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// 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);
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