libbpf: add kprobe/uprobe attach API (b2650027) · Commits · 戴 / test

tools/lib/bpf/libbpf.c

+169 −0

Original line number	Diff line number	Diff line
		@@ -4021,6 +4021,175 @@ struct bpf_link bpf_program__attach_perf_event(struct bpf_program prog,
		return (struct bpf_link *)link;
		}

		/*
		* 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
		* negative, the result might be indistinguishable from error
		*/
		static int parse_uint_from_file(const char file, const char fmt)
		{
		char buf[STRERR_BUFSIZE];
		int err, ret;
		FILE *f;

		f = fopen(file, "r");
		if (!f) {
		err = -errno;
		pr_debug("failed to open '%s': %s\n", file,
		libbpf_strerror_r(err, buf, sizeof(buf)));
		return err;
		}
		err = fscanf(f, fmt, &ret);
		if (err != 1) {
		err = err == EOF ? -EIO : -errno;
		pr_debug("failed to parse '%s': %s\n", file,
		libbpf_strerror_r(err, buf, sizeof(buf)));
		fclose(f);
		return err;
		}
		fclose(f);
		return ret;
		}

		static int determine_kprobe_perf_type(void)
		{
		const char *file = "/sys/bus/event_source/devices/kprobe/type";

		return parse_uint_from_file(file, "%d\n");
		}

		static int determine_uprobe_perf_type(void)
		{
		const char *file = "/sys/bus/event_source/devices/uprobe/type";

		return parse_uint_from_file(file, "%d\n");
		}

		static int determine_kprobe_retprobe_bit(void)
		{
		const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";

		return parse_uint_from_file(file, "config:%d\n");
		}

		static int determine_uprobe_retprobe_bit(void)
		{
		const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";

		return parse_uint_from_file(file, "config:%d\n");
		}

		static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
		uint64_t offset, int pid)
		{
		struct perf_event_attr attr = {};
		char errmsg[STRERR_BUFSIZE];
		int type, pfd, err;

		type = uprobe ? determine_uprobe_perf_type()
		: determine_kprobe_perf_type();
		if (type < 0) {
		pr_warning("failed to determine %s perf type: %s\n",
		uprobe ? "uprobe" : "kprobe",
		libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
		return type;
		}
		if (retprobe) {
		int bit = uprobe ? determine_uprobe_retprobe_bit()
		: determine_kprobe_retprobe_bit();

		if (bit < 0) {
		pr_warning("failed to determine %s retprobe bit: %s\n",
		uprobe ? "uprobe" : "kprobe",
		libbpf_strerror_r(bit, errmsg,
		sizeof(errmsg)));
		return bit;
		}
		attr.config \|= 1 << bit;
		}
		attr.size = sizeof(attr);
		attr.type = type;
		attr.config1 = (uint64_t)(void )name; / kprobe_func or uprobe_path */
		attr.config2 = offset; /* kprobe_addr or probe_offset */

		/* pid filter is meaningful only for uprobes */
		pfd = syscall(__NR_perf_event_open, &attr,
		pid < 0 ? -1 : pid /* pid */,
		pid == -1 ? 0 : -1 /* cpu */,
		-1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
		if (pfd < 0) {
		err = -errno;
		pr_warning("%s perf_event_open() failed: %s\n",
		uprobe ? "uprobe" : "kprobe",
		libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
		return err;
		}
		return pfd;
		}

		struct bpf_link bpf_program__attach_kprobe(struct bpf_program prog,
		bool retprobe,
		const char *func_name)
		{
		char errmsg[STRERR_BUFSIZE];
		struct bpf_link *link;
		int pfd, err;

		pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
		0 /* offset /, -1 / pid */);
		if (pfd < 0) {
		pr_warning("program '%s': failed to create %s '%s' perf event: %s\n",
		bpf_program__title(prog, false),
		retprobe ? "kretprobe" : "kprobe", func_name,
		libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
		return ERR_PTR(pfd);
		}
		link = bpf_program__attach_perf_event(prog, pfd);
		if (IS_ERR(link)) {
		close(pfd);
		err = PTR_ERR(link);
		pr_warning("program '%s': failed to attach to %s '%s': %s\n",
		bpf_program__title(prog, false),
		retprobe ? "kretprobe" : "kprobe", func_name,
		libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
		return link;
		}
		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)
		{
		char errmsg[STRERR_BUFSIZE];
		struct bpf_link *link;
		int pfd, err;

		pfd = perf_event_open_probe(true /* uprobe */, retprobe,
		binary_path, func_offset, pid);
		if (pfd < 0) {
		pr_warning("program '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
		bpf_program__title(prog, false),
		retprobe ? "uretprobe" : "uprobe",
		binary_path, func_offset,
		libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
		return ERR_PTR(pfd);
		}
		link = bpf_program__attach_perf_event(prog, pfd);
		if (IS_ERR(link)) {
		close(pfd);
		err = PTR_ERR(link);
		pr_warning("program '%s': failed to attach to %s '%s:0x%zx': %s\n",
		bpf_program__title(prog, false),
		retprobe ? "uretprobe" : "uprobe",
		binary_path, func_offset,
		libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
		return link;
		}
		return link;
		}

		enum bpf_perf_event_ret
		bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
		void *copy_mem, size_t copy_size,

tools/lib/bpf/libbpf.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -171,6 +171,13 @@ LIBBPF_API int bpf_link__destroy(struct bpf_link *link);

		LIBBPF_API struct bpf_link *
		bpf_program__attach_perf_event(struct bpf_program *prog, int pfd);
		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_uprobe(struct bpf_program *prog, bool retprobe,
		pid_t pid, const char *binary_path,
		size_t func_offset);

		struct bpf_insn;

tools/lib/bpf/libbpf.map

+2 −0

Original line number	Diff line number	Diff line
		@@ -169,7 +169,9 @@ LIBBPF_0.0.4 {
		global:
		bpf_link__destroy;
		bpf_object__load_xattr;
		bpf_program__attach_kprobe;
		bpf_program__attach_perf_event;
		bpf_program__attach_uprobe;
		btf_dump__dump_type;
		btf_dump__free;
		btf_dump__new;

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