From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8D96C5803; Fri, 1 Jul 2022 22:17:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78602C3411E; Fri, 1 Jul 2022 22:17:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1656713844; bh=qn8KeIcg6p6x70nlZj4sdymg43tnl9ycS8r/KVGYWBo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H83TOqsTu9Z06vEdS6cQCCvGtd0fvP4dXtldHjHFjMHXk01g0BVNzWlZRQrCCFYzK ABV9AmFU9GFLxfaC7rQWPgMbX6NKXYHMG6VeTR5f6W0T70V11W8EptbsABwPxt4W4g i6Wu97DhB1Db6gpS6sR6siOpcV6Qp9Vp9kinSYxRE5xMvFJcn55lQEoMy4ExOiRELX ers5txkf4Ad15PqCkiE/M33G6l07jCKank6GMPjUSVZmUeRSLOflNbh3FKsL+Tmzx7 pPD/8UMytSm1y7nErPSxTJlxv0dy3ofPLBrrrqxTMtqw0fHzWymI6aUpmRGY/VME5o aT6xl9JyjNfhg== Date: Fri, 1 Jul 2022 15:17:21 -0700 From: Nathan Chancellor To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "H. Peter Anvin" , Nick Desaulniers , Tom Rix , Daniel Kolesa , linux-kernel@vger.kernel.org, patches@lists.linux.dev, llvm@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] x86/Kconfig: Fix CONFIG_CC_HAS_SANE_STACKPROTECTOR when cross compiling with clang Message-ID: References: <20220617180845.2788442-1-nathan@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220617180845.2788442-1-nathan@kernel.org> Gentle ping for review. On Fri, Jun 17, 2022 at 11:08:46AM -0700, Nathan Chancellor wrote: > Chimera Linux notes that CONFIG_CC_HAS_SANE_STACKPROTECTOR cannot be > enabled when cross compiling an x86_64 kernel with clang, even though it > does work when natively compiling. > > When building on aarch64: > > $ make -sj"$(nproc)" ARCH=x86_64 LLVM=1 defconfig > > $ grep STACKPROTECTOR .config > > When building on x86_64: > > $ make -sj"$(nproc)" ARCH=x86_64 LLVM=1 defconfig > > $ grep STACKPROTECTOR .config > CONFIG_CC_HAS_SANE_STACKPROTECTOR=y > CONFIG_HAVE_STACKPROTECTOR=y > CONFIG_STACKPROTECTOR=y > CONFIG_STACKPROTECTOR_STRONG=y > > When clang is invoked without a '--target' flag, code is generated for > the default target, which is usually the host (it is configurable via > cmake). As a result, the has-stack-protector scripts will generate code > for the default target but check for x86 specific segment registers, > which cannot succeed if the default target is not x86. > > $(CLANG_FLAGS) contains an explicit '--target' flag so pass that > variable along to the has-stack-protector scripts so that the stack > protector can be enabled when cross compiling with clang. The 32-bit > stack protector cannot currently be enabled with clang, as it does not > support '-mstack-protector-guard-symbol', so this results in no > functional change for ARCH=i386 when cross compiling. > > Link: https://github.com/chimera-linux/cports/commit/0fb7e506d5f83fdf2104feb22cdac34934561226 > Link: https://github.com/llvm/llvm-project/issues/48553 > Signed-off-by: Nathan Chancellor > --- > > Fixes: 2a61f4747eea ("stack-protector: test compiler capability in Kconfig and drop AUTO mode") > > might be appropriate; I am conflicted on fixes tags for problems that > that arise due to use cases that were not considered at the time of a > change, as it feels wrong to blame the commit for not looking far enough > into the future where it might be common for people to have workstations > running another architecture other than x86_64. > > Chimera appears to use a 5.15 kernel so a > > Cc: stable@vger.kernel.org > > might be nice but some maintainers are picky about that so I leave it up > to you all. > > arch/x86/Kconfig | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index be0b95e51df6..076adde7ead9 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -391,8 +391,8 @@ config PGTABLE_LEVELS > > config CC_HAS_SANE_STACKPROTECTOR > bool > - default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT > - default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) > + default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT > + default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) > help > We have to make sure stack protector is unconditionally disabled if > the compiler produces broken code or if it does not let us control > > base-commit: b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 > -- > 2.36.1 > >