From patchwork Mon Feb 20 03:02:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ammar Faizi X-Patchwork-Id: 13146038 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9D37C61DA4 for ; Mon, 20 Feb 2023 03:03:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229709AbjBTDDZ (ORCPT ); Sun, 19 Feb 2023 22:03:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229572AbjBTDDY (ORCPT ); Sun, 19 Feb 2023 22:03:24 -0500 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 859369EC0; Sun, 19 Feb 2023 19:03:20 -0800 (PST) Received: from localhost.localdomain (unknown [182.253.183.169]) by gnuweeb.org (Postfix) with ESMTPSA id E2DC883127; Mon, 20 Feb 2023 03:03:12 +0000 (UTC) X-GW-Data: lPqxHiMPbJw1wb7CM9QUryAGzr0yq5atzVDdxTR0iA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1676862199; bh=GsqZ9BCgNywZeu6U972GkrKT4lGOkNYqfVTPGNRK+3g=; h=From:To:Cc:Subject:Date:From; b=P3cIv4870Q7kVt9m0xN1OoLmPXfDwsH4/KstW4RtqmRu1lwGQ/FEsubNtJRnCzNLs DJinBwmUxil3BPRdUcDi+PBVaPMQsXyTkg3gBVMSWT+2paykPEUllfHlbE7PKJv5SJ fmwCqAVD+BoAdVCHsQp4fLIzr3CHoyjcj9rK/1oXyjNxk5YUCwxQLcpl7hLcBS15aS cTTVKS1264x0mQrm4/EWEPlG8eK+bxaHWED9brMCVP78+Eqe10e9syoyVkU1gdZkdW Ljy6+XoaICOLMR5lZebEXsjbuZ5eyQeg1gbPI8JSfd5qZhmHnMTdUBgwujvdmfr+u3 7otJWWglEj5JA== From: Ammar Faizi To: Dave Hansen , Xin Li , "H. Peter Anvin" , Ingo Molnar Cc: Ammar Faizi , Andrew Cooper , Andy Lutomirski , Borislav Petkov , Thomas Gleixner , Dave Hansen , Peter Zijlstra , "Kirill A. Shutemov" , x86 Mailing List , Linux x86-64 Mailing List , Linux Kernel Mailing List , Linux Kselftest Mailing List , GNU/Weeb Mailing List Subject: [RFC PATCH v8 0/3] Intel FRED architecture support for the sysret_rip selftest Date: Mon, 20 Feb 2023 10:02:41 +0700 Message-Id: <20230220030244.115808-1-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Hi, This is an RFC v8. Based on the x86/cpu branch in the tip tree. The 'syscall' instruction on the Intel FRED architecture does not clobber %rcx and %r11. This behavior leads to an assertion failure in the sysret_rip selftest because it asserts %r11 = %rflags. In the previous discussion, we agreed that there are two cases for 'syscall': A) 'syscall' in a FRED system preserves %rcx and %r11. B) 'syscall' in a non-FRED system sets %rcx=%rip and %r11=%rflags. This series fixes the selftest. Make it work on the Intel FRED architecture. Also, add more tests to ensure the syscall behavior is consistent. It must always be (A) or always be (B). Not a mix of them. See the previous discussion here: https://lore.kernel.org/lkml/5d4ad3e3-034f-c7da-d141-9c001c2343af@intel.com ## Changelog revision v8: - Stop using "+r"(rsp) to avoid the red zone problem because it generates the wrong Assembly code (Ammar). See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108799 - Update commit message (Ammar). v7: - Fix comment, REGS_ERROR no longer exists in the enum (Ammar). - Update commit message (Ammar). v6: - Move the check-regs assertion in sigusr1() to check_regs_result() (HPA). - Add a new test just like sigusr1(), but don't modify REG_RCX and REG_R11. This is used to test SYSRET behavior consistency (HPA). v5: - Fix do_syscall() return value (Ammar). v4: - Fix the assertion condition inside the SIGUSR1 handler (Xin Li). - Explain the purpose of patch #2 in the commit message (HPA). - Update commit message (Ammar). - Repeat test_syscall_rcx_r11_consistent() 32 times to be more sure that the result is really consistent (Ammar). v3: - Test that we don't get a mix of REGS_SAVED and REGS_SYSRET, which is a major part of the point (HPA). v2: - Use "+r"(rsp) as the right way to avoid redzone problems per Andrew's comment (HPA). Co-developed-by: H. Peter Anvin (Intel) Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Ammar Faizi --- Ammar Faizi (3): selftests/x86: sysret_rip: Handle syscall on the Intel FRED architecture selftests/x86: sysret_rip: Add more tests to verify the 'syscall' behavior selftests/x86: sysret_rip: Test SYSRET with a signal handler tools/testing/selftests/x86/sysret_rip.c | 169 +++++++++++++++++++++-- 1 file changed, 160 insertions(+), 9 deletions(-) base-commit: e067248949e3de7fbeae812b0ccbbee7a401e7aa