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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F24EC433F5 for ; Wed, 8 Dec 2021 11:14:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232358AbhLHLRa (ORCPT ); Wed, 8 Dec 2021 06:17:30 -0500 Received: from mail.skyhub.de ([5.9.137.197]:60840 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232254AbhLHLRV (ORCPT ); Wed, 8 Dec 2021 06:17:21 -0500 Received: from zn.tnic (dslb-088-067-202-008.088.067.pools.vodafone-ip.de [88.67.202.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id D80291EC0559; Wed, 8 Dec 2021 12:13:48 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1638962029; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=m0fA2FuhL0QWaK7kuRMWQqHpKm40WGm8JUqeDMAE2X0=; b=mSEVJF1FMBZS8C9PLycX7mhI/D4aWXtt9Fbk3uuLMgCxmXam/vCUob3l4tIBr8Vpbilk2g NgZCAetIG4pKXU1pGHowDP5ZGpBZ45i9taQrFyipH0GMKwocBqhAlsUol1HDcxQ6flEckF 92M8RzyIP+ZxrwETC28oPKxWexDVVUI= From: Borislav Petkov To: Tony Luck Cc: X86 ML , LKML Subject: [PATCH v1 06/12] x86/mce: Prevent severity computation from being instrumented Date: Wed, 8 Dec 2021 12:13:37 +0100 Message-Id: <20211208111343.8130-7-bp@alien8.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20211208111343.8130-1-bp@alien8.de> References: <20211208111343.8130-1-bp@alien8.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Borislav Petkov Mark all the MCE severity computation logic noinstr and allow instrumentation when it "calls out". Fixes vmlinux.o: warning: objtool: do_machine_check()+0xc5d: call to mce_severity() leaves .noinstr.text section Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/mce/severity.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c index 00e97ebbd94a..a32646769705 100644 --- a/arch/x86/kernel/cpu/mce/severity.c +++ b/arch/x86/kernel/cpu/mce/severity.c @@ -263,24 +263,36 @@ static bool is_copy_from_user(struct pt_regs *regs) * distinguish an exception taken in user from from one * taken in the kernel. */ -static int error_context(struct mce *m, struct pt_regs *regs) +static noinstr int error_context(struct mce *m, struct pt_regs *regs) { + int fixup_type; + bool copy_user; + if ((m->cs & 3) == 3) return IN_USER; + if (!mc_recoverable(m->mcgstatus)) return IN_KERNEL; - switch (ex_get_fixup_type(m->ip)) { + /* Allow instrumentation around external facilities usage. */ + instrumentation_begin(); + fixup_type = ex_get_fixup_type(m->ip); + copy_user = is_copy_from_user(regs); + instrumentation_end(); + + switch (fixup_type) { case EX_TYPE_UACCESS: case EX_TYPE_COPY: - if (!regs || !is_copy_from_user(regs)) + if (!regs || !copy_user) return IN_KERNEL; m->kflags |= MCE_IN_KERNEL_COPYIN; fallthrough; + case EX_TYPE_FAULT_MCE_SAFE: case EX_TYPE_DEFAULT_MCE_SAFE: m->kflags |= MCE_IN_KERNEL_RECOV; return IN_KERNEL_RECOV; + default: return IN_KERNEL; } @@ -315,8 +327,8 @@ static int mce_severity_amd_smca(struct mce *m, enum context err_ctx) * See AMD Error Scope Hierarchy table in a newer BKDG. For example * 49125_15h_Models_30h-3Fh_BKDG.pdf, section "RAS Features" */ -static int mce_severity_amd(struct mce *m, struct pt_regs *regs, int tolerant, - char **msg, bool is_excp) +static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, int tolerant, + char **msg, bool is_excp) { enum context ctx = error_context(m, regs); @@ -368,8 +380,8 @@ static int mce_severity_amd(struct mce *m, struct pt_regs *regs, int tolerant, return MCE_KEEP_SEVERITY; } -static int mce_severity_intel(struct mce *m, struct pt_regs *regs, - int tolerant, char **msg, bool is_excp) +static noinstr int mce_severity_intel(struct mce *m, struct pt_regs *regs, + int tolerant, char **msg, bool is_excp) { enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP); enum context ctx = error_context(m, regs); @@ -405,8 +417,8 @@ static int mce_severity_intel(struct mce *m, struct pt_regs *regs, } } -int mce_severity(struct mce *m, struct pt_regs *regs, int tolerant, char **msg, - bool is_excp) +int noinstr mce_severity(struct mce *m, struct pt_regs *regs, int tolerant, char **msg, + bool is_excp) { if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) -- 2.29.2