kasan: test: support async (again) and asymm modes for HW_TAGS

Async mode support has already been implemented in commit e80a76aa1a91
("kasan, arm64: tests supports for HW_TAGS async mode") but then got
accidentally broken in commit 99734b535d9b ("kasan: detect false-positives
in tests").

Restore the changes removed by the latter patch and adapt them for asymm
mode: add a sync_fault flag to kunit_kasan_expectation that only get set
if the MTE fault was synchronous, and reenable MTE on such faults in
tests.

Also rename kunit_kasan_expectation to kunit_kasan_status and move its
definition to mm/kasan/kasan.h from include/linux/kasan.h, as this
structure is only internally used by KASAN.  Also put the structure
definition under IS_ENABLED(CONFIG_KUNIT).

Link: https://lkml.kernel.org/r/133970562ccacc93ba19d754012c562351d4a8c8.1645033139.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 903b945..fe36215 100644 (file)
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -19,11 +19,6 @@ struct task_struct;
 #include <linux/linkage.h>
 #include <asm/kasan.h>
 
-/* kasan_data struct is used in KUnit tests for KASAN expected failures */
-struct kunit_kasan_expectation {
-       bool report_found;
-};
-
 #endif
 
 typedef unsigned int __bitwise kasan_vmalloc_flags_t;

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 2addd0c..72391f9 100644 (file)
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -37,7 +37,7 @@ void *kasan_ptr_result;
 int kasan_int_result;
 
 static struct kunit_resource resource;
-static struct kunit_kasan_expectation fail_data;
+static struct kunit_kasan_status test_status;
 static bool multishot;
 
 /*
@@ -54,58 +54,63 @@ static int kasan_test_init(struct kunit *test)
        }
 
        multishot = kasan_save_enable_multi_shot();
-       fail_data.report_found = false;
+       test_status.report_found = false;
+       test_status.sync_fault = false;
        kunit_add_named_resource(test, NULL, NULL, &resource,
-                                       "kasan_data", &fail_data);
+                                       "kasan_status", &test_status);
        return 0;
 }
 
 static void kasan_test_exit(struct kunit *test)
 {
        kasan_restore_multi_shot(multishot);
-       KUNIT_EXPECT_FALSE(test, fail_data.report_found);
+       KUNIT_EXPECT_FALSE(test, test_status.report_found);
 }
 
 /**
  * KUNIT_EXPECT_KASAN_FAIL() - check that the executed expression produces a
  * KASAN report; causes a test failure otherwise. This relies on a KUnit
- * resource named "kasan_data". Do not use this name for KUnit resources
+ * resource named "kasan_status". Do not use this name for KUnit resources
  * outside of KASAN tests.
  *
- * For hardware tag-based KASAN in sync mode, when a tag fault happens, tag
+ * For hardware tag-based KASAN, when a synchronous tag fault happens, tag
  * checking is auto-disabled. When this happens, this test handler reenables
  * tag checking. As tag checking can be only disabled or enabled per CPU,
  * this handler disables migration (preemption).
  *
- * Since the compiler doesn't see that the expression can change the fail_data
+ * Since the compiler doesn't see that the expression can change the test_status
  * fields, it can reorder or optimize away the accesses to those fields.
  * Use READ/WRITE_ONCE() for the accesses and compiler barriers around the
  * expression to prevent that.
  *
- * In between KUNIT_EXPECT_KASAN_FAIL checks, fail_data.report_found is kept as
- * false. This allows detecting KASAN reports that happen outside of the checks
- * by asserting !fail_data.report_found at the start of KUNIT_EXPECT_KASAN_FAIL
- * and in kasan_test_exit.
+ * In between KUNIT_EXPECT_KASAN_FAIL checks, test_status.report_found is kept
+ * as false. This allows detecting KASAN reports that happen outside of the
+ * checks by asserting !test_status.report_found at the start of
+ * KUNIT_EXPECT_KASAN_FAIL and in kasan_test_exit.
  */
 #define KUNIT_EXPECT_KASAN_FAIL(test, expression) do {                 \
        if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) &&                         \
            kasan_sync_fault_possible())                                \
                migrate_disable();                                      \
-       KUNIT_EXPECT_FALSE(test, READ_ONCE(fail_data.report_found));    \
+       KUNIT_EXPECT_FALSE(test, READ_ONCE(test_status.report_found));  \
        barrier();                                                      \
        expression;                                                     \
        barrier();                                                      \
-       if (!READ_ONCE(fail_data.report_found)) {                       \
+       if (kasan_async_fault_possible())                               \
+               kasan_force_async_fault();                              \
+       if (!READ_ONCE(test_status.report_found)) {                     \
                KUNIT_FAIL(test, KUNIT_SUBTEST_INDENT "KASAN failure "  \
                                "expected in \"" #expression            \
                                 "\", but none occurred");              \
        }                                                               \
-       if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) {                         \
-               if (READ_ONCE(fail_data.report_found))                  \
-                       kasan_enable_tagging_sync();                    \
+       if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) &&                         \
+           kasan_sync_fault_possible()) {                              \
+               if (READ_ONCE(test_status.report_found) &&              \
+                   READ_ONCE(test_status.sync_fault))                  \
+                       kasan_enable_tagging();                         \
                migrate_enable();                                       \
        }                                                               \
-       WRITE_ONCE(fail_data.report_found, false);                      \
+       WRITE_ONCE(test_status.report_found, false);                    \
 } while (0)
 
