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SubjectRe: [RFC PATCH v2 4/7] libperf: Introduce perf_{evsel, evlist}__open_opt with extensible struct opts
On Fri, Mar 25, 2022 at 01:38:26PM +0900, Shunsuke Nakamura wrote:
> 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, ...)
> +

SNIP

> +
> +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;

please move the signal stuff handling into separate patch
together with the related fields in opts struct

thanks,
jirka

> +
> + 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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