static void bts_event_start(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
struct bts_buffer *buf;
buf = perf_aux_output_begin(&bts->handle, event);
if (!buf)
goto fail_stop;
if (bts_buffer_reset(buf, &bts->handle))
goto fail_end_stop;
bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base;
bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum;
bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold;
event->hw.itrace_started = 1;
event->hw.state = 0;
__bts_event_start(event);
return;
fail_end_stop:
perf_aux_output_end(&bts->handle, 0, false);
fail_stop:
event->hw.state = PERF_HES_STOPPED;
}
static int bts_event_add(struct perf_event *event, int mode)
{
struct bts_buffer *buf;
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct hw_perf_event *hwc = &event->hw;
int ret = -EBUSY;
event->hw.state = PERF_HES_STOPPED;
if (test_bit(INTEL_PMC_IDX_FIXED_BTS, cpuc->active_mask))
return -EBUSY;
if (bts->handle.event)
return -EBUSY;
buf = perf_aux_output_begin(&bts->handle, event);
if (!buf)
return -EINVAL;
ret = bts_buffer_reset(buf, &bts->handle);
if (ret) {
perf_aux_output_end(&bts->handle, 0, false);
return ret;
}
bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base;
bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum;
bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold;
if (mode & PERF_EF_START) {
bts_event_start(event, 0);
if (hwc->state & PERF_HES_STOPPED) {
bts_event_del(event, 0);
return -EBUSY;
}
}
return 0;
}
int intel_bts_interrupt(void)
{
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
struct perf_event *event = bts->handle.event;
struct bts_buffer *buf;
s64 old_head;
int err;
if (!event || !bts->started)
return 0;
buf = perf_get_aux(&bts->handle);
/*
* Skip snapshot counters: they don't use the interrupt, but
* there's no other way of telling, because the pointer will
* keep moving
*/
if (!buf || buf->snapshot)
return 0;
old_head = local_read(&buf->head);
bts_update(bts);
/* no new data */
if (old_head == local_read(&buf->head))
return 0;
perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
!!local_xchg(&buf->lost, 0));
buf = perf_aux_output_begin(&bts->handle, event);
if (!buf)
return 1;
err = bts_buffer_reset(buf, &bts->handle);
if (err)
perf_aux_output_end(&bts->handle, 0, false);
return 1;
}
int intel_bts_interrupt(void)
{
struct debug_store *ds = this_cpu_ptr(&cpu_hw_events)->ds;
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
struct perf_event *event = bts->handle.event;
struct bts_buffer *buf;
s64 old_head;
int err = -ENOSPC, handled = 0;
/*
* The only surefire way of knowing if this NMI is ours is by checking
* the write ptr against the PMI threshold.
*/
if (ds->bts_index >= ds->bts_interrupt_threshold)
handled = 1;
/*
* this is wrapped in intel_bts_enable_local/intel_bts_disable_local,
* so we can only be INACTIVE or STOPPED
*/
if (READ_ONCE(bts->state) == BTS_STATE_STOPPED)
return handled;
buf = perf_get_aux(&bts->handle);
if (!buf)
return handled;
/*
* Skip snapshot counters: they don't use the interrupt, but
* there's no other way of telling, because the pointer will
* keep moving
*/
if (buf->snapshot)
return 0;
old_head = local_read(&buf->head);
bts_update(bts);
/* no new data */
if (old_head == local_read(&buf->head))
return handled;
perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
!!local_xchg(&buf->lost, 0));
buf = perf_aux_output_begin(&bts->handle, event);
if (buf)
err = bts_buffer_reset(buf, &bts->handle);
if (err) {
WRITE_ONCE(bts->state, BTS_STATE_STOPPED);
if (buf) {
/*
* BTS_STATE_STOPPED should be visible before
* cleared handle::event
*/
barrier();
perf_aux_output_end(&bts->handle, 0, false);
}
}
return 1;
}