[PATCH v2 0/3] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT

[PATCH v2 0/3] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT

[Charlie Jenkins]

Introduce a new perf ioctl key PERF_EVENT_IOC_INC_EVENT_LIMIT that
functions the same as PERF_EVENT_IOC_REFRESH, except it does not
immediately enable counters.

Also create a libperf API perf_evsel__refresh() to allow libperf users
access to this ioctl key.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
Changes in v2:
- Drop discussion about signal race condition
- Add new patch "libperf: Add perf_evsel__refresh() function"
- This newly added patch was pulled from a different series with
  modifications to fit the new ioctl key
-
https://lore.kernel.org/lkml/20240726-overflow_check_libperf-v2-0-7d154dcf6bea@rivosinc.com/
will be updated
- Link to v1: https://lore.kernel.org/r/20240724-perf_set_event_limit-v1-0-e680c93eca55@rivosinc.com

---
Charlie Jenkins (3):
      perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT
      perf: Document PERF_EVENT_IOC_INC_EVENT_LIMIT
      libperf: Add perf_evsel__refresh() function

 include/linux/perf_event.h               |  4 +--
 include/uapi/linux/perf_event.h          |  1 +
 kernel/events/core.c                     | 17 +++++++----
 tools/include/uapi/linux/perf_event.h    |  1 +
 tools/lib/perf/Documentation/libperf.txt |  2 ++
 tools/lib/perf/evsel.c                   | 49 ++++++++++++++++++++++++++------
 tools/lib/perf/include/perf/evsel.h      |  2 ++
 tools/lib/perf/libperf.map               |  2 ++
 tools/perf/design.txt                    |  5 ++++
 9 files changed, 67 insertions(+), 16 deletions(-)
---
base-commit: 0c3836482481200ead7b416ca80c68a29cfdaabd
change-id: 20240724-perf_set_event_limit-079f1b996376
-- 
- Charlie

[PATCH v2 1/3] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT

[Charlie Jenkins]

PERF_EVENT_IOC_REFRESH immediately enables after incrementing
event_limit.  Provide a new ioctl flag that allows programs to increment
event_limit without enabling the event. A usecase for this is to set an
event_limit in combination with enable_on_exec.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 include/linux/perf_event.h            |  4 ++--
 include/uapi/linux/perf_event.h       |  1 +
 kernel/events/core.c                  | 17 +++++++++++------
 tools/include/uapi/linux/perf_event.h |  1 +
 4 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index a5304ae8c654..40025a5eb98a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1103,7 +1103,7 @@ extern int perf_event_task_enable(void);
 
 extern void perf_pmu_resched(struct pmu *pmu);
 
-extern int perf_event_refresh(struct perf_event *event, int refresh);
+extern int perf_event_refresh(struct perf_event *event, int refresh, bool enable);
 extern void perf_event_update_userpage(struct perf_event *event);
 extern int perf_event_release_kernel(struct perf_event *event);
 extern struct perf_event *
@@ -1770,7 +1770,7 @@ static inline int perf_event_read_local(struct perf_event *event, u64 *value,
 static inline void perf_event_print_debug(void)				{ }
 static inline int perf_event_task_disable(void)				{ return -EINVAL; }
 static inline int perf_event_task_enable(void)				{ return -EINVAL; }
-static inline int perf_event_refresh(struct perf_event *event, int refresh)
+static inline int perf_event_refresh(struct perf_event *event, int refresh, bool enable)
 {
 	return -EINVAL;
 }
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 3a64499b0f5d..992f51effb27 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -560,6 +560,7 @@ struct perf_event_query_bpf {
 #define PERF_EVENT_IOC_PAUSE_OUTPUT		_IOW('$', 9, __u32)
 #define PERF_EVENT_IOC_QUERY_BPF		_IOWR('$', 10, struct perf_event_query_bpf *)
 #define PERF_EVENT_IOC_MODIFY_ATTRIBUTES	_IOW('$', 11, struct perf_event_attr *)
+#define PERF_EVENT_IOC_INC_EVENT_LIMIT		_IO ('$', 12)
 
 enum perf_event_ioc_flags {
 	PERF_IOC_FLAG_GROUP		= 1U << 0,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8f908f077935..b9d009733ace 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3142,7 +3142,7 @@ void perf_event_addr_filters_sync(struct perf_event *event)
 }
 EXPORT_SYMBOL_GPL(perf_event_addr_filters_sync);
 
