| Message ID | 20190620230951.3155955-3-andriin@fb.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | libbpf: add tracing attach APIs | expand |
On 06/20, Andrii Nakryiko wrote: > bpf_program__attach_perf_event allows to attach BPF program to existing > perf event, providing most generic and most low-level way to attach BPF > programs. > > libbpf_perf_event_disable_and_close API is added to disable and close > existing perf event by its FD. > > Signed-off-by: Andrii Nakryiko <andriin@fb.com> > --- > tools/lib/bpf/libbpf.c | 41 ++++++++++++++++++++++++++++++++++++++++ > tools/lib/bpf/libbpf.h | 4 ++++ > tools/lib/bpf/libbpf.map | 2 ++ > 3 files changed, 47 insertions(+) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 8ce3beba8551..2bb1fa008be3 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -32,6 +32,7 @@ > #include <linux/limits.h> > #include <linux/perf_event.h> > #include <linux/ring_buffer.h> > +#include <sys/ioctl.h> > #include <sys/stat.h> > #include <sys/types.h> > #include <sys/vfs.h> > @@ -3928,6 +3929,46 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, > return 0; > } > [..] > +int libbpf_perf_event_disable_and_close(int pfd) nit: why not call it libbpf_perf_event_detach[_and_close]? It's usually attach/detach. > +{ > + int err; > + > + if (pfd < 0) > + return 0; > + > + err = ioctl(pfd, PERF_EVENT_IOC_DISABLE, 0); > + close(pfd); > + return err; > +} > + > +int bpf_program__attach_perf_event(struct bpf_program *prog, int pfd) > +{ > + char errmsg[STRERR_BUFSIZE]; > + int bpf_fd, err; > + > + bpf_fd = bpf_program__fd(prog); > + if (bpf_fd < 0) { > + pr_warning("program '%s': can't attach before loaded\n", > + bpf_program__title(prog, false)); > + return -EINVAL; > + } > + if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, bpf_fd) < 0) { > + err = -errno; > + pr_warning("program '%s': failed to attach to pfd %d: %s\n", > + bpf_program__title(prog, false), pfd, > + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); > + return err; > + } > + if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { > + err = -errno; > + pr_warning("program '%s': failed to enable pfd %d: %s\n", > + bpf_program__title(prog, false), pfd, > + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); > + return err; > + } > + return 0; > +} > + > enum bpf_perf_event_ret > bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size, > void **copy_mem, size_t *copy_size, > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index d639f47e3110..76db1bbc0dac 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -165,6 +165,10 @@ LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path); > LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path); > LIBBPF_API void bpf_program__unload(struct bpf_program *prog); > > +LIBBPF_API int libbpf_perf_event_disable_and_close(int pfd); > +LIBBPF_API int bpf_program__attach_perf_event(struct bpf_program *prog, > + int pfd); > + > struct bpf_insn; > > /* > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > index 2c6d835620d2..d27406982b5a 100644 > --- a/tools/lib/bpf/libbpf.map > +++ b/tools/lib/bpf/libbpf.map > @@ -172,5 +172,7 @@ LIBBPF_0.0.4 { > btf_dump__new; > btf__parse_elf; > bpf_object__load_xattr; > + bpf_program__attach_perf_event; > libbpf_num_possible_cpus; > + libbpf_perf_event_disable_and_close; > } LIBBPF_0.0.3; > -- > 2.17.1 >
On Thu, Jun 20, 2019 at 5:01 PM Stanislav Fomichev <sdf@fomichev.me> wrote: > > On 06/20, Andrii Nakryiko wrote: > > bpf_program__attach_perf_event allows to attach BPF program to existing > > perf event, providing most generic and most low-level way to attach BPF > > programs. > > > > libbpf_perf_event_disable_and_close API is added to disable and close > > existing perf event by its FD. > > > > Signed-off-by: Andrii Nakryiko <andriin@fb.com> > > --- > > tools/lib/bpf/libbpf.c | 41 ++++++++++++++++++++++++++++++++++++++++ > > tools/lib/bpf/libbpf.h | 4 ++++ > > tools/lib/bpf/libbpf.map | 2 ++ > > 3 files changed, 47 insertions(+) > > > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > > index 8ce3beba8551..2bb1fa008be3 100644 > > --- a/tools/lib/bpf/libbpf.c > > +++ b/tools/lib/bpf/libbpf.c > > @@ -32,6 +32,7 @@ > > #include <linux/limits.h> > > #include <linux/perf_event.h> > > #include <linux/ring_buffer.h> > > +#include <sys/ioctl.h> > > #include <sys/stat.h> > > #include <sys/types.h> > > #include <sys/vfs.h> > > @@ -3928,6 +3929,46 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, > > return 0; > > } > > > [..] > > +int libbpf_perf_event_disable_and_close(int pfd) > nit: why not call it libbpf_perf_event_detach[_and_close]? > It's usually attach/detach. I think detach is actually confusing for perf event. Here's what you do for tracing: 1. open perf event 2. enable perf event 3. attach BPF program to perf event ... 4. <is there a way to detach BPF program?