v4.19.13 snapshot.
diff --git a/samples/bpf/tracex2_user.c b/samples/bpf/tracex2_user.c
new file mode 100644
index 0000000..1a81e6a
--- /dev/null
+++ b/samples/bpf/tracex2_user.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <linux/bpf.h>
+#include <string.h>
+#include <sys/resource.h>
+
+#include <bpf/bpf.h>
+#include "bpf_load.h"
+#include "bpf_util.h"
+
+#define MAX_INDEX 64
+#define MAX_STARS 38
+
+static void stars(char *str, long val, long max, int width)
+{
+ int i;
+
+ for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
+ str[i] = '*';
+ if (val > max)
+ str[i - 1] = '+';
+ str[i] = '\0';
+}
+
+struct task {
+ char comm[16];
+ __u64 pid_tgid;
+ __u64 uid_gid;
+};
+
+struct hist_key {
+ struct task t;
+ __u32 index;
+};
+
+#define SIZE sizeof(struct task)
+
+static void print_hist_for_pid(int fd, void *task)
+{
+ unsigned int nr_cpus = bpf_num_possible_cpus();
+ struct hist_key key = {}, next_key;
+ long values[nr_cpus];
+ char starstr[MAX_STARS];
+ long value;
+ long data[MAX_INDEX] = {};
+ int max_ind = -1;
+ long max_value = 0;
+ int i, ind;
+
+ while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
+ if (memcmp(&next_key, task, SIZE)) {
+ key = next_key;
+ continue;
+ }
+ bpf_map_lookup_elem(fd, &next_key, values);
+ value = 0;
+ for (i = 0; i < nr_cpus; i++)
+ value += values[i];
+ ind = next_key.index;
+ data[ind] = value;
+ if (value && ind > max_ind)
+ max_ind = ind;
+ if (value > max_value)
+ max_value = value;
+ key = next_key;
+ }
+
+ printf(" syscall write() stats\n");
+ printf(" byte_size : count distribution\n");
+ for (i = 1; i <= max_ind + 1; i++) {
+ stars(starstr, data[i - 1], max_value, MAX_STARS);
+ printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
+ (1l << i) >> 1, (1l << i) - 1, data[i - 1],
+ MAX_STARS, starstr);
+ }
+}
+
+static void print_hist(int fd)
+{
+ struct hist_key key = {}, next_key;
+ static struct task tasks[1024];
+ int task_cnt = 0;
+ int i;
+
+ while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
+ int found = 0;
+
+ for (i = 0; i < task_cnt; i++)
+ if (memcmp(&tasks[i], &next_key, SIZE) == 0)
+ found = 1;
+ if (!found)
+ memcpy(&tasks[task_cnt++], &next_key, SIZE);
+ key = next_key;
+ }
+
+ for (i = 0; i < task_cnt; i++) {
+ printf("\npid %d cmd %s uid %d\n",
+ (__u32) tasks[i].pid_tgid,
+ tasks[i].comm,
+ (__u32) tasks[i].uid_gid);
+ print_hist_for_pid(fd, &tasks[i]);
+ }
+
+}
+
+static void int_exit(int sig)
+{
+ print_hist(map_fd[1]);
+ exit(0);
+}
+
+int main(int ac, char **argv)
+{
+ struct rlimit r = {1024*1024, RLIM_INFINITY};
+ char filename[256];
+ long key, next_key, value;
+ FILE *f;
+ int i;
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+ if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+ perror("setrlimit(RLIMIT_MEMLOCK)");
+ return 1;
+ }
+
+ signal(SIGINT, int_exit);
+ signal(SIGTERM, int_exit);
+
+ /* start 'ping' in the background to have some kfree_skb events */
+ f = popen("ping -c5 localhost", "r");
+ (void) f;
+
+ /* start 'dd' in the background to have plenty of 'write' syscalls */
+ f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
+ (void) f;
+
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ for (i = 0; i < 5; i++) {
+ key = 0;
+ while (bpf_map_get_next_key(map_fd[0], &key, &next_key) == 0) {
+ bpf_map_lookup_elem(map_fd[0], &next_key, &value);
+ printf("location 0x%lx count %ld\n", next_key, value);
+ key = next_key;
+ }
+ if (key)
+ printf("\n");
+ sleep(1);
+ }
+ print_hist(map_fd[1]);
+
+ return 0;
+}