ (((s)->stype) == 'r') || (((s)->stype) == 'R'))
+#ifdef CONFIG_KALLSYMS_ALIAS_DATA
+#define SYMB_NEEDS_ALIAS(s) (SYMB_IS_TEXT(s) || SYMB_IS_DATA(s))
+#else
+#define SYMB_NEEDS_ALIAS(s) SYMB_IS_TEXT(s)
+#endif
+#define FNOMATCH 0
+#define FMATCH 1
+#define EREGEX 2
+
+const char *ignore_regex[] = {
+ "^__cfi_.*$", // __cfi_ preamble
+#ifndef CONFIG_KALLSYMS_ALIAS_DATA_ALL
+ "^_*TRACE_SYSTEM.*$",
+ "^__already_done\\.[0-9]+$", // Call a function once data
+ "^___tp_str\\.[0-9]+$",
+ "^___done\\.[0-9]+$",
+ "^__print_once\\.[0-9]+$",
+ "^_rs\\.[0-9]+$",
+ "^__compound_literal\\.[0-9]+$",
+ "^___once_key\\.[0-9]+$",
+ "^__func__\\.[0-9]+$",
+ "^__msg\\.[0-9]+$",
+ "^CSWTCH\\.[0-9]+$",
+ "^__flags\\.[0-9]+$",
+ "^__wkey.*$",
+ "^__mkey.*$",
+ "^__key.*$",
+#endif
+ "^__pfx_.*$" // NOP-padding
+};
+
+int suffix_serial;
+
+static inline void verbose_msg(bool verbose, const char *fmt, ...)
+{
+ va_list args;
+
+ va_start(args, fmt);
+ if (verbose)
+ printf(fmt, args);
+
+ va_end(args);
+}
+
+static void create_suffix(const char *name, char *output_suffix)
+{
+ sprintf(output_suffix, "%s__alias__%d", name, suffix_serial++);
+}
+
+static void create_file_suffix(const char *name, uint64_t address, char *output_suffix, char *cwd)
+{
+ const char *f_path;
+ char *buf;
+ int i = 0;
+
+ buf = addr2line_get_lines(address);
+ f_path = remove_subdir(cwd, buf);
+ if (f_path) {
+ sprintf(output_suffix, "%s@%s", name, f_path);
+ while (*(output_suffix + i) != '\0') {
+ switch (*(output_suffix + i)) {
+ case '/':
+ case ':':
+ case '.':
+ *(output_suffix + i) = '_';
+ break;
+ default:
+ }
+ i++;
+ }
+ } else {
+ create_suffix(name, output_suffix);
+ }
+}
+
+static int filter_symbols(char *symbol, const char **ignore_list, int regex_no)
+{
+ regex_t regex;
+ int res, i;
+
+ for (i = 0; i < regex_no; i++) {
+ res = regcomp(®ex, ignore_list[i], REG_EXTENDED);
+ if (res)
+ return -EREGEX;
+
+ res = regexec(®ex, symbol, 0, NULL, 0);
+ regfree(®ex);
+ switch (res) {
+ case 0:
+ return FMATCH;
+ case REG_NOMATCH:
+ break;
+ default:
+ return -EREGEX;
+ }
+ }
+
+ return FNOMATCH;
+}
+
+int main(int argc, char *argv[])
+{
+ char t, sym_name[MAX_NAME_SIZE], new_name[MAX_NAME_SIZE + 15];
+ struct duplicate_item *duplicate_iterator;
+ struct duplicate_item *duplicate;
+ struct item *head = {NULL};
+ bool need_2_process = true;
+ struct item *last = {NULL};
+ struct item *current;
+ int verbose_mode = 0;
+ uint64_t address;
+ FILE *fp;
+ int res;
+
+ if (argc < 2 || argc > 3) {
+ printf("Usage: %s <nmfile> [-verbose]\n", argv[0]);
+ return 1;
+ }
+
+ if (argc == 3 && strcmp(argv[2], "-verbose") == 0)
+ verbose_mode = 1;
+
+ verbose_msg(verbose_mode, "Scanning nm data(%s)\n", argv[1]);
+
+ fp = fopen(argv[1], "r");
+ if (!fp) {
+ printf("Can't open input file.\n");
+ return 1;
+ }
+
+ if (!addr2line_init(get_addr2line(A2L_DEFAULT), get_vmlinux(argv[1])))
+ return 1;
+
+ while (fscanf(fp, "%lx %c %99s\n", &address, &t, sym_name) == 3) {
+ if (strstr(sym_name, "@_")) {
+ if (verbose_mode && need_2_process)
+ printf("Already processed\n");
+ need_2_process = false;
+ }
+ last = add_item(&last, sym_name, t, address);
+ if (!last) {
+ printf("Error in allocate memory\n");
+ free_items(&head);
+ return 1;
+ }
+
+ if (!head)
+ head = last;
+ }
+
+ fclose(fp);
+
+ if (need_2_process) {
+ verbose_msg(verbose_mode, "Sorting nm data\n");
+ sort_list_m(&head, BY_NAME);
+ verbose_msg(verbose_mode, "Scanning nm data for duplicates\n");
+ duplicate = find_duplicates(head);
+ if (!duplicate) {
+ printf("Error in duplicates list\n");
+ return 1;
+ }
+
+ verbose_msg(verbose_mode, "Applying suffixes\n");
+ build_index(head);
+ duplicate_iterator = duplicate;
+ while (duplicate_iterator) {
+ res = filter_symbols(duplicate_iterator->original_item->symb_name,
+ ignore_regex, sizeof(ignore_regex) /
+ sizeof(ignore_regex[0]));
+ if (res != FMATCH &&
+ SYMB_NEEDS_ALIAS(duplicate_iterator->original_item)) {
+ if (res < 0)
+ return 1;
+
+ create_file_suffix(duplicate_iterator->original_item->symb_name,
+ duplicate_iterator->original_item->addr,
+ new_name, vmlinux_path);
+ if (!insert_after(head, duplicate_iterator->original_item->addr,
+ new_name, duplicate_iterator->original_item->addr,
+ duplicate_iterator->original_item->stype))
+ return 1;
+ }
+
+ duplicate_iterator = duplicate_iterator->next;
+ }
+
+ sort_list_m(&head, BY_ADDRESS);
+ }
+ current = head;
+ while (current) {
+ printf("%08lx %c %s\n", current->addr, current->stype, current->symb_name);
+ current = current->next;
+ }
+
+ free_items(&head);
+ free_duplicates(&duplicate);
+ addr2line_cleanup();
+ return 0;
+}
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index a432b171be82..cacf60b597ce 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -89,8 +89,9 @@ vmlinux_link()
ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
- # The kallsyms linking does not need debug symbols included.
- if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
+ # The kallsyms linking does not need debug symbols included, unless the KALLSYMS_ALIAS.
+ if [ ! is_enabled CONFIG_KALLSYMS_ALIAS ] && \
+ [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
ldflags="${ldflags} ${wl}--strip-debug"
fi
@@ -161,7 +162,11 @@ kallsyms()
fi
info KSYMS ${2}
- scripts/kallsyms ${kallsymopt} ${1} > ${2}
+ if is_enabled CONFIG_KALLSYMS_ALIAS; then
+ ALIAS=".alias"
+ scripts/kas_alias/kas_alias ${1} >${1}${ALIAS}
+ fi
+ scripts/kallsyms ${kallsymopt} ${1}${ALIAS} > ${2}
}
# Perform one step in kallsyms generation, including temporary linking of
--
2.34.1
Hi.
Le lundi 28 ao?t 2023, 10:04:23 CEST Alessandro Carminati (Red Hat) a ?crit :
> From: Alessandro Carminati <[email protected]>
>
> It is not uncommon for drivers or modules related to similar peripherals
> to have symbols with the exact same name.
> While this is not a problem for the kernel's binary itself, it becomes an
> issue when attempting to trace or probe specific functions using
> infrastructure like ftrace or kprobe.
Thank you for the patch!
I tested it and it works fine:
root@vm-amd64:~# grep -m 6 ' name_show' /proc/kallsyms
ffffffff81108330 t name_show
ffffffff81108330 t name_show@_kernel_irq_irqdesc_c_264
ffffffff816d2dd0 t name_show
ffffffff816d2dd0 t name_show@_drivers_pnp_card_c_186
ffffffff81814990 t name_show
ffffffff81814990 t name_show@_drivers_gpu_drm_i915_gt_sysfs_engines_c_26
On the paper, it combines well with my other patch forbidding tracing non
unique symbols.
I will nonetheless need to try yours on top of mine and I will let you know
the result, even though everything should go well.
Regarding the code itself, from my review your implementation is good.
I was just wondering if we cannot avoid the first sort BY_NAME by modifying
find_duplicates() and the returned structured, but the index you are using
later should reduce the loopthrough time and compensate the first sort.
I have some specific comments but they are mainly nits:
> The tracing subsystem relies on the `nm -n vmlinux` output, which provides
> symbol information from the kernel's ELF binary. However, when multiple
> symbols share the same name, the standard nm output does not differentiate
> between them. This can lead to confusion and difficulty when trying to
> probe the intended symbol.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff8c4f76d0 t name_show
> ffffffff8c9cccb0 t name_show
> ffffffff8cb0ac20 t name_show
> ffffffff8cc728c0 t name_show
> ffffffff8ce0efd0 t name_show
> ffffffff8ce126c0 t name_show
> ffffffff8ce1dd20 t name_show
> ffffffff8ce24e70 t name_show
> ffffffff8d1104c0 t name_show
> ffffffff8d1fe480 t name_show
>
> **kas_alias** addresses this challenge by extending the symbol names with
> unique suffixes during the kernel build process.
> The newly created aliases for these duplicated symbols are unique names
> that can be fed to the ftracefs interface. By doing so, it enables
> previously unreachable symbols to be probed.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff974f76d0 t name_show
> ffffffff974f76d0 t name_show__alias__6340
This output is outdated.
This is not a big problem but it would be better with the updated one as the
"@_file_line" is better.
> ffffffff979cccb0 t name_show
> ffffffff979cccb0 t name_show__alias__6341
> ffffffff97b0ac20 t name_show
> ffffffff97b0ac20 t name_show__alias__6342
> ffffffff97c728c0 t name_show
> ffffffff97c728c0 t name_show__alias__6343
> ffffffff97e0efd0 t name_show
> ffffffff97e0efd0 t name_show__alias__6344
> ffffffff97e126c0 t name_show
> ffffffff97e126c0 t name_show__alias__6345
> ffffffff97e1dd20 t name_show
> ffffffff97e1dd20 t name_show__alias__6346
> ffffffff97e24e70 t name_show
> ffffffff97e24e70 t name_show__alias__6347
> ffffffff981104c0 t name_show
> ffffffff981104c0 t name_show__alias__6348
> ffffffff981fe480 t name_show
> ffffffff981fe480 t name_show__alias__6349
> ~ # echo "p:kprobes/evnt1 name_show__alias__6349" \
>
> > >/sys/kernel/tracing/kprobe_events
>
> ~ # cat /sys/kernel/tracing/kprobe_events
> p:kprobes/evnt1 name_show__alias__6349
>
> Changes from v1:
> - Integrated changes requested by Masami to exclude symbols with prefixes
> "_cfi" and "_pfx".
> - Introduced a small framework to handle patterns that need to be excluded
> from the alias production.
> - Excluded other symbols using the framework.
> - Introduced the ability to discriminate between text and data symbols.
> - Added two new config symbols in this version: CONFIG_KALLSYMS_ALIAS_DATA,
> which allows data for data, and CONFIG_KALLSYMS_ALIAS_DATA_ALL, which
> excludes all filters and provides an alias for each duplicated symbol.
>
> https://lore.kernel.org/all/20230711151925.1092080-1-alessandro.carminati@gm
> ail.com/
>
> Changes from v2:
> - Alias tags are created by querying DWARF information from the vmlinux.
> - The filename + line number is normalized and appended to the original
> name. - The tag begins with '@' to indicate the symbol source.
> - Not a change, but worth mentioning, since the alias is added to the
> existing list, the old duplicated name is preserved, and the livepatch way
> of dealing with duplicates is maintained.
> - Acknowledging the existence of scenarios where inlined functions declared
> in header files may result in multiple copies due to compiler behavior,
> though it is not actionable as it does not pose an operational issue.
> - Highlighting a single exception where the same name refers to different
> functions: the case of "compat_binfmt_elf.c," which directly includes
> "binfmt_elf.c" producing identical function copies in two separate
> modules.
>
> sample from new v3
>
> ~ # cat /proc/kallsyms | grep gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> ffffd0b03c050960 t gic_mask_irq
> ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
> ~ #
>
> https://lore.kernel.org/all/20230714150326.1152359-1-alessandro.carminati@gm
> ail.com/
>
> Signed-off-by: Alessandro Carminati (Red Hat)
> <[email protected]> ---
> init/Kconfig | 36 ++++
> scripts/Makefile | 4 +
> scripts/kas_alias/Makefile | 4 +
> scripts/kas_alias/a2l.c | 268 ++++++++++++++++++++++++++++
> scripts/kas_alias/a2l.h | 32 ++++
> scripts/kas_alias/duplicates_list.c | 70 ++++++++
> scripts/kas_alias/duplicates_list.h | 15 ++
> scripts/kas_alias/item_list.c | 230 ++++++++++++++++++++++++
> scripts/kas_alias/item_list.h | 26 +++
> scripts/kas_alias/kas_alias.c | 217 ++++++++++++++++++++++
> scripts/link-vmlinux.sh | 11 +-
> 11 files changed, 910 insertions(+), 3 deletions(-)
> create mode 100644 scripts/kas_alias/Makefile
> create mode 100644 scripts/kas_alias/a2l.c
> create mode 100644 scripts/kas_alias/a2l.h
> create mode 100644 scripts/kas_alias/duplicates_list.c
> create mode 100644 scripts/kas_alias/duplicates_list.h
> create mode 100644 scripts/kas_alias/item_list.c
> create mode 100644 scripts/kas_alias/item_list.h
> create mode 100644 scripts/kas_alias/kas_alias.c
>
> diff --git a/init/Kconfig b/init/Kconfig
> index f7f65af4ee12..bc69fcd9cbc8 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1737,6 +1737,42 @@ config KALLSYMS_BASE_RELATIVE
> time constants, and no relocation pass is required at runtime to fix
> up the entries based on the runtime load address of the kernel.
>
> +config KALLSYMS_ALIAS
> + bool "Produces alias for duplicated symbols" if EXPERT
> + depends on KALLSYMS && (DEBUG_INFO_DWARF4 || DEBUG_INFO_DWARF5)
> + help
> + It is not uncommon for drivers or modules related to similar
> + peripherals to have symbols with the exact same name.
> + While this is not a problem for the kernel's binary itself, it
> + becomes an issue when attempting to trace or probe specific
> + functions using infrastructure like ftrace or kprobe.
> +
> + This option addresses this challenge by extending the symbol names
> + with unique suffixes during the kernel build process.
> + The newly created aliases for these duplicated symbols are unique
> + names that can be fed to the ftrace sysfs interface. By doing so, it
> + enables previously unreachable symbols to be probed.
> +
> +config CONFIG_KALLSYMS_ALIAS_DATA
> + bool "Produces alias also for data"
> + depends on KALLSYMS_ALIAS
> + help
> + Sometimes it can be useful to refer to data. In live patch
scenarios,
> + you may find yourself needing to use symbols that are shared with
> + other functions. Since symbols face the same issue as functions,
this
> + option allows you to create aliases for data as well.
> +
> +config CONFIG_KALLSYMS_ALIAS_DATA_ALL
> + bool "Removes all filter when producing data alias"
> + depends on CONFIG_KALLSYMS_ALIAS_DATA
> + help
> + When selecting data aliases, not all symbols are included in the set
> + This is because many symbols are unlikely to be used. If you choose
> + to have an alias for all data symbols, be aware that it will
> + significantly increase the size.
> +
> + If unsure, say N.
> +
> # end of the "standard kernel features (expert users)" menu
>
> # syscall, maps, verifier
> diff --git a/scripts/Makefile b/scripts/Makefile
> index 32b6ba722728..65fafe17cfe5 100644
> --- a/scripts/Makefile
> +++ b/scripts/Makefile
> @@ -49,3 +49,7 @@ subdir-$(CONFIG_SECURITY_SELINUX) += selinux
>
> # Let clean descend into subdirs
> subdir- += basic dtc gdb kconfig mod
> +
> +# KALLSyms alias
> +subdir-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
> +
> diff --git a/scripts/kas_alias/Makefile b/scripts/kas_alias/Makefile
> new file mode 100644
> index 000000000000..e1fde69232b4
> --- /dev/null
> +++ b/scripts/kas_alias/Makefile
> @@ -0,0 +1,4 @@
> +# SPDX-License-Identifier: GPL-2.0
> +hostprogs-always-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
> +
> +kas_alias-objs := duplicates_list.o item_list.o kas_alias.o a2l.o
> diff --git a/scripts/kas_alias/a2l.c b/scripts/kas_alias/a2l.c
> new file mode 100644
> index 000000000000..a9692ac30180
> --- /dev/null
> +++ b/scripts/kas_alias/a2l.c
> @@ -0,0 +1,268 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <string.h>
> +#include <stdint.h>
> +#include <stdbool.h>
> +
> +#include "a2l.h"
> +
> +int addr2line_pid = -1;
> +int a2l_in[2];
> +int a2l_out[2];
> +char line[MAX_BUF];
> +char vmlinux_path[MAX_BUF];
> +char addr2line_cmd[MAX_CMD_LEN];
> +FILE *a2l_stdin, *a2l_stdout;
> +
> +static char *normalize_path(const char *input_path, char *output_path)
> +{
> + char *prev_token = NULL;
> + char *delimiter = "/";
> + char inbuf[MAX_BUF];
Rather than using memset below you can initialize it like this above:
char inbuf[MAX_BUF] = {0};
> + char *token;
> + char *pos;
> +
> + memset(inbuf, 0, MAX_BUF);
> + *output_path = '\0';
> + strncpy(inbuf, input_path, MAX_BUF);
> + if (!input_path || !output_path || strlen(input_path) == 0)
> + return NULL;
> +
> + token = strtok(inbuf, delimiter);
> + while (token) {
> + if (strcmp(token, "..") == 0 && prev_token) {
> + pos = strrchr(output_path, '/');
> + if (pos)
> + *pos = '\0';
> +
> + } else if (strcmp(token, ".") != 0) {
> + strcat(output_path, "/");
> + strcat(output_path, token);
> + }
> +
> + prev_token = token;
> + token = strtok(NULL, delimiter);
> + }
> +
> + return output_path;
> +}
> +
> +static void path_of(const char *full_path, char *path)
> +{
> + const char *last_slash = strrchr(full_path, '/');
> + size_t path_length;
> + char cwd[MAX_BUF];
> +
> + if (!last_slash) {
> + if (getcwd(cwd, sizeof(cwd)))
> + strcpy(path, cwd);
> + else
> + strcpy(path, ".");
> + } else {
> + path_length = last_slash - full_path;
> + strncpy(path, full_path, path_length);
> + path[path_length] = '\0';
> + }
> +}
> +
> +static bool file_exists(const char *file_path)
> +{
> + FILE *file;
> +
> + file = fopen(file_path, "r");
> + if (file) {
> + fclose(file);
> + return true;
> + }
> + return false;
> +}
> +
> +int addr2line_init(const char *cmd, const char *vmlinux)
> +{
> + if ((!file_exists(cmd)) || (!file_exists(vmlinux))) {
> + printf("file not found\n");
> + return 0;
> + }
> +
> + path_of(vmlinux, vmlinux_path);
> + if (pipe(a2l_in) == -1) {
> + printf("Failed to create pipe\n");
> + return 0;
> + }
> +
> + if (pipe(a2l_out) == -1) {
> + printf("Failed to create pipe\n");
> + return 0;
> + }
> +
> + addr2line_pid = fork();
> + if (addr2line_pid == -1) {
> + printf("Failed to fork process\n");
> + close(a2l_in[P_READ]);
> + close(a2l_in[P_WRITE]);
> + close(a2l_out[P_READ]);
> + close(a2l_out[P_WRITE]);
> + return 0;
> + }
> +
> + if (addr2line_pid == 0) {
> + dup2(a2l_in[P_READ], 0);
> + dup2(a2l_out[P_WRITE], 1);
> + close(a2l_in[P_WRITE]);
> + close(a2l_out[P_READ]);
> +
> + execlp(cmd, cmd, ADDR2LINE_ARGS, vmlinux, NULL);
> +
> + printf("Failed to execute addr2line command\n");
> + exit(1);
> + } else {
> + close(a2l_in[P_READ]);
> + close(a2l_out[P_WRITE]);
> + }
> +
> + a2l_stdin = fdopen(a2l_in[P_WRITE], "w");
> + if (!a2l_stdin) {
> + printf("Failed to open pipe a2l_in\n");
> + return 0;
> + }
> +
> + a2l_stdout = fdopen(a2l_out[P_READ], "r");
> + if (!a2l_stdout) {
> + printf("Failed to open pipe a2l_out\n");
> + fclose(a2l_stdin);
> + return 0;
> + }
> +
> + return 1;
> +}
> +
> +const char *remove_subdir(const char *home, const char *f_path)
> +{
> + int i = 0;
> +
> + while (*(home + i) == *(f_path + i))
Using home[i] and f_path[i] should do the trick too.
