Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262827AbVD2QoC (ORCPT ); Fri, 29 Apr 2005 12:44:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262826AbVD2QnN (ORCPT ); Fri, 29 Apr 2005 12:43:13 -0400 Received: from fire.osdl.org ([65.172.181.4]:63670 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S262827AbVD2Qmk (ORCPT ); Fri, 29 Apr 2005 12:42:40 -0400 Date: Fri, 29 Apr 2005 09:44:28 -0700 (PDT) From: Linus Torvalds To: Roland McGrath cc: Andi Kleen , Andrew Morton , Kernel Mailing List Subject: Re: [PATCH] i386: handle iret faults better In-Reply-To: <200504290340.j3T3eCcO032218@magilla.sf.frob.com> Message-ID: References: <200504290340.j3T3eCcO032218@magilla.sf.frob.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2663 Lines: 73 On Thu, 28 Apr 2005, Roland McGrath wrote: > > I was never very happy with the special-case check for iret_exc either. > But for the first crack, I went for the fix that didn't touch other > infrastructure code. > > The fault.c changes here are really not necessary for the bug fix at all, > it will never be used there. But to make it a clean infrastructure > upgrade, I made every caller of fixup_exception consistently pass in the > complete info it uses for signals in the user-mode case. I really ended up deciding that we can fix it with a simple one-liner instead, which actually simplifies and cleans up the code, instead of adding new special cases. I just committed the appended, which actually removes one line more than it adds. Linus ----- commit a879cbbb34cbecfa9707fbb6e5a00c503ac1ecb9 tree fdf247f8dedea8f04d0989aeab6922ed073eee11 parent c06fec5022ebe014af876da2df4a0eee836e97c8 author Linus Torvalds Fri, 29 Apr 2005 09:38:44 -0700 committer Linus Torvalds Fri, 29 Apr 2005 09:38:44 -0700 x86: make traps on 'iret' be debuggable in user space This makes a trap on the 'iret' that returns us to user space cause a nice clean SIGSEGV, instead of just a hard (and silent) exit. That way a debugger can actually try to see what happened, and we also properly notify everybody who might be interested about us being gone. This loses the error code, but tells the debugger what happened with ILL_BADSTK in the siginfo. --- k/arch/i386/kernel/entry.S (mode:100644) +++ l/arch/i386/kernel/entry.S (mode:100644) @@ -260,11 +260,9 @@ restore_nocheck: .section .fixup,"ax" iret_exc: sti - movl $__USER_DS, %edx - movl %edx, %ds - movl %edx, %es - movl $11,%eax - call do_exit + pushl $0 # no error code + pushl $do_iret_error + jmp error_code .previous .section __ex_table,"a" .align 4 --- k/arch/i386/kernel/traps.c (mode:100644) +++ l/arch/i386/kernel/traps.c (mode:100644) @@ -451,6 +451,7 @@ DO_ERROR(10, SIGSEGV, "invalid TSS", inv DO_ERROR(11, SIGBUS, "segment not present", segment_not_present) DO_ERROR(12, SIGBUS, "stack segment", stack_segment) DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0) +DO_ERROR_INFO(32, SIGSEGV, "iret exception", iret_error, ILL_BADSTK, 0) fastcall void do_general_protection(struct pt_regs * regs, long error_code) { - 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/