netdev - [PATCH RFC bpf-next 4/4] selftests/bpf: Fix kprobe get_func_ip tests for CONFIG_X86_KERNEL

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Date:   Tue,  5 Jul 2022 21:03:08 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     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>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Martynas Pumputis <m@...bda.lt>,
        Yutaro Hayakawa <yutaro.hayakawa@...valent.com>
Subject: [PATCH RFC bpf-next 4/4] selftests/bpf: Fix kprobe get_func_ip tests for CONFIG_X86_KERNEL_IBT

The kprobe can be placed anywhere and user must be aware
of the underlying instructions. Therefore fixing just
the bpf program to 'fix' the address to match the actual
function address when CONFIG_X86_KERNEL_IBT is enabled.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/testing/selftests/bpf/progs/get_func_ip_test.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/get_func_ip_test.c b/tools/testing/selftests/bpf/progs/get_func_ip_test.c
index a587aeca5ae0..220d56b7c1dc 100644
--- a/tools/testing/selftests/bpf/progs/get_func_ip_test.c
+++ b/tools/testing/selftests/bpf/progs/get_func_ip_test.c
@@ -2,6 +2,7 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
+#include <stdbool.h>
 
 char _license[] SEC("license") = "GPL";
 
@@ -13,6 +14,8 @@ extern const void bpf_modify_return_test __ksym;
 extern const void bpf_fentry_test6 __ksym;
 extern const void bpf_fentry_test7 __ksym;
 
+extern bool CONFIG_X86_KERNEL_IBT __kconfig __weak;
+
 __u64 test1_result = 0;
 SEC("fentry/bpf_fentry_test1")
 int BPF_PROG(test1, int a)
@@ -37,7 +40,7 @@ __u64 test3_result = 0;
 SEC("kprobe/bpf_fentry_test3")
 int test3(struct pt_regs *ctx)
 {
-	__u64 addr = bpf_get_func_ip(ctx);
+	__u64 addr = bpf_get_func_ip(ctx) - (CONFIG_X86_KERNEL_IBT ? 4 : 0);
 
 	test3_result = (const void *) addr == &bpf_fentry_test3;
 	return 0;
@@ -47,7 +50,7 @@ __u64 test4_result = 0;
 SEC("kretprobe/bpf_fentry_test4")
 int BPF_KRETPROBE(test4)
 {
-	__u64 addr = bpf_get_func_ip(ctx);
+	__u64 addr = bpf_get_func_ip(ctx) - (CONFIG_X86_KERNEL_IBT ? 4 : 0);
 
 	test4_result = (const void *) addr == &bpf_fentry_test4;
 	return 0;
-- 
2.35.3