by Cody P Schafer

[permalink] [raw]

Subject: [tip:perf/core] perf symbols: Convert dso__load_syms to take 2 symsrc's

Commit-ID: 261360b6e90a782f0a63d8f61a67683c376c88cf
Gitweb: http://git.kernel.org/tip/261360b6e90a782f0a63d8f61a67683c376c88cf
Author: Cody P Schafer <[email protected]>
AuthorDate: Fri, 10 Aug 2012 15:23:01 -0700
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Mon, 13 Aug 2012 14:41:33 -0300

perf symbols: Convert dso__load_syms to take 2 symsrc's

To properly handle platforms with an opd section, both a runtime image
(which contains the opd section but possibly lacks symbols) and a symbol
image (which probably lacks an opd section but has symbols).

The next patch ("perf symbol: use both runtime and debug images")
adjusts the callsite in dso__load() to take advantage of being able to
pass both runtime & debug images.

Assumptions made here:

- The opd section, if it exists in the runtime image, has headers in
both the runtime image and the debug/syms image.

- The index of the opd section (again, only if it exists in the runtime
image) is the same in both the runtime and debug/symbols image.

Both of these are true on RHEL, but it is unclear how accurate they are
in general (on platforms with function descriptors in opd sections).

Signed-off-by: Cody P Schafer <[email protected]>
Cc: David Hansen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Matt Hellsley <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sukadev Bhattiprolu <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/symbol-elf.c | 47 +++++++++++++++++++------------------
tools/perf/util/symbol-minimal.c | 1 +
tools/perf/util/symbol.c | 4 +-
tools/perf/util/symbol.h | 5 ++-
4 files changed, 30 insertions(+), 27 deletions(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 492ebec..36e4a45 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -619,7 +619,8 @@ out_close:
return err;
}

-int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *ss,
+int dso__load_sym(struct dso *dso, struct map *map,
+ struct symsrc *syms_ss, struct symsrc *runtime_ss,
symbol_filter_t filter, int kmodule)
{
struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
@@ -630,31 +631,27 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *ss,
int err = -1;
uint32_t idx;
GElf_Ehdr ehdr;
- GElf_Shdr shdr, opdshdr;
+ GElf_Shdr shdr;
Elf_Data *syms, *opddata = NULL;
GElf_Sym sym;
- Elf_Scn *sec, *sec_strndx, *opdsec;
+ Elf_Scn *sec, *sec_strndx;
Elf *elf;
int nr = 0;
- size_t opdidx = 0;

- dso->symtab_type = ss->type;
+ dso->symtab_type = syms_ss->type;

- if (!ss->symtab) {
- ss->symtab = ss->dynsym;
- ss->symshdr = ss->dynshdr;
+ if (!syms_ss->symtab) {
+ syms_ss->symtab = syms_ss->dynsym;
+ syms_ss->symshdr = syms_ss->dynshdr;
}

- elf = ss->elf;
- ehdr = ss->ehdr;
- sec = ss->symtab;
- shdr = ss->symshdr;
+ elf = syms_ss->elf;
+ ehdr = syms_ss->ehdr;
+ sec = syms_ss->symtab;
+ shdr = syms_ss->symshdr;

- opdsec = ss->opdsec;
- opdshdr = ss->opdshdr;
- opdidx = ss->opdidx;
- if (opdsec)
- opddata = elf_rawdata(opdsec, NULL);
+ if (runtime_ss->opdsec)
+ opddata = elf_rawdata(runtime_ss->opdsec, NULL);

syms = elf_getdata(sec, NULL);
if (syms == NULL)
@@ -679,13 +676,14 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *ss,
nr_syms = shdr.sh_size / shdr.sh_entsize;

memset(&sym, 0, sizeof(sym));
- dso->adjust_symbols = ss->adjust_symbols;
+ dso->adjust_symbols = runtime_ss->adjust_symbols;
elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
struct symbol *f;
const char *elf_name = elf_sym__name(&sym, symstrs);
char *demangled = NULL;
int is_label = elf_sym__is_label(&sym);
const char *section_name;
+ bool used_opd = false;

if (kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
strcmp(elf_name, kmap->ref_reloc_sym->name) == 0)
@@ -704,14 +702,16 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *ss,
continue;
}

- if (opdsec && sym.st_shndx == opdidx) {
- u32 offset = sym.st_value - opdshdr.sh_addr;
+ if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
+ u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
u64 *opd = opddata->d_buf + offset;
sym.st_value = DSO__SWAP(dso, u64, *opd);
- sym.st_shndx = elf_addr_to_index(elf, sym.st_value);
+ sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
+ sym.st_value);
+ used_opd = true;
}

