// 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);