// SPDX-License-Identifier: GPL-2.0-only

  /*
   * sampleip: sample instruction pointer and frequency count in a BPF map.
   *
   * Copyright 2016 Netflix, Inc.

   */
  #include <stdio.h>
  #include <stdlib.h>

  #include <unistd.h>
  #include <errno.h>
  #include <signal.h>
  #include <string.h>
  #include <assert.h>
  #include <linux/perf_event.h>
  #include <linux/ptrace.h>
  #include <linux/bpf.h>
  #include <sys/ioctl.h>
  #include "libbpf.h"
  #include "bpf_load.h"

  #include "perf-sys.h"

  #include "trace_helpers.h"

  
  #define DEFAULT_FREQ	99
  #define DEFAULT_SECS	5
  #define MAX_IPS		8192
  #define PAGE_OFFSET	0xffff880000000000
  
  static int nr_cpus;
  
  static void usage(void)
  {
  	printf("USAGE: sampleip [-F freq] [duration]
  ");
  	printf("       -F freq    # sample frequency (Hertz), default 99
  ");
  	printf("       duration   # sampling duration (seconds), default 5
  ");
  }
  
  static int sampling_start(int *pmu_fd, int freq)
  {
  	int i;
  
  	struct perf_event_attr pe_sample_attr = {
  		.type = PERF_TYPE_SOFTWARE,
  		.freq = 1,
  		.sample_period = freq,
  		.config = PERF_COUNT_SW_CPU_CLOCK,
  		.inherit = 1,
  	};
  
  	for (i = 0; i < nr_cpus; i++) {

  		pmu_fd[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,

  					    -1 /* group_fd */, 0 /* flags */);
  		if (pmu_fd[i] < 0) {
  			fprintf(stderr, "ERROR: Initializing perf sampling
  ");
  			return 1;
  		}
  		assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
  			     prog_fd[0]) == 0);
  		assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
  	}
  
  	return 0;
  }
  
  static void sampling_end(int *pmu_fd)
  {
  	int i;
  
  	for (i = 0; i < nr_cpus; i++)
  		close(pmu_fd[i]);
  }
  
  struct ipcount {
  	__u64 ip;
  	__u32 count;
  };
  
  /* used for sorting */
  struct ipcount counts[MAX_IPS];
  
  static int count_cmp(const void *p1, const void *p2)
  {
  	return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count;
  }
  
  static void print_ip_map(int fd)
  {
  	struct ksym *sym;
  	__u64 key, next_key;
  	__u32 value;
  	int i, max;
  
  	printf("%-19s %-32s %s
  ", "ADDR", "KSYM", "COUNT");
  
  	/* fetch IPs and counts */
  	key = 0, i = 0;

  	while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  		bpf_map_lookup_elem(fd, &next_key, &value);

  		counts[i].ip = next_key;
  		counts[i++].count = value;
  		key = next_key;
  	}
  	max = i;
  
  	/* sort and print */
  	qsort(counts, max, sizeof(struct ipcount), count_cmp);
  	for (i = 0; i < max; i++) {
  		if (counts[i].ip > PAGE_OFFSET) {
  			sym = ksym_search(counts[i].ip);

  			if (!sym) {
  				printf("ksym not found. Is kallsyms loaded?
  ");
  				continue;
  			}

  			printf("0x%-17llx %-32s %u
  ", counts[i].ip, sym->name,
  			       counts[i].count);
  		} else {
  			printf("0x%-17llx %-32s %u
  ", counts[i].ip, "(user)",
  			       counts[i].count);
  		}
  	}
  
  	if (max == MAX_IPS) {
  		printf("WARNING: IP hash was full (max %d entries); ", max);
  		printf("may have dropped samples
  ");
  	}
  }
  
  static void int_exit(int sig)
  {
  	printf("
  ");
  	print_ip_map(map_fd[0]);
  	exit(0);
  }
  
  int main(int argc, char **argv)
  {
  	char filename[256];
  	int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
  
  	/* process arguments */
  	while ((opt = getopt(argc, argv, "F:h")) != -1) {
  		switch (opt) {
  		case 'F':
  			freq = atoi(optarg);
  			break;
  		case 'h':
  		default:
  			usage();
  			return 0;
  		}
  	}
  	if (argc - optind == 1)
  		secs = atoi(argv[optind]);
  	if (freq == 0 || secs == 0) {
  		usage();
  		return 1;
  	}
  
  	/* initialize kernel symbol translation */
  	if (load_kallsyms()) {
  		fprintf(stderr, "ERROR: loading /proc/kallsyms
  ");
  		return 2;
  	}
  
  	/* create perf FDs for each CPU */
  	nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
  	pmu_fd = malloc(nr_cpus * sizeof(int));
  	if (pmu_fd == NULL) {
  		fprintf(stderr, "ERROR: malloc of pmu_fd
  ");
  		return 1;
  	}
  
  	/* load BPF program */
  	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  	if (load_bpf_file(filename)) {
  		fprintf(stderr, "ERROR: loading BPF program (errno %d):
  ",
  			errno);
  		if (strcmp(bpf_log_buf, "") == 0)
  			fprintf(stderr, "Try: ulimit -l unlimited
  ");
  		else
  			fprintf(stderr, "%s", bpf_log_buf);
  		return 1;
  	}
  	signal(SIGINT, int_exit);

  	signal(SIGTERM, int_exit);

  
  	/* do sampling */
  	printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.
  ",
  	       freq, secs);
  	if (sampling_start(pmu_fd, freq) != 0)
  		return 1;
  	sleep(secs);
  	sampling_end(pmu_fd);
  	free(pmu_fd);
  
  	/* output sample counts */
  	print_ip_map(map_fd[0]);
  
  	return 0;
  }