> + i++;
> +
> + return (strlen(home) != i) ? NULL : f_path + i;
> +}
> +
> +char *addr2line_get_lines(uint64_t address)
> +{
> + char buf[MAX_BUF];
> +
> + fprintf(a2l_stdin, "%08lx\n", address);
> + fflush(a2l_stdin);
> +
> + if (!fgets(line, sizeof(line), a2l_stdout)) {
> + printf("Failed to read lines from addr2line\n");
> + return NULL;
> + }
> +
> + if (!fgets(line, sizeof(line), a2l_stdout)) {
> + printf("Failed to read lines from addr2line\n");
> + return NULL;
> + }
> + line[strcspn(line, "\n")] = '\0';
> + strncpy(buf, line, MAX_BUF);
> + return normalize_path(buf, line);
> +}
> +
> +int addr2line_cleanup(void)
> +{
> + int status;
> +
> + if (addr2line_pid != -1) {
> + kill(addr2line_pid, SIGKILL);
> + waitpid(addr2line_pid, &status, 0);
> + fclose(a2l_stdin);
> + fclose(a2l_stdout);
> + addr2line_pid = -1;
> + }
> +
> + return 1;
> +}
> +
> +static char *find_executable(const char *command)
Nice function, I would rather have tried to execve() the command.
> +{
> + char *path_env = getenv("PATH");
> + char *executable_path;
> + char *path_copy;
> + char *path;
> + int n;
> +
> + if (!path_env)
> + return NULL;
> +
> + path_copy = strdup(path_env);
> + if (!path_copy)
> + return NULL;
> +
> + path = strtok(path_copy, ":");
> + while (path) {
> + n = snprintf(0, 0, "%s/%s", path, command);
> + executable_path = (char *)malloc(n + 1);
> + snprintf(executable_path, n + 1, "%s/%s", path, command);
> + if (access(executable_path, X_OK) == 0) {
> + free(path_copy);
> + return executable_path;
> + }
> +
> + path = strtok(NULL, ":");
> + free(executable_path);
> + executable_path = NULL;
> + }
> +
> + free(path_copy);
> + if (executable_path)
> + free(executable_path);
If you arrive here, executable_path should be NULL, right?
> + return NULL;
> +}
> +
> +const char *get_addr2line(int mode)
> +{
> + char *buf = "";
> +
> + switch (mode) {
> + case A2L_CROSS:
> + buf = getenv("CROSS_COMPILE");
> + memcpy(addr2line_cmd, buf, strlen(buf));
> + case A2L_DEFAULT:
> + memcpy(addr2line_cmd + strlen(buf), ADDR2LINE,
strlen(ADDR2LINE));
> + buf = find_executable(addr2line_cmd);
> + if (buf) {
> + memcpy(addr2line_cmd, buf, strlen(buf));
> + free(buf);
> + }
> + return addr2line_cmd;
> + case A2L_LLVM:
> + default:
> + return NULL;
> + }
> +}
> +
> +char *get_vmlinux(char *input)
> +{
> + const char *match_string1 = ".syms";
> + const char *match_string2 = ".tmp_vmlinux.kallsyms";
> + char *result = NULL;
> + char *match_pos;
> +
> + match_pos = strstr(input, match_string1);
> + if (!match_pos)
> + return NULL;
> +
> + match_pos = strstr(input, match_string2);
> + if (!match_pos)
> + return NULL;
> +
> + result = strdup(input);
> + match_pos = strstr(result, match_string1);
> + *match_pos = '\0';
> + return result;
> +}
> diff --git a/scripts/kas_alias/a2l.h b/scripts/kas_alias/a2l.h
> new file mode 100644
> index 000000000000..ca6419229dde
> --- /dev/null
> +++ b/scripts/kas_alias/a2l.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef A2L_H
> +#define A2L_H
> +#include <stdint.h>
> +
> +#define ADDR2LINE "addr2line"
> +#define ADDR2LINE_ARGS "-fe"
> +//#define VMLINUX "vmlinux"
> +#define MAX_BUF 4096
> +#define MAX_CMD_LEN 256
> +#define P_READ 0
> +#define P_WRITE 1
> +#define A2L_DEFAULT 1
> +#define A2L_CROSS 2
> +#define A2L_LLVM 3
> +#define A2L_MAKE_VALUE 2
> +
> +extern int addr2line_pid;
> +extern int a2l_in[2];
> +extern int a2l_out[2];
> +extern char line[MAX_BUF];
> +extern char vmlinux_path[MAX_BUF];
> +extern char addr2line_cmd[MAX_CMD_LEN];
> +
> +int addr2line_init(const char *cmd, const char *vmlinux);
> +char *addr2line_get_lines(uint64_t address);
> +int addr2line_cleanup(void);
> +const char *remove_subdir(const char *home, const char *f_path);
> +const char *get_addr2line(int mode);
> +char *get_vmlinux(char *input);
> +
> +#endif
> diff --git a/scripts/kas_alias/duplicates_list.c
> b/scripts/kas_alias/duplicates_list.c new file mode 100644
> index 000000000000..e7a3d2917937
> --- /dev/null
> +++ b/scripts/kas_alias/duplicates_list.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdlib.h>
> +#include <stdbool.h>
> +
> +#include "item_list.h"
> +#include "duplicates_list.h"
> +
> +struct duplicate_item *find_duplicates(struct item *list)
> +{
> + struct duplicate_item *current_duplicate = NULL;
> + struct duplicate_item *duplicates = NULL;
> + struct duplicate_item *new_duplicate;
> + struct item *current_item = list;
> + bool prev_was_duplicate = false;
> + struct item *prev_item = NULL;
> +
> + while (current_item) {
> + if ((prev_item && (strcmp(current_item->symb_name, prev_item-
>symb_name)
> == 0)) || + prev_was_duplicate) {
> + if (!duplicates) {
> + duplicates = malloc(sizeof(struct
duplicate_item));
> + if (!duplicates)
> + return NULL;
> +
> + duplicates->original_item = prev_item;
> + duplicates->next = NULL;
> + current_duplicate = duplicates;
> + } else {
> + new_duplicate = malloc(sizeof(struct
duplicate_item));
> + if (!new_duplicate) {
> + free_duplicates(&duplicates);
> + return NULL;
> + }
> +
> + new_duplicate->original_item = prev_item;
> + new_duplicate->next = NULL;
> + current_duplicate->next = new_duplicate;
> + current_duplicate = new_duplicate;
> +
> + if ((strcmp(current_item->symb_name, prev_item-
>symb_name) != 0) &&
> + (prev_was_duplicate))
> + prev_was_duplicate = false;
> + else
> + prev_was_duplicate = true;
You can remove the branch and set prev_was_duplicate to:
prev_was_duplicate = strcmp(current_item->symb_name, prev_item->symb_name) !=
0 && prev_was_duplicate;
> + }
> + }
> +
> + prev_item = current_item;
> + current_item = current_item->next;
> + }
> +
> + return duplicates;
> +}
> +
> +void free_duplicates(struct duplicate_item **duplicates)
> +{
> + struct duplicate_item *duplicates_iterator = *duplicates;
> + struct duplicate_item *app;
> +
> + while (duplicates_iterator) {
> + app = duplicates_iterator;
> + duplicates_iterator = duplicates_iterator->next;
> + free(app);
> + }
> +
> + *duplicates = NULL;
> +}
> diff --git a/scripts/kas_alias/duplicates_list.h
> b/scripts/kas_alias/duplicates_list.h new file mode 100644
> index 000000000000..76aa73e584bc
> --- /dev/null
> +++ b/scripts/kas_alias/duplicates_list.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef DUPLICATES_LIST_H
> +#define DUPLICATES_LIST_H
> +
> +#include "item_list.h"
> +
> +struct duplicate_item {
> + struct item *original_item;
> + struct duplicate_item *next;
> +};
> +
> +struct duplicate_item *find_duplicates(struct item *list);
> +void free_duplicates(struct duplicate_item **duplicates);
> +
> +#endif
> diff --git a/scripts/kas_alias/item_list.c b/scripts/kas_alias/item_list.c
> new file mode 100644
> index 000000000000..48f2e525592a
> --- /dev/null
> +++ b/scripts/kas_alias/item_list.c
> @@ -0,0 +1,230 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <assert.h>
> +#include "item_list.h"
> +
> +#define CHECK_ORDER_BY_ADDRESS(sort_by, current, temp, op) \
> + ((sort_by) == BY_ADDRESS && (current)->addr op (temp)->addr)
> +#define CHECK_ORDER_BY_NAME(sort_by, current, temp, op) \
> + ((sort_by) == BY_NAME && strcmp((current)->symb_name, (temp)-
>symb_name)
> op 0) +
> +struct item *list_index[96] = {0};
> +
> +void build_index(struct item *list)
> +{
> + char current_first_letter = ' ';
> + struct item *current = list;
> +
> + while (current) {
> + if (current->symb_name[0] != current_first_letter) {
> + current_first_letter = current->symb_name[0];
> + list_index[current_first_letter - 32] = current;
> + }
> + current = current->next;
> + }
> +}
> +
> +struct item *add_item(struct item **list, const char *name, char stype,
> uint64_t addr) +{
> + struct item *new_item;
> + struct item *current;
> +
> + new_item = malloc(sizeof(struct item));
> + if (!new_item)
> + return NULL;
> +
> + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> + new_item->addr = addr;
> + new_item->stype = stype;
> + new_item->next = NULL;
> +
> + if (!(*list)) {
> + *list = new_item;
> + } else {
> + current = *list;
> + while (current->next)
> + current = current->next;
> +
> + current->next = new_item;
> + }
> + return new_item;
> +}
> +
> +void sort_list(struct item **list, int sort_by)
> +{
> + struct item *current = *list;
> + struct item *sorted = NULL;
> + struct item *next_item;
> + struct item *temp;
> +
> + if (!(*list) || !((*list)->next))
> + return;
> +
> + while (current) {
> + next_item = current->next;
> + if (!sorted ||
> + (CHECK_ORDER_BY_ADDRESS(sort_by, current, sorted, <) ||
> + CHECK_ORDER_BY_NAME(sort_by, current, sorted, >=))) {
> + current->next = sorted;
> + sorted = current;
> + } else {
> + temp = sorted;
> + while (temp->next &&
> + (CHECK_ORDER_BY_ADDRESS(sort_by, current, temp-
>next, >=) ||
> + CHECK_ORDER_BY_NAME(sort_by, current, temp->next,
>=)))
> + temp = temp->next;
> +
> + current->next = temp->next;
> + temp->next = current;
> + }
> + current = next_item;
> + }
> +
> + *list = sorted;
> +}
> +
> +struct item *merge(struct item *left, struct item *right, int sort_by)
> +{
> + struct item *current = NULL;
> + struct item *result = NULL;
> +
> + if (!left)
> + return right;
> + if (!right)
> + return left;
> +
> + if (sort_by == BY_NAME) {
> + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> + result = left;
> + left = left->next;
> + } else {
> + result = right;
> + right = right->next;
> + }
> + } else {
> + if (sort_by == BY_ADDRESS) {
> + if (left->addr <= right->addr) {
> + result = left;
> + left = left->next;
> + } else {
> + result = right;
> + right = right->next;
> + }
> + }
> + }
> +
> + current = result;
> +
> + while (left && right) {
> + if (sort_by == BY_NAME) {
> + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> + current->next = left;
> + left = left->next;
> + } else {
> + current->next = right;
> + right = right->next;
> + }
> + } else {
> + if (sort_by == BY_ADDRESS) {
> + if (left->addr <= right->addr) {
> + current->next = left;
> + left = left->next;
> + } else {
> + current->next = right;
> + right = right->next;
> + }
> + }
> + }
> +
> + current = current->next;
> + }
> +
> + if (left) {
> + current->next = left;
> + } else {
> + if (right)
> + current->next = right;
> + }
> +
> + return result;
> +}
> +
> +struct item *merge_sort(struct item *head, int sort_by)
> +{
> + struct item *right;
> + struct item *slow;
> + struct item *fast;
> + struct item *left;
> +
> + if (!head || !head->next)
> + return head;
> +
> + slow = head;
> + fast = head->next;
> +
> + while (fast && fast->next) {
> + slow = slow->next;
> + fast = fast->next->next;
> + }
> +
> + left = head;
> + right = slow->next;
> + slow->next = NULL;
> +
> + left = merge_sort(left, sort_by);
> + right = merge_sort(right, sort_by);
> +
> + return merge(left, right, sort_by);
> +}
> +
> +void sort_list_m(struct item **head, int sort_by)
> +{
> + if (!(*head) || !((*head)->next))
> + return;
> +
> + *head = merge_sort(*head, sort_by);
> +}
> +
> +int insert_after(struct item *list, const uint64_t search_addr,
> + const char *name, uint64_t addr, char stype)
> +{
> + struct item *new_item;
> + struct item *current;
> + int ret = 0;
> +
> + current = (list_index[name[0] - 32]) ? list_index[name[0] - 32] :
list;
> + while (current) {
> + if (current->addr == search_addr) {
> + new_item = malloc(sizeof(struct item));
> + if (!new_item)
> + return ret;
> + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> + new_item->addr = addr;
> + new_item->stype = stype;
> + new_item->next = current->next;
> + current->next = new_item;
> + ret = 1;
> + break;
> + }
> + current = current->next;
> + }
> + return ret;
> +}
> +
> +void free_items(struct item **head)
> +{
> + struct item *app, *item_iterator = *head;
> +
> + while (item_iterator) {
> + app = item_iterator;
> + item_iterator = item_iterator->next;
> + free(app);
> + }
> + *head = NULL;
> +}
> diff --git a/scripts/kas_alias/item_list.h b/scripts/kas_alias/item_list.h
> new file mode 100644
> index 000000000000..b4891cb088ee
> --- /dev/null
> +++ b/scripts/kas_alias/item_list.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef ITEM_LIST_H
> +#define ITEM_LIST_H
> +#include <stdint.h>
> +
> +#define MAX_NAME_SIZE 256
> +#define BY_ADDRESS 1
> +#define BY_NAME 2
> +
> +struct item {
> + char symb_name[MAX_NAME_SIZE];
> + uint64_t addr;
> + char stype;
> + struct item *next;
> +};
> +
> +void build_index(struct item *list);
> +struct item *add_item(struct item **list, const char *name, char stype,
> uint64_t addr); +void sort_list(struct item **list, int sort_by);
> +struct item *merge(struct item *left, struct item *right, int sort_by);
> +struct item *merge_sort(struct item *head, int sort_by);
> +void sort_list_m(struct item **head, int sort_by);
> +int insert_after(struct item *list, const uint64_t search_addr,
> + const char *name, uint64_t addr, char stype);
> +void free_items(struct item **head);
> +#endif
> diff --git a/scripts/kas_alias/kas_alias.c b/scripts/kas_alias/kas_alias.c
> new file mode 100644
> index 000000000000..532aeb39f851
> --- /dev/null
> +++ b/scripts/kas_alias/kas_alias.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <stdarg.h>
> +#include <regex.h>
> +
> +#include "item_list.h"
> +#include "duplicates_list.h"
> +#include "a2l.h"
> +
> +#define SYMB_IS_TEXT(s) ((((s)->stype) == 't') || (((s)->stype) == 'T'))
> +#define SYMB_IS_DATA(s) ((((s)->stype) == 'b') || (((s)->stype) == 'B') ||
> \ + (((s)->stype) == 'd') || (((s)->stype) == 'D') || \
> + (((s)->stype) == 'r') || (((s)->stype) == 'R'))
> +#ifdef CONFIG_KALLSYMS_ALIAS_DATA
> +#define SYMB_NEEDS_ALIAS(s) (SYMB_IS_TEXT(s) || SYMB_IS_DATA(s))
> +#else
> +#define SYMB_NEEDS_ALIAS(s) SYMB_IS_TEXT(s)
> +#endif
> +#define FNOMATCH 0
> +#define FMATCH 1
> +#define EREGEX 2
> +
> +const char *ignore_regex[] = {
> + "^__cfi_.*$", // __cfi_ preamble
> +#ifndef CONFIG_KALLSYMS_ALIAS_DATA_ALL
> + "^_*TRACE_SYSTEM.*$",
> + "^__already_done\\.[0-9]+$", // Call a function once data
> + "^___tp_str\\.[0-9]+$",
> + "^___done\\.[0-9]+$",
> + "^__print_once\\.[0-9]+$",
> + "^_rs\\.[0-9]+$",
> + "^__compound_literal\\.[0-9]+$",
> + "^___once_key\\.[0-9]+$",
> + "^__func__\\.[0-9]+$",
> + "^__msg\\.[0-9]+$",
> + "^CSWTCH\\.[0-9]+$",
> + "^__flags\\.[0-9]+$",
> + "^__wkey.*$",
> + "^__mkey.*$",
> + "^__key.*$",
> +#endif
> + "^__pfx_.*$" // NOP-padding
> +};
> +
> +int suffix_serial;
> +
> +static inline void verbose_msg(bool verbose, const char *fmt, ...)
> +{
> + va_list args;
> +
> + va_start(args, fmt);
> + if (verbose)
> + printf(fmt, args);
> +
> + va_end(args);
> +}
> +
> +static void create_suffix(const char *name, char *output_suffix)
> +{
> + sprintf(output_suffix, "%s__alias__%d", name, suffix_serial++);
> +}
> +
> +static void create_file_suffix(const char *name, uint64_t address, char
> *output_suffix, char *cwd) +{
> + const char *f_path;
> + char *buf;
> + int i = 0;
> +
> + buf = addr2line_get_lines(address);
> + f_path = remove_subdir(cwd, buf);
> + if (f_path) {
> + sprintf(output_suffix, "%s@%s", name, f_path);
> + while (*(output_suffix + i) != '\0') {
> + switch (*(output_suffix + i)) {
> + case '/':
> + case ':':
> + case '.':
> + *(output_suffix + i) = '_';
> + break;
> + default:
> + }
> + i++;
> + }
> + } else {
> + create_suffix(name, output_suffix);
> + }
> +}
> +
> +static int filter_symbols(char *symbol, const char **ignore_list, int
> regex_no) +{
> + regex_t regex;
> + int res, i;
> +
> + for (i = 0; i < regex_no; i++) {
> + res = regcomp(®ex, ignore_list[i], REG_EXTENDED);
> + if (res)
> + return -EREGEX;
> +
> + res = regexec(®ex, symbol, 0, NULL, 0);
> + regfree(®ex);
> + switch (res) {
> + case 0:
> + return FMATCH;
> + case REG_NOMATCH:
> + break;
> + default:
> + return -EREGEX;
> + }
> + }
> +
> + return FNOMATCH;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + char t, sym_name[MAX_NAME_SIZE], new_name[MAX_NAME_SIZE + 15];
> + struct duplicate_item *duplicate_iterator;
> + struct duplicate_item *duplicate;
> + struct item *head = {NULL};
> + bool need_2_process = true;
> + struct item *last = {NULL};
> + struct item *current;
> + int verbose_mode = 0;
> + uint64_t address;
> + FILE *fp;
> + int res;
> +
> + if (argc < 2 || argc > 3) {
> + printf("Usage: %s <nmfile> [-verbose]\n", argv[0]);
> + return 1;
> + }
> +
> + if (argc == 3 && strcmp(argv[2], "-verbose") == 0)
> + verbose_mode = 1;
> +
> + verbose_msg(verbose_mode, "Scanning nm data(%s)\n", argv[1]);
> +
> + fp = fopen(argv[1], "r");
> + if (!fp) {
> + printf("Can't open input file.\n");
> + return 1;
> + }
> +
> + if (!addr2line_init(get_addr2line(A2L_DEFAULT), get_vmlinux(argv[1])))
> + return 1;
> +
> + while (fscanf(fp, "%lx %c %99s\n", &address, &t, sym_name) == 3) {
> + if (strstr(sym_name, "@_")) {
> + if (verbose_mode && need_2_process)
> + printf("Already processed\n");
> + need_2_process = false;
> + }
> + last = add_item(&last, sym_name, t, address);
> + if (!last) {
> + printf("Error in allocate memory\n");
> + free_items(&head);
> + return 1;
> + }
> +
> + if (!head)
> + head = last;
> + }
> +
> + fclose(fp);
> +
> + if (need_2_process) {
> + verbose_msg(verbose_mode, "Sorting nm data\n");
> + sort_list_m(&head, BY_NAME);
> + verbose_msg(verbose_mode, "Scanning nm data for duplicates\n");
> + duplicate = find_duplicates(head);
> + if (!duplicate) {
> + printf("Error in duplicates list\n");
> + return 1;
> + }
> +
> + verbose_msg(verbose_mode, "Applying suffixes\n");
> + build_index(head);
> + duplicate_iterator = duplicate;
> + while (duplicate_iterator) {
> + res = filter_symbols(duplicate_iterator->original_item-
>symb_name,
> + ignore_regex, sizeof(ignore_regex) /
> + sizeof(ignore_regex[0]));
> + if (res != FMATCH &&
> + SYMB_NEEDS_ALIAS(duplicate_iterator->original_item))
{
> + if (res < 0)
> + return 1;
> +
> + create_file_suffix(duplicate_iterator-
>original_item->symb_name,
> + duplicate_iterator-
>original_item->addr,
> + new_name, vmlinux_path);
> + if (!insert_after(head, duplicate_iterator-
>original_item->addr,
> + new_name, duplicate_iterator-
>original_item->addr,
> + duplicate_iterator-
>original_item->stype))
> + return 1;
> + }
> +
> + duplicate_iterator = duplicate_iterator->next;
> + }
> +
> + sort_list_m(&head, BY_ADDRESS);
> + }
> + current = head;
> + while (current) {
> + printf("%08lx %c %s\n", current->addr, current->stype,
> current->symb_name); + current = current->next;
> + }
> +
> + free_items(&head);
> + free_duplicates(&duplicate);
> + addr2line_cleanup();
> + return 0;
> +}
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index a432b171be82..cacf60b597ce 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -89,8 +89,9 @@ vmlinux_link()
>
> ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
>
> - # The kallsyms linking does not need debug symbols included.
