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libbpf: Add bpf_cookie to perf_event, kprobe, uprobe, and tp attach APIs 

Wire through bpf_cookie for all attach APIs that use perf_event_open under the
hood:
  - for kprobes, extend existing bpf_kprobe_opts with bpf_cookie field;
  - for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
    pass bpf_cookie through opts.

For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
bpf_cookie is not supported either, return error and log warning for user.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-12-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2021-08-15 00:06:04 -07:00 committed by Daniel Borkmann
parent 3ec84f4b16
commit 47faff3717
3 changed files with 127 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
tools/lib/bpf/libbpf.c
View File

@ -9014,12 +9014,16 @@ static void bpf_link_perf_dealloc(struct bpf_link *link)
free(perf_link);
}
struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
struct bpf_link *bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,
const struct bpf_perf_event_opts *opts)
{
char errmsg[STRERR_BUFSIZE];
struct bpf_link_perf *link;
int prog_fd, link_fd = -1, err;
if (!OPTS_VALID(opts, bpf_perf_event_opts))
return libbpf_err_ptr(-EINVAL);
if (pfd < 0) {
pr_warn("prog '%s': invalid perf event FD %d\n",
prog->name, pfd);
@ -9040,7 +9044,10 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf
link->perf_event_fd = pfd;
if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {
link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, NULL);
DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
.perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));
link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
if (link_fd < 0) {
err = -errno;
pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
@ -9050,6 +9057,12 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf
}
link->link.fd = link_fd;
} else {
if (OPTS_GET(opts, bpf_cookie, 0)) {
pr_warn("prog '%s': user context value is not supported\n", prog->name);
err = -EOPNOTSUPP;
goto err_out;
}
if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
err = -errno;
pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
@ -9076,6 +9089,11 @@ err_out:
return libbpf_err_ptr(err);
}
struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
{
return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
}
/*
* this function is expected to parse integer in the range of [0, 2^31-1] from
* given file using scanf format string fmt. If actual parsed value is
@ -9184,8 +9202,9 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
struct bpf_link *
bpf_program__attach_kprobe_opts(struct bpf_program *prog,
const char *func_name,
struct bpf_kprobe_opts *opts)
const struct bpf_kprobe_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
unsigned long offset;
@ -9197,6 +9216,7 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog,
retprobe = OPTS_GET(opts, retprobe, false);
offset = OPTS_GET(opts, offset, 0);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
offset, -1 /* pid */);
@ -9206,7 +9226,7 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
link = bpf_program__attach_perf_event(prog, pfd);
link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
@ -9261,14 +9281,22 @@ static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
return link;
}
struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
bool retprobe, pid_t pid,
const char *binary_path,
size_t func_offset)
LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe_opts(struct bpf_program *prog, pid_t pid,
const char *binary_path, size_t func_offset,
const struct bpf_uprobe_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int pfd, err;
bool retprobe;
if (!OPTS_VALID(opts, bpf_uprobe_opts))
return libbpf_err_ptr(-EINVAL);
retprobe = OPTS_GET(opts, retprobe, false);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
pfd = perf_event_open_probe(true /* uprobe */, retprobe,
binary_path, func_offset, pid);
@ -9279,7 +9307,7 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
link = bpf_program__attach_perf_event(prog, pfd);
link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
@ -9292,6 +9320,16 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
return link;
}
struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
bool retprobe, pid_t pid,
const char *binary_path,
size_t func_offset)
{
DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
}
static int determine_tracepoint_id(const char *tp_category,
const char *tp_name)
{
@ -9342,14 +9380,21 @@ static int perf_event_open_tracepoint(const char *tp_category,
return pfd;
}
struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
const char *tp_category,
const char *tp_name)
struct bpf_link *bpf_program__attach_tracepoint_opts(struct bpf_program *prog,
const char *tp_category,
const char *tp_name,
const struct bpf_tracepoint_opts *opts)
{
DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int pfd, err;
if (!OPTS_VALID(opts, bpf_tracepoint_opts))
return libbpf_err_ptr(-EINVAL);
pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
pfd = perf_event_open_tracepoint(tp_category, tp_name);
if (pfd < 0) {
pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
@ -9357,7 +9402,7 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
link = bpf_program__attach_perf_event(prog, pfd);
link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
@ -9369,6 +9414,13 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
return link;
}
struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
const char *tp_category,
const char *tp_name)
{
return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
}
static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,
struct bpf_program *prog)
{

