path: root/arch
diff options
authorJason Wessel <jason.wessel@windriver.com>2010-07-28 19:10:30 -0500
committerJason Wessel <jason.wessel@windriver.com>2010-07-28 19:10:30 -0500
commitba773f7c510c0b252145933926c636c439889207 (patch)
tree97983dc7a149487a7926f1efc2619fafcc8cc93c /arch
parentfc0f5ac8fe693d1b05f5a928cc48135d1c8b7f2e (diff)
x86,kgdb: Fix hw breakpoint regression
HW breakpoints events stopped working correctly with kgdb as a result of commit: 018cbffe6819f6f8db20a0a3acd9bab9bfd667e4 (Merge commit 'v2.6.33' into perf/core). The regression occurred because the behavior changed for setting NOTIFY_STOP as the return value to the die notifier if the breakpoint was known to the HW breakpoint API. Because kgdb is using the HW breakpoint API to register HW breakpoints slots, it must also now implement the overflow_handler call back else kgdb does not get to see the events from the die notifier. The kgdb_ll_trap function will be changed to be general purpose code which can allow an easy way to implement the hw_breakpoint API overflow call back. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Acked-by: Dongdong Deng <dongdong.deng@windriver.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'arch')
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 4f4af75b948..01ab17ae2ae 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -572,7 +572,6 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
int kgdb_ll_trap(int cmd, const char *str,
struct pt_regs *regs, long err, int trap, int sig)
@@ -590,7 +589,6 @@ int kgdb_ll_trap(int cmd, const char *str,
return __kgdb_notify(&args, cmd);
static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
@@ -625,6 +623,12 @@ int kgdb_arch_init(void)
return register_die_notifier(&kgdb_notifier);
+static void kgdb_hw_overflow_handler(struct perf_event *event, int nmi,
+ struct perf_sample_data *data, struct pt_regs *regs)
+ kgdb_ll_trap(DIE_DEBUG, "debug", regs, 0, 0, SIGTRAP);
void kgdb_arch_late(void)
int i, cpu;
@@ -655,6 +659,7 @@ void kgdb_arch_late(void)
for_each_online_cpu(cpu) {
pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
pevent[0]->hw.sample_period = 1;
+ pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
if (pevent[0]->destroy != NULL) {
pevent[0]->destroy = NULL;