Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261752AbVDAIg2 (ORCPT ); Fri, 1 Apr 2005 03:36:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261750AbVDAIg2 (ORCPT ); Fri, 1 Apr 2005 03:36:28 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.146]:4503 "EHLO e6.ny.us.ibm.com") by vger.kernel.org with ESMTP id S261752AbVDAIgD (ORCPT ); Fri, 1 Apr 2005 03:36:03 -0500 Date: Fri, 1 Apr 2005 14:07:10 +0530 From: Prasanna S Panchamukhi To: SystemTAP , akpm@osdl.org, Andi Kleen , davem@davemloft.net, ananth@in.ibm.com, linux-kernel@vger.kernel.org Subject: [PATCH] Kprobes: Incorrect handling of probes on ret/lret instruction Message-ID: <20050401083710.GA1681@in.ibm.com> Reply-To: prasanna@in.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2431 Lines: 71 Hi, Kprobes could not handle the insertion of a probe on the ret/lret instruction and used to oops after single stepping since kprobes was modifying eip/rip incorrectly. Adjustment of eip/rip is not required after single stepping in case of ret/lret instruction, because eip/rip points to the correct location after execution of the ret/lret instruction. This patch fixes the above problem. Signed-off-by: Prasanna S Panchamukhi --- --- linux-2.6.12-rc1-prasanna/arch/i386/kernel/kprobes.c | 7 +++++++ linux-2.6.12-rc1-prasanna/arch/x86_64/kernel/kprobes.c | 7 +++++++ 2 files changed, 14 insertions(+) diff -puN arch/i386/kernel/kprobes.c~kprobes-ret-address-fix arch/i386/kernel/kprobes.c --- linux-2.6.12-rc1/arch/i386/kernel/kprobes.c~kprobes-ret-address-fix 2005-03-31 14:32:56.000000000 +0530 +++ linux-2.6.12-rc1-prasanna/arch/i386/kernel/kprobes.c 2005-03-31 14:37:24.000000000 +0530 @@ -218,6 +218,13 @@ static void resume_execution(struct kpro *tos &= ~(TF_MASK | IF_MASK); *tos |= kprobe_old_eflags; break; + case 0xc3: /* ret/lret */ + case 0xcb: + case 0xc2: + case 0xca: + regs->eflags &= ~TF_MASK; + /* eip is already adjusted, no more changes required*/ + return; case 0xe8: /* call relative - Fix return addr */ *tos = orig_eip + (*tos - copy_eip); break; diff -puN arch/x86_64/kernel/kprobes.c~kprobes-ret-address-fix arch/x86_64/kernel/kprobes.c --- linux-2.6.12-rc1/arch/x86_64/kernel/kprobes.c~kprobes-ret-address-fix 2005-03-31 14:33:31.000000000 +0530 +++ linux-2.6.12-rc1-prasanna/arch/x86_64/kernel/kprobes.c 2005-03-31 14:37:08.000000000 +0530 @@ -231,6 +231,13 @@ static void resume_execution(struct kpro *tos &= ~(TF_MASK | IF_MASK); *tos |= kprobe_old_rflags; break; + case 0xc3: /* ret/lret */ + case 0xcb: + case 0xc2: + case 0xca: + regs->eflags &= ~TF_MASK; + /* rip is already adjusted, no more changes required*/ + return; case 0xe8: /* call relative - Fix return addr */ *tos = orig_rip + (*tos - copy_rip); break; _ Thanks Prasanna -- Prasanna S Panchamukhi Linux Technology Center India Software Labs, IBM Bangalore Ph: 91-80-25044636 - 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/