On 3/10/22 12:22 AM, Namhyung Kim wrote:
Add a test case for stacktrace with skip > 0 using a small sized
buffer. It didn't support skipping entries greater than or equal to
the size of buffer and filled the skipped part with 0.
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
.../bpf/prog_tests/stacktrace_map_skip.c | 72 ++++++++++++++++
.../selftests/bpf/progs/stacktrace_map_skip.c | 82 +++++++++++++++++++
2 files changed, 154 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c
create mode 100644 tools/testing/selftests/bpf/progs/stacktrace_map_skip.c
diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c
new file mode 100644
index 000000000000..bcb244aa3c78
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "stacktrace_map_skip.skel.h"
+
+#define TEST_STACK_DEPTH 2
+
+void test_stacktrace_map_skip(void)
+{
+ struct stacktrace_map_skip *skel;
+ int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
+ int err, stack_trace_len;
+ __u32 key, val, duration = 0;
+
+ skel = stacktrace_map_skip__open_and_load();
+ if (CHECK(!skel, "skel_open_and_load", "skeleton open failed\n"))
+ return;
Please use ASSERT_* macros instead of CHECK* macros.
You can see other prog_tests/*.c files for examples.
+
+ /* find map fds */
+ control_map_fd = bpf_map__fd(skel->maps.control_map);
+ if (CHECK_FAIL(control_map_fd < 0))
+ goto out;
+
+ stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
+ if (CHECK_FAIL(stackid_hmap_fd < 0))
+ goto out;
+
+ stackmap_fd = bpf_map__fd(skel->maps.stackmap);
+ if (CHECK_FAIL(stackmap_fd < 0))
+ goto out;
+
+ stack_amap_fd = bpf_map__fd(skel->maps.stack_amap);
+ if (CHECK_FAIL(stack_amap_fd < 0))
+ goto out;
+
+ err = stacktrace_map_skip__attach(skel);
+ if (CHECK(err, "skel_attach", "skeleton attach failed\n"))
+ goto out;
+
+ /* give some time for bpf program run */
+ sleep(1);
+
+ /* disable stack trace collection */
+ key = 0;
+ val = 1;
+ bpf_map_update_elem(control_map_fd, &key, &val, 0);
+
+ /* for every element in stackid_hmap, we can find a corresponding one
+ * in stackmap, and vise versa.
+ */
+ err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
+ if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
+ "err %d errno %d\n", err, errno))
+ goto out;
+
+ err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
+ if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
+ "err %d errno %d\n", err, errno))
+ goto out;
+
+ stack_trace_len = TEST_STACK_DEPTH * sizeof(__u64);
+ err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
+ if (CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
+ "err %d errno %d\n", err, errno))
+ goto out;
+
+ if (CHECK(skel->bss->failed, "check skip",
+ "failed to skip some depth: %d", skel->bss->failed))
+ goto out;
+
+out:
+ stacktrace_map_skip__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c b/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c
new file mode 100644
index 000000000000..323248b17ae4
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+#define TEST_STACK_DEPTH 2
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} control_map SEC(".maps");
You can use a global variable for this.
The global variable can be assigned a value (if needed, e.g., non-zero)
before skeleton open and load.
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 16384);
+ __type(key, __u32);
+ __type(value, __u32);
+} stackid_hmap SEC(".maps");
+
+typedef __u64 stack_trace_t[TEST_STACK_DEPTH];
+
+struct {
+ __uint(type, BPF_MAP_TYPE_STACK_TRACE);
+ __uint(max_entries, 16384);
+ __type(key, __u32);
+ __type(value, stack_trace_t);
+} stackmap SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 16384);
+ __type(key, __u32);
+ __type(value, stack_trace_t);
+} stack_amap SEC(".maps");
+
+/* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
+struct sched_switch_args {
+ unsigned long long pad;
+ char prev_comm[TASK_COMM_LEN];
+ int prev_pid;
+ int prev_prio;
+ long long prev_state;
+ char next_comm[TASK_COMM_LEN];
+ int next_pid;
+ int next_prio;
+};
You can use this structure in vmlinux.h instead of the above:
struct trace_event_raw_sched_switch {
struct trace_entry ent;
char prev_comm[16];
pid_t prev_pid;
int prev_prio;
long int prev_state;
char next_comm[16];
pid_t next_pid;
int next_prio;
char __data[0];
};
+
+int failed = 0;
+
+SEC("tracepoint/sched/sched_switch")
+int oncpu(struct sched_switch_args *ctx)
+{
+ __u32 max_len = TEST_STACK_DEPTH * sizeof(__u64);
+ __u32 key = 0, val = 0, *value_p;
+ __u64 *stack_p;
+
+ value_p = bpf_map_lookup_elem(&control_map, &key);
+ if (value_p && *value_p)
+ return 0; /* skip if non-zero *value_p */
+
+ /* it should allow skipping whole buffer size entries */
+ key = bpf_get_stackid(ctx, &stackmap, TEST_STACK_DEPTH);
+ if ((int)key >= 0) {
+ /* The size of stackmap and stack_amap should be the same */
+ bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
+ stack_p = bpf_map_lookup_elem(&stack_amap, &key);
+ if (stack_p) {
+ bpf_get_stack(ctx, stack_p, max_len, TEST_STACK_DEPTH);
+ /* it wrongly skipped all the entries and filled zero */
+ if (stack_p[0] == 0)
+ failed = 1;
+ }
+ } else if ((int)key == -14/*EFAULT*/) {
+ /* old kernel doesn't support skipping that many entries */
+ failed = 2;
The selftest is supposed to run with the kernel in the same code base.
So it is okay to skip the above 'if' test and just set failed = 2.
+ }
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
