From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752766Ab2KFUx3 (ORCPT ); Tue, 6 Nov 2012 15:53:29 -0500 Received: from ozlabs.org ([203.10.76.45]:45751 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751141Ab2KFUx1 (ORCPT ); Tue, 6 Nov 2012 15:53:27 -0500 From: Michael Neuling To: Aravinda Prasad cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, fweisbec@redhat.com, benh@kernel.crashing.org Subject: Re: [PATCH] Enable hardware breakpoint upon re-registering In-reply-to: <20121105081527.29141.11384.stgit@aravinda> References: <20121105081527.29141.11384.stgit@aravinda> Comments: In-reply-to Aravinda Prasad message dated "Mon, 05 Nov 2012 13:45:28 +0530." X-Mailer: MH-E 8.2; nmh 1.3; GNU Emacs 23.3.1 Date: Wed, 07 Nov 2012 07:53:26 +1100 Message-ID: <24260.1352235206@neuling.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Aravinda Prasad wrote: > On powerpc, ptrace will disable hardware breakpoint request once the > breakpoint is hit. It is the responsibility of the caller to set it > again. However, when the caller sets the hardware breakpoint again > using ptrace(PTRACE_SET_DEBUGREG, child_pid, 0, addr), the hardware > breakpoint is not enabled. > > While gdb's approach is to unregister and re-register the hardware > breakpoint every time the breakpoint is hit - which is working fine, > this could affect other programs trying to re-register hardware > breakpoint without unregistering. > > This patch enables hardware breakpoint if the caller is re-registering. > > Signed-off-by: Aravinda Prasad Passes my tests here and I don't think it'll break existing gdb. So FWIW Acked-by: Michael Neuling Thanks! > --- > arch/powerpc/kernel/ptrace.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c > index 79d8e56..09371d0 100644 > --- a/arch/powerpc/kernel/ptrace.c > +++ b/arch/powerpc/kernel/ptrace.c > @@ -952,6 +952,10 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, > arch_bp_generic_fields(data & > (DABR_DATA_WRITE | DABR_DATA_READ), > &attr.bp_type); > + > + /* Enable breakpoint */ > + attr.disabled = false; > + > ret = modify_user_hw_breakpoint(bp, &attr); > if (ret) { > ptrace_put_breakpoints(task); > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >