From patchwork Sun Oct 28 13:09:42 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Changbin Du X-Patchwork-Id: 10658619 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1540A109C for ; Sun, 28 Oct 2018 13:10:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 05C2D29DA3 for ; Sun, 28 Oct 2018 13:10:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EDEFC29DD5; Sun, 28 Oct 2018 13:10:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5768329DA3 for ; Sun, 28 Oct 2018 13:10:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727679AbeJ1VzF (ORCPT ); Sun, 28 Oct 2018 17:55:05 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:43267 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726548AbeJ1VzF (ORCPT ); Sun, 28 Oct 2018 17:55:05 -0400 Received: by mail-pl1-f195.google.com with SMTP id 30-v6so2516813plb.10; Sun, 28 Oct 2018 06:10:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Hk0Di9Qb+zs88OQ4I5uk9OIJ44YMozS+eSEHj+aJ9Z0=; b=DULrqDVbYreYAt1oKKC5KgMOg6D5NXd/8T9BEROdYj6TkIU2HY30/P/DGiMiC14ufk o3AFsrfDOdGoxj/rkJm14rSK6bmINopwt3Hzq/Kg1duxBokx79pObjNY8Y8rME7o9YZ0 Vr5jeGR7C/fPLJipN6wWiqX17b0VIxAftL54IC2Fu7QrPgeplkHgwzrdXqeCRTTQxYfA nmNDD/O4bKqqV7GY4sPM69rZMSwnjT5d5+3+gIniBJD1egbzijp8Wt2s8VxM0dqaoOxr oPDKfIBPItQd9HyqT/bFwP168d263K6nG7SYQSkYBkK1krUhpb91xE6HdlAyTvTfe07M czZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=Hk0Di9Qb+zs88OQ4I5uk9OIJ44YMozS+eSEHj+aJ9Z0=; b=GJtW9PIrkgqHHqnQVIZbfrdXW7GLGCqT80sddeYgHLlHtnMc77ZRjyUImOAA7hNb/n MxmW3CS+du87ttNxVCdw3cUvT7E2EPa85u+rUGaKisVV6/zO6wgMbYB8naZO0P3ENqhQ t2qX3jqzwSatqs6nHMJNQqW++q5vGOxLPHiT6rdFoXd2zKVubynSiiBRWEWlDElsiKLh M+Obo6T33Kmo+hXQdGPnmQcUwZY71M0jnVAnu3JHtMSwom1Iz/I8CU5L7MCuFDdHUJNw +ygjWiADH4Feu0QJq3NVL4ttXLEw18KyEmTE7zgFAlFglWsSsoM3XNBKqBgSoFYylEiq JpMA== X-Gm-Message-State: AGRZ1gJ8Sb/ibjyLjSXifehlM2VAvFXxElrI8be7zxDU/FJyr9/Rhgbs QE5rpyq16Aanu4uWGQ613OA= X-Google-Smtp-Source: AJdET5dlcd9UXIUBLCS603gJym1Rp6+h0wVdPcUWTt9ebbUn43Wir4lzeAXgOyGgOH1LsevXat6yJg== X-Received: by 2002:a17:902:d806:: with SMTP id a6-v6mr10148394plz.301.1540732228780; Sun, 28 Oct 2018 06:10:28 -0700 (PDT) Received: from vultr.guest ([2001:19f0:6001:4ff6:5400:1ff:feb7:a195]) by smtp.gmail.com with ESMTPSA id e3-v6sm24520585pgc.71.2018.10.28.06.10.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Oct 2018 06:10:28 -0700 (PDT) From: Changbin Du To: yamada.masahiro@socionext.com, michal.lkml@markovi.net, tglx@linutronix.de, mingo@redhat.com, linux@armlinux.org.uk, akpm@linux-foundation.org, gregkh@linuxfoundation.org Cc: rostedt@goodmis.org, x86@kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, robin.murphy@arm.com, Changbin Du Subject: [PATCH v3 1/4] x86/mm: declare check_la57_support() as inline Date: Sun, 28 Oct 2018 13:09:42 +0000 Message-Id: <20181028130945.23581-2-changbin.du@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181028130945.23581-1-changbin.du@gmail.com> References: <20181028130945.23581-1-changbin.du@gmail.com> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The level4_kernel_pgt is only defined when X86_5LEVEL is enabled. So declare check_la57_support() as inline to make sure the code referring to level4_kernel_pgt is optimized out. This is a preparation for CONFIG_CC_OPTIMIZE_FOR_DEBUGGING. Signed-off-by: Changbin Du Cc: Steven Rostedt (VMware) Cc: Masahiro Yamada Reviewed-by: Steven Rostedt (VMware) --- arch/x86/kernel/head64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 5dc377dc9d7b..5ae682f2aa83 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -98,7 +98,7 @@ static bool __head check_la57_support(unsigned long physaddr) return true; } #else -static bool __head check_la57_support(unsigned long physaddr) +static inline bool __head check_la57_support(unsigned long physaddr) { return false; } From patchwork Sun Oct 28 13:09:43 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Changbin Du X-Patchwork-Id: 10658617 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4C23A109C for ; Sun, 28 Oct 2018 13:10:54 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3EAE129D89 for ; Sun, 28 Oct 2018 13:10:54 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3CA9C29DA3; Sun, 28 Oct 2018 13:10:54 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DE0DB29D92 for ; Sun, 28 Oct 2018 13:10:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727702AbeJ1VzH (ORCPT ); Sun, 28 Oct 2018 17:55:07 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:33333 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726548AbeJ1VzH (ORCPT ); Sun, 28 Oct 2018 17:55:07 -0400 Received: by mail-pg1-f196.google.com with SMTP id z2-v6so2609763pgp.0; Sun, 28 Oct 2018 06:10:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Z1p1Mx8pgPnws2nPs4SRISeGm4KePLjEigb8toAYrzc=; b=p70glEk2yIucDRr40/8Hr1khRVVKJNRIDH5GYhj9Q0/g7Z+dOkKBVaZDZ98t6IJVCJ PbD7er//t9LHVRYB+C+YEoVZxlBecTg0kl1EW6Twv3wswZJpD8oSpcg+jPxjUdhyJpYh 8NkSxTYPKy8bEh2LBgb6Vcc6HIwzHsPvuBmx6Wwld/2KZ+53cQEzhCRQXA77xVT5pI3P QsbNUdTF83/EGw2ZGg8xiNLqirLreNo6qGh9OX/M6aGnbuyXebaamKkU/aovLXC1AhLF pHUiSumZHFKjHAwx+8wzEmX8XkqwufG1Mj+Qt5FiDDQPLHZ1aSpF/K13FXu5JIkdMUjb mWZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=Z1p1Mx8pgPnws2nPs4SRISeGm4KePLjEigb8toAYrzc=; b=Cx5qS+sLKulpYl0EUP/JLTjMw3m89px+tVZ1yj2pTxZxUydJlaTLA/OAue+gRb8+cP aN++YJgG/9CWzHmA8FoF1avnTbNOJWNYd9T2kybmOgSpgfs8l4QAWmdeGZlo49amFa7L 4B+l/AsnqHDdC667p5TQNcqoGJWYY47EqFL3NuPN0DrlY9WAnDO060Vjcbz64nb/srNB OzPKtOAMLYSSNFgV58+L7GBNxbhJ+n2pZebM+Wu7CsUo+8vh4SaPVobddQUYOKqhSCpA SZKuHTmyic+BfDoBcOKRMA6dxWW4Cvwtf8R0omYvtlujuQnTOmrZNvMTYBJJ+Dp0Jv8D 9ytw== X-Gm-Message-State: AGRZ1gKT6a5FGI37zIX350rSV4zTdf/M9E5AF3d0mqQT0iNdYcpavw+j uUsVOFo60rCYgtlMDVZgoKw= X-Google-Smtp-Source: AJdET5cLbwkXzA9J08vC2kuEb0XRP43sQtDazJtqPYG0V2E1TwCUeCXE6abOHRLPKtZT9JI1faLr9g== X-Received: by 2002:a65:56cc:: with SMTP id w12-v6mr9868447pgs.224.1540732230956; Sun, 28 Oct 2018 06:10:30 -0700 (PDT) Received: from vultr.guest ([2001:19f0:6001:4ff6:5400:1ff:feb7:a195]) by smtp.gmail.com with ESMTPSA id e3-v6sm24520585pgc.71.2018.10.28.06.10.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Oct 2018 06:10:30 -0700 (PDT) From: Changbin Du To: yamada.masahiro@socionext.com, michal.lkml@markovi.net, tglx@linutronix.de, mingo@redhat.com, linux@armlinux.org.uk, akpm@linux-foundation.org, gregkh@linuxfoundation.org Cc: rostedt@goodmis.org, x86@kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, robin.murphy@arm.com, Changbin Du Subject: [PATCH v3 2/4] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations Date: Sun, 28 Oct 2018 13:09:43 +0000 Message-Id: <20181028130945.23581-3-changbin.du@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181028130945.23581-1-changbin.du@gmail.com> References: <20181028130945.23581-1-changbin.du@gmail.com> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch add a new kernel hacking option NO_AUTO_INLINE. Selecting this option will prevent the compiler from optimizing the kernel by auto-inlining functions not marked with the inline keyword. With this option, only functions explicitly marked with "inline" will be inlined. This will allow the function tracer to trace more functions because it only traces functions that the compiler has not inlined. Signed-off-by: Changbin Du Acked-by: Steven Rostedt (VMware) --- Makefile | 6 ++++++ lib/Kconfig.debug | 17 +++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/Makefile b/Makefile index 7d4ba5196010..04beb822ddfc 100644 --- a/Makefile +++ b/Makefile @@ -749,6 +749,12 @@ KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \ $(call cc-option,-fno-var-tracking) endif +ifdef CONFIG_NO_AUTO_INLINE +KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions) \ + $(call cc-option, -fno-inline-small-functions) \ + $(call cc-option, -fno-inline-functions-called-once) +endif + ifdef CONFIG_FUNCTION_TRACER ifdef CONFIG_FTRACE_MCOUNT_RECORD # gcc 5 supports generating the mcount tables directly diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 04adfc3b185e..d50711b41dad 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -211,6 +211,23 @@ config GDB_SCRIPTS instance. See Documentation/dev-tools/gdb-kernel-debugging.rst for further details. +config NO_AUTO_INLINE + bool "Disable compiler auto-inline optimizations" + help + This will prevent the compiler from optimizing the kernel by + auto-inlining functions not marked with the inline keyword. + With this option, only functions explicitly marked with + "inline" will be inlined. This will allow the function tracer + to trace more functions because it only traces functions that + the compiler has not inlined. + + Enabling this function can help debugging a kernel if using + the function tracer. But it can also change how the kernel + works, because inlining functions may change the timing, + which could make it difficult while debugging race conditions. + + If unsure, select N. + config ENABLE_MUST_CHECK bool "Enable __must_check logic" default y From patchwork Sun Oct 28 13:09:44 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Changbin Du X-Patchwork-Id: 10658615 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D3C13109C for ; Sun, 28 Oct 2018 13:10:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C4B8D29CF7 for ; Sun, 28 Oct 2018 13:10:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B8C0A29D9E; Sun, 28 Oct 2018 13:10:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6E40129DA3 for ; Sun, 28 Oct 2018 13:10:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727727AbeJ1VzK (ORCPT ); Sun, 28 Oct 2018 17:55:10 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:42512 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726548AbeJ1VzJ (ORCPT ); Sun, 28 Oct 2018 17:55:09 -0400 Received: by mail-pl1-f193.google.com with SMTP id t6-v6so2522519plo.9; Sun, 28 Oct 2018 06:10:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Kpqpa9BZU+OQvUZEt5EjgcpLDGJ7LYzg33W/0iJP1IU=; b=GzZBW3iQRzy1++L2+rMly7s+XGO5sCf2vm2L80QHemKPNXtqraC4vZZ78TMuSVzlmV EK9B4sQzrNxqG7VfdNIWBFWkVWe/YiE0MrGGSuMAZX2LdWFOCfQVy06ZLXD+LQG2w81n BqDeA1KNTRBenQCn1rsGJm3nQHDvPzcY4osxub8JEa5qgqe3MkswskHz1DL0vEAAL1Fa rEOp850CBTZClZ15ATK3l0PFz/AnpNlygwcDe//XCybQ9AgP3OX1ZnPhYya17m8JCTEF CM+JPtT32FzyNpTawHK/WQ+nBQFYWyd+8hQT0xDOPix/EJ0kl+9x4qGk0EYSd1zjq09d oWXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=Kpqpa9BZU+OQvUZEt5EjgcpLDGJ7LYzg33W/0iJP1IU=; b=QyabcIT4bdiAlYN1K+B1tK2iJxThgnOjPPEDAdHuQGv+Ii72T4fS9rZ+uOrIYVH/lQ ADESQSDg06F8C3gu6Lt1/rLg+ig7d+jBItj5G4oH3EpbNeEaI2zAHyKvujQZmFtSQRhE XLgRK5soRoWE8Y7KcpuFYjyJyeZ7mvdKoBgaZaiE7HYfNg3LsrIrMHRSXhPWzaTkzHbZ zMm1QrCBC7By/EM5qG3BdA1r3jXtiPiLwjUkRHJa6IrPymvmTsIHXhJErBHOMC0K4AZ+ 8CX07UenqET/7CuvsBodDn50i05Nk7nMBHeoKIIwK8rBvm9vrzb4P/QE4F0ugtjs5XTC L6sw== X-Gm-Message-State: AGRZ1gJ4f9ORrdF0f1f7FguQUYMGPH+TSvjJmwBKSbpTTvE1BLBywa7i 2SPTJqnIhncTXk/c+mTNoKQ= X-Google-Smtp-Source: AJdET5cpZ64yhtGBXP9CJqPAYJ3I+V+dhlwUfEuT7gKrAtWFQu4MGKpcSsX18AOmD+ciiU5xq6IHLQ== X-Received: by 2002:a17:902:9a07:: with SMTP id v7-v6mr10240898plp.14.1540732233035; Sun, 28 Oct 2018 06:10:33 -0700 (PDT) Received: from vultr.guest ([2001:19f0:6001:4ff6:5400:1ff:feb7:a195]) by smtp.gmail.com with ESMTPSA id e3-v6sm24520585pgc.71.2018.10.28.06.10.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Oct 2018 06:10:32 -0700 (PDT) From: Changbin Du To: yamada.masahiro@socionext.com, michal.lkml@markovi.net, tglx@linutronix.de, mingo@redhat.com, linux@armlinux.org.uk, akpm@linux-foundation.org, gregkh@linuxfoundation.org Cc: rostedt@goodmis.org, x86@kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, robin.murphy@arm.com, Changbin Du Subject: [PATCH v3 3/4] ARM: mm: fix build error in fix_to_virt with CONFIG_CC_OPTIMIZE_FOR_DEBUGGING Date: Sun, 28 Oct 2018 13:09:44 +0000 Message-Id: <20181028130945.23581-4-changbin.du@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181028130945.23581-1-changbin.du@gmail.com> References: <20181028130945.23581-1-changbin.du@gmail.com> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP With '-Og' optimization level, GCC would not optimize a count for a loop as a constant value. But BUILD_BUG_ON() only accept compile-time constant values. Let's use __fix_to_virt() to avoid the error. arch/arm/mm/mmu.o: In function `fix_to_virt': /home/changbin/work/linux/./include/asm-generic/fixmap.h:31: undefined reference to `__compiletime_assert_31' Makefile:1051: recipe for target 'vmlinux' failed make: *** [vmlinux] Error 1 Signed-off-by: Changbin Du Acked-by: Steven Rostedt (VMware) --- arch/arm/mm/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index e46a6a446cdd..c08d74e76714 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -1599,7 +1599,7 @@ static void __init early_fixmap_shutdown(void) pte_t *pte; struct map_desc map; - map.virtual = fix_to_virt(i); + map.virtual = __fix_to_virt(i); pte = pte_offset_early_fixmap(pmd_off_k(map.virtual), map.virtual); /* Only i/o device mappings are supported ATM */ From patchwork Sun Oct 28 13:09:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Changbin Du X-Patchwork-Id: 10658609 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2E6D81751 for ; 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Sun, 28 Oct 2018 06:10:35 -0700 (PDT) Received: from vultr.guest ([2001:19f0:6001:4ff6:5400:1ff:feb7:a195]) by smtp.gmail.com with ESMTPSA id e3-v6sm24520585pgc.71.2018.10.28.06.10.