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arm64: kasan: mte: remove redundant mte_report_once logic

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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>
This commit is contained in:
Mark Rutland 2021-07-14 15:38:43 +01:00 committed by Catalin Marinas
parent 8286824789
commit 7672150301
7 changed files with 1 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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

@ -243,7 +243,6 @@ 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)

12
arch/arm64/include/asm/mte-kasan.h
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@ -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__ */

12
arch/arm64/kernel/mte.c
View File

@ -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)
{

15
arch/arm64/mm/fault.c
View File

@ -309,24 +309,11 @@ 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

2
lib/test_kasan.c
View File

@ -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);
}

6
mm/kasan/hw_tags.c
View File

@ -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();

7
mm/kasan/kasan.h
View File

@ -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) { }