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[209.132.180.67]) by mx.google.com with ESMTP id a4si8123098pfi.226.2018.04.15.02.43.16; Sun, 15 Apr 2018 02:43:43 -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=pass header.i=@nifty.com header.s=dec2015msa header.b=kPMA62GV; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752163AbeDOJlW (ORCPT + 99 others); Sun, 15 Apr 2018 05:41:22 -0400 Received: from conssluserg-02.nifty.com ([210.131.2.81]:35523 "EHLO conssluserg-02.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751912AbeDOJlU (ORCPT ); Sun, 15 Apr 2018 05:41:20 -0400 Received: from mail-ua0-f169.google.com (mail-ua0-f169.google.com [209.85.217.169]) (authenticated) by conssluserg-02.nifty.com with ESMTP id w3F9f17T021587; Sun, 15 Apr 2018 18:41:01 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-02.nifty.com w3F9f17T021587 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1523785262; bh=uuxx970l0zwohbsBg1GMNfoCkf22BFJx9DUKdX0HD5w=; h=In-Reply-To:References:From:Date:Subject:To:Cc:From; b=kPMA62GVLnkrnvXpGByHFSsuTtDeKnxmQLF+MxzjcA1yaST/f2WJtV3edsCyH9daN T/UsQfRVll6AxUwmbxHplqZvJMeKjdhhx58quddJWyCAw+GEsGi4I7OYGtL54u01jR FXBRq8MYIikiwoze9xhUyNDhrRa+FvHYe4DGlCpP2WtkW8qiHx0mvgiRdtYxbdDiuL iq8Bt6qJK7FXEYwOrVcfBbZIfVx2oysG6YdBPNUKZ258LVjzKL/64wz4F8/kOVqzGj 1cRVxd+XiAch2PmAQLCfszcSpmYaLTvW2zDtXkh+ahAfLaomUqlM54kFBnAc17c9fx 8HuqGJ36FkC4Q== X-Nifty-SrcIP: [209.85.217.169] Received: by mail-ua0-f169.google.com with SMTP id n20so8298743ual.7; Sun, 15 Apr 2018 02:41:01 -0700 (PDT) X-Gm-Message-State: ALQs6tCd9+97Fh01ygrYHTUnt1QSk1gWIu4vNFMsydq0ITV4oZGybN0d 8morpmM4kcfowMPWJIXlR68O8KDlEX5/aQsa5+8= X-Received: by 10.159.38.8 with SMTP id 8mr8450412uag.17.1523785260530; Sun, 15 Apr 2018 02:41:00 -0700 (PDT) MIME-Version: 1.0 Received: by 10.176.85.216 with HTTP; Sun, 15 Apr 2018 02:40:20 -0700 (PDT) In-Reply-To: References: <1523595999-27433-1-git-send-email-yamada.masahiro@socionext.com> <1523595999-27433-22-git-send-email-yamada.masahiro@socionext.com> From: Masahiro Yamada Date: Sun, 15 Apr 2018 18:40:20 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 21/30] stack-protector: test compiler capability in Kconfig and drop AUTO mode To: Kees Cook 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 2018-04-14 1:41 GMT+09:00 Kees Cook : > 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 ... Kees, you are wrong. Look at my code closely. I used := operator instead of +=. $(stackp-flags-y) contains only one flag at most. > 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 > My code is much cleaner, and working fine. -- Best Regards Masahiro Yamada