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Diffstat (limited to 'kernel/kcsan/debugfs.c')
-rw-r--r--kernel/kcsan/debugfs.c221
1 files changed, 72 insertions, 149 deletions
diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c
index 023e49c58d55..2af39ba5b70b 100644
--- a/kernel/kcsan/debugfs.c
+++ b/kernel/kcsan/debugfs.c
@@ -1,4 +1,11 @@
// SPDX-License-Identifier: GPL-2.0
+/*
+ * KCSAN debugfs interface.
+ *
+ * Copyright (C) 2019, Google LLC.
+ */
+
+#define pr_fmt(fmt) "kcsan: " fmt
#include <linux/atomic.h>
#include <linux/bsearch.h>
@@ -15,10 +22,19 @@
#include "kcsan.h"
-/*
- * Statistics counters.
- */
-static atomic_long_t counters[KCSAN_COUNTER_COUNT];
+atomic_long_t kcsan_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
@@ -30,42 +46,8 @@ static struct {
int used; /* number of elements used */
bool sorted; /* if elements are sorted */
bool whitelist; /* if list is a blacklist or whitelist */
-} report_filterlist = {
- .addrs = NULL,
- .size = 8, /* small initial size */
- .used = 0,
- .sorted = false,
- .whitelist = false, /* default is blacklist */
-};
-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]);
-}
-
-void kcsan_counter_dec(enum kcsan_counter_id id)
-{
- atomic_long_dec(&counters[id]);
-}
+} report_filterlist;
+static DEFINE_RAW_SPINLOCK(report_filterlist_lock);
/*
* The microbenchmark allows benchmarking KCSAN core runtime only. To run
@@ -76,7 +58,7 @@ static noinline void microbenchmark(unsigned long iters)
{
const struct kcsan_ctx ctx_save = current->kcsan_ctx;
const bool was_enabled = READ_ONCE(kcsan_enabled);
- cycles_t cycles;
+ u64 cycles;
/* We may have been called from an atomic region; reset context. */
memset(&current->kcsan_ctx, 0, sizeof(current->kcsan_ctx));
@@ -86,7 +68,7 @@ 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--) {
@@ -97,73 +79,13 @@ 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 */
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(&current->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;
@@ -182,7 +104,7 @@ bool kcsan_skip_report_debugfs(unsigned long func_addr)
return false;
func_addr -= offset; /* Get function start */
- spin_lock_irqsave(&report_filterlist_lock, flags);
+ raw_spin_lock_irqsave(&report_filterlist_lock, flags);
if (report_filterlist.used == 0)
goto out;
@@ -199,7 +121,7 @@ bool kcsan_skip_report_debugfs(unsigned long func_addr)
ret = !ret;
out:
- spin_unlock_irqrestore(&report_filterlist_lock, flags);
+ raw_spin_unlock_irqrestore(&report_filterlist_lock, flags);
return ret;
}
@@ -207,9 +129,9 @@ static void set_report_filterlist_whitelist(bool whitelist)
{
unsigned long flags;
- spin_lock_irqsave(&report_filterlist_lock, flags);
+ raw_spin_lock_irqsave(&report_filterlist_lock, flags);
report_filterlist.whitelist = whitelist;
- spin_unlock_irqrestore(&report_filterlist_lock, flags);
+ raw_spin_unlock_irqrestore(&report_filterlist_lock, flags);
}
/* Returns 0 on success, error-code otherwise. */
@@ -217,49 +139,52 @@ static ssize_t insert_report_filterlist(const char *func)
{
unsigned long flags;
unsigned long addr = kallsyms_lookup_name(func);
+ unsigned long *delay_free = NULL;
+ unsigned long *new_addrs = NULL;
+ size_t new_size = 0;
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;
}
- spin_lock_irqsave(&report_filterlist_lock, flags);
+retry_alloc:
+ /*
+ * Check if we need an allocation, and re-validate under the lock. Since
+ * the report_filterlist_lock is a raw, cannot allocate under the lock.
