Re: [PATCH 2/4] perf: Keep AUX flags in the output handle

From: Mathieu Poirier
Date: Mon Feb 20 2017 - 15:48:46 EST

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On 20 February 2017 at 06:33, Alexander Shishkin
<alexander.shishkin@xxxxxxxxxxxxxxx> wrote:
> From: Will Deacon <will.deacon@xxxxxxx>
>
> In preparation for adding more flags to perf AUX records, introduce a
> separate API for setting the flags for a session, rather than appending
> more bool arguments to perf_aux_output_end. This allows to set each
> flag at the time a corresponding condition is detected, instead of
> tracking it in each driver's private state.
>
> Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> ---
> arch/x86/events/intel/bts.c | 16 +++++------
> arch/x86/events/intel/pt.c | 17 ++++++------
> arch/x86/events/intel/pt.h | 1 -
> drivers/hwtracing/coresight/coresight-etb10.c | 7 +++--
> drivers/hwtracing/coresight/coresight-etm-perf.c | 9 +++----
> drivers/hwtracing/coresight/coresight-priv.h | 2 --
> drivers/hwtracing/coresight/coresight-tmc-etf.c | 7 +++--

For the CS files:
Acked-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>

> include/linux/coresight.h | 2 +-
> include/linux/perf_event.h | 8 +++---
> kernel/events/ring_buffer.c | 34 ++++++++++++++++--------
> 10 files changed, 55 insertions(+), 48 deletions(-)
>
> diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
> index 982c9e31da..8ae8c5ce3a 100644
> --- a/arch/x86/events/intel/bts.c
> +++ b/arch/x86/events/intel/bts.c
> @@ -63,7 +63,6 @@ struct bts_buffer {
> unsigned int cur_buf;
> bool snapshot;
> local_t data_size;
> - local_t lost;
> local_t head;
> unsigned long end;
> void **data_pages;
> @@ -199,7 +198,8 @@ static void bts_update(struct bts_ctx *bts)
> return;
>
> if (ds->bts_index >= ds->bts_absolute_maximum)
> - local_inc(&buf->lost);
> + perf_aux_output_flag(&bts->handle,
> + PERF_AUX_FLAG_TRUNCATED);
>
> /*
> * old and head are always in the same physical buffer, so we
> @@ -276,7 +276,7 @@ static void bts_event_start(struct perf_event *event, int flags)
> return;
>
> fail_end_stop:
> - perf_aux_output_end(&bts->handle, 0, false);
> + perf_aux_output_end(&bts->handle, 0);
>
> fail_stop:
> event->hw.state = PERF_HES_STOPPED;
> @@ -319,9 +319,8 @@ static void bts_event_stop(struct perf_event *event, int flags)
> bts->handle.head =
> local_xchg(&buf->data_size,
> buf->nr_pages << PAGE_SHIFT);
> -
> - perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
> - !!local_xchg(&buf->lost, 0));
> + perf_aux_output_end(&bts->handle,
> + local_xchg(&buf->data_size, 0));
> }
>
> cpuc->ds->bts_index = bts->ds_back.bts_buffer_base;
> @@ -484,8 +483,7 @@ int intel_bts_interrupt(void)
> 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));
> + perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0));
>
> buf = perf_aux_output_begin(&bts->handle, event);
> if (buf)
> @@ -500,7 +498,7 @@ int intel_bts_interrupt(void)
> * cleared handle::event
> */
> barrier();
> - perf_aux_output_end(&bts->handle, 0, false);
> + perf_aux_output_end(&bts->handle, 0);
> }
> }
>
> diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