- sec = elf_getscn(elf, sym.st_shndx);
+ sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
if (!sec)
goto out_elf_end;

@@ -777,7 +777,8 @@ int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *ss,
goto new_symbol;
}

- if (curr_dso->adjust_symbols && sym.st_value) {
+ if ((used_opd && runtime_ss->adjust_symbols)
+ || (!used_opd && syms_ss->adjust_symbols)) {
pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
"sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
(u64)sym.st_value, (u64)shdr.sh_addr,
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index 11c2c60..7747ea6 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -280,6 +280,7 @@ int dso__synthesize_plt_symbols(struct dso *dso __used,
}

int dso__load_sym(struct dso *dso, struct map *map __used, struct symsrc *ss,
+ struct symsrc *runtime_ss __used,
symbol_filter_t filter __used, int kmodule __used)
{
unsigned char *build_id[BUILD_ID_SIZE];
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 8e7d74f..739e5a3 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1094,7 +1094,7 @@ restart:
continue;
}

- ret = dso__load_sym(dso, map, &ss, filter, 0);
+ ret = dso__load_sym(dso, map, &ss, &ss, filter, 0);

/*
* Some people seem to have debuginfo files _WITHOUT_ debug
@@ -1380,7 +1380,7 @@ int dso__load_vmlinux(struct dso *dso, struct map *map,
if (symsrc__init(&ss, dso, symfs_vmlinux, symtab_type))
return -1;

- err = dso__load_sym(dso, map, &ss, filter, 0);
+ err = dso__load_sym(dso, map, &ss, &ss, filter, 0);
symsrc__destroy(&ss);

if (err > 0) {
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index fa9f6b1..1f3eed2 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -369,8 +369,9 @@ ssize_t dso__data_read_addr(struct dso *dso, struct map *map,
struct machine *machine, u64 addr,
u8 *data, ssize_t size);
int dso__test_data(void);
-int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *ss,
- symbol_filter_t filter, int kmodule);
+int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss,
+ struct symsrc *runtime_ss, symbol_filter_t filter,
+ int kmodule);
int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss,
struct map *map, symbol_filter_t filter);

2012-08-21 16:11:10

by Cody P Schafer

[permalink] [raw]

Subject: [tip:perf/core] perf symbols: Use both runtime and debug images

Commit-ID: 3aafe5ae08f2aed378e06d78b207883879d25cbe
Gitweb: http://git.kernel.org/tip/3aafe5ae08f2aed378e06d78b207883879d25cbe
Author: Cody P Schafer <[email protected]>
AuthorDate: Fri, 10 Aug 2012 15:23:02 -0700
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Mon, 13 Aug 2012 14:46:55 -0300

perf symbols: Use both runtime and debug images

We keep both a 'runtime' elf image as well as a 'debug' elf image around
and generate symbols by looking at both of these.

This eliminates the need for the want_symtab/goto restart mechanism
combined with iterating over and reopening the elf images a second time.

Also give dso__synthsize_plt_symbols() the runtime image (which has
dynsyms) instead of the symbol image (which may only have a symtab and
no dynsyms).

Previously if a debug image was found all runtime images were ignored.

This fixes 2 issues:

- Symbol resolution to failure on PowerPC systems with debug symbols
installed, as the debug images lack a '.opd' section which contains
function descriptors.

- On all archs, plt synthesis failed when a debug image was loaded and
that debug image lacks a dynsym section while a runtime image has a
dynsym section.

Assumptions:

- If a .opd section exists, it is contained in the highest priority
image with a dynsym section.

- This generally implies that the debug image lacks a dynsym section
(ie: it is marked as NO_BITS).

