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-rw-r--r--kernel/kcsan/selftest.c264
1 files changed, 264 insertions, 0 deletions
diff --git a/kernel/kcsan/selftest.c b/kernel/kcsan/selftest.c
new file mode 100644
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+++ b/kernel/kcsan/selftest.c
@@ -0,0 +1,264 @@
+// 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));
+
+#ifdef clear_bit_unlock_is_negative_byte
+ KCSAN_CHECK_RW_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
+ KCSAN_CHECK_READ_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
+ KCSAN_CHECK_WRITE_BARRIER(clear_bit_unlock_is_negative_byte(0, &test_var));
+#endif
+ 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);
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