From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760308AbZEXWgQ (ORCPT ); Sun, 24 May 2009 18:36:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758454AbZEXWf7 (ORCPT ); Sun, 24 May 2009 18:35:59 -0400 Received: from yw-out-2324.google.com ([74.125.46.30]:58358 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753973AbZEXWf6 (ORCPT ); Sun, 24 May 2009 18:35:58 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:x-x-sender:to:cc:subject:message-id:user-agent :mime-version:content-type; b=d6Wf9PwKL+C88j7wyKBjX7Aku1yHUEWehaVpB4fVcmTICDLxpFFjYOnMWCuELglb3y qAfIVQMQ/eGJSwYYGJeXVdcknIyOuc686PBvW8G9WeB+Y3mC1kTHKbuYQl8Hcl1PjSH7 L3u9V3fTmtO05AS/g49zWBvoBLFh2PwjLNwhE= Date: Sun, 24 May 2009 18:35:57 -0400 (EDT) From: Bart Oldeman X-X-Sender: bart@localhost.localdomain To: linux-kernel@vger.kernel.org cc: tglx@linutronix.de, mingo@elte.hu, stable@kernel.org Subject: [PATCH] x86, vm86: fix preemption bug for int3 breakpoint handlers. Message-ID: User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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