// SPDX-License-Identifier: GPL-2.0/* * KCSAN short boot-time selftests. * * Copyright (C) 2019, Google LLC. */ #define pr_fmt(fmt) "kcsan: " fmt #include <linux/atomic.h>#include <linux/bitops.h>#include <linux/init.h>#include <linux/kcsan-checks.h>#include <linux/kernel.h>#include <linux/printk.h>#include <linux/random.h>#include <linux/sched.h>#include <linux/spinlock.h>#include <linux/types.h> #include "encoding.h" #define ITERS_PER_TEST 2000 /* * Test watchpoint encode and decode: check that encoding some access's info, * and then subsequent decode preserves the access's info. */static bool __init test_encode_decode(void){	int i; 	for (i = 0; i < ITERS_PER_TEST; ++i) {		size_t size = get_random_u32_inclusive(1, MAX_ENCODABLE_SIZE);		bool is_write = !!get_random_u32_below(2);		unsigned long verif_masked_addr;		long encoded_watchpoint;		bool verif_is_write;		unsigned long addr;		size_t verif_size; 		get_random_bytes(&addr, sizeof(addr));		if (addr < PAGE_SIZE)			addr = PAGE_SIZE; 		if (WARN_ON(!check_encodable(addr, size)))			return false; 		encoded_watchpoint = encode_watchpoint(addr, size, 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 __init 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;} /* * Correct memory barrier instrumentation is critical to avoiding false * positives: simple test to check at boot certain barriers are always properly * instrumented. See kcsan_test for a more complete test. */static DEFINE_SPINLOCK(test_spinlock);static bool __init test_barrier(void){#ifdef CONFIG_KCSAN_WEAK_MEMORY	struct kcsan_scoped_access *reorder_access = &current->kcsan_ctx.reorder_access;#else	struct kcsan_scoped_access *reorder_access = NULL;#endif	bool ret = true;	arch_spinlock_t arch_spinlock = __ARCH_SPIN_LOCK_UNLOCKED;	atomic_t dummy;	long test_var; 	if (!reorder_access || !IS_ENABLED(CONFIG_SMP))		return true; #define __KCSAN_CHECK_BARRIER(access_type, barrier, name)					\	do {											\		reorder_access->type = (access_type) | KCSAN_ACCESS_SCOPED;			\		reorder_access->size = 1;							\		barrier;									\		if (reorder_access->size != 0) {						\			pr_err("improperly instrumented type=(" #access_type "): " name "\n");	\			ret = false;								\		}										\	} while (0)#define KCSAN_CHECK_READ_BARRIER(b)  __KCSAN_CHECK_BARRIER(0, b, #b)#define KCSAN_CHECK_WRITE_BARRIER(b) __KCSAN_CHECK_BARRIER(KCSAN_ACCESS_WRITE, b, #b)#define KCSAN_CHECK_RW_BARRIER(b)    __KCSAN_CHECK_BARRIER(KCSAN_ACCESS_WRITE | KCSAN_ACCESS_COMPOUND, b, #b) 	kcsan_nestable_atomic_begin(); /* No watchpoints in called functions. */ 	KCSAN_CHECK_READ_BARRIER(mb());	KCSAN_CHECK_READ_BARRIER(rmb());	KCSAN_CHECK_READ_BARRIER(smp_mb());	KCSAN_CHECK_READ_BARRIER(smp_rmb());	KCSAN_CHECK_READ_BARRIER(dma_rmb());	KCSAN_CHECK_READ_BARRIER(smp_mb__before_atomic());	KCSAN_CHECK_READ_BARRIER(smp_mb__after_atomic());	KCSAN_CHECK_READ_BARRIER(smp_mb__after_spinlock());	KCSAN_CHECK_READ_BARRIER(smp_store_mb(test_var, 0));	KCSAN_CHECK_READ_BARRIER(smp_store_release(&test_var, 0));	KCSAN_CHECK_READ_BARRIER(xchg(&test_var, 0));	KCSAN_CHECK_READ_BARRIER(xchg_release(&test_var, 0));	KCSAN_CHECK_READ_BARRIER(cmpxchg(&test_var, 0,  0));	KCSAN_CHECK_READ_BARRIER(cmpxchg_release(&test_var, 0,  0));	KCSAN_CHECK_READ_BARRIER(atomic_set_release(&dummy, 0));	KCSAN_CHECK_READ_BARRIER(atomic_add_return(1, &dummy));	KCSAN_CHECK_READ_BARRIER(atomic_add_return_release(1, &dummy));	KCSAN_CHECK_READ_BARRIER(atomic_fetch_add(1, &dummy));	KCSAN_CHECK_READ_BARRIER(atomic_fetch_add_release(1, &dummy));	KCSAN_CHECK_READ_BARRIER(test_and_set_bit(0, &test_var));	KCSAN_CHECK_READ_BARRIER(test_and_clear_bit(0, &test_var));	KCSAN_CHECK_READ_BARRIER(test_and_change_bit(0, &test_var));	