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kasan, arm64: tests supports for HW_TAGS async mode

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This change adds KASAN-KUnit tests support for the async HW_TAGS mode.

In async mode, tag fault aren't being generated synchronously when a
bad access happens, but are instead explicitly checked for by the kernel.

As each KASAN-KUnit test expect a fault to happen before the test is over,
check for faults as a part of the test handler.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210315132019.33202-10-vincenzo.frascino@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Andrey Konovalov 2021-03-15 13:20:19 +00:00 committed by Catalin Marinas
parent eab0e6e17d
commit e80a76aa1a
5 changed files with 29 additions and 6 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
arch/arm64/include/asm/memory.h
View file

@ -246,6 +246,7 @@ static inline const void *__tag_set(const void *addr, u8 tag)
#define arch_enable_tagging_sync() mte_enable_kernel_sync()
#define arch_enable_tagging_async() mte_enable_kernel_async()
#define arch_set_tagging_report_once(state) mte_set_report_once(state)
#define arch_force_async_tag_fault() mte_check_tfsr_exit()
#define arch_init_tags(max_tag) mte_init_tags(max_tag)
#define arch_get_random_tag() mte_get_random_tag()
#define arch_get_mem_tag(addr) mte_get_mem_tag(addr)

17
lib/test_kasan.c
View file

@ -69,10 +69,10 @@ static void kasan_test_exit(struct kunit *test)
* resource named "kasan_data". Do not use this name for KUnit resources
* outside of KASAN tests.
*
* For hardware tag-based KASAN, when a tag fault happens, tag checking is
* normally 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).
* For hardware tag-based KASAN in sync mode, when a 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
* fields, it can reorder or optimize away the accesses to those fields.
@ -80,7 +80,8 @@ static void kasan_test_exit(struct kunit *test)
* expression to prevent that.
*/
#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
!kasan_async_mode_enabled()) \
migrate_disable(); \
WRITE_ONCE(fail_data.report_expected, true); \
WRITE_ONCE(fail_data.report_found, false); \
@ -92,10 +93,14 @@ static void kasan_test_exit(struct kunit *test)
barrier(); \
expression; \
barrier(); \
if (kasan_async_mode_enabled()) \
kasan_force_async_fault(); \
barrier(); \
KUNIT_EXPECT_EQ(test, \
READ_ONCE(fail_data.report_expected), \
READ_ONCE(fail_data.report_found)); \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \
!kasan_async_mode_enabled()) { \
if (READ_ONCE(fail_data.report_found)) \
kasan_enable_tagging_sync(); \
migrate_enable(); \

6
mm/kasan/hw_tags.c
View file

@ -252,4 +252,10 @@ void kasan_enable_tagging_sync(void)
}
EXPORT_SYMBOL_GPL(kasan_enable_tagging_sync);
void kasan_force_async_fault(void)
{
hw_force_async_tag_fault();
}
EXPORT_SYMBOL_GPL(kasan_force_async_fault);
#endif

6
mm/kasan/kasan.h
View file

@ -304,6 +304,9 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
#ifndef arch_set_tagging_report_once
#define arch_set_tagging_report_once(state)
#endif
#ifndef arch_force_async_tag_fault
#define arch_force_async_tag_fault()
#endif
#ifndef arch_get_random_tag
#define arch_get_random_tag() (0xFF)
#endif
@ -318,6 +321,7 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
#define hw_enable_tagging_async() arch_enable_tagging_async()
#define hw_init_tags(max_tag) arch_init_tags(max_tag)
#define hw_set_tagging_report_once(state) arch_set_tagging_report_once(state)
#define hw_force_async_tag_fault() arch_force_async_tag_fault()
#define hw_get_random_tag() arch_get_random_tag()
#define hw_get_mem_tag(addr) arch_get_mem_tag(addr)
#define hw_set_mem_tag_range(addr, size, tag) arch_set_mem_tag_range((addr), (size), (tag))
@ -334,11 +338,13 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
void kasan_set_tagging_report_once(bool state);
void kasan_enable_tagging_sync(void);
void kasan_force_async_fault(void);
#else /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */
static inline void kasan_set_tagging_report_once(bool state) { }
static inline void kasan_enable_tagging_sync(void) { }
static inline void kasan_force_async_fault(void) { }
#endif /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */

5
mm/kasan/report.c
View file

@ -366,6 +366,11 @@ void kasan_report_async(void)
{
unsigned long flags;
#if IS_ENABLED(CONFIG_KUNIT)
if (current->kunit_test)
kasan_update_kunit_status(current->kunit_test);
#endif /* IS_ENABLED(CONFIG_KUNIT) */
start_report(&flags);
pr_err("BUG: KASAN: invalid-access\n");
pr_err("Asynchronous mode enabled: no access details available\n");