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 28 Oct 2018 06:10:34 -0700 (PDT) From: Changbin Du To: yamada.masahiro@socionext.com, michal.lkml@markovi.net, tglx@linutronix.de, mingo@redhat.com, linux@armlinux.org.uk, akpm@linux-foundation.org, gregkh@linuxfoundation.org Cc: rostedt@goodmis.org, x86@kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, robin.murphy@arm.com, Changbin Du Subject: [PATCH v3 4/4] kernel hacking: new config CC_OPTIMIZE_FOR_DEBUGGING to apply GCC -Og optimization Date: Sun, 28 Oct 2018 13:09:45 +0000 Message-Id: <20181028130945.23581-5-changbin.du@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181028130945.23581-1-changbin.du@gmail.com> References: <20181028130945.23581-1-changbin.du@gmail.com> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This will apply GCC '-Og' optimization level which is supported since GCC 4.8. This optimization level offers a reasonable level of optimization while maintaining fast compilation and a good debugging experience. It is similar to '-O1' while perferring to keep debug ability over runtime speed. If enabling this option breaks your kernel, you should either disable this or find a fix (mostly in the arch code). Currently this option has only been tested on x86_64 and arm platform. This option can satisfy people who was searching for a method to disable compiler optimizations so to achieve better kernel debugging experience with kgdb or qemu. The main problem of '-Og' is we must not use __attribute__((error(msg))). The compiler will report error though the call to error function still can be optimize out. So we must fallback to array tricky. Comparison of vmlinux size: a bit smaller. w/o CONFIG_CC_OPTIMIZE_FOR_DEBUGGING $ size vmlinux text data bss dec hex filename 22665554 9709674 2920908 35296136 21a9388 vmlinux w/ CONFIG_CC_OPTIMIZE_FOR_DEBUGGING $ size vmlinux text data bss dec hex filename 21499032 10102758 2920908 34522698 20ec64a vmlinux Comparison of system performance: a bit drop (~6%). This benchmark of kernel compilation is suggested by Ingo Molnar. https://lkml.org/lkml/2018/5/2/74 Preparation: Set cpufreq to 'performance'. for ((cpu=0; cpu<120; cpu++)); do G=/sys/devices/system/cpu/cpu$cpu/cpufreq/scaling_governor [ -f $G ] && echo performance > $G done w/o CONFIG_CC_OPTIMIZE_FOR_DEBUGGING $ perf stat --repeat 5 --null --pre '\ cp -a kernel ../kernel.copy.$(date +%s); \ rm -rf *; \ git checkout .; \ echo 1 > /proc/sys/vm/drop_caches; \ find ../kernel* -type f | xargs cat >/dev/null; \ make -j kernel >/dev/null; \ make clean >/dev/null 2>&1; \ sync '\ \ make -j8 >/dev/null Performance counter stats for 'make -j8' (5 runs): 219.764246652 seconds time elapsed ( +- 0.78% ) w/ CONFIG_CC_OPTIMIZE_FOR_DEBUGGING $ perf stat --repeat 5 --null --pre '\ cp -a kernel ../kernel.copy.$(date +%s); \ rm -rf *; \ git checkout .; \ echo 1 > /proc/sys/vm/drop_caches; \ find ../kernel* -type f | xargs cat >/dev/null; \ make -j kernel >/dev/null; \ make clean >/dev/null 2>&1; \ sync '\ \ make -j8 >/dev/null Performance counter stats for 'make -j8' (5 runs): 233.574187771 seconds time elapsed ( +- 0.19% ) Signed-off-by: Changbin Du Acked-by: Steven Rostedt (VMware) Cc: Masahiro Yamada --- v3: o make CC_OPTIMIZE_FOR_DEBUGGING depends on $(cc-option,-Og) o reflect CONFIG_CC_OPTIMIZE_FOR_DEBUGGING in tiny.config --- Makefile | 5 +++++ include/linux/compiler-gcc.h | 2 +- include/linux/compiler.h | 2 +- init/Kconfig | 20 ++++++++++++++++++++ kernel/configs/tiny.config | 1 + 5 files changed, 28 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 04beb822ddfc..10de245a3325 100644 --- a/Makefile +++ b/Makefile @@ -657,6 +657,10 @@ KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) KBUILD_CFLAGS += $(call cc-disable-warning, int-in-bool-context) +ifdef CONFIG_CC_OPTIMIZE_FOR_DEBUGGING +KBUILD_CFLAGS += -Og +KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,) +else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE KBUILD_CFLAGS += $(call cc-option,-Oz,-Os) KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,) @@ -667,6 +671,7 @@ else KBUILD_CFLAGS += -O2 endif endif +endif KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \ $(call cc-disable-warning,maybe-uninitialized,)) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 90ddfefb6c2b..4832c98c7885 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -85,7 +85,7 @@ #define __compiletime_object_size(obj) __builtin_object_size(obj, 0) -#ifndef __CHECKER__ +#if !defined(__CHECKER__) && !defined(CONFIG_CC_OPTIMIZE_FOR_DEBUGGING) #define __compiletime_warning(message) __attribute__((warning(message))) #define __compiletime_error(message) __attribute__((error(message))) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 1921545c6351..3836397bf477 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -350,7 +350,7 @@ static inline void *offset_to_ptr(const int *off) * sparse see a constant array size without breaking compiletime_assert on old * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. */ -# ifndef __CHECKER__ +# if !defined(__CHECKER__) && !defined(CONFIG_CC_OPTIMIZE_FOR_DEBUGGING) # define __compiletime_error_fallback(condition) \ do { ((void)sizeof(char[1 - 2 * condition])); } while (0) # endif diff --git a/init/Kconfig b/init/Kconfig index a4112e95724a..0fb9c0b5f1a1 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1105,6 +1105,26 @@ config CC_OPTIMIZE_FOR_SIZE If unsure, say N. +config CC_OPTIMIZE_FOR_DEBUGGING + bool "Optimize for better debugging experience (-Og)" + depends on $(cc-option,-Og) + select NO_AUTO_INLINE + help + This will apply GCC '-Og' optimization level which is supported + since GCC 4.8. This optimization level offers a reasonable level + of optimization while maintaining fast compilation and a good + debugging experience. It is similar to '-O1' while preferring to + keep debug ability over runtime speed. The overall performance + will drop a bit (~6%). + + Use only if you want to debug the kernel, especially if you want + to have better kernel debugging experience with gdb facilities + like kgdb or qemu. If enabling this option breaks your kernel, + you should either disable this or find a fix (mostly in the arch + code). + + If unsure, select N. + endchoice config HAVE_LD_DEAD_CODE_DATA_ELIMINATION diff --git a/kernel/configs/tiny.config b/kernel/configs/tiny.config index 7fa0c4ae6394..599ea86b0800 100644 --- a/kernel/configs/tiny.config +++ b/kernel/configs/tiny.config @@ -1,5 +1,6 @@ # CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE is not set CONFIG_CC_OPTIMIZE_FOR_SIZE=y +# CONFIG_CC_OPTIMIZE_FOR_DEBUGGING is not set # CONFIG_KERNEL_GZIP is not set # CONFIG_KERNEL_BZIP2 is not set # CONFIG_KERNEL_LZMA is not set