-static int _perf_event_refresh(struct perf_event *event, int refresh)
+static int _perf_event_refresh(struct perf_event *event, int refresh, bool enable)
 {
 	/*
 	 * not supported on inherited events
@@ -3151,7 +3151,8 @@ static int _perf_event_refresh(struct perf_event *event, int refresh)
 		return -EINVAL;
 
 	atomic_add(refresh, &event->event_limit);
-	_perf_event_enable(event);
+	if (enable)
+		_perf_event_enable(event);
 
 	return 0;
 }
@@ -3159,13 +3160,13 @@ static int _perf_event_refresh(struct perf_event *event, int refresh)
 /*
  * See perf_event_disable()
  */
-int perf_event_refresh(struct perf_event *event, int refresh)
+int perf_event_refresh(struct perf_event *event, int refresh, bool enable)
 {
 	struct perf_event_context *ctx;
 	int ret;
 
 	ctx = perf_event_ctx_lock(event);
-	ret = _perf_event_refresh(event, refresh);
+	ret = _perf_event_refresh(event, refresh, enable);
 	perf_event_ctx_unlock(event, ctx);
 
 	return ret;
@@ -5920,7 +5921,7 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
 		break;
 
 	case PERF_EVENT_IOC_REFRESH:
-		return _perf_event_refresh(event, arg);
+		return _perf_event_refresh(event, arg, true);
 
 	case PERF_EVENT_IOC_PERIOD:
 	{
@@ -6006,6 +6007,10 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
 
 		return perf_event_modify_attr(event,  &new_attr);
 	}
+
+	case PERF_EVENT_IOC_INC_EVENT_LIMIT:
+		return _perf_event_refresh(event, arg, false);
+
 	default:
 		return -ENOTTY;
 	}
@@ -6721,7 +6726,7 @@ void perf_event_wakeup(struct perf_event *event)
 	ring_buffer_wakeup(event);
 
 	if (event->pending_kill) {
-		kill_fasync(perf_event_fasync(event), SIGIO, event->pending_kill);
+		kill_fasync(perf_event_fasync(event), SIGTRAP, event->pending_kill);
 		event->pending_kill = 0;
 	}
 }
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 3a64499b0f5d..992f51effb27 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -560,6 +560,7 @@ struct perf_event_query_bpf {
 #define PERF_EVENT_IOC_PAUSE_OUTPUT		_IOW('$', 9, __u32)
 #define PERF_EVENT_IOC_QUERY_BPF		_IOWR('$', 10, struct perf_event_query_bpf *)
 #define PERF_EVENT_IOC_MODIFY_ATTRIBUTES	_IOW('$', 11, struct perf_event_attr *)
+#define PERF_EVENT_IOC_INC_EVENT_LIMIT		_IO ('$', 12)
 
 enum perf_event_ioc_flags {
 	PERF_IOC_FLAG_GROUP		= 1U << 0,

-- 
2.45.0

[PATCH v2 2/3] perf: Document PERF_EVENT_IOC_INC_EVENT_LIMIT

[Charlie Jenkins]

Introduce PERF_EVENT_IOC_INC_EVENT_LIMIT and explain the differences
between it and PERF_EVENT_IOC_REFRESH.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 tools/perf/design.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index aa8cfeabb743..1626ae83785a 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -439,6 +439,11 @@ Additionally, non-inherited overflow counters can use
 
 to enable a counter for 'nr' events, after which it gets disabled again.
 
+PERF_EVENT_IOC_REFRESH will increment the event limit by 'nr' and enable the
+event. To increment the event limit without enabling it, use the following:
+
+	ioctl(fd, PERF_EVENT_IOC_INC_EVENT_LIMIT, nr);
+
 A process can enable or disable all the counter groups that are
 attached to it, using prctl:
 

-- 
2.45.0

[PATCH v2 3/3] libperf: Add perf_evsel__refresh() function

[Charlie Jenkins]

Introduce perf_evsel__refresh() to increment the overflow limit. Can
optionally enable the event immediately.

