bpf: make struct_ops_map support btfs other than btf_vmlinux.

Once new struct_ops can be registered from modules, btf_vmlinux is no
longer the only btf that struct_ops_map would face.  st_map should remember
what btf it should use to get type information.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-6-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 9774f78..5ddcca4 100644 (file)
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -46,6 +46,8 @@ struct bpf_struct_ops_map {
         * "links[]".
         */
        void *image;
+       /* The owner moduler's btf. */
+       struct btf *btf;
        /* uvalue->data stores the kernel struct
         * (e.g. tcp_congestion_ops) that is more useful
         * to userspace than the kvalue.  For example,
@@ -314,7 +316,7 @@ static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map)
        }
 }
 
-static int check_zero_holes(const struct btf_type *t, void *data)
+static int check_zero_holes(const struct btf *btf, const struct btf_type *t, void *data)
 {
        const struct btf_member *member;
        u32 i, moff, msize, prev_mend = 0;
@@ -326,8 +328,8 @@ static int check_zero_holes(const struct btf_type *t, void *data)
                    memchr_inv(data + prev_mend, 0, moff - prev_mend))
                        return -EINVAL;
 
-               mtype = btf_type_by_id(btf_vmlinux, member->type);
-               mtype = btf_resolve_size(btf_vmlinux, mtype, &msize);
+               mtype = btf_type_by_id(btf, member->type);
+               mtype = btf_resolve_size(btf, mtype, &msize);
                if (IS_ERR(mtype))
                        return PTR_ERR(mtype);
                prev_mend = moff + msize;
@@ -401,12 +403,12 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
        if (*(u32 *)key != 0)
                return -E2BIG;
 
-       err = check_zero_holes(st_ops_desc->value_type, value);
+       err = check_zero_holes(st_map->btf, st_ops_desc->value_type, value);
        if (err)
                return err;
 
        uvalue = value;
-       err = check_zero_holes(t, uvalue->data);
+       err = check_zero_holes(st_map->btf, t, uvalue->data);
        if (err)
                return err;
 
@@ -442,7 +444,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
                u32 moff;
 
                moff = __btf_member_bit_offset(t, member) / 8;
-               ptype = btf_type_resolve_ptr(btf_vmlinux, member->type, NULL);
+               ptype = btf_type_resolve_ptr(st_map->btf, member->type, NULL);
                if (ptype == module_type) {
                        if (*(void **)(udata + moff))
                                goto reset_unlock;
@@ -467,8 +469,8 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
                if (!ptype || !btf_type_is_func_proto(ptype)) {
                        u32 msize;
 
-                       mtype = btf_type_by_id(btf_vmlinux, member->type);
-                       mtype = btf_resolve_size(btf_vmlinux, mtype, &msize);
+                       mtype = btf_type_by_id(st_map->btf, member->type);
+                       mtype = btf_resolve_size(st_map->btf, mtype, &msize);
                        if (IS_ERR(mtype)) {
                                err = PTR_ERR(mtype);
                                goto reset_unlock;
@@ -607,6 +609,7 @@ static long bpf_struct_ops_map_delete_elem(struct bpf_map *map, void *key)
 static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key,
                                             struct seq_file *m)
 {
+       struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;
        void *value;
        int err;
 
@@ -616,7 +619,8 @@ static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key,
 
        err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
        if (!err) {
-               btf_type_seq_show(btf_vmlinux, map->btf_vmlinux_value_type_id,
+               btf_type_seq_show(st_map->btf,
+                                 map->btf_vmlinux_value_type_id,
                                  value, m);
                seq_puts(m, "\n");
        }
@@ -726,6 +730,8 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
                return ERR_PTR(-ENOMEM);
        }
 
+       st_map->btf = btf_vmlinux;
+
        mutex_init(&st_map->lock);
        bpf_map_init_from_attr(map, attr);