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 X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C954DC2D0A3 for ; Tue, 3 Nov 2020 22:44:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 675F521534 for ; Tue, 3 Nov 2020 22:44:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="SZx8405X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730632AbgKCWoP (ORCPT ); Tue, 3 Nov 2020 17:44:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730568AbgKCWoM (ORCPT ); Tue, 3 Nov 2020 17:44:12 -0500 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFBC6C061A04 for ; Tue, 3 Nov 2020 14:44:10 -0800 (PST) Received: by mail-pl1-x644.google.com with SMTP id 1so9306517ple.2 for ; Tue, 03 Nov 2020 14:44:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=I/uB5S23puPABQIKDt8mffgwxH7OPp4NpnA8AnbObM4=; b=SZx8405XnPwkU3fqqiWAXp4mJDnmeWBjsko6l86k3D5fexc9ISIogJmm96oG5/1aEf 29ctupR0WedmDjGFqhkvtV0r48SJeFfH32j3vgJWNfUUkbKWFapu0AjIP4qbfQpViLlF jsIRWS4/TXfGHK6aooZQ9iiZN7MkGdEW8IPo/xSWFRVvFlvxgkVSiPe5MIpjATTVb46G lMKRBrufLPq8tDD+IEivQC+zRmlJbrd2ydgSFRoy+ugHS67B/LEi4H8tw2IEx3SsxxQG QWVPY5Lh1Cnga4/deGRZUD8zdjaiVmbRF1H7ah8JGD/FUMSf/LrPvqoSk6TOAKRg4qEV pTuw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=I/uB5S23puPABQIKDt8mffgwxH7OPp4NpnA8AnbObM4=; b=iQQ5VmvyeK0Nsx0X+9ZtMVdN8Palqe7NuUnzVC1jfivU7UOyKEDEcUXzwwBmOAgt6I 5aNGzDPqeX2hPyX1ZKuMcVZBB5VARFBcNukcC1E6wgfBuBLx+vi8iI9gW4tO5GhGFTSM qODWDnbn0PcP4E9/sKetCSDFYSGlQaOojSYODWiie39BJgYU8h3DU8oHsYmpuIXWe0FL 246O/AGt33J+deHuWfmHrUUDpRnUzWWdUZaYpyBhsjIETyZIoXBv47qanWtBjHXBNTWT OUr1IdvZu88TjqroxkwPUicBIWm30cwN1sTfBnnJKsip4hrzEHeEQ37pcbDWco8VG1VS 7iJw== X-Gm-Message-State: AOAM530yukvC/Uqtl5KwjoMAm6JIZHPNB9V4KVFM1EJh82tXETNZkAtd KbxlpgA+BriNZjl9i5fSptPvnmZZLYfWOGDt+Vd3mQ== X-Google-Smtp-Source: ABdhPJyoBmO3B7bFqrghvHKrH+223fIRwnGaNUGq7KGBDFFe2r2Cn+oohMtlRo2y7XucXuYg1h6zaqD2LO49AVhR42Y= X-Received: by 2002:a17:902:8ecc:b029:d6:991d:1193 with SMTP id x12-20020a1709028eccb02900d6991d1193mr22527630plo.56.1604443450113; Tue, 03 Nov 2020 14:44:10 -0800 (PST) MIME-Version: 1.0 References: <20201103012358.168682-1-maskray@google.com> <20201103014602.GA3271702@ubuntu-m3-large-x86> In-Reply-To: <20201103014602.GA3271702@ubuntu-m3-large-x86> From: Nick Desaulniers Date: Tue, 3 Nov 2020 14:43:59 -0800 Message-ID: Subject: Re: [PATCH v2] x86_64: Change .weak to SYM_FUNC_START_WEAK for arch/x86/lib/mem*_64.S To: Nathan Chancellor Cc: Fangrui Song , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , clang-built-linux , Jian Cai , Sami Tolvanen , "# 3.4.x" , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org + LKML so I can find this easier to fetch via b4 On Mon, Nov 2, 2020 at 5:46 PM Nathan Chancellor wrote: > > On Mon, Nov 02, 2020 at 05:23:58PM -0800, 'Fangrui Song' via Clang Built Linux wrote: > > Commit 393f203f5fd5 ("x86_64: kasan: add interceptors for > > memset/memmove/memcpy functions") added .weak directives to > > arch/x86/lib/mem*_64.S instead of changing the existing