From patchwork Fri Aug 26 18:10:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nick Desaulniers X-Patchwork-Id: 12956381 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20DFEECAAA3 for ; Fri, 26 Aug 2022 18:10:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344960AbiHZSKz (ORCPT ); Fri, 26 Aug 2022 14:10:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344980AbiHZSKy (ORCPT ); Fri, 26 Aug 2022 14:10:54 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89E4DBD0BE for ; Fri, 26 Aug 2022 11:10:53 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-33da75a471cso36828377b3.20 for ; Fri, 26 Aug 2022 11:10:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc; bh=y85OHCHx+Vi/sO7g73ubX7Iq+I1fFfBENt1UsLJJtEY=; b=Wj6HCEjnqrM+ctPXZ7KiGzIXUgQPn1aBBzqlXzJXgi4UZbJJxcgs2UwkHjll+zpoDb QeMdKfqcbQOVp17Y0+gesDEiIBE2NtsbSzBeish3QzVjv+ccDr8N9iBPhNlnJ+YXJgXc TvKwx7H5srQaXdmnL0HXDThn+fsOePUCjTuCn0aigqKEnJMlv7h1Xp+qfv8qoTynWxqI 4txto8tzY+q23E3IEn+vhGNU4fNuv5wFW3EC0z2YsZ+kLvCz3/6YommEVb33Y4oEwDD3 0L4yDniY0aGOCZ6n2IM+1XskuCSVe+ByexHFTTMple1/llBbEl7kTK+daJJISfnFHL6d TeaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc; bh=y85OHCHx+Vi/sO7g73ubX7Iq+I1fFfBENt1UsLJJtEY=; b=Vv8FReG3NuZx8SeadgRniGEZNRspiLjYmorgV1kqYnApT1FMsKlq5PQljsvREu90NW 38eVMGy+E3w/uPUa6qF0EPoYli88mtfLAxPBKcTJ40P5wEqzw2+7SSzZEr4btp/ihEHa KIx4QU3DkV4MikDm7Ey0lHOFk5NXfPMR1DdSGVV4idNtnprqyyRHASXrsB4F4KBs3UtQ FxxaeFyUtvbqYpymblF8dU+AFDLUVAPTfr5bT0NGct89ugOGX4cgXHt0p4uqQij70TjZ ayRwS6dhezwtd04NeHtNk3yW48bsft2WeuVaLp+kPS1i4E2FjLwgLCB22EpFdG6/3J6L cOsw== X-Gm-Message-State: ACgBeo0Xvrccz0pL7Bn1YGxFU4aTBv62gq8lWftjt7/W1pHAL6AuVl1K +cD2X7powywT7/cHoGLS6LSCLw0pSZlKRPAA99s= X-Google-Smtp-Source: AA6agR5OzcKIoYCg9NU/S1Bt4QZM/GluQ1lilTqv2NoDx2SVtJGQ0ZZoyYauXUteYnrMqBae+wpkPcsEDZ5Oc9etZfQ= X-Received: from ndesaulniers1.mtv.corp.google.com ([2620:0:100e:712:8d7b:b933:5438:2a88]) (user=ndesaulniers job=sendgmr) by 2002:a05:6902:124f:b0:66e:e3da:487e with SMTP id t15-20020a056902124f00b0066ee3da487emr973177ybu.310.1661537452858; Fri, 26 Aug 2022 11:10:52 -0700 (PDT) Date: Fri, 26 Aug 2022 11:10:34 -0700 In-Reply-To: <20220826181035.859042-1-ndesaulniers@google.com> Mime-Version: 1.0 References: <20220826181035.859042-1-ndesaulniers@google.com> X-Developer-Key: i=ndesaulniers@google.com; a=ed25519; pk=lvO/pmg+aaCb6dPhyGC1GyOCvPueDrrc8Zeso5CaGKE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1661537435; l=3096; i=ndesaulniers@google.com; s=20211004; h=from:subject; bh=WJicEEw1ygkDh8L4szHogyorYbivCBDQ7W9ZrvdhNOc=; b=ZWuPxn7dhLiVcgTrvuHdUAPAmyqC6WoqmU5iSPWfVYPAWJqjwzpjYxl1614lFrA0/+q4/P3onXk1 O00OgL5BCi40Z6C06mizSDk06M74HD6otU8B3ZzdiYDlMTNMCJLe X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220826181035.859042-3-ndesaulniers@google.com> Subject: [PATCH 2/3] Makefile.debug: re-enable debug info for .S files From: Nick Desaulniers To: Masahiro Yamada Cc: Michal Marek , Nathan Chancellor , Tom Rix , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, x86@kernel.org, Dmitrii