> - if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> + # The kallsyms linking does not need debug symbols included, unless
the
> KALLSYMS_ALIAS. + if [ ! is_enabled CONFIG_KALLSYMS_ALIAS ] && \
> + [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> ldflags="${ldflags} ${wl}--strip-debug"
> fi
>
> @@ -161,7 +162,11 @@ kallsyms()
> fi
>
> info KSYMS ${2}
> - scripts/kallsyms ${kallsymopt} ${1} > ${2}
> + if is_enabled CONFIG_KALLSYMS_ALIAS; then
> + ALIAS=".alias"
> + scripts/kas_alias/kas_alias ${1} >${1}${ALIAS}
> + fi
> + scripts/kallsyms ${kallsymopt} ${1}${ALIAS} > ${2}
> }
>
> # Perform one step in kallsyms generation, including temporary linking of
Best regards.
Hi Alessandro,
Thanks for your update!
On Mon, 28 Aug 2023 08:04:23 +0000
"Alessandro Carminati (Red Hat)" <[email protected]> wrote:
> From: Alessandro Carminati <[email protected]>
>
> It is not uncommon for drivers or modules related to similar peripherals
> to have symbols with the exact same name.
> While this is not a problem for the kernel's binary itself, it becomes an
> issue when attempting to trace or probe specific functions using
> infrastructure like ftrace or kprobe.
>
> The tracing subsystem relies on the `nm -n vmlinux` output, which provides
> symbol information from the kernel's ELF binary. However, when multiple
> symbols share the same name, the standard nm output does not differentiate
> between them. This can lead to confusion and difficulty when trying to
> probe the intended symbol.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff8c4f76d0 t name_show
> ffffffff8c9cccb0 t name_show
> ffffffff8cb0ac20 t name_show
> ffffffff8cc728c0 t name_show
> ffffffff8ce0efd0 t name_show
> ffffffff8ce126c0 t name_show
> ffffffff8ce1dd20 t name_show
> ffffffff8ce24e70 t name_show
> ffffffff8d1104c0 t name_show
> ffffffff8d1fe480 t name_show
>
> **kas_alias** addresses this challenge by extending the symbol names with
> unique suffixes during the kernel build process.
> The newly created aliases for these duplicated symbols are unique names
> that can be fed to the ftracefs interface. By doing so, it enables
> previously unreachable symbols to be probed.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff974f76d0 t name_show
> ffffffff974f76d0 t name_show__alias__6340
> ffffffff979cccb0 t name_show
> ffffffff979cccb0 t name_show__alias__6341
> ffffffff97b0ac20 t name_show
> ffffffff97b0ac20 t name_show__alias__6342
> ffffffff97c728c0 t name_show
> ffffffff97c728c0 t name_show__alias__6343
> ffffffff97e0efd0 t name_show
> ffffffff97e0efd0 t name_show__alias__6344
> ffffffff97e126c0 t name_show
> ffffffff97e126c0 t name_show__alias__6345
> ffffffff97e1dd20 t name_show
> ffffffff97e1dd20 t name_show__alias__6346
> ffffffff97e24e70 t name_show
> ffffffff97e24e70 t name_show__alias__6347
> ffffffff981104c0 t name_show
> ffffffff981104c0 t name_show__alias__6348
> ffffffff981fe480 t name_show
> ffffffff981fe480 t name_show__alias__6349
> ~ # echo "p:kprobes/evnt1 name_show__alias__6349" \
> > >/sys/kernel/tracing/kprobe_events
> ~ # cat /sys/kernel/tracing/kprobe_events
> p:kprobes/evnt1 name_show__alias__6349
>
> Changes from v1:
> - Integrated changes requested by Masami to exclude symbols with prefixes
> "_cfi" and "_pfx".
> - Introduced a small framework to handle patterns that need to be excluded
> from the alias production.
> - Excluded other symbols using the framework.
> - Introduced the ability to discriminate between text and data symbols.
> - Added two new config symbols in this version: CONFIG_KALLSYMS_ALIAS_DATA,
> which allows data for data, and CONFIG_KALLSYMS_ALIAS_DATA_ALL, which
> excludes all filters and provides an alias for each duplicated symbol.
>
> https://lore.kernel.org/all/[email protected]/
>
> Changes from v2:
> - Alias tags are created by querying DWARF information from the vmlinux.
> - The filename + line number is normalized and appended to the original name.
> - The tag begins with '@' to indicate the symbol source.
> - Not a change, but worth mentioning, since the alias is added to the existing
> list, the old duplicated name is preserved, and the livepatch way of dealing
> with duplicates is maintained.
> - Acknowledging the existence of scenarios where inlined functions declared in
> header files may result in multiple copies due to compiler behavior, though
> it is not actionable as it does not pose an operational issue.
> - Highlighting a single exception where the same name refers to different
> functions: the case of "compat_binfmt_elf.c," which directly includes
> "binfmt_elf.c" producing identical function copies in two separate
> modules.
>
> sample from new v3
>
> ~ # cat /proc/kallsyms | grep gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> ffffd0b03c050960 t gic_mask_irq
> ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
Could you also update the sample output in the patch description?
And I can not see this line information but a serial number aliases,
is there any way to enable this file-name aliases? (LLVM is not supported?)
I think we'd better to have a new CONFIG_KALLSYMS_ALIAS_SRCLINE and
clarify what is required.
> ~ #
>
> https://lore.kernel.org/all/[email protected]/
>
> Signed-off-by: Alessandro Carminati (Red Hat) <[email protected]>
> ---
> init/Kconfig | 36 ++++
> scripts/Makefile | 4 +
> scripts/kas_alias/Makefile | 4 +
> scripts/kas_alias/a2l.c | 268 ++++++++++++++++++++++++++++
> scripts/kas_alias/a2l.h | 32 ++++
> scripts/kas_alias/duplicates_list.c | 70 ++++++++
> scripts/kas_alias/duplicates_list.h | 15 ++
> scripts/kas_alias/item_list.c | 230 ++++++++++++++++++++++++
> scripts/kas_alias/item_list.h | 26 +++
> scripts/kas_alias/kas_alias.c | 217 ++++++++++++++++++++++
> scripts/link-vmlinux.sh | 11 +-
> 11 files changed, 910 insertions(+), 3 deletions(-)
> create mode 100644 scripts/kas_alias/Makefile
> create mode 100644 scripts/kas_alias/a2l.c
> create mode 100644 scripts/kas_alias/a2l.h
> create mode 100644 scripts/kas_alias/duplicates_list.c
> create mode 100644 scripts/kas_alias/duplicates_list.h
> create mode 100644 scripts/kas_alias/item_list.c
> create mode 100644 scripts/kas_alias/item_list.h
> create mode 100644 scripts/kas_alias/kas_alias.c
>
> diff --git a/init/Kconfig b/init/Kconfig
> index f7f65af4ee12..bc69fcd9cbc8 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1737,6 +1737,42 @@ config KALLSYMS_BASE_RELATIVE
> time constants, and no relocation pass is required at runtime to fix
> up the entries based on the runtime load address of the kernel.
>
> +config KALLSYMS_ALIAS
> + bool "Produces alias for duplicated symbols" if EXPERT
> + depends on KALLSYMS && (DEBUG_INFO_DWARF4 || DEBUG_INFO_DWARF5)
> + help
> + It is not uncommon for drivers or modules related to similar
> + peripherals to have symbols with the exact same name.
> + While this is not a problem for the kernel's binary itself, it
> + becomes an issue when attempting to trace or probe specific
> + functions using infrastructure like ftrace or kprobe.
> +
> + This option addresses this challenge by extending the symbol names
> + with unique suffixes during the kernel build process.
> + The newly created aliases for these duplicated symbols are unique
> + names that can be fed to the ftrace sysfs interface. By doing so, it
> + enables previously unreachable symbols to be probed.
> +
> +config CONFIG_KALLSYMS_ALIAS_DATA
You don't need 'CONFIG_' prefix here.
> + bool "Produces alias also for data"
> + depends on KALLSYMS_ALIAS
> + help
> + Sometimes it can be useful to refer to data. In live patch scenarios,
> + you may find yourself needing to use symbols that are shared with
> + other functions. Since symbols face the same issue as functions, this
> + option allows you to create aliases for data as well.
> +
> +config CONFIG_KALLSYMS_ALIAS_DATA_ALL
> + bool "Removes all filter when producing data alias"
> + depends on CONFIG_KALLSYMS_ALIAS_DATA
> + help
> + When selecting data aliases, not all symbols are included in the set
> + This is because many symbols are unlikely to be used. If you choose
> + to have an alias for all data symbols, be aware that it will
> + significantly increase the size.
> +
> + If unsure, say N.
> +
> # end of the "standard kernel features (expert users)" menu
>
> # syscall, maps, verifier
> diff --git a/scripts/Makefile b/scripts/Makefile
> index 32b6ba722728..65fafe17cfe5 100644
> --- a/scripts/Makefile
> +++ b/scripts/Makefile
> @@ -49,3 +49,7 @@ subdir-$(CONFIG_SECURITY_SELINUX) += selinux
>
> # Let clean descend into subdirs
> subdir- += basic dtc gdb kconfig mod
> +
> +# KALLSyms alias
> +subdir-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
> +
> diff --git a/scripts/kas_alias/Makefile b/scripts/kas_alias/Makefile
> new file mode 100644
> index 000000000000..e1fde69232b4
> --- /dev/null
> +++ b/scripts/kas_alias/Makefile
> @@ -0,0 +1,4 @@
> +# SPDX-License-Identifier: GPL-2.0
> +hostprogs-always-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
> +
> +kas_alias-objs := duplicates_list.o item_list.o kas_alias.o a2l.o
> diff --git a/scripts/kas_alias/a2l.c b/scripts/kas_alias/a2l.c
> new file mode 100644
> index 000000000000..a9692ac30180
> --- /dev/null
> +++ b/scripts/kas_alias/a2l.c
> @@ -0,0 +1,268 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <string.h>
> +#include <stdint.h>
> +#include <stdbool.h>
> +
> +#include "a2l.h"
> +
> +int addr2line_pid = -1;
> +int a2l_in[2];
> +int a2l_out[2];
> +char line[MAX_BUF];
> +char vmlinux_path[MAX_BUF];
> +char addr2line_cmd[MAX_CMD_LEN];
> +FILE *a2l_stdin, *a2l_stdout;
> +
> +static char *normalize_path(const char *input_path, char *output_path)
> +{
> + char *prev_token = NULL;
> + char *delimiter = "/";
> + char inbuf[MAX_BUF];
> + char *token;
> + char *pos;
> +
> + memset(inbuf, 0, MAX_BUF);
> + *output_path = '\0';
> + strncpy(inbuf, input_path, MAX_BUF);
> + if (!input_path || !output_path || strlen(input_path) == 0)
> + return NULL;
> +
> + token = strtok(inbuf, delimiter);
> + while (token) {
> + if (strcmp(token, "..") == 0 && prev_token) {
> + pos = strrchr(output_path, '/');
> + if (pos)
> + *pos = '\0';
> +
> + } else if (strcmp(token, ".") != 0) {
> + strcat(output_path, "/");
> + strcat(output_path, token);
> + }
> +
> + prev_token = token;
> + token = strtok(NULL, delimiter);
> + }
> +
> + return output_path;
> +}
> +
> +static void path_of(const char *full_path, char *path)
> +{
> + const char *last_slash = strrchr(full_path, '/');
> + size_t path_length;
> + char cwd[MAX_BUF];
> +
> + if (!last_slash) {
> + if (getcwd(cwd, sizeof(cwd)))
> + strcpy(path, cwd);
> + else
> + strcpy(path, ".");
> + } else {
> + path_length = last_slash - full_path;
> + strncpy(path, full_path, path_length);
> + path[path_length] = '\0';
> + }
> +}
> +
> +static bool file_exists(const char *file_path)
> +{
> + FILE *file;
> +
> + file = fopen(file_path, "r");
> + if (file) {
> + fclose(file);
> + return true;
> + }
> + return false;
> +}
> +
> +int addr2line_init(const char *cmd, const char *vmlinux)
> +{
> + if ((!file_exists(cmd)) || (!file_exists(vmlinux))) {
> + printf("file not found\n");
> + return 0;
> + }
nit: mis-indentation?
> +
> + path_of(vmlinux, vmlinux_path);
> + if (pipe(a2l_in) == -1) {
> + printf("Failed to create pipe\n");
> + return 0;
> + }
> +
> + if (pipe(a2l_out) == -1) {
> + printf("Failed to create pipe\n");
> + return 0;
> + }
> +
> + addr2line_pid = fork();
> + if (addr2line_pid == -1) {
> + printf("Failed to fork process\n");
> + close(a2l_in[P_READ]);
> + close(a2l_in[P_WRITE]);
> + close(a2l_out[P_READ]);
> + close(a2l_out[P_WRITE]);
> + return 0;
> + }
> +
> + if (addr2line_pid == 0) {
> + dup2(a2l_in[P_READ], 0);
> + dup2(a2l_out[P_WRITE], 1);
> + close(a2l_in[P_WRITE]);
> + close(a2l_out[P_READ]);
> +
> + execlp(cmd, cmd, ADDR2LINE_ARGS, vmlinux, NULL);
> +
> + printf("Failed to execute addr2line command\n");
> + exit(1);
> + } else {
> + close(a2l_in[P_READ]);
> + close(a2l_out[P_WRITE]);
> + }
> +
> + a2l_stdin = fdopen(a2l_in[P_WRITE], "w");
> + if (!a2l_stdin) {
> + printf("Failed to open pipe a2l_in\n");
> + return 0;
> + }
> +
> + a2l_stdout = fdopen(a2l_out[P_READ], "r");
> + if (!a2l_stdout) {
> + printf("Failed to open pipe a2l_out\n");
> + fclose(a2l_stdin);
> + return 0;
> + }
> +
> + return 1;
> +}
> +
> +const char *remove_subdir(const char *home, const char *f_path)
> +{
> + int i = 0;
> +
> + while (*(home + i) == *(f_path + i))
> + i++;
> +
> + return (strlen(home) != i) ? NULL : f_path + i;
> +}
> +
> +char *addr2line_get_lines(uint64_t address)
> +{
> + char buf[MAX_BUF];
> +
> + fprintf(a2l_stdin, "%08lx\n", address);
> + fflush(a2l_stdin);
> +
> + if (!fgets(line, sizeof(line), a2l_stdout)) {
> + printf("Failed to read lines from addr2line\n");
> + return NULL;
> + }
> +
> + if (!fgets(line, sizeof(line), a2l_stdout)) {
> + printf("Failed to read lines from addr2line\n");
> + return NULL;
> + }
> +
> + line[strcspn(line, "\n")] = '\0';
> + strncpy(buf, line, MAX_BUF);
> + return normalize_path(buf, line);
> +}
> +
> +int addr2line_cleanup(void)
> +{
> + int status;
> +
> + if (addr2line_pid != -1) {
> + kill(addr2line_pid, SIGKILL);
> + waitpid(addr2line_pid, &status, 0);
> + fclose(a2l_stdin);
> + fclose(a2l_stdout);
> + addr2line_pid = -1;
> + }
> +
> + return 1;
> +}
> +
> +static char *find_executable(const char *command)
> +{
> + char *path_env = getenv("PATH");
> + char *executable_path;
> + char *path_copy;
> + char *path;
> + int n;
> +
> + if (!path_env)
> + return NULL;
> +
> + path_copy = strdup(path_env);
> + if (!path_copy)
> + return NULL;
> +
> + path = strtok(path_copy, ":");
> + while (path) {
> + n = snprintf(0, 0, "%s/%s", path, command);
> + executable_path = (char *)malloc(n + 1);
> + snprintf(executable_path, n + 1, "%s/%s", path, command);
> + if (access(executable_path, X_OK) == 0) {
> + free(path_copy);
> + return executable_path;
> + }
> +
> + path = strtok(NULL, ":");
> + free(executable_path);
> + executable_path = NULL;
nit: mis-indentation?
> + }
> +
> + free(path_copy);
> + if (executable_path)
> + free(executable_path);
> + return NULL;
> +}
> +
> +const char *get_addr2line(int mode)
> +{
> + char *buf = "";
> +
> + switch (mode) {
> + case A2L_CROSS:
> + buf = getenv("CROSS_COMPILE");
> + memcpy(addr2line_cmd, buf, strlen(buf));
> + case A2L_DEFAULT:
> + memcpy(addr2line_cmd + strlen(buf), ADDR2LINE, strlen(ADDR2LINE));
> + buf = find_executable(addr2line_cmd);
> + if (buf) {
> + memcpy(addr2line_cmd, buf, strlen(buf));
> + free(buf);
> + }
> + return addr2line_cmd;
> + case A2L_LLVM:
> + default:
> + return NULL;
> + }
> +}
> +
> +char *get_vmlinux(char *input)
> +{
> + const char *match_string1 = ".syms";
> + const char *match_string2 = ".tmp_vmlinux.kallsyms";
> + char *result = NULL;
> + char *match_pos;
> +
> + match_pos = strstr(input, match_string1);
> + if (!match_pos)
> + return NULL;
> +
> + match_pos = strstr(input, match_string2);
> + if (!match_pos)
> + return NULL;
> +
> + result = strdup(input);
> + match_pos = strstr(result, match_string1);
> + *match_pos = '\0';
> + return result;
> +}
> diff --git a/scripts/kas_alias/a2l.h b/scripts/kas_alias/a2l.h
> new file mode 100644
> index 000000000000..ca6419229dde
> --- /dev/null
> +++ b/scripts/kas_alias/a2l.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef A2L_H
> +#define A2L_H
> +#include <stdint.h>
> +
> +#define ADDR2LINE "addr2line"
> +#define ADDR2LINE_ARGS "-fe"
> +//#define VMLINUX "vmlinux"
Nit: this should be removed if it is not used.
> +#define MAX_BUF 4096
> +#define MAX_CMD_LEN 256
> +#define P_READ 0
> +#define P_WRITE 1
> +#define A2L_DEFAULT 1
> +#define A2L_CROSS 2
> +#define A2L_LLVM 3
> +#define A2L_MAKE_VALUE 2
> +
> +extern int addr2line_pid;
> +extern int a2l_in[2];
> +extern int a2l_out[2];
> +extern char line[MAX_BUF];
> +extern char vmlinux_path[MAX_BUF];
> +extern char addr2line_cmd[MAX_CMD_LEN];
> +
> +int addr2line_init(const char *cmd, const char *vmlinux);
> +char *addr2line_get_lines(uint64_t address);
> +int addr2line_cleanup(void);
> +const char *remove_subdir(const char *home, const char *f_path);
> +const char *get_addr2line(int mode);
> +char *get_vmlinux(char *input);
> +
> +#endif
> diff --git a/scripts/kas_alias/duplicates_list.c b/scripts/kas_alias/duplicates_list.c
> new file mode 100644
> index 000000000000..e7a3d2917937
> --- /dev/null
> +++ b/scripts/kas_alias/duplicates_list.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdlib.h>
> +#include <stdbool.h>
> +
> +#include "item_list.h"
> +#include "duplicates_list.h"
> +
/* The item list must be sorted. */
I think we can find the duplicated symbol without sorting the list,
but such implementation level optimization will be done later.
