// 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 <linux/perf_event.h>
  #include <linux/ptrace.h>
  #include <linux/bpf.h>

  #include <bpf/bpf.h>

  #include <bpf/libbpf.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 map_fd;

  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 freq, struct bpf_program *prog,
  			  struct bpf_link *links[])

  {

  	int i, pmu_fd;

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

  					    -1 /* group_fd */, 0 /* flags */);

  		if (pmu_fd < 0) {

  			fprintf(stderr, "ERROR: Initializing perf sampling
  ");
  			return 1;
  		}

  		links[i] = bpf_program__attach_perf_event(prog, pmu_fd);

  		if (libbpf_get_error(links[i])) {

  			fprintf(stderr, "ERROR: Attach perf event
  ");
  			links[i] = NULL;
  			close(pmu_fd);
  			return 1;
  		}

  	}
  
  	return 0;
  }

  static void sampling_end(struct bpf_link *links[])

  {
  	int i;
  
  	for (i = 0; i < nr_cpus; i++)

  		bpf_link__destroy(links[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);

  	exit(0);
  }
  
  int main(int argc, char **argv)
  {

  	int opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS, error = 1;
  	struct bpf_object *obj = NULL;
  	struct bpf_program *prog;
  	struct bpf_link **links;

  	char filename[256];

  
  	/* 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_ONLN);
  	links = calloc(nr_cpus, sizeof(struct bpf_link *));
  	if (!links) {
  		fprintf(stderr, "ERROR: malloc of links
  ");
  		goto cleanup;

  	}

  	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);

  	obj = bpf_object__open_file(filename, NULL);

  	if (libbpf_get_error(obj)) {

  		fprintf(stderr, "ERROR: opening BPF object file failed
  ");
  		obj = NULL;
  		goto cleanup;
  	}
  
  	prog = bpf_object__find_program_by_name(obj, "do_sample");
  	if (!prog) {
  		fprintf(stderr, "ERROR: finding a prog in obj file failed
  ");
  		goto cleanup;

  	}

  
  	/* load BPF program */
  	if (bpf_object__load(obj)) {
  		fprintf(stderr, "ERROR: loading BPF object file failed
  ");
  		goto cleanup;
  	}
  
  	map_fd = bpf_object__find_map_fd_by_name(obj, "ip_map");
  	if (map_fd < 0) {
  		fprintf(stderr, "ERROR: finding a map in obj file failed
  ");
  		goto cleanup;
  	}

  	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(freq, prog, links) != 0)
  		goto cleanup;

  	sleep(secs);

  	error = 0;

  cleanup:
  	sampling_end(links);

  	/* output sample counts */

  	if (!error)
  		print_ip_map(map_fd);

  	free(links);
  	bpf_object__close(obj);
  	return error;

  }