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 /include/linux | |
| parent | d198b27762644c71362e43a7533f89c92b115bcf (diff) | |
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 'include/linux')
| -rw-r--r-- | include/linux/bpf.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f4c16f19f83e..020a7d5bf470 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -578,11 +578,12 @@ struct btf_func_model { * programs only. Should not be used with normal calls and indirect calls. */ #define BPF_TRAMP_F_SKIP_FRAME BIT(2) - /* Store IP address of the caller on the trampoline stack, * so it's available for trampoline's programs. */ #define BPF_TRAMP_F_IP_ARG BIT(3) +/* Return the return value of fentry prog. Only used by bpf_struct_ops. */ +#define BPF_TRAMP_F_RET_FENTRY_RET BIT(4) /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 * bytes on x86. Pick a number to fit into BPF_IMAGE_SIZE / 2 |