From patchwork Tue Oct 13 00:31:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11834795 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AFCE3109B for ; Tue, 13 Oct 2020 02:45:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93C0420678 for ; Tue, 13 Oct 2020 02:45:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="RWGnAnvd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727215AbgJMAdX (ORCPT ); Mon, 12 Oct 2020 20:33:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727535AbgJMAdB (ORCPT ); Mon, 12 Oct 2020 20:33:01 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90B8EC0613DD for ; Mon, 12 Oct 2020 17:32:33 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id k9so8529270ybf.18 for ; Mon, 12 Oct 2020 17:32:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=i0HfMD/wRChzzw+H0j5SIQI+XYlsyfomuEvjB0A2b7U=; b=RWGnAnvd5Lp76tMdFpNH1+zuCs711HvTmjeeqWExWdLO0b+IYvl8hseJy7bQVsA/yQ WbWgdjz9odSgS33tA7SyJrG23HtPbcQQ2sqTeDLN0z+XNW/U1+B04f29pxuTIBAo0Bwr 1kuUI0qew0RRwWEdSqeHxrYPCuM0lKcyAQQHVJyqk0NDK5lndU4kJ0nEntK7Gw/b+6ds NINAxQFY1xV9pWKvIAxegfc8BATcwAptMc23jyb2HlWegaJKMJtRw94gvpud1QRadkKB gA/bzBYbBksOIuoqgqduz/XaFVcQDSEIQm1NvRkC4MArUYBfjsPwupbm8iuKYDaYWWMx dfRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=i0HfMD/wRChzzw+H0j5SIQI+XYlsyfomuEvjB0A2b7U=; b=eesqIejoamLCDqGu8hExJpsCGoA07sPRW+hR/Xoh+bFd3m3167CbMEnSlx+2MjKNSM gJg7Zz4AWi9vhAQ2hS00hqGVenSBNvn1JEqJWxsJzPwXwJgW52M+abr/kYVLh5l+QUIE Jm1I8RsPlr5PDHEXZJITjCJN7HqWNHlpgVwK//ciBpk8EyO2yoNQzOpRgGnBbEvstoaI arMAyNuprtYHNerL8Xd2tuvOnLfKwTuyWrHfrSk5mnIHXzue4nVKbZBXQVR3EJqTnHOH sSXWu3N9ODy8Fr39I5TIcH30HogEwl2vRGaVotYvpwv8kDNIUSulGstrMJDgAGbA+wKI TX9Q== X-Gm-Message-State: AOAM533Ik+hn9RkNeQRkZaUYFnQ/x7YO/rvYIa/evFfTw3qPuxP/nc+J 8taXQMaVUGFrvosg1rZLmVlRy0mOWViYTps/ZQM= X-Google-Smtp-Source: ABdhPJyWpX0TYRebf3Rkf2Yh1c8ADAskEKEgvpC4cZTbopj2J6pmYFQCkigTg2srbz/p2P1Qt1W0jVbIt5KqdOEhaLA= Sender: "samitolvanen via sendgmr" X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:f693:9fff:fef4:1b6d]) (user=samitolvanen job=sendgmr) by 2002:a25:cc89:: with SMTP id l131mr12649555ybf.154.1602549152704; Mon, 12 Oct 2020 17:32:32 -0700 (PDT) Date: Mon, 12 Oct 2020 17:31:51 -0700 In-Reply-To: <20201013003203.4168817-1-samitolvanen@google.com> Message-Id: <20201013003203.4168817-14-samitolvanen@google.com> Mime-Version: 1.0 References: <20201013003203.4168817-1-samitolvanen@google.com> X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v6 13/25] kbuild: lto: merge module sections From: Sami Tolvanen To: Masahiro Yamada , Steven Rostedt Cc: Will Deacon , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org LLD always splits sections with LTO, which increases module sizes. This change adds linker script rules to merge the split sections in the final module. Suggested-by: Nick Desaulniers Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- scripts/module.lds.S | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/scripts/module.lds.S b/scripts/module.lds.S index 69b9b71a6a47..037120173a22 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -25,5 +25,33 @@ SECTIONS { __jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) } } +#ifdef CONFIG_LTO_CLANG +/* + * With CONFIG_LTO_CLANG, LLD always enables -fdata-sections and + * -ffunction-sections, which increases the size of the final module. + * Merge the split sections in the final binary. + */ +SECTIONS { + __patchable_function_entries : { *(__patchable_function_entries) } + + .bss : { + *(.bss .bss.[0-9a-zA-Z_]*) + *(.bss..L*) + } + + .data : { + *(.data .data.[0-9a-zA-Z_]*) + *(.data..L*) + } + + .rodata : { + *(.rodata .rodata.[0-9a-zA-Z_]*) + *(.rodata..L*) + } + + .text : { *(.text .text.[0-9a-zA-Z_]*) } +} +#endif + /* bring in arch-specific sections */ #include