From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754470AbZLBGcP (ORCPT ); Wed, 2 Dec 2009 01:32:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751906AbZLBGcO (ORCPT ); Wed, 2 Dec 2009 01:32:14 -0500 Received: from mail-ew0-f219.google.com ([209.85.219.219]:47266 "EHLO mail-ew0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753922AbZLBGcO (ORCPT ); Wed, 2 Dec 2009 01:32:14 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=fMZOcSWHsX7mHtJ23+uUKYiI5Ul21AE5UXkfw4HwVZsD+9jC4Icn9Ud9ifXUkSq9L1 96sNGb0nF26OF+nvJ2rfdFiMaDhOEOnhK2a7pck1acSmGV7Q8IUBKhPWYSd9QDaPZE39 1yfq1mANe9eDIYxhTaVv9aXxtbfQwQcxBaQJc= From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Frederic Weisbecker , "K.Prasad" Subject: [PATCH] hw-breakpoints: Keep track of user disabled breakpoints Date: Wed, 2 Dec 2009 07:32:16 +0100 Message-Id: <1259735536-9236-1-git-send-regression-fweisbec@gmail.com> X-Mailer: git-send-email 1.6.2.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we disable a breakpoint through dr7, we unregister it right away, making us losing track of its corresponding address register value. It means that the following sequence would be unsupported: - set address in dr0 - enable it through dr7 - disable it through dr7 - enable it through dr7 because we lost the address register value when we disabled the breakpoint. Don't unregister the disabled breakpoints but rather disable them. Reported-by: "K.Prasad" Signed-off-by: Frederic Weisbecker --- arch/x86/kernel/ptrace.c | 16 ++++++++++++---- 1 files changed, 12 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 2941b32..04d182a 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -595,7 +595,7 @@ static unsigned long ptrace_get_dr7(struct perf_event *bp[]) static struct perf_event * ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, - struct task_struct *tsk) + struct task_struct *tsk, int disabled) { int err; int gen_len, gen_type; @@ -616,7 +616,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, attr = bp->attr; attr.bp_len = gen_len; attr.bp_type = gen_type; - attr.disabled = 0; + attr.disabled = disabled; return modify_user_hw_breakpoint(bp, &attr, bp->callback, tsk); } @@ -655,13 +655,21 @@ restore: */ if (!second_pass) continue; + thread->ptrace_bps[i] = NULL; - unregister_hw_breakpoint(bp); + bp = ptrace_modify_breakpoint(bp, len, type, + tsk, 1); + if (IS_ERR(bp)) { + rc = PTR_ERR(bp); + thread->ptrace_bps[i] = NULL; + break; + } + thread->ptrace_bps[i] = bp; } continue; } - bp = ptrace_modify_breakpoint(bp, len, type, tsk); + bp = ptrace_modify_breakpoint(bp, len, type, tsk, 0); /* Incorrect bp, or we have a bug in bp API */ if (IS_ERR(bp)) { -- 1.6.2.3