> index d92a60ef08..a2d0050fde 100644
> --- a/arch/x86/events/intel/pt.c
> +++ b/arch/x86/events/intel/pt.c
> @@ -823,7 +823,8 @@ static void pt_handle_status(struct pt *pt)
> */
> if (!pt_cap_get(PT_CAP_topa_multiple_entries) ||
> buf->output_off == sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size)) {
> - local_inc(&buf->lost);
> + perf_aux_output_flag(&pt->handle,
> + PERF_AUX_FLAG_TRUNCATED);
> advance++;
> }
> }
> @@ -916,8 +917,10 @@ static int pt_buffer_reset_markers(struct pt_buffer *buf,
>
> /* can't stop in the middle of an output region */
> if (buf->output_off + handle->size + 1 <
> - sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size))
> + sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size)) {
> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> return -EINVAL;
> + }
>
>
> /* single entry ToPA is handled by marking all regions STOP=1 INT=1 */
> @@ -1269,8 +1272,7 @@ void intel_pt_interrupt(void)
>
> pt_update_head(pt);
>
> - perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0),
> - local_xchg(&buf->lost, 0));
> + perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0));
>
> if (!event->hw.state) {
> int ret;
> @@ -1285,7 +1287,7 @@ void intel_pt_interrupt(void)
> /* snapshot counters don't use PMI, so it's safe */
> ret = pt_buffer_reset_markers(buf, &pt->handle);
> if (ret) {
> - perf_aux_output_end(&pt->handle, 0, true);
> + perf_aux_output_end(&pt->handle, 0);
> return;
> }
>
> @@ -1357,7 +1359,7 @@ static void pt_event_start(struct perf_event *event, int mode)
> return;
>
> fail_end_stop:
> - perf_aux_output_end(&pt->handle, 0, true);
> + perf_aux_output_end(&pt->handle, 0);
> fail_stop:
> hwc->state = PERF_HES_STOPPED;
> }
> @@ -1398,8 +1400,7 @@ static void pt_event_stop(struct perf_event *event, int mode)
> pt->handle.head =
> local_xchg(&buf->data_size,
> buf->nr_pages << PAGE_SHIFT);
> - perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0),
> - local_xchg(&buf->lost, 0));
> + perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0));
> }
> }
>
> diff --git a/arch/x86/events/intel/pt.h b/arch/x86/events/intel/pt.h
> index fa81f8d8ed..25fa9710f4 100644
> --- a/arch/x86/events/intel/pt.h
> +++ b/arch/x86/events/intel/pt.h
> @@ -144,7 +144,6 @@ struct pt_buffer {
> size_t output_off;
> unsigned long nr_pages;
> local_t data_size;
> - local_t lost;
> local64_t head;
> bool snapshot;
> unsigned long stop_pos, intr_pos;
> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
> index d7325c6534..82c8ddcf09 100644
> --- a/drivers/hwtracing/coresight/coresight-etb10.c
> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
> @@ -321,7 +321,7 @@ static int etb_set_buffer(struct coresight_device *csdev,
>
> static unsigned long etb_reset_buffer(struct coresight_device *csdev,
> struct perf_output_handle *handle,
> - void *sink_config, bool *lost)
> + void *sink_config)
> {
> unsigned long size = 0;
> struct cs_buffers *buf = sink_config;
> @@ -343,7 +343,6 @@ static unsigned long etb_reset_buffer(struct coresight_device *csdev,
> * resetting parameters here and squaring off with the ring
> * buffer API in the tracer PMU is fine.