> +struct duplicate_item *find_duplicates(struct item *list)
> +{
> + struct duplicate_item *current_duplicate = NULL;
> + struct duplicate_item *duplicates = NULL;
> + struct duplicate_item *new_duplicate;
> + struct item *current_item = list;
> + bool prev_was_duplicate = false;
> + struct item *prev_item = NULL;
> +
> + while (current_item) {
> + if ((prev_item && (strcmp(current_item->symb_name, prev_item->symb_name) == 0)) ||
> + prev_was_duplicate) {
> + if (!duplicates) {
> + duplicates = malloc(sizeof(struct duplicate_item));
> + if (!duplicates)
> + return NULL;
> +
> + duplicates->original_item = prev_item;
> + duplicates->next = NULL;
> + current_duplicate = duplicates;
> + } else {
> + new_duplicate = malloc(sizeof(struct duplicate_item));
> + if (!new_duplicate) {
> + free_duplicates(&duplicates);
> + return NULL;
> + }
> +
> + new_duplicate->original_item = prev_item;
> + new_duplicate->next = NULL;
> + current_duplicate->next = new_duplicate;
> + current_duplicate = new_duplicate;
> +
> + if ((strcmp(current_item->symb_name, prev_item->symb_name) != 0) &&
> + (prev_was_duplicate))
> + prev_was_duplicate = false;
> + else
> + prev_was_duplicate = true;
> + }
> + }
> +
> + prev_item = current_item;
> + current_item = current_item->next;
> + }
> +
> + return duplicates;
> +}
> +
> +void free_duplicates(struct duplicate_item **duplicates)
> +{
> + struct duplicate_item *duplicates_iterator = *duplicates;
> + struct duplicate_item *app;
> +
> + while (duplicates_iterator) {
> + app = duplicates_iterator;
> + duplicates_iterator = duplicates_iterator->next;
> + free(app);
> + }
> +
> + *duplicates = NULL;
> +}
> diff --git a/scripts/kas_alias/duplicates_list.h b/scripts/kas_alias/duplicates_list.h
> new file mode 100644
> index 000000000000..76aa73e584bc
> --- /dev/null
> +++ b/scripts/kas_alias/duplicates_list.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef DUPLICATES_LIST_H
> +#define DUPLICATES_LIST_H
> +
> +#include "item_list.h"
> +
> +struct duplicate_item {
> + struct item *original_item;
> + struct duplicate_item *next;
> +};
> +
> +struct duplicate_item *find_duplicates(struct item *list);
> +void free_duplicates(struct duplicate_item **duplicates);
> +
> +#endif
> diff --git a/scripts/kas_alias/item_list.c b/scripts/kas_alias/item_list.c
> new file mode 100644
> index 000000000000..48f2e525592a
> --- /dev/null
> +++ b/scripts/kas_alias/item_list.c
> @@ -0,0 +1,230 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <assert.h>
> +#include "item_list.h"
> +
> +#define CHECK_ORDER_BY_ADDRESS(sort_by, current, temp, op) \
> + ((sort_by) == BY_ADDRESS && (current)->addr op (temp)->addr)
> +#define CHECK_ORDER_BY_NAME(sort_by, current, temp, op) \
> + ((sort_by) == BY_NAME && strcmp((current)->symb_name, (temp)->symb_name) op 0)
> +
> +struct item *list_index[96] = {0};
> +
> +void build_index(struct item *list)
> +{
> + char current_first_letter = ' ';
> + struct item *current = list;
> +
> + while (current) {
> + if (current->symb_name[0] != current_first_letter) {
> + current_first_letter = current->symb_name[0];
> + list_index[current_first_letter - 32] = current;
> + }
> + current = current->next;
> + }
> +}
> +
> +struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr)
> +{
> + struct item *new_item;
> + struct item *current;
> +
> + new_item = malloc(sizeof(struct item));
> + if (!new_item)
> + return NULL;
> +
> + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> + new_item->addr = addr;
> + new_item->stype = stype;
> + new_item->next = NULL;
> +
> + if (!(*list)) {
> + *list = new_item;
> + } else {
> + current = *list;
> + while (current->next)
> + current = current->next;
> +
> + current->next = new_item;
> + }
> + return new_item;
> +}
> +
> +void sort_list(struct item **list, int sort_by)
> +{
> + struct item *current = *list;
> + struct item *sorted = NULL;
> + struct item *next_item;
> + struct item *temp;
> +
> + if (!(*list) || !((*list)->next))
> + return;
> +
> + while (current) {
> + next_item = current->next;
> + if (!sorted ||
> + (CHECK_ORDER_BY_ADDRESS(sort_by, current, sorted, <) ||
> + CHECK_ORDER_BY_NAME(sort_by, current, sorted, >=))) {
> + current->next = sorted;
> + sorted = current;
> + } else {
> + temp = sorted;
> + while (temp->next &&
> + (CHECK_ORDER_BY_ADDRESS(sort_by, current, temp->next, >=) ||
> + CHECK_ORDER_BY_NAME(sort_by, current, temp->next, >=)))
> + temp = temp->next;
> +
> + current->next = temp->next;
> + temp->next = current;
> + }
> + current = next_item;
> + }
> +
> + *list = sorted;
> +}
> +
> +struct item *merge(struct item *left, struct item *right, int sort_by)
> +{
> + struct item *current = NULL;
> + struct item *result = NULL;
> +
> + if (!left)
> + return right;
> + if (!right)
> + return left;
> +
> + if (sort_by == BY_NAME) {
> + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> + result = left;
> + left = left->next;
> + } else {
> + result = right;
> + right = right->next;
> + }
> + } else {
> + if (sort_by == BY_ADDRESS) {
> + if (left->addr <= right->addr) {
> + result = left;
> + left = left->next;
> + } else {
> + result = right;
> + right = right->next;
> + }
> + }
> + }
> +
> + current = result;
> +
> + while (left && right) {
> + if (sort_by == BY_NAME) {
> + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> + current->next = left;
> + left = left->next;
> + } else {
> + current->next = right;
> + right = right->next;
> + }
> + } else {
> + if (sort_by == BY_ADDRESS) {
> + if (left->addr <= right->addr) {
> + current->next = left;
> + left = left->next;
> + } else {
> + current->next = right;
> + right = right->next;
> + }
> + }
> + }
> +
> + current = current->next;
> + }
> +
> + if (left) {
> + current->next = left;
> + } else {
> + if (right)
> + current->next = right;
> + }
> +
> + return result;
> +}
> +
> +struct item *merge_sort(struct item *head, int sort_by)
> +{
> + struct item *right;
> + struct item *slow;
> + struct item *fast;
> + struct item *left;
> +
> + if (!head || !head->next)
> + return head;
> +
> + slow = head;
> + fast = head->next;
> +
> + while (fast && fast->next) {
> + slow = slow->next;
> + fast = fast->next->next;
> + }
> +
> + left = head;
> + right = slow->next;
> + slow->next = NULL;
> +
> + left = merge_sort(left, sort_by);
> + right = merge_sort(right, sort_by);
> +
> + return merge(left, right, sort_by);
> +}
> +
> +void sort_list_m(struct item **head, int sort_by)
> +{
> + if (!(*head) || !((*head)->next))
> + return;
> +
> + *head = merge_sort(*head, sort_by);
> +}
> +
> +int insert_after(struct item *list, const uint64_t search_addr,
> + const char *name, uint64_t addr, char stype)
> +{
> + struct item *new_item;
> + struct item *current;
> + int ret = 0;
> +
> + current = (list_index[name[0] - 32]) ? list_index[name[0] - 32] : list;
> + while (current) {
> + if (current->addr == search_addr) {
> + new_item = malloc(sizeof(struct item));
> + if (!new_item)
> + return ret;
> + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> + new_item->addr = addr;
> + new_item->stype = stype;
> + new_item->next = current->next;
> + current->next = new_item;
> + ret = 1;
> + break;
> + }
> + current = current->next;
> + }
> + return ret;
> +}
> +
> +void free_items(struct item **head)
> +{
> + struct item *app, *item_iterator = *head;
> +
> + while (item_iterator) {
> + app = item_iterator;
> + item_iterator = item_iterator->next;
> + free(app);
> + }
> + *head = NULL;
> +}
> diff --git a/scripts/kas_alias/item_list.h b/scripts/kas_alias/item_list.h
> new file mode 100644
> index 000000000000..b4891cb088ee
> --- /dev/null
> +++ b/scripts/kas_alias/item_list.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef ITEM_LIST_H
> +#define ITEM_LIST_H
> +#include <stdint.h>
> +
> +#define MAX_NAME_SIZE 256
> +#define BY_ADDRESS 1
> +#define BY_NAME 2
> +
> +struct item {
> + char symb_name[MAX_NAME_SIZE];
> + uint64_t addr;
> + char stype;
> + struct item *next;
> +};
> +
> +void build_index(struct item *list);
> +struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr);
> +void sort_list(struct item **list, int sort_by);
> +struct item *merge(struct item *left, struct item *right, int sort_by);
> +struct item *merge_sort(struct item *head, int sort_by);
> +void sort_list_m(struct item **head, int sort_by);
> +int insert_after(struct item *list, const uint64_t search_addr,
> + const char *name, uint64_t addr, char stype);
> +void free_items(struct item **head);
> +#endif
> diff --git a/scripts/kas_alias/kas_alias.c b/scripts/kas_alias/kas_alias.c
> new file mode 100644
> index 000000000000..532aeb39f851
> --- /dev/null
> +++ b/scripts/kas_alias/kas_alias.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <stdarg.h>
> +#include <regex.h>
> +
> +#include "item_list.h"
> +#include "duplicates_list.h"
> +#include "a2l.h"
> +
> +#define SYMB_IS_TEXT(s) ((((s)->stype) == 't') || (((s)->stype) == 'T'))
> +#define SYMB_IS_DATA(s) ((((s)->stype) == 'b') || (((s)->stype) == 'B') || \
> + (((s)->stype) == 'd') || (((s)->stype) == 'D') || \
> + (((s)->stype) == 'r') || (((s)->stype) == 'R'))
> +#ifdef CONFIG_KALLSYMS_ALIAS_DATA
> +#define SYMB_NEEDS_ALIAS(s) (SYMB_IS_TEXT(s) || SYMB_IS_DATA(s))
> +#else
> +#define SYMB_NEEDS_ALIAS(s) SYMB_IS_TEXT(s)
> +#endif
> +#define FNOMATCH 0
> +#define FMATCH 1
> +#define EREGEX 2
> +
> +const char *ignore_regex[] = {
> + "^__cfi_.*$", // __cfi_ preamble
> +#ifndef CONFIG_KALLSYMS_ALIAS_DATA_ALL
> + "^_*TRACE_SYSTEM.*$",
> + "^__already_done\\.[0-9]+$", // Call a function once data
> + "^___tp_str\\.[0-9]+$",
> + "^___done\\.[0-9]+$",
> + "^__print_once\\.[0-9]+$",
> + "^_rs\\.[0-9]+$",
> + "^__compound_literal\\.[0-9]+$",
> + "^___once_key\\.[0-9]+$",
> + "^__func__\\.[0-9]+$",
> + "^__msg\\.[0-9]+$",
> + "^CSWTCH\\.[0-9]+$",
> + "^__flags\\.[0-9]+$",
> + "^__wkey.*$",
> + "^__mkey.*$",
> + "^__key.*$",
> +#endif
> + "^__pfx_.*$" // NOP-padding
> +};
> +
> +int suffix_serial;
> +
> +static inline void verbose_msg(bool verbose, const char *fmt, ...)
> +{
> + va_list args;
> +
> + va_start(args, fmt);
> + if (verbose)
> + printf(fmt, args);
> +
> + va_end(args);
> +}
> +
> +static void create_suffix(const char *name, char *output_suffix)
> +{
> + sprintf(output_suffix, "%s__alias__%d", name, suffix_serial++);
> +}
> +
> +static void create_file_suffix(const char *name, uint64_t address, char *output_suffix, char *cwd)
> +{
> + const char *f_path;
> + char *buf;
> + int i = 0;
> +
> + buf = addr2line_get_lines(address);
> + f_path = remove_subdir(cwd, buf);
> + if (f_path) {
> + sprintf(output_suffix, "%s@%s", name, f_path);
> + while (*(output_suffix + i) != '\0') {
> + switch (*(output_suffix + i)) {
> + case '/':
> + case ':':
> + case '.':
This is not enough because file path will accept more than that.
E.g. '+', '&', '-'.
So I think we should check it by '!isalnum()'. (allow-list method)
> + *(output_suffix + i) = '_';
> + break;
> + default:
> + }
> + i++;
> + }
> + } else {
> + create_suffix(name, output_suffix);
> + }
> +}
> +
> +static int filter_symbols(char *symbol, const char **ignore_list, int regex_no)
> +{
> + regex_t regex;
> + int res, i;
> +
> + for (i = 0; i < regex_no; i++) {
> + res = regcomp(®ex, ignore_list[i], REG_EXTENDED);
> + if (res)
> + return -EREGEX;
> +
> + res = regexec(®ex, symbol, 0, NULL, 0);
> + regfree(®ex);
> + switch (res) {
> + case 0:
> + return FMATCH;
> + case REG_NOMATCH:
> + break;
> + default:
> + return -EREGEX;
> + }
> + }
> +
> + return FNOMATCH;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + char t, sym_name[MAX_NAME_SIZE], new_name[MAX_NAME_SIZE + 15];
> + struct duplicate_item *duplicate_iterator;
> + struct duplicate_item *duplicate;
> + struct item *head = {NULL};
> + bool need_2_process = true;
> + struct item *last = {NULL};
> + struct item *current;
> + int verbose_mode = 0;
> + uint64_t address;
> + FILE *fp;
> + int res;
> +
> + if (argc < 2 || argc > 3) {
> + printf("Usage: %s <nmfile> [-verbose]\n", argv[0]);
> + return 1;
> + }
> +
> + if (argc == 3 && strcmp(argv[2], "-verbose") == 0)
> + verbose_mode = 1;
> +
> + verbose_msg(verbose_mode, "Scanning nm data(%s)\n", argv[1]);
> +
> + fp = fopen(argv[1], "r");
> + if (!fp) {
> + printf("Can't open input file.\n");
> + return 1;
> + }
> +
> + if (!addr2line_init(get_addr2line(A2L_DEFAULT), get_vmlinux(argv[1])))
> + return 1;
> +
> + while (fscanf(fp, "%lx %c %99s\n", &address, &t, sym_name) == 3) {
> + if (strstr(sym_name, "@_")) {
> + if (verbose_mode && need_2_process)
> + printf("Already processed\n");
> + need_2_process = false;
> + }
> + last = add_item(&last, sym_name, t, address);
> + if (!last) {
> + printf("Error in allocate memory\n");
> + free_items(&head);
> + return 1;
> + }
> +
> + if (!head)
> + head = last;
> + }
> +
> + fclose(fp);
> +
> + if (need_2_process) {
> + verbose_msg(verbose_mode, "Sorting nm data\n");
> + sort_list_m(&head, BY_NAME);
> + verbose_msg(verbose_mode, "Scanning nm data for duplicates\n");
> + duplicate = find_duplicates(head);
> + if (!duplicate) {
> + printf("Error in duplicates list\n");
> + return 1;
> + }
> +
> + verbose_msg(verbose_mode, "Applying suffixes\n");
> + build_index(head);
> + duplicate_iterator = duplicate;
> + while (duplicate_iterator) {
> + res = filter_symbols(duplicate_iterator->original_item->symb_name,
> + ignore_regex, sizeof(ignore_regex) /
> + sizeof(ignore_regex[0]));
> + if (res != FMATCH &&
> + SYMB_NEEDS_ALIAS(duplicate_iterator->original_item)) {
> + if (res < 0)
> + return 1;
> +
> + create_file_suffix(duplicate_iterator->original_item->symb_name,
> + duplicate_iterator->original_item->addr,
> + new_name, vmlinux_path);
> + if (!insert_after(head, duplicate_iterator->original_item->addr,
> + new_name, duplicate_iterator->original_item->addr,
> + duplicate_iterator->original_item->stype))
> + return 1;
> + }
> +
> + duplicate_iterator = duplicate_iterator->next;
> + }
> +
> + sort_list_m(&head, BY_ADDRESS);
> + }
> + current = head;
> + while (current) {
> + printf("%08lx %c %s\n", current->addr, current->stype, current->symb_name);
> + current = current->next;
> + }
> +
> + free_items(&head);
> + free_duplicates(&duplicate);
> + addr2line_cleanup();
> + return 0;
> +}
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index a432b171be82..cacf60b597ce 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -89,8 +89,9 @@ vmlinux_link()
>
> ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
>
> - # The kallsyms linking does not need debug symbols included.
> - if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> + # The kallsyms linking does not need debug symbols included, unless the KALLSYMS_ALIAS.
> + if [ ! is_enabled CONFIG_KALLSYMS_ALIAS ] && \
> + [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> ldflags="${ldflags} ${wl}--strip-debug"
> fi
>
> @@ -161,7 +162,11 @@ kallsyms()
> fi
>
> info KSYMS ${2}
> - scripts/kallsyms ${kallsymopt} ${1} > ${2}
> + if is_enabled CONFIG_KALLSYMS_ALIAS; then
> + ALIAS=".alias"
> + scripts/kas_alias/kas_alias ${1} >${1}${ALIAS}
> + fi
Nit: wrong indentation.
And ALIAS is not defined if CONFIG_KALLSYMS_ALIAS=n.
> + scripts/kallsyms ${kallsymopt} ${1}${ALIAS} > ${2}
> }
>
> # Perform one step in kallsyms generation, including temporary linking of
> --
> 2.34.1
>
Thank you,
--
Masami Hiramatsu (Google) <[email protected]>
On Mon, Aug 28, 2023 at 8:45 PM Alessandro Carminati (Red Hat)
<[email protected]> wrote:
>
> From: Alessandro Carminati <[email protected]>
>
> It is not uncommon for drivers or modules related to similar peripherals
> to have symbols with the exact same name.
> While this is not a problem for the kernel's binary itself, it becomes an
> issue when attempting to trace or probe specific functions using
> infrastructure like ftrace or kprobe.
>
> The tracing subsystem relies on the `nm -n vmlinux` output, which provides
> symbol information from the kernel's ELF binary. However, when multiple
> symbols share the same name, the standard nm output does not differentiate
> between them. This can lead to confusion and difficulty when trying to
> probe the intended symbol.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff8c4f76d0 t name_show
> ffffffff8c9cccb0 t name_show
> ffffffff8cb0ac20 t name_show
> ffffffff8cc728c0 t name_show
> ffffffff8ce0efd0 t name_show
> ffffffff8ce126c0 t name_show
> ffffffff8ce1dd20 t name_show
> ffffffff8ce24e70 t name_show
> ffffffff8d1104c0 t name_show
> ffffffff8d1fe480 t name_show
>
> **kas_alias** addresses this challenge by extending the symbol names with
> unique suffixes during the kernel build process.
> The newly created aliases for these duplicated symbols are unique names
> that can be fed to the ftracefs interface. By doing so, it enables
> previously unreachable symbols to be probed.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff974f76d0 t name_show
> ffffffff974f76d0 t name_show__alias__6340
> ffffffff979cccb0 t name_show
> ffffffff979cccb0 t name_show__alias__6341
> ffffffff97b0ac20 t name_show
> ffffffff97b0ac20 t name_show__alias__6342
> ffffffff97c728c0 t name_show
> ffffffff97c728c0 t name_show__alias__6343
> ffffffff97e0efd0 t name_show
> ffffffff97e0efd0 t name_show__alias__6344
> ffffffff97e126c0 t name_show
> ffffffff97e126c0 t name_show__alias__6345
> ffffffff97e1dd20 t name_show
> ffffffff97e1dd20 t name_show__alias__6346
> ffffffff97e24e70 t name_show
> ffffffff97e24e70 t name_show__alias__6347
> ffffffff981104c0 t name_show
> ffffffff981104c0 t name_show__alias__6348
> ffffffff981fe480 t name_show
> ffffffff981fe480 t name_show__alias__6349
>
> ~ # echo "p:kprobes/evnt1 name_show__alias__6349" \
> > >/sys/kernel/tracing/kprobe_events
> ~ # cat /sys/kernel/tracing/kprobe_events
> p:kprobes/evnt1 name_show__alias__6349
>
> Changes from v1:
> - Integrated changes requested by Masami to exclude symbols with prefixes
> "_cfi" and "_pfx".
> - Introduced a small framework to handle patterns that need to be excluded
> from the alias production.
> - Excluded other symbols using the framework.
> - Introduced the ability to discriminate between text and data symbols.
> - Added two new config symbols in this version: CONFIG_KALLSYMS_ALIAS_DATA,
> which allows data for data, and CONFIG_KALLSYMS_ALIAS_DATA_ALL, which
> excludes all filters and provides an alias for each duplicated symbol.
