v4.19.13 snapshot.
diff --git a/samples/bpf/trace_event_kern.c b/samples/bpf/trace_event_kern.c
new file mode 100644
index 0000000..7068fbd
--- /dev/null
+++ b/samples/bpf/trace_event_kern.c
@@ -0,0 +1,79 @@
+/* Copyright (c) 2016 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <linux/ptrace.h>
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/bpf_perf_event.h>
+#include <uapi/linux/perf_event.h>
+#include "bpf_helpers.h"
+
+struct key_t {
+ char comm[TASK_COMM_LEN];
+ u32 kernstack;
+ u32 userstack;
+};
+
+struct bpf_map_def SEC("maps") counts = {
+ .type = BPF_MAP_TYPE_HASH,
+ .key_size = sizeof(struct key_t),
+ .value_size = sizeof(u64),
+ .max_entries = 10000,
+};
+
+struct bpf_map_def SEC("maps") stackmap = {
+ .type = BPF_MAP_TYPE_STACK_TRACE,
+ .key_size = sizeof(u32),
+ .value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
+ .max_entries = 10000,
+};
+
+#define KERN_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
+#define USER_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP | BPF_F_USER_STACK)
+
+SEC("perf_event")
+int bpf_prog1(struct bpf_perf_event_data *ctx)
+{
+ char time_fmt1[] = "Time Enabled: %llu, Time Running: %llu";
+ char time_fmt2[] = "Get Time Failed, ErrCode: %d";
+ char addr_fmt[] = "Address recorded on event: %llx";
+ char fmt[] = "CPU-%d period %lld ip %llx";
+ u32 cpu = bpf_get_smp_processor_id();
+ struct bpf_perf_event_value value_buf;
+ struct key_t key;
+ u64 *val, one = 1;
+ int ret;
+
+ if (ctx->sample_period < 10000)
+ /* ignore warmup */
+ return 0;
+ bpf_get_current_comm(&key.comm, sizeof(key.comm));
+ key.kernstack = bpf_get_stackid(ctx, &stackmap, KERN_STACKID_FLAGS);
+ key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
+ if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
+ bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,
+ PT_REGS_IP(&ctx->regs));
+ return 0;
+ }
+
+ ret = bpf_perf_prog_read_value(ctx, (void *)&value_buf, sizeof(struct bpf_perf_event_value));
+ if (!ret)
+ bpf_trace_printk(time_fmt1, sizeof(time_fmt1), value_buf.enabled, value_buf.running);
+ else
+ bpf_trace_printk(time_fmt2, sizeof(time_fmt2), ret);
+
+ if (ctx->addr != 0)
+ bpf_trace_printk(addr_fmt, sizeof(addr_fmt), ctx->addr);
+
+ val = bpf_map_lookup_elem(&counts, &key);
+ if (val)
+ (*val)++;
+ else
+ bpf_map_update_elem(&counts, &key, &one, BPF_NOEXIST);
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";