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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 F36A2C76190 for ; Fri, 26 Jul 2019 13:53:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2B0322CEC for ; Fri, 26 Jul 2019 13:53:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564149207; bh=DPG1C/gKzo4kTxSy4m0aVqqud6lbxvx3CL1zkPkmGsg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hnzy2wSCyKbYAfb3TYUty1Gc0In6qXDDLMi0X4aXAO/l/bG0LA+gP48qPyjKJgoRA 5rOBKmLc4mALnuAjSTznK/VrQ6CrfoFY+apDpdDptkOJ5+4HMsl7viLf00kFI7h/pw jPDlWJMLmKcj0Xswt1jl+cBkyFT+lRMmvJvh83Vs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388191AbfGZNn0 (ORCPT ); Fri, 26 Jul 2019 09:43:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:51116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387697AbfGZNn0 (ORCPT ); Fri, 26 Jul 2019 09:43:26 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B318122CBD; Fri, 26 Jul 2019 13:43:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564148605; bh=DPG1C/gKzo4kTxSy4m0aVqqud6lbxvx3CL1zkPkmGsg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vxrDxzuKUu+6pS5SkcG8h4mPFtN1D2AGHFU1fM4tojdEL22XQs9esa4fPCj0S8Iq8 H6VTAg64p8i5Q8MhgQ0cJlB/oJEEvQbVCUWoESVRYddXuUbvZdsNPB6mR5v6VILvIJ HVjlp1+RbZRK8ksItxesKLOU7yw5O1jIN2/BicUQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zhenzhong Duan , Juergen Gross , Boris Ostrovsky , Stefano Stabellini , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andrew Cooper , Sasha Levin Subject: [PATCH AUTOSEL 4.19 43/47] xen/pv: Fix a boot up hang revealed by int3 self test Date: Fri, 26 Jul 2019 09:42:06 -0400 Message-Id: <20190726134210.12156-43-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190726134210.12156-1-sashal@kernel.org> References: <20190726134210.12156-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zhenzhong Duan [ Upstream commit b23e5844dfe78a80ba672793187d3f52e4b528d7 ] Commit 7457c0da024b ("x86/alternatives: Add int3_emulate_call() selftest") is used to ensure there is a gap setup in int3 exception stack which could be used for inserting call return address. This gap is missed in XEN PV int3 exception entry path, then below panic triggered: [ 0.772876] general protection fault: 0000 [#1] SMP NOPTI [ 0.772886] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0+ #11 [ 0.772893] RIP: e030:int3_magic+0x0/0x7 [ 0.772905] RSP: 3507:ffffffff82203e98 EFLAGS: 00000246 [ 0.773334] Call Trace: [ 0.773334] alternative_instructions+0x3d/0x12e [ 0.773334] check_bugs+0x7c9/0x887 [ 0.773334] ? __get_locked_pte+0x178/0x1f0 [ 0.773334] start_kernel+0x4ff/0x535 [ 0.773334] ? set_init_arg+0x55/0x55 [ 0.773334] xen_start_kernel+0x571/0x57a For 64bit PV guests, Xen's ABI enters the kernel with using SYSRET, with %rcx/%r11 on the stack. To convert back to "normal" looking exceptions, the xen thunks do 'xen_*: pop %rcx; pop %r11; jmp *'. E.g. Extracting 'xen_pv_trap xenint3' we have: xen_xenint3: pop %rcx; pop %r11; jmp xenint3 As xenint3 and int3 entry code are same except xenint3 doesn't generate a gap, we can fix it by using int3 and drop useless xenint3. Signed-off-by: Zhenzhong Duan Reviewed-by: Juergen Gross Cc: Boris Ostrovsky Cc: Juergen Gross Cc: Stefano Stabellini Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Andrew Cooper Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin --- arch/x86/entry/entry_64.S | 1 - arch/x86/include/asm/traps.h | 2 +- arch/x86/xen/enlighten_pv.c | 2 +- arch/x86/xen/xen-asm_64.S | 1 - 4 files changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 206df099950e..e7572a209fbe 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1196,7 +1196,6 @@ idtentry stack_segment do_stack_segment has_error_code=1 #ifdef CONFIG_XEN idtentry xennmi do_nmi has_error_code=0 idtentry xendebug do_debug has_error_code=0 -idtentry xenint3 do_int3 has_error_code=0 #endif idtentry general_protection do_general_protection has_error_code=1 diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index afbc87206886..b771bb3d159b 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -40,7 +40,7 @@ asmlinkage void simd_coprocessor_error(void); asmlinkage void xen_divide_error(void); asmlinkage void xen_xennmi(void); asmlinkage void xen_xendebug(void); -asmlinkage void xen_xenint3(void); +asmlinkage void xen_int3(void); asmlinkage void xen_overflow(void); asmlinkage void xen_bounds(void); asmlinkage void xen_invalid_op(void); diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 782f98b332f0..1730a26ff6ab 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -597,12 +597,12 @@ struct trap_array_entry { static struct trap_array_entry trap_array[] = { { debug, xen_xendebug, true }, - { int3, xen_xenint3, true }, { double_fault, xen_double_fault, true }, #ifdef CONFIG_X86_MCE { machine_check, xen_machine_check, true }, #endif { nmi, xen_xennmi, true }, + { int3, xen_int3, false }, { overflow, xen_overflow, false }, #ifdef CONFIG_IA32_EMULATION { entry_INT80_compat, xen_entry_INT80_compat, false }, diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index 417b339e5c8e..3a6feed76dfc 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -30,7 +30,6 @@ xen_pv_trap divide_error xen_pv_trap debug xen_pv_trap xendebug xen_pv_trap int3 -xen_pv_trap xenint3 xen_pv_trap xennmi xen_pv_trap overflow xen_pv_trap bounds -- 2.20.1