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Subject[RFC PATCH v2 4/7] libperf: Introduce perf_{evsel, evlist}__open_opt with extensible struct opts
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Introduce perf_{evsel, evlist}__open_opt with extensible structure opts.
The mechanism of the extensible structure opts imitates
tools/lib/bpf/libbpf.h. This allows the user to set the open_flags
specified in perf_event_open and a signal handler to receive overflow
notifications for sampling events.

Signed-off-by: Shunsuke Nakamura <nakamura.shun@fujitsu.com>
---
tools/lib/perf/Documentation/libperf.txt | 14 +++
tools/lib/perf/evlist.c | 20 +++++
tools/lib/perf/evsel.c | 105 +++++++++++++++++++++++
tools/lib/perf/include/perf/evlist.h | 3 +
tools/lib/perf/include/perf/evsel.h | 26 ++++++
tools/lib/perf/internal.h | 44 ++++++++++
tools/lib/perf/libperf.map | 2 +
7 files changed, 214 insertions(+)

diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt
index ae55e62fc4ce..700c1ce15159 100644
--- a/tools/lib/perf/Documentation/libperf.txt
+++ b/tools/lib/perf/Documentation/libperf.txt
@@ -131,6 +131,20 @@ SYNOPSIS
};
};

+ struct perf_evsel_open_opts {
+ /* size of this struct, for forward/backward compatibility */
+ size_t sz;
+
+ unsigned long open_flags; /* perf_event_open flags */
+ int flags; /* fcntl flags */
+ unsigned int signal;
+ int owner_type;
+ struct sigaction *sig;
+ };
+ #define perf_evsel_open_opts__last_field sig
+
+ #define LIBPERF_OPTS(TYPE, NAME, ...)
+
struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr);
void perf_evsel__delete(struct perf_evsel *evsel);
int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index 9a770bfdc804..6f136905d249 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -666,3 +666,23 @@ void perf_evlist__set_leader(struct perf_evlist *evlist)
__perf_evlist__set_leader(&evlist->entries, first);
}
}
+
+int perf_evlist__open_opts(struct perf_evlist *evlist,
+ struct perf_evsel_open_opts *opts)
+{
+ struct perf_evsel *evsel;
+ int err;
+
+ perf_evlist__for_each_entry(evlist, evsel) {
+ err = perf_evsel__open_opts(evsel, evsel->cpus,
+ evsel->threads, opts);
+ if (err < 0)
+ goto out_err;
+ }
+
+ return 0;
+
+out_err:
+ perf_evlist__close(evlist);
+ return err;
+}
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index b17842581dea..db9b7274feb5 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -1,4 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
#include <errno.h>
#include <unistd.h>
#include <sys/syscall.h>
@@ -16,8 +19,12 @@
#include <internal/lib.h>
#include <linux/string.h>
