From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Michael Neuling To: Aravinda Prasad Subject: Re: [PATCH] Enable hardware breakpoint upon re-registering In-reply-to: <20121105081527.29141.11384.stgit@aravinda> References: <20121105081527.29141.11384.stgit@aravinda> Date: Wed, 07 Nov 2012 07:53:26 +1100 Message-ID: <24260.1352235206@neuling.org> Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, fweisbec@redhat.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 >