 #define KASAN_TEST_NEEDS_CONFIG_ON(test, config) do {                  \

diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index fad1887..07a76c4 100644 (file)
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -172,12 +172,7 @@ void kasan_init_hw_tags_cpu(void)
         * Enable async or asymm modes only when explicitly requested
         * through the command line.
         */
-       if (kasan_arg_mode == KASAN_ARG_MODE_ASYNC)
-               hw_enable_tagging_async();
-       else if (kasan_arg_mode == KASAN_ARG_MODE_ASYMM)
-               hw_enable_tagging_asymm();
-       else
-               hw_enable_tagging_sync();
+       kasan_enable_tagging();
 }
 
 /* kasan_init_hw_tags() is called once on boot CPU. */
@@ -343,11 +338,16 @@ void __kasan_poison_vmalloc(const void *start, unsigned long size)
 
 #if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 
-void kasan_enable_tagging_sync(void)
+void kasan_enable_tagging(void)
 {
-       hw_enable_tagging_sync();
+       if (kasan_arg_mode == KASAN_ARG_MODE_ASYNC)
+               hw_enable_tagging_async();
+       else if (kasan_arg_mode == KASAN_ARG_MODE_ASYMM)
+               hw_enable_tagging_asymm();
+       else
+               hw_enable_tagging_sync();
 }
-EXPORT_SYMBOL_GPL(kasan_enable_tagging_sync);
+EXPORT_SYMBOL_GPL(kasan_enable_tagging);
 
 void kasan_force_async_fault(void)
 {

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 4d67408..d1e111b 100644 (file)
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -7,6 +7,16 @@
 #include <linux/kfence.h>
 #include <linux/stackdepot.h>
 
+#if IS_ENABLED(CONFIG_KUNIT)
+
+/* Used in KUnit-compatible KASAN tests. */
+struct kunit_kasan_status {
+       bool report_found;
+       bool sync_fault;
+};
+
+#endif
+
 #ifdef CONFIG_KASAN_HW_TAGS
 
 #include <linux/static_key.h>
@@ -350,12 +360,12 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 
-void kasan_enable_tagging_sync(void);
+void kasan_enable_tagging(void);
 void kasan_force_async_fault(void);
 
 #else /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
 
-static inline void kasan_enable_tagging_sync(void) { }
+static inline void kasan_enable_tagging(void) { }
 static inline void kasan_force_async_fault(void) { }
 
 #endif /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index f141465..137c2c0 100644 (file)
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -336,20 +336,21 @@ static bool report_enabled(void)
 }
 
 #if IS_ENABLED(CONFIG_KUNIT)
-static void kasan_update_kunit_status(struct kunit *cur_test)
+static void kasan_update_kunit_status(struct kunit *cur_test, bool sync)
 {
        struct kunit_resource *resource;
-       struct kunit_kasan_expectation *kasan_data;
+       struct kunit_kasan_status *status;
 
-       resource = kunit_find_named_resource(cur_test, "kasan_data");
+       resource = kunit_find_named_resource(cur_test, "kasan_status");
 
        if (!resource) {
                kunit_set_failure(cur_test);
                return;
        }
 
-       kasan_data = (struct kunit_kasan_expectation *)resource->data;
-       WRITE_ONCE(kasan_data->report_found, true);
+       status = (struct kunit_kasan_status *)resource->data;
+       WRITE_ONCE(status->report_found, true);
+       WRITE_ONCE(status->sync_fault, sync);
        kunit_put_resource(resource);
 }
 #endif /* IS_ENABLED(CONFIG_KUNIT) */
@@ -363,7 +364,7 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
 
 #if IS_ENABLED(CONFIG_KUNIT)
        if (current->kunit_test)
-               kasan_update_kunit_status(current->kunit_test);
+               kasan_update_kunit_status(current->kunit_test, true);
 #endif /* IS_ENABLED(CONFIG_KUNIT) */
 
        start_report(&flags);
@@ -383,7 +384,7 @@ void kasan_report_async(void)
 
 #if IS_ENABLED(CONFIG_KUNIT)
        if (current->kunit_test)
-               kasan_update_kunit_status(current->kunit_test);
+               kasan_update_kunit_status(current->kunit_test, false);
 #endif /* IS_ENABLED(CONFIG_KUNIT) */
 
        start_report(&flags);
@@ -405,7 +406,7 @@ static void __kasan_report(unsigned long addr, size_t size, bool is_write,
 
 #if IS_ENABLED(CONFIG_KUNIT)
        if (current->kunit_test)
-               kasan_update_kunit_status(current->kunit_test);
+               kasan_update_kunit_status(current->kunit_test, true);
 #endif /* IS_ENABLED(CONFIG_KUNIT) */
 
        disable_trace_on_warning();