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![Daniel Xu](/assets/img/avatar_default.png)
This commit marks kfuncs as such inside the .BTF_ids section. The upshot of these annotations is that we'll be able to automatically generate kfunc prototypes for downstream users. The process is as follows: 1. In source, use BTF_KFUNCS_START/END macro pair to mark kfuncs 2. During build, pahole injects into BTF a "bpf_kfunc" BTF_DECL_TAG for each function inside BTF_KFUNCS sets 3. At runtime, vmlinux or module BTF is made available in sysfs 4. At runtime, bpftool (or similar) can look at provided BTF and generate appropriate prototypes for functions with "bpf_kfunc" tag To ensure future kfunc are similarly tagged, we now also return error inside kfunc registration for untagged kfuncs. For vmlinux kfuncs, we also WARN(), as initcall machinery does not handle errors. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Acked-by: Benjamin Tissoires <bentiss@kernel.org> Link: https://lore.kernel.org/r/e55150ceecbf0a5d961e608941165c0bee7bc943.1706491398.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov <ast@kernel.org>
230 lines
5.3 KiB
C
230 lines
5.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2020 Facebook */
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#include <linux/bpf.h>
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#include <linux/fs.h>
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#include <linux/filter.h>
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#include <linux/kernel.h>
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#include <linux/btf_ids.h>
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struct bpf_iter_seq_map_info {
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u32 map_id;
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};
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static void *bpf_map_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct bpf_iter_seq_map_info *info = seq->private;
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struct bpf_map *map;
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map = bpf_map_get_curr_or_next(&info->map_id);
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if (!map)
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return NULL;
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if (*pos == 0)
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++*pos;
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return map;
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}
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static void *bpf_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct bpf_iter_seq_map_info *info = seq->private;
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++*pos;
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++info->map_id;
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bpf_map_put((struct bpf_map *)v);
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return bpf_map_get_curr_or_next(&info->map_id);
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}
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struct bpf_iter__bpf_map {
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__bpf_md_ptr(struct bpf_iter_meta *, meta);
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__bpf_md_ptr(struct bpf_map *, map);
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};
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DEFINE_BPF_ITER_FUNC(bpf_map, struct bpf_iter_meta *meta, struct bpf_map *map)
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static int __bpf_map_seq_show(struct seq_file *seq, void *v, bool in_stop)
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{
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struct bpf_iter__bpf_map ctx;
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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int ret = 0;
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ctx.meta = &meta;
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ctx.map = v;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, in_stop);
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if (prog)
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ret = bpf_iter_run_prog(prog, &ctx);
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return ret;
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}
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static int bpf_map_seq_show(struct seq_file *seq, void *v)
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{
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return __bpf_map_seq_show(seq, v, false);
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}
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static void bpf_map_seq_stop(struct seq_file *seq, void *v)
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{
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if (!v)
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(void)__bpf_map_seq_show(seq, v, true);
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else
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bpf_map_put((struct bpf_map *)v);
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}
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static const struct seq_operations bpf_map_seq_ops = {
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.start = bpf_map_seq_start,
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.next = bpf_map_seq_next,
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.stop = bpf_map_seq_stop,
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.show = bpf_map_seq_show,
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};
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BTF_ID_LIST_GLOBAL_SINGLE(btf_bpf_map_id, struct, bpf_map)
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static const struct bpf_iter_seq_info bpf_map_seq_info = {
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.seq_ops = &bpf_map_seq_ops,
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.init_seq_private = NULL,
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.fini_seq_private = NULL,
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.seq_priv_size = sizeof(struct bpf_iter_seq_map_info),
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};
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static struct bpf_iter_reg bpf_map_reg_info = {
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.target = "bpf_map",
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.ctx_arg_info_size = 1,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__bpf_map, map),
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PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
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},
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.seq_info = &bpf_map_seq_info,
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};
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static int bpf_iter_attach_map(struct bpf_prog *prog,
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union bpf_iter_link_info *linfo,
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struct bpf_iter_aux_info *aux)
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{
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u32 key_acc_size, value_acc_size, key_size, value_size;
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struct bpf_map *map;
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bool is_percpu = false;
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int err = -EINVAL;
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if (!linfo->map.map_fd)
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return -EBADF;