Co-developed-by: Shunsuke Nakamura <nakamura.shun@fujitsu.com>
Signed-off-by: Shunsuke Nakamura <nakamura.shun@fujitsu.com>
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 tools/lib/perf/Documentation/libperf.txt |  2 ++
 tools/lib/perf/evsel.c                   | 49 ++++++++++++++++++++++++++------
 tools/lib/perf/include/perf/evsel.h      |  2 ++
 tools/lib/perf/libperf.map               |  2 ++
 4 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt
index fcfb9499ef9c..a6c3bab5c995 100644
--- a/tools/lib/perf/Documentation/libperf.txt
+++ b/tools/lib/perf/Documentation/libperf.txt
@@ -147,6 +147,8 @@ SYNOPSIS
   int perf_evsel__enable_cpu(struct perf_evsel *evsel, int cpu_map_idx);
   int perf_evsel__disable(struct perf_evsel *evsel);
   int perf_evsel__disable_cpu(struct perf_evsel *evsel, int cpu_map_idx);
+  int perf_evsel__refresh(struct perf_evsel *evsel, int refresh, bool enable);
+  int perf_evsel__period(struct perf_evsel *evsel, int period);
   struct perf_cpu_map *perf_evsel__cpus(struct perf_evsel *evsel);
   struct perf_thread_map *perf_evsel__threads(struct perf_evsel *evsel);
   struct perf_event_attr *perf_evsel__attr(struct perf_evsel *evsel);
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index c07160953224..2b7ca7fa4998 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -18,6 +18,7 @@
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <asm/bug.h>
+#include "internal.h"
 
 void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr,
 		      int idx)
@@ -412,7 +413,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu_map_idx, int thread,
 	return 0;
 }
 
-static int perf_evsel__ioctl(struct perf_evsel *evsel, int ioc, void *arg,
+static int perf_evsel__ioctl(struct perf_evsel *evsel, int ioc, unsigned long arg,
 			     int cpu_map_idx, int thread)
 {
 	int *fd = FD(evsel, cpu_map_idx, thread);
@@ -424,7 +425,7 @@ static int perf_evsel__ioctl(struct perf_evsel *evsel, int ioc, void *arg,
 }
 
 static int perf_evsel__run_ioctl(struct perf_evsel *evsel,
-				 int ioc,  void *arg,
+				 int ioc, unsigned long arg,
 				 int cpu_map_idx)
 {
 	int thread;
@@ -441,7 +442,7 @@ static int perf_evsel__run_ioctl(struct perf_evsel *evsel,
 
 int perf_evsel__enable_cpu(struct perf_evsel *evsel, int cpu_map_idx)
 {
-	return perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_ENABLE, NULL, cpu_map_idx);
+	return perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_ENABLE, 0, cpu_map_idx);
 }
 
 int perf_evsel__enable_thread(struct perf_evsel *evsel, int thread)
@@ -451,7 +452,7 @@ int perf_evsel__enable_thread(struct perf_evsel *evsel, int thread)
 	int err;
 
 	perf_cpu_map__for_each_cpu(cpu, idx, evsel->cpus) {
-		err = perf_evsel__ioctl(evsel, PERF_EVENT_IOC_ENABLE, NULL, idx, thread);
+		err = perf_evsel__ioctl(evsel, PERF_EVENT_IOC_ENABLE, 0, idx, thread);
 		if (err)
 			return err;
 	}
@@ -465,13 +466,13 @@ int perf_evsel__enable(struct perf_evsel *evsel)
 	int err = 0;
 
 	for (i = 0; i < xyarray__max_x(evsel->fd) && !err; i++)
-		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_ENABLE, NULL, i);
+		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_ENABLE, 0, i);
 	return err;
 }
 
 int perf_evsel__disable_cpu(struct perf_evsel *evsel, int cpu_map_idx)
 {
-	return perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_DISABLE, NULL, cpu_map_idx);
+	return perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_DISABLE, 0, cpu_map_idx);
 }
 
 int perf_evsel__disable(struct perf_evsel *evsel)
@@ -480,7 +481,39 @@ int perf_evsel__disable(struct perf_evsel *evsel)
 	int err = 0;
 
 	for (i = 0; i < xyarray__max_x(evsel->fd) && !err; i++)
-		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_DISABLE, NULL, i);
+		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_DISABLE, 0, i);
+	return err;
+}
+
+int perf_evsel__refresh(struct perf_evsel *evsel, int refresh, bool enable)
+{
+	int i, ioc;
+	int err = 0;
+
+	ioc = enable ? PERF_EVENT_IOC_REFRESH : PERF_EVENT_IOC_INC_EVENT_LIMIT;
+
+	for (i = 0; i < xyarray__max_x(evsel->fd) && !err; i++)
+		err = perf_evsel__run_ioctl(evsel, ioc, refresh, i);
+	return err;
+}
+
+int perf_evsel__period(struct perf_evsel *evsel, __u64 period)
+{
+	struct perf_event_attr *attr;
+	int i;
+	int err = 0;
+
+	attr = perf_evsel__attr(evsel);
+
+	for (i = 0; i < xyarray__max_x(evsel->fd); i++) {
+		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_PERIOD,
+					    (unsigned long)&period, i);
+		if (err)
+			return err;
+	}
+
+	attr->sample_period = period;
+
 	return err;
 }
 
