276 lines
7.5 KiB
C
276 lines
7.5 KiB
C
// 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>
|
|
#include <linux/bug.h>
|
|
#include <linux/debugfs.h>
|
|
#include <linux/init.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/sort.h>
|
|
#include <linux/string.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
#include "kcsan.h"
|
|
|
|
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
|
|
* whitelist or blacklist.
|
|
*/
|
|
static struct {
|
|
unsigned long *addrs; /* array of addresses */
|
|
size_t size; /* current size */
|
|
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);
|
|
|
|
/*
|
|
* The microbenchmark allows benchmarking KCSAN core runtime only. To run
|
|
* multiple threads, pipe 'microbench=<iters>' from multiple tasks into the
|
|
* debugfs file. This will not generate any conflicts, and tests fast-path only.
|
|
*/
|
|
static noinline void microbenchmark(unsigned long iters)
|
|
{
|
|
const struct kcsan_ctx ctx_save = current->kcsan_ctx;
|
|
const bool was_enabled = READ_ONCE(kcsan_enabled);
|
|
u64 cycles;
|
|
|
|
/* We may have been called from an atomic region; reset context. */
|
|
memset(¤t->kcsan_ctx, 0, sizeof(current->kcsan_ctx));
|
|
/*
|
|
* Disable to benchmark fast-path for all accesses, and (expected
|
|
* negligible) call into slow-path, but never set up watchpoints.
|
|
*/
|
|
WRITE_ONCE(kcsan_enabled, false);
|
|
|
|
pr_info("%s begin | iters: %lu\n", __func__, iters);
|
|
|
|
cycles = get_cycles();
|
|
while (iters--) {
|
|
unsigned long addr = iters & ((PAGE_SIZE << 8) - 1);
|
|
int type = !(iters & 0x7f) ? KCSAN_ACCESS_ATOMIC :
|
|
(!(iters & 0xf) ? KCSAN_ACCESS_WRITE : 0);
|
|
__kcsan_check_access((void *)addr, sizeof(long), type);
|
|
}
|
|
cycles = get_cycles() - cycles;
|
|
|
|
pr_info("%s end | cycles: %llu\n", __func__, cycles);
|
|
|
|
WRITE_ONCE(kcsan_enabled, was_enabled);
|
|
/* 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;
|
|
const unsigned long b = *(const unsigned long *)lhs;
|
|
|
|
return a < b ? -1 : a == b ? 0 : 1;
|
|
}
|
|
|
|
bool kcsan_skip_report_debugfs(unsigned long func_addr)
|
|
{
|
|
unsigned long symbolsize, offset;
|
|
unsigned long flags;
|
|
bool ret = false;
|
|
|
|
if (!kallsyms_lookup_size_offset(func_addr, &symbolsize, &offset))
|
|
return false;
|
|
func_addr -= offset; /* Get function start */
|
|
|
|
spin_lock_irqsave(&report_filterlist_lock, flags);
|
|
if (report_filterlist.used == 0)
|
|
goto out;
|
|
|
|
/* Sort array if it is unsorted, and then do a binary search. */
|
|
if (!report_filterlist.sorted) {
|
|
sort(report_filterlist.addrs, report_filterlist.used,
|
|
sizeof(unsigned long), cmp_filterlist_addrs, NULL);
|
|
report_filterlist.sorted = true;
|
|
}
|
|
ret = !!bsearch(&func_addr, report_filterlist.addrs,
|
|
report_filterlist.used, sizeof(unsigned long),
|
|
cmp_filterlist_addrs);
|
|
if (report_filterlist.whitelist)
|
|
ret = !ret;
|
|
|
|
out:
|
|
spin_unlock_irqrestore(&report_filterlist_lock, flags);
|
|
return ret;
|
|
}
|
|
|
|
static void set_report_filterlist_whitelist(bool whitelist)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&report_filterlist_lock, flags);
|
|
report_filterlist.whitelist = whitelist;
|
|
spin_unlock_irqrestore(&report_filterlist_lock, flags);
|
|
}
|
|
|
|
/* Returns 0 on success, error-code otherwise. */
|
|
static ssize_t insert_report_filterlist(const char *func)
|
|
{
|
|
unsigned long flags;
|
|
unsigned long addr = kallsyms_lookup_name(func);
|
|
ssize_t ret = 0;
|
|
|
|
if (!addr) {
|
|
pr_err("could not find function: '%s'\n", func);
|
|
return -ENOENT;
|
|
}
|
|
|
|
spin_lock_irqsave(&report_filterlist_lock, flags);
|
|
|
|
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;
|
|
}
|
|
|
|
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.sorted = false;
|
|
|
|
out:
|
|
spin_unlock_irqrestore(&report_filterlist_lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int show_info(struct seq_file *file, void *v)
|
|
{
|
|
int i;
|
|
unsigned long flags;
|
|
|
|
/* 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_names[i],
|
|
atomic_long_read(&kcsan_counters[i]));
|
|
}
|
|
|
|
/* show filter functions, and filter type */
|
|
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);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int debugfs_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, show_info, NULL);
|
|
}
|
|
|
|
static ssize_t
|
|
debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *off)
|
|
{
|
|
char kbuf[KSYM_NAME_LEN];
|
|
char *arg;
|
|
int read_len = count < (sizeof(kbuf) - 1) ? count : (sizeof(kbuf) - 1);
|
|
|
|
if (copy_from_user(kbuf, buf, read_len))
|
|
return -EFAULT;
|
|
kbuf[read_len] = '\0';
|
|
arg = strstrip(kbuf);
|
|
|
|
if (!strcmp(arg, "on")) {
|
|
WRITE_ONCE(kcsan_enabled, true);
|
|
} else if (!strcmp(arg, "off")) {
|
|
WRITE_ONCE(kcsan_enabled, false);
|
|
} else if (str_has_prefix(arg, "microbench=")) {
|
|
unsigned long iters;
|
|
|
|
if (kstrtoul(&arg[strlen("microbench=")], 0, &iters))
|
|
return -EINVAL;
|
|
microbenchmark(iters);
|
|
} else if (!strcmp(arg, "whitelist")) {
|
|
set_report_filterlist_whitelist(true);
|
|
} else if (!strcmp(arg, "blacklist")) {
|
|
set_report_filterlist_whitelist(false);
|
|
} else if (arg[0] == '!') {
|
|
ssize_t ret = insert_report_filterlist(&arg[1]);
|
|
|
|
if (ret < 0)
|
|
return ret;
|
|
} else {
|
|
return -EINVAL;
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
static const struct file_operations debugfs_ops =
|
|
{
|
|
.read = seq_read,
|
|
.open = debugfs_open,
|
|
.write = debugfs_write,
|
|
.release = single_release
|
|
};
|
|
|
|
static int __init kcsan_debugfs_init(void)
|
|
{
|
|
debugfs_create_file("kcsan", 0644, NULL, NULL, &debugfs_ops);
|
|
return 0;
|
|
}
|
|
|
|
late_initcall(kcsan_debugfs_init);
|