From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dmitry V. Levin" Subject: [PATCH] asm-generic/ptrace.h: add a comment about frame_pointer Date: Tue, 11 Dec 2018 00:31:50 +0300 Message-ID: <20181210213150.GA18226@altlinux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Oleg Nesterov , Arnd Bergmann Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org 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 Cc: Arnd Bergmann Cc: linux-arch@vger.kernel.org Signed-off-by: Dmitry V. Levin --- 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