arm64: kasan: mte: remove redundant mte_report_once logic

We have special logic to suppress MTE tag check fault reporting, based
on a global `mte_report_once` and `reported` variables. These can be
used to suppress calling kasan_report() when taking a tag check fault,
but do not prevent taking the fault in the first place, nor does they
affect the way we disable tag checks upon taking a fault.

The core KASAN code already defaults to reporting a single fault, and
has a `multi_shot` control to permit reporting multiple faults. The only
place we transiently alter `mte_report_once` is in lib/test_kasan.c,
where we also the `multi_shot` state as the same time. Thus
`mte_report_once` and `reported` are redundant, and can be removed.

When a tag check fault is taken, tag checking will be disabled by
`do_tag_recovery` and must be explicitly re-enabled if desired. The test
code does this by calling kasan_enable_tagging_sync().

This patch removes the redundant mte_report_once() logic and associated
variables.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20210714143843.56537-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2 files changed, 0 insertions, 13 deletions

diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 2c6c6c6ddfa2..e4c16f6b6680 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -248,12 +248,6 @@ void kasan_free_pages(struct page *page, unsigned int order)
 
 #if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 
-void kasan_set_tagging_report_once(bool state)
-{
-	hw_set_tagging_report_once(state);
-}
-EXPORT_SYMBOL_GPL(kasan_set_tagging_report_once);
-
 void kasan_enable_tagging_sync(void)
 {
 	hw_enable_tagging_sync();
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 28a16b80bbef..fff93b0bcb08 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -290,9 +290,6 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 #ifndef arch_enable_tagging_async
 #define arch_enable_tagging_async()
 #endif
-#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
@@ -308,7 +305,6 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #define hw_enable_tagging_sync()		arch_enable_tagging_sync()
 #define hw_enable_tagging_async()		arch_enable_tagging_async()
-#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)
@@ -319,19 +315,16 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 
 #define hw_enable_tagging_sync()
 #define hw_enable_tagging_async()
-#define hw_set_tagging_report_once(state)
 
 #endif /* CONFIG_KASAN_HW_TAGS */
 
 #if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 
-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) { }