[linux-block.git] / kernel / kcsan / selftest.c

// SPDX-License-Identifier: GPL-2.0
/*
 * KCSAN short boot-time selftests.
 *
 * Copyright (C) 2019, Google LLC.
 */

#define pr_fmt(fmt) "kcsan: " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/random.h>
#include <linux/types.h>

#include "encoding.h"

#define ITERS_PER_TEST 2000

/* Test requirements. */
static bool test_requires(void)
{
	/* random should be initialized for the below tests */
	return prandom_u32() + prandom_u32() != 0;
}

/*
 * Test watchpoint encode and decode: check that encoding some access's info,
 * and then subsequent decode preserves the access's info.
 */
static bool test_encode_decode(void)
{
	int i;

	for (i = 0; i < ITERS_PER_TEST; ++i) {
		size_t size = prandom_u32_max(MAX_ENCODABLE_SIZE) + 1;
		bool is_write = !!prandom_u32_max(2);
		unsigned long addr;

		prandom_bytes(&addr, sizeof(addr));
		if (addr < PAGE_SIZE)
			addr = PAGE_SIZE;

		if (WARN_ON(!check_encodable(addr, size)))
			return false;

		/* Encode and decode */
		{
			const long encoded_watchpoint =
				encode_watchpoint(addr, size, is_write);
			unsigned long verif_masked_addr;
			size_t verif_size;
			bool verif_is_write;

			/* Check special watchpoints */
			if (WARN_ON(decode_watchpoint(
				    INVALID_WATCHPOINT, &verif_masked_addr,
				    &verif_size, &verif_is_write)))
				return false;
			if (WARN_ON(decode_watchpoint(
				    CONSUMED_WATCHPOINT, &verif_masked_addr,
				    &verif_size, &verif_is_write)))
				return false;

			/* Check decoding watchpoint returns same data */
			if (WARN_ON(!decode_watchpoint(
				    encoded_watchpoint, &verif_masked_addr,
				    &verif_size, &verif_is_write)))
				return false;
			if (WARN_ON(verif_masked_addr !=
				    (addr & WATCHPOINT_ADDR_MASK)))
				goto fail;
			if (WARN_ON(verif_size != size))
				goto fail;
			if (WARN_ON(is_write != verif_is_write))
				goto fail;

			continue;
fail:
			pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n",
			       __func__, is_write ? "write" : "read", size,
			       addr, encoded_watchpoint,
			       verif_is_write ? "write" : "read", verif_size,
			       verif_masked_addr);
			return false;
		}
	}

	return true;
}

/* Test access matching function. */
static bool test_matching_access(void)
{
	if (WARN_ON(!matching_access(10, 1, 10, 1)))
		return false;
	if (WARN_ON(!matching_access(10, 2, 11, 1)))
		return false;
	if (WARN_ON(!matching_access(10, 1, 9, 2)))
		return false;
	if (WARN_ON(matching_access(10, 1, 11, 1)))
		return false;
	if (WARN_ON(matching_access(9, 1, 10, 1)))
		return false;

	/*
	 * An access of size 0 could match another access, as demonstrated here.
	 * Rather than add more comparisons to 'matching_access()', which would
	 * end up in the fast-path for *all* checks, check_access() simply
	 * returns for all accesses of size 0.
	 */
	if (WARN_ON(!matching_access(8, 8, 12, 0)))
		return false;

	return true;
}

static int __init kcsan_selftest(void)
{
	int passed = 0;
	int total = 0;

#define RUN_TEST(do_test)                                                      \
	do {                                                                   \
		++total;                                                       \
		if (do_test())                                                 \
			++passed;                                              \
		else                                                           \
			pr_err("selftest: " #do_test " failed");               \
	} while (0)

	RUN_TEST(test_requires);
	RUN_TEST(test_encode_decode);
	RUN_TEST(test_matching_access);

