UPSTREAM: 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 <[email protected]> Cc: Alexander Potapenko <[email protected]> Cc: Andrey Konovalov <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Will Deacon <[email protected]> Cc: Vincenzo Frascino <[email protected]> Reviewed-by: Catalin Marinas <[email protected]> Reviewed-by: Andrey Konovalov <[email protected]> Tested-by: Andrey Konovalov <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Catalin Marinas <[email protected]> (cherry picked from commit 7672150) Bug: 217222520 Change-Id: Ibfd99f35874670a925a1b53a8e0c42604cdc08f4 Signed-off-by: Andrey Konovalov <[email protected]>
xairy · Feb 8, 2022 · de3ea60 · de3ea60
1 parent 92ec523
commit de3ea60
Show file tree

Hide file tree

Showing 7 changed files with 1 addition and 54 deletions.
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
@@ -234,7 +234,6 @@ static inline const void *__tag_set(const void *addr, u8 tag)
 #ifdef CONFIG_KASAN_HW_TAGS
 #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_get_random_tag()			mte_get_random_tag()
 #define arch_get_mem_tag(addr)			mte_get_mem_tag(addr)

diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
@@ -131,9 +131,6 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag,
 void mte_enable_kernel_sync(void);
 void mte_enable_kernel_async(void);
 
-void mte_set_report_once(bool state);
-bool mte_report_once(void);
-
 #else /* CONFIG_ARM64_MTE */
 
 static inline u8 mte_get_ptr_tag(void *ptr)
@@ -164,15 +161,6 @@ static inline void mte_enable_kernel_async(void)
 {
 }
 
-static inline void mte_set_report_once(bool state)
-{
-}
-
-static inline bool mte_report_once(void)
-{
-	return false;
-}
-
 #endif /* CONFIG_ARM64_MTE */
 
 #endif /* __ASSEMBLY__ */

diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
@@ -23,8 +23,6 @@
 #include <asm/ptrace.h>
 #include <asm/sysreg.h>
 
-static bool report_fault_once = true;
-
 static DEFINE_PER_CPU_READ_MOSTLY(u64, mte_tcf_preferred);
 
 #ifdef CONFIG_KASAN_HW_TAGS
@@ -141,16 +139,6 @@ void mte_enable_kernel_async(void)
 }
 #endif
 
-void mte_set_report_once(bool state)
-{
-	WRITE_ONCE(report_fault_once, state);
-}
-
-bool mte_report_once(void)
-{
-	return READ_ONCE(report_fault_once);
-}
-
 #ifdef CONFIG_KASAN_HW_TAGS
 void mte_check_tfsr_el1(void)
 {

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
@@ -306,24 +306,11 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
 static void report_tag_fault(unsigned long addr, unsigned int esr,
 			     struct pt_regs *regs)
 {
-	static bool reported;
-	bool is_write;
-
-	if (READ_ONCE(reported))
-		return;
-
-	/*
-	 * This is used for KASAN tests and assumes that no MTE faults
-	 * happened before running the tests.
-	 */
-	if (mte_report_once())
-		WRITE_ONCE(reported, true);
-
 	/*
 	 * SAS bits aren't set for all faults reported in EL1, so we can't
 	 * find out access size.
 	 */
-	is_write = !!(esr & ESR_ELx_WNR);
+	bool is_write = !!(esr & ESR_ELx_WNR);
 	kasan_report(addr, 0, is_write, regs->pc);
 }
 #else

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
@@ -53,7 +53,6 @@ static int kasan_test_init(struct kunit *test)
 	}
 
 	multishot = kasan_save_enable_multi_shot();
-	kasan_set_tagging_report_once(false);
 	fail_data.report_found = false;
 	kunit_add_named_resource(test, NULL, NULL, &resource,
 					"kasan_data", &fail_data);
@@ -62,7 +61,6 @@ static int kasan_test_init(struct kunit *test)
 
 static void kasan_test_exit(struct kunit *test)
 {
-	kasan_set_tagging_report_once(true);
 	kasan_restore_multi_shot(multishot);
 	KUNIT_EXPECT_FALSE(test, fail_data.report_found);
 }

diff --git 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
@@ -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) { }