From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753871AbdCOUNt (ORCPT ); Wed, 15 Mar 2017 16:13:49 -0400 Received: from mail.kernel.org ([198.145.29.136]:51048 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753124AbdCOULX (ORCPT ); Wed, 15 Mar 2017 16:11:23 -0400 Message-Id: <20170315195527.703131481@goodmis.org> User-Agent: quilt/0.63-1 Date: Wed, 15 Mar 2017 15:55:27 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Masami Hiramatsu , "H. Peter Anvin" , Andy Lutomirski , Josh Poimboeuf , Linus Torvalds Subject: [RFC][PATCH 0/5] ftrace/x86_32: Ftrace cleanup and add support for -mfentry Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With the issues of gcc screwing around with the mcount stack frame causing function graph tracer to panic on x86_32, and with Linus saying that we should start deprecating mcount (at least on x86), I figured that x86_32 needs to support fentry. First, I renamed mcount_64.S to ftrace_64.S (hmm, my subject says ftrace.S, oh well, this is still RFC, I'll fix that before posting). As we want to get away from mcount, having the ftrace code in a file called mcount seems rather backwards. Next I moved the ftrace code out of entry_32.S. It's not in entry_64.S and it does not belong in entry_32.S. I noticed that the x86_32 code has the same issue as the x86_64 did in the past with respect to a stack frame. I fixed that just for the main ftrace_caller. The ftrace_regs_caller is rather special, and so is function graph tracing. I realized the ftrace_regs_caller code was complex due to me aggressively saving flags, even though I could still do push, lea and mov without changing them. That made the logic a little nicer. Finally I added the fentry code. I tested this (and I'm currently testing it) with an old compiler (for mcount) with and without FRAME_POINTER set. I also did it with a new compiler (with fentry), with and without FRAME_POINTER. I tested function tracing, stack tracing, function_graph tracing, and kprobes (as that uses the ftrace_regs_caller). So far this works. I'm still testing but I'm confident enough with the current code to post an RFC. Thoughts? -- Steve Steven Rostedt (VMware) (5): x86/ftrace: Rename mcount_64.S to ftrace.S ftrace/x86-32: Move the ftrace specific code out of entry_32.S ftrace/x86_32: Add stack frame pointer to ftrace_caller ftrace/x86_32: Clean up ftrace_regs_caller ftrace/x86-32: Add -mfentry support to x86_32 with DYNAMIC_FTRACE set ---- Makefile | 12 +- arch/x86/Kconfig | 2 +- arch/x86/entry/entry_32.S | 168 ----------------- arch/x86/kernel/Makefile | 5 +- arch/x86/kernel/ftrace_32.S | 257 +++++++++++++++++++++++++++ arch/x86/kernel/{mcount_64.S => ftrace_64.S} | 0 6 files changed, 267 insertions(+), 177 deletions(-) create mode 100644 arch/x86/kernel/ftrace_32.S rename arch/x86/kernel/{mcount_64.S => ftrace_64.S} (100%)