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map = bpf_map_get_with_uref(linfo->map.map_fd);
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if (IS_ERR(map))
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return PTR_ERR(map);
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if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
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map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
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map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
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is_percpu = true;
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else if (map->map_type != BPF_MAP_TYPE_HASH &&
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map->map_type != BPF_MAP_TYPE_LRU_HASH &&
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map->map_type != BPF_MAP_TYPE_ARRAY)
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goto put_map;
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key_acc_size = prog->aux->max_rdonly_access;
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value_acc_size = prog->aux->max_rdwr_access;
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key_size = map->key_size;
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if (!is_percpu)
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value_size = map->value_size;
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else
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value_size = round_up(map->value_size, 8) * num_possible_cpus();
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if (key_acc_size > key_size || value_acc_size > value_size) {
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err = -EACCES;
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goto put_map;
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}
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aux->map = map;
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return 0;
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put_map:
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bpf_map_put_with_uref(map);
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return err;
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}
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static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
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{
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bpf_map_put_with_uref(aux->map);
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}
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void bpf_iter_map_show_fdinfo(const struct bpf_iter_aux_info *aux,
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struct seq_file *seq)
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{
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seq_printf(seq, "map_id:\t%u\n", aux->map->id);
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}
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int bpf_iter_map_fill_link_info(const struct bpf_iter_aux_info *aux,
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struct bpf_link_info *info)
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{
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info->iter.map.map_id = aux->map->id;
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return 0;
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}
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DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta,
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struct bpf_map *map, void *key, void *value)
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static const struct bpf_iter_reg bpf_map_elem_reg_info = {
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.target = "bpf_map_elem",
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.attach_target = bpf_iter_attach_map,
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.detach_target = bpf_iter_detach_map,
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.show_fdinfo = bpf_iter_map_show_fdinfo,
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.fill_link_info = bpf_iter_map_fill_link_info,
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.ctx_arg_info_size = 2,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__bpf_map_elem, key),
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PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
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{ offsetof(struct bpf_iter__bpf_map_elem, value),
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PTR_TO_BUF | PTR_MAYBE_NULL },
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},
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};
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static int __init bpf_map_iter_init(void)
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{
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int ret;
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bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;
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ret = bpf_iter_reg_target(&bpf_map_reg_info);
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if (ret)
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return ret;
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return bpf_iter_reg_target(&bpf_map_elem_reg_info);
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}
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late_initcall(bpf_map_iter_init);
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__bpf_kfunc_start_defs();
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__bpf_kfunc s64 bpf_map_sum_elem_count(const struct bpf_map *map)
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{
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s64 *pcount;
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s64 ret = 0;
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int cpu;
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if (!map || !map->elem_count)
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return 0;
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for_each_possible_cpu(cpu) {
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pcount = per_cpu_ptr(map->elem_count, cpu);
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ret += READ_ONCE(*pcount);
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}
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return ret;
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}
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__bpf_kfunc_end_defs();
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BTF_KFUNCS_START(bpf_map_iter_kfunc_ids)
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BTF_ID_FLAGS(func, bpf_map_sum_elem_count, KF_TRUSTED_ARGS)
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BTF_KFUNCS_END(bpf_map_iter_kfunc_ids)
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static const struct btf_kfunc_id_set bpf_map_iter_kfunc_set = {
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.owner = THIS_MODULE,
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.set = &bpf_map_iter_kfunc_ids,
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};
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static int init_subsystem(void)
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{
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return register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC, &bpf_map_iter_kfunc_set);
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}
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late_initcall(init_subsystem);
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