hw-breakpoints: Use overflow handler instead of the event callback
struct perf_event::event callback was called when a breakpoint
triggers. But this is a rather opaque callback, pretty
tied-only to the breakpoint API and not really integrated into perf
as it triggers even when we don't overflow.
We prefer to use overflow_handler() as it fits into the perf events
rules, being called only when we overflow.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index d33096e..4d14a38 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -20,19 +20,16 @@
#ifdef CONFIG_HAVE_HW_BREAKPOINT
-/* As it's for in-kernel or ptrace use, we want it to be pinned */
-#define DEFINE_BREAKPOINT_ATTR(name) \
-struct perf_event_attr name = { \
- .type = PERF_TYPE_BREAKPOINT, \
- .size = sizeof(name), \
- .pinned = 1, \
-};
-
static inline void hw_breakpoint_init(struct perf_event_attr *attr)
{
attr->type = PERF_TYPE_BREAKPOINT;
attr->size = sizeof(*attr);
+ /*
+ * As it's for in-kernel or ptrace use, we want it to be pinned
+ * and to call its callback every hits.
+ */
attr->pinned = 1;
+ attr->sample_period = 1;
}
static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
@@ -52,7 +49,7 @@
extern struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr,
- perf_callback_t triggered,
+ perf_overflow_handler_t triggered,
struct task_struct *tsk);
/* FIXME: only change from the attr, and don't unregister */
@@ -64,12 +61,12 @@
*/
extern struct perf_event *
register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
- perf_callback_t triggered,
+ perf_overflow_handler_t triggered,
int cpu);
extern struct perf_event **
register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_callback_t triggered);
+ perf_overflow_handler_t triggered);
extern int register_perf_hw_breakpoint(struct perf_event *bp);
extern int __register_perf_hw_breakpoint(struct perf_event *bp);
@@ -90,18 +87,18 @@
static inline struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr,
- perf_callback_t triggered,
+ perf_overflow_handler_t triggered,
struct task_struct *tsk) { return NULL; }
static inline struct perf_event *
modify_user_hw_breakpoint(struct perf_event *bp,
struct perf_event_attr *attr) { return NULL; }
static inline struct perf_event *
register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
- perf_callback_t triggered,
+ perf_overflow_handler_t triggered,
int cpu) { return NULL; }
static inline struct perf_event **
register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_callback_t triggered) { return NULL; }
+ perf_overflow_handler_t triggered) { return NULL; }
static inline int
register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
static inline int
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 84bd28a..d2f2667 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -565,10 +565,13 @@
void (*func)(struct perf_pending_entry *);
};
-typedef void (*perf_callback_t)(struct perf_event *, void *);
-
struct perf_sample_data;
+typedef void (*perf_callback_t)(struct perf_event *, void *);
+typedef void (*perf_overflow_handler_t)(struct perf_event *, int,
+ struct perf_sample_data *,
+ struct pt_regs *regs);
+
/**
* struct perf_event - performance event kernel representation:
*/
@@ -660,9 +663,7 @@
struct pid_namespace *ns;
u64 id;
- void (*overflow_handler)(struct perf_event *event,
- int nmi, struct perf_sample_data *data,
- struct pt_regs *regs);
+ perf_overflow_handler_t overflow_handler;
#ifdef CONFIG_EVENT_PROFILE
struct event_filter *filter;
@@ -779,7 +780,7 @@
perf_event_create_kernel_counter(struct perf_event_attr *attr,
int cpu,
pid_t pid,
- perf_callback_t callback);
+ perf_overflow_handler_t callback);
extern u64 perf_event_read_value(struct perf_event *event,
u64 *enabled, u64 *running);