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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 71F54C6FA82 for ; Tue, 13 Sep 2022 09:44:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=u3KwyD+Wc5i/T+y38X5DTxAcSmtx5z5Ck4xRhRjyiCQ=; b=W6uZ3P2tInQaOG pAkKvLBQLkaXIRdSMQ9wfAmGjnBJ2mKX9Gs/WLwLbIi9wQo61enJzjmIhzDrYDEmSp1wnYm6WpaXB 8K/M1ETxmgK+LV3Wlr7sPW3Nrnt0Wzlc/OVrOa6zBoFnFfWN593gH+w6rDO8mpm9wZO57qwFeMkNk FQ+B9ywAttot5as/LFMEeXHqC0BM5oEit3L++ROJTvA/EVLZLoFWuNRROxKuOQcxJ1UT+v+lGPiZW sEQfKi9AfhH6ICjuISLRzfBTZGOMDYJJVNOba7BvHJzqXlWIVARwlNWLbVB108S4BU/KjVmazPc1I EO5VX8nl0mPtlNmYyTYg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oY2Sg-005Puj-H7; Tue, 13 Sep 2022 09:44:10 +0000 Received: from mail-pj1-x1035.google.com ([2607:f8b0:4864:20::1035]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oY2Sd-005Pmd-8M for linux-riscv@lists.infradead.org; Tue, 13 Sep 2022 09:44:09 +0000 Received: by mail-pj1-x1035.google.com with SMTP id s14-20020a17090a6e4e00b0020057c70943so15062519pjm.1 for ; Tue, 13 Sep 2022 02:44:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=4fh/qa6HnXSgDnhm0JxBkM8k5ZkulWvzr+Zcbwg4RXM=; b=atqATK1ZeKCXMBWbzRSUgZxYFGHp05djysHzKgikLgiiCCAE7Wy49eSm6GpiG0ddXA 02yKToQnlyT+vZx+eO0iS9WvdL0swqUwfC7jzg1MzQ2USnlHlGy4lcYAW6p1pS55e9Cz zlqfINSBE8nlQ5fpxgWmGdWtwiT5mwVRZDVmh+izffkfrZtrXPiaJ721mUbJGuH/dGyG 3tuLeZcefLniEB3fs7k25kshkrYRgkvW1n2O14FsWV6eOHmb6QHQMLggzMt7aVScisjn MNLqQUQQZENOWwVxrvJD80Pm5WygyirFTdhH/IAlT96QSquZoOYwEG5eRcVU8GmNRJiA oLow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=4fh/qa6HnXSgDnhm0JxBkM8k5ZkulWvzr+Zcbwg4RXM=; b=D0jIvNoz8RPLefWNJ9UkmptafbwUd5of0PxDtdi+AhECDdYry17jooBRubG6ffLEDu gcIKQmOCyqoufFUyDmbBG2kyP6K9jPFmmPUbFmArcHhrZ8P5ulEVM1/IEg1nEQD18P3T IB5AbLHbBkKsj0b1lUWdE6BnLgReggr8TV1aHNf/I/KpHHvhVl+1c5KgrTuGIn8OAACV LGEhHTiyj+ocZvuI1Z5EOuzr3fbFQodJkxTSyzfEI1Uq/I7kBghuYD1glIBzkTqa/hV5 3vh1uDkc3mF1P0VudJTUxYVaPWHi9xRSnyZjZr8NdXWX0fZ65A5dZ+A92ZSobHkfc6c2 pb2Q== X-Gm-Message-State: ACgBeo03CA1R9vBeDtBtk7GN/thD1k56poTD019kFpVE5Sy8/q4i+DsM MOesX5EUddj5NfeQ+MnzZyDvZw== X-Google-Smtp-Source: AA6agR7Pv3IcOLIeJnL43KewnHQIjqtc2BlvZp1mv+eRJYsZ8Q5h0RGSnQndguMeGFjCJF2Ccsp7ig== X-Received: by 2002:a17:903:2442:b0:176:c8ee:a5d6 with SMTP id l2-20020a170903244200b00176c8eea5d6mr30237049pls.20.1663062242603; Tue, 13 Sep 2022 02:44:02 -0700 (PDT) Received: from archlinux.internal.sifive.com (59-124-168-89.hinet-ip.hinet.net. [59.124.168.89]) by smtp.gmail.com with ESMTPSA id y28-20020aa79e1c000000b00543236e83e6sm4904428pfq.22.2022.09.13.02.43.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Sep 2022 02:44:02 -0700 (PDT) From: Andy Chiu To: palmer@dabbelt.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu, rostedt@goodmis.org, mingo@redhat.com, peterz@infradead.org, jpoimboe@kernel.org, jbaron@akamai.com, ardb@kernel.org Cc: greentime.hu@sifive.com, zong.li@sifive.com, andy.chiu@sifive.com, guoren@kernel.org, kernel@esmil.dk, linux-riscv@lists.infradead.org Subject: [PATCH RFC v2 riscv/for-next 1/5] riscv: align ftrace to 4 Byte boundary and increase ftrace prologue size Date: Tue, 13 Sep 2022 17:42:48 +0800 Message-Id: <20220913094252.3555240-2-andy.chiu@sifive.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220913094252.3555240-1-andy.chiu@sifive.com> References: <20220913094252.3555240-1-andy.chiu@sifive.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220913_024407_328996_FB35FC0E X-CRM114-Status: GOOD ( 11.57 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org We are introducing a new ftrace mechanism in order to phase out stop_machine() and enable kernel preemption. The new mechanism requires ftrace patchable function entries to be 24 bytes and aligned to 4 Byte boundaries. Before applying this patch, the size of the kernel code, with 122465 of ftrace entries, was at 12.46 MB. Under the same configuration, the size has increased to 12.99 MB after applying this patch set. However, we found the -falign-functions alone was not strong enoungh to make all functions align as required. In fact, cold functions are not aligned after turning on optimizations. We consider this is a bug in GCC and turn off guess-branch-probility as a workaround to align all functions. GCC bug id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345 Signed-off-by: Andy Chiu Reviewed-by: Greentime Hu --- arch/riscv/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 3fa8ef336822..fd8069f59a59 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -11,7 +11,7 @@ LDFLAGS_vmlinux := ifeq ($(CONFIG_DYNAMIC_FTRACE),y) LDFLAGS_vmlinux := --no-relax KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY - CC_FLAGS_FTRACE := -fpatchable-function-entry=8 + CC_FLAGS_FTRACE := -fpatchable-function-entry=12 -falign-functions=4 -fno-guess-branch-probability endif ifeq ($(CONFIG_CMODEL_MEDLOW),y) -- 2.36.0 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv