From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754032AbdKXRc0 (ORCPT ); Fri, 24 Nov 2017 12:32:26 -0500 Received: from mail-wr0-f194.google.com ([209.85.128.194]:35433 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753820AbdKXRY6 (ORCPT ); Fri, 24 Nov 2017 12:24:58 -0500 X-Google-Smtp-Source: AGs4zMZPeTjDYj+8nni7+RuHInrw5iOITYECRoVvlenG533QRZ1kN9on5BybOenoVOaciQZS3WyxjA== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Dave Hansen , Andy Lutomirski , Thomas Gleixner , "H . Peter Anvin" , Peter Zijlstra , Borislav Petkov , Linus Torvalds Subject: [PATCH 12/43] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Date: Fri, 24 Nov 2017 18:23:40 +0100 Message-Id: <20171124172411.19476-13-mingo@kernel.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171124172411.19476-1-mingo@kernel.org> References: <20171124172411.19476-1-mingo@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski When we start using an entry trampoline, a #GP from userspace will be delivered on the entry stack, not on the task stack. Fix the espfix64 #DF fixup to set up #GP according to TSS.SP0, rather than assuming that pt_regs + 1 == SP0. This won't change anything without an entry stack, but it will make the code continue to work when an entry stack is added. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Link: https://lkml.kernel.org/r/b1ef4136616c6bd2a75d1fd2736d1d54437d65a8.1511497875.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 2008dd0f8ccb..1bd43f044c62 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -359,7 +359,8 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) regs->cs == __KERNEL_CS && regs->ip == (unsigned long)native_irq_return_iret) { - struct pt_regs *normal_regs = task_pt_regs(current); + struct pt_regs *normal_regs = + (struct pt_regs *)this_cpu_read(cpu_tss.x86_tss.sp0) - 1; /* Fake a #GP(0) from userspace. */ memmove(&normal_regs->ip, (void *)regs->sp, 5*8); @@ -390,7 +391,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) * * Processors update CR2 whenever a page fault is detected. If a * second page fault occurs while an earlier page fault is being - * deliv- ered, the faulting linear address of the second fault will + * delivered, the faulting linear address of the second fault will * overwrite the contents of CR2 (replacing the previous * address). These updates to CR2 occur even if the page fault * results in a double fault or occurs during the delivery of a -- 2.14.1