> */
> - *lost = !!local_xchg(&buf->lost, 0);
> size = local_xchg(&buf->data_size, 0);
> }
>
> @@ -385,7 +384,7 @@ static void etb_update_buffer(struct coresight_device *csdev,
> (unsigned long)write_ptr);
>
> write_ptr &= ~(ETB_FRAME_SIZE_WORDS - 1);
> - local_inc(&buf->lost);
> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> }
>
> /*
> @@ -396,7 +395,7 @@ static void etb_update_buffer(struct coresight_device *csdev,
> */
> status = readl_relaxed(drvdata->base + ETB_STATUS_REG);
> if (status & ETB_STATUS_RAM_FULL) {
> - local_inc(&buf->lost);
> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> to_read = capacity;
> read_ptr = write_ptr;
> } else {
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index 70eaa74dc2..47ea0eee67 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -301,7 +301,8 @@ static void etm_event_start(struct perf_event *event, int flags)
> return;
>
> fail_end_stop:
> - perf_aux_output_end(handle, 0, true);
> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> + perf_aux_output_end(handle, 0);
> fail:
> event->hw.state = PERF_HES_STOPPED;
> goto out;
> @@ -309,7 +310,6 @@ static void etm_event_start(struct perf_event *event, int flags)
>
> static void etm_event_stop(struct perf_event *event, int mode)
> {
> - bool lost;
> int cpu = smp_processor_id();
> unsigned long size;
> struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
> @@ -347,10 +347,9 @@ static void etm_event_stop(struct perf_event *event, int mode)
> return;
>
> size = sink_ops(sink)->reset_buffer(sink, handle,
> - event_data->snk_config,
> - &lost);
> + event_data->snk_config);
>
> - perf_aux_output_end(handle, size, lost);
> + perf_aux_output_end(handle, size);
> }
>
> /* Disabling the path make its elements available to other sessions */
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index ef9d8e93e3..5f662d8205 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -76,7 +76,6 @@ enum cs_mode {
> * @nr_pages: max number of pages granted to us
> * @offset: offset within the current buffer
> * @data_size: how much we collected in this run
> - * @lost: other than zero if we had a HW buffer wrap around
> * @snapshot: is this run in snapshot mode
> * @data_pages: a handle the ring buffer
> */
> @@ -85,7 +84,6 @@ struct cs_buffers {
> unsigned int nr_pages;
> unsigned long offset;
> local_t data_size;
> - local_t lost;
> bool snapshot;
> void **data_pages;
> };
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index 1549436e24..aec61a6d5c 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -329,7 +329,7 @@ static int tmc_set_etf_buffer(struct coresight_device *csdev,
>
> static unsigned long tmc_reset_etf_buffer(struct coresight_device *csdev,
> struct perf_output_handle *handle,
> - void *sink_config, bool *lost)
> + void *sink_config)
> {
> long size = 0;
> struct cs_buffers *buf = sink_config;
> @@ -350,7 +350,6 @@ static unsigned long tmc_reset_etf_buffer(struct coresight_device *csdev,
> * resetting parameters here and squaring off with the ring
> * buffer API in the tracer PMU is fine.
> */
> - *lost = !!local_xchg(&buf->lost, 0);
> size = local_xchg(&buf->data_size, 0);
> }
>
> @@ -389,7 +388,7 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,
> */
> status = readl_relaxed(drvdata->base + TMC_STS);
> if (status & TMC_STS_FULL) {
> - local_inc(&buf->lost);
> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> to_read = drvdata->size;
> } else {
> to_read = CIRC_CNT(write_ptr, read_ptr, drvdata->size);
> @@ -434,7 +433,7 @@ static void tmc_update_etf_buffer(struct coresight_device *csdev,
> read_ptr -= drvdata->size;
> /* Tell the HW */
> writel_relaxed(read_ptr, drvdata->base + TMC_RRP);
> - local_inc(&buf->lost);
> + perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> }
>
> cur = buf->cur;
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index 2a5982c37d..035c16c9a5 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -201,7 +201,7 @@ struct coresight_ops_sink {
> void *sink_config);
> unsigned long (*reset_buffer)(struct coresight_device *csdev,
> struct perf_output_handle *handle,
> - void *sink_config, bool *lost);
> + void *sink_config);
> void (*update_buffer)(struct coresight_device *csdev,