>
> https://lore.kernel.org/all/[email protected]/
>
> Changes from v2:
> - Alias tags are created by querying DWARF information from the vmlinux.
> - The filename + line number is normalized and appended to the original name.
> - The tag begins with '@' to indicate the symbol source.
> - Not a change, but worth mentioning, since the alias is added to the existing
> list, the old duplicated name is preserved, and the livepatch way of dealing
> with duplicates is maintained.
> - Acknowledging the existence of scenarios where inlined functions declared in
> header files may result in multiple copies due to compiler behavior, though
> it is not actionable as it does not pose an operational issue.
> - Highlighting a single exception where the same name refers to different
> functions: the case of "compat_binfmt_elf.c," which directly includes
> "binfmt_elf.c" producing identical function copies in two separate
> modules.
>
> sample from new v3
>
> ~ # cat /proc/kallsyms | grep gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> ffffd0b03c050960 t gic_mask_irq
> ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
> ~ #
>
> https://lore.kernel.org/all/[email protected]/
>
> Signed-off-by: Alessandro Carminati (Red Hat) <[email protected]>
> ---
> init/Kconfig | 36 ++++
> scripts/Makefile | 4 +
> scripts/kas_alias/Makefile | 4 +
> scripts/kas_alias/a2l.c | 268 ++++++++++++++++++++++++++++
> scripts/kas_alias/a2l.h | 32 ++++
> scripts/kas_alias/duplicates_list.c | 70 ++++++++
> scripts/kas_alias/duplicates_list.h | 15 ++
> scripts/kas_alias/item_list.c | 230 ++++++++++++++++++++++++
> scripts/kas_alias/item_list.h | 26 +++
> scripts/kas_alias/kas_alias.c | 217 ++++++++++++++++++++++
> scripts/link-vmlinux.sh | 11 +-
> 11 files changed, 910 insertions(+), 3 deletions(-)
> create mode 100644 scripts/kas_alias/Makefile
> create mode 100644 scripts/kas_alias/a2l.c
> create mode 100644 scripts/kas_alias/a2l.h
> create mode 100644 scripts/kas_alias/duplicates_list.c
> create mode 100644 scripts/kas_alias/duplicates_list.h
> create mode 100644 scripts/kas_alias/item_list.c
> create mode 100644 scripts/kas_alias/item_list.h
> create mode 100644 scripts/kas_alias/kas_alias.c
>
> diff --git a/init/Kconfig b/init/Kconfig
> index f7f65af4ee12..bc69fcd9cbc8 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1737,6 +1737,42 @@ config KALLSYMS_BASE_RELATIVE
> time constants, and no relocation pass is required at runtime to fix
> up the entries based on the runtime load address of the kernel.
>
> +config KALLSYMS_ALIAS
> + bool "Produces alias for duplicated symbols" if EXPERT
> + depends on KALLSYMS && (DEBUG_INFO_DWARF4 || DEBUG_INFO_DWARF5)
You can simplify this to
depends on KALLSYMS && DEBUG_INFO
I re-checked the commit log of
a66049e2cf0ef166dba5bafdbb3062287fc965ad
It says "GCC since ~4.8 has defaulted to DWARF v4
implicitly, and GCC 11 has bumped this to v5"
When DEBUG_INFO is enabled, the dwarf version is 4 or 5.
Presumably, your code does not work with DEBUG_INFO_SPLIT
depends on KALLSYMS && DEBUG_INFO && !DEBUG_INFO_SPLIT
> diff --git a/scripts/kas_alias/a2l.c b/scripts/kas_alias/a2l.c
> new file mode 100644
> index 000000000000..a9692ac30180
> --- /dev/null
> +++ b/scripts/kas_alias/a2l.c
> @@ -0,0 +1,268 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <string.h>
<string.h> is included twice.
I always sort include directives alphabetically
to avoid such a mistake.
> +#include <stdint.h>
> +#include <stdbool.h>
> +
> +#include "a2l.h"
> +
> +int addr2line_pid = -1;
> +int a2l_in[2];
> +int a2l_out[2];
> +char line[MAX_BUF];
> +char vmlinux_path[MAX_BUF];
> +char addr2line_cmd[MAX_CMD_LEN];
> +FILE *a2l_stdin, *a2l_stdout;
> +
> +static char *normalize_path(const char *input_path, char *output_path)
> +{
> + char *prev_token = NULL;
> + char *delimiter = "/";
> + char inbuf[MAX_BUF];
> + char *token;
> + char *pos;
> +
> + memset(inbuf, 0, MAX_BUF);
> + *output_path = '\0';
> + strncpy(inbuf, input_path, MAX_BUF);
> + if (!input_path || !output_path || strlen(input_path) == 0)
> + return NULL;
> +
> + token = strtok(inbuf, delimiter);
> + while (token) {
> + if (strcmp(token, "..") == 0 && prev_token) {
> + pos = strrchr(output_path, '/');
> + if (pos)
> + *pos = '\0';
> +
> + } else if (strcmp(token, ".") != 0) {
> + strcat(output_path, "/");
> + strcat(output_path, token);
> + }
> +
> + prev_token = token;
> + token = strtok(NULL, delimiter);
> + }
> +
> + return output_path;
> +}
> +
> +static void path_of(const char *full_path, char *path)
> +{
> + const char *last_slash = strrchr(full_path, '/');
> + size_t path_length;
> + char cwd[MAX_BUF];
> +
> + if (!last_slash) {
> + if (getcwd(cwd, sizeof(cwd)))
> + strcpy(path, cwd);
> + else
> + strcpy(path, ".");
> + } else {
> + path_length = last_slash - full_path;
> + strncpy(path, full_path, path_length);
> + path[path_length] = '\0';
> + }
> +}
> +
> +static bool file_exists(const char *file_path)
> +{
> + FILE *file;
> +
> + file = fopen(file_path, "r");
> + if (file) {
> + fclose(file);
> + return true;
> + }
> + return false;
> +}
> +
> +int addr2line_init(const char *cmd, const char *vmlinux)
> +{
> + if ((!file_exists(cmd)) || (!file_exists(vmlinux))) {
> + printf("file not found\n");
> + return 0;
> + }
> +
> + path_of(vmlinux, vmlinux_path);
> + if (pipe(a2l_in) == -1) {
> + printf("Failed to create pipe\n");
> + return 0;
> + }
> +
> + if (pipe(a2l_out) == -1) {
> + printf("Failed to create pipe\n");
> + return 0;
> + }
> +
> + addr2line_pid = fork();
> + if (addr2line_pid == -1) {
> + printf("Failed to fork process\n");
> + close(a2l_in[P_READ]);
> + close(a2l_in[P_WRITE]);
> + close(a2l_out[P_READ]);
> + close(a2l_out[P_WRITE]);
> + return 0;
> + }
> +
> + if (addr2line_pid == 0) {
> + dup2(a2l_in[P_READ], 0);
> + dup2(a2l_out[P_WRITE], 1);
> + close(a2l_in[P_WRITE]);
> + close(a2l_out[P_READ]);
> +
> + execlp(cmd, cmd, ADDR2LINE_ARGS, vmlinux, NULL);
> +
> + printf("Failed to execute addr2line command\n");
> + exit(1);
> + } else {
> + close(a2l_in[P_READ]);
> + close(a2l_out[P_WRITE]);
> + }
> +
> + a2l_stdin = fdopen(a2l_in[P_WRITE], "w");
> + if (!a2l_stdin) {
> + printf("Failed to open pipe a2l_in\n");
> + return 0;
> + }
> +
> + a2l_stdout = fdopen(a2l_out[P_READ], "r");
> + if (!a2l_stdout) {
> + printf("Failed to open pipe a2l_out\n");
> + fclose(a2l_stdin);
> + return 0;
> + }
> +
> + return 1;
> +}
> +
> +const char *remove_subdir(const char *home, const char *f_path)
> +{
> + int i = 0;
> +
> + while (*(home + i) == *(f_path + i))
> + i++;
> +
> + return (strlen(home) != i) ? NULL : f_path + i;
> +}
> +
> +char *addr2line_get_lines(uint64_t address)
> +{
> + char buf[MAX_BUF];
> +
> + fprintf(a2l_stdin, "%08lx\n", address);
> + fflush(a2l_stdin);
> +
> + if (!fgets(line, sizeof(line), a2l_stdout)) {
> + printf("Failed to read lines from addr2line\n");
> + return NULL;
> + }
> +
> + if (!fgets(line, sizeof(line), a2l_stdout)) {
> + printf("Failed to read lines from addr2line\n");
> + return NULL;
> + }
> +
> + line[strcspn(line, "\n")] = '\0';
> + strncpy(buf, line, MAX_BUF);
> + return normalize_path(buf, line);
> +}
> +
> +int addr2line_cleanup(void)
> +{
> + int status;
> +
> + if (addr2line_pid != -1) {
> + kill(addr2line_pid, SIGKILL);
> + waitpid(addr2line_pid, &status, 0);
> + fclose(a2l_stdin);
> + fclose(a2l_stdout);
> + addr2line_pid = -1;
> + }
> +
> + return 1;
> +}
> +
> +static char *find_executable(const char *command)
> +{
> + char *path_env = getenv("PATH");
> + char *executable_path;
> + char *path_copy;
> + char *path;
> + int n;
> +
> + if (!path_env)
> + return NULL;
> +
> + path_copy = strdup(path_env);
> + if (!path_copy)
> + return NULL;
> +
> + path = strtok(path_copy, ":");
> + while (path) {
> + n = snprintf(0, 0, "%s/%s", path, command);
> + executable_path = (char *)malloc(n + 1);
> + snprintf(executable_path, n + 1, "%s/%s", path, command);
> + if (access(executable_path, X_OK) == 0) {
> + free(path_copy);
> + return executable_path;
> + }
> +
> + path = strtok(NULL, ":");
> + free(executable_path);
> + executable_path = NULL;
> + }
> +
> + free(path_copy);
> + if (executable_path)
> + free(executable_path);
> + return NULL;
> +}
> +
> +const char *get_addr2line(int mode)
> +{
> + char *buf = "";
> +
> + switch (mode) {
> + case A2L_CROSS:
> + buf = getenv("CROSS_COMPILE");
> + memcpy(addr2line_cmd, buf, strlen(buf));
Dangerous code.
It is easy to cause a buffer overrun by setting a long string to CROSS_COMPILE.
I am fine with adding ADDR2LINE in the top Makefile.
> + case A2L_DEFAULT:
> + memcpy(addr2line_cmd + strlen(buf), ADDR2LINE, strlen(ADDR2LINE));
> + buf = find_executable(addr2line_cmd);
> + if (buf) {
> + memcpy(addr2line_cmd, buf, strlen(buf));
> + free(buf);
> + }
> + return addr2line_cmd;
> + case A2L_LLVM:
> + default:
> + return NULL;
> + }
> +}
> +
> +char *get_vmlinux(char *input)
> +{
> + const char *match_string1 = ".syms";
> + const char *match_string2 = ".tmp_vmlinux.kallsyms";
> + char *result = NULL;
> + char *match_pos;
> +
> + match_pos = strstr(input, match_string1);
> + if (!match_pos)
> + return NULL;
> +
> + match_pos = strstr(input, match_string2);
> + if (!match_pos)
> + return NULL;
> +
> + result = strdup(input);
> + match_pos = strstr(result, match_string1);
> + *match_pos = '\0';
> + return result;
> +}
Tedious code to compute the vmlinux name.
You can pass vmlinux from command line.
> diff --git a/scripts/kas_alias/item_list.c b/scripts/kas_alias/item_list.c
> new file mode 100644
> index 000000000000..48f2e525592a
> --- /dev/null
> +++ b/scripts/kas_alias/item_list.c
> @@ -0,0 +1,230 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <assert.h>
> +#include "item_list.h"
> +
> +#define CHECK_ORDER_BY_ADDRESS(sort_by, current, temp, op) \
> + ((sort_by) == BY_ADDRESS && (current)->addr op (temp)->addr)
> +#define CHECK_ORDER_BY_NAME(sort_by, current, temp, op) \
> + ((sort_by) == BY_NAME && strcmp((current)->symb_name, (temp)->symb_name) op 0)
> +
> +struct item *list_index[96] = {0};
> +
> +void build_index(struct item *list)
> +{
> + char current_first_letter = ' ';
> + struct item *current = list;
> +
> + while (current) {
> + if (current->symb_name[0] != current_first_letter) {
> + current_first_letter = current->symb_name[0];
> + list_index[current_first_letter - 32] = current;
> + }
> + current = current->next;
> + }
> +}
> +
> +struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr)
> +{
> + struct item *new_item;
> + struct item *current;
> +
> + new_item = malloc(sizeof(struct item));
> + if (!new_item)
> + return NULL;
> +
> + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> + new_item->addr = addr;
> + new_item->stype = stype;
> + new_item->next = NULL;
> +
> + if (!(*list)) {
> + *list = new_item;
> + } else {
> + current = *list;
> + while (current->next)
> + current = current->next;
What is the purpose of the ->next traverse in while() loop?
If you remember the last item,
you know where the new item should be connected, don't you?
> +struct item *merge(struct item *left, struct item *right, int sort_by)
> +{
> + struct item *current = NULL;
> + struct item *result = NULL;
> +
> + if (!left)
> + return right;
> + if (!right)
> + return left;
> +
> + if (sort_by == BY_NAME) {
> + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> + result = left;
> + left = left->next;
> + } else {
> + result = right;
> + right = right->next;
> + }
> + } else {
> + if (sort_by == BY_ADDRESS) {
> + if (left->addr <= right->addr) {
> + result = left;
> + left = left->next;
> + } else {
> + result = right;
> + right = right->next;
> + }
> + }
> + }
> +
> + current = result;
> +
> + while (left && right) {
> + if (sort_by == BY_NAME) {
> + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> + current->next = left;
> + left = left->next;
> + } else {
> + current->next = right;
> + right = right->next;
> + }
> + } else {
> + if (sort_by == BY_ADDRESS) {
> + if (left->addr <= right->addr) {
> + current->next = left;
> + left = left->next;
> + } else {
> + current->next = right;
> + right = right->next;
> + }
> + }
> + }
> +
> + current = current->next;
> + }
> +
> + if (left) {
> + current->next = left;
> + } else {
> + if (right)
> + current->next = right;
> + }
> +
> + return result;
> +}
> +
> +struct item *merge_sort(struct item *head, int sort_by)
Any reason why you did not use qsort() in the C library?
One disadvantage of quick sort is that it is not "stable sort".
But, your algorithm (sort by name and sort by address)
does not keep the order anyway.
> diff --git a/scripts/kas_alias/item_list.h b/scripts/kas_alias/item_list.h
> new file mode 100644
> index 000000000000..b4891cb088ee
> --- /dev/null
> +++ b/scripts/kas_alias/item_list.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef ITEM_LIST_H
> +#define ITEM_LIST_H
> +#include <stdint.h>
> +
> +#define MAX_NAME_SIZE 256
> +#define BY_ADDRESS 1
> +#define BY_NAME 2
> +
> +struct item {
> + char symb_name[MAX_NAME_SIZE];
> + uint64_t addr;
> + char stype;
> + struct item *next;
> +};
> +
> +void build_index(struct item *list);
> +struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr);
> +void sort_list(struct item **list, int sort_by);
> +struct item *merge(struct item *left, struct item *right, int sort_by);
> +struct item *merge_sort(struct item *head, int sort_by);
> +void sort_list_m(struct item **head, int sort_by);
> +int insert_after(struct item *list, const uint64_t search_addr,
> + const char *name, uint64_t addr, char stype);
> +void free_items(struct item **head);
> +#endif
> diff --git a/scripts/kas_alias/kas_alias.c b/scripts/kas_alias/kas_alias.c
> new file mode 100644
> index 000000000000..532aeb39f851
> --- /dev/null
> +++ b/scripts/kas_alias/kas_alias.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <stdarg.h>
> +#include <regex.h>
> +
> +#include "item_list.h"
> +#include "duplicates_list.h"
> +#include "a2l.h"
> +
> +#define SYMB_IS_TEXT(s) ((((s)->stype) == 't') || (((s)->stype) == 'T'))
> +#define SYMB_IS_DATA(s) ((((s)->stype) == 'b') || (((s)->stype) == 'B') || \
> + (((s)->stype) == 'd') || (((s)->stype) == 'D') || \
> + (((s)->stype) == 'r') || (((s)->stype) == 'R'))
> +#ifdef CONFIG_KALLSYMS_ALIAS_DATA
Please do not use #ifdef CONFIG_ in host programs.
Also, please note include/linux/kconfig.h is not included
for host programs, so this #ifdef is always false.
You never tested this CONFIG_KALLSYMS_ALIAS_DATA
> +#define SYMB_NEEDS_ALIAS(s) (SYMB_IS_TEXT(s) || SYMB_IS_DATA(s))
> +#else
> +#define SYMB_NEEDS_ALIAS(s) SYMB_IS_TEXT(s)
> +#endif
> +#define FNOMATCH 0
> +#define FMATCH 1
> +#define EREGEX 2
> +
> +const char *ignore_regex[] = {
> + "^__cfi_.*$", // __cfi_ preamble
> +#ifndef CONFIG_KALLSYMS_ALIAS_DATA_ALL
> + "^_*TRACE_SYSTEM.*$",
> + "^__already_done\\.[0-9]+$", // Call a function once data
> + "^___tp_str\\.[0-9]+$",
> + "^___done\\.[0-9]+$",
> + "^__print_once\\.[0-9]+$",
> + "^_rs\\.[0-9]+$",
> + "^__compound_literal\\.[0-9]+$",
> + "^___once_key\\.[0-9]+$",
> + "^__func__\\.[0-9]+$",
> + "^__msg\\.[0-9]+$",
> + "^CSWTCH\\.[0-9]+$",
> + "^__flags\\.[0-9]+$",
> + "^__wkey.*$",
> + "^__mkey.*$",
> + "^__key.*$",
> +#endif
> + "^__pfx_.*$" // NOP-padding
> +};
> +
> +int suffix_serial;
> +
> +static inline void verbose_msg(bool verbose, const char *fmt, ...)
Meaningless 'inline'. Only 'static' is enough.
> +{
> + va_list args;
> +
> + va_start(args, fmt);
> + if (verbose)
> + printf(fmt, args);
You cannot pass va_list to printf().
The correct code is:
vprintf(fmt, args);
> +
> + va_end(args);
> +}
verbose_msg() prints the message to stdout.
If verbose_msge is enabled, the output file breaks
because you redirect both real data and debug messages
in this way:
scripts/kas_alias/kas_alias <input> > <output>
If you implement debug logging, I recommend this:
scripts/kas_alias/kas_alias <input> <output>
> +
> +static void create_suffix(const char *name, char *output_suffix)
> +{
> + sprintf(output_suffix, "%s__alias__%d", name, suffix_serial++);
> +}
> +
> +static void create_file_suffix(const char *name, uint64_t address, char *output_suffix, char *cwd)
> +{
> + const char *f_path;
> + char *buf;
> + int i = 0;
> +
> + buf = addr2line_get_lines(address);
> + f_path = remove_subdir(cwd, buf);
> + if (f_path) {
> + sprintf(output_suffix, "%s@%s", name, f_path);
> + while (*(output_suffix + i) != '\0') {
> + switch (*(output_suffix + i)) {
> + case '/':
> + case ':':
> + case '.':
> + *(output_suffix + i) = '_';
> + break;
> + default:
> + }
> + i++;
> + }
> + } else {
> + create_suffix(name, output_suffix);
> + }
> +}
> +
> +static int filter_symbols(char *symbol, const char **ignore_list, int regex_no)
> +{
> + regex_t regex;
> + int res, i;
> +
> + for (i = 0; i < regex_no; i++) {
> + res = regcomp(®ex, ignore_list[i], REG_EXTENDED);
> + if (res)
> + return -EREGEX;
> +
> + res = regexec(®ex, symbol, 0, NULL, 0);
> + regfree(®ex);
> + switch (res) {
> + case 0:
> + return FMATCH;
> + case REG_NOMATCH:
> + break;
> + default:
> + return -EREGEX;
> + }
> + }
> +
> + return FNOMATCH;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + char t, sym_name[MAX_NAME_SIZE], new_name[MAX_NAME_SIZE + 15];
> + struct duplicate_item *duplicate_iterator;
> + struct duplicate_item *duplicate;
> + struct item *head = {NULL};
This might be something new I should learn.
When I initialize a pointer, I always write like this:
struct item *head = NULL;
I have never seen this style before:
struct item *head = {NULL};
But, the compiler does not warn about it.
Could you educate me how it works?
> + bool need_2_process = true;
> + struct item *last = {NULL};
> + struct item *current;
> + int verbose_mode = 0;
> + uint64_t address;
> + FILE *fp;
> + int res;
> +
> + if (argc < 2 || argc > 3) {
> + printf("Usage: %s <nmfile> [-verbose]\n", argv[0]);
> + return 1;
> + }
> +
> + if (argc == 3 && strcmp(argv[2], "-verbose") == 0)
"-v" or "--verbose" is better
(although there is no way to enable it.)