ENTRY macros to > > WEAK. This can lead to the assembly snippet `.weak memcpy ... .globl > > memcpy` which will produce a STB_WEAK memcpy with GNU as but STB_GLOBAL > > memcpy with LLVM's integrated assembler before LLVM 12. LLVM 12 (since > > https://reviews.llvm.org/D90108) will error on such an overridden symbol > > binding. > > > > Commit ef1e03152cb0 ("x86/asm: Make some functions local") changed ENTRY in > > arch/x86/lib/memcpy_64.S to SYM_FUNC_START_LOCAL, which was ineffective due to > > the preceding .weak directive. > > > > Use the appropriate SYM_FUNC_START_WEAK instead. > > > > Fixes: 393f203f5fd5 ("x86_64: kasan: add interceptors for memset/memmove/memcpy functions") > > Fixes: ef1e03152cb0 ("x86/asm: Make some functions local") > > Reported-by: Sami Tolvanen > > Signed-off-by: Fangrui Song > > Cc: > > This resolves the build error I see with LLVM_IAS=1 and ToT LLVM. > > Tested-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers > > > --- > > Changes in v2 > > * Correct the message: SYM_FUNC_START_WEAK was not available at commit 393f203f5fd5. > > * Mention Fixes: ef1e03152cb0 > > --- > > arch/x86/lib/memcpy_64.S | 4 +--- > > arch/x86/lib/memmove_64.S | 4 +--- > > arch/x86/lib/memset_64.S | 4 +--- > > 3 files changed, 3 insertions(+), 9 deletions(-) > > > > diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S > > index 037faac46b0c..1e299ac73c86 100644 > > --- a/arch/x86/lib/memcpy_64.S > > +++ b/arch/x86/lib/memcpy_64.S > > @@ -16,8 +16,6 @@ > > * to a jmp to memcpy_erms which does the REP; MOVSB mem copy. > > */ > > > > -.weak memcpy > > - > > /* > > * memcpy - Copy a memory block. > > * > > @@ -30,7 +28,7 @@ > > * rax original destination > > */ > > SYM_FUNC_START_ALIAS(__memcpy) > > -SYM_FUNC_START_LOCAL(memcpy) > > +SYM_FUNC_START_WEAK(memcpy) > > ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ > > "jmp memcpy_erms", X86_FEATURE_ERMS > > > > diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S > > index 7ff00ea64e4f..41902fe8b859 100644 > > --- a/arch/x86/lib/memmove_64.S > > +++ b/arch/x86/lib/memmove_64.S > > @@ -24,9 +24,7 @@ > > * Output: > > * rax: dest > > */ > > -.weak memmove > > - > > -SYM_FUNC_START_ALIAS(memmove) > > +SYM_FUNC_START_WEAK(memmove) > > SYM_FUNC_START(__memmove) > > > > mov %rdi, %rax > > diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S > > index 9ff15ee404a4..0bfd26e4ca9e 100644 > > --- a/arch/x86/lib/memset_64.S > > +++ b/arch/x86/lib/memset_64.S > > @@ -6,8 +6,6 @@ > > #include > > #include > > > > -.weak memset > > - > > /* > > * ISO C memset - set a memory block to a byte value. This function uses fast > > * string to get better performance than the original function. The code is > > @@ -19,7 +17,7 @@ > > * > > * rax original destination > > */ > > -SYM_FUNC_START_ALIAS(memset) > > +SYM_FUNC_START_WEAK(memset) > > SYM_FUNC_START(__memset) > > /* > > * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended > > -- -- Thanks, ~Nick Desaulniers