1 files changed, 596 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/struct_ops.c b/tools/bpf/bpftool/struct_ops.c
new file mode 100644
index 000000000000..2a7befbd11ad
--- /dev/null
+++ b/tools/bpf/bpftool/struct_ops.c
@@ -0,0 +1,596 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (C) 2020 Facebook */
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <linux/err.h>
+
+#include <bpf/bpf.h>
+#include <bpf/btf.h>
+#include <bpf/libbpf.h>
+
+#include "json_writer.h"
+#include "main.h"
+
+#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
+
+static const struct btf_type *map_info_type;
+static __u32 map_info_alloc_len;
+static struct btf *btf_vmlinux;
+static __s32 map_info_type_id;
+
+struct res {
+	unsigned int nr_maps;
+	unsigned int nr_errs;
+};
+
+static const struct btf *get_btf_vmlinux(void)
+{
+	if (btf_vmlinux)
+		return btf_vmlinux;
+
+	btf_vmlinux = libbpf_find_kernel_btf();
+	if (IS_ERR(btf_vmlinux))
+		p_err("struct_ops requires kernel CONFIG_DEBUG_INFO_BTF=y");
+
+	return btf_vmlinux;
+}
+
+static const char *get_kern_struct_ops_name(const struct bpf_map_info *info)
+{
+	const struct btf *kern_btf;
+	const struct btf_type *t;
+	const char *st_ops_name;
+
+	kern_btf = get_btf_vmlinux();
+	if (IS_ERR(kern_btf))
+		return "<btf_vmlinux_not_found>";
+
+	t = btf__type_by_id(kern_btf, info->btf_vmlinux_value_type_id);
+	st_ops_name = btf__name_by_offset(kern_btf, t->name_off);
+	st_ops_name += strlen(STRUCT_OPS_VALUE_PREFIX);
+
+	return st_ops_name;
+}
+
+static __s32 get_map_info_type_id(void)
+{
+	const struct btf *kern_btf;
+
+	if (map_info_type_id)
+		return map_info_type_id;
+
+	kern_btf = get_btf_vmlinux();
+	if (IS_ERR(kern_btf)) {
+		map_info_type_id = PTR_ERR(kern_btf);
+		return map_info_type_id;
+	}
+
+	map_info_type_id = btf__find_by_name_kind(kern_btf, "bpf_map_info",
+						  BTF_KIND_STRUCT);
+	if (map_info_type_id < 0) {
+		p_err("can't find bpf_map_info from btf_vmlinux");
+		return map_info_type_id;
+	}
+	map_info_type = btf__type_by_id(kern_btf, map_info_type_id);
+
+	/* Ensure map_info_alloc() has at least what the bpftool needs */
+	map_info_alloc_len = map_info_type->size;
+	if (map_info_alloc_len < sizeof(struct bpf_map_info))
+		map_info_alloc_len = sizeof(struct bpf_map_info);
+
+	return map_info_type_id;
+}
+
+/* If the subcmd needs to print out the bpf_map_info,
+ * it should always call map_info_alloc to allocate
+ * a bpf_map_info object instead of allocating it
+ * on the stack.
+ *
+ * map_info_alloc() will take the running kernel's btf
+ * into account.  i.e. it will consider the
+ * sizeof(struct bpf_map_info) of the running kernel.
+ *
+ * It will enable the "struct_ops" cmd to print the latest
+ * "struct bpf_map_info".
+ *
+ * [ Recall that "struct_ops" requires the kernel's btf to
+ *   be available ]
+ */
+static struct bpf_map_info *map_info_alloc(__u32 *alloc_len)
+{
+	struct bpf_map_info *info;
+
+	if (get_map_info_type_id() < 0)
+		return NULL;
+
+	info = calloc(1, map_info_alloc_len);
+	if (!info)
+		p_err("mem alloc failed");
+	else
+		*alloc_len = map_info_alloc_len;
+
+	return info;
+}
+
+/* It iterates all struct_ops maps of the system.
+ * It returns the fd in "*res_fd" and map_info in "*info".
+ * In the very first iteration, info->id should be 0.
+ * An optional map "*name" filter can be specified.
+ * The filter can be made more flexible in the future.
+ * e.g. filter by kernel-struct-ops-name, regex-name, glob-name, ...etc.
+ *
+ * Return value:
+ *     1: A struct_ops map found.  It is returned in "*res_fd" and "*info".
+ *	  The caller can continue to call get_next in the future.
+ *     0: No struct_ops map is returned.
+ *        All struct_ops map has been found.
+ *    -1: Error and the caller should abort the iteration.
