On Thu, Nov 3, 2022 at 8:21 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Add bpf_rcu_read_lock() and bpf_rcu_read_unlock() helpers.
> Both helpers are available to all program types with
> CAP_BPF capability.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
> include/linux/bpf.h | 2 ++
> include/uapi/linux/bpf.h | 14 ++++++++++++++
> kernel/bpf/core.c | 2 ++
> kernel/bpf/helpers.c | 26 ++++++++++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 14 ++++++++++++++
> 5 files changed, 58 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 8d948bfcb984..a9bda4c91fc7 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -2554,6 +2554,8 @@ 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_rcu_read_lock_proto;
> +extern const struct bpf_func_proto bpf_rcu_read_unlock_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 94659f6b3395..e86389cd6133 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -5481,6 +5481,18 @@ union bpf_attr {
> * 0 on success.
> *
> * **-ENOENT** if the bpf_local_storage cannot be found.
> + *
> + * void bpf_rcu_read_lock(void)
> + * Description
> + * Call kernel rcu_read_lock().
Simple wrapper around rcu_read_lock() and maybe explain where and how
it is supposed to
be used.
e.g. the verifier will check if __rcu pointers are being accessed with
bpf_rcu_read_lock in
sleepable programs.
Calling the helper from a non-sleepable program is inconsequential,
but maybe we can even
avoid exposing it to non-sleepable programs?
> + * Return
> + * None.
> + *
> + * void bpf_rcu_read_unlock(void)
> + * Description
> + * Call kernel rcu_read_unlock().
> + * Return
> + * None.
> */
> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
> FN(unspec, 0, ##ctx) \
> @@ -5695,6 +5707,8 @@ union bpf_attr {
> FN(user_ringbuf_drain, 209, ##ctx) \
> FN(cgrp_storage_get, 210, ##ctx) \
> FN(cgrp_storage_delete, 211, ##ctx) \
> + FN(rcu_read_lock, 212, ##ctx) \
> + FN(rcu_read_unlock, 213, ##ctx) \
> /* */
>
> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 9c16338bcbe8..26858b579dfc 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2627,6 +2627,8 @@ const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto __weak;
> const struct bpf_func_proto bpf_spin_lock_proto __weak;
> const struct bpf_func_proto bpf_spin_unlock_proto __weak;
> const struct bpf_func_proto bpf_jiffies64_proto __weak;
> +const struct bpf_func_proto bpf_rcu_read_lock_proto __weak;
> +const struct bpf_func_proto bpf_rcu_read_unlock_proto __weak;
>
> const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
> const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 124fd199ce5c..f19416dc8ad1 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -1273,6 +1273,28 @@ static const struct bpf_func_proto bpf_timer_start_proto = {
> .arg3_type = ARG_ANYTHING,
> };
>
> +BPF_CALL_0(bpf_rcu_read_lock) {
> + rcu_read_lock();
> + return 0;
> +}
> +
> +const struct bpf_func_proto bpf_rcu_read_lock_proto = {
> + .func = bpf_rcu_read_lock,
> + .gpl_only = false,
> + .ret_type = RET_VOID,
> +};
> +
> +BPF_CALL_0(bpf_rcu_read_unlock) {
> + rcu_read_unlock();
> + return 0;
> +}
> +
> +const struct bpf_func_proto bpf_rcu_read_unlock_proto = {
> + .func = bpf_rcu_read_unlock,
> + .gpl_only = false,
> + .ret_type = RET_VOID,
> +};
> +
> static void drop_prog_refcnt(struct bpf_hrtimer *t)
> {
> struct bpf_prog *prog = t->prog;
> @@ -1627,6 +1649,10 @@ bpf_base_func_proto(enum bpf_func_id func_id)
> return &bpf_spin_lock_proto;
> case BPF_FUNC_spin_unlock:
> return &bpf_spin_unlock_proto;
> + case BPF_FUNC_rcu_read_lock:
> + return &bpf_rcu_read_lock_proto;
> + case BPF_FUNC_rcu_read_unlock:
> + return &bpf_rcu_read_unlock_proto;
> case BPF_FUNC_jiffies64:
> return &bpf_jiffies64_proto;
> case BPF_FUNC_per_cpu_ptr:
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 94659f6b3395..e86389cd6133 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -5481,6 +5481,18 @@ union bpf_attr {
> * 0 on success.
> *
> * **-ENOENT** if the bpf_local_storage cannot be found.
> + *
> + * void bpf_rcu_read_lock(void)
> + * Description
> + * Call kernel rcu_read_lock().
> + * Return
> + * None.
> + *
> + * void bpf_rcu_read_unlock(void)
> + * Description
> + * Call kernel rcu_read_unlock().
> + * Return
> + * None.
> */
> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
> FN(unspec, 0, ##ctx) \
> @@ -5695,6 +5707,8 @@ union bpf_attr {
> FN(user_ringbuf_drain, 209, ##ctx) \
> FN(cgrp_storage_get, 210, ##ctx) \
> FN(cgrp_storage_delete, 211, ##ctx) \
> + FN(rcu_read_lock, 212, ##ctx) \
> + FN(rcu_read_unlock, 213, ##ctx) \
> /* */
>
> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> --
> 2.30.2
>
On Thu, Nov 3, 2022 at 8:21 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Add bpf_rcu_read_lock() and bpf_rcu_read_unlock() helpers.
