4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxxxxxxx>
commit c21a493a2b44650707d06741601894329486f2ad upstream.
Currently xmon data-breakpoint feature is broken.
Whenever there is a watchpoint match occurs, hw_breakpoint_handler will
be called by do_break via notifier chains mechanism. If watchpoint is
registered by xmon, hw_breakpoint_handler won't find any associated
perf_event and returns immediately with NOTIFY_STOP. Similarly, do_break
also returns without notifying to xmon.
Solve this by returning NOTIFY_DONE when hw_breakpoint_handler does not
find any perf_event associated with matched watchpoint, rather than
NOTIFY_STOP, which tells the core code to continue calling the other
breakpoint handlers including the xmon one.
Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/hw_breakpoint.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -227,8 +227,10 @@ int __kprobes hw_breakpoint_handler(stru
rcu_read_lock();
bp = __this_cpu_read(bp_per_reg);
- if (!bp)
+ if (!bp) {
+ rc = NOTIFY_DONE;
goto out;
+ }
info = counter_arch_bp(bp);
/*