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libbpf: Add support for kprobe session attach

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Adding support to attach program in kprobe session mode
with bpf_program__attach_kprobe_multi_opts function.

Adding session bool to bpf_kprobe_multi_opts struct that allows
to load and attach the bpf program via kprobe session.
the attachment to create kprobe multi session.

Also adding new program loader section that allows:
 SEC("kprobe.session/bpf_fentry_test*")

and loads/attaches kprobe program as kprobe session.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240430112830.1184228-5-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2024-04-30 13:28:27 +02:00 committed by Andrii Nakryiko
parent 5c919acef8
commit 2ca178f02b
3 changed files with 41 additions and 3 deletions
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1
tools/lib/bpf/bpf.c
View File

@ -766,6 +766,7 @@ int bpf_link_create(int prog_fd, int target_fd,
return libbpf_err(-EINVAL);
break;
case BPF_TRACE_KPROBE_MULTI:
case BPF_TRACE_KPROBE_SESSION:
attr.link_create.kprobe_multi.flags = OPTS_GET(opts, kprobe_multi.flags, 0);
attr.link_create.kprobe_multi.cnt = OPTS_GET(opts, kprobe_multi.cnt, 0);
attr.link_create.kprobe_multi.syms = ptr_to_u64(OPTS_GET(opts, kprobe_multi.syms, 0));

39
tools/lib/bpf/libbpf.c
View File

@ -9273,6 +9273,7 @@ static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_lin
static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_kprobe_session(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
@ -9289,6 +9290,7 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("uretprobe.s+", KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
SEC_DEF("kprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("kretprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
SEC_DEF("kprobe.session+", KPROBE, BPF_TRACE_KPROBE_SESSION, SEC_NONE, attach_kprobe_session),
SEC_DEF("uprobe.multi+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
SEC_DEF("uretprobe.multi+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
SEC_DEF("uprobe.multi.s+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
@ -11381,13 +11383,14 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
struct kprobe_multi_resolve res = {
.pattern = pattern,
};
enum bpf_attach_type attach_type;
struct bpf_link *link = NULL;
char errmsg[STRERR_BUFSIZE];
const unsigned long *addrs;
int err, link_fd, prog_fd;
bool retprobe, session;
const __u64 *cookies;
const char **syms;
bool retprobe;
size_t cnt;
if (!OPTS_VALID(opts, bpf_kprobe_multi_opts))
@ -11426,6 +11429,12 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
}
retprobe = OPTS_GET(opts, retprobe, false);
session = OPTS_GET(opts, session, false);
if (retprobe && session)
return libbpf_err_ptr(-EINVAL);
attach_type = session ? BPF_TRACE_KPROBE_SESSION : BPF_TRACE_KPROBE_MULTI;
lopts.kprobe_multi.syms = syms;
lopts.kprobe_multi.addrs = addrs;
@ -11440,7 +11449,7 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
}
link->detach = &bpf_link__detach_fd;
link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_KPROBE_MULTI, &lopts);
link_fd = bpf_link_create(prog_fd, 0, attach_type, &lopts);
if (link_fd < 0) {
err = -errno;
pr_warn("prog '%s': failed to attach: %s\n",
@ -11546,6 +11555,32 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
return libbpf_get_error(*link);
}
static int attach_kprobe_session(const struct bpf_program *prog, long cookie,
struct bpf_link **link)
{
LIBBPF_OPTS(bpf_kprobe_multi_opts, opts, .session = true);
const char *spec;
char *pattern;
int n;
*link = NULL;
/* no auto-attach for SEC("kprobe.session") */
if (strcmp(prog->sec_name, "kprobe.session") == 0)
return 0;
spec = prog->sec_name + sizeof("kprobe.session/") - 1;
n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
if (n < 1) {
pr_warn("kprobe session pattern is invalid: %s\n", pattern);
return -EINVAL;
}
*link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
free(pattern);
return *link ? 0 : -errno;
}
static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
{
char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;

4
tools/lib/bpf/libbpf.h
View File

@ -539,10 +539,12 @@ struct bpf_kprobe_multi_opts {
size_t cnt;
/* create return kprobes */
bool retprobe;
/* create session kprobes */
bool session;
size_t :0;
};
#define bpf_kprobe_multi_opts__last_field retprobe
#define bpf_kprobe_multi_opts__last_field session
LIBBPF_API struct bpf_link *
bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,