From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 43C2DE8B387 for ; Wed, 4 Feb 2026 00:45:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A050F6B0088; Tue, 3 Feb 2026 19:45:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9B2D56B0089; Tue, 3 Feb 2026 19:45:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86A456B0092; Tue, 3 Feb 2026 19:45:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 6B1A86B0088 for ; Tue, 3 Feb 2026 19:45:06 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 14CDE1B23E6 for ; Wed, 4 Feb 2026 00:45:06 +0000 (UTC) X-FDA: 84404929812.12.D31791C Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) by imf19.hostedemail.com (Postfix) with ESMTP id DB4471A0008 for ; Wed, 4 Feb 2026 00:45:03 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=fail ("headers rsa verify failed") header.d=zytor.com header.s=2026012301 header.b=A667aHHn; spf=pass (imf19.hostedemail.com: domain of hpa@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=hpa@zytor.com; dmarc=pass (policy=none) header.from=zytor.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770165904; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=SfjcLG/RUmRtt9wxHxBQ6mL+sKk+V7CX7MeisYlYpJc=; b=0BobNyGcLX+URtlgCnRnrEVRxGFMG5pr1vKJDFu2/uFaONhu9Pv1BlVZ8wcZqpvCyin3sb On44Ss+kfaG8CNo46ACxNrFhFrZ8kWCVWXNs9+NRTxzsPTKkv2d/nYaCba/3sZhTamikld iVq0kIWIBFPI3xphgJhnAWbY0md+9I4= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=fail ("headers rsa verify failed") header.d=zytor.com header.s=2026012301 header.b=A667aHHn; spf=pass (imf19.hostedemail.com: domain of hpa@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=hpa@zytor.com; dmarc=pass (policy=none) header.from=zytor.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770165904; a=rsa-sha256; cv=none; b=m3Al/IUxF7pvRG1QqUdhu2GEr5fNKxfUYPN51ptqEgeP5wFbSkflUCgllXPHCwa3hJOld6 DmhRtW3+1WHClqoHQLY42qTNMg7tnEfbBLVA4uppfiCQooMOBYHRDAHJd+Mx6wYCdQAAEm 05hm1vDKc7OfSiuuIOeRFHUTao9bbTE= Received: from [IPV6:2601:646:8081:9484:7f27:8faf:e50:c87b] ([IPv6:2601:646:8081:9484:7f27:8faf:e50:c87b]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 6140hAvH3684475 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Tue, 3 Feb 2026 16:44:10 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 6140hAvH3684475 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026012301; t=1770165853; bh=SfjcLG/RUmRtt9wxHxBQ6mL+sKk+V7CX7MeisYlYpJc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=A667aHHnZjPtA3vHvH0jpqhwqdKf4X6/35CpgUlJSQSe8LQuTsAR5kPmP4uY2ByIn ifXxRqU5OoZ1IoPKwL2BVP5QUwz+R3SGHYL3uh11dVN2rYTroBzK1nnGRvaco9x3AV PJkukzXaZTKyfW4NdDv8FFAy72MvB3KMvFwpcfVVbCZ4l72ccV320HTpY/RDFTQiHJ 0B5tAvHF0AYi85FhQDMbDhUuXXulb3MZHpeluT4WdNX/UDpsLb9qVSVz8Tvxd3EigZ 2CCyraJ5yWcTjnGmIAjRCwmsIoillqKATqXgWxaHjK8wsBFZ/B/ylwPhstUWBamK/p FX9idc7SfXpvw== Message-ID: Date: Tue, 3 Feb 2026 16:43:44 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/6] x86/asm: Avoid emitting DWARF CFI for non-VDSO To: Jens Remus , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, Steven Rostedt Cc: Josh Poimboeuf , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Linus Torvalds , Andrew Morton , Florian Weimer , Kees Cook , "Carlos O'Donell" , Sam James , Dylan Hatch , Borislav Petkov , Dave Hansen , David Hildenbrand , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Heiko Carstens , Vasily Gorbik , "Steven Rostedt (Google)" References: <20260203171958.1522030-1-jremus@linux.ibm.com> <20260203171958.1522030-3-jremus@linux.ibm.com> Content-Language: en-US, sv-SE From: "H. Peter Anvin" In-Reply-To: <20260203171958.1522030-3-jremus@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Stat-Signature: qam7ciw6xgrg81nqyc8jt7dddhyzjfjw X-Rspam-User: X-Rspamd-Queue-Id: DB4471A0008 X-HE-Tag: 1770165903-281249 X-HE-Meta: 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 Ofo1Scjv D55kB6ComiZ1nKT6evRCXhTbRhePYcPDcEKeGyBo9Mctns5+PCs4kVSq+kbO3ovg6o4aC5mEC2gJoZM9/4ZaH6/GZ9wywE7g1rnnxStaOMZzHtRoag/TPd5ltQD6zoTrxQrXi859JScGyddeUrqtj5hdvEUg8R6QeBDhaGwic2xVdtVvpj66+elYX6sSM2LhV0wR9e2ylc3xLpQNcu9fvn6He7tzfPydCFPTDQ2x8ZpA/aoTFhSl0KZQo+8DEgzoM1H1zp2FTtO9bW0RJeAqUFPe7r99gvXhhS6/PX7OyhaEJ3+U8/yifdyAzxSXwl/QJlW5m+nmkiKIaio3izKgNc10UJeaGEnFnqWixK3KBz/JD5B63v/G1qJI71ajVACqDfqgU5mePdWg29AZ0g1ohMPrHGdc8aT/Isj4f7zQK0VEVbg8YqSV6ROkgLcl3ylD/sVgb/Wb6Oy4prj1MCWZ8rk9HwCmIZsNELM7QaGnKbFB5iNg58hclTxeW0QsorzcZCag8YCQ4rB3nS10Ezyk6yCFkBw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-02-03 09:19, Jens Remus wrote: > From: Josh Poimboeuf > > It was decided years ago that .cfi_* annotations aren't maintainable in > the kernel. They were replaced by objtool unwind hints. For the kernel > proper, ensure the CFI_* macros don't do anything. > > On the other hand the VDSO library *does* use them, so user space can > unwind through it. > > Make sure these macros only work for VDSO. They aren't actually being > used outside of VDSO anyway, so there's no functional change. > > Signed-off-by: Josh Poimboeuf > Signed-off-by: Steven Rostedt (Google) > Signed-off-by: Jens Remus > --- > arch/x86/include/asm/dwarf2.h | 51 ++++++++++++++++++++++++----------- > 1 file changed, 35 insertions(+), 16 deletions(-) > > diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h > index 09c9684d3ad6..7cc30500c095 100644 > --- a/arch/x86/include/asm/dwarf2.h > +++ b/arch/x86/include/asm/dwarf2.h > @@ -6,6 +6,15 @@ > #warning "asm/dwarf2.h should be only included in pure assembly files" > #endif > > +#ifdef BUILD_VDSO > + > + /* > + * For the vDSO, emit both runtime unwind information and debug > + * symbols for the .dbg file. > + */ > + > + .cfi_sections .eh_frame, .debug_frame > + > #define CFI_STARTPROC .cfi_startproc > #define CFI_ENDPROC .cfi_endproc > #define CFI_DEF_CFA .cfi_def_cfa > @@ -22,21 +31,31 @@ > #define CFI_ESCAPE .cfi_escape > #define CFI_SIGNAL_FRAME .cfi_signal_frame > > -#ifndef BUILD_VDSO > - /* > - * Emit CFI data in .debug_frame sections, not .eh_frame sections. > - * The latter we currently just discard since we don't do DWARF > - * unwinding at runtime. So only the offline DWARF information is > - * useful to anyone. Note we should not use this directive if we > - * ever decide to enable DWARF unwinding at runtime. > - */ > - .cfi_sections .debug_frame > -#else > - /* > - * For the vDSO, emit both runtime unwind information and debug > - * symbols for the .dbg file. > - */ > - .cfi_sections .eh_frame, .debug_frame > -#endif > +#else /* !BUILD_VDSO */ > + > +/* > + * On x86, these macros aren't used outside VDSO. As well they shouldn't be: > + * they're fragile and very difficult to maintain. > + */ > + > +.macro nocfi args:vararg > +.endm > + > +#define CFI_STARTPROC nocfi > +#define CFI_ENDPROC nocfi > +#define CFI_DEF_CFA nocfi > +#define CFI_DEF_CFA_REGISTER nocfi > +#define CFI_DEF_CFA_OFFSET nocfi > +#define CFI_ADJUST_CFA_OFFSET nocfi > +#define CFI_OFFSET nocfi > +#define CFI_REL_OFFSET nocfi > +#define CFI_REGISTER nocfi > +#define CFI_RESTORE nocfi > +#define CFI_REMEMBER_STATE nocfi > +#define CFI_RESTORE_STATE nocfi > +#define CFI_UNDEFINED nocfi > +#define CFI_ESCAPE nocfi > + > +#endif /* !BUILD_VDSO */ > > #endif /* _ASM_X86_DWARF2_H */ I guess patch 3 justifies this. Acked-by: H. Peter Anvin (Intel)