Revert "perf/core: Add aux_pause, aux_resume, aux_start_paused"

This reverts commit c61feda373 which is
commit 18d92bb57c39504d9da11c6ef604f58eb1d5a117 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I29205f8d540692f5415a1cd3e7fcf74076b2b3b8
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

include/linux/perf_event.h

@@ -170,12 +170,6 @@ struct hw_perf_event {
 		};
 		struct { /* aux / Intel-PT */
 			u64		aux_config;
-			/*
-			 * For AUX area events, aux_paused cannot be a state
-			 * flag because it can be updated asynchronously to
-			 * state.
-			 */
-			unsigned int	aux_paused;
 		};
 		struct { /* software */
 			struct hrtimer	hrtimer;
@@ -300,7 +294,6 @@ struct perf_event_pmu_context;
 #define PERF_PMU_CAP_NO_EXCLUDE			0x0040
 #define PERF_PMU_CAP_AUX_OUTPUT			0x0080
 #define PERF_PMU_CAP_EXTENDED_HW_TYPE		0x0100
-#define PERF_PMU_CAP_AUX_PAUSE			0x0200
 
 /**
  * pmu::scope
@@ -391,8 +384,6 @@ struct pmu {
 #define PERF_EF_START	0x01		/* start the counter when adding    */
 #define PERF_EF_RELOAD	0x02		/* reload the counter when starting */
 #define PERF_EF_UPDATE	0x04		/* update the counter when stopping */
-#define PERF_EF_PAUSE	0x08		/* AUX area event, pause tracing */
-#define PERF_EF_RESUME	0x10		/* AUX area event, resume tracing */
 
 	/*
 	 * Adds/Removes a counter to/from the PMU, can be done inside a
@@ -432,18 +423,6 @@ struct pmu {
 	 *
 	 * ->start() with PERF_EF_RELOAD will reprogram the counter
 	 *  value, must be preceded by a ->stop() with PERF_EF_UPDATE.
-	 *
-	 * ->stop() with PERF_EF_PAUSE will stop as simply as possible. Will not
-	 * overlap another ->stop() with PERF_EF_PAUSE nor ->start() with
-	 * PERF_EF_RESUME.
-	 *
-	 * ->start() with PERF_EF_RESUME will start as simply as possible but
-	 * only if the counter is not otherwise stopped. Will not overlap
-	 * another ->start() with PERF_EF_RESUME nor ->stop() with
-	 * PERF_EF_PAUSE.
-	 *
-	 * Notably, PERF_EF_PAUSE/PERF_EF_RESUME *can* be concurrent with other
-	 * ->stop()/->start() invocations, just not itself.
 	 */
 	void (*start)			(struct perf_event *event, int flags);
 	void (*stop)			(struct perf_event *event, int flags);
@@ -1724,13 +1703,6 @@ static inline bool has_aux(struct perf_event *event)
 	return event->pmu->setup_aux;
 }
 
-static inline bool has_aux_action(struct perf_event *event)
-{
-	return event->attr.aux_sample_size ||
-	       event->attr.aux_pause ||
-	       event->attr.aux_resume;
-}
-
 static inline bool is_write_backward(struct perf_event *event)
 {
 	return !!event->attr.write_backward;

include/uapi/linux/perf_event.h

@@ -511,16 +511,7 @@ struct perf_event_attr {
 	__u16	sample_max_stack;
 	__u16	__reserved_2;
 	__u32	aux_sample_size;
-
+	__u32	__reserved_3;
-	union {
-		__u32	aux_action;
-		struct {
-			__u32	aux_start_paused :  1, /* start AUX area tracing paused */
-				aux_pause        :  1, /* on overflow, pause AUX area tracing */
-				aux_resume       :  1, /* on overflow, resume AUX area tracing */
-				__reserved_3     : 29;
-		};
-	};
 
 	/*
 	 * User provided data if sigtrap=1, passed back to user via

kernel/events/core.c

@@ -2146,7 +2146,7 @@ static void perf_put_aux_event(struct perf_event *event)
 
 static bool perf_need_aux_event(struct perf_event *event)
 {
-	return event->attr.aux_output || has_aux_action(event);
+	return !!event->attr.aux_output || !!event->attr.aux_sample_size;
 }
 
 static int perf_get_aux_event(struct perf_event *event,
@@ -2171,10 +2171,6 @@ static int perf_get_aux_event(struct perf_event *event,
 	    !perf_aux_output_match(event, group_leader))
 		return 0;
 
-	if ((event->attr.aux_pause || event->attr.aux_resume) &&
-	    !(group_leader->pmu->capabilities & PERF_PMU_CAP_AUX_PAUSE))
-		return 0;
-
 	if (event->attr.aux_sample_size && !group_leader->pmu->snapshot_aux)
 		return 0;
 
@@ -8019,49 +8015,6 @@ void perf_prepare_header(struct perf_event_header *header,
 	WARN_ON_ONCE(header->size & 7);
 }
 
-static void __perf_event_aux_pause(struct perf_event *event, bool pause)
-{
-	if (pause) {
-		if (!event->hw.aux_paused) {
-			event->hw.aux_paused = 1;
-			event->pmu->stop(event, PERF_EF_PAUSE);
-		}
-	} else {
-		if (event->hw.aux_paused) {
-			event->hw.aux_paused = 0;
-			event->pmu->start(event, PERF_EF_RESUME);
-		}
-	}
-}
-
-static void perf_event_aux_pause(struct perf_event *event, bool pause)
-{
-	struct perf_buffer *rb;
-
-	if (WARN_ON_ONCE(!event))
-		return;
-
-	rb = ring_buffer_get(event);
-	if (!rb)
-		return;
-
-	scoped_guard (irqsave) {
-		/*
-		 * Guard against self-recursion here. Another event could trip
-		 * this same from NMI context.
-		 */
-		if (READ_ONCE(rb->aux_in_pause_resume))
-			break;
-
-		WRITE_ONCE(rb->aux_in_pause_resume, 1);
-		barrier();
-		__perf_event_aux_pause(event, pause);
-		barrier();
-		WRITE_ONCE(rb->aux_in_pause_resume, 0);
-	}
-	ring_buffer_put(rb);
-}
-
 static __always_inline int
 __perf_event_output(struct perf_event *event,
 		    struct perf_sample_data *data,
@@ -9865,12 +9818,9 @@ static int __perf_event_overflow(struct perf_event *event,
 
 	ret = __perf_event_account_interrupt(event, throttle);
 
-	if (event->attr.aux_pause)
-		perf_event_aux_pause(event->aux_event, true);
-
 	if (event->prog && event->prog->type == BPF_PROG_TYPE_PERF_EVENT &&
 	    !bpf_overflow_handler(event, data, regs))
-		goto out;
+		return ret;
 
 	/*
 	 * XXX event_limit might not quite work as expected on inherited
@@ -9932,9 +9882,6 @@ static int __perf_event_overflow(struct perf_event *event,
 		event->pending_wakeup = 1;
 		irq_work_queue(&event->pending_irq);
 	}
-out:
-	if (event->attr.aux_resume)
-		perf_event_aux_pause(event->aux_event, false);
 
 	return ret;
 }
@@ -12351,25 +12298,11 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 	}
 
 	if (event->attr.aux_output &&
-	    (!(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT) ||
+	    !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
-	     event->attr.aux_pause || event->attr.aux_resume)) {
 		err = -EOPNOTSUPP;
 		goto err_pmu;
 	}
 
-	if (event->attr.aux_pause && event->attr.aux_resume) {
-		err = -EINVAL;
-		goto err_pmu;
-	}
-
-	if (event->attr.aux_start_paused) {
-		if (!(pmu->capabilities & PERF_PMU_CAP_AUX_PAUSE)) {
-			err = -EOPNOTSUPP;
-			goto err_pmu;
-		}
-		event->hw.aux_paused = 1;
-	}
-
 	if (cgroup_fd != -1) {
 		err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
 		if (err)
@@ -13165,7 +13098,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
 	 * Grouping is not supported for kernel events, neither is 'AUX',
 	 * make sure the caller's intentions are adjusted.
 	 */
-	if (attr->aux_output || attr->aux_action)
+	if (attr->aux_output)
 		return ERR_PTR(-EINVAL);
 
 	event = perf_event_alloc(attr, cpu, task, NULL, NULL,

kernel/events/internal.h

@@ -52,7 +52,6 @@ struct perf_buffer {
 	void				(*free_aux)(void *);
 	refcount_t			aux_refcount;
 	int				aux_in_sampling;
-	int				aux_in_pause_resume;
 	void				**aux_pages;
 	void				*aux_priv;