[PATCH bpf-next v3 09/17] mm: kasan: Declare kasan_unpoison_task_stack_below in kasan.h

Kumar Kartikeya Dwivedi
2023-09-12T23:32:25Z

We require access to this kasan helper in BPF code in the next patch
where we have to unpoison the task stack when we unwind and reset the
stack frame from bpf_throw, and it never really unpoisons the poisoned
stack slots on entry when compiler instrumentation is generated by
CONFIG_KASAN_STACK and inline instrumentation is supported.

Also, remove the declaration from mm/kasan/kasan.h as we put it in the
header file kasan.h.

Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
include/linux/kasan.h | 2 ++
mm/kasan/kasan.h | 1 -
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 819b6bc8ac08..7a463f814db2 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -283,8 +283,10 @@ static inline bool kasan_check_byte(const void *address)

#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
void kasan_unpoison_task_stack(struct task_struct *task);
+asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
#else
static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
+static inline void kasan_unpoison_task_stack_below(const void *watermark) {}
#endif

#ifdef CONFIG_KASAN_GENERIC
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 2e973b36fe07..5eefe202bb8f 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -558,7 +558,6 @@ void kasan_restore_multi_shot(bool enabled);
* code. Declared here to avoid warnings about missing declarations.
*/

-asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
void __asan_register_globals(void *globals, ssize_t size);
void __asan_unregister_globals(void *globals, ssize_t size);
void __asan_handle_no_return(void);
--
2.41.0