From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757616AbZEWWp3 (ORCPT ); Sat, 23 May 2009 18:45:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754391AbZEWWpU (ORCPT ); Sat, 23 May 2009 18:45:20 -0400 Received: from yw-out-2324.google.com ([74.125.46.30]:28003 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752541AbZEWWpS (ORCPT ); Sat, 23 May 2009 18:45:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=to:cc:message-id:from:date; b=HMgbAbcJjYuDP0+oegtxFBPSHWsV0Gafvza4MKEid+pZGMhmVwOyPDgR8qTGGNI2M6 6mHTcy5EfVLzK4GIDhW8RV3nLM8x7WMBkEq5aZLapmwYmYN4CuyjlYniXQhZjP5QCh/X 5/52TrEneZH7CgSsSkO3M4ue7aAXbKqKarBtg= To: linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@elte.hu, stable@kernel.org Message-Id: From: Bart Oldeman Date: Sat, 23 May 2009 18:45:16 -0400 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From 090d8c2d634b456999e0928d4982ce9ea7afddf2 Mon Sep 17 00:00:00 2001 From: Bart Oldeman Date: Sat, 23 May 2009 18:16:28 -0400 Subject: [PATCH] x86, vm86: fix preemption bug for int3 breakpoint handlers. Impact: fix kernel bug such as: May 22 16:47:47 localhost kernel: note: dosemu.bin[5281] exited with preempt_count 1 Commit be716615fe596ee117292dc615e95f707fb67fd1 ("x86, vm86: fix preemption bug") fixes the problem for debug exceptions but not for breakpoints. This change also fixes breakpoints. As the offending codepath is jumping directly back to entry.S, move the logic to vm86_32.c, and re-enable preemption in vm86_handle_trap() before calling return_to_32bit(). Cc: stable@kernel.org Signed-off-by: Bart Oldeman --- arch/x86/kernel/traps.c | 4 +--- arch/x86/kernel/vm86_32.c | 6 +++++- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index f07ada4..98ebe1c 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -590,10 +590,8 @@ clear_dr7: #ifdef CONFIG_X86_32 debug_vm86: - /* reenable preemption: handle_vm86_trap() might sleep */ - dec_preempt_count(); handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1); - conditional_cli(regs); + preempt_conditional_cli(regs); return; #endif diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c index b8035a0..17c7734 100644 --- a/arch/x86/kernel/vm86_32.c +++ b/arch/x86/kernel/vm86_32.c @@ -551,8 +551,12 @@ cannot_handle: int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) { if (VMPI.is_vm86pus) { - if ((trapno == 3) || (trapno == 1)) + if ((trapno == 3) || (trapno == 1)) { + /* re-enable preemption: return_to_32bit() + jumps straight to entry_32.S */ + dec_preempt_count(); return_to_32bit(regs, VM86_TRAP + (trapno << 8)); + } do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); return 0; } -- 1.6.2.4