linux-kernel - [PATCHv3 bpf-next 04/13] bpf: Add bpf_get_func

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Message-Id: <20220316122419.933957-5-jolsa@kernel.org>
Date:   Wed, 16 Mar 2022 13:24:10 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        lkml <linux-kernel@...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>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCHv3 bpf-next 04/13] bpf: Add bpf_get_func_ip kprobe helper for multi kprobe link

Adding support to call bpf_get_func_ip helper from kprobe
programs attached by multi kprobe link.

Acked-by: Andrii Nakryiko <andrii@...nel.org>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/trace/bpf_trace.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index fffa2171fae4..250750932228 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1037,6 +1037,18 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 };
 
+BPF_CALL_1(bpf_get_func_ip_kprobe_multi, struct pt_regs *, regs)
+{
+	return instruction_pointer(regs);
+}
+
+static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe_multi = {
+	.func		= bpf_get_func_ip_kprobe_multi,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
 BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
 {
 	struct bpf_trace_run_ctx *run_ctx;
@@ -1280,7 +1292,9 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_override_return_proto;
 #endif
 	case BPF_FUNC_get_func_ip:
-		return &bpf_get_func_ip_proto_kprobe;
+		return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ?
+			&bpf_get_func_ip_proto_kprobe_multi :
+			&bpf_get_func_ip_proto_kprobe;
 	case BPF_FUNC_get_attach_cookie:
 		return &bpf_get_attach_cookie_proto_trace;
 	default:
-- 
2.35.1