71
tools/lib/bpf/libbpf.h
View File

@ -104,17 +104,6 @@ struct bpf_object_open_opts {
};
#define bpf_object_open_opts__last_field btf_custom_path
struct bpf_kprobe_opts {
/* size of this struct, for forward/backward compatiblity */
size_t sz;
/* function's offset to install kprobe to */
unsigned long offset;
/* kprobe is return probe */
bool retprobe;
size_t :0;
};
#define bpf_kprobe_opts__last_field retprobe
LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
LIBBPF_API struct bpf_object *
bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts);
@ -255,24 +244,82 @@ LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
LIBBPF_API struct bpf_link *
bpf_program__attach(struct bpf_program *prog);
struct bpf_perf_event_opts {
/* size of this struct, for forward/backward compatiblity */
size_t sz;
/* custom user-provided value fetchable through bpf_get_attach_cookie() */
__u64 bpf_cookie;
};
#define bpf_perf_event_opts__last_field bpf_cookie
LIBBPF_API struct bpf_link *
bpf_program__attach_perf_event(struct bpf_program *prog, int pfd);
LIBBPF_API struct bpf_link *
bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,
const struct bpf_perf_event_opts *opts);
struct bpf_kprobe_opts {
/* size of this struct, for forward/backward compatiblity */
size_t sz;
/* custom user-provided value fetchable through bpf_get_attach_cookie() */
__u64 bpf_cookie;
/* function's offset to install kprobe to */
unsigned long offset;
/* kprobe is return probe */
bool retprobe;
size_t :0;
};
#define bpf_kprobe_opts__last_field retprobe
LIBBPF_API struct bpf_link *
bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,
const char *func_name);
LIBBPF_API struct bpf_link *
bpf_program__attach_kprobe_opts(struct bpf_program *prog,
const char *func_name,
struct bpf_kprobe_opts *opts);
const struct bpf_kprobe_opts *opts);
struct bpf_uprobe_opts {
/* size of this struct, for forward/backward compatiblity */
size_t sz;
/* custom user-provided value fetchable through bpf_get_attach_cookie() */
__u64 bpf_cookie;
/* uprobe is return probe, invoked at function return time */
bool retprobe;
size_t :0;
};
#define bpf_uprobe_opts__last_field retprobe
LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe,
pid_t pid, const char *binary_path,
size_t func_offset);
LIBBPF_API struct bpf_link *
bpf_program__attach_uprobe_opts(struct bpf_program *prog, pid_t pid,
const char *binary_path, size_t func_offset,
const struct bpf_uprobe_opts *opts);
struct bpf_tracepoint_opts {
/* size of this struct, for forward/backward compatiblity */
size_t sz;
/* custom user-provided value fetchable through bpf_get_attach_cookie() */
__u64 bpf_cookie;
};
#define bpf_tracepoint_opts__last_field bpf_cookie
LIBBPF_API struct bpf_link *
bpf_program__attach_tracepoint(struct bpf_program *prog,
const char *tp_category,
const char *tp_name);
LIBBPF_API struct bpf_link *
bpf_program__attach_tracepoint_opts(struct bpf_program *prog,
const char *tp_category,
const char *tp_name,
const struct bpf_tracepoint_opts *opts);
LIBBPF_API struct bpf_link *
bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
const char *tp_name);
LIBBPF_API struct bpf_link *

3
tools/lib/bpf/libbpf.map
View File

@ -374,6 +374,9 @@ LIBBPF_0.5.0 {
bpf_map__pin_path;
bpf_map_lookup_and_delete_elem_flags;
bpf_program__attach_kprobe_opts;
bpf_program__attach_perf_event_opts;
bpf_program__attach_tracepoint_opts;
bpf_program__attach_uprobe_opts;
bpf_object__gen_loader;
btf__load_from_kernel_by_id;
btf__load_from_kernel_by_id_split;