Signed-off-by: Cody P Schafer <[email protected]>
Cc: David Hansen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Matt Hellsley <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sukadev Bhattiprolu <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/symbol-elf.c | 5 ++
tools/perf/util/symbol-minimal.c | 6 +++
tools/perf/util/symbol.c | 77 +++++++++++++++++++++----------------
tools/perf/util/symbol.h | 1 +
4 files changed, 56 insertions(+), 33 deletions(-)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 36e4a45..5b37e13 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -525,6 +525,11 @@ static int dso__swap_init(struct dso *dso, unsigned char eidata)
return 0;
}

+bool symsrc__possibly_runtime(struct symsrc *ss)
+{
+ return ss->dynsym || ss->opdsec;
+}
+
bool symsrc__has_symtab(struct symsrc *ss)
{
return ss->symtab != NULL;
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index 7747ea6..6738ea1 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -260,6 +260,12 @@ out_close:
return -1;
}

+bool symsrc__possibly_runtime(struct symsrc *ss __used)
+{
+ /* Assume all sym sources could be a runtime image. */
+ return true;
+}
+
bool symsrc__has_symtab(struct symsrc *ss __used)
{
return false;
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 739e5a3..2293a4a 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1026,11 +1026,12 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
{
char *name;
int ret = -1;
- struct symsrc ss;
u_int i;
struct machine *machine;
char *root_dir = (char *) "";
- int want_symtab;
+ int ss_pos = 0;
+ struct symsrc ss_[2];
+ struct symsrc *syms_ss = NULL, *runtime_ss = NULL;

dso__set_loaded(dso, map->type);

@@ -1072,12 +1073,12 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
root_dir = machine->root_dir;

/* Iterate over candidate debug images.
- * On the first pass, only load images if they have a full symtab.
- * Failing that, do a second pass where we accept .dynsym also
+ * Keep track of "interesting" ones (those which have a symtab, dynsym,
+ * and/or opd section) for processing.
*/
- want_symtab = 1;
-restart:
for (i = 0; i < DSO_BINARY_TYPE__SYMTAB_CNT; i++) {
+ struct symsrc *ss = &ss_[ss_pos];
+ bool next_slot = false;

enum dso_binary_type symtab_type = binary_type_symtab[i];

@@ -1086,45 +1087,55 @@ restart:
continue;

/* Name is now the name of the next image to try */
- if (symsrc__init(&ss, dso, name, symtab_type) < 0)
+ if (symsrc__init(ss, dso, name, symtab_type) < 0)
continue;

- if (want_symtab && !symsrc__has_symtab(&ss)) {
- symsrc__destroy(&ss);
- continue;
+ if (!syms_ss && symsrc__has_symtab(ss)) {
+ syms_ss = ss;
+ next_slot = true;
}

- ret = dso__load_sym(dso, map, &ss, &ss, filter, 0);
-
- /*
- * Some people seem to have debuginfo files _WITHOUT_ debug
- * info!?!?
- */
- if (!ret) {
- symsrc__destroy(&ss);
- continue;
+ if (!runtime_ss && symsrc__possibly_runtime(ss)) {
+ runtime_ss = ss;
+ next_slot = true;
}

- if (ret > 0) {
- int nr_plt;
+ if (next_slot) {
+ ss_pos++;

- nr_plt = dso__synthesize_plt_symbols(dso, &ss, map, filter);
- if (nr_plt > 0)
- ret += nr_plt;
- symsrc__destroy(&ss);
- break;
+ if (syms_ss && runtime_ss)
+ break;
}
+
}

- /*
- * If we wanted a full symtab but no image had one,
- * relax our requirements and repeat the search.
- */
- if (ret <= 0 && want_symtab) {
- want_symtab = 0;
- goto restart;
+ if (!runtime_ss && !syms_ss)
+ goto out_free;
+
+ if (runtime_ss && !syms_ss) {
+ syms_ss = runtime_ss;
+ }
+
+ /* We'll have to hope for the best */
+ if (!runtime_ss && syms_ss)
+ runtime_ss = syms_ss;
+
+ if (syms_ss)
+ ret = dso__load_sym(dso, map, syms_ss, runtime_ss, filter, 0);
+ else
+ ret = -1;
+
+ if (ret > 0 && runtime_ss->dynsym) {
+ int nr_plt;
+
+ nr_plt = dso__synthesize_plt_symbols(dso, runtime_ss, map, filter);
+ if (nr_plt > 0)
+ ret += nr_plt;
}

+ for (; ss_pos > 0; ss_pos--)
+ symsrc__destroy(&ss_[ss_pos - 1]);
+out_free:
free(name);
if (ret < 0 && strstr(dso->name, " (deleted)") != NULL)
return 0;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 1f3eed2..fc4b1e6 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -253,6 +253,7 @@ void symsrc__destroy(struct symsrc *ss);
int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
enum dso_binary_type type);
bool symsrc__has_symtab(struct symsrc *ss);
+bool symsrc__possibly_runtime(struct symsrc *ss);

#define DSO__SWAP(dso, type, val) \
({ \