From patchwork Mon Nov 5 08:15:28 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Enable hardware breakpoint upon re-registering Date: Sun, 04 Nov 2012 22:15:28 -0000 From: Aravinda Prasad X-Patchwork-Id: 197161 Message-Id: <20121105081527.29141.11384.stgit@aravinda> To: linuxppc-dev@ozlabs.org, mikey@neuling.org, linux-kernel@vger.kernel.org, fweisbec@redhat.com, benh@kernel.crashing.org 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 Acked-by: Michael Neuling --- 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);