	pr_info("selftest: %d/%d tests passed\n", passed, total);
	if (passed != total)
		panic("selftests failed");
	return 0;
}
postcore_initcall(kcsan_selftest);
Commit	Line	Data
dfd402a4	1	// SPDX-License-Identifier: GPL-2.0
bd0ccc4a ME	2	/*
	3	* KCSAN short boot-time selftests.
	4	*
	5	* Copyright (C) 2019, Google LLC.
	6	*/
dfd402a4	7
178a1877 ME	8	#define pr_fmt(fmt) "kcsan: " fmt
178a1877 ME	9
dfd402a4 ME	10	#include <linux/init.h>
	11	#include <linux/kernel.h>
	12	#include <linux/printk.h>
	13	#include <linux/random.h>
	14	#include <linux/types.h>
	15
	16	#include "encoding.h"
	17
	18	#define ITERS_PER_TEST 2000
	19
	20	/* Test requirements. */
	21	static bool test_requires(void)
	22	{
	23	/* random should be initialized for the below tests */
	24	return prandom_u32() + prandom_u32() != 0;
	25	}
	26
	27	/*
	28	* Test watchpoint encode and decode: check that encoding some access's info,
	29	* and then subsequent decode preserves the access's info.
	30	*/
	31	static bool test_encode_decode(void)
	32	{
	33	int i;
	34
	35	for (i = 0; i < ITERS_PER_TEST; ++i) {
	36	size_t size = prandom_u32_max(MAX_ENCODABLE_SIZE) + 1;
	37	bool is_write = !!prandom_u32_max(2);
	38	unsigned long addr;
	39
	40	prandom_bytes(&addr, sizeof(addr));
4761612f ME	41	if (addr < PAGE_SIZE)
	42	addr = PAGE_SIZE;
	43
dfd402a4 ME	44	if (WARN_ON(!check_encodable(addr, size)))
	45	return false;
	46
5cbaefe9	47	/* Encode and decode */
dfd402a4 ME	48	{
	49	const long encoded_watchpoint =
	50	encode_watchpoint(addr, size, is_write);
	51	unsigned long verif_masked_addr;
	52	size_t verif_size;
	53	bool verif_is_write;
	54
5cbaefe9	55	/* Check special watchpoints */
dfd402a4 ME	56	if (WARN_ON(decode_watchpoint(
	57	INVALID_WATCHPOINT, &verif_masked_addr,
	58	&verif_size, &verif_is_write)))
	59	return false;
	60	if (WARN_ON(decode_watchpoint(
	61	CONSUMED_WATCHPOINT, &verif_masked_addr,
	62	&verif_size, &verif_is_write)))
	63	return false;
	64
5cbaefe9	65	/* Check decoding watchpoint returns same data */
dfd402a4 ME	66	if (WARN_ON(!decode_watchpoint(
	67	encoded_watchpoint, &verif_masked_addr,
	68	&verif_size, &verif_is_write)))
	69	return false;
	70	if (WARN_ON(verif_masked_addr !=
	71	(addr & WATCHPOINT_ADDR_MASK)))
	72	goto fail;
	73	if (WARN_ON(verif_size != size))
	74	goto fail;
	75	if (WARN_ON(is_write != verif_is_write))
	76	goto fail;
	77
	78	continue;
	79	fail:
	80	pr_err("%s fail: %s %zu bytes @ %lx -> encoded: %lx -> %s %zu bytes @ %lx\n",
	81	__func__, is_write ? "write" : "read", size,
	82	addr, encoded_watchpoint,
	83	verif_is_write ? "write" : "read", verif_size,
	84	verif_masked_addr);
	85	return false;
	86	}
	87	}
	88
	89	return true;
	90	}
	91
	92	/* Test access matching function. */
	93	static bool test_matching_access(void)
	94	{
	95	if (WARN_ON(!matching_access(10, 1, 10, 1)))
	96	return false;
	97	if (WARN_ON(!matching_access(10, 2, 11, 1)))
	98	return false;
	99	if (WARN_ON(!matching_access(10, 1, 9, 2)))
	100	return false;
	101	if (WARN_ON(matching_access(10, 1, 11, 1)))
	102	return false;
	103	if (WARN_ON(matching_access(9, 1, 10, 1)))
	104	return false;
ed95f95c ME	105
	106	/*
	107	* An access of size 0 could match another access, as demonstrated here.
	108	* Rather than add more comparisons to 'matching_access()', which would
	109	* end up in the fast-path for all checks, check_access() simply
	110	* returns for all accesses of size 0.
	111	*/
	112	if (WARN_ON(!matching_access(8, 8, 12, 0)))
	113	return false;
	114
dfd402a4 ME	115	return true;
	116	}
	117
	118	static int __init kcsan_selftest(void)
	119	{
	120	int passed = 0;
	121	int total = 0;
	122
	123	#define RUN_TEST(do_test) \
	124	do { \
	125	++total; \
	126	if (do_test()) \
	127	++passed; \
	128	else \
178a1877	129	pr_err("selftest: " #do_test " failed"); \
dfd402a4 ME	130	} while (0)
	131
	132	RUN_TEST(test_requires);
	133	RUN_TEST(test_encode_decode);
	134	RUN_TEST(test_matching_access);
	135
178a1877	136	pr_info("selftest: %d/%d tests passed\n", passed, total);
dfd402a4	137	if (passed != total)
178a1877	138	panic("selftests failed");
dfd402a4 ME	139	return 0;
	140	}
	141	postcore_initcall(kcsan_selftest);