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/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 2d10b01..b600fc2 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -259,7 +259,7 @@
}
-int __register_perf_hw_breakpoint(struct perf_event *bp)
+int register_perf_hw_breakpoint(struct perf_event *bp)
{
int ret;
@@ -276,19 +276,12 @@
* This is a quick hack that will be removed soon, once we remove
* the tmp breakpoints from ptrace
*/
- if (!bp->attr.disabled || bp->callback == perf_bp_event)
+ if (!bp->attr.disabled || !bp->overflow_handler)
ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
return ret;
}
-int register_perf_hw_breakpoint(struct perf_event *bp)
-{
- bp->callback = perf_bp_event;
-
- return __register_perf_hw_breakpoint(bp);
-}
-
/**
* register_user_hw_breakpoint - register a hardware breakpoint for user space
* @attr: breakpoint attributes
@@ -297,7 +290,7 @@
*/
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 perf_event_create_kernel_counter(attr, -1, tsk->pid, triggered);
@@ -322,7 +315,7 @@
unregister_hw_breakpoint(bp);
return perf_event_create_kernel_counter(attr, -1, bp->ctx->task->pid,
- bp->callback);
+ bp->overflow_handler);
}
EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
@@ -347,7 +340,7 @@
*/
struct perf_event **
register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_callback_t triggered)
+ perf_overflow_handler_t triggered)
{
struct perf_event **cpu_events, **pevent, *bp;
long err;
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 6b7ddba..fd43ff4 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4286,15 +4286,8 @@
static const struct pmu *bp_perf_event_init(struct perf_event *bp)
{
int err;
- /*
- * The breakpoint is already filled if we haven't created the counter
- * through perf syscall
- * FIXME: manage to get trigerred to NULL if it comes from syscalls
- */
- if (!bp->callback)
- err = register_perf_hw_breakpoint(bp);
- else
- err = __register_perf_hw_breakpoint(bp);
+
+ err = register_perf_hw_breakpoint(bp);
if (err)
return ERR_PTR(err);
@@ -4390,7 +4383,7 @@
struct perf_event_context *ctx,
struct perf_event *group_leader,
struct perf_event *parent_event,
- perf_callback_t callback,
+ perf_overflow_handler_t overflow_handler,
gfp_t gfpflags)
{
const struct pmu *pmu;
@@ -4433,10 +4426,10 @@
event->state = PERF_EVENT_STATE_INACTIVE;
- if (!callback && parent_event)
- callback = parent_event->callback;
+ if (!overflow_handler && parent_event)
+ overflow_handler = parent_event->overflow_handler;
- event->callback = callback;
+ event->overflow_handler = overflow_handler;
if (attr->disabled)
event->state = PERF_EVENT_STATE_OFF;
@@ -4776,7 +4769,8 @@
*/
struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
- pid_t pid, perf_callback_t callback)
+ pid_t pid,
+ perf_overflow_handler_t overflow_handler)
{
struct perf_event *event;
struct perf_event_context *ctx;
@@ -4793,7 +4787,7 @@
}
event = perf_event_alloc(attr, cpu, ctx, NULL,
- NULL, callback, GFP_KERNEL);
+ NULL, overflow_handler, GFP_KERNEL);
if (IS_ERR(event)) {
err = PTR_ERR(event);
goto err_put_context;
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index ddfa0fd..acb87d4 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -79,11 +79,12 @@
}
#endif /* CONFIG_PROFILE_KSYM_TRACER */
-void ksym_hbp_handler(struct perf_event *hbp, void *data)
+void ksym_hbp_handler(struct perf_event *hbp, int nmi,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
{
struct ring_buffer_event *event;
struct ksym_trace_entry *entry;
- struct pt_regs *regs = data;
struct ring_buffer *buffer;
int pc;
