Commit 2ca178f0 authored by Jiri Olsa's avatar Jiri Olsa Committed by Andrii Nakryiko
Browse files

libbpf: Add support for kprobe session attach 



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: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240430112830.1184228-5-jolsa@kernel.org
parent 5c919ace

tools/lib/bpf/bpf.c

+1 −0
Original line number Diff line number Diff line
@@ -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));

tools/lib/bpf/libbpf.c

+37 −2
Original line number Diff line number Diff line
@@ -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;

tools/lib/bpf/libbpf.h

+3 −1
Original line number Diff line number Diff line
@@ -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,