libbpf: Add bpf_program__attach_kprobe_multi_opts function

Adding bpf_program__attach_kprobe_multi_opts function for attaching
kprobe program to multiple functions.

  struct bpf_link *
  bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
                                        const char *pattern,
                                        const struct bpf_kprobe_multi_opts *opts);

User can specify functions to attach with 'pattern' argument that
allows wildcards (*?' supported) or provide symbols or addresses
directly through opts argument. These 3 options are mutually
exclusive.

When using symbols or addresses, user can also provide cookie value
for each symbol/address that can be retrieved later in bpf program
with bpf_get_attach_cookie helper.

  struct bpf_kprobe_multi_opts {
          size_t sz;
          const char **syms;
          const unsigned long *addrs;
          const __u64 *cookies;
          size_t cnt;
          bool retprobe;
          size_t :0;
  };

Symbols, addresses and cookies are provided through opts object
(syms/addrs/cookies) as array pointers with specified count (cnt).

Each cookie value is paired with provided function address or symbol
with the same array index.

The program can be also attached as return probe if 'retprobe' is set.

For quick usage with NULL opts argument, like:

  bpf_program__attach_kprobe_multi_opts(prog, "ksys_*", NULL)

the 'prog' will be attached as kprobe to 'ksys_*' functions.

Also adding new program sections for automatic attachment:

  kprobe.multi/<symbol_pattern>
  kretprobe.multi/<symbol_pattern>

The symbol_pattern is used as 'pattern' argument in
bpf_program__attach_kprobe_multi_opts function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220316122419.933957-10-jolsa@kernel.org

1 files changed, 23 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index c1b0c2ef14d8..d5239fb4abdc 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -425,6 +425,29 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
                                 const char *func_name,
                                 const struct bpf_kprobe_opts *opts);
 
+struct bpf_kprobe_multi_opts {
+	/* size of this struct, for forward/backward compatibility */
+	size_t sz;
+	/* array of function symbols to attach */
+	const char **syms;
+	/* array of function addresses to attach */
+	const unsigned long *addrs;
+	/* array of user-provided values fetchable through bpf_get_attach_cookie */
+	const __u64 *cookies;
+	/* number of elements in syms/addrs/cookies arrays */
+	size_t cnt;
+	/* create return kprobes */
+	bool retprobe;
+	size_t :0;
+};
+
+#define bpf_kprobe_multi_opts__last_field retprobe
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
+				      const char *pattern,
+				      const struct bpf_kprobe_multi_opts *opts);
+
 struct bpf_uprobe_opts {
 	/* size of this struct, for forward/backward compatiblity */
 	size_t sz;