On Wed, 7 Jul 2021 23:47:48 +0200
Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs,
> so it's now possible to call bpf_get_func_ip from both kprobe and
> kretprobe programs.
>
> Taking the caller's address from 'struct kprobe::addr', which is
> defined for both kprobe and kretprobe.
>
Note that the kp->addr of kretprobe will be the callee function
address, even if the handler is called when the end of the callee.
Anyway, this looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Thank you,
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 2 +-
> kernel/bpf/verifier.c | 2 ++
> kernel/trace/bpf_trace.c | 17 +++++++++++++++++
> tools/include/uapi/linux/bpf.h | 2 +-
> 4 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 83e87ffdbb6e..4894f99a1993 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -4783,7 +4783,7 @@ union bpf_attr {
> *
> * u64 bpf_get_func_ip(void *ctx)
> * Description
> - * Get address of the traced function (for tracing programs).
> + * Get address of the traced function (for tracing and kprobe programs).
> * Return
> * Address of the traced function.
> */
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index f975a3aa9368..79eb9d81a198 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -5979,6 +5979,8 @@ static int has_get_func_ip(struct bpf_verifier_env *env)
> return -ENOTSUPP;
> }
> return 0;
> + } else if (type == BPF_PROG_TYPE_KPROBE) {
> + return 0;
> }
>
> verbose(env, "func %s#%d not supported for program type %d\n",
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 9edd3b1a00ad..55acf56b0c3a 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -17,6 +17,7 @@
> #include <linux/error-injection.h>
> #include <linux/btf_ids.h>
> #include <linux/bpf_lsm.h>
> +#include <linux/kprobes.h>
>
> #include <net/bpf_sk_storage.h>
>
> @@ -961,6 +962,20 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = {
> .arg1_type = ARG_PTR_TO_CTX,
> };
>
> +BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
> +{
> + struct kprobe *kp = kprobe_running();
> +
> + return kp ? (u64) kp->addr : 0;
> +}
> +
> +static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
> + .func = bpf_get_func_ip_kprobe,
> + .gpl_only = true,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> +};
> +
> const struct bpf_func_proto *
> bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> {
> @@ -1092,6 +1107,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> case BPF_FUNC_override_return:
> return &bpf_override_return_proto;
> #endif
> + case BPF_FUNC_get_func_ip:
> + return &bpf_get_func_ip_proto_kprobe;
> default:
> return bpf_tracing_func_proto(func_id, prog);
> }
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 83e87ffdbb6e..4894f99a1993 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -4783,7 +4783,7 @@ union bpf_attr {
> *
> * u64 bpf_get_func_ip(void *ctx)
> * Description
> - * Get address of the traced function (for tracing programs).
> + * Get address of the traced function (for tracing and kprobe programs).
> * Return
> * Address of the traced function.
> */
> --
> 2.31.1
>
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