KCSAN_CHECK_READ_BARRIER(clear_bit_unlock(0, &test_var));	KCSAN_CHECK_READ_BARRIER(__clear_bit_unlock(0, &test_var));	arch_spin_lock(&arch_spinlock);	KCSAN_CHECK_READ_BARRIER(arch_spin_unlock(&arch_spinlock));	spin_lock(&test_spinlock);	KCSAN_CHECK_READ_BARRIER(spin_unlock(&test_spinlock)); 	KCSAN_CHECK_WRITE_BARRIER(mb());	KCSAN_CHECK_WRITE_BARRIER(wmb());	KCSAN_CHECK_WRITE_BARRIER(smp_mb());	KCSAN_CHECK_WRITE_BARRIER(smp_wmb());	KCSAN_CHECK_WRITE_BARRIER(dma_wmb());	KCSAN_CHECK_WRITE_BARRIER(smp_mb__before_atomic());	KCSAN_CHECK_WRITE_BARRIER(smp_mb__after_atomic());	KCSAN_CHECK_WRITE_BARRIER(smp_mb__after_spinlock());	KCSAN_CHECK_WRITE_BARRIER(smp_store_mb(test_var, 0));	KCSAN_CHECK_WRITE_BARRIER(smp_store_release(&test_var, 0));	KCSAN_CHECK_WRITE_BARRIER(xchg(&test_var, 0));	KCSAN_CHECK_WRITE_BARRIER(xchg_release(&test_var, 0));	KCSAN_CHECK_WRITE_BARRIER(cmpxchg(&test_var, 0,  0));	KCSAN_CHECK_WRITE_BARRIER(cmpxchg_release(&test_var, 0,  0));	KCSAN_CHECK_WRITE_BARRIER(atomic_set_release(&dummy, 0));	KCSAN_CHECK_WRITE_BARRIER(atomic_add_return(1, &dummy));	KCSAN_CHECK_WRITE_BARRIER(atomic_add_return_release(1, &dummy));	KCSAN_CHECK_WRITE_BARRIER(atomic_fetch_add(1, &dummy));	KCSAN_CHECK_WRITE_BARRIER(atomic_fetch_add_release(1, &dummy));	KCSAN_CHECK_WRITE_BARRIER(test_and_set_bit(0, &test_var));	KCSAN_CHECK_WRITE_BARRIER(test_and_clear_bit(0, &test_var));	KCSAN_CHECK_WRITE_BARRIER(test_and_change_bit(0, &test_var));	KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock(0, &test_var));	KCSAN_CHECK_WRITE_BARRIER(__clear_bit_unlock(0, &test_var));	arch_spin_lock(&arch_spinlock);	KCSAN_CHECK_WRITE_BARRIER(arch_spin_unlock(&arch_spinlock));	spin_lock(&test_spinlock);	KCSAN_CHECK_WRITE_BARRIER(spin_unlock(&test_spinlock)); 	KCSAN_CHECK_RW_BARRIER(mb());	KCSAN_CHECK_RW_BARRIER(wmb());	KCSAN_CHECK_RW_BARRIER(rmb());	KCSAN_CHECK_RW_BARRIER(smp_mb());	KCSAN_CHECK_RW_BARRIER(smp_wmb());	KCSAN_CHECK_RW_BARRIER(smp_rmb());	KCSAN_CHECK_RW_BARRIER(dma_wmb());	KCSAN_CHECK_RW_BARRIER(dma_rmb());	KCSAN_CHECK_RW_BARRIER(smp_mb__before_atomic());	KCSAN_CHECK_RW_BARRIER(smp_mb__after_atomic());	KCSAN_CHECK_RW_BARRIER(smp_mb__after_spinlock());	KCSAN_CHECK_RW_BARRIER(smp_store_mb(test_var, 0));	KCSAN_CHECK_RW_BARRIER(smp_store_release(&test_var, 0));	KCSAN_CHECK_RW_BARRIER(xchg(&test_var, 0));	KCSAN_CHECK_RW_BARRIER(xchg_release(&test_var, 0));	KCSAN_CHECK_RW_BARRIER(cmpxchg(&test_var, 0,  0));	KCSAN_CHECK_RW_BARRIER(cmpxchg_release(&test_var, 0,  0));	KCSAN_CHECK_RW_BARRIER(atomic_set_release(&dummy, 0));	KCSAN_CHECK_RW_BARRIER(atomic_add_return(1, &dummy));	KCSAN_CHECK_RW_BARRIER(atomic_add_return_release(1, &dummy));	KCSAN_CHECK_RW_BARRIER(atomic_fetch_add(1, &dummy));	KCSAN_CHECK_RW_BARRIER(atomic_fetch_add_release(1, &dummy));	KCSAN_CHECK_RW_BARRIER(test_and_set_bit(0, &test_var));	KCSAN_CHECK_RW_BARRIER(test_and_clear_bit(0, &test_var));	KCSAN_CHECK_RW_BARRIER(test_and_change_bit(0, &test_var));	KCSAN_CHECK_RW_BARRIER(clear_bit_unlock(0, &test_var));	KCSAN_CHECK_RW_BARRIER(__clear_bit_unlock(0, &test_var));	arch_spin_lock(&arch_spinlock);	KCSAN_CHECK_RW_BARRIER(arch_spin_unlock(&arch_spinlock));	spin_lock(&test_spinlock);	KCSAN_CHECK_RW_BARRIER(spin_unlock(&test_spinlock));	KCSAN_CHECK_RW_BARRIER(xor_unlock_is_negative_byte(1, &test_var));	KCSAN_CHECK_READ_BARRIER(xor_unlock_is_negative_byte(1, &test_var));	KCSAN_CHECK_WRITE_BARRIER(xor_unlock_is_negative_byte(1, &test_var));	kcsan_nestable_atomic_end(); 	return ret;} 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_encode_decode);	RUN_TEST(test_matching_access);	RUN_TEST(test_barrier); 	pr_info("selftest: %d/%d tests passed\n", passed, total);	if (passed != total)		panic("selftests failed");	return 0;}postcore_initcall(kcsan_selftest);