Bundin , Fangrui Song , Alexey Alexandrov , Bill Wendling , Greg Thelen , Nick Desaulniers Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Alexey reported that the fraction of unknown filename instances in kallsyms grew from ~0.3% to ~10% recently; Bill and Greg tracked it down to assembler defined symbols, which regressed as a result of: commit b8a9092330da ("Kbuild: do not emit debug info for assembly with LLVM_IAS=1") In that commit, I allude to restoring debug info for assembler defined symbols in a follow up patch, but it seems I forgot to do so in commit a66049e2cf0e ("Kbuild: make DWARF version a choice") This patch does a few things: 1. Add -g to KBUILD_AFLAGS. This will instruct the compiler to instruct the assembler to emit debug info. But this can cause an issue for folks using a newer compiler but older assembler, because the implicit default DWARF version changed from v4 to v5 in gcc-11 and clang-14. 2. If the user is using CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT, use a version check to explicitly set -Wa,-gdwarf- for the assembler. There's another problem with this; GAS only gained support for explicit DWARF versions 3-5 in the 2.36 GNU binutils release. 3. Wrap -Wa,-gdwarf- in as-option call to test whether the assembler supports that explicit DWARF version. Link: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=31bf18645d98b4d3d7357353be840e320649a67d Fixes: b8a9092330da ("Kbuild: do not emit debug info for assembly with LLVM_IAS=1") Reported-by: Alexey Alexandrov Reported-by: Bill Wendling Reported-by: Greg Thelen Signed-off-by: Nick Desaulniers --- scripts/Makefile.debug | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug index 9f39b0130551..a7a6da7f6e7d 100644 --- a/scripts/Makefile.debug +++ b/scripts/Makefile.debug @@ -4,18 +4,32 @@ ifdef CONFIG_DEBUG_INFO_SPLIT DEBUG_CFLAGS += -gsplit-dwarf else DEBUG_CFLAGS += -g +KBUILD_AFLAGS += -g endif -ifndef CONFIG_AS_IS_LLVM -KBUILD_AFLAGS += -Wa,-gdwarf-2 +ifdef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT +# gcc-11+, clang-14+ +ifeq ($(shell [ $(CONFIG_GCC_VERSION) -ge 110000 -o $(CONFIG_CLANG_VERSION) -ge 140000 ] && echo y),y) +dwarf-version-y := 5 +else +dwarf-version-y := 4 endif - -ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT +else # !CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4 dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5 DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y) endif +# Binutils 2.35+ (or clang) required for -gdwarf-{4|5}. +# https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=31bf18645d98b4d3d7357353be840e320649a67d +ifneq ($(call as-option,-Wa$(comma)-gdwarf-$(dwarf-version-y)),) +KBUILD_AFLAGS += -Wa,-gdwarf-$(dwarf-version-y) +else +ifndef CONFIG_AS_IS_LLVM +KBUILD_AFLAGS += -Wa,-gdwarf-2 +endif +endif + ifdef CONFIG_DEBUG_INFO_REDUCED DEBUG_CFLAGS += -fno-var-tracking ifdef CONFIG_CC_IS_GCC