+ */
+ if (data_race(report_filterlist.used == report_filterlist.size)) {
+ new_size = (report_filterlist.size ?: 4) * 2;
+ delay_free = new_addrs = kmalloc_array(new_size, sizeof(unsigned long), GFP_KERNEL);
+ if (!new_addrs)
+ return -ENOMEM;
+ }
- if (report_filterlist.addrs == NULL) {
- /* initial allocation */
- report_filterlist.addrs =
- kmalloc_array(report_filterlist.size,
- sizeof(unsigned long), GFP_ATOMIC);
- if (report_filterlist.addrs == NULL) {
- ret = -ENOMEM;
- goto out;
- }
- } else if (report_filterlist.used == report_filterlist.size) {
- /* resize filterlist */
- size_t new_size = report_filterlist.size * 2;
- unsigned long *new_addrs =
- krealloc(report_filterlist.addrs,
- new_size * sizeof(unsigned long), GFP_ATOMIC);
-
- if (new_addrs == NULL) {
- /* leave filterlist itself untouched */
- ret = -ENOMEM;
- goto out;
+ raw_spin_lock_irqsave(&report_filterlist_lock, flags);
+ if (report_filterlist.used == report_filterlist.size) {
+ /* Check we pre-allocated enough, and retry if not. */
+ if (report_filterlist.used >= new_size) {
+ raw_spin_unlock_irqrestore(&report_filterlist_lock, flags);
+ kfree(new_addrs); /* kfree(NULL) is safe */
+ delay_free = new_addrs = NULL;
+ goto retry_alloc;
}
+ if (report_filterlist.used)
+ memcpy(new_addrs, report_filterlist.addrs, report_filterlist.used * sizeof(unsigned long));
+ delay_free = report_filterlist.addrs; /* free the old list */
+ report_filterlist.addrs = new_addrs; /* switch to the new list */
report_filterlist.size = new_size;
- report_filterlist.addrs = new_addrs;
}
/* Note: deduplicating should be done in userspace. */
- report_filterlist.addrs[report_filterlist.used++] =
- kallsyms_lookup_name(func);
+ report_filterlist.addrs[report_filterlist.used++] = addr;
report_filterlist.sorted = false;
-out:
- spin_unlock_irqrestore(&report_filterlist_lock, flags);
+ raw_spin_unlock_irqrestore(&report_filterlist_lock, flags);
+ kfree(delay_free);
return ret;
}
@@ -270,18 +195,19 @@ 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]));
+ for (i = 0; i < KCSAN_COUNTER_COUNT; ++i) {
+ seq_printf(file, "%s: %ld\n", counter_names[i],
+ atomic_long_read(&kcsan_counters[i]));
+ }
/* show filter functions, and filter type */
- spin_lock_irqsave(&report_filterlist_lock, flags);
+ raw_spin_lock_irqsave(&report_filterlist_lock, flags);
seq_printf(file, "\n%s functions: %s\n",
report_filterlist.whitelist ? "whitelisted" : "blacklisted",
report_filterlist.used == 0 ? "none" : "");
for (i = 0; i < report_filterlist.used; ++i)
seq_printf(file, " %ps\n", (void *)report_filterlist.addrs[i]);
- spin_unlock_irqrestore(&report_filterlist_lock, flags);
+ raw_spin_unlock_irqrestore(&report_filterlist_lock, flags);
return 0;
}
@@ -296,7 +222,7 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o
{
char kbuf[KSYM_NAME_LEN];
char *arg;
- int read_len = count < (sizeof(kbuf) - 1) ? count : (sizeof(kbuf) - 1);
+ const size_t read_len = min(count, sizeof(kbuf) - 1);
if (copy_from_user(kbuf, buf, read_len))
return -EFAULT;
@@ -307,18 +233,12 @@ 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)) {
- unsigned long iters;
-
- if (kstrtoul(&arg[sizeof("test=") - 1], 0, &iters))
- return -EINVAL;
- test_thread(iters);
} else if (!strcmp(arg, "whitelist")) {
set_report_filterlist_whitelist(true);
} else if (!strcmp(arg, "blacklist")) {
@@ -343,7 +263,10 @@ static const struct file_operations debugfs_ops =
.release = single_release
};
-void __init kcsan_debugfs_init(void)
+static int __init kcsan_debugfs_init(void)
{
debugfs_create_file("kcsan", 0644, NULL, NULL, &debugfs_ops);
+ return 0;
}
+
+late_initcall(kcsan_debugfs_init);
generated by cgit (git 2.34.1) at 2025-07-25 19:52:28 +0000