From nobody Mon Sep 29 21:26:49 2025 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 4CEAAC00140 for ; Mon, 15 Aug 2022 23:10:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347825AbiHOXK1 (ORCPT ); Mon, 15 Aug 2022 19:10:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345372AbiHOXIm (ORCPT ); Mon, 15 Aug 2022 19:08:42 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0C067968D; Mon, 15 Aug 2022 12:59:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8691361295; Mon, 15 Aug 2022 19:59:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE2D2C433C1; Mon, 15 Aug 2022 19:59:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660593585; bh=eUGW2Is/pHYPEz+f+EhA8vgHM3cR2Z6ILuc72rM9470=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HTr3f/4Pnw+7YMYztJH1ALdv0oOlfc1zb7q4+bpbfo2xolDwxr9c9lfGd7yNj7Xi1 5g5sG9eKTG26Tc2hDIWLMiOgWT/dIE76hkFDIvdn406rxiNclW57nk3QdoW8eCQBU0 oBw73nfp/mRtuF2jVgkKqFv3UzBdhSREqiQj2U3w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephane Eranian , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 5.19 0292/1157] x86/extable: Fix ex_handler_msr() print condition Date: Mon, 15 Aug 2022 19:54:08 +0200 Message-Id: <20220815180451.301170690@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180439.416659447@linuxfoundation.org> References: <20220815180439.416659447@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Peter Zijlstra [ Upstream commit a1a5482a2c6e38a3ebed32e571625c56a8cc41a6 ] On Fri, Jun 17, 2022 at 02:08:52PM +0300, Stephane Eranian wrote: > Some changes to the way invalid MSR accesses are reported by the > kernel is causing some problems with messages printed on the > console. > > We have seen several cases of ex_handler_msr() printing invalid MSR > accesses once but the callstack multiple times causing confusion on > the console. > The problem here is that another earlier commit (5.13): > > a358f40600b3 ("once: implement DO_ONCE_LITE for non-fast-path "do once" f= unctionality") > > Modifies all the pr_*_once() calls to always return true claiming > that no caller is ever checking the return value of the functions. > > This is why we are seeing the callstack printed without the > associated printk() msg. Extract the ONCE_IF(cond) part into __ONCE_LTE_IF() and use that to implement DO_ONCE_LITE_IF() and fix the extable code. Fixes: a358f40600b3 ("once: implement DO_ONCE_LITE for non-fast-path "do on= ce" functionality") Reported-by: Stephane Eranian Signed-off-by: Peter Zijlstra (Intel) Tested-by: Stephane Eranian Link: https://lkml.kernel.org/r/YqyVFsbviKjVGGZ9@worktop.programming.kicks-= ass.net Signed-off-by: Sasha Levin --- arch/x86/mm/extable.c | 16 +++++++++------- include/linux/once_lite.h | 20 ++++++++++++++++---- 2 files changed, 25 insertions(+), 11 deletions(-) diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index dba2197c05c3..331310c29349 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -94,16 +94,18 @@ static bool ex_handler_copy(const struct exception_tabl= e_entry *fixup, static bool ex_handler_msr(const struct exception_table_entry *fixup, struct pt_regs *regs, bool wrmsr, bool safe, int reg) { - if (!safe && wrmsr && - pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to wri= te 0x%08x%08x) at rIP: 0x%lx (%pS)\n", - (unsigned int)regs->cx, (unsigned int)regs->dx, - (unsigned int)regs->ax, regs->ip, (void *)regs->ip)) + if (__ONCE_LITE_IF(!safe && wrmsr)) { + pr_warn("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08= x%08x) at rIP: 0x%lx (%pS)\n", + (unsigned int)regs->cx, (unsigned int)regs->dx, + (unsigned int)regs->ax, regs->ip, (void *)regs->ip); show_stack_regs(regs); + } =20 - if (!safe && !wrmsr && - pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%= lx (%pS)\n", - (unsigned int)regs->cx, regs->ip, (void *)regs->ip)) + if (__ONCE_LITE_IF(!safe && !wrmsr)) { + pr_warn("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)= \n", + (unsigned int)regs->cx, regs->ip, (void *)regs->ip); show_stack_regs(regs); + } =20 if (!wrmsr) { /* Pretend that the read succeeded and returned 0. */ diff --git a/include/linux/once_lite.h b/include/linux/once_lite.h index 861e606b820f..b7bce4983638 100644 --- a/include/linux/once_lite.h +++ b/include/linux/once_lite.h @@ -9,15 +9,27 @@ */ #define DO_ONCE_LITE(func, ...) \ DO_ONCE_LITE_IF(true, func, ##__VA_ARGS__) -#define DO_ONCE_LITE_IF(condition, func, ...) \ + +#define __ONCE_LITE_IF(condition) \ ({ \ static bool __section(".data.once") __already_done; \ - bool __ret_do_once =3D !!(condition); \ + bool __ret_cond =3D !!(condition); \ + bool __ret_once =3D false; \ \ - if (unlikely(__ret_do_once && !__already_done)) { \ + if (unlikely(__ret_cond && !__already_done)) { \ __already_done =3D true; \ - func(__VA_ARGS__); \ + __ret_once =3D true; \ } \ + unlikely(__ret_once); \ + }) + +#define DO_ONCE_LITE_IF(condition, func, ...) \ + ({ \ + bool __ret_do_once =3D !!(condition); \ + \ + if (__ONCE_LITE_IF(__ret_do_once)) \ + func(__VA_ARGS__); \ + \ unlikely(__ret_do_once); \ }) =20 --=20 2.35.1