[PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data

["Thiébaud Weksteen" <tweek@google.com>]

Commit 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu
data") added test_global_percpu_data.c to LSKELS_EXTRA. Later, in commit
1ed2294b31fc ("selftests/bpf: Test verifier log for global percpu data")
two verifier failure tests were added (verifier_strncmp and
verifier_snprintf), both marked as non-autoload (SEC("?kprobe")).

When bpftool generates light skeletons, non-autoloaded programs are
skipped during loading, causing the loader program to store subsequent
program FDs into incorrect skeleton struct fields (e.g. dump_percpu_data's
FD was stored into verifier_strncmp's descriptor).

Move the two verifier failure tests to a dedicated test file,
test_global_percpu_data_failure.c, and run them via RUN_TESTS in
global_data_init.c. This leaves test_global_percpu_data.c with only
autoloaded programs, ensuring the light skeleton can be generated cleanly
and correctly.

Fixes: 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu data")
Fixes: 1ed2294b31fc ("selftests/bpf: Test verifier log for global percpu data")
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
---
 .../bpf/prog_tests/global_data_init.c         |  3 +-
 .../bpf/progs/test_global_percpu_data.c       | 23 --------------
 .../progs/test_global_percpu_data_failure.c   | 30 +++++++++++++++++++
 3 files changed, 32 insertions(+), 24 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c

diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
index 7c539cbcf3a1..dbb7de534f7d 100644
--- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c
+++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
@@ -3,6 +3,7 @@
 #include "bpf/libbpf_internal.h"
 #include "test_global_percpu_data.skel.h"
 #include "test_global_percpu_data.lskel.h"
+#include "test_global_percpu_data_failure.skel.h"
 
 void test_global_data_init(void)
 {
@@ -372,7 +373,7 @@ static void test_global_percpu_data_rdonly_direct_write(void)
 
 static void test_global_percpu_data_verifier_log(void)
 {
-	RUN_TESTS(test_global_percpu_data);
+	RUN_TESTS(test_global_percpu_data_failure);
 }
 
 static void test_global_percpu_data_iter(void)
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
index 2765cd46e9af..bc748df4a6cc 100644
--- a/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data.c
@@ -42,29 +42,6 @@ int update_percpu_data(void *ctx)
 	return 0;
 }
 
-static const char fmt[] SEC(".percpu.fmt") = "data %d\n";
-
-SEC("?kprobe")
-__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
-int verifier_strncmp(void *ctx)
-{
-	return bpf_strncmp("test", 5, fmt);
-}
-
-SEC("?kprobe")
-__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
-int verifier_snprintf(void *ctx)
-{
-	u64 args[] = { data };
-	char buf[128];
-	int len;
-
-	len = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));
-	if (len > 0)
-		bpf_printk("snprintf: %s\n", buf);
-	return 0;
-}
-
 volatile const __u32 num_cpus = 0;
 volatile const int num_off;
 volatile const int elem_sz;
diff --git a/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
new file mode 100644
index 000000000000..3a823acb42d7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_percpu_data_failure.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+int data SEC(".percpu") = -1;
+static const char fmt[] SEC(".percpu.fmt") = "data %d\n";
+
+SEC("?kprobe")
+__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
+int verifier_strncmp(void *ctx)
+{
+	return bpf_strncmp("test", 5, fmt);
+}
+
+SEC("?kprobe")
+__failure __msg("R{{[0-9]+}} points to percpu_array map which cannot be used as const string")
+int verifier_snprintf(void *ctx)
+{
+	u64 args[] = { data };
+	char buf[128];
+	int len;
+
+	len = bpf_snprintf(buf, sizeof(buf), fmt, args, sizeof(args));
+	if (len > 0)
+		bpf_printk("snprintf: %s\n", buf);
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.55.0.979.g7e5102b832-goog