diff options
| author | Hou Tao <houtao1@huawei.com> | 2021-09-14 10:33:51 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-09-14 11:09:50 -0700 |
| commit | 356ed64991c6847a0c4f2e8fa3b1133f7a14f1fc (patch) | |
| tree | 770425a34bcd9a948033c5164e64a127e1b4a94c /kernel | |
| parent | d198b27762644c71362e43a7533f89c92b115bcf (diff) | |
| download | lwn-356ed64991c6847a0c4f2e8fa3b1133f7a14f1fc.tar.gz lwn-356ed64991c6847a0c4f2e8fa3b1133f7a14f1fc.zip | |
bpf: Handle return value of BPF_PROG_TYPE_STRUCT_OPS prog
Currently if a function ptr in struct_ops has a return value, its
caller will get a random return value from it, because the return
value of related BPF_PROG_TYPE_STRUCT_OPS prog is just dropped.
So adding a new flag BPF_TRAMP_F_RET_FENTRY_RET to tell bpf trampoline
to save and return the return value of struct_ops prog if ret_size of
the function ptr is greater than 0. Also restricting the flag to be
used alone.
Fixes: 85d33df357b6 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914023351.3664499-1-houtao1@huawei.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/bpf_struct_ops.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index d6731c32864e..9abcc33f02cf 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -368,6 +368,7 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, const struct btf_type *mtype, *ptype; struct bpf_prog *prog; u32 moff; + u32 flags; moff = btf_member_bit_offset(t, member) / 8; ptype = btf_type_resolve_ptr(btf_vmlinux, member->type, NULL); @@ -431,10 +432,12 @@ static int bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key, tprogs[BPF_TRAMP_FENTRY].progs[0] = prog; tprogs[BPF_TRAMP_FENTRY].nr_progs = 1; + flags = st_ops->func_models[i].ret_size > 0 ? + BPF_TRAMP_F_RET_FENTRY_RET : 0; err = arch_prepare_bpf_trampoline(NULL, image, st_map->image + PAGE_SIZE, - &st_ops->func_models[i], 0, - tprogs, NULL); + &st_ops->func_models[i], + flags, tprogs, NULL); if (err < 0) goto reset_unlock; |