Anyway, I only see super-boring messages
even with -verbose given.
Scanning nm data()
Sorting nm data
Scanning nm data for duplicates
Applying suffixes
> + verbose_mode = 1;
> +
> + verbose_msg(verbose_mode, "Scanning nm data(%s)\n", argv[1]);
> +
> + fp = fopen(argv[1], "r");
> + if (!fp) {
> + printf("Can't open input file.\n");
> + return 1;
> + }
> +
> + if (!addr2line_init(get_addr2line(A2L_DEFAULT), get_vmlinux(argv[1])))
> + return 1;
> +
> + while (fscanf(fp, "%lx %c %99s\n", &address, &t, sym_name) == 3) {
> + if (strstr(sym_name, "@_")) {
> + if (verbose_mode && need_2_process)
> + printf("Already processed\n");
> + need_2_process = false;
> + }
> + last = add_item(&last, sym_name, t, address);
> + if (!last) {
> + printf("Error in allocate memory\n");
> + free_items(&head);
> + return 1;
> + }
> +
> + if (!head)
> + head = last;
> + }
> +
> + fclose(fp);
> +
> + if (need_2_process) {
> + verbose_msg(verbose_mode, "Sorting nm data\n");
> + sort_list_m(&head, BY_NAME);
> + verbose_msg(verbose_mode, "Scanning nm data for duplicates\n");
> + duplicate = find_duplicates(head);
> + if (!duplicate) {
> + printf("Error in duplicates list\n");
> + return 1;
> + }
> +
> + verbose_msg(verbose_mode, "Applying suffixes\n");
> + build_index(head);
> + duplicate_iterator = duplicate;
> + while (duplicate_iterator) {
> + res = filter_symbols(duplicate_iterator->original_item->symb_name,
> + ignore_regex, sizeof(ignore_regex) /
> + sizeof(ignore_regex[0]));
> + if (res != FMATCH &&
> + SYMB_NEEDS_ALIAS(duplicate_iterator->original_item)) {
> + if (res < 0)
> + return 1;
> +
> + create_file_suffix(duplicate_iterator->original_item->symb_name,
> + duplicate_iterator->original_item->addr,
> + new_name, vmlinux_path);
> + if (!insert_after(head, duplicate_iterator->original_item->addr,
> + new_name, duplicate_iterator->original_item->addr,
> + duplicate_iterator->original_item->stype))
> + return 1;
> + }
> +
> + duplicate_iterator = duplicate_iterator->next;
> + }
> +
> + sort_list_m(&head, BY_ADDRESS);
Do you sort just for finding duplicates?
Since you sort the list by name, and then sort by address.
It can potentially change the order.
[input]
00000000 D foo
00000000 D bar
00000010 D baz
[merge sort by name]
00000000 D bar
00000010 D baz
00000000 D foo
[merge sort by address = final result]
00000000 D bar
00000000 D foo
00000010 D baz
It may not be a big deal, but such a destructive algorithm is frowned.
You do not need to sort the list to find duplicates.
Another choice is a hashtable of { name : count }.
Traversing the list, you can count the number of occurrences.
If count >= 2, it is duplicated.
The average look-up of a hashtable is O(1).
So, the hashtable (or set) algorithm is O(N).
Sorting is O(N log N).
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index a432b171be82..cacf60b597ce 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -89,8 +89,9 @@ vmlinux_link()
>
> ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
>
> - # The kallsyms linking does not need debug symbols included.
> - if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> + # The kallsyms linking does not need debug symbols included, unless the KALLSYMS_ALIAS.
> + if [ ! is_enabled CONFIG_KALLSYMS_ALIAS ] && \
I observed this error message:
scripts/link-vmlinux.sh: 93: [: is_enabled: unexpected operator
The correct code is this:
if ! is_enabled CONFIG_KALLSYMS_ALIAS && \
> + [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> ldflags="${ldflags} ${wl}--strip-debug"
> fi
>
> @@ -161,7 +162,11 @@ kallsyms()
> fi
>
> info KSYMS ${2}
> - scripts/kallsyms ${kallsymopt} ${1} > ${2}
> + if is_enabled CONFIG_KALLSYMS_ALIAS; then
> + ALIAS=".alias"
> + scripts/kas_alias/kas_alias ${1} >${1}${ALIAS}
> + fi
> + scripts/kallsyms ${kallsymopt} ${1}${ALIAS} > ${2}
> }
>
> # Perform one step in kallsyms generation, including temporary linking of
> --
> 2.34.1
>
--
Best Regards
Masahiro Yamada
On Mon, Aug 28, 2023 at 8:45 PM Alessandro Carminati (Red Hat)
<[email protected]> wrote:
>
> From: Alessandro Carminati <[email protected]>
>
> It is not uncommon for drivers or modules related to similar peripherals
> to have symbols with the exact same name.
> While this is not a problem for the kernel's binary itself, it becomes an
> issue when attempting to trace or probe specific functions using
> infrastructure like ftrace or kprobe.
>
> The tracing subsystem relies on the `nm -n vmlinux` output, which provides
> symbol information from the kernel's ELF binary. However, when multiple
> symbols share the same name, the standard nm output does not differentiate
> between them. This can lead to confusion and difficulty when trying to
> probe the intended symbol.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff8c4f76d0 t name_show
> ffffffff8c9cccb0 t name_show
> ffffffff8cb0ac20 t name_show
> ffffffff8cc728c0 t name_show
> ffffffff8ce0efd0 t name_show
> ffffffff8ce126c0 t name_show
> ffffffff8ce1dd20 t name_show
> ffffffff8ce24e70 t name_show
> ffffffff8d1104c0 t name_show
> ffffffff8d1fe480 t name_show
>
> **kas_alias** addresses this challenge by extending the symbol names with
> unique suffixes during the kernel build process.
> The newly created aliases for these duplicated symbols are unique names
> that can be fed to the ftracefs interface. By doing so, it enables
> previously unreachable symbols to be probed.
>
> ~ # cat /proc/kallsyms | grep " name_show"
> ffffffff974f76d0 t name_show
> ffffffff974f76d0 t name_show__alias__6340
> ffffffff979cccb0 t name_show
> ffffffff979cccb0 t name_show__alias__6341
> ffffffff97b0ac20 t name_show
> ffffffff97b0ac20 t name_show__alias__6342
> ffffffff97c728c0 t name_show
> ffffffff97c728c0 t name_show__alias__6343
> ffffffff97e0efd0 t name_show
> ffffffff97e0efd0 t name_show__alias__6344
> ffffffff97e126c0 t name_show
> ffffffff97e126c0 t name_show__alias__6345
> ffffffff97e1dd20 t name_show
> ffffffff97e1dd20 t name_show__alias__6346
> ffffffff97e24e70 t name_show
> ffffffff97e24e70 t name_show__alias__6347
> ffffffff981104c0 t name_show
> ffffffff981104c0 t name_show__alias__6348
> ffffffff981fe480 t name_show
> ffffffff981fe480 t name_show__alias__6349
> ~ # echo "p:kprobes/evnt1 name_show__alias__6349" \
> > >/sys/kernel/tracing/kprobe_events
> ~ # cat /sys/kernel/tracing/kprobe_events
> p:kprobes/evnt1 name_show__alias__6349
>
> Changes from v1:
> - Integrated changes requested by Masami to exclude symbols with prefixes
> "_cfi" and "_pfx".
> - Introduced a small framework to handle patterns that need to be excluded
> from the alias production.
> - Excluded other symbols using the framework.
> - Introduced the ability to discriminate between text and data symbols.
> - Added two new config symbols in this version: CONFIG_KALLSYMS_ALIAS_DATA,
> which allows data for data, and CONFIG_KALLSYMS_ALIAS_DATA_ALL, which
> excludes all filters and provides an alias for each duplicated symbol.
>
> https://lore.kernel.org/all/[email protected]/
>
> Changes from v2:
> - Alias tags are created by querying DWARF information from the vmlinux.
> - The filename + line number is normalized and appended to the original name.
> - The tag begins with '@' to indicate the symbol source.
> - Not a change, but worth mentioning, since the alias is added to the existing
> list, the old duplicated name is preserved, and the livepatch way of dealing
> with duplicates is maintained.
> - Acknowledging the existence of scenarios where inlined functions declared in
> header files may result in multiple copies due to compiler behavior, though
> it is not actionable as it does not pose an operational issue.
> - Highlighting a single exception where the same name refers to different
> functions: the case of "compat_binfmt_elf.c," which directly includes
> "binfmt_elf.c" producing identical function copies in two separate
> modules.
>
> sample from new v3
>
> ~ # cat /proc/kallsyms | grep gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq
> ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> ffffd0b03c050960 t gic_mask_irq
> ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
> ~ #
>
> https://lore.kernel.org/all/[email protected]/
>
> Signed-off-by: Alessandro Carminati (Red Hat) <[email protected]>
> ---
> init/Kconfig | 36 ++++
> scripts/Makefile | 4 +
> scripts/kas_alias/Makefile | 4 +
> scripts/kas_alias/a2l.c | 268 ++++++++++++++++++++++++++++
> scripts/kas_alias/a2l.h | 32 ++++
> scripts/kas_alias/duplicates_list.c | 70 ++++++++
> scripts/kas_alias/duplicates_list.h | 15 ++
> scripts/kas_alias/item_list.c | 230 ++++++++++++++++++++++++
> scripts/kas_alias/item_list.h | 26 +++
> scripts/kas_alias/kas_alias.c | 217 ++++++++++++++++++++++
> scripts/link-vmlinux.sh | 11 +-
> 11 files changed, 910 insertions(+), 3 deletions(-)
I added some review comments in another thread, but
one of the biggest concerns might be "910 insertions".
What this program does is quite simple,
"find duplicated names, and call addr2line".
You wrote a lot of code to self-implement these:
- sort function
- parse PATH env variable to find addr2line
- fork addr2line to establish pipe communications
Have you considered writing the code in Python (or Perl)?
Is it too slow?
Most of the functions you implemented are already
available in script languages.
I am not sure if "@<file-path>" is a good solution,
but the amount of the added code looks too much to me.
--
Best Regards
Masahiro Yamada
On Sat, 2 Sep 2023 09:26:59 +0200
Alessandro Carminati <[email protected]> wrote:
> Hey Masami,
> Thanks a lot for your review and for your time.
>
> Il giorno mer 30 ago 2023 alle ore 08:00 Masami Hiramatsu
> <[email protected]> ha scritto:
> >
> > Hi Alessandro,
> >
> > Thanks for your update!
> >
> > On Mon, 28 Aug 2023 08:04:23 +0000
> > "Alessandro Carminati (Red Hat)" <[email protected]> wrote:
> >
> > > From: Alessandro Carminati <[email protected]>
> > >
> > > It is not uncommon for drivers or modules related to similar peripherals
> > > to have symbols with the exact same name.
> > > While this is not a problem for the kernel's binary itself, it becomes an
> > > issue when attempting to trace or probe specific functions using
> > > infrastructure like ftrace or kprobe.
> > >
> > > The tracing subsystem relies on the `nm -n vmlinux` output, which provides
> > > symbol information from the kernel's ELF binary. However, when multiple
> > > symbols share the same name, the standard nm output does not differentiate
> > > between them. This can lead to confusion and difficulty when trying to
> > > probe the intended symbol.
> > >
> > > ~ # cat /proc/kallsyms | grep " name_show"
> > > ffffffff8c4f76d0 t name_show
> > > ffffffff8c9cccb0 t name_show
> > > ffffffff8cb0ac20 t name_show
> > > ffffffff8cc728c0 t name_show
> > > ffffffff8ce0efd0 t name_show
> > > ffffffff8ce126c0 t name_show
> > > ffffffff8ce1dd20 t name_show
> > > ffffffff8ce24e70 t name_show
> > > ffffffff8d1104c0 t name_show
> > > ffffffff8d1fe480 t name_show
> > >
> > > **kas_alias** addresses this challenge by extending the symbol names with
> > > unique suffixes during the kernel build process.
> > > The newly created aliases for these duplicated symbols are unique names
> > > that can be fed to the ftracefs interface. By doing so, it enables
> > > previously unreachable symbols to be probed.
> > >
> > > ~ # cat /proc/kallsyms | grep " name_show"
> > > ffffffff974f76d0 t name_show
> > > ffffffff974f76d0 t name_show__alias__6340
> > > ffffffff979cccb0 t name_show
> > > ffffffff979cccb0 t name_show__alias__6341
> > > ffffffff97b0ac20 t name_show
> > > ffffffff97b0ac20 t name_show__alias__6342
> > > ffffffff97c728c0 t name_show
> > > ffffffff97c728c0 t name_show__alias__6343
> > > ffffffff97e0efd0 t name_show
> > > ffffffff97e0efd0 t name_show__alias__6344
> > > ffffffff97e126c0 t name_show
> > > ffffffff97e126c0 t name_show__alias__6345
> > > ffffffff97e1dd20 t name_show
> > > ffffffff97e1dd20 t name_show__alias__6346
> > > ffffffff97e24e70 t name_show
> > > ffffffff97e24e70 t name_show__alias__6347
> > > ffffffff981104c0 t name_show
> > > ffffffff981104c0 t name_show__alias__6348
> > > ffffffff981fe480 t name_show
> > > ffffffff981fe480 t name_show__alias__6349
> > > ~ # echo "p:kprobes/evnt1 name_show__alias__6349" \
> > > > >/sys/kernel/tracing/kprobe_events
> > > ~ # cat /sys/kernel/tracing/kprobe_events
> > > p:kprobes/evnt1 name_show__alias__6349
> > >
> > > Changes from v1:
> > > - Integrated changes requested by Masami to exclude symbols with prefixes
> > > "_cfi" and "_pfx".
> > > - Introduced a small framework to handle patterns that need to be excluded
> > > from the alias production.
> > > - Excluded other symbols using the framework.
> > > - Introduced the ability to discriminate between text and data symbols.
> > > - Added two new config symbols in this version: CONFIG_KALLSYMS_ALIAS_DATA,
> > > which allows data for data, and CONFIG_KALLSYMS_ALIAS_DATA_ALL, which
> > > excludes all filters and provides an alias for each duplicated symbol.
> > >
> > > https://lore.kernel.org/all/[email protected]/
> > >
> > > Changes from v2:
> > > - Alias tags are created by querying DWARF information from the vmlinux.
> > > - The filename + line number is normalized and appended to the original name.
> > > - The tag begins with '@' to indicate the symbol source.
> > > - Not a change, but worth mentioning, since the alias is added to the existing
> > > list, the old duplicated name is preserved, and the livepatch way of dealing
> > > with duplicates is maintained.
> > > - Acknowledging the existence of scenarios where inlined functions declared in
> > > header files may result in multiple copies due to compiler behavior, though
> > > it is not actionable as it does not pose an operational issue.
> > > - Highlighting a single exception where the same name refers to different
> > > functions: the case of "compat_binfmt_elf.c," which directly includes
> > > "binfmt_elf.c" producing identical function copies in two separate
> > > modules.
> > >
> > > sample from new v3
> > >
> > > ~ # cat /proc/kallsyms | grep gic_mask_irq
> > > ffffd0b03c04dae4 t gic_mask_irq
> > > ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> > > ffffd0b03c050960 t gic_mask_irq
> > > ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
> >
> > Could you also update the sample output in the patch description?
> > And I can not see this line information but a serial number aliases,
> > is there any way to enable this file-name aliases? (LLVM is not supported?)
> > I think we'd better to have a new CONFIG_KALLSYMS_ALIAS_SRCLINE and
> > clarify what is required.
>
> In this version of the patch, there's still a fallback action that
> produces the old "__alias__<seqnum>" if the addr2line action fails.
> In the v3 patch, addr2line is default to the native option.
OK, do you know when the addr2line fails? If it is clear, it is
better to unselect the CONFIG_KALLSYMS_ALIAS_SRCLINE instead of
statically failback to seqnum suffix (or failed to build), because
user expects that the built kernel image is including the alias has
suffixes based on src line number.
This is important especially it depends on user environment, because
it gives user to update their environment before building the kernel.
> The CROSS_COMPILE setting remains a manual selection. While in my tests,
> I didn't encounter any issues, and the native addr2line worked well on
> all the architectures I tested, there is still a possibility of failure
> leading to the fallback action. Somthing I will change in the v4.
Good.
>
> Additionally, if CONFIG_KALLSYMS_ALIAS_DATA is set to 'Y,' data names
> included in the KALLSYMS receive an old-style alias.
> Regarding this matter, I'd like to discuss with you the relevance of
> CONFIG_KALLSYMS_ALIAS_DATA and CONFIG_KALLSYMS_ALIAS_DATA_ALL.
Would you mean that the symbols of DATA can not use src lines?
(what is the "old-style alias" you meant here?)
> Both of these settings aim to provide an alias for variable names as
> well. In the past, I had to "livepatch" a function for an architecture
> that had no support, and I thought it would be beneficial to have
> unique variable names as well. What are your thoughts on this?
Yeah, it is also good for kprobe-events because it supports probes
to access global variables by name. Thus if the alias can specify a
unique symbol, it ensures which variable we will trace.
> >
> > > ~ #
> > >
> > > https://lore.kernel.org/all/[email protected]/
> > >
> > > Signed-off-by: Alessandro Carminati (Red Hat) <[email protected]>
> > > ---
> > > init/Kconfig | 36 ++++
> > > scripts/Makefile | 4 +
> > > scripts/kas_alias/Makefile | 4 +
> > > scripts/kas_alias/a2l.c | 268 ++++++++++++++++++++++++++++
> > > scripts/kas_alias/a2l.h | 32 ++++
> > > scripts/kas_alias/duplicates_list.c | 70 ++++++++
> > > scripts/kas_alias/duplicates_list.h | 15 ++
> > > scripts/kas_alias/item_list.c | 230 ++++++++++++++++++++++++
> > > scripts/kas_alias/item_list.h | 26 +++
> > > scripts/kas_alias/kas_alias.c | 217 ++++++++++++++++++++++
> > > scripts/link-vmlinux.sh | 11 +-
> > > 11 files changed, 910 insertions(+), 3 deletions(-)
> > > create mode 100644 scripts/kas_alias/Makefile
> > > create mode 100644 scripts/kas_alias/a2l.c
> > > create mode 100644 scripts/kas_alias/a2l.h
> > > create mode 100644 scripts/kas_alias/duplicates_list.c
> > > create mode 100644 scripts/kas_alias/duplicates_list.h
> > > create mode 100644 scripts/kas_alias/item_list.c
> > > create mode 100644 scripts/kas_alias/item_list.h
> > > create mode 100644 scripts/kas_alias/kas_alias.c
> > >
> > > diff --git a/init/Kconfig b/init/Kconfig
> > > index f7f65af4ee12..bc69fcd9cbc8 100644
> > > --- a/init/Kconfig
> > > +++ b/init/Kconfig
> > > @@ -1737,6 +1737,42 @@ config KALLSYMS_BASE_RELATIVE
> > > time constants, and no relocation pass is required at runtime to fix
> > > up the entries based on the runtime load address of the kernel.
> > >
> > > +config KALLSYMS_ALIAS
> > > + bool "Produces alias for duplicated symbols" if EXPERT
> > > + depends on KALLSYMS && (DEBUG_INFO_DWARF4 || DEBUG_INFO_DWARF5)
> > > + help
> > > + It is not uncommon for drivers or modules related to similar
> > > + peripherals to have symbols with the exact same name.
> > > + While this is not a problem for the kernel's binary itself, it
> > > + becomes an issue when attempting to trace or probe specific
> > > + functions using infrastructure like ftrace or kprobe.
> > > +
> > > + This option addresses this challenge by extending the symbol names
> > > + with unique suffixes during the kernel build process.
> > > + The newly created aliases for these duplicated symbols are unique
> > > + names that can be fed to the ftrace sysfs interface. By doing so, it
> > > + enables previously unreachable symbols to be probed.
> > > +
> > > +config CONFIG_KALLSYMS_ALIAS_DATA
> >
> > You don't need 'CONFIG_' prefix here.
> >
> > > + bool "Produces alias also for data"
> > > + depends on KALLSYMS_ALIAS
> > > + help
> > > + Sometimes it can be useful to refer to data. In live patch scenarios,
> > > + you may find yourself needing to use symbols that are shared with
> > > + other functions. Since symbols face the same issue as functions, this
> > > + option allows you to create aliases for data as well.
> > > +
> > > +config CONFIG_KALLSYMS_ALIAS_DATA_ALL
> > > + bool "Removes all filter when producing data alias"
> > > + depends on CONFIG_KALLSYMS_ALIAS_DATA
> > > + help
> > > + When selecting data aliases, not all symbols are included in the set
> > > + This is because many symbols are unlikely to be used. If you choose
> > > + to have an alias for all data symbols, be aware that it will
> > > + significantly increase the size.
