From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751791AbdJTGye (ORCPT ); Fri, 20 Oct 2017 02:54:34 -0400 Received: from mail-ve1eur01on0138.outbound.protection.outlook.com ([104.47.1.138]:52800 "EHLO EUR01-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751014AbdJTGyc (ORCPT ); Fri, 20 Oct 2017 02:54:32 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=avagin@virtuozzo.com; Date: Thu, 19 Oct 2017 23:54:15 -0700 From: Andrei Vagin To: Josh Poimboeuf Cc: Ingo Molnar , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, hpa@zytor.com, tglx@linutronix.de Subject: Re: [2/2] x86/unwind: Make CONFIG_UNWINDER_ORC=y the default in kconfig for 64-bit Message-ID: <20171020065414.GA22860@outlook.office365.com> References: <9b1237bbe7244ed9cdf8db2dcb1253e37e1c341e.1507924831.git.jpoimboe@redhat.com> <20171019165103.GA15123@outlook.office365.com> <20171019181655.7yjgxuebkqzzcz4f@treble> <20171019223522.GA4499@outlook.office365.com> <20171020012804.vbqsrajia3ficwzm@treble> MIME-Version: 1.0 Content-Type: text/plain; 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How critical is it? > > > > > > > > Our test job fails if it detects any warning in a kernel log. Maybe we > > > > need to investigate reasons of this warning and try to eliminate it? > > > > > > > > Here are logs: > > > > https://travis-ci.org/avagin/linux/jobs/289676634 > > > > > > I think it means the unwinder found some bad ORC unwinder metadata. Any > > > chance you have access to the kernel binary? I need to know what code > > > corresponds to that ffffffff95f0d94b address. > > > > > > Or if you can reproduce with the following patch, that should help: > > > > > > > > > diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c > > > index 570b70d3f604..95b633f0ce51 100644 > > > --- a/arch/x86/kernel/unwind_orc.c > > > +++ b/arch/x86/kernel/unwind_orc.c > > > @@ -448,7 +448,7 @@ bool unwind_next_frame(struct unwind_state *state) > > > > > > case ORC_TYPE_REGS_IRET: > > > if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) { > > > - orc_warn("can't dereference iret registers at %p for ip %p\n", > > > + orc_warn("can't dereference iret registers at %p for ip %pB\n", > > > (void *)sp, (void *)orig_ip); > > > goto done; > > > } > > > > I applied your patch and rerun tests. > > > > [ 44.947699] WARNING: can't dereference iret registers at ffff880178f5ffe0 for ip int3+0x5b/0x60 > > Thanks, that was enough for me to figure it out. Can you test the below fix? This patch works for me. I run tests a few times and they found nothing suspicious. Tested-by: Andrei Vagin Thank you! > > > and now here is a warning from kasan: > > > > [ 477.775676] ================================================================== > > [ 477.775845] BUG: KASAN: stack-out-of-bounds in deref_stack_reg+0x11d/0x150 > > The KASAN warning is a known issue for which the fix is a little more > complicated. v1 of the patch was here: > > https://lkml.kernel.org/r/cover.1507128293.git.jpoimboe@redhat.com > > > > diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S > index 49167258d587..f6cdb7a1455e 100644 > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -808,7 +808,7 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt > > .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 > ENTRY(\sym) > - UNWIND_HINT_IRET_REGS offset=8 > + UNWIND_HINT_IRET_REGS offset=\has_error_code*8 > > /* Sanity check */ > .if \shift_ist != -1 && \paranoid == 0 >