From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964946AbaDIToi (ORCPT ); Wed, 9 Apr 2014 15:44:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:17239 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934320AbaDITod (ORCPT ); Wed, 9 Apr 2014 15:44:33 -0400 Date: Wed, 9 Apr 2014 21:44:31 +0200 From: Oleg Nesterov To: Ingo Molnar , Srikar Dronamraju Cc: Ananth N Mavinakayanahalli , Anton Arapov , David Long , Denys Vlasenko , "Frank Ch. Eigler" , Jim Keniston , Jonathan Lebon , Masami Hiramatsu , linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 3/6] uprobes/x86: Emulate nop's using ops->emulate() Message-ID: <20140409194431.GA6228@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140409194401.GA5854@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 Finally we can kill the ugly (and very limited) code in __skip_sstep(). Just change ttt_setup_xol_ops() to treat "nop" as jmp to the next insn. Thanks to lib/insn.c, it is clever enough. OPCODE1() == 0x90 includes "(rep;)+ nop;" at least, and (afaics) much more. Signed-off-by: Oleg Nesterov --- arch/x86/kernel/uprobes.c | 20 +------------------- 1 files changed, 1 insertions(+), 19 deletions(-) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 1cdc379..23a16a5 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -478,6 +478,7 @@ static int ttt_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) switch (OPCODE1(insn)) { case 0xeb: /* jmp 8 */ case 0xe9: /* jmp 32 */ + case 0x90: /* prefix* + nop; same as jmp with .disp = 0 */ break; default: return -ENOSYS; @@ -710,29 +711,10 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) regs->flags &= ~X86_EFLAGS_TF; } -/* - * Skip these instructions as per the currently known x86 ISA. - * rep=0x66*; nop=0x90 - */ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) { - int i; - if (auprobe->ops->emulate) return auprobe->ops->emulate(auprobe, regs); - - /* TODO: move this code into ->emulate() hook */ - for (i = 0; i < MAX_UINSN_BYTES; i++) { - if (auprobe->insn[i] == 0x66) - continue; - - if (auprobe->insn[i] == 0x90) { - regs->ip += i + 1; - return true; - } - - break; - } return false; } -- 1.5.5.1