From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754620AbcK1HXN (ORCPT ); Mon, 28 Nov 2016 02:23:13 -0500 Received: from terminus.zytor.com ([198.137.202.10]:33580 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754593AbcK1HWx (ORCPT ); Mon, 28 Nov 2016 02:22:53 -0500 Date: Sun, 27 Nov 2016 23:20:54 -0800 From: tip-bot for Josh Poimboeuf Message-ID: Cc: jpoimboe@redhat.com, linux-kernel@vger.kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com, peterz@infradead.org, tglx@linutronix.de Reply-To: mingo@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, jpoimboe@redhat.com, tglx@linutronix.de, peterz@infradead.org, hpa@zytor.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/unwind: Fix guess-unwinder regression Git-Commit-ID: 55f856e640560494518eaf24fe9d2d2089fba71a X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 55f856e640560494518eaf24fe9d2d2089fba71a Gitweb: http://git.kernel.org/tip/55f856e640560494518eaf24fe9d2d2089fba71a Author: Josh Poimboeuf AuthorDate: Sun, 27 Nov 2016 23:13:07 -0600 Committer: Ingo Molnar CommitDate: Mon, 28 Nov 2016 07:47:54 +0100 x86/unwind: Fix guess-unwinder regression My attempt at fixing some KASAN false positive warnings was rather brain dead, and it broke the guess unwinder. With frame pointers disabled, /proc//stack is broken: # cat /proc/1/stack [] 0xffffffffffffffff Restore the code flow to more closely resemble its previous state, while still using READ_ONCE_NOCHECK() macros to silence KASAN false positives. Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: c2d75e03d630 ("x86/unwind: Prevent KASAN false positive warnings in guess unwinder") Link: http://lkml.kernel.org/r/b824f92c2c22eca5ec95ac56bd2a7c84cf0b9df9.1480309971.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/unwind_guess.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c index b80e8bf..22881dd 100644 --- a/arch/x86/kernel/unwind_guess.c +++ b/arch/x86/kernel/unwind_guess.c @@ -7,11 +7,13 @@ unsigned long unwind_get_return_address(struct unwind_state *state) { - unsigned long addr = READ_ONCE_NOCHECK(*state->sp); + unsigned long addr; if (unwind_done(state)) return 0; + addr = READ_ONCE_NOCHECK(*state->sp); + return ftrace_graph_ret_addr(state->task, &state->graph_idx, addr, state->sp); } @@ -25,11 +27,12 @@ bool unwind_next_frame(struct unwind_state *state) return false; do { - unsigned long addr = READ_ONCE_NOCHECK(*state->sp); + for (state->sp++; state->sp < info->end; state->sp++) { + unsigned long addr = READ_ONCE_NOCHECK(*state->sp); - for (state->sp++; state->sp < info->end; state->sp++) if (__kernel_text_address(addr)) return true; + } state->sp = info->next_sp;