> 5. disable perf event 6. close perf event So open/close event, enable/disable event, attach / (auto-detach on close right now) BPF program. It seems like there should be explicit "detach this BPF program from perf event without killing event itself", but I haven't found it. But my point is that for event open/close and enable/disable seems very complementary. > > > +{ > > + int err; > > + > > + if (pfd < 0) > > + return 0; > > + > > + err = ioctl(pfd, PERF_EVENT_IOC_DISABLE, 0); > > + close(pfd); > > + return err; > > +} > > + > > +int bpf_program__attach_perf_event(struct bpf_program *prog, int pfd) > > +{ > > + char errmsg[STRERR_BUFSIZE]; > > + int bpf_fd, err; > > + > > + bpf_fd = bpf_program__fd(prog); > > + if (bpf_fd < 0) { > > + pr_warning("program '%s': can't attach before loaded\n", > > + bpf_program__title(prog, false)); > > + return -EINVAL; > > + } > > + if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, bpf_fd) < 0) { > > + err = -errno; > > + pr_warning("program '%s': failed to attach to pfd %d: %s\n", > > + bpf_program__title(prog, false), pfd, > > + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); > > + return err; > > + } > > + if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { > > + err = -errno; > > + pr_warning("program '%s': failed to enable pfd %d: %s\n", > > + bpf_program__title(prog, false), pfd, > > + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); > > + return err; > > + } > > + return 0; > > +} > > + > > enum bpf_perf_event_ret > > bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size, > > void **copy_mem, size_t *copy_size, > > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > > index d639f47e3110..76db1bbc0dac 100644 > > --- a/tools/lib/bpf/libbpf.h > > +++ b/tools/lib/bpf/libbpf.h > > @@ -165,6 +165,10 @@ LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path); > > LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path); > > LIBBPF_API void bpf_program__unload(struct bpf_program *prog); > > > > +LIBBPF_API int libbpf_perf_event_disable_and_close(int pfd); > > +LIBBPF_API int bpf_program__attach_perf_event(struct bpf_program *prog, > > + int pfd); > > + > > struct bpf_insn; > > > > /* > > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > > index 2c6d835620d2..d27406982b5a 100644 > > --- a/tools/lib/bpf/libbpf.map > > +++ b/tools/lib/bpf/libbpf.map > > @@ -172,5 +172,7 @@ LIBBPF_0.0.4 { > > btf_dump__new; > > btf__parse_elf; > > bpf_object__load_xattr; > > + bpf_program__attach_perf_event; > > libbpf_num_possible_cpus; > > + libbpf_perf_event_disable_and_close; > > } LIBBPF_0.0.3; > > -- > > 2.17.1 > >
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 8ce3beba8551..2bb1fa008be3 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -32,6 +32,7 @@ #include <linux/limits.h> #include <linux/perf_event.h> #include <linux/ring_buffer.h> +#include <sys/ioctl.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/vfs.h> @@ -3928,6 +3929,46 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, return 0; } +int libbpf_perf_event_disable_and_close(int pfd) +{ + int err; + + if (pfd < 0) + return 0; + + err = ioctl(pfd, PERF_EVENT_IOC_DISABLE, 0); + close(pfd); + return err; +} + +int bpf_program__attach_perf_event(struct bpf_program *prog, int pfd) +{ + char errmsg[STRERR_BUFSIZE]; + int bpf_fd, err; + + bpf_fd = bpf_program__fd(prog); + if (bpf_fd < 0) { + pr_warning("program '%s': can't attach before loaded\n", + bpf_program__title(prog, false)); + return -EINVAL; + } + if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, bpf_fd) < 0) { + err = -errno; + pr_warning("program '%s': failed to attach to pfd %d: %s\n", + bpf_program__title(prog, false), pfd, + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + return err; + } + if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { + err = -errno; + pr_warning("program '%s': failed to enable pfd %d: %s\n", + bpf_program__title(prog, false), pfd, + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + return err; + } + return 0; +} + enum bpf_perf_event_ret bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size, void **copy_mem, size_t *copy_size, diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index d639f47e3110..76db1bbc0dac 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -165,6 +165,10 @@ LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path); LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path); LIBBPF_API void bpf_program__unload(struct bpf_program *prog); +LIBBPF_API int libbpf_perf_event_disable_and_close(int pfd); +LIBBPF_API int bpf_program__attach_perf_event(struct bpf_program *prog, + int pfd); + struct bpf_insn; /* diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 2c6d835620d2..d27406982b5a 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -172,5 +172,7 @@ LIBBPF_0.0.4 { btf_dump__new; btf__parse_elf; bpf_object__load_xattr; + bpf_program__attach_perf_event; libbpf_num_possible_cpus; + libbpf_perf_event_disable_and_close; } LIBBPF_0.0.3;
bpf_program__attach_perf_event allows to attach BPF program to existing perf event, providing most generic and most low-level way to attach BPF programs. libbpf_perf_event_disable_and_close API is added to disable and close existing perf event by its FD. Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/lib/bpf/libbpf.c | 41 ++++++++++++++++++++++++++++++++++++++++ tools/lib/bpf/libbpf.h | 4 ++++ tools/lib/bpf/libbpf.map | 2 ++ 3 files changed, 47 insertions(+)