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 D6BAEC77B7F for ; Sat, 20 May 2023 13:32:56 +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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=b4DcO0P3rQgFx4ikmgL6iPyCqsk1s9IQkIreY/+6d1E=; b=aZ5F3387iRUiAC oa9d7Q9xS7P6/9iXb8AgF1jIGyR5OViCV0gJJLWMOFgfdZTOPFEDvB1kAcms6ux5BdTME218sCeZH 13lgQwTt/gjH0FgTVVl7ZVFF2wPAdt5YBDluwVqqtDdoU0SOFiQ4L1CfnMnCXN0//GrBHHWhKz9Ro vsic/+UrgJkDU+PSo8p1DfmVY7bxvNv+j28x5/hdYJeZX/qqQRW7qk7yb0vtzGqvevUzCbJV0Vllz 1cv1mkmYCLE0t48BFl+A/+xhS7ELjE/DeQesKzGZiEhW6zAvTptFI4Cxp7yiPLC+RwJpoRUYFE9PP 51xw/R/iOpGa1LAsYmGw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q0MhW-001aVt-28; Sat, 20 May 2023 13:32:50 +0000 Received: from ded1.1wt.eu ([163.172.96.212] helo=1wt.eu) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q0MhS-001aVC-1Q for linux-riscv@lists.infradead.org; Sat, 20 May 2023 13:32:48 +0000 Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 34KDWbtl027582; Sat, 20 May 2023 15:32:37 +0200 Date: Sat, 20 May 2023 15:32:37 +0200 From: Willy Tarreau To: Zhangjin Wu , linux@weissschuh.net Cc: aou@eecs.berkeley.edu, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, palmer@dabbelt.com, paul.walmsley@sifive.com, shuah@kernel.org Subject: Re: [PATCH] selftests/nolibc: Fix up compile error for rv32 Message-ID: <20230520133237.GA27501@1wt.eu> References: <20230520-nolibc-stackprotector-riscv-v1-1-d8912012a034@weissschuh.net> <20230520120254.66315-1-falcon@tinylab.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230520120254.66315-1-falcon@tinylab.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230520_063246_947304_0AED5906 X-CRM114-Status: GOOD ( 10.08 ) 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 Thomas, Zhangjin, I've merged your latest patches in my branch 20230520-nolibc-rv32+stkp2, which was rebased to integrate the updated commit messages and a few missing s-o-b from mine. Please have a look: https://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git However, Thomas, I noticed something puzzling me. While I tested with gcc-9.5 (that I have here along my toolchains) I found that it would systematically fail: sysroot/x86/include/stackprotector.h:46:1: warning: 'no_stack_protector' attribute directive ignored [-Wattributes] 46 | { | ^ !!Stack smashing detected!! qemu: uncaught target signal 6 (Aborted) - core dumped 0 test(s) passed. The reason is that it doesn't support the attribute "no_stack_protector". Upon closer investigation, I noticed that _start() on x86_64 doens't have it, yet it works on more recent compilers! So I don't understand why it works with more recent compilers. I managed to avoid the crash by enclosing the __stack_chk_init() function in a #pragma GCC optimize("-fno-stack-protector") while removing the attribute (though Clang and more recent gcc use this attribute so we shouldn't completely drop it either). I consider this non-critical as we can expect that regtests are run with a reasonably recent compiler version, but if in the long term we can find a more reliable detection for this, it would be nice. For example I found that gcc defines __SSP_ALL__ to 1 when -fstack-protector is used, and 2 when -fstack-protector-all is used. With clang, it's 1 and 3 respectively. Maybe we should use that and drop NOLIBC_STACKPROTECTOR, that would be one less variable to deal with: the code would automatically adapt to whatever cflags the user sets on the compiler, which is generally better. Regards, Willy _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv