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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34043C11F6F for ; Sat, 10 Jul 2021 23:52:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CA0061411 for ; Sat, 10 Jul 2021 23:52:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233819AbhGJXyq (ORCPT ); Sat, 10 Jul 2021 19:54:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:41452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233298AbhGJXx2 (ORCPT ); Sat, 10 Jul 2021 19:53:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 53F63613DA; Sat, 10 Jul 2021 23:50:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625961042; bh=iM1K6mqKlaFRjb/3+kOuMfyvud8VMFcfwJgch6Mi2cM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bPVoZ9vzsXxKCQVDTkofdGqLq/GBPHu4VgpkuJXBOQbQNXtbAgeRIbVWW8cjTOyqB MQK2YXi5ffi6QakcstSudQMxP/S1SMtQ0eXEu4QSw4CQ9YYNS7Chmn4+oz3GLKrGWi V6sScEHEUOXMc71YNmjyyOjgl3joQfChfl/oC5TbFcj4O/qnHoLb41wvGtNh9JLpvo 6+GIE4qZF9PcBgw7IfBukbW9xQqs2xs44NcynyfuDdoqs/zku5OW7JFoQhR1Vd6XYn feWwApErR3SgchDqD6vP2K3Do+t0AHDfYTjOVZVpe6hV3mh0JATLcSu0vojRw6AYiS ZR6XMp7dYtVng== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Thomas Gleixner , Borislav Petkov , Sasha Levin Subject: [PATCH AUTOSEL 5.10 19/37] x86/fpu: Return proper error codes from user access functions Date: Sat, 10 Jul 2021 19:49:57 -0400 Message-Id: <20210710235016.3221124-19-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210710235016.3221124-1-sashal@kernel.org> References: <20210710235016.3221124-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner [ Upstream commit aee8c67a4faa40a8df4e79316dbfc92d123989c1 ] When *RSTOR from user memory raises an exception, there is no way to differentiate them. That's bad because it forces the slow path even when the failure was not a fault. If the operation raised eg. #GP then going through the slow path is pointless. Use _ASM_EXTABLE_FAULT() which stores the trap number and let the exception fixup return the negated trap number as error. This allows to separate the fast path and let it handle faults directly and avoid the slow path for all other exceptions. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121457.601480369@linutronix.de Signed-off-by: Sasha Levin --- arch/x86/include/asm/fpu/internal.h | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 16bf4d4a8159..4e5af2b00d89 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -103,6 +103,7 @@ static inline void fpstate_init_fxstate(struct fxregs_state *fx) } extern void fpstate_sanitize_xstate(struct fpu *fpu); +/* Returns 0 or the negated trap number, which results in -EFAULT for #PF */ #define user_insn(insn, output, input...) \ ({ \ int err; \ @@ -110,14 +111,14 @@ extern void fpstate_sanitize_xstate(struct fpu *fpu); might_fault(); \ \ asm volatile(ASM_STAC "\n" \ - "1:" #insn "\n\t" \ + "1: " #insn "\n" \ "2: " ASM_CLAC "\n" \ ".section .fixup,\"ax\"\n" \ - "3: movl $-1,%[err]\n" \ + "3: negl %%eax\n" \ " jmp 2b\n" \ ".previous\n" \ - _ASM_EXTABLE(1b, 3b) \ - : [err] "=r" (err), output \ + _ASM_EXTABLE_FAULT(1b, 3b) \ + : [err] "=a" (err), output \ : "0"(0), input); \ err; \ }) @@ -219,16 +220,20 @@ static inline void fxsave(struct fxregs_state *fx) #define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" #define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" +/* + * After this @err contains 0 on success or the negated trap number when + * the operation raises an exception. For faults this results in -EFAULT. + */ #define XSTATE_OP(op, st, lmask, hmask, err) \ asm volatile("1:" op "\n\t" \ "xor %[err], %[err]\n" \ "2:\n\t" \ ".pushsection .fixup,\"ax\"\n\t" \ - "3: movl $-2,%[err]\n\t" \ + "3: negl %%eax\n\t" \ "jmp 2b\n\t" \ ".popsection\n\t" \ - _ASM_EXTABLE(1b, 3b) \ - : [err] "=r" (err) \ + _ASM_EXTABLE_FAULT(1b, 3b) \ + : [err] "=a" (err) \ : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ : "memory") -- 2.30.2