| Submitter | Aravinda Prasad |
|---|---|
| Date | Nov. 5, 2012, 8:15 a.m. |
| Message ID | <20121105081527.29141.11384.stgit@aravinda> |
| Download | mbox | patch |
| Permalink | /patch/197161/ |
| State | Accepted |
| Commit | a53fd61ac2f411745471c1c877d5e072fbbf0e5c |
| Delegated to: | Benjamin Herrenschmidt |
| Headers | show |
Comments
Aravinda Prasad <aravinda@linux.vnet.ibm.com> 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 <aravinda@linux.vnet.ibm.com> Passes my tests here and I don't think it'll break existing gdb. So FWIW Acked-by: Michael Neuling <mikey@neuling.org> 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 >
Patch
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);
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 <aravinda@linux.vnet.ibm.com> --- arch/powerpc/kernel/ptrace.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)