kernel/kcsan/debugfs.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 #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"

 /*
  * Statistics counters.
  */
 static atomic_long_t counters[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);

 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]);
 }

 /*
  * 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);
 	cycles_t cycles;

 	/* We may have been called from an atomic region; reset context. */
 	memset(&current->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("KCSAN: %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("KCSAN: %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;
 	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("KCSAN: 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_to_name(i),
 			   atomic_long_read(&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 (!strncmp(arg, "microbench=", sizeof("microbench=") - 1)) {
 		unsigned long iters;

 		if (kstrtoul(&arg[sizeof("microbench=") - 1], 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")) {
 		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
 };

 void __init kcsan_debugfs_init(void)
 {
 	debugfs_create_file("kcsan", 0644, NULL, NULL, &debugfs_ops);
 }
	// SPDX-License-Identifier: GPL-2.0

	#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"

	/*
	* Statistics counters.
	*/
	static atomic_long_t counters[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);

	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]);
	}

	/*
	* 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);
	cycles_t cycles;

	/* We may have been called from an atomic region; reset context. */
	memset(&current->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("KCSAN: %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("KCSAN: %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;
	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("KCSAN: 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_to_name(i),
	atomic_long_read(&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 (!strncmp(arg, "microbench=", sizeof("microbench=") - 1)) {
	unsigned long iters;

	if (kstrtoul(&arg[sizeof("microbench=") - 1], 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")) {
	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
	};

	void __init kcsan_debugfs_init(void)
	{
	debugfs_create_file("kcsan", 0644, NULL, NULL, &debugfs_ops);
	}