+ */
+static int get_next_struct_ops_map(const char *name, int *res_fd,
+				   struct bpf_map_info *info, __u32 info_len)
+{
+	__u32 id = info->id;
+	int err, fd;
+
+	while (true) {
+		err = bpf_map_get_next_id(id, &id);
+		if (err) {
+			if (errno == ENOENT)
+				return 0;
+			p_err("can't get next map: %s", strerror(errno));
+			return -1;
+		}
+
+		fd = bpf_map_get_fd_by_id(id);
+		if (fd < 0) {
+			if (errno == ENOENT)
+				continue;
+			p_err("can't get map by id (%u): %s",
+			      id, strerror(errno));
+			return -1;
+		}
+
+		err = bpf_obj_get_info_by_fd(fd, info, &info_len);
+		if (err) {
+			p_err("can't get map info: %s", strerror(errno));
+			close(fd);
+			return -1;
+		}
+
+		if (info->type == BPF_MAP_TYPE_STRUCT_OPS &&
+		    (!name || !strcmp(name, info->name))) {
+			*res_fd = fd;
+			return 1;
+		}
+		close(fd);
+	}
+}
+
+static int cmd_retval(const struct res *res, bool must_have_one_map)
+{
+	if (res->nr_errs || (!res->nr_maps && must_have_one_map))
+		return -1;
+
+	return 0;
+}
+
+/* "data" is the work_func private storage */
+typedef int (*work_func)(int fd, const struct bpf_map_info *info, void *data,
+			 struct json_writer *wtr);
+
+/* Find all struct_ops map in the system.
+ * Filter out by "name" (if specified).
+ * Then call "func(fd, info, data, wtr)" on each struct_ops map found.
+ */
+static struct res do_search(const char *name, work_func func, void *data,
+			    struct json_writer *wtr)
+{
+	struct bpf_map_info *info;
+	struct res res = {};
+	__u32 info_len;
+	int fd, err;
+
+	info = map_info_alloc(&info_len);
+	if (!info) {
+		res.nr_errs++;
+		return res;
+	}
+
+	if (wtr)
+		jsonw_start_array(wtr);
+	while ((err = get_next_struct_ops_map(name, &fd, info, info_len)) == 1) {
+		res.nr_maps++;
+		err = func(fd, info, data, wtr);
+		if (err)
+			res.nr_errs++;
+		close(fd);
+	}
+	if (wtr)
+		jsonw_end_array(wtr);
+
+	if (err)
+		res.nr_errs++;
+
+	if (!wtr && name && !res.nr_errs && !res.nr_maps)
+		/* It is not printing empty [].
+		 * Thus, needs to specifically say nothing found
+		 * for "name" here.
+		 */
+		p_err("no struct_ops found for %s", name);
+	else if (!wtr && json_output && !res.nr_errs)
+		/* The "func()" above is not writing any json (i.e. !wtr
+		 * test here).
+		 *
+		 * However, "-j" is enabled and there is no errs here,
+		 * so call json_null() as the current convention of
+		 * other cmds.
+		 */
+		jsonw_null(json_wtr);
+
+	free(info);
+	return res;
+}
+
+static struct res do_one_id(const char *id_str, work_func func, void *data,
+			    struct json_writer *wtr)
+{
+	struct bpf_map_info *info;
+	struct res res = {};
+	unsigned long id;
+	__u32 info_len;
+	char *endptr;
+	int fd;
+
+	id = strtoul(id_str, &endptr, 0);
+	if (*endptr || !id || id > UINT32_MAX) {
+		p_err("invalid id %s", id_str);
+		res.nr_errs++;
+		return res;
+	}
+
+	fd = bpf_map_get_fd_by_id(id);
+	if (fd == -1) {
+		p_err("can't get map by id (%lu): %s", id, strerror(errno));
+		res.nr_errs++;
+		return res;
+	}
+
+	info = map_info_alloc(&info_len);
+	if (!info) {
+		res.nr_errs++;
+		goto done;
+	}
+
+	if (bpf_obj_get_info_by_fd(fd, info, &info_len)) {
+		p_err("can't get map info: %s", strerror(errno));
+		res.nr_errs++;
+		goto done;
+	}
+
+	if (info->type != BPF_MAP_TYPE_STRUCT_OPS) {
+		p_err("%s id %u is not a struct_ops map", info->name, info->id);
+		res.nr_errs++;
+		goto done;
+	}
+
+	res.nr_maps++;
+
+	if (func(fd, info, data, wtr))
+		res.nr_errs++;
+	else if (!wtr && json_output)
+		/* The "func()" above is not writing any json (i.e. !wtr
+		 * test here).
