Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965639Ab2EOC1m (ORCPT ); Mon, 14 May 2012 22:27:42 -0400 Received: from mail.windriver.com ([147.11.1.11]:49871 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965516Ab2EOCSR (ORCPT ); Mon, 14 May 2012 22:18:17 -0400 From: Paul Gortmaker To: , Subject: [34-longterm 168/179] x86-32, vdso: On system call restart after SYSENTER, use int $0x80 Date: Mon, 14 May 2012 22:14:24 -0400 Message-ID: <1337048075-6132-169-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.9.6 In-Reply-To: <1337048075-6132-1-git-send-email-paul.gortmaker@windriver.com> References: <1337048075-6132-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1996 Lines: 49 From: "H. Peter Anvin" ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit 7ca0758cdb7c241cb4e0490a8d95f0eb5b861daf upstream. When we enter a 32-bit system call via SYSENTER or SYSCALL, we shuffle the arguments to match the int $0x80 calling convention. This was probably a design mistake, but it's what it is now. This causes errors if the system call as to be restarted. For SYSENTER, we have to invoke the instruction from the vdso as the return address is hardcoded. Accordingly, we can simply replace the jump in the vdso with an int $0x80 instruction and use the slower entry point for a post-restart. Suggested-by: Linus Torvalds Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/CA%2B55aFztZ=r5wa0x26KJQxvZOaQq8s2v3u50wCyJcA-Sc4g8gQ@mail.gmail.com Signed-off-by: Paul Gortmaker --- arch/x86/vdso/vdso32/sysenter.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/vdso/vdso32/sysenter.S b/arch/x86/vdso/vdso32/sysenter.S index e2800af..e354bce 100644 --- a/arch/x86/vdso/vdso32/sysenter.S +++ b/arch/x86/vdso/vdso32/sysenter.S @@ -43,7 +43,7 @@ __kernel_vsyscall: .space 7,0x90 /* 14: System call restart point is here! (SYSENTER_RETURN-2) */ - jmp .Lenter_kernel + int $0x80 /* 16: System call normal return point is here! */ VDSO32_SYSENTER_RETURN: /* Symbol used by sysenter.c via vdso32-syms.h */ pop %ebp -- 1.7.9.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/