> Both helpers are available to all program types with
> CAP_BPF capability.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
> include/linux/bpf.h | 2 ++
> include/uapi/linux/bpf.h | 14 ++++++++++++++
> kernel/bpf/core.c | 2 ++
> kernel/bpf/helpers.c | 26 ++++++++++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 14 ++++++++++++++
> 5 files changed, 58 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 8d948bfcb984..a9bda4c91fc7 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -2554,6 +2554,8 @@ 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_rcu_read_lock_proto;
> +extern const struct bpf_func_proto bpf_rcu_read_unlock_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 94659f6b3395..e86389cd6133 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -5481,6 +5481,18 @@ union bpf_attr {
> * 0 on success.
> *
> * **-ENOENT** if the bpf_local_storage cannot be found.
> + *
> + * void bpf_rcu_read_lock(void)
> + * Description
> + * Call kernel rcu_read_lock().
> + * Return
> + * None.
> + *
> + * void bpf_rcu_read_unlock(void)
> + * Description
> + * Call kernel rcu_read_unlock().
> + * Return
> + * None.
> */
> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
> FN(unspec, 0, ##ctx) \
> @@ -5695,6 +5707,8 @@ union bpf_attr {
> FN(user_ringbuf_drain, 209, ##ctx) \
> FN(cgrp_storage_get, 210, ##ctx) \
> FN(cgrp_storage_delete, 211, ##ctx) \
> + FN(rcu_read_lock, 212, ##ctx) \
> + FN(rcu_read_unlock, 213, ##ctx) \
> /* */
>
> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 9c16338bcbe8..26858b579dfc 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2627,6 +2627,8 @@ const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto __weak;
> const struct bpf_func_proto bpf_spin_lock_proto __weak;
> const struct bpf_func_proto bpf_spin_unlock_proto __weak;
> const struct bpf_func_proto bpf_jiffies64_proto __weak;
> +const struct bpf_func_proto bpf_rcu_read_lock_proto __weak;
> +const struct bpf_func_proto bpf_rcu_read_unlock_proto __weak;
>
> const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
> const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 124fd199ce5c..f19416dc8ad1 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -1273,6 +1273,28 @@ static const struct bpf_func_proto bpf_timer_start_proto = {
> .arg3_type = ARG_ANYTHING,
> };
>
> +BPF_CALL_0(bpf_rcu_read_lock) {
> + rcu_read_lock();
> + return 0;
> +}
> +
> +const struct bpf_func_proto bpf_rcu_read_lock_proto = {
> + .func = bpf_rcu_read_lock,
> + .gpl_only = false,
> + .ret_type = RET_VOID,
> +};
> +
> +BPF_CALL_0(bpf_rcu_read_unlock) {
> + rcu_read_unlock();
> + return 0;
> +}
> +
> +const struct bpf_func_proto bpf_rcu_read_unlock_proto = {
> + .func = bpf_rcu_read_unlock,
> + .gpl_only = false,
> + .ret_type = RET_VOID,
> +};
> +
> static void drop_prog_refcnt(struct bpf_hrtimer *t)
> {
> struct bpf_prog *prog = t->prog;
> @@ -1627,6 +1649,10 @@ bpf_base_func_proto(enum bpf_func_id func_id)
> return &bpf_spin_lock_proto;
> case BPF_FUNC_spin_unlock:
> return &bpf_spin_unlock_proto;
> + case BPF_FUNC_rcu_read_lock:
> + return &bpf_rcu_read_lock_proto;
> + case BPF_FUNC_rcu_read_unlock:
> + return &bpf_rcu_read_unlock_proto;
> case BPF_FUNC_jiffies64:
> return &bpf_jiffies64_proto;
> case BPF_FUNC_per_cpu_ptr:
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 94659f6b3395..e86389cd6133 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -5481,6 +5481,18 @@ union bpf_attr {
> * 0 on success.
> *
> * **-ENOENT** if the bpf_local_storage cannot be found.
> + *
> + * void bpf_rcu_read_lock(void)
> + * Description
> + * Call kernel rcu_read_lock().
> + * Return
> + * None.
> + *
> + * void bpf_rcu_read_unlock(void)
> + * Description
> + * Call kernel rcu_read_unlock().
> + * Return
> + * None.
> */
> #define ___BPF_FUNC_MAPPER(FN, ctx...) \
> FN(unspec, 0, ##ctx) \
> @@ -5695,6 +5707,8 @@ union bpf_attr {
> FN(user_ringbuf_drain, 209, ##ctx) \
> FN(cgrp_storage_get, 210, ##ctx) \
> FN(cgrp_storage_delete, 211, ##ctx) \
> + FN(rcu_read_lock, 212, ##ctx) \
> + FN(rcu_read_unlock, 213, ##ctx) \
> /* */
>
> /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> --
> 2.30.2
>
