From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751649Ab2I3TlR (ORCPT ); Sun, 30 Sep 2012 15:41:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1397 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751518Ab2I3Tkk (ORCPT ); Sun, 30 Sep 2012 15:40:40 -0400 Date: Sun, 30 Sep 2012 21:41:58 +0200 From: Oleg Nesterov To: Ingo Molnar , Peter Zijlstra , Srikar Dronamraju Cc: Ananth N Mavinakayanahalli , Anton Arapov , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org Subject: [PATCH 1/7] uprobes/x86: Only rep+nop can be emulated correctly Message-ID: <20120930194158.GA11316@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120930194119.GA11278@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org __skip_sstep() correctly detects the "nontrivial" nop insns, but since it doesn't update regs->ip we can not really skip "0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0", the probed application is killed by SIGILL'ed handle_swbp(). Remove these additional checks. If we want to implement this correctly we need to know the full insn length to update ->ip. rep* + nop is fine even without updating ->ip. Signed-off-by: Oleg Nesterov --- arch/x86/kernel/uprobes.c | 16 ++-------------- 1 files changed, 2 insertions(+), 14 deletions(-) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 9538f00..aafa555 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -651,31 +651,19 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) /* * Skip these instructions as per the currently known x86 ISA. - * 0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 } + * rep=0x66*; nop=0x90 */ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) { int i; for (i = 0; i < MAX_UINSN_BYTES; i++) { - if ((auprobe->insn[i] == 0x66)) + if (auprobe->insn[i] == 0x66) continue; if (auprobe->insn[i] == 0x90) return true; - if (i == (MAX_UINSN_BYTES - 1)) - break; - - if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x1f)) - return true; - - if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x19)) - return true; - - if ((auprobe->insn[i] == 0x87) && (auprobe->insn[i+1] == 0xc0)) - return true; - break; } return false; -- 1.5.5.1