[PATCH bpf-next v11 05/13] bpf: make struct_ops_map support btfs other than btf_vmlinux.

thinker.li
2023-11-06T20:13:09Z

From: Kui-Feng Lee <thinker.li@gmail.com>

Once new struct_ops can be registered from modules, btf_vmlinux is not
longer the only btf tht 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>
---
kernel/bpf/bpf_struct_ops.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index d804801c7864..a0291877a792 100644
--- 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;
@@ -395,12 +397,12 @@ 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;

@@ -436,7 +438,7 @@ 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;
@@ -461,8 +463,8 @@ 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;
@@ -601,6 +603,7 @@ 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;

@@ -610,7 +613,8 @@ 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");
}
@@ -720,6 +724,8 @@ 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);
set_vm_flush_reset_perms(st_map->image);
bpf_map_init_from_attr(map, attr);
--
2.34.1