[RFC PATCH bpf-next 07/16] bpf: add bpf_map target

Yonghong Song
2020-04-08T23:25:48Z

This patch added bpf_map target. Traversing all bpf_maps
through map_idr. A reference is held for the map during
the show() to ensure safety and correctness for field accesses.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/syscall.c | 104 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 104 insertions(+)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b5e4f18cc633..62a872a406ca 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3797,3 +3797,107 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz

return err;
}
+
+struct bpfdump_seq_map_info {
+ struct bpf_map *map;
+ u32 id;
+};
+
+static struct bpf_map *bpf_map_seq_get_next(u32 *id)
+{
+ struct bpf_map *map;
+
+ spin_lock_bh(&map_idr_lock);
+ map = idr_get_next(&map_idr, id);
+ if (map)
+ map = __bpf_map_inc_not_zero(map, false);
+ spin_unlock_bh(&map_idr_lock);
+
+ return map;
+}
+
+static void *bpf_map_seq_start(struct seq_file *seq, loff_t *pos)
+{
+ struct bpfdump_seq_map_info *info = seq->private;
+ struct bpf_map *map;
+ u32 id = info->id + 1;
+
+ map = bpf_map_seq_get_next(&id);
+ if (!map)
+ return NULL;
+
+ ++*pos;
+ info->map = map;
+ info->id = id;
+ return map;
+}
+
+static void *bpf_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+ struct bpfdump_seq_map_info *info = seq->private;
+ struct bpf_map *map;
+ u32 id = info->id + 1;
+
+ ++*pos;
+ map = bpf_map_seq_get_next(&id);
+ if (!map)
+ return NULL;
+
+ __bpf_map_put(info->map, true);
+ info->map = map;
+ info->id = id;
+ return map;
+}
+
+static void bpf_map_seq_stop(struct seq_file *seq, void *v)
+{
+ struct bpfdump_seq_map_info *info = seq->private;
+
+ if (info->map) {
+ __bpf_map_put(info->map, true);
+ info->map = NULL;
+ }
+}
+
+static int bpf_map_seq_show(struct seq_file *seq, void *v)
+{
+ struct {
+ struct bpf_map *map;
+ struct seq_file *seq;
+ u64 seq_num;
+ } ctx = {
+ .map = v,
+ .seq = seq,
+ };
+ struct bpf_prog *prog;
+ int ret;
+
+ prog = bpf_dump_get_prog(seq, sizeof(struct bpfdump_seq_map_info),
+ &ctx.seq_num);
+ ret = bpf_dump_run_prog(prog, &ctx);
+
+ return ret == 0 ? 0 : -EINVAL;
+}
+
+static const struct seq_operations bpf_map_seq_ops = {
+ .start = bpf_map_seq_start,
+ .next = bpf_map_seq_next,
+ .stop = bpf_map_seq_stop,
+ .show = bpf_map_seq_show,
+};
+
+int __init bpfdump__bpf_map(struct bpf_map *map, struct seq_file *seq,
+ u64 seq_num)
+{
+ return 0;
+}
+
+static int __init bpf_map_dump_init(void)
+{
+ return bpf_dump_reg_target("bpf_map",
+ "bpfdump__bpf_map",
+ &bpf_map_seq_ops,
+ sizeof(struct bpfdump_seq_map_info), 0);
+}
+
+late_initcall(bpf_map_dump_init);
--
2.24.1