selftests/bpf: Ksyms_btf to test typed ksyms

Selftests for typed ksyms. Tests two types of ksyms: one is a struct,
the other is a plain int. This tests two paths in the kernel. Struct
ksyms will be converted into PTR_TO_BTF_ID by the verifier while int
typed ksyms will be converted into PTR_TO_MEM.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-4-haoluo@google.com

1 files changed, 13 insertions, 25 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms.c b/tools/testing/selftests/bpf/prog_tests/ksyms.c
index b771804b2342..b295969b263b 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms.c
@@ -7,40 +7,28 @@
 
 static int duration;
 
-static __u64 kallsyms_find(const char *sym)
-{
-	char type, name[500];
-	__u64 addr, res = 0;
-	FILE *f;
-
-	f = fopen("/proc/kallsyms", "r");
-	if (CHECK(!f, "kallsyms_fopen", "failed to open: %d\n", errno))
-		return 0;
-
-	while (fscanf(f, "%llx %c %499s%*[^\n]\n", &addr, &type, name) > 0) {
-		if (strcmp(name, sym) == 0) {
-			res = addr;
-			goto out;
-		}
-	}
-
-	CHECK(false, "not_found", "symbol %s not found\n", sym);
-out:
-	fclose(f);
-	return res;
-}
-
 void test_ksyms(void)
 {
-	__u64 per_cpu_start_addr = kallsyms_find("__per_cpu_start");
-	__u64 link_fops_addr = kallsyms_find("bpf_link_fops");
 	const char *btf_path = "/sys/kernel/btf/vmlinux";
 	struct test_ksyms *skel;
 	struct test_ksyms__data *data;
+	__u64 link_fops_addr, per_cpu_start_addr;
 	struct stat st;
 	__u64 btf_size;
 	int err;
 
+	err = kallsyms_find("bpf_link_fops", &link_fops_addr);
+	if (CHECK(err == -EINVAL, "kallsyms_fopen", "failed to open: %d\n", errno))
+		return;
+	if (CHECK(err == -ENOENT, "ksym_find", "symbol 'bpf_link_fops' not found\n"))
+		return;
+
+	err = kallsyms_find("__per_cpu_start", &per_cpu_start_addr);
+	if (CHECK(err == -EINVAL, "kallsyms_fopen", "failed to open: %d\n", errno))
+		return;
+	if (CHECK(err == -ENOENT, "ksym_find", "symbol 'per_cpu_start' not found\n"))
+		return;
+
 	if (CHECK(stat(btf_path, &st), "stat_btf", "err %d\n", errno))
 		return;
 	btf_size = st.st_size;