From patchwork Wed Jan 25 21:17:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ammar Faizi X-Patchwork-Id: 13116204 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 AEFD2C27C76 for ; Wed, 25 Jan 2023 21:18:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236662AbjAYVSF (ORCPT ); Wed, 25 Jan 2023 16:18:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236474AbjAYVR5 (ORCPT ); Wed, 25 Jan 2023 16:17:57 -0500 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F1D07D89; Wed, 25 Jan 2023 13:17:45 -0800 (PST) Received: from localhost.localdomain (unknown [182.253.88.152]) by gnuweeb.org (Postfix) with ESMTPSA id D6310824E0; Wed, 25 Jan 2023 21:17:38 +0000 (UTC) X-GW-Data: lPqxHiMPbJw1wb7CM9QUryAGzr0yq5atzVDdxTR0iA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1674681464; bh=vBWFR+xb4VVQ1ESzMMkJK66vUOBLYOX/iFxSXT2+DEg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RtSY8u6I6XwmtvHyIZv8YZmG7mWHsus0383CNV+Jp7r3nXQJ9z1k3IJ3IjvOk3SRe 2DDMX8YQej538IKIthIcU7BAa9m9Zken/B6McJM4LVv+/4NVrJ3QqnGWzT7D/QhrEO Ayp0zzbiy4afnTWnaBFmwvZQbBbrR30BZgcHFwrBlumRSOWFadkvoMzg/fIjlqe/Ax whBZIJ3Sf03mwZtH9bsNH19AdLqyvO9hTnjgPAzRuRwo/cYcu4U9SW/f68kjoB/UD8 xOoQanlpZwDn16uQlRXBcp6nN9r6g5wykAHsQMBB9vPj6fDs+sZSyK5K5weyLzRiH4 4Rc0EZJ3lEPMQ== From: Ammar Faizi To: "H. Peter Anvin" , Xin Li Cc: Dave Hansen , Dave Hansen , "Kirill A. Shutemov" , Thomas Gleixner , Andrew Cooper , Peter Zijlstra , Brian Gerst , Borislav Petkov , Shuah Khan , Ingo Molnar , Andy Lutomirski , x86 Mailing List , Linux Kselftest Mailing List , Linux Kernel Mailing List Subject: [RFC PATCH v6 3/3] selftests/x86: sysret_rip: Test opportunistic SYSRET Date: Thu, 26 Jan 2023 04:17:14 +0700 Message-Id: <20230125211714.838216-4-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230125211714.838216-1-ammarfaizi2@gnuweeb.org> References: <25b96960-a07e-a952-5c23-786b55054126@zytor.com> <6cd0db14-c9e2-3598-fd10-4b473d78c373@citrix.com> <5ecc383c-621b-57d9-7f6d-d63496fca3b3@zytor.com> <20230124022729.596997-1-ammarfaizi2@gnuweeb.org> <20230124022729.596997-3-ammarfaizi2@gnuweeb.org> <20230125211714.838216-1-ammarfaizi2@gnuweeb.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org When run on a non-FRED system, test the opportunistic SYSRET fast-path. Make sure the %rcx/%r11 clobbering behavior is consistent. When run on a FRED system, test that %rcx/%r11 are preserved when invoking syscall. This is similar to what test_syscall_rcx_r11_consistent() is doing, but with addition it's done via the SIGUSR2 signal handler. Link: https://lore.kernel.org/lkml/8770815f-0f23-d0c5-e56a-d401827842c9@zytor.com Suggested-by: H. Peter Anvin (Intel) Signed-off-by: Ammar Faizi --- On Wed, 25 Jan 2023 00:39:26 -0800, "H. Peter Anvin" wrote: > > /* Set IP and CX to match so that SYSRET can happen. */ > > ctx->uc_mcontext.gregs[REG_RIP] = rip; > > ctx->uc_mcontext.gregs[REG_RCX] = rip; > > It would be interesting to have the syscall handler try both with and > without this (so it would end up doing both IRET and SYSCALL on legacy.) > Perhaps SIGUSR1 versus SIGUSR2... tools/testing/selftests/x86/sysret_rip.c | 37 ++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/tools/testing/selftests/x86/sysret_rip.c b/tools/testing/selftests/x86/sysret_rip.c index d45b7f0147cd25ad..a1e5ec6f08bcd523 100644 --- a/tools/testing/selftests/x86/sysret_rip.c +++ b/tools/testing/selftests/x86/sysret_rip.c @@ -275,6 +275,28 @@ static void test_syscall_rcx_r11_consistent(void) do_syscall(__NR_getppid, 0, 0, 0, 0, 0, 0); } +static unsigned long usr2_rcx; +static unsigned long usr2_r11; + +static void sigusr2(int sig, siginfo_t *info, void *ctx_void) +{ + ucontext_t *ctx = (ucontext_t*)ctx_void; + + usr2_r11 = ctx->uc_mcontext.gregs[REG_R11]; + usr2_rcx = ctx->uc_mcontext.gregs[REG_RCX]; + + check_regs_result(ctx->uc_mcontext.gregs[REG_R11], + ctx->uc_mcontext.gregs[REG_RCX], + ctx->uc_mcontext.gregs[REG_RBX]); +} + +static void test_sysret_consistent(void) +{ + printf("[RUN]\ttest_sysret_consistent\n"); + __raise(SIGUSR2); + printf("[OK]\tRCX = %#lx; R11 = %#lx\n", usr2_rcx, usr2_r11); +} + int main() { int i; @@ -292,6 +314,21 @@ int main() for (i = 47; i < 64; i++) test_sigreturn_to(1UL<