@@ -491,7 +524,7 @@ int perf_evsel__apply_filter(struct perf_evsel *evsel, const char *filter)
 	for (i = 0; i < perf_cpu_map__nr(evsel->cpus) && !err; i++)
 		err = perf_evsel__run_ioctl(evsel,
 				     PERF_EVENT_IOC_SET_FILTER,
-				     (void *)filter, i);
+				     (unsigned long)filter, i);
 	return err;
 }
 
diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
index 6f92204075c2..e562dd9f39e0 100644
--- a/tools/lib/perf/include/perf/evsel.h
+++ b/tools/lib/perf/include/perf/evsel.h
@@ -40,6 +40,8 @@ LIBPERF_API int perf_evsel__enable(struct perf_evsel *evsel);
 LIBPERF_API int perf_evsel__enable_cpu(struct perf_evsel *evsel, int cpu_map_idx);
 LIBPERF_API int perf_evsel__enable_thread(struct perf_evsel *evsel, int thread);
 LIBPERF_API int perf_evsel__disable(struct perf_evsel *evsel);
+LIBPERF_API int perf_evsel__refresh(struct perf_evsel *evsel, int refresh, bool enable);
+LIBPERF_API int perf_evsel__period(struct perf_evsel *evsel, __u64 period);
 LIBPERF_API int perf_evsel__disable_cpu(struct perf_evsel *evsel, int cpu_map_idx);
 LIBPERF_API struct perf_cpu_map *perf_evsel__cpus(struct perf_evsel *evsel);
 LIBPERF_API struct perf_thread_map *perf_evsel__threads(struct perf_evsel *evsel);
diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
index 2aa79b696032..bb7a48befdd5 100644
--- a/tools/lib/perf/libperf.map
+++ b/tools/lib/perf/libperf.map
@@ -34,6 +34,8 @@ LIBPERF_0.0.1 {
 		perf_evsel__munmap;
 		perf_evsel__mmap_base;
 		perf_evsel__read;
+		perf_evsel__refresh;
+		perf_evsel__period;
 		perf_evsel__cpus;
 		perf_evsel__threads;
 		perf_evsel__attr;

-- 
2.45.0

Re: [PATCH v2 0/3] perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT

[Charlie Jenkins]

On Wed, Aug 07, 2024 at 05:02:39PM -0700, Charlie Jenkins wrote:
> Introduce a new perf ioctl key PERF_EVENT_IOC_INC_EVENT_LIMIT that
> functions the same as PERF_EVENT_IOC_REFRESH, except it does not
> immediately enable counters.
> 
> Also create a libperf API perf_evsel__refresh() to allow libperf users
> access to this ioctl key.
> 
> Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
> Changes in v2:
> - Drop discussion about signal race condition
> - Add new patch "libperf: Add perf_evsel__refresh() function"
> - This newly added patch was pulled from a different series with
>   modifications to fit the new ioctl key
> -
> https://lore.kernel.org/lkml/20240726-overflow_check_libperf-v2-0-7d154dcf6bea@rivosinc.com/
> will be updated
> - Link to v1: https://lore.kernel.org/r/20240724-perf_set_event_limit-v1-0-e680c93eca55@rivosinc.com
> 
> ---
> Charlie Jenkins (3):
>       perf: Add PERF_EVENT_IOC_INC_EVENT_LIMIT
>       perf: Document PERF_EVENT_IOC_INC_EVENT_LIMIT
>       libperf: Add perf_evsel__refresh() function
> 
>  include/linux/perf_event.h               |  4 +--
>  include/uapi/linux/perf_event.h          |  1 +
>  kernel/events/core.c                     | 17 +++++++----
>  tools/include/uapi/linux/perf_event.h    |  1 +
>  tools/lib/perf/Documentation/libperf.txt |  2 ++
>  tools/lib/perf/evsel.c                   | 49 ++++++++++++++++++++++++++------
>  tools/lib/perf/include/perf/evsel.h      |  2 ++
>  tools/lib/perf/libperf.map               |  2 ++
>  tools/perf/design.txt                    |  5 ++++
>  9 files changed, 67 insertions(+), 16 deletions(-)
> ---
> base-commit: 0c3836482481200ead7b416ca80c68a29cfdaabd
> change-id: 20240724-perf_set_event_limit-079f1b996376
> -- 
> - Charlie
> 

I am interested in people's opinion of this. Let me know if there are
any concerns.

- Charlie