From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755861AbYCXXsF (ORCPT ); Mon, 24 Mar 2008 19:48:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753016AbYCXXrz (ORCPT ); Mon, 24 Mar 2008 19:47:55 -0400 Received: from gw.goop.org ([64.81.55.164]:53653 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752562AbYCXXry (ORCPT ); Mon, 24 Mar 2008 19:47:54 -0400 Message-ID: <47E83C99.3040800@goop.org> Date: Mon, 24 Mar 2008 16:43:21 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Ingo Molnar CC: Linux Kernel Mailing List Subject: [PATCH FIXED] x86: only enable interrupts when kernel state has been set up X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The sysenter path tries to enable interrupts immediately. Unfortunately this doesn't work in a paravirt environment, because not enough kernel state has been set up at that point (namely, pointing %fs to the kernel percpu data segment). To fix this, defer ENABLE_INTERRUPTS until after the kernel state has been set up. Unfortunately this means that we're running with interrupts disabled for a while without calling the IRQ tracing code, but that can't be called without setting up %fs either. [ Fix since last posting: make sure saved eflags has interrupts enabled. ] Signed-off-by: Jeremy Fitzhardinge --- arch/x86/kernel/entry_32.S | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) =================================================================== --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -290,10 +290,10 @@ ENTRY(ia32_sysenter_target) movl TSS_sysenter_sp0(%esp),%esp ENTRY(sysenter_past_esp) /* - * No need to follow this irqs on/off section: the syscall - * disabled irqs and here we enable it straight after entry: + * Interrupts are disabled here, but we can't trace it until + * enough kernel state to call TRACE_IRQS_OFF can be called - but + * we immediately enable interrupts at that point anyway. */ - ENABLE_INTERRUPTS(CLBR_NONE) pushl $(__USER_DS) CFI_ADJUST_CFA_OFFSET 4 /*CFI_REL_OFFSET ss, 0*/ @@ -301,6 +301,7 @@ ENTRY(sysenter_past_esp) CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET esp, 0 pushfl + orl $X86_EFLAGS_IF, (%esp) CFI_ADJUST_CFA_OFFSET 4 pushl $(__USER_CS) CFI_ADJUST_CFA_OFFSET 4 @@ -314,6 +315,11 @@ ENTRY(sysenter_past_esp) CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET eip, 0 + pushl %eax + CFI_ADJUST_CFA_OFFSET 4 + SAVE_ALL + ENABLE_INTERRUPTS(CLBR_NONE) + /* * Load the potential sixth argument from user stack. * Careful about security. @@ -321,14 +327,12 @@ ENTRY(sysenter_past_esp) cmpl $__PAGE_OFFSET-3,%ebp jae syscall_fault 1: movl (%ebp),%ebp + movl %ebp,PT_EBP(%esp) .section __ex_table,"a" .align 4 .long 1b,syscall_fault .previous - pushl %eax - CFI_ADJUST_CFA_OFFSET 4 - SAVE_ALL GET_THREAD_INFO(%ebp) /* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */ @@ -542,9 +546,6 @@ END(syscall_exit_work) RING0_INT_FRAME # can't unwind into user space anyway syscall_fault: - pushl %eax # save orig_eax - CFI_ADJUST_CFA_OFFSET 4 - SAVE_ALL GET_THREAD_INFO(%ebp) movl $-EFAULT,PT_EAX(%esp) jmp resume_userspace