Cleanups, readability, and cosmetic improvements for KCSAN.
Marco Elver (5):
kcsan: Simplify debugfs counter to name mapping
kcsan: Simplify constant string handling
kcsan: Remove debugfs test command
kcsan: Show message if enabled early
kcsan: Use pr_fmt for consistency
kernel/kcsan/core.c | 8 ++-
kernel/kcsan/debugfs.c | 111 ++++++++--------------------------------
kernel/kcsan/report.c | 4 +-
kernel/kcsan/selftest.c | 8 +--
4 files changed, 33 insertions(+), 98 deletions(-)
--
2.28.0.163.g6104cc2f0b6-goog
Simplify counter ID to name mapping by using an array with designated
inits. This way, we can turn a run-time BUG() into a compile-time static
assertion failure if a counter name is missing.
No functional change intended.
Signed-off-by: Marco Elver <[email protected]>
---
kernel/kcsan/debugfs.c | 33 +++++++++++++--------------------
1 file changed, 13 insertions(+), 20 deletions(-)
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 023e49c58d55..3a9566addeff 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -19,6 +19,18 @@
* Statistics counters.
*/
static atomic_long_t counters[KCSAN_COUNTER_COUNT];
+static const char *const counter_names[] = {
+ [KCSAN_COUNTER_USED_WATCHPOINTS] = "used_watchpoints",
+ [KCSAN_COUNTER_SETUP_WATCHPOINTS] = "setup_watchpoints",
+ [KCSAN_COUNTER_DATA_RACES] = "data_races",
+ [KCSAN_COUNTER_ASSERT_FAILURES] = "assert_failures",
+ [KCSAN_COUNTER_NO_CAPACITY] = "no_capacity",
+ [KCSAN_COUNTER_REPORT_RACES] = "report_races",
+ [KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN] = "races_unknown_origin",
+ [KCSAN_COUNTER_UNENCODABLE_ACCESSES] = "unencodable_accesses",
+ [KCSAN_COUNTER_ENCODING_FALSE_POSITIVES] = "encoding_false_positives",
+};
+static_assert(ARRAY_SIZE(counter_names) == KCSAN_COUNTER_COUNT);
/*
* Addresses for filtering functions from reporting. This list can be used as a
@@ -39,24 +51,6 @@ static struct {
};
static DEFINE_SPINLOCK(report_filterlist_lock);
-static const char *counter_to_name(enum kcsan_counter_id id)
-{
- switch (id) {
- case KCSAN_COUNTER_USED_WATCHPOINTS: return "used_watchpoints";
- case KCSAN_COUNTER_SETUP_WATCHPOINTS: return "setup_watchpoints";
- case KCSAN_COUNTER_DATA_RACES: return "data_races";
- case KCSAN_COUNTER_ASSERT_FAILURES: return "assert_failures";
- case KCSAN_COUNTER_NO_CAPACITY: return "no_capacity";
- case KCSAN_COUNTER_REPORT_RACES: return "report_races";
- case KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN: return "races_unknown_origin";
- case KCSAN_COUNTER_UNENCODABLE_ACCESSES: return "unencodable_accesses";
- case KCSAN_COUNTER_ENCODING_FALSE_POSITIVES: return "encoding_false_positives";
- case KCSAN_COUNTER_COUNT:
- BUG();
- }
- return NULL;
-}
-
void kcsan_counter_inc(enum kcsan_counter_id id)
{
atomic_long_inc(&counters[id]);
@@ -271,8 +265,7 @@ static int show_info(struct seq_file *file, void *v)
/* show stats */
seq_printf(file, "enabled: %i\n", READ_ONCE(kcsan_enabled));
for (i = 0; i < KCSAN_COUNTER_COUNT; ++i)
- seq_printf(file, "%s: %ld\n", counter_to_name(i),
- atomic_long_read(&counters[i]));
+ seq_printf(file, "%s: %ld\n", counter_names[i], atomic_long_read(&counters[i]));
/* show filter functions, and filter type */
spin_lock_irqsave(&report_filterlist_lock, flags);
--
2.28.0.163.g6104cc2f0b6-goog
Simplify checking prefixes and length calculation of constant strings.
For the former, the kernel provides str_has_prefix(), and the latter we
should just use strlen("..") because GCC and Clang have optimizations
that optimize these into constants.
No functional change intended.
