In certain situations a program with subprograms may have a NULL
extable entry. This should not happen, and when it does, it turns a
single trap into multiple. Add a test case for further debugging and to
prevent regressions. N.b: without any other patches this can panic or
oops a kernel.
Signed-off-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
---
.../bpf/prog_tests/subprogs_extable.c | 35 +++++++++
.../bpf/progs/test_subprogs_extable.c | 71 +++++++++++++++++++
2 files changed, 106 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/subprogs_extable.c
create mode 100644 tools/testing/selftests/bpf/progs/test_subprogs_extable.c
diff --git a/tools/testing/selftests/bpf/prog_tests/subprogs_extable.c b/tools/testing/selftests/bpf/prog_tests/subprogs_extable.c
new file mode 100644
index 000000000000..18169b7eedf8
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/subprogs_extable.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+
+#include <test_progs.h>
+#include <stdbool.h>
+#include "test_subprogs_extable.skel.h"
+
+static int duration;
+
+void test_subprogs_extable(void)
+{
+ const int READ_SZ = 456;
+ struct test_subprogs_extable *skel;
+ int err;
+
+ skel = test_subprogs_extable__open();
+ if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+ return;
+
+ err = test_subprogs_extable__load(skel);
+ if (CHECK(err, "skel_load", "failed to load skeleton\n"))
+ return;
+
+ err = test_subprogs_extable__attach(skel);
+ if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+ goto cleanup;
+
+ /* trigger tracepoint */
+ ASSERT_OK(trigger_module_test_read(READ_SZ), "trigger_read");
+
+ test_subprogs_extable__detach(skel);
+
+cleanup:
+ test_subprogs_extable__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_subprogs_extable.c b/tools/testing/selftests/bpf/progs/test_subprogs_extable.c
new file mode 100644
index 000000000000..408137eaaa07
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_subprogs_extable.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 8);
+ __type(key, __u32);
+ __type(value, __u64);
+} test_array SEC(".maps");
+
+static __u64 test_cb(struct bpf_map *map, __u32 *key, __u64 *val, void *data)
+{
+ return 1;
+}
+
+static __u64 test_cb2(struct bpf_map *map, __u32 *key, __u64 *val, void *data)
+{
+ return 1;
+}
+
+static __u64 test_cb3(struct bpf_map *map, __u32 *key, __u64 *val, void *data)
+{
+ return 1;
+}
+
+SEC("fexit/bpf_testmod_return_ptr")
+int BPF_PROG(handle_fexit_ret_subprogs, int arg, struct file *ret)
+{
+ long buf = 0;
+
+ bpf_probe_read_kernel(&buf, 8, ret);
+ bpf_probe_read_kernel(&buf, 8, (char *)ret + 256);
+ *(volatile long long *)ret;
+ *(volatile int *)&ret->f_mode;
+ bpf_for_each_map_elem(&test_array, test_cb, NULL, 0);
+ return 0;
+}
+
+SEC("fexit/bpf_testmod_return_ptr")
+int BPF_PROG(handle_fexit_ret_subprogs2, int arg, struct file *ret)
+{
+ long buf = 0;
+
+ bpf_probe_read_kernel(&buf, 8, ret);
+ bpf_probe_read_kernel(&buf, 8, (char *)ret + 256);
+ *(volatile long long *)ret;
+ *(volatile int *)&ret->f_mode;
+ bpf_for_each_map_elem(&test_array, test_cb2, NULL, 0);
+ return 0;
+}
+
+SEC("fexit/bpf_testmod_return_ptr")
+int BPF_PROG(handle_fexit_ret_subprogs3, int arg, struct file *ret)
+{
+ long buf = 0;
+
+ bpf_probe_read_kernel(&buf, 8, ret);
+ bpf_probe_read_kernel(&buf, 8, (char *)ret + 256);
+ *(volatile long long *)ret;
+ *(volatile int *)&ret->f_mode;
+ bpf_for_each_map_elem(&test_array, test_cb3, NULL, 0);
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.25.1
