libbpf: Add BPF_PROG_BIND_MAP syscall and use it on .rodata section (5d23328d) · Commits · 戴 / test

tools/lib/bpf/bpf.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -872,3 +872,19 @@ int bpf_enable_stats(enum bpf_stats_type type)

		return sys_bpf(BPF_ENABLE_STATS, &attr, sizeof(attr));
		}

		int bpf_prog_bind_map(int prog_fd, int map_fd,
		const struct bpf_prog_bind_opts *opts)
		{
		union bpf_attr attr;

		if (!OPTS_VALID(opts, bpf_prog_bind_opts))
		return -EINVAL;

		memset(&attr, 0, sizeof(attr));
		attr.prog_bind_map.prog_fd = prog_fd;
		attr.prog_bind_map.map_fd = map_fd;
		attr.prog_bind_map.flags = OPTS_GET(opts, flags, 0);

		return sys_bpf(BPF_PROG_BIND_MAP, &attr, sizeof(attr));
		}

tools/lib/bpf/bpf.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -243,6 +243,14 @@ LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
		enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */
		LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type);

		struct bpf_prog_bind_opts {
		size_t sz; /* size of this struct for forward/backward compatibility */
		__u32 flags;
		};
		#define bpf_prog_bind_opts__last_field flags

		LIBBPF_API int bpf_prog_bind_map(int prog_fd, int map_fd,
		const struct bpf_prog_bind_opts *opts);
		#ifdef __cplusplus
		} /* extern "C" */
		#endif

tools/lib/bpf/libbpf.c

+69 −0

Original line number	Diff line number	Diff line
		@@ -174,6 +174,8 @@ enum kern_feature_id {
		FEAT_EXP_ATTACH_TYPE,
		/* bpf_probe_read_{kernel,user}[_str] helpers */
		FEAT_PROBE_READ_KERN,
		/* BPF_PROG_BIND_MAP is supported */
		FEAT_PROG_BIND_MAP,
		__FEAT_CNT,
		};

		@@ -409,6 +411,7 @@ struct bpf_object {
		struct extern_desc *externs;
		int nr_extern;
		int kconfig_map_idx;
		int rodata_map_idx;

		bool loaded;
		bool has_subcalls;
		@@ -1070,6 +1073,7 @@ static struct bpf_object bpf_object__new(const char path,
		obj->efile.bss_shndx = -1;
		obj->efile.st_ops_shndx = -1;
		obj->kconfig_map_idx = -1;
		obj->rodata_map_idx = -1;

		obj->kern_version = get_kernel_version();
		obj->loaded = false;
		@@ -1428,6 +1432,8 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
		obj->efile.rodata->d_size);
		if (err)
		return err;

		obj->rodata_map_idx = obj->nr_maps - 1;
		}
		if (obj->efile.bss_shndx >= 0) {
		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
		@@ -3894,6 +3900,52 @@ static int probe_kern_probe_read_kernel(void)
		return probe_fd(bpf_load_program_xattr(&attr, NULL, 0));
		}

		static int probe_prog_bind_map(void)
		{
		struct bpf_load_program_attr prg_attr;
		struct bpf_create_map_attr map_attr;
		char *cp, errmsg[STRERR_BUFSIZE];
		struct bpf_insn insns[] = {
		BPF_MOV64_IMM(BPF_REG_0, 0),
		BPF_EXIT_INSN(),
		};
		int ret, map, prog;

		memset(&map_attr, 0, sizeof(map_attr));
		map_attr.map_type = BPF_MAP_TYPE_ARRAY;
		map_attr.key_size = sizeof(int);
		map_attr.value_size = 32;
		map_attr.max_entries = 1;

		map = bpf_create_map_xattr(&map_attr);
		if (map < 0) {
		ret = -errno;
		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
		__func__, cp, -ret);
		return ret;
		}

		memset(&prg_attr, 0, sizeof(prg_attr));
		prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
		prg_attr.insns = insns;
		prg_attr.insns_cnt = ARRAY_SIZE(insns);
		prg_attr.license = "GPL";

		prog = bpf_load_program_xattr(&prg_attr, NULL, 0);
		if (prog < 0) {
		close(map);
		return 0;
		}

		ret = bpf_prog_bind_map(prog, map, NULL);

		close(map);
		close(prog);

		return ret >= 0;
		}

		enum kern_feature_result {
		FEAT_UNKNOWN = 0,
		FEAT_SUPPORTED = 1,
		@@ -3934,6 +3986,9 @@ static struct kern_feature_desc {
		},
		[FEAT_PROBE_READ_KERN] = {
		"bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
		},
		[FEAT_PROG_BIND_MAP] = {
		"BPF_PROG_BIND_MAP support", probe_prog_bind_map,
		}
		};

		@@ -6468,6 +6523,20 @@ retry_load:
		if (ret >= 0) {
		if (log_buf && load_attr.log_level)
		pr_debug("verifier log:\n%s", log_buf);

		if (prog->obj->rodata_map_idx >= 0 &&
		kernel_supports(FEAT_PROG_BIND_MAP)) {
		struct bpf_map *rodata_map =
		&prog->obj->maps[prog->obj->rodata_map_idx];

		if (bpf_prog_bind_map(ret, bpf_map__fd(rodata_map), NULL)) {
		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
		pr_warn("prog '%s': failed to bind .rodata map: %s\n",
		prog->name, cp);
		/* Don't fail hard if can't bind rodata. */
		}
		}

		*pfd = ret;
		ret = 0;
		goto out;

tools/lib/bpf/libbpf.map

+1 −0

Original line number	Diff line number	Diff line
		@@ -302,6 +302,7 @@ LIBBPF_0.1.0 {

		LIBBPF_0.2.0 {
		global:
		bpf_prog_bind_map;
		bpf_program__section_name;
		perf_buffer__buffer_cnt;
		perf_buffer__buffer_fd;

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