diff options
author | Andrii Nakryiko <andriin@fb.com> | 2019-07-02 01:58:57 +0200 |
---|---|---|
committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-07-05 22:37:30 +0200 |
commit | 63f2f5ee856ba9db751123bc5519be099a3849a7 (patch) | |
tree | 27a5a6a7e50f876ec260de8ac1c9fa4bd46f11ae /tools | |
parent | libbpf: introduce concept of bpf_link (diff) | |
download | linux-63f2f5ee856ba9db751123bc5519be099a3849a7.tar.xz linux-63f2f5ee856ba9db751123bc5519be099a3849a7.zip |
libbpf: add ability to attach/detach BPF program to perf event
bpf_program__attach_perf_event allows to attach BPF program to existing
perf event hook, providing most generic and most low-level way to attach BPF
programs. It returns struct bpf_link, which should be passed to
bpf_link__destroy to detach and free resources, associated with a link.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools')
-rw-r--r-- | tools/lib/bpf/libbpf.c | 63 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.h | 3 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf.map | 1 |
3 files changed, 67 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index f308690abd50..54ce22f9f777 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> @@ -3958,6 +3959,68 @@ int bpf_link__destroy(struct bpf_link *link) return err; } +struct bpf_link_fd { + struct bpf_link link; /* has to be at the top of struct */ + int fd; /* hook FD */ +}; + +static int bpf_link__destroy_perf_event(struct bpf_link *link) +{ + struct bpf_link_fd *l = (void *)link; + int err; + + err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0); + if (err) + err = -errno; + + close(l->fd); + return err; +} + +struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, + int pfd) +{ + char errmsg[STRERR_BUFSIZE]; + struct bpf_link_fd *link; + int prog_fd, err; + + if (pfd < 0) { + pr_warning("program '%s': invalid perf event FD %d\n", + bpf_program__title(prog, false), pfd); + return ERR_PTR(-EINVAL); + } + prog_fd = bpf_program__fd(prog); + if (prog_fd < 0) { + pr_warning("program '%s': can't attach BPF program w/o FD (did you load it?)\n", + bpf_program__title(prog, false)); + return ERR_PTR(-EINVAL); + } + + link = malloc(sizeof(*link)); + if (!link) + return ERR_PTR(-ENOMEM); + link->link.destroy = &bpf_link__destroy_perf_event; + link->fd = pfd; + + if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) { + err = -errno; + free(link); + 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_PTR(err); + } + if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { + err = -errno; + free(link); + 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_PTR(err); + } + return (struct bpf_link *)link; +} + 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 5082a5ebb0c2..1bf66c4a9330 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -169,6 +169,9 @@ struct bpf_link; LIBBPF_API int bpf_link__destroy(struct bpf_link *link); +LIBBPF_API struct bpf_link * +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 3cde850fc8da..756f5aa802e9 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -169,6 +169,7 @@ LIBBPF_0.0.4 { global: bpf_link__destroy; bpf_object__load_xattr; + bpf_program__attach_perf_event; btf_dump__dump_type; btf_dump__free; btf_dump__new; |