#include <sys/ioctl.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <sys/types.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)
@@ -511,3 +518,101 @@ void perf_counts_values__scale(struct perf_counts_values *count,
if (pscaled)
*pscaled = scaled;
}
+
+static int perf_evsel__run_fcntl(struct perf_evsel *evsel,
+ unsigned int cmd, unsigned long arg,
+ int cpu_map_idx)
+{
+ int thread;
+
+ for (thread = 0; thread < xyarray__max_y(evsel->fd); thread++) {
+ int err;
+ int *fd = FD(evsel, cpu_map_idx, thread);
+
+ if (!fd || *fd < 0)
+ return -1;
+
+ err = fcntl(*fd, cmd, arg);
+
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int perf_evsel__set_signal_handler(struct perf_evsel *evsel,
+ struct perf_evsel_open_opts *opts)
+{
+ unsigned int flags;
+ unsigned int signal;
+ struct f_owner_ex owner;
+ struct sigaction *sig;
+ int cpu_map_idx;
+ int err = 0;
+
+ flags = OPTS_GET(opts, flags, (O_RDWR | O_NONBLOCK | O_ASYNC));
+ signal = OPTS_GET(opts, signal, SIGIO);
+ owner.type = OPTS_GET(opts, owner_type, F_OWNER_PID);
+ sig = OPTS_GET(opts, sig, NULL);
+
+ if (flags == 0 && signal == 0 && !owner.type == 0 && sig == 0)
+ return err;
+
+ err = sigaction(signal, sig, NULL);
+ if (err)
+ return err;
+
+ switch (owner.type) {
+ case F_OWNER_PID:
+ owner.pid = getpid();
+ break;
+ case F_OWNER_TID:
+ owner.pid = syscall(SYS_gettid);
+ break;
+ case F_OWNER_PGRP:
+ default:
+ return -1;
+ }
+
+ for (cpu_map_idx = 0; cpu_map_idx < xyarray__max_x(evsel->fd); cpu_map_idx++) {
+ err = perf_evsel__run_fcntl(evsel, F_SETFL, flags, cpu_map_idx);
+ if (err)
+ return err;
+
+ err = perf_evsel__run_fcntl(evsel, F_SETSIG, signal, cpu_map_idx);
+ if (err)
+ return err;
+
+ err = perf_evsel__run_fcntl(evsel, F_SETOWN_EX,
+ (unsigned long)&owner, cpu_map_idx);
+ if (err)
+ return err;
+ }
+
+ return err;
+}
+
+int perf_evsel__open_opts(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
+ struct perf_thread_map *threads,
+ struct perf_evsel_open_opts *opts)
+{
+ int err = 0;
+
+ if (!OPTS_VALID(opts, perf_evsel_open_opts)) {
+ err = -EINVAL;
+ return err;
+ }
+
+ evsel->open_flags = OPTS_GET(opts, open_flags, 0);
+
+ err = perf_evsel__open(evsel, cpus, threads);
+ if (err)
+ return err;
+
+ err = perf_evsel__set_signal_handler(evsel, opts);
+ if (err)
+ return err;
+
+ return err;
+}
diff --git a/tools/lib/perf/include/perf/evlist.h b/tools/lib/perf/include/perf/evlist.h
index 9ca399d49bb4..6eff1e9b3481 100644
--- a/tools/lib/perf/include/perf/evlist.h
+++ b/tools/lib/perf/include/perf/evlist.h
@@ -9,6 +9,7 @@ struct perf_evlist;
struct perf_evsel;
struct perf_cpu_map;
struct perf_thread_map;
+struct perf_evsel_open_opts;