> struct perf_output_handle *handle,
> void *sink_config);
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index a39564314e..cdbaa88dc8 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -812,6 +812,7 @@ struct perf_output_handle {
> struct ring_buffer *rb;
> unsigned long wakeup;
> unsigned long size;
> + u64 aux_flags;
> union {
> void *addr;
> unsigned long head;
> @@ -860,10 +861,11 @@ perf_cgroup_from_task(struct task_struct *task, struct perf_event_context *ctx)
> extern void *perf_aux_output_begin(struct perf_output_handle *handle,
> struct perf_event *event);
> extern void perf_aux_output_end(struct perf_output_handle *handle,
> - unsigned long size, bool truncated);
> + unsigned long size);
> extern int perf_aux_output_skip(struct perf_output_handle *handle,
> unsigned long size);
> extern void *perf_get_aux(struct perf_output_handle *handle);
> +extern void perf_aux_output_flag(struct perf_output_handle *handle, u64 flags);
>
> extern int perf_pmu_register(struct pmu *pmu, const char *name, int type);
> extern void perf_pmu_unregister(struct pmu *pmu);
> @@ -1278,8 +1280,8 @@ static inline void *
> perf_aux_output_begin(struct perf_output_handle *handle,
> struct perf_event *event) { return NULL; }
> static inline void
> -perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
> - bool truncated) { }
> +perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
> + { }
> static inline int
> perf_aux_output_skip(struct perf_output_handle *handle,
> unsigned long size) { return -EINVAL; }
> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
> index 6415807169..f3ebafe060 100644
> --- a/kernel/events/ring_buffer.c
> +++ b/kernel/events/ring_buffer.c
> @@ -297,6 +297,19 @@ ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
> rb->paused = 1;
> }
>
> +void perf_aux_output_flag(struct perf_output_handle *handle, u64 flags)
> +{
> + /*
> + * OVERWRITE is determined by perf_aux_output_end() and can't
> + * be passed in directly.
> + */
> + if (WARN_ON_ONCE(flags & PERF_AUX_FLAG_OVERWRITE))
> + return;
> +
> + handle->aux_flags |= flags;
> +}
> +EXPORT_SYMBOL_GPL(perf_aux_output_flag);
> +
> /*
> * This is called before hardware starts writing to the AUX area to
> * obtain an output handle and make sure there's room in the buffer.
> @@ -360,6 +373,7 @@ void *perf_aux_output_begin(struct perf_output_handle *handle,
> handle->event = event;
> handle->head = aux_head;
> handle->size = 0;
> + handle->aux_flags = 0;
>
> /*
> * In overwrite mode, AUX data stores do not depend on aux_tail,
> @@ -409,34 +423,32 @@ EXPORT_SYMBOL_GPL(perf_aux_output_begin);
> * of the AUX buffer management code is that after pmu::stop(), the AUX
> * transaction must be stopped and therefore drop the AUX reference count.
> */
> -void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
> - bool truncated)
> +void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
> {
> struct ring_buffer *rb = handle->rb;
> - bool wakeup = truncated;
> + bool wakeup = !!handle->aux_flags;
> unsigned long aux_head;
> - u64 flags = 0;
> -
> - if (truncated)
> - flags |= PERF_AUX_FLAG_TRUNCATED;
>
> /* in overwrite mode, driver provides aux_head via handle */
> if (rb->aux_overwrite) {
> - flags |= PERF_AUX_FLAG_OVERWRITE;
> + handle->aux_flags |= PERF_AUX_FLAG_OVERWRITE;
>
> aux_head = handle->head;
> local_set(&rb->aux_head, aux_head);
> } else {
> + handle->aux_flags &= ~PERF_AUX_FLAG_OVERWRITE;
> +
> aux_head = local_read(&rb->aux_head);
> local_add(size, &rb->aux_head);
> }
>
> - if (size || flags) {
> + if (size || handle->aux_flags) {
> /*
> * Only send RECORD_AUX if we have something useful to communicate
> */
>
> - perf_event_aux_event(handle->event, aux_head, size, flags);
> + perf_event_aux_event(handle->event, aux_head, size,
> + handle->aux_flags);
> }
>
> aux_head = rb->user_page->aux_head = local_read(&rb->aux_head);
> @@ -447,7 +459,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
> }
>
> if (wakeup) {
> - if (truncated)
> + if (handle->aux_flags & PERF_AUX_FLAG_TRUNCATED)
> handle->event->pending_disable = 1;
> perf_output_wakeup(handle);
> }
> --
> 2.11.0
>

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