netdev - [PATCH bpf-next 5/6] libbpf: add support for supplying target to bpf_raw_tracepoint

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Message-ID: <159467114516.370286.16673271076079979202.stgit@toke.dk>
Date:   Mon, 13 Jul 2020 22:12:25 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH bpf-next 5/6] libbpf: add support for supplying target to
 bpf_raw_tracepoint_open()

From: Toke Høiland-Jørgensen <toke@...hat.com>

This adds support for supplying a target fd and btf ID for the
raw_tracepoint_open() BPF operation, using a new bpf_raw_tracepoint_opts
structure. This can be used for attaching freplace programs to multiple
destinations.

Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
 tools/lib/bpf/bpf.c      |   33 ++++++++++++++++++++++++++++++++-
 tools/lib/bpf/bpf.h      |   12 ++++++++++++
 tools/lib/bpf/libbpf.map |    1 +
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index a7329b671c41..6e7690d8ddfb 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -793,17 +793,48 @@ int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
 	return err;
 }
 
-int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+int bpf_raw_tracepoint_open_opts(const char *name, int prog_fd,
+				 struct bpf_raw_tracepoint_opts *opts)
 {
 	union bpf_attr attr;
+	size_t log_buf_sz;
+	__u32 log_level;
+	char *log_buf;
+
+	if (!OPTS_VALID(opts, bpf_raw_tracepoint_opts))
+		return -EINVAL;
+
+	log_buf = OPTS_GET(opts, log_buf, NULL);
+	log_buf_sz = OPTS_GET(opts, log_buf_sz, 0);
+	log_level = OPTS_GET(opts, log_level, 0);
+
+	if (!log_buf != !log_buf_sz || log_level > (4 | 2 | 1) ||
+	    (log_level && !log_buf))
+		return -EINVAL;
 
 	memset(&attr, 0, sizeof(attr));
 	attr.raw_tracepoint.name = ptr_to_u64(name);
 	attr.raw_tracepoint.prog_fd = prog_fd;
+	attr.raw_tracepoint.tgt_prog_fd = OPTS_GET(opts, tgt_prog_fd, 0);
+	attr.raw_tracepoint.tgt_btf_id = OPTS_GET(opts, tgt_btf_id, 0);
+
+	attr.raw_tracepoint.log_level = log_level;
+	if (log_level) {
+		attr.raw_tracepoint.log_buf = ptr_to_u64(log_buf);
+		attr.raw_tracepoint.log_size = log_buf_sz;
+	} else {
+		attr.raw_tracepoint.log_buf = ptr_to_u64(NULL);
+		attr.raw_tracepoint.log_size = 0;
+	}
 
 	return sys_bpf(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));
 }
 
+int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+{
+	return bpf_raw_tracepoint_open_opts(name, prog_fd, NULL);
+}
+
 int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
 		 bool do_log)
 {
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 1b6015b21ba8..b6b8ebb6ce65 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -227,7 +227,19 @@ LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
 LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type,
 			      __u32 query_flags, __u32 *attach_flags,
 			      __u32 *prog_ids, __u32 *prog_cnt);
+struct bpf_raw_tracepoint_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 log_level;
+	char *log_buf;
+	size_t log_buf_sz;
+	int tgt_prog_fd; /* target program to attach to */
+	__u32 tgt_btf_id; /* BTF ID of target function */
+};
+#define bpf_raw_tracepoint_opts__last_field tgt_btf_id
+
 LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);
+LIBBPF_API int bpf_raw_tracepoint_open_opts(const char *name, int prog_fd,
+					    struct bpf_raw_tracepoint_opts *opts);
 LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,
 			    __u32 log_buf_size, bool do_log);
 LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 6544d2cd1ed6..f726805f5ec8 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -288,4 +288,5 @@ LIBBPF_0.1.0 {
 		bpf_map__value_size;
 		bpf_program__autoload;
 		bpf_program__set_autoload;
+		bpf_raw_tracepoint_open_opts;
 } LIBBPF_0.0.9;