[PATCH 5/8] libbpf: Add support to attach multiple [ku]probes

[Jiri Olsa]

Adding support to attach multiple [ku]probes.

Extending both bpf_kprobe_opts and bpf_uprobe_opts structs
with config values to define multiple probes within single
bpf_program__attach_[ku]probe_opts call.

For mutiple probes in bpf_program__attach_kprobe_opts function
the 'func_name' argument is ignored and probes are defined in
bpf_kprobe_opts struct with:

  struct {
          /* probes count */
          __u32 cnt;
          /* function names array */
          char **funcs;
          /* address/offset values array */
          union {
                  __u64 *addrs;
                  __u64 *offs;
          };
  } multi;

For mutiple probes in bpf_program__attach_uprobe_opts function
both 'binary_path' and 'func_offset' arguments are ignored and
probes are defined in bpf_kprobe_opts struct with:

  /* multi uprobe values */
  struct {
          /* probes count */
          __u32 cnt;
          /* paths names array */
          const char **paths;
          /* offsets values array */
          __u64 *offs;
  } multi;

The multiple probes attachment is enabled when multi.cnt != 0.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/include/uapi/linux/perf_event.h |  1 +
 tools/lib/bpf/libbpf.c                | 30 +++++++++++++++++++++++++--
 tools/lib/bpf/libbpf.h                | 25 ++++++++++++++++++++--
 3 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index bd8860eeb291..eea80709d1ed 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -414,6 +414,7 @@ struct perf_event_attr {
 	union {
 		__u32		wakeup_events;	  /* wakeup every n events */
 		__u32		wakeup_watermark; /* bytes before wakeup   */
+		__u32		probe_cnt;	  /* number of [k,u] probes */
 	};
 
 	__u32			bp_type;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 34219a0c39a7..b570e93de735 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9631,6 +9631,11 @@ struct perf_event_open_args {
 	uint64_t offset;
 	int pid;
 	size_t ref_ctr_off;
+	struct {
+		__u32 probe_cnt;
+		__u64 config1;
+		__u64 config2;
+	} multi;
 };
 
 static int perf_event_open_probe(bool uprobe, struct perf_event_open_args *args)
@@ -9667,8 +9672,15 @@ static int perf_event_open_probe(bool uprobe, struct perf_event_open_args *args)
 	attr.size = sizeof(attr);
 	attr.type = type;
 	attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
-	attr.config1 = ptr_to_u64(args->name); /* kprobe_func or uprobe_path */
-	attr.config2 = args->offset;		 /* kprobe_addr or probe_offset */
+
+	if (args->multi.probe_cnt) {
+		attr.probe_cnt = args->multi.probe_cnt;
+		attr.config1 = args->multi.config1;
+		attr.config2 = args->multi.config2;
+	} else {
+		attr.config1 = ptr_to_u64(args->name); /* kprobe_func or uprobe_path */
+		attr.config2 = args->offset;	       /* kprobe_addr or probe_offset */
+	}
 
 	/* pid filter is meaningful only for uprobes */
 	pfd = syscall(__NR_perf_event_open, &attr,
@@ -9807,7 +9819,14 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
 			.pid = -1,
 			.ref_ctr_off = 0,
 		};
+		__u32 probe_cnt = OPTS_GET(opts, multi.cnt, false);
 
+		if (probe_cnt) {
+			args.multi.probe_cnt = probe_cnt;
+			args.multi.config1 = ptr_to_u64(OPTS_GET(opts, multi.funcs, false));
+			/* multi.addrs and multi.offs share the same array */
+			args.multi.config2 = ptr_to_u64(OPTS_GET(opts, multi.addrs, false));
+		}
 		pfd = perf_event_open_probe(false /* uprobe */, &args);
 	} else {
 		char probe_name[256];
@@ -10006,6 +10025,13 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 			.pid = pid,
 			.ref_ctr_off = ref_ctr_off,
 		};
+		__u32 probe_cnt = OPTS_GET(opts, multi.cnt, false);
+
+		if (probe_cnt) {
+			args.multi.probe_cnt = probe_cnt;
+			args.multi.config1 = ptr_to_u64(OPTS_GET(opts, multi.paths, false));
+			args.multi.config2 = ptr_to_u64(OPTS_GET(opts, multi.offs, false));
+		}
 
 		pfd = perf_event_open_probe(true /* uprobe */, &args);
 	} else {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index d02139fec4ac..ae072882b5dd 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -321,9 +321,21 @@ struct bpf_kprobe_opts {
 	size_t offset;
 	/* kprobe is return probe */
 	bool retprobe;
+	/* multi kprobe values */
+	struct {
+		/* probes count */
+		__u32 cnt;
+		/* function names array */
+		char **funcs;
+		/* address/offset values array */
+		union {
+			__u64 *addrs;
+			__u64 *offs;
+		};
+	} multi;
 	size_t :0;
 };
-#define bpf_kprobe_opts__last_field retprobe
+#define bpf_kprobe_opts__last_field multi.addrs
 
 LIBBPF_API struct bpf_link *
 bpf_program__attach_kprobe(const struct bpf_program *prog, bool retprobe,
@@ -344,9 +356,18 @@ struct bpf_uprobe_opts {
 	__u64 bpf_cookie;
 	/* uprobe is return probe, invoked at function return time */
 	bool retprobe;
+	/* multi uprobe values */
+	struct {
+		/* probes count */
+		__u32 cnt;
+		/* paths names array */
+		const char **paths;
+		/* offsets values array */
+		__u64 *offs;
+	} multi;
 	size_t :0;
 };
-#define bpf_uprobe_opts__last_field retprobe
+#define bpf_uprobe_opts__last_field multi.offs
 
 LIBBPF_API struct bpf_link *
 bpf_program__attach_uprobe(const struct bpf_program *prog, bool retprobe,
-- 
2.33.1