I have been misled by comments in asm-generic/ptrace.h into thinking
that frame_pointer() is universally available across architectures,
which resulted in a wrong design decision.
Add a comment about frame_pointer in a hope that it will help others
to avoid this mistake in the future.
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Signed-off-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>
---
include/asm-generic/ptrace.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/asm-generic/ptrace.h b/include/asm-generic/ptrace.h
index 82e674f6b337..3186c30bd50d 100644
--- a/include/asm-generic/ptrace.h
+++ b/include/asm-generic/ptrace.h
@@ -59,6 +59,10 @@ static inline void user_stack_pointer_set(struct pt_regs *regs,
#define SET_FP(regs, val) (GET_FP(regs) = (val))
#endif
+/*
+ * Unlike instruction_pointer and user_stack_pointer,
+ * frame_pointer is not universally available across architectures.
+ */
static inline unsigned long frame_pointer(struct pt_regs *regs)
{
return GET_FP(regs);
--
ldv
