From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965220AbcLVPCx (ORCPT ); Thu, 22 Dec 2016 10:02:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53500 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934269AbcLVPCw (ORCPT ); Thu, 22 Dec 2016 10:02:52 -0500 From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Andrey Konovalov , Masami Hiramatsu Subject: [PATCH urgent] Revert "x86/unwind: Detect bad stack return address" Date: Thu, 22 Dec 2016 09:02:49 -0600 Message-Id: <02f296848fbf49fb72dfeea706413ecbd9d4caf6.1482418739.git.jpoimboe@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 22 Dec 2016 15:02:51 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This reverts commit b6959a362177 ("x86/unwind: Detect bad stack return address"). Andrey Konovalov reported an unwinder warning: WARNING: unrecognized kernel stack return address ffffffffa0000001 at ffff88006377fa18 in a.out:4467 The unwind was initiated from an interrupt which occurred while running in the generated code for a kprobe. The unwinder printed the warning because it expected regs->ip to point to a valid text address, but instead it pointed to the generated code. Eventually we may want come up with a way to identify generated kprobe code so the unwinder can know that it's a valid return address. Until then, just remove the warning. Reported-by: Andrey Konovalov Signed-off-by: Josh Poimboeuf --- arch/x86/kernel/unwind_frame.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index 20d4b4e..4443e49 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -51,16 +51,7 @@ unsigned long unwind_get_return_address(struct unwind_state *state) addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, *addr_p, addr_p); - if (!__kernel_text_address(addr)) { - printk_deferred_once(KERN_WARNING - "WARNING: unrecognized kernel stack return address %p at %p in %s:%d\n", - (void *)addr, addr_p, state->task->comm, - state->task->pid); - unwind_dump(state, addr_p); - return 0; - } - - return addr; + return __kernel_text_address(addr) ? addr : 0; } EXPORT_SYMBOL_GPL(unwind_get_return_address); -- 2.7.4