diff mbox series

[v2,bpf-next,11/14] libbpf: add user_ctx to perf_event, kprobe, uprobe, and tp attach APIs

Message ID 20210726161211.925206-12-andrii@kernel.org (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series BPF perf link and user-provided context value | expand

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netdev/cc_maintainers warning 6 maintainers not CCed: netdev@vger.kernel.org yhs@fb.com kpsingh@kernel.org kafai@fb.com john.fastabend@gmail.com songliubraving@fb.com
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netdev/checkpatch fail CHECK: Alignment should match open parenthesis CHECK: Please use a blank line after function/struct/union/enum declarations ERROR: code indent should use tabs where possible ERROR: space prohibited before that ':' (ctx:WxV) WARNING: 'compatiblity' may be misspelled - perhaps 'compatibility'? WARNING: line length of 82 exceeds 80 columns WARNING: line length of 84 exceeds 80 columns WARNING: line length of 85 exceeds 80 columns WARNING: line length of 87 exceeds 80 columns WARNING: line length of 91 exceeds 80 columns WARNING: line length of 92 exceeds 80 columns WARNING: line length of 96 exceeds 80 columns WARNING: please, no spaces at the start of a line
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Commit Message

Andrii Nakryiko July 26, 2021, 4:12 p.m. UTC 
Wire through user_ctx for all attach APIs that use perf_event_open under the
hood:
  - for kprobes, extend existing bpf_kprobe_opts with user_ctx field;
  - for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
    pass user_ctx through opts.

For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
user_ctx is not supported either, return error and log warning for user.

Cc: Rafael David Tinoco <rafaeldtinoco@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c   | 78 +++++++++++++++++++++++++++++++++-------
 tools/lib/bpf/libbpf.h   | 71 +++++++++++++++++++++++++++++-------
 tools/lib/bpf/libbpf.map |  3 ++
 3 files changed, 127 insertions(+), 25 deletions(-)

Comments

Rafael David Tinoco July 30, 2021, 1:11 a.m. UTC | #1 
On Mon, Jul 26, 2021, at 13:12, Andrii Nakryiko wrote:
> Wire through user_ctx for all attach APIs that use perf_event_open under the
> hood:
>   - for kprobes, extend existing bpf_kprobe_opts with user_ctx field;
>   - for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
>     pass user_ctx through opts.
> 
> For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
> user_ctx is not supported either, return error and log warning for user.
> 
> Cc: Rafael David Tinoco <rafaeldtinoco@gmail.com>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

I think this one is fuzzy in v2. Checking them now for my purposes. Thanks for CC'ing.
diff mbox series

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 682e7aa8f90b..5836d3627ba6 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10274,12 +10274,16 @@  static void bpf_link_perf_dealloc(struct bpf_link *link)
 	free(perf_link);
 }
 
-struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
+struct bpf_link *bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,
+						     const struct bpf_perf_event_opts *opts)
 {
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link_perf *link;
 	int prog_fd, link_fd = -1, err;
 
+	if (!OPTS_VALID(opts, bpf_perf_event_opts))
+		return libbpf_err_ptr(-EINVAL);
+
 	if (pfd < 0) {
 		pr_warn("prog '%s': invalid perf event FD %d\n",
 			prog->name, pfd);
@@ -10300,7 +10304,10 @@  struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf
 	link->perf_event_fd = pfd;
 
 	if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {
-		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, NULL);
+		DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
+			.perf_event.user_ctx = OPTS_GET(opts, user_ctx, 0));
+
+		link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
 		if (link_fd < 0) {
 			err = -errno;
 			pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
@@ -10310,6 +10317,12 @@  struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf
 		}
 		link->link.fd = link_fd;
 	} else {
+		if (OPTS_GET(opts, user_ctx, 0)) {
+			pr_warn("prog '%s': user context value is not supported\n", prog->name);
+			err = -EOPNOTSUPP;
+			goto err_out;
+		}
+
 		if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
 			err = -errno;
 			pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
@@ -10336,6 +10349,11 @@  struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf
 	return libbpf_err_ptr(err);
 }
 
+struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
+{
+	return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
+}
+
 /*
  * this function is expected to parse integer in the range of [0, 2^31-1] from
  * given file using scanf format string fmt. If actual parsed value is
@@ -10444,8 +10462,9 @@  static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
 struct bpf_link *
 bpf_program__attach_kprobe_opts(struct bpf_program *prog,
 				const char *func_name,
-				struct bpf_kprobe_opts *opts)
+				const struct bpf_kprobe_opts *opts)
 {
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
 	unsigned long offset;
@@ -10457,6 +10476,7 @@  bpf_program__attach_kprobe_opts(struct bpf_program *prog,
 
 	retprobe = OPTS_GET(opts, retprobe, false);
 	offset = OPTS_GET(opts, offset, 0);
+	pe_opts.user_ctx = OPTS_GET(opts, user_ctx, 0);
 
 	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
 				    offset, -1 /* pid */);
@@ -10466,7 +10486,7 @@  bpf_program__attach_kprobe_opts(struct bpf_program *prog,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return libbpf_err_ptr(pfd);
 	}
-	link = bpf_program__attach_perf_event(prog, pfd);
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
 	err = libbpf_get_error(link);
 	if (err) {
 		close(pfd);
@@ -10521,14 +10541,22 @@  static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
 	return link;
 }
 
-struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
-					    bool retprobe, pid_t pid,
-					    const char *binary_path,
-					    size_t func_offset)
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe_opts(struct bpf_program *prog, pid_t pid,
+				const char *binary_path, size_t func_offset,
+				const struct bpf_uprobe_opts *opts)
 {
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
 	int pfd, err;
+	bool retprobe;
+
+	if (!OPTS_VALID(opts, bpf_uprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+	pe_opts.user_ctx = OPTS_GET(opts, user_ctx, 0);
 
 	pfd = perf_event_open_probe(true /* uprobe */, retprobe,
 				    binary_path, func_offset, pid);
@@ -10539,7 +10567,7 @@  struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return libbpf_err_ptr(pfd);
 	}
-	link = bpf_program__attach_perf_event(prog, pfd);
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
 	err = libbpf_get_error(link);
 	if (err) {
 		close(pfd);
@@ -10552,6 +10580,16 @@  struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
 	return link;
 }
 
+struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
+					    bool retprobe, pid_t pid,
+					    const char *binary_path,
+					    size_t func_offset)
+{
+	DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
+
+	return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
+}
+
 static int determine_tracepoint_id(const char *tp_category,
 				   const char *tp_name)
 {
@@ -10602,14 +10640,21 @@  static int perf_event_open_tracepoint(const char *tp_category,
 	return pfd;
 }
 
-struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
-						const char *tp_category,
-						const char *tp_name)
+struct bpf_link *bpf_program__attach_tracepoint_opts(struct bpf_program *prog,
+						     const char *tp_category,
+						     const char *tp_name,
+						     const struct bpf_tracepoint_opts *opts)
 {
+	DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
 	int pfd, err;
 
+	if (!OPTS_VALID(opts, bpf_tracepoint_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	pe_opts.user_ctx = OPTS_GET(opts, user_ctx, 0);
+
 	pfd = perf_event_open_tracepoint(tp_category, tp_name);
 	if (pfd < 0) {
 		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
@@ -10617,7 +10662,7 @@  struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return libbpf_err_ptr(pfd);
 	}
-	link = bpf_program__attach_perf_event(prog, pfd);
+	link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
 	err = libbpf_get_error(link);
 	if (err) {
 		close(pfd);
@@ -10629,6 +10674,13 @@  struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
 	return link;
 }
 
+struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
+						const char *tp_category,
+						const char *tp_name)
+{
+	return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
+}
+
 static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,
 				  struct bpf_program *prog)
 {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 1271d99bb7aa..85d336bcb510 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -104,17 +104,6 @@  struct bpf_object_open_opts {
 };
 #define bpf_object_open_opts__last_field btf_custom_path
 
-struct bpf_kprobe_opts {
-	/* size of this struct, for forward/backward compatiblity */
-	size_t sz;
-	/* function's offset to install kprobe to */
-	unsigned long offset;
-	/* kprobe is return probe */
-	bool retprobe;
-	size_t :0;
-};
-#define bpf_kprobe_opts__last_field retprobe
-
 LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
 LIBBPF_API struct bpf_object *
 bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts);
@@ -255,24 +244,82 @@  LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
 
 LIBBPF_API struct bpf_link *
 bpf_program__attach(struct bpf_program *prog);
+
+struct bpf_perf_event_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_user_ctx() */
+	__u64 user_ctx;
+};
+#define bpf_perf_event_opts__last_field user_ctx
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_perf_event(struct bpf_program *prog, int pfd);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,
+				    const struct bpf_perf_event_opts *opts);
+
+struct bpf_kprobe_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_user_ctx() */
+	__u64 user_ctx;
+	/* function's offset to install kprobe to */
+	unsigned long offset;
+	/* kprobe is return probe */
+	bool retprobe;
+	size_t :0;
+};
+#define bpf_kprobe_opts__last_field retprobe
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,
 			   const char *func_name);
 LIBBPF_API struct bpf_link *
 bpf_program__attach_kprobe_opts(struct bpf_program *prog,
                                 const char *func_name,
-                                struct bpf_kprobe_opts *opts);
+                                const struct bpf_kprobe_opts *opts);
+
+struct bpf_uprobe_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_user_ctx() */
+	__u64 user_ctx;
+	/* uprobe is return probe, invoked at function return time */
+	bool retprobe;
+	size_t :0;
+};
+#define bpf_uprobe_opts__last_field retprobe
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe,
 			   pid_t pid, const char *binary_path,
 			   size_t func_offset);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe_opts(struct bpf_program *prog, pid_t pid,
+				const char *binary_path, size_t func_offset,
+				const struct bpf_uprobe_opts *opts);
+
+struct bpf_tracepoint_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* custom user-provided value fetchable through bpf_get_user_ctx() */
+	__u64 user_ctx;
+};
+#define bpf_tracepoint_opts__last_field user_ctx
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_tracepoint(struct bpf_program *prog,
 			       const char *tp_category,
 			       const char *tp_name);
 LIBBPF_API struct bpf_link *
+bpf_program__attach_tracepoint_opts(struct bpf_program *prog,
+				    const char *tp_category,
+				    const char *tp_name,
+				    const struct bpf_tracepoint_opts *opts);
+
+LIBBPF_API struct bpf_link *
 bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
 				   const char *tp_name);
 LIBBPF_API struct bpf_link *
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index c240d488eb5e..a156f012e23d 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -374,6 +374,9 @@  LIBBPF_0.5.0 {
 		bpf_map__pin_path;
 		bpf_map_lookup_and_delete_elem_flags;
 		bpf_program__attach_kprobe_opts;
+		bpf_program__attach_perf_event_opts;
+		bpf_program__attach_tracepoint_opts;
+		bpf_program__attach_uprobe_opts;
 		bpf_object__gen_loader;
 		btf_dump__dump_type_data;
 		libbpf_set_strict_mode;