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[209.132.180.67]) by mx.google.com with ESMTP id m11si4396952pgc.224.2018.04.13.09.43.37; Fri, 13 Apr 2018 09:43:51 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@google.com header.s=20161025 header.b=n3Q0JpkA; dkim=fail header.i=@chromium.org header.s=google header.b=fJucGuEp; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753206AbeDMQlx (ORCPT + 99 others); Fri, 13 Apr 2018 12:41:53 -0400 Received: from mail-ua0-f178.google.com ([209.85.217.178]:33740 "EHLO mail-ua0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753183AbeDMQlt (ORCPT ); Fri, 13 Apr 2018 12:41:49 -0400 Received: by mail-ua0-f178.google.com with SMTP id q26so6176035uab.0 for ; Fri, 13 Apr 2018 09:41:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=R5842+xAZqblF4GCQ8mSqWQmTFJxQPF0p5mJ22mWmRo=; b=n3Q0JpkAl4NauCX847VSZ8p3CJPHtVDJA2E4t5zZ2c+KrAI15SkrZQtvNOlKFiOEne lecfg+3Z/IZzkj4YGMs6DTwpQgxImFceIk1QupWaCOnB4w1SbQderlOUwB/nU0xQeNve Rdt/mKmlotxUuj+SwwXZd9NyfhjoAJ9HWiJ4f8loAPik6VjzW/uQvNXzjk+MD+GQTbvQ N6TCH9UsQc7fgs5kPAFdALuREstI0M4rIs5gPCnpqcWRcJ3kxQIZHQksPi3GmTylmufj mW7JHIVrApMsDfJA1rsxHjgk8mQPwg9Zo3N4/L5BOATougBtxJ0FxfM/9847FvALjxWD U7hQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=R5842+xAZqblF4GCQ8mSqWQmTFJxQPF0p5mJ22mWmRo=; b=fJucGuEpI0wku4NkslkNptkyOBXbfHPajw7Ed6ka8GG/8KUM2LKrF8VC/1btOmHnY+ yOpEAEahqyOwSiFSYy52YpbvawN0nVlvTQLLgZNX1JnZkD3wirLShkHGT+1H3mxfL+hn MRr0OO9Vw89B5ICOSHEJYQgYN9LtFrR2Ll3vQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=R5842+xAZqblF4GCQ8mSqWQmTFJxQPF0p5mJ22mWmRo=; b=kbY2Ovcw/saWFrba+t1WLPr6872b78JYqOvtmQCIgMTj0bAUM//J+9PBpEcx3IjTgT 4wHn5yZvy9du5uTiXNRfAh+RpLCtySIR8AYoosBAMjTOB7wml2WfsF3FsNe54nJP8QMB AdRNT601egWKeleHXN4gpUQmeMVkK5qopCKKAiwEyrFFhqQzC9IxTGw8A/sscUPB/w9E VDqnkE9gtWt2lIdsYlXX9s4/7OehhEw1Cs9Zn/iQA4FV6WkKsFd5BH2yLOlLWKH4XsGV MyTegmspmR2db7EksqbZgkxcDQm4HI8S4o79T5EpzdFsXOty+uaFjMVJ2H8dZWyia4nA 1Ulw== X-Gm-Message-State: ALQs6tB/kUy/5py615QRecRoy/xxVGAyHORN52ueu9rLYsAv9kOYm+rj hHYVNiREnu0wISFZAgtyvpsMzNQ7iqTq/3Zrn3pqaw== X-Received: by 10.176.86.206 with SMTP id c14mr4447400uab.164.1523637708652; Fri, 13 Apr 2018 09:41:48 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.164.81 with HTTP; Fri, 13 Apr 2018 09:41:48 -0700 (PDT) In-Reply-To: <1523595999-27433-22-git-send-email-yamada.masahiro@socionext.com> References: <1523595999-27433-1-git-send-email-yamada.masahiro@socionext.com> <1523595999-27433-22-git-send-email-yamada.masahiro@socionext.com> From: Kees Cook Date: Fri, 13 Apr 2018 09:41:48 -0700 X-Google-Sender-Auth: QCh7mlhHk-rlZ0hsNb74Go2mhus Message-ID: Subject: Re: [PATCH 21/30] stack-protector: test compiler capability in Kconfig and drop AUTO mode To: Masahiro Yamada Cc: linux-kbuild , Linus Torvalds , Sam Ravnborg , Ulf Magnusson , Nicholas Piggin , Emese Revfy , X86 ML , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 12, 2018 at 10:06 PM, Masahiro Yamada wrote: > +stackp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector > +stackp-flags-$(CONFIG_CC_STACKPROTECTOR) := -fstack-protector > +stackp-flags-$(CONFIG_CC_STACKPROTECTOR_STRONG) := -fstack-protector-strong > + > +KBUILD_CFLAGS += $(stackp-flags-y) So, technically, this works just fine. I wonder if it has an overly confusing result, in that the compiler under normal situations will see: gcc ... -fno-stack-protector -fstack-protector -fstack-protector-strong ... How about something like this instead: ifdef CONFIG_CC_STACKPROTECTOR_STRONG KBUILD_CFLAGS += -fstack-protector-strong else ifdef CONFIG_CC_STACKPROTECTOR KBUILD_CFLAGS += -fstack-protector else KBUILD_CFLAGS += -fno-stack-protector endif endif -Kees -- Kees Cook Pixel Security