On 9/14/22 5:36 AM, Dave Marchevsky wrote:
Add a test_ringbuf_map_key test prog, borrowing heavily from extant
test_ringbuf.c. The program tries to use the result of
bpf_ringbuf_reserve as map_key, which was not possible before previouis
commits in this series. The test runner added to prog_tests/ringbuf.c
verifies that the program loads and does basic sanity checks to confirm
that it runs as expected.
Also, refactor test_ringbuf such that runners for existing test_ringbuf
and newly-added test_ringbuf_map_key are subtests of 'ringbuf' top-level
test.
Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
---
v1->v2: lore.kernel.org/bpf/20220912101106.2765921-1-davemarchevsky@xxxxxx
* Actually run the program instead of just loading (Yonghong)
* Add a bpf_map_update_elem call to the test (Yonghong)
* Refactor runner such that existing test and newly-added test are
subtests of 'ringbuf' top-level test (Yonghong)
* Remove unused globals in test prog (Yonghong)
tools/testing/selftests/bpf/Makefile | 8 ++-
.../selftests/bpf/prog_tests/ringbuf.c | 63 ++++++++++++++++-
.../bpf/progs/test_ringbuf_map_key.c | 70 +++++++++++++++++++
3 files changed, 137 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c
[...]
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c b/tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c
new file mode 100644
index 000000000000..495f85c6e120
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct sample {
+ int pid;
+ int seq;
+ long value;
+ char comm[16];
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_RINGBUF);
+ __uint(max_entries, 4096);
+} ringbuf SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 1000);
+ __type(key, struct sample);
+ __type(value, int);
+} hash_map SEC(".maps");
+
+/* inputs */
+int pid = 0;
+
+/* inner state */
+long seq = 0;
+
+SEC("fentry/" SYS_PREFIX "sys_getpgid")
+int test_ringbuf_mem_map_key(void *ctx)
+{
+ int cur_pid = bpf_get_current_pid_tgid() >> 32;
+ struct sample *sample, sample_copy;
+ int *lookup_val;
+
+ if (cur_pid != pid)
+ return 0;
+
+ sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
+ if (!sample)
+ return 0;
+
+ sample->pid = pid;
+ bpf_get_current_comm(sample->comm, sizeof(sample->comm));
+ sample->seq = ++seq;
+ sample->value = 42;
+
+ /* test using 'sample' (PTR_TO_MEM | MEM_ALLOC) as map key arg
+ */
+ lookup_val = (int *)bpf_map_lookup_elem(&hash_map, sample);
+
+ /* memcpy is necessary so that verifier doesn't complain with:
+ * verifier internal error: more than one arg with ref_obj_id R3
+ * when trying to do bpf_map_update_elem(&hash_map, sample, &sample->seq, BPF_ANY);
+ *
+ * Since bpf_map_lookup_elem above uses 'sample' as key, test using
+ * sample field as value below
+ */
If I understand correctly, the above error is due to the following
verifier code:
if (reg->ref_obj_id) {
if (meta->ref_obj_id) {
verbose(env, "verifier internal error: more
than one arg with ref_obj_id R%d %u %u\n",
regno, reg->ref_obj_id,
meta->ref_obj_id);
return -EFAULT;
}
meta->ref_obj_id = reg->ref_obj_id;
}
So this is an internal error. So normally this should not happen.
Could you investigate and fix the issue?
+ __builtin_memcpy(&sample_copy, sample, sizeof(struct sample));
+ bpf_map_update_elem(&hash_map, &sample_copy, &sample->seq, BPF_ANY);
+
+ bpf_ringbuf_submit(sample, 0);
+ return 0;
+}