+		 *
+		 * However, "-j" is enabled and there is no errs here,
+		 * so call json_null() as the current convention of
+		 * other cmds.
+		 */
+		jsonw_null(json_wtr);
+
+done:
+	free(info);
+	close(fd);
+
+	return res;
+}
+
+static struct res do_work_on_struct_ops(const char *search_type,
+					const char *search_term,
+					work_func func, void *data,
+					struct json_writer *wtr)
+{
+	if (search_type) {
+		if (is_prefix(search_type, "id"))
+			return do_one_id(search_term, func, data, wtr);
+		else if (!is_prefix(search_type, "name"))
+			usage();
+	}
+
+	return do_search(search_term, func, data, wtr);
+}
+
+static int __do_show(int fd, const struct bpf_map_info *info, void *data,
+		     struct json_writer *wtr)
+{
+	if (wtr) {
+		jsonw_start_object(wtr);
+		jsonw_uint_field(wtr, "id", info->id);
+		jsonw_string_field(wtr, "name", info->name);
+		jsonw_string_field(wtr, "kernel_struct_ops",
+				   get_kern_struct_ops_name(info));
+		jsonw_end_object(wtr);
+	} else {
+		printf("%u: %-15s %-32s\n", info->id, info->name,
+		       get_kern_struct_ops_name(info));
+	}
+
+	return 0;
+}
+
+static int do_show(int argc, char **argv)
+{
+	const char *search_type = NULL, *search_term = NULL;
+	struct res res;
+
+	if (argc && argc != 2)
+		usage();
+
+	if (argc == 2) {
+		search_type = GET_ARG();
+		search_term = GET_ARG();
+	}
+
+	res = do_work_on_struct_ops(search_type, search_term, __do_show,
+				    NULL, json_wtr);
+
+	return cmd_retval(&res, !!search_term);
+}
+
+static int __do_dump(int fd, const struct bpf_map_info *info, void *data,
+		     struct json_writer *wtr)
+{
+	struct btf_dumper *d = (struct btf_dumper *)data;
+	const struct btf_type *struct_ops_type;
+	const struct btf *kern_btf = d->btf;
+	const char *struct_ops_name;
+	int zero = 0;
+	void *value;
+
+	/* note: d->jw == wtr */
+
+	kern_btf = d->btf;
+
+	/* The kernel supporting BPF_MAP_TYPE_STRUCT_OPS must have
+	 * btf_vmlinux_value_type_id.
+	 */
+	struct_ops_type = btf__type_by_id(kern_btf,
+					  info->btf_vmlinux_value_type_id);
+	struct_ops_name = btf__name_by_offset(kern_btf,
+					      struct_ops_type->name_off);
+	value = calloc(1, info->value_size);
+	if (!value) {
+		p_err("mem alloc failed");
+		return -1;
+	}
+
+	if (bpf_map_lookup_elem(fd, &zero, value)) {
+		p_err("can't lookup struct_ops map %s id %u",
+		      info->name, info->id);
+		free(value);
+		return -1;
+	}
+
+	jsonw_start_object(wtr);
+	jsonw_name(wtr, "bpf_map_info");
+	btf_dumper_type(d, map_info_type_id, (void *)info);
+	jsonw_end_object(wtr);
+
+	jsonw_start_object(wtr);
+	jsonw_name(wtr, struct_ops_name);
+	btf_dumper_type(d, info->btf_vmlinux_value_type_id, value);
+	jsonw_end_object(wtr);
+
+	free(value);
+
+	return 0;
+}
+
+static int do_dump(int argc, char **argv)
+{
+	const char *search_type = NULL, *search_term = NULL;
+	json_writer_t *wtr = json_wtr;
+	const struct btf *kern_btf;
+	struct btf_dumper d = {};
+	struct res res;
+
+	if (argc && argc != 2)
+		usage();
+
+	if (argc == 2) {
+		search_type = GET_ARG();
+		search_term = GET_ARG();
+	}
+
+	kern_btf = get_btf_vmlinux();
+	if (IS_ERR(kern_btf))
+		return -1;
+
+	if (!json_output) {
+		wtr = jsonw_new(stdout);
+		if (!wtr) {
+			p_err("can't create json writer");
+			return -1;
+		}
+		jsonw_pretty(wtr, true);
+	}
+
+	d.btf = kern_btf;
+	d.jw = wtr;
+	d.is_plain_text = !json_output;
+	d.prog_id_as_func_ptr = true;
+
+	res = do_work_on_struct_ops(search_type, search_term, __do_dump, &d,
