Historically the fast-path static key `kasan_flag_enabled` existed only for `CONFIG_KASAN_HW_TAGS`. Generic and SW_TAGS either relied on `kasan_arch_is_ready()` or evaluated KASAN checks unconditionally. As a result every architecture had to toggle a private flag in its `kasan_init()`.
This patch turns the flag into a single global runtime predicate that is built for every `CONFIG_KASAN` mode and adds a helper that flips the key once KASAN is ready. Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218315 Signed-off-by: Sabyrzhan Tasbolatov <snovit...@gmail.com> --- include/linux/kasan-enabled.h | 22 ++++++++++++++++------ include/linux/kasan.h | 6 ++++++ mm/kasan/common.c | 7 +++++++ mm/kasan/generic.c | 11 +++++++++++ mm/kasan/hw_tags.c | 7 ------- mm/kasan/sw_tags.c | 2 ++ 6 files changed, 42 insertions(+), 13 deletions(-) diff --git a/include/linux/kasan-enabled.h b/include/linux/kasan-enabled.h index 6f612d69ea0c..2436eb45cfee 100644 --- a/include/linux/kasan-enabled.h +++ b/include/linux/kasan-enabled.h @@ -4,8 +4,12 @@ #include <linux/static_key.h> -#ifdef CONFIG_KASAN_HW_TAGS +#ifdef CONFIG_KASAN +/* + * Global runtime flag. Starts ‘false’; switched to ‘true’ by + * the appropriate kasan_init_*() once KASAN is fully initialized. + */ DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled); static __always_inline bool kasan_enabled(void) @@ -13,18 +17,24 @@ static __always_inline bool kasan_enabled(void) return static_branch_likely(&kasan_flag_enabled); } -static inline bool kasan_hw_tags_enabled(void) +#else /* !CONFIG_KASAN */ + +static __always_inline bool kasan_enabled(void) { - return kasan_enabled(); + return false; } -#else /* CONFIG_KASAN_HW_TAGS */ +#endif /* CONFIG_KASAN */ -static inline bool kasan_enabled(void) +#ifdef CONFIG_KASAN_HW_TAGS + +static inline bool kasan_hw_tags_enabled(void) { - return IS_ENABLED(CONFIG_KASAN); + return kasan_enabled(); } +#else /* !CONFIG_KASAN_HW_TAGS */ + static inline bool kasan_hw_tags_enabled(void) { return false; diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 890011071f2b..51a8293d1af6 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -543,6 +543,12 @@ void kasan_report_async(void); #endif /* CONFIG_KASAN_HW_TAGS */ +#ifdef CONFIG_KASAN_GENERIC +void __init kasan_init_generic(void); +#else +static inline void kasan_init_generic(void) { } +#endif + #ifdef CONFIG_KASAN_SW_TAGS void __init kasan_init_sw_tags(void); #else diff --git a/mm/kasan/common.c b/mm/kasan/common.c index ed4873e18c75..525194da25fa 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -32,6 +32,13 @@ #include "kasan.h" #include "../slab.h" +/* + * Definition of the unified static key declared in kasan-enabled.h. + * This provides consistent runtime enable/disable across all KASAN modes. + */ +DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled); +EXPORT_SYMBOL(kasan_flag_enabled); + struct slab *kasan_addr_to_slab(const void *addr) { if (virt_addr_valid(addr)) diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index d54e89f8c3e7..32c432df24aa 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -36,6 +36,17 @@ #include "kasan.h" #include "../slab.h" +/* + * Initialize Generic KASAN and enable runtime checks. + * This should be called from arch kasan_init() once shadow memory is ready. + */ +void __init kasan_init_generic(void) +{ + static_branch_enable(&kasan_flag_enabled); + + pr_info("KernelAddressSanitizer initialized (generic)\n"); +} + /* * All functions below always inlined so compiler could * perform better optimizations in each of __asan_loadX/__assn_storeX diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 9a6927394b54..8e819fc4a260 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -45,13 +45,6 @@ static enum kasan_arg kasan_arg __ro_after_init; static enum kasan_arg_mode kasan_arg_mode __ro_after_init; static enum kasan_arg_vmalloc kasan_arg_vmalloc __initdata; -/* - * Whether KASAN is enabled at all. - * The value remains false until KASAN is initialized by kasan_init_hw_tags(). - */ -DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled); -EXPORT_SYMBOL(kasan_flag_enabled); - /* * Whether the selected mode is synchronous, asynchronous, or asymmetric. * Defaults to KASAN_MODE_SYNC. diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c index b9382b5b6a37..525bc91e2fcd 100644 --- a/mm/kasan/sw_tags.c +++ b/mm/kasan/sw_tags.c @@ -45,6 +45,8 @@ void __init kasan_init_sw_tags(void) kasan_init_tags(); + static_branch_enable(&kasan_flag_enabled); + pr_info("KernelAddressSanitizer initialized (sw-tags, stacktrace=%s)\n", str_on_off(kasan_stack_collection_enabled())); } -- 2.34.1
