netdev - [PATCHv4 bpf-next 4/8] bpf: Add bpf_get_func

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Message-Id: <20210714094400.396467-5-jolsa@kernel.org>
Date:   Wed, 14 Jul 2021 11:43:56 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     kernel test robot <lkp@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCHv4 bpf-next 4/8] 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.

[removed duplicate include]
Reported-by: kernel test robot <lkp@...el.com>
Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 include/uapi/linux/bpf.h       |  2 +-
 kernel/bpf/verifier.c          |  2 ++
 kernel/trace/bpf_trace.c       | 16 ++++++++++++++++
 tools/include/uapi/linux/bpf.h |  2 +-
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 31dd386b64ec..3ea5874f603b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4780,7 +4780,7 @@ 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 d27aa23fb572..9998ffc00bbd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5969,6 +5969,8 @@ 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 022cbe42ac57..8af385fd5419 100644
--- 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 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