Re: [PATCH] Enable hardware breakpoint upon re-registering
From: Michael Neuling <hidden>
Date: 2012-11-06 20:53:29
Also in:
lkml
Aravinda Prasad [off-list ref] 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 <redacted>
Passes my tests here and I don't think it'll break existing gdb. So FWIW Acked-by: Michael Neuling <redacted> Thanks!
quoted hunk ↗ jump to hunk
--- 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