From patchwork Sun Jul 28 20:29:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Rong Xu X-Patchwork-Id: 13744050 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C850878C84 for ; Sun, 28 Jul 2024 20:30:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722198658; cv=none; b=kkeTm/nsGZzTAm/o6htOjhQWaYxDZjsnZY+DqdrsApsfcnGAETbF3ajR0/nmKEpbvX9h4mcVy2CpKdetZMDo96jvKgBH8hU5xWy+4wQQ05KdUIdm4R0J1MFrisfkdO4fK4cwM8QSoBkT/bMxRntam01Et+RG3IaJNN5ZDKDMK60= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722198658; c=relaxed/simple; bh=5P/ds+u1Nc4DlKNiDUD6ZuYs75VWIvFx1DNGM0tCz1Q=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=RAGc8xm21UQ48U3ozVYSi9S9cQ+KqBdok9QRBSHI3+cRvYOxhuDy/1Rfdrd9eBTve9o8dBRYTKUFPcUdrxxq28miYOCJyERcW6fnrEyVBtF99dBbOn2EejYW6qr4j1RTex2u9mh+Fp+/kXVKCoF0/R1fL9/thFP+NBmMbCTDdA0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--xur.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=cBfLi/ND; arc=none smtp.client-ip=209.85.215.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--xur.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="cBfLi/ND" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-7a732cdd03fso2010122a12.0 for ; Sun, 28 Jul 2024 13:30:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1722198656; x=1722803456; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=o2mnjrwU8q3IWuUcbnv2YL1wGLUV3JerNGbL3ta/V8U=; b=cBfLi/NDtBWBjPzpPP+v5+G1124d8hHZzbXbgoiu4pqz+FAKvbw9E1ZLyEQgrBXN25 QbpBDIRhwXvjGIFkLpOyTIhPDblH6z/L1doVuTsiqPZBd3276WcIB7fjno5tWbyx2LVp o68jtHuRaLpUhnyQpxWw/xwyAg+WMpY61e+epj7knLvBbskeNjDP3nsirkhsx/Uhe9SK cmvyKn7Jm0OiGkRZf/q5fyR1FTwd5Hz+yuctGrsZsUQCxLf1Y1wEd50xCsjePOvSawfc btR56IofvZ/TgXqTUer2V6Vh4qKhnwGLvDoQerI4gDdZzE1I6CVclK+x3p6QTbCmJgC7 dH1w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722198656; x=1722803456; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=o2mnjrwU8q3IWuUcbnv2YL1wGLUV3JerNGbL3ta/V8U=; b=WTTw+f9Y8tFLZg3Y/jr9jBYyDhiOZYnoqhLAXmG9jQEXzdsDkDMzTpsoHnKhuErSeR YPmd/wom8alm5GIpmIl8iXls66ZVNr9p3CwtKLy/rmoqpGadQqJRyHHwhg1xxlXz9lZB 56VdNplcN+jDON8tojKw0ufZykQu4cS523PX0atXPvIS0hpMN876s1mf4NhL4bst+9nB aifFjjbufzNMcunsGgSVJDaXIoFiknKhj7143htmjUAC4IGCQNf7el24kyMLO61RE8eX S2kU9Xn4JXlVz6330Ju/q8jZzLq/Iso/+mXrX6ESu06LNUMWD/+vdD8bZkXdOozQ8vMc os8g== X-Forwarded-Encrypted: i=1; AJvYcCURtK9HkHARF4S7AS7xhBO5oKRyuD10I/J3Jy/6h6TSQES0QiPbO5fQGlmwdfWaTXpHb9onY9n64yQjH5rU1IWpNeRNxZV3iPSMt0oQ X-Gm-Message-State: AOJu0YyOJuTPIuQG2ON9S0FIalU0YYGiQYCO52x1Iv4JOw81FnXu7Q0w vm5PCo2rvMoIqdBFtiEo0YsqrV9/r7OIvxJ6X+qw09MnFUmZ4hsFCIuv6/W4E0k2FA== X-Google-Smtp-Source: AGHT+IF+cnWDEef0AOr5iV5UnZQ0Nmg6qihUgkJJVOtSeHchBxmd2+NRGmp/GGHZSyrSRRs3cz4mBGg= X-Received: from xur.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:2330]) (user=xur job=sendgmr) by 2002:a63:e903:0:b0:75c:49a4:2a2c with SMTP id 41be03b00d2f7-7ac8f942a86mr12318a12.7.1722198655784; Sun, 28 Jul 2024 13:30:55 -0700 (PDT) Date: Sun, 28 Jul 2024 13:29:56 -0700 In-Reply-To: <20240728203001.2551083-1-xur@google.com> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240728203001.2551083-1-xur@google.com> X-Mailer: git-send-email 2.46.0.rc1.232.g9752f9e123-goog Message-ID: <20240728203001.2551083-4-xur@google.com> Subject: [PATCH 3/6] Change the symbols order when --ffuntion-sections is enabled From: Rong Xu To: Rong Xu , Han Shen , Sriraman Tallam , David Li , Jonathan Corbet , Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Ard Biesheuvel , Arnd Bergmann , Josh Poimboeuf , Peter Zijlstra , Nick Desaulniers , Bill Wendling , Justin Stitt , Vegard Nossum , John Moon , Andrew Morton , Heiko Carstens , Luis Chamberlain , Samuel Holland , Mike Rapoport , "Paul E . McKenney" , Rafael Aquini , Petr Pavlu , Eric DeVolder , Bjorn Helgaas , Randy Dunlap , Benjamin Segall , Breno Leitao , Wei Yang , Brian Gerst , Juergen Gross , Palmer Dabbelt , Alexandre Ghiti , Kees Cook , Sami Tolvanen , Xiao Wang , Jan Kiszka Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-efi@vger.kernel.org, linux-arch@vger.kernel.org, llvm@lists.linux.dev, Krzysztof Pszeniczny When the -ffunction-sections compiler option is enabled, each function is placed in a separate section named .text.function_name rather than putting all functions in a single .text section. However, using -function-sections can cause problems with the linker script. The comments included in include/asm-generic/vmlinux.lds.h note these issues.: “TEXT_MAIN here will match .text.fixup and .text.unlikely if dead code elimination is enabled, so these sections should be converted to use ".." first.” It is unclear whether there is a straightforward method for converting a suffix to "..". This patch modifies the order of subsections within the text output section when the -ffunction-sections flag is enabled. Specifically, it repositions sections with certain fixed patterns (for example .text.unlikely) before TEXT_MAIN, ensuring that they are grouped and matched together. Note that the limitation arises because the linker script employs glob patterns instead of regular expressions for string matching. While there is a method to maintain the current order using complex patterns, this significantly complicates the pattern and increases the likelihood of errors. Co-developed-by: Han Shen Signed-off-by: Han Shen Signed-off-by: Rong Xu Suggested-by: Sriraman Tallam Suggested-by: Krzysztof Pszeniczny --- include/asm-generic/vmlinux.lds.h | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 5703526d6ebf..f3de66bda293 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -582,9 +582,21 @@ * during second ld run in second ld pass when generating System.map * * TEXT_MAIN here will match .text.fixup and .text.unlikely if dead - * code elimination is enabled, so these sections should be converted - * to use ".." first. + * code elimination or function-section is enabled. Match these symbols + * first when in these builds. */ +#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG) +#define TEXT_TEXT \ + *(.text.asan.* .text.tsan.*) \ + *(.text.unknown .text.unknown.*) \ + *(.text.unlikely .text.unlikely.*) \ + ALIGN_FUNCTION(); \ + *(.text.hot .text.hot.*) \ + *(TEXT_MAIN .text.fixup) \ + NOINSTR_TEXT \ + *(.ref.text) \ + MEM_KEEP(init.text*) +#else #define TEXT_TEXT \ ALIGN_FUNCTION(); \ *(.text.hot .text.hot.*) \ @@ -594,7 +606,8 @@ NOINSTR_TEXT \ *(.ref.text) \ *(.text.asan.* .text.tsan.*) \ - MEM_KEEP(init.text*) \ + MEM_KEEP(init.text*) +#endif /* sched.text is aling to function alignment to secure we have same