bpf: Add bpf_get_func_ip helper for kprobe programs

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.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-5-jolsa@kernel.org

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 89688f1..2db6925 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4844,7 +4844,7 @@ 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 ceef190..97216f7 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6175,6 +6175,8 @@ static int check_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 3e71503..0b11371 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -961,6 +961,20 @@ 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 +1106,8 @@ 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 89688f1..2db6925 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4844,7 +4844,7 @@ 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.
  */