LIBPERF_API void perf_evlist__add(struct perf_evlist *evlist,
struct perf_evsel *evsel);
@@ -47,4 +48,6 @@ LIBPERF_API struct perf_mmap *perf_evlist__next_mmap(struct perf_evlist *evlist,
(pos) = perf_evlist__next_mmap((evlist), (pos), overwrite))

LIBPERF_API void perf_evlist__set_leader(struct perf_evlist *evlist);
+LIBPERF_API int perf_evlist__open_opts(struct perf_evlist *evlist,
+ struct perf_evsel_open_opts *opts);
#endif /* __LIBPERF_EVLIST_H */
diff --git a/tools/lib/perf/include/perf/evsel.h b/tools/lib/perf/include/perf/evsel.h
index 360ced734add..ecf30bc6303f 100644
--- a/tools/lib/perf/include/perf/evsel.h
+++ b/tools/lib/perf/include/perf/evsel.h
@@ -5,6 +5,7 @@
#include <stdint.h>
#include <perf/core.h>
#include <stdbool.h>
+#include <signal.h>
#include <linux/types.h>

struct perf_evsel;
@@ -23,6 +24,27 @@ struct perf_counts_values {
};
};

+struct perf_evsel_open_opts {
+ /* size of this struct, for forward/backward compatibility */
+ size_t sz;
+
+ unsigned long open_flags; /* perf_event_open flags */
+ int flags; /* fcntl flags */
+ unsigned int signal;
+ int owner_type;
+ struct sigaction *sig;
+};
+#define perf_evsel_open_opts__last_field sig
+
+#define LIBPERF_OPTS(TYPE, NAME, ...) \
+ struct TYPE NAME = ({ \
+ memset(&NAME, 0, sizeof(struct TYPE)); \
+ (struct TYPE) { \
+ .sz = sizeof(struct TYPE), \
+ __VA_ARGS__ \
+ }; \
+ })
+
LIBPERF_API struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr);
LIBPERF_API void perf_evsel__delete(struct perf_evsel *evsel);
LIBPERF_API int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
@@ -48,5 +70,9 @@ LIBPERF_API struct perf_thread_map *perf_evsel__threads(struct perf_evsel *evsel
LIBPERF_API struct perf_event_attr *perf_evsel__attr(struct perf_evsel *evsel);
LIBPERF_API void perf_counts_values__scale(struct perf_counts_values *count,
bool scale, __s8 *pscaled);
+LIBPERF_API int perf_evsel__open_opts(struct perf_evsel *evsel,
+ struct perf_cpu_map *cpus,
+ struct perf_thread_map *threads,
+ struct perf_evsel_open_opts *opts);

#endif /* __LIBPERF_EVSEL_H */
diff --git a/tools/lib/perf/internal.h b/tools/lib/perf/internal.h
index 2c27e158de6b..637bf6793c26 100644
--- a/tools/lib/perf/internal.h
+++ b/tools/lib/perf/internal.h
@@ -20,4 +20,48 @@ do { \
#define pr_debug2(fmt, ...) __pr(LIBPERF_DEBUG2, fmt, ##__VA_ARGS__)
#define pr_debug3(fmt, ...) __pr(LIBPERF_DEBUG3, fmt, ##__VA_ARGS__)

+static inline bool libperf_is_mem_zeroed(const char *p, ssize_t len)
+{
+ while (len > 0) {
+ if (*p)
+ return false;
+ p++;
+ len--;
+ }
+ return true;
+}
+
+static inline bool libperf_validate_opts(const char *opts,
+ size_t opts_sz, size_t user_sz,
+ const char *type_name)
+{
+ if (user_sz < sizeof(size_t)) {
+ pr_warning("%s size (%zu) is too small\n", type_name, user_sz);
+ return false;
+ }
+ if (!libperf_is_mem_zeroed(opts + opts_sz, (ssize_t)user_sz - opts_sz)) {
+ pr_warning("%s has non-zero extra bytes\n", type_name);
+ return false;
+ }
+ return true;
+}
+
+# define offsetofend(TYPE, FIELD) \
+ (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
+
+#define OPTS_VALID(opts, type) \
+ (!(opts) || libperf_validate_opts((const char *)opts, \
+ offsetofend(struct type, \
+ type##__last_field), \
+ (opts)->sz, #type))
+#define OPTS_HAS(opts, field) \
+ ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
+#define OPTS_GET(opts, field, fallback_value) \
+ (OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
+#define OPTS_SET(opts, field, value) \
+ do { \
+ if (OPTS_HAS(opts, field)) \
+ (opts)->field = value; \
+ } while (0)
+
#endif /* __LIBPERF_INTERNAL_H */
diff --git a/tools/lib/perf/libperf.map b/tools/lib/perf/libperf.map
index ab0f44e9bb57..534614fbbb26 100644
--- a/tools/lib/perf/libperf.map
+++ b/tools/lib/perf/libperf.map
@@ -24,6 +24,7 @@ LIBPERF_0.0.1 {
perf_evsel__enable;
perf_evsel__disable;
perf_evsel__open;
+ perf_evsel__open_opts;
perf_evsel__close;
perf_evsel__mmap;
perf_evsel__munmap;
@@ -39,6 +40,7 @@ LIBPERF_0.0.1 {
perf_evlist__new;
perf_evlist__delete;
perf_evlist__open;
+ perf_evlist__open_opts;
perf_evlist__close;
perf_evlist__enable;
perf_evlist__disable;
--
2.25.1
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