Signed-off-by: Marco Elver <[email protected]>
---
kernel/kcsan/debugfs.c | 8 ++++----
kernel/kcsan/report.c | 4 ++--
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 3a9566addeff..116bdd8f050c 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -300,16 +300,16 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o
WRITE_ONCE(kcsan_enabled, true);
} else if (!strcmp(arg, "off")) {
WRITE_ONCE(kcsan_enabled, false);
- } else if (!strncmp(arg, "microbench=", sizeof("microbench=") - 1)) {
+ } else if (str_has_prefix(arg, "microbench=")) {
unsigned long iters;
- if (kstrtoul(&arg[sizeof("microbench=") - 1], 0, &iters))
+ if (kstrtoul(&arg[strlen("microbench=")], 0, &iters))
return -EINVAL;
microbenchmark(iters);
- } else if (!strncmp(arg, "test=", sizeof("test=") - 1)) {
+ } else if (str_has_prefix(arg, "test=")) {
unsigned long iters;
- if (kstrtoul(&arg[sizeof("test=") - 1], 0, &iters))
+ if (kstrtoul(&arg[strlen("test=")], 0, &iters))
return -EINVAL;
test_thread(iters);
} else if (!strcmp(arg, "whitelist")) {
diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index d05052c23261..15add93ff12e 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -279,8 +279,8 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
cur = strnstr(buf, "kcsan_", len);
if (cur) {
- cur += sizeof("kcsan_") - 1;
- if (strncmp(cur, "test", sizeof("test") - 1))
+ cur += strlen("kcsan_");
+ if (!str_has_prefix(cur, "test"))
continue; /* KCSAN runtime function. */
/* KCSAN related test. */
}
--
2.28.0.163.g6104cc2f0b6-goog
Remove the debugfs test command, as it is no longer needed now that we
have the KUnit+Torture based kcsan-test module. This is to avoid
confusion around how KCSAN should be tested, as only the kcsan-test
module is maintained.
Signed-off-by: Marco Elver <[email protected]>
---
kernel/kcsan/debugfs.c | 66 ------------------------------------------
1 file changed, 66 deletions(-)
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 116bdd8f050c..de1da1b01aa4 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -98,66 +98,6 @@ static noinline void microbenchmark(unsigned long iters)
current->kcsan_ctx = ctx_save;
}
-/*
- * Simple test to create conflicting accesses. Write 'test=<iters>' to KCSAN's
- * debugfs file from multiple tasks to generate real conflicts and show reports.
- */
-static long test_dummy;
-static long test_flags;
-static long test_scoped;
-static noinline void test_thread(unsigned long iters)
-{
- const long CHANGE_BITS = 0xff00ff00ff00ff00L;
- const struct kcsan_ctx ctx_save = current->kcsan_ctx;
- cycles_t cycles;
-
- /* We may have been called from an atomic region; reset context. */
- memset(¤t->kcsan_ctx, 0, sizeof(current->kcsan_ctx));
-
- pr_info("KCSAN: %s begin | iters: %lu\n", __func__, iters);
- pr_info("test_dummy@%px, test_flags@%px, test_scoped@%px,\n",
- &test_dummy, &test_flags, &test_scoped);
-
- cycles = get_cycles();
- while (iters--) {
- /* These all should generate reports. */
- __kcsan_check_read(&test_dummy, sizeof(test_dummy));
- ASSERT_EXCLUSIVE_WRITER(test_dummy);
- ASSERT_EXCLUSIVE_ACCESS(test_dummy);
-
- ASSERT_EXCLUSIVE_BITS(test_flags, ~CHANGE_BITS); /* no report */
- __kcsan_check_read(&test_flags, sizeof(test_flags)); /* no report */
-
- ASSERT_EXCLUSIVE_BITS(test_flags, CHANGE_BITS); /* report */
- __kcsan_check_read(&test_flags, sizeof(test_flags)); /* no report */
-
- /* not actually instrumented */
- WRITE_ONCE(test_dummy, iters); /* to observe value-change */
- __kcsan_check_write(&test_dummy, sizeof(test_dummy));
-
- test_flags ^= CHANGE_BITS; /* generate value-change */
- __kcsan_check_write(&test_flags, sizeof(test_flags));
-
- BUG_ON(current->kcsan_ctx.scoped_accesses.prev);
- {
- /* Should generate reports anywhere in this block. */
- ASSERT_EXCLUSIVE_WRITER_SCOPED(test_scoped);
- ASSERT_EXCLUSIVE_ACCESS_SCOPED(test_scoped);
- BUG_ON(!current->kcsan_ctx.scoped_accesses.prev);
- /* Unrelated accesses. */
- __kcsan_check_access(&cycles, sizeof(cycles), 0);
- __kcsan_check_access(&cycles, sizeof(cycles), KCSAN_ACCESS_ATOMIC);
- }
- BUG_ON(current->kcsan_ctx.scoped_accesses.prev);
- }
- cycles = get_cycles() - cycles;
-
- pr_info("KCSAN: %s end | cycles: %llu\n", __func__, cycles);
-
- /* restore context */
- current->kcsan_ctx = ctx_save;
-}
-
static int cmp_filterlist_addrs(const void *rhs, const void *lhs)
{
const unsigned long a = *(const unsigned long *)rhs;
@@ -306,12 +246,6 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o