> > > +
> > > + If unsure, say N.
> > > +
> > > # end of the "standard kernel features (expert users)" menu
> > >
> > > # syscall, maps, verifier
> > > diff --git a/scripts/Makefile b/scripts/Makefile
> > > index 32b6ba722728..65fafe17cfe5 100644
> > > --- a/scripts/Makefile
> > > +++ b/scripts/Makefile
> > > @@ -49,3 +49,7 @@ subdir-$(CONFIG_SECURITY_SELINUX) += selinux
> > >
> > > # Let clean descend into subdirs
> > > subdir- += basic dtc gdb kconfig mod
> > > +
> > > +# KALLSyms alias
> > > +subdir-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
> > > +
> > > diff --git a/scripts/kas_alias/Makefile b/scripts/kas_alias/Makefile
> > > new file mode 100644
> > > index 000000000000..e1fde69232b4
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/Makefile
> > > @@ -0,0 +1,4 @@
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +hostprogs-always-$(CONFIG_KALLSYMS_ALIAS) += kas_alias
> > > +
> > > +kas_alias-objs := duplicates_list.o item_list.o kas_alias.o a2l.o
> > > diff --git a/scripts/kas_alias/a2l.c b/scripts/kas_alias/a2l.c
> > > new file mode 100644
> > > index 000000000000..a9692ac30180
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/a2l.c
> > > @@ -0,0 +1,268 @@
> > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <string.h>
> > > +#include <unistd.h>
> > > +#include <sys/types.h>
> > > +#include <sys/wait.h>
> > > +#include <string.h>
> > > +#include <stdint.h>
> > > +#include <stdbool.h>
> > > +
> > > +#include "a2l.h"
> > > +
> > > +int addr2line_pid = -1;
> > > +int a2l_in[2];
> > > +int a2l_out[2];
> > > +char line[MAX_BUF];
> > > +char vmlinux_path[MAX_BUF];
> > > +char addr2line_cmd[MAX_CMD_LEN];
> > > +FILE *a2l_stdin, *a2l_stdout;
> > > +
> > > +static char *normalize_path(const char *input_path, char *output_path)
> > > +{
> > > + char *prev_token = NULL;
> > > + char *delimiter = "/";
> > > + char inbuf[MAX_BUF];
> > > + char *token;
> > > + char *pos;
> > > +
> > > + memset(inbuf, 0, MAX_BUF);
> > > + *output_path = '\0';
> > > + strncpy(inbuf, input_path, MAX_BUF);
> > > + if (!input_path || !output_path || strlen(input_path) == 0)
> > > + return NULL;
> > > +
> > > + token = strtok(inbuf, delimiter);
> > > + while (token) {
> > > + if (strcmp(token, "..") == 0 && prev_token) {
> > > + pos = strrchr(output_path, '/');
> > > + if (pos)
> > > + *pos = '\0';
> > > +
> > > + } else if (strcmp(token, ".") != 0) {
> > > + strcat(output_path, "/");
> > > + strcat(output_path, token);
> > > + }
> > > +
> > > + prev_token = token;
> > > + token = strtok(NULL, delimiter);
> > > + }
> > > +
> > > + return output_path;
> > > +}
> > > +
> > > +static void path_of(const char *full_path, char *path)
> > > +{
> > > + const char *last_slash = strrchr(full_path, '/');
> > > + size_t path_length;
> > > + char cwd[MAX_BUF];
> > > +
> > > + if (!last_slash) {
> > > + if (getcwd(cwd, sizeof(cwd)))
> > > + strcpy(path, cwd);
> > > + else
> > > + strcpy(path, ".");
> > > + } else {
> > > + path_length = last_slash - full_path;
> > > + strncpy(path, full_path, path_length);
> > > + path[path_length] = '\0';
> > > + }
> > > +}
> > > +
> > > +static bool file_exists(const char *file_path)
> > > +{
> > > + FILE *file;
> > > +
> > > + file = fopen(file_path, "r");
> > > + if (file) {
> > > + fclose(file);
> > > + return true;
> > > + }
> > > + return false;
> > > +}
> > > +
> > > +int addr2line_init(const char *cmd, const char *vmlinux)
> > > +{
> > > + if ((!file_exists(cmd)) || (!file_exists(vmlinux))) {
> > > + printf("file not found\n");
> > > + return 0;
> > > + }
> >
> > nit: mis-indentation?
> >
> > > +
> > > + path_of(vmlinux, vmlinux_path);
> > > + if (pipe(a2l_in) == -1) {
> > > + printf("Failed to create pipe\n");
> > > + return 0;
> > > + }
> > > +
> > > + if (pipe(a2l_out) == -1) {
> > > + printf("Failed to create pipe\n");
> > > + return 0;
> > > + }
> > > +
> > > + addr2line_pid = fork();
> > > + if (addr2line_pid == -1) {
> > > + printf("Failed to fork process\n");
> > > + close(a2l_in[P_READ]);
> > > + close(a2l_in[P_WRITE]);
> > > + close(a2l_out[P_READ]);
> > > + close(a2l_out[P_WRITE]);
> > > + return 0;
> > > + }
> > > +
> > > + if (addr2line_pid == 0) {
> > > + dup2(a2l_in[P_READ], 0);
> > > + dup2(a2l_out[P_WRITE], 1);
> > > + close(a2l_in[P_WRITE]);
> > > + close(a2l_out[P_READ]);
> > > +
> > > + execlp(cmd, cmd, ADDR2LINE_ARGS, vmlinux, NULL);
> > > +
> > > + printf("Failed to execute addr2line command\n");
> > > + exit(1);
> > > + } else {
> > > + close(a2l_in[P_READ]);
> > > + close(a2l_out[P_WRITE]);
> > > + }
> > > +
> > > + a2l_stdin = fdopen(a2l_in[P_WRITE], "w");
> > > + if (!a2l_stdin) {
> > > + printf("Failed to open pipe a2l_in\n");
> > > + return 0;
> > > + }
> > > +
> > > + a2l_stdout = fdopen(a2l_out[P_READ], "r");
> > > + if (!a2l_stdout) {
> > > + printf("Failed to open pipe a2l_out\n");
> > > + fclose(a2l_stdin);
> > > + return 0;
> > > + }
> > > +
> > > + return 1;
> > > +}
> > > +
> > > +const char *remove_subdir(const char *home, const char *f_path)
> > > +{
> > > + int i = 0;
> > > +
> > > + while (*(home + i) == *(f_path + i))
> > > + i++;
> > > +
> > > + return (strlen(home) != i) ? NULL : f_path + i;
> > > +}
> > > +
> > > +char *addr2line_get_lines(uint64_t address)
> > > +{
> > > + char buf[MAX_BUF];
> > > +
> > > + fprintf(a2l_stdin, "%08lx\n", address);
> > > + fflush(a2l_stdin);
> > > +
> > > + if (!fgets(line, sizeof(line), a2l_stdout)) {
> > > + printf("Failed to read lines from addr2line\n");
> > > + return NULL;
> > > + }
> > > +
> > > + if (!fgets(line, sizeof(line), a2l_stdout)) {
> > > + printf("Failed to read lines from addr2line\n");
> > > + return NULL;
> > > + }
> > > +
> > > + line[strcspn(line, "\n")] = '\0';
> > > + strncpy(buf, line, MAX_BUF);
> > > + return normalize_path(buf, line);
> > > +}
> > > +
> > > +int addr2line_cleanup(void)
> > > +{
> > > + int status;
> > > +
> > > + if (addr2line_pid != -1) {
> > > + kill(addr2line_pid, SIGKILL);
> > > + waitpid(addr2line_pid, &status, 0);
> > > + fclose(a2l_stdin);
> > > + fclose(a2l_stdout);
> > > + addr2line_pid = -1;
> > > + }
> > > +
> > > + return 1;
> > > +}
> > > +
> > > +static char *find_executable(const char *command)
> > > +{
> > > + char *path_env = getenv("PATH");
> > > + char *executable_path;
> > > + char *path_copy;
> > > + char *path;
> > > + int n;
> > > +
> > > + if (!path_env)
> > > + return NULL;
> > > +
> > > + path_copy = strdup(path_env);
> > > + if (!path_copy)
> > > + return NULL;
> > > +
> > > + path = strtok(path_copy, ":");
> > > + while (path) {
> > > + n = snprintf(0, 0, "%s/%s", path, command);
> > > + executable_path = (char *)malloc(n + 1);
> > > + snprintf(executable_path, n + 1, "%s/%s", path, command);
> > > + if (access(executable_path, X_OK) == 0) {
> > > + free(path_copy);
> > > + return executable_path;
> > > + }
> > > +
> > > + path = strtok(NULL, ":");
> > > + free(executable_path);
> > > + executable_path = NULL;
> >
> > nit: mis-indentation?
> >
> > > + }
> > > +
> > > + free(path_copy);
> > > + if (executable_path)
> > > + free(executable_path);
> > > + return NULL;
> > > +}
> > > +
> > > +const char *get_addr2line(int mode)
> > > +{
> > > + char *buf = "";
> > > +
> > > + switch (mode) {
> > > + case A2L_CROSS:
> > > + buf = getenv("CROSS_COMPILE");
> > > + memcpy(addr2line_cmd, buf, strlen(buf));
> > > + case A2L_DEFAULT:
> > > + memcpy(addr2line_cmd + strlen(buf), ADDR2LINE, strlen(ADDR2LINE));
> > > + buf = find_executable(addr2line_cmd);
> > > + if (buf) {
> > > + memcpy(addr2line_cmd, buf, strlen(buf));
> > > + free(buf);
> > > + }
> > > + return addr2line_cmd;
> > > + case A2L_LLVM:
> > > + default:
> > > + return NULL;
> > > + }
> > > +}
> > > +
> > > +char *get_vmlinux(char *input)
> > > +{
> > > + const char *match_string1 = ".syms";
> > > + const char *match_string2 = ".tmp_vmlinux.kallsyms";
> > > + char *result = NULL;
> > > + char *match_pos;
> > > +
> > > + match_pos = strstr(input, match_string1);
> > > + if (!match_pos)
> > > + return NULL;
> > > +
> > > + match_pos = strstr(input, match_string2);
> > > + if (!match_pos)
> > > + return NULL;
> > > +
> > > + result = strdup(input);
> > > + match_pos = strstr(result, match_string1);
> > > + *match_pos = '\0';
> > > + return result;
> > > +}
> > > diff --git a/scripts/kas_alias/a2l.h b/scripts/kas_alias/a2l.h
> > > new file mode 100644
> > > index 000000000000..ca6419229dde
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/a2l.h
> > > @@ -0,0 +1,32 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > > +#ifndef A2L_H
> > > +#define A2L_H
> > > +#include <stdint.h>
> > > +
> > > +#define ADDR2LINE "addr2line"
> > > +#define ADDR2LINE_ARGS "-fe"
> > > +//#define VMLINUX "vmlinux"
> >
> > Nit: this should be removed if it is not used.
> >
> > > +#define MAX_BUF 4096
> > > +#define MAX_CMD_LEN 256
> > > +#define P_READ 0
> > > +#define P_WRITE 1
> > > +#define A2L_DEFAULT 1
> > > +#define A2L_CROSS 2
> > > +#define A2L_LLVM 3
> > > +#define A2L_MAKE_VALUE 2
> > > +
> > > +extern int addr2line_pid;
> > > +extern int a2l_in[2];
> > > +extern int a2l_out[2];
> > > +extern char line[MAX_BUF];
> > > +extern char vmlinux_path[MAX_BUF];
> > > +extern char addr2line_cmd[MAX_CMD_LEN];
> > > +
> > > +int addr2line_init(const char *cmd, const char *vmlinux);
> > > +char *addr2line_get_lines(uint64_t address);
> > > +int addr2line_cleanup(void);
> > > +const char *remove_subdir(const char *home, const char *f_path);
> > > +const char *get_addr2line(int mode);
> > > +char *get_vmlinux(char *input);
> > > +
> > > +#endif
> > > diff --git a/scripts/kas_alias/duplicates_list.c b/scripts/kas_alias/duplicates_list.c
> > > new file mode 100644
> > > index 000000000000..e7a3d2917937
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/duplicates_list.c
> > > @@ -0,0 +1,70 @@
> > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > +#include <stdint.h>
> > > +#include <stdio.h>
> > > +#include <string.h>
> > > +#include <stdlib.h>
> > > +#include <stdbool.h>
> > > +
> > > +#include "item_list.h"
> > > +#include "duplicates_list.h"
> > > +
> >
> > /* The item list must be sorted. */
> >
> > I think we can find the duplicated symbol without sorting the list,
> > but such implementation level optimization will be done later.
>
> I think I will handle this aspect in the v4.
Good :)
>
> >
> > > +struct duplicate_item *find_duplicates(struct item *list)
> > > +{
> > > + struct duplicate_item *current_duplicate = NULL;
> > > + struct duplicate_item *duplicates = NULL;
> > > + struct duplicate_item *new_duplicate;
> > > + struct item *current_item = list;
> > > + bool prev_was_duplicate = false;
> > > + struct item *prev_item = NULL;
> > > +
> > > + while (current_item) {
> > > + if ((prev_item && (strcmp(current_item->symb_name, prev_item->symb_name) == 0)) ||
> > > + prev_was_duplicate) {
> > > + if (!duplicates) {
> > > + duplicates = malloc(sizeof(struct duplicate_item));
> > > + if (!duplicates)
> > > + return NULL;
> > > +
> > > + duplicates->original_item = prev_item;
> > > + duplicates->next = NULL;
> > > + current_duplicate = duplicates;
> > > + } else {
> > > + new_duplicate = malloc(sizeof(struct duplicate_item));
> > > + if (!new_duplicate) {
> > > + free_duplicates(&duplicates);
> > > + return NULL;
> > > + }
> > > +
> > > + new_duplicate->original_item = prev_item;
> > > + new_duplicate->next = NULL;
> > > + current_duplicate->next = new_duplicate;
> > > + current_duplicate = new_duplicate;
> > > +
> > > + if ((strcmp(current_item->symb_name, prev_item->symb_name) != 0) &&
> > > + (prev_was_duplicate))
> > > + prev_was_duplicate = false;
> > > + else
> > > + prev_was_duplicate = true;
> > > + }
> > > + }
> > > +
> > > + prev_item = current_item;
> > > + current_item = current_item->next;
> > > + }
> > > +
> > > + return duplicates;
> > > +}
> > > +
> > > +void free_duplicates(struct duplicate_item **duplicates)
> > > +{
> > > + struct duplicate_item *duplicates_iterator = *duplicates;
> > > + struct duplicate_item *app;
> > > +
> > > + while (duplicates_iterator) {
> > > + app = duplicates_iterator;
> > > + duplicates_iterator = duplicates_iterator->next;
> > > + free(app);
> > > + }
> > > +
> > > + *duplicates = NULL;
> > > +}
> > > diff --git a/scripts/kas_alias/duplicates_list.h b/scripts/kas_alias/duplicates_list.h
> > > new file mode 100644
> > > index 000000000000..76aa73e584bc
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/duplicates_list.h
> > > @@ -0,0 +1,15 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > > +#ifndef DUPLICATES_LIST_H
> > > +#define DUPLICATES_LIST_H
> > > +
> > > +#include "item_list.h"
> > > +
> > > +struct duplicate_item {
> > > + struct item *original_item;
> > > + struct duplicate_item *next;
> > > +};
> > > +
> > > +struct duplicate_item *find_duplicates(struct item *list);
> > > +void free_duplicates(struct duplicate_item **duplicates);
> > > +
> > > +#endif
> > > diff --git a/scripts/kas_alias/item_list.c b/scripts/kas_alias/item_list.c
> > > new file mode 100644
> > > index 000000000000..48f2e525592a
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/item_list.c
> > > @@ -0,0 +1,230 @@
> > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <stdint.h>
> > > +#include <string.h>
> > > +#include <stdbool.h>
> > > +#include <assert.h>
> > > +#include "item_list.h"
> > > +
> > > +#define CHECK_ORDER_BY_ADDRESS(sort_by, current, temp, op) \
> > > + ((sort_by) == BY_ADDRESS && (current)->addr op (temp)->addr)
> > > +#define CHECK_ORDER_BY_NAME(sort_by, current, temp, op) \
> > > + ((sort_by) == BY_NAME && strcmp((current)->symb_name, (temp)->symb_name) op 0)
> > > +
> > > +struct item *list_index[96] = {0};
> > > +
> > > +void build_index(struct item *list)
> > > +{
> > > + char current_first_letter = ' ';
> > > + struct item *current = list;
> > > +
> > > + while (current) {
> > > + if (current->symb_name[0] != current_first_letter) {
> > > + current_first_letter = current->symb_name[0];
> > > + list_index[current_first_letter - 32] = current;
> > > + }
> > > + current = current->next;
> > > + }
> > > +}
> > > +
> > > +struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr)
> > > +{
> > > + struct item *new_item;
> > > + struct item *current;
> > > +
> > > + new_item = malloc(sizeof(struct item));
> > > + if (!new_item)
> > > + return NULL;
> > > +
> > > + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> > > + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> > > + new_item->addr = addr;
> > > + new_item->stype = stype;
> > > + new_item->next = NULL;
> > > +
> > > + if (!(*list)) {
> > > + *list = new_item;
> > > + } else {
> > > + current = *list;
> > > + while (current->next)
> > > + current = current->next;
> > > +
> > > + current->next = new_item;
> > > + }
> > > + return new_item;
> > > +}
> > > +
> > > +void sort_list(struct item **list, int sort_by)
> > > +{
> > > + struct item *current = *list;
> > > + struct item *sorted = NULL;
> > > + struct item *next_item;
> > > + struct item *temp;
> > > +
> > > + if (!(*list) || !((*list)->next))
> > > + return;
> > > +
> > > + while (current) {
> > > + next_item = current->next;
> > > + if (!sorted ||
> > > + (CHECK_ORDER_BY_ADDRESS(sort_by, current, sorted, <) ||
> > > + CHECK_ORDER_BY_NAME(sort_by, current, sorted, >=))) {
> > > + current->next = sorted;
> > > + sorted = current;
> > > + } else {
> > > + temp = sorted;
> > > + while (temp->next &&
> > > + (CHECK_ORDER_BY_ADDRESS(sort_by, current, temp->next, >=) ||
> > > + CHECK_ORDER_BY_NAME(sort_by, current, temp->next, >=)))
> > > + temp = temp->next;
> > > +
> > > + current->next = temp->next;
> > > + temp->next = current;
> > > + }
> > > + current = next_item;
> > > + }
> > > +
> > > + *list = sorted;
> > > +}
> > > +
> > > +struct item *merge(struct item *left, struct item *right, int sort_by)
> > > +{
> > > + struct item *current = NULL;
> > > + struct item *result = NULL;
> > > +
> > > + if (!left)
> > > + return right;
> > > + if (!right)
> > > + return left;
> > > +
> > > + if (sort_by == BY_NAME) {
> > > + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> > > + result = left;
> > > + left = left->next;
> > > + } else {
> > > + result = right;
> > > + right = right->next;
> > > + }
> > > + } else {
> > > + if (sort_by == BY_ADDRESS) {
> > > + if (left->addr <= right->addr) {
> > > + result = left;
> > > + left = left->next;
> > > + } else {
> > > + result = right;
> > > + right = right->next;
> > > + }
> > > + }
> > > + }
> > > +
> > > + current = result;
> > > +
> > > + while (left && right) {
> > > + if (sort_by == BY_NAME) {
> > > + if (strcmp(left->symb_name, right->symb_name) <= 0) {
> > > + current->next = left;
> > > + left = left->next;
> > > + } else {
> > > + current->next = right;
> > > + right = right->next;
> > > + }
> > > + } else {
> > > + if (sort_by == BY_ADDRESS) {
> > > + if (left->addr <= right->addr) {
> > > + current->next = left;
> > > + left = left->next;
> > > + } else {
> > > + current->next = right;
> > > + right = right->next;
> > > + }
> > > + }
> > > + }
> > > +
> > > + current = current->next;
> > > + }
> > > +
> > > + if (left) {
> > > + current->next = left;
> > > + } else {
> > > + if (right)
> > > + current->next = right;
> > > + }
> > > +
> > > + return result;
> > > +}
> > > +
> > > +struct item *merge_sort(struct item *head, int sort_by)
> > > +{
> > > + struct item *right;
> > > + struct item *slow;
> > > + struct item *fast;
> > > + struct item *left;
> > > +
> > > + if (!head || !head->next)
> > > + return head;
> > > +
> > > + slow = head;
> > > + fast = head->next;
> > > +
> > > + while (fast && fast->next) {
> > > + slow = slow->next;
> > > + fast = fast->next->next;
> > > + }
> > > +
> > > + left = head;
> > > + right = slow->next;
> > > + slow->next = NULL;
> > > +
> > > + left = merge_sort(left, sort_by);
> > > + right = merge_sort(right, sort_by);
> > > +
> > > + return merge(left, right, sort_by);
> > > +}
> > > +
> > > +void sort_list_m(struct item **head, int sort_by)
> > > +{
> > > + if (!(*head) || !((*head)->next))
> > > + return;
> > > +
> > > + *head = merge_sort(*head, sort_by);
> > > +}
> > > +
> > > +int insert_after(struct item *list, const uint64_t search_addr,
> > > + const char *name, uint64_t addr, char stype)
> > > +{
> > > + struct item *new_item;
> > > + struct item *current;
> > > + int ret = 0;
> > > +
> > > + current = (list_index[name[0] - 32]) ? list_index[name[0] - 32] : list;
> > > + while (current) {
> > > + if (current->addr == search_addr) {
> > > + new_item = malloc(sizeof(struct item));
> > > + if (!new_item)
> > > + return ret;
> > > + strncpy(new_item->symb_name, name, MAX_NAME_SIZE);
> > > + new_item->symb_name[MAX_NAME_SIZE - 1] = '\0';
> > > + new_item->addr = addr;
> > > + new_item->stype = stype;
> > > + new_item->next = current->next;
> > > + current->next = new_item;
> > > + ret = 1;
> > > + break;
> > > + }
> > > + current = current->next;
> > > + }
> > > + return ret;
> > > +}
> > > +
> > > +void free_items(struct item **head)
> > > +{
> > > + struct item *app, *item_iterator = *head;
> > > +
> > > + while (item_iterator) {
> > > + app = item_iterator;
> > > + item_iterator = item_iterator->next;
> > > + free(app);
> > > + }
> > > + *head = NULL;
> > > +}
> > > diff --git a/scripts/kas_alias/item_list.h b/scripts/kas_alias/item_list.h
> > > new file mode 100644
> > > index 000000000000..b4891cb088ee
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/item_list.h
> > > @@ -0,0 +1,26 @@
> > > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > > +#ifndef ITEM_LIST_H
> > > +#define ITEM_LIST_H
> > > +#include <stdint.h>
> > > +
> > > +#define MAX_NAME_SIZE 256
> > > +#define BY_ADDRESS 1
> > > +#define BY_NAME 2
> > > +
> > > +struct item {
> > > + char symb_name[MAX_NAME_SIZE];
> > > + uint64_t addr;
> > > + char stype;
> > > + struct item *next;
> > > +};
> > > +
> > > +void build_index(struct item *list);
> > > +struct item *add_item(struct item **list, const char *name, char stype, uint64_t addr);
> > > +void sort_list(struct item **list, int sort_by);
> > > +struct item *merge(struct item *left, struct item *right, int sort_by);
> > > +struct item *merge_sort(struct item *head, int sort_by);
> > > +void sort_list_m(struct item **head, int sort_by);
> > > +int insert_after(struct item *list, const uint64_t search_addr,
> > > + const char *name, uint64_t addr, char stype);
> > > +void free_items(struct item **head);
> > > +#endif
> > > diff --git a/scripts/kas_alias/kas_alias.c b/scripts/kas_alias/kas_alias.c
> > > new file mode 100644
> > > index 000000000000..532aeb39f851
> > > --- /dev/null
> > > +++ b/scripts/kas_alias/kas_alias.c
> > > @@ -0,0 +1,217 @@
> > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <stdint.h>
> > > +#include <unistd.h>
> > > +#include <string.h>
> > > +#include <stdbool.h>
> > > +#include <stdarg.h>
> > > +#include <regex.h>
> > > +
> > > +#include "item_list.h"
> > > +#include "duplicates_list.h"
> > > +#include "a2l.h"
> > > +
> > > +#define SYMB_IS_TEXT(s) ((((s)->stype) == 't') || (((s)->stype) == 'T'))
> > > +#define SYMB_IS_DATA(s) ((((s)->stype) == 'b') || (((s)->stype) == 'B') || \
> > > + (((s)->stype) == 'd') || (((s)->stype) == 'D') || \
> > > + (((s)->stype) == 'r') || (((s)->stype) == 'R'))
> > > +#ifdef CONFIG_KALLSYMS_ALIAS_DATA
> > > +#define SYMB_NEEDS_ALIAS(s) (SYMB_IS_TEXT(s) || SYMB_IS_DATA(s))
> > > +#else
> > > +#define SYMB_NEEDS_ALIAS(s) SYMB_IS_TEXT(s)
> > > +#endif
> > > +#define FNOMATCH 0
> > > +#define FMATCH 1
> > > +#define EREGEX 2
> > > +
> > > +const char *ignore_regex[] = {
> > > + "^__cfi_.*$", // __cfi_ preamble
> > > +#ifndef CONFIG_KALLSYMS_ALIAS_DATA_ALL
> > > + "^_*TRACE_SYSTEM.*$",
> > > + "^__already_done\\.[0-9]+$", // Call a function once data
> > > + "^___tp_str\\.[0-9]+$",
> > > + "^___done\\.[0-9]+$",
> > > + "^__print_once\\.[0-9]+$",
> > > + "^_rs\\.[0-9]+$",
> > > + "^__compound_literal\\.[0-9]+$",
> > > + "^___once_key\\.[0-9]+$",
> > > + "^__func__\\.[0-9]+$",
> > > + "^__msg\\.[0-9]+$",
> > > + "^CSWTCH\\.[0-9]+$",
> > > + "^__flags\\.[0-9]+$",
> > > + "^__wkey.*$",
> > > + "^__mkey.*$",
> > > + "^__key.*$",
> > > +#endif
> > > + "^__pfx_.*$" // NOP-padding
> > > +};
> > > +
> > > +int suffix_serial;
> > > +
> > > +static inline void verbose_msg(bool verbose, const char *fmt, ...)
