github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-25 23:52:08 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

bpf: allow using bpf_kptr_xchg even if the MEM_RCU flag is set

Browse Source 
For the following scenario:
    struct tree_node {
	struct bpf_refcount ref;
	struct bpf_rb_node node;
	struct node_data __kptr * node_data;
	u64 key;
    };
This means node_data would have the type PTR_TO_BTF_ID | MEM_ALLOC |
NON_OWN_REF | MEM_RCU.

When traversing an rbtree using bpf_rbtree_left/right, if we need to
use bpf_kptr_xchg to read the __kptr pointer, we still need to follow
the remove-read-add sequence.

This patch allows us to use bpf_kptr_xchg to directly read the __kptr
pointer without any prior operations.

Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Link: https://lore.kernel.org/r/20260214124042.62229-5-pilgrimtao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kaitao Cheng 2026-02-14 20:40:41 +08:00 committed by Alexei Starovoitov
parent 580fa3430b
commit fb1590448f
1 changed files with 2 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/bpf/verifier.c
View File

@ -9311,6 +9311,7 @@ static const struct bpf_reg_types kptr_xchg_dest_types = {
PTR_TO_MAP_VALUE,
PTR_TO_BTF_ID | MEM_ALLOC,
PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF,
PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU,
}
};
static const struct bpf_reg_types dynptr_types = {
@ -9475,6 +9476,7 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
case PTR_TO_BTF_ID | MEM_ALLOC:
case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC:
case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU:
if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock &&
meta->func_id != BPF_FUNC_kptr_xchg) {
verifier_bug(env, "unimplemented handling of MEM_ALLOC");