On Fri, Dec 22, 2023 at 08:21:46PM +0800, Philo Lu wrote:
> Like perfbuf/ringbuf, a helper is needed to write into the buffer, named
> bpf_relay_output, whose usage is same as ringbuf. Note that it works only
> after relay files are set, i.e., after calling map_update_elem for the
> created relay map.
we can't add helpers anymore, this will need to be kfunc
check functions marked with __bpf_kfunc as examples
jirka
>
> Signed-off-by: Philo Lu <lulie@xxxxxxxxxxxxxxxxx>
> ---
> include/linux/bpf.h | 1 +
> include/uapi/linux/bpf.h | 10 ++++++++++
> kernel/bpf/helpers.c | 4 ++++
> kernel/bpf/relaymap.c | 26 ++++++++++++++++++++++++++
> kernel/bpf/verifier.c | 8 ++++++++
> kernel/trace/bpf_trace.c | 4 ++++
> 6 files changed, 53 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 7671530d6e4e..b177122369e6 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -3095,6 +3095,7 @@ extern const struct bpf_func_proto bpf_get_retval_proto;
> extern const struct bpf_func_proto bpf_user_ringbuf_drain_proto;
> extern const struct bpf_func_proto bpf_cgrp_storage_get_proto;
> extern const struct bpf_func_proto bpf_cgrp_storage_delete_proto;
> +extern const struct bpf_func_proto bpf_relay_output_proto;
>
> const struct bpf_func_proto *tracing_prog_func_proto(
> enum bpf_func_id func_id, const struct bpf_prog *prog);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 143b75676bd3..03c0c1953ba1 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -5686,6 +5686,15 @@ union bpf_attr {
> * 0 on success.
> *
> * **-ENOENT** if the bpf_local_storage cannot be found.
> + *
> + * long bpf_relay_output(void *map, void *data, u64 size, u64 flags)
> + * Description
> + * Copy *size* bytes from *data* into *map* of type BPF_MAP_TYPE_RELAY.
> + * Currently, the *flags* must be 0.
> + * Return
> + * 0 on success.
> + *
> + * **-ENOENT** if the relay base_file in debugfs cannot be found.
> */
> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
> FN(unspec, 0, ##ctx) \
> @@ -5900,6 +5909,7 @@ union bpf_attr {
> FN(user_ringbuf_drain, 209, ##ctx) \
> FN(cgrp_storage_get, 210, ##ctx) \
> FN(cgrp_storage_delete, 211, ##ctx) \
> + FN(relay_output, 212, ##ctx) \
> /* */
>
> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index be72824f32b2..0c26e87ce729 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -1720,6 +1720,10 @@ bpf_base_func_proto(enum bpf_func_id func_id)
> return &bpf_ringbuf_discard_proto;
> case BPF_FUNC_ringbuf_query:
> return &bpf_ringbuf_query_proto;
> +#ifdef CONFIG_RELAY
> + case BPF_FUNC_relay_output:
> + return &bpf_relay_output_proto;
> +#endif
> case BPF_FUNC_strncmp:
> return &bpf_strncmp_proto;
> case BPF_FUNC_strtol:
> diff --git a/kernel/bpf/relaymap.c b/kernel/bpf/relaymap.c
> index 588c8de0a4bd..f9e2e4a780df 100644
> --- a/kernel/bpf/relaymap.c
> +++ b/kernel/bpf/relaymap.c
> @@ -173,6 +173,32 @@ static u64 relay_map_mem_usage(const struct bpf_map *map)
> return usage;
> }
>
> +BPF_CALL_4(bpf_relay_output, struct bpf_map *, map, void *, data, u64, size,
> + u64, flags)
> +{
> + struct bpf_relay_map *rmap;
> +
> + /* not support any flag now */
> + if (unlikely(flags))
> + return -EINVAL;
> +
> + rmap = container_of(map, struct bpf_relay_map, map);
> + if (!rmap->relay_chan->has_base_filename)
> + return -ENOENT;
> +
> + relay_write(rmap->relay_chan, data, size);
> + return 0;
> +}
> +
> +const struct bpf_func_proto bpf_relay_output_proto = {
> + .func = bpf_relay_output,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_CONST_MAP_PTR,
> + .arg2_type = ARG_PTR_TO_MEM | MEM_RDONLY,
> + .arg3_type = ARG_CONST_SIZE_OR_ZERO,
> + .arg4_type = ARG_ANYTHING,
> +};
> +
> BTF_ID_LIST_SINGLE(relay_map_btf_ids, struct, bpf_relay_map)
> const struct bpf_map_ops relay_map_ops = {
> .map_meta_equal = bpf_map_meta_equal,
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index f13008d27f35..8c8287d6ae18 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -8800,6 +8800,10 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> if (func_id != BPF_FUNC_user_ringbuf_drain)
> goto error;
> break;
> + case BPF_MAP_TYPE_RELAY:
> + if (func_id != BPF_FUNC_relay_output)
> + goto error;
> + break;
> case BPF_MAP_TYPE_STACK_TRACE:
> if (func_id != BPF_FUNC_get_stackid)
> goto error;
> @@ -8932,6 +8936,10 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
> if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF)
> goto error;
> break;
> + case BPF_FUNC_relay_output:
> + if (map->map_type != BPF_MAP_TYPE_RELAY)
> + goto error;
> + break;
> case BPF_FUNC_get_stackid:
> if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
> goto error;
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 7ac6c52b25eb..5b13553c6232 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1594,6 +1594,10 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> return &bpf_ringbuf_discard_proto;
> case BPF_FUNC_ringbuf_query:
> return &bpf_ringbuf_query_proto;
> +#ifdef CONFIG_RELAY
> + case BPF_FUNC_relay_output:
> + return &bpf_relay_output_proto;
> +#endif
> case BPF_FUNC_jiffies64:
> return &bpf_jiffies64_proto;
> case BPF_FUNC_get_task_stack:
> --
> 2.32.0.3.g01195cf9f
>