> > > +{
> > > + va_list args;
> > > +
> > > + va_start(args, fmt);
> > > + if (verbose)
> > > + printf(fmt, args);
> > > +
> > > + va_end(args);
> > > +}
> > > +
> > > +static void create_suffix(const char *name, char *output_suffix)
> > > +{
> > > + sprintf(output_suffix, "%s__alias__%d", name, suffix_serial++);
> > > +}
> > > +
> > > +static void create_file_suffix(const char *name, uint64_t address, char *output_suffix, char *cwd)
> > > +{
> > > + const char *f_path;
> > > + char *buf;
> > > + int i = 0;
> > > +
> > > + buf = addr2line_get_lines(address);
> > > + f_path = remove_subdir(cwd, buf);
> > > + if (f_path) {
> > > + sprintf(output_suffix, "%s@%s", name, f_path);
> > > + while (*(output_suffix + i) != '\0') {
> > > + switch (*(output_suffix + i)) {
> > > + case '/':
> > > + case ':':
> > > + case '.':
> >
> > This is not enough because file path will accept more than that.
> > E.g. '+', '&', '-'.
> > So I think we should check it by '!isalnum()'. (allow-list method)
> >
> > > + *(output_suffix + i) = '_';
> > > + break;
> > > + default:
> > > + }
> > > + i++;
> > > + }
> > > + } else {
> > > + create_suffix(name, output_suffix);
> > > + }
> > > +}
> > > +
> > > +static int filter_symbols(char *symbol, const char **ignore_list, int regex_no)
> > > +{
> > > + regex_t regex;
> > > + int res, i;
> > > +
> > > + for (i = 0; i < regex_no; i++) {
> > > + res = regcomp(®ex, ignore_list[i], REG_EXTENDED);
> > > + if (res)
> > > + return -EREGEX;
> > > +
> > > + res = regexec(®ex, symbol, 0, NULL, 0);
> > > + regfree(®ex);
> > > + switch (res) {
> > > + case 0:
> > > + return FMATCH;
> > > + case REG_NOMATCH:
> > > + break;
> > > + default:
> > > + return -EREGEX;
> > > + }
> > > + }
> > > +
> > > + return FNOMATCH;
> > > +}
> > > +
> > > +int main(int argc, char *argv[])
> > > +{
> > > + char t, sym_name[MAX_NAME_SIZE], new_name[MAX_NAME_SIZE + 15];
> > > + struct duplicate_item *duplicate_iterator;
> > > + struct duplicate_item *duplicate;
> > > + struct item *head = {NULL};
> > > + bool need_2_process = true;
> > > + struct item *last = {NULL};
> > > + struct item *current;
> > > + int verbose_mode = 0;
> > > + uint64_t address;
> > > + FILE *fp;
> > > + int res;
> > > +
> > > + if (argc < 2 || argc > 3) {
> > > + printf("Usage: %s <nmfile> [-verbose]\n", argv[0]);
> > > + return 1;
> > > + }
> > > +
> > > + if (argc == 3 && strcmp(argv[2], "-verbose") == 0)
> > > + verbose_mode = 1;
> > > +
> > > + verbose_msg(verbose_mode, "Scanning nm data(%s)\n", argv[1]);
> > > +
> > > + fp = fopen(argv[1], "r");
> > > + if (!fp) {
> > > + printf("Can't open input file.\n");
> > > + return 1;
> > > + }
> > > +
> > > + if (!addr2line_init(get_addr2line(A2L_DEFAULT), get_vmlinux(argv[1])))
> > > + return 1;
> > > +
> > > + while (fscanf(fp, "%lx %c %99s\n", &address, &t, sym_name) == 3) {
> > > + if (strstr(sym_name, "@_")) {
> > > + if (verbose_mode && need_2_process)
> > > + printf("Already processed\n");
> > > + need_2_process = false;
> > > + }
> > > + last = add_item(&last, sym_name, t, address);
> > > + if (!last) {
> > > + printf("Error in allocate memory\n");
> > > + free_items(&head);
> > > + return 1;
> > > + }
> > > +
> > > + if (!head)
> > > + head = last;
> > > + }
> > > +
> > > + fclose(fp);
> > > +
> > > + if (need_2_process) {
> > > + verbose_msg(verbose_mode, "Sorting nm data\n");
> > > + sort_list_m(&head, BY_NAME);
> > > + verbose_msg(verbose_mode, "Scanning nm data for duplicates\n");
> > > + duplicate = find_duplicates(head);
> > > + if (!duplicate) {
> > > + printf("Error in duplicates list\n");
> > > + return 1;
> > > + }
> > > +
> > > + verbose_msg(verbose_mode, "Applying suffixes\n");
> > > + build_index(head);
> > > + duplicate_iterator = duplicate;
> > > + while (duplicate_iterator) {
> > > + res = filter_symbols(duplicate_iterator->original_item->symb_name,
> > > + ignore_regex, sizeof(ignore_regex) /
> > > + sizeof(ignore_regex[0]));
> > > + if (res != FMATCH &&
> > > + SYMB_NEEDS_ALIAS(duplicate_iterator->original_item)) {
> > > + if (res < 0)
> > > + return 1;
> > > +
> > > + create_file_suffix(duplicate_iterator->original_item->symb_name,
> > > + duplicate_iterator->original_item->addr,
> > > + new_name, vmlinux_path);
> > > + if (!insert_after(head, duplicate_iterator->original_item->addr,
> > > + new_name, duplicate_iterator->original_item->addr,
> > > + duplicate_iterator->original_item->stype))
> > > + return 1;
> > > + }
> > > +
> > > + duplicate_iterator = duplicate_iterator->next;
> > > + }
> > > +
> > > + sort_list_m(&head, BY_ADDRESS);
> > > + }
> > > + current = head;
> > > + while (current) {
> > > + printf("%08lx %c %s\n", current->addr, current->stype, current->symb_name);
> > > + current = current->next;
> > > + }
> > > +
> > > + free_items(&head);
> > > + free_duplicates(&duplicate);
> > > + addr2line_cleanup();
> > > + return 0;
> > > +}
> > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> > > index a432b171be82..cacf60b597ce 100755
> > > --- a/scripts/link-vmlinux.sh
> > > +++ b/scripts/link-vmlinux.sh
> > > @@ -89,8 +89,9 @@ vmlinux_link()
> > >
> > > ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
> > >
> > > - # The kallsyms linking does not need debug symbols included.
> > > - if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> > > + # The kallsyms linking does not need debug symbols included, unless the KALLSYMS_ALIAS.
> > > + if [ ! is_enabled CONFIG_KALLSYMS_ALIAS ] && \
> > > + [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> > > ldflags="${ldflags} ${wl}--strip-debug"
> > > fi
> > >
> > > @@ -161,7 +162,11 @@ kallsyms()
> > > fi
> > >
> > > info KSYMS ${2}
> > > - scripts/kallsyms ${kallsymopt} ${1} > ${2}
> > > + if is_enabled CONFIG_KALLSYMS_ALIAS; then
> > > + ALIAS=".alias"
> > > + scripts/kas_alias/kas_alias ${1} >${1}${ALIAS}
> > > + fi
> >
> > Nit: wrong indentation.
> > And ALIAS is not defined if CONFIG_KALLSYMS_ALIAS=n.
>
> I rely on the fact that ALIAS is undefined if CONFIG_KALLSYMS_ALIAS=n.
> The undefined variable expands to an empty string, and I was constructing
> my name using this approach. This method functions in this manner with
> all the shells I'm familiar with.
yeah, but I feel this is fragile. you can just add "else" block and
initialize ALIAS with empty string for maintenanceability.
> However, I acknowledge that it's more of a hack than a clean programming
> practice. In version 4, I will provide a cleaner shell programming
> solution.
OK.
Thank you!
>
> >
> >
> > > + scripts/kallsyms ${kallsymopt} ${1}${ALIAS} > ${2}
> > > }
> > >
> > > # Perform one step in kallsyms generation, including temporary linking of
> > > --
> > > 2.34.1
> > >
> >
> >
> > Thank you,
> >
> > --
> > Masami Hiramatsu (Google) <[email protected]>
--
Masami Hiramatsu (Google) <[email protected]>
Hello Alexander,
Thank you for your mail.
Il giorno lun 11 set 2023 alle ore 16:26 Alexander Lobakin
<[email protected]> ha scritto:
>
> From: Alessandro Carminati (Red Hat) <[email protected]>
> Date: Mon, 28 Aug 2023 08:04:23 +0000
>
> > From: Alessandro Carminati <[email protected]>
> >
> > It is not uncommon for drivers or modules related to similar peripherals
> > to have symbols with the exact same name.
>
> [...]
>
> > Changes from v2:
> > - Alias tags are created by querying DWARF information from the vmlinux.
> > - The filename + line number is normalized and appended to the original name.
> > - The tag begins with '@' to indicate the symbol source.
> > - Not a change, but worth mentioning, since the alias is added to the existing
> > list, the old duplicated name is preserved, and the livepatch way of dealing
> > with duplicates is maintained.
> > - Acknowledging the existence of scenarios where inlined functions declared in
> > header files may result in multiple copies due to compiler behavior, though
> > it is not actionable as it does not pose an operational issue.
> > - Highlighting a single exception where the same name refers to different
> > functions: the case of "compat_binfmt_elf.c," which directly includes
> > "binfmt_elf.c" producing identical function copies in two separate
> > modules.
>
> Oh, I thought you managed to handle this in v3 since you didn't reply in
> the previous thread...
I want to thank you for this observation because it gives me the chance to
discuss this topic.
It is evident that the corner case in question is inherently challenging
to address using the addr2line approach. Attempting to conceal this
limitation would be counterproductive.
compat_binfmt_elf.c includes directly binfmt_elf.c, addr2line can't help
but report all functions and data declared in that file, coming from that
file. compat_binfmt_elf.c is just a bunch of macro definitions that
rename a few symbols and define some items used in macro-defined
compilation in binfmt_elf.c.
Looking at the functions, only two of the functions defined by
compat_binfmt_elf.c are binary different from their counterpart in
binfmt_elf.c.
These differences, while present, are indeed minimal, but this fact not
relevant to this discussion.
My position is that, rather than producing a more complicated pipeline
to handle this corner case, it is better to fix it. Before reading your
message, I was about to send the v4, but now I'd prefer to hear the
others' opinions on this matter before taking any future action.
>
> >
> > sample from new v3
> >
> > ~ # cat /proc/kallsyms | grep gic_mask_irq
> > ffffd0b03c04dae4 t gic_mask_irq
> > ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> > ffffd0b03c050960 t gic_mask_irq
> > ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
>
> BTW, why normalize them? Why not just
>
> gic_mask_irq@drivers/irqchip/...
>
> Aaaaand why line number? Line numbers break reproducible builds and also
> would make it harder to refer to a particular symbol by its path and
> name since we also have to pass its line number which may change once
> you add a debug print there, for example.
> OTOH there can't be 2 symbols with the same name within one file, so
> just path + name would be enough. Or not?
Regarding the use of full file paths and line numbers for symbol decoration,
it indeed provides the highest level of uniqueness for each symbol.
However, I understand your point that this level of detail might be more than
necessary.
This approach was implemented in response to a specific request expressed in
the live-patching list, and I wanted to ensure we met those requirements.
I am open to revisiting this aspect, and I am willing to accommodate changes
based on feedback.
If you believe that simplifying the format to just path + name would be more
practical, or if you think that eliminating line numbers is a better choice
to avoid potential issues while debugging builds, I'm open to considering
these adjustments.
Additionally, I've interpreted and implemented Francis's suggestion as making
the separator a configurable option, but maybe a proper format string here,
would be more appropriate.
>
> (sorry if some of this was already discussed previously)
>
> [...]
>
> Thanks,
> Olek
Thank you,
Alessandro
On Tue 2023-09-12 16:18:00, Alessandro Carminati wrote:
> <[email protected]> ha scritto:
> > From: Alessandro Carminati (Red Hat) <[email protected]>
> > > sample from new v3
> > >
> > > ~ # cat /proc/kallsyms | grep gic_mask_irq
> > > ffffd0b03c04dae4 t gic_mask_irq
> > > ffffd0b03c04dae4 t gic_mask_irq@_drivers_irqchip_irq-gic_c_167
> > > ffffd0b03c050960 t gic_mask_irq
> > > ffffd0b03c050960 t gic_mask_irq@_drivers_irqchip_irq-gic-v3_c_404
> >
> > BTW, why normalize them? Why not just
> >
> > gic_mask_irq@drivers/irqchip/...
> >
> > Aaaaand why line number? Line numbers break reproducible builds and also
> > would make it harder to refer to a particular symbol by its path and
> > name since we also have to pass its line number which may change once
> > you add a debug print there, for example.
> > OTOH there can't be 2 symbols with the same name within one file, so
> > just path + name would be enough. Or not?
I am afraid that there can be more symbols with the same name in a
single source file. For example, static variables defined inside
functions:
$> cat >test-duplicate-symbols.c <<EOT
#include <stdio.h>
void a(void)
{
static int duplicate_var = 100;
printf("%s: %d\n", __func__, duplicate_var);
}
void b(void)
{
static int duplicate_var = 200;
printf("%s: %d\n", __func__, duplicate_var);
}
int main(int argc, char *argv)
{
a();
b();
}
EOT
$> gcc -o test-duplicate-symbols test-duplicate-symbols.c
$> ./test-duplicate-symbols
a: 100
b: 200
$> objdump -t test-duplicate-symbols | grep duplicate
test-duplicate-symbols: file format elf64-x86-64
0000000000000000 l df *ABS* 0000000000000000 test-duplicate-symbols.c
0000000000402018 l O .data 0000000000000004 duplicate_var.2190
000000000040201c l O .data 0000000000000004 duplicate_var.2195
> Regarding the use of full file paths and line numbers for symbol decoration,
> it indeed provides the highest level of uniqueness for each symbol.
> However, I understand your point that this level of detail might be more than
> necessary.
>
> This approach was implemented in response to a specific request expressed in
> the live-patching list, and I wanted to ensure we met those requirements.
> I am open to revisiting this aspect, and I am willing to accommodate changes
> based on feedback.
Yeah, livepatching needs to be able to find any symbol which might
need to be accessed from the livepatch.
The line number is perfectly fine for livepatching because there
is 1:1:1 relationship between the kernel sources, binary, and
livepatch.
And it might be even useful for the tracing. It helps to find
and investigate the traced code easily.
Hmm, I understand that it complicates the live for the trace
tooling. I wonder if we could allow searching the symbols
with a pattern, e.g. the bash style
"duplicated_symbol_name-source_file_c*"
> If you believe that simplifying the format to just path + name would be more
> practical, or if you think that eliminating line numbers is a better choice
> to avoid potential issues while debugging builds, I'm open to considering
> these adjustments.
> Additionally, I've interpreted and implemented Francis's suggestion as making
> the separator a configurable option, but maybe a proper format string here,
> would be more appropriate.
Please, do not make the format configurable. I think that it will
cause more harm than good. It would make the life more complicated
for developing tracing tools.
The tools would need to support all the formats as well. Or they
would support only some and will not be able to trace kernels
with the others. Both is bad.
Anyway, thanks a lot for working on this.
Best Regards,
Petr