+				    wtr);
+
+	if (!json_output)
+		jsonw_destroy(&wtr);
+
+	return cmd_retval(&res, !!search_term);
+}
+
+static int __do_unregister(int fd, const struct bpf_map_info *info, void *data,
+			   struct json_writer *wtr)
+{
+	int zero = 0;
+
+	if (bpf_map_delete_elem(fd, &zero)) {
+		p_err("can't unload %s %s id %u: %s",
+		      get_kern_struct_ops_name(info), info->name,
+		      info->id, strerror(errno));
+		return -1;
+	}
+
+	p_info("Unregistered %s %s id %u",
+	       get_kern_struct_ops_name(info), info->name,
+	       info->id);
+
+	return 0;
+}
+
+static int do_unregister(int argc, char **argv)
+{
+	const char *search_type, *search_term;
+	struct res res;
+
+	if (argc != 2)
+		usage();
+
+	search_type = GET_ARG();
+	search_term = GET_ARG();
+
+	res = do_work_on_struct_ops(search_type, search_term,
+				    __do_unregister, NULL, NULL);
+
+	return cmd_retval(&res, true);
+}
+
+static int do_register(int argc, char **argv)
+{
+	const struct bpf_map_def *def;
+	struct bpf_map_info info = {};
+	__u32 info_len = sizeof(info);
+	int nr_errs = 0, nr_maps = 0;
+	struct bpf_object *obj;
+	struct bpf_link *link;
+	struct bpf_map *map;
+	const char *file;
+
+	if (argc != 1)
+		usage();
+
+	file = GET_ARG();
+
+	obj = bpf_object__open(file);
+	if (IS_ERR_OR_NULL(obj))
+		return -1;
+
+	set_max_rlimit();
+
+	if (bpf_object__load(obj)) {
+		bpf_object__close(obj);
+		return -1;
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		def = bpf_map__def(map);
+		if (def->type != BPF_MAP_TYPE_STRUCT_OPS)
+			continue;
+
+		link = bpf_map__attach_struct_ops(map);
+		if (IS_ERR(link)) {
+			p_err("can't register struct_ops %s: %s",
+			      bpf_map__name(map),
+			      strerror(-PTR_ERR(link)));
+			nr_errs++;
+			continue;
+		}
+		nr_maps++;
+
+		bpf_link__disconnect(link);
+		bpf_link__destroy(link);
+
+		if (!bpf_obj_get_info_by_fd(bpf_map__fd(map), &info,
+					    &info_len))
+			p_info("Registered %s %s id %u",
+			       get_kern_struct_ops_name(&info),
+			       bpf_map__name(map),
+			       info.id);
+		else
+			/* Not p_err.  The struct_ops was attached
+			 * successfully.
+			 */
+			p_info("Registered %s but can't find id: %s",
+			       bpf_map__name(map), strerror(errno));
+	}
+
+	bpf_object__close(obj);
+
+	if (nr_errs)
+		return -1;
+
+	if (!nr_maps) {
+		p_err("no struct_ops found in %s", file);
+		return -1;
+	}
+
+	if (json_output)
+		jsonw_null(json_wtr);
+
+	return 0;
+}
+
+static int do_help(int argc, char **argv)
+{
+	if (json_output) {
+		jsonw_null(json_wtr);
+		return 0;
+	}
+
+	fprintf(stderr,
+		"Usage: %s %s { show | list } [STRUCT_OPS_MAP]\n"
+		"       %s %s dump [STRUCT_OPS_MAP]\n"
+		"       %s %s register OBJ\n"
+		"       %s %s unregister STRUCT_OPS_MAP\n"
+		"       %s %s help\n"
+		"\n"
+		"       OPTIONS := { {-j|--json} [{-p|--pretty}] }\n"
+		"       STRUCT_OPS_MAP := [ id STRUCT_OPS_MAP_ID | name STRUCT_OPS_MAP_NAME ]\n",
+		bin_name, argv[-2], bin_name, argv[-2],
+		bin_name, argv[-2], bin_name, argv[-2],
+		bin_name, argv[-2]);
+
+	return 0;
+}
+
+static const struct cmd cmds[] = {
+	{ "show",	do_show },
+	{ "list",	do_show },
+	{ "register",	do_register },
+	{ "unregister",	do_unregister },
+	{ "dump",	do_dump },
+	{ "help",	do_help },
+	{ 0 }
+};
+
+int do_struct_ops(int argc, char **argv)
+{
+	int err;
+
+	err = cmd_select(cmds, argc, argv, do_help);
+
+	btf__free(btf_vmlinux);
+	return err;
+}