if (kstrtoul(&arg[strlen("microbench=")], 0, &iters))
return -EINVAL;
microbenchmark(iters);
- } else if (str_has_prefix(arg, "test=")) {
- unsigned long iters;
-
- if (kstrtoul(&arg[strlen("test=")], 0, &iters))
- return -EINVAL;
- test_thread(iters);
} else if (!strcmp(arg, "whitelist")) {
set_report_filterlist_whitelist(true);
} else if (!strcmp(arg, "blacklist")) {
--
2.28.0.163.g6104cc2f0b6-goog
Use the same pr_fmt throughout for consistency. [ The only exception is
report.c, where the format must be kept precisely as-is. ]
Signed-off-by: Marco Elver <[email protected]>
---
kernel/kcsan/debugfs.c | 8 +++++---
kernel/kcsan/selftest.c | 8 +++++---
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index de1da1b01aa4..6c4914fa2fad 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) "kcsan: " fmt
+
#include <linux/atomic.h>
#include <linux/bsearch.h>
#include <linux/bug.h>
@@ -80,7 +82,7 @@ static noinline void microbenchmark(unsigned long iters)
*/
WRITE_ONCE(kcsan_enabled, false);
- pr_info("KCSAN: %s begin | iters: %lu\n", __func__, iters);
+ pr_info("%s begin | iters: %lu\n", __func__, iters);
cycles = get_cycles();
while (iters--) {
@@ -91,7 +93,7 @@ static noinline void microbenchmark(unsigned long iters)
}
cycles = get_cycles() - cycles;
- pr_info("KCSAN: %s end | cycles: %llu\n", __func__, cycles);
+ pr_info("%s end | cycles: %llu\n", __func__, cycles);
WRITE_ONCE(kcsan_enabled, was_enabled);
/* restore context */
@@ -154,7 +156,7 @@ static ssize_t insert_report_filterlist(const char *func)
ssize_t ret = 0;
if (!addr) {
- pr_err("KCSAN: could not find function: '%s'\n", func);
+ pr_err("could not find function: '%s'\n", func);
return -ENOENT;
}
diff --git a/kernel/kcsan/selftest.c b/kernel/kcsan/selftest.c
index d26a052d3383..d98bc208d06d 100644
--- a/kernel/kcsan/selftest.c
+++ b/kernel/kcsan/selftest.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) "kcsan: " fmt
+
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/printk.h>
@@ -116,16 +118,16 @@ static int __init kcsan_selftest(void)
if (do_test()) \
++passed; \
else \
- pr_err("KCSAN selftest: " #do_test " failed"); \
+ pr_err("selftest: " #do_test " failed"); \
} while (0)
RUN_TEST(test_requires);
RUN_TEST(test_encode_decode);
RUN_TEST(test_matching_access);
- pr_info("KCSAN selftest: %d/%d tests passed\n", passed, total);
+ pr_info("selftest: %d/%d tests passed\n", passed, total);
if (passed != total)
- panic("KCSAN selftests failed");
+ panic("selftests failed");
return 0;
}
postcore_initcall(kcsan_selftest);
--
2.28.0.163.g6104cc2f0b6-goog
Show a message in the kernel log if KCSAN was enabled early.
Signed-off-by: Marco Elver <[email protected]>
---
kernel/kcsan/core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index e43a55643e00..23d0c4e4cd3a 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -1,5 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+#define pr_fmt(fmt) "kcsan: " fmt
+
#include <linux/atomic.h>
#include <linux/bug.h>
#include <linux/delay.h>
@@ -442,7 +444,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
if (IS_ENABLED(CONFIG_KCSAN_DEBUG)) {
kcsan_disable_current();
- pr_err("KCSAN: watching %s, size: %zu, addr: %px [slot: %d, encoded: %lx]\n",
+ pr_err("watching %s, size: %zu, addr: %px [slot: %d, encoded: %lx]\n",
is_write ? "write" : "read", size, ptr,
watchpoint_slot((unsigned long)ptr),
encode_watchpoint((unsigned long)ptr, size, is_write));
@@ -601,8 +603,10 @@ void __init kcsan_init(void)
* We are in the init task, and no other tasks should be running;
* WRITE_ONCE without memory barrier is sufficient.
*/
- if (kcsan_early_enable)
+ if (kcsan_early_enable) {
+ pr_info("enabled early\n");
WRITE_ONCE(kcsan_enabled, true);
+ }
}
/* === Exported interface =================================================== */
--
2.28.0.163.g6104cc2f0b6-goog
On Fri, Jul 31, 2020 at 10:17:18AM +0200, Marco Elver wrote:
> Cleanups, readability, and cosmetic improvements for KCSAN.
>
> Marco Elver (5):
> kcsan: Simplify debugfs counter to name mapping
> kcsan: Simplify constant string handling
> kcsan: Remove debugfs test command
> kcsan: Show message if enabled early
> kcsan: Use pr_fmt for consistency
Queued and pushed, thank you!
Thanx, Paul
> kernel/kcsan/core.c | 8 ++-
> kernel/kcsan/debugfs.c | 111 ++++++++--------------------------------
> kernel/kcsan/report.c | 4 +-
> kernel/kcsan/selftest.c | 8 +--
> 4 files changed, 33 insertions(+), 98 deletions(-)
>
> --
> 2.28.0.163.g6104cc2f0b6-goog
>