1 /*
2 * sampleip: sample instruction pointer and frequency count in a BPF map.
3 *
4 * Copyright 2016 Netflix, Inc.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of version 2 of the GNU General Public
8 * License as published by the Free Software Foundation.
9 */
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <stdio.h>
13 #include <unistd.h>
14 #include <errno.h>
15 #include <signal.h>
16 #include <string.h>
17 #include <assert.h>
18 #include <linux/perf_event.h>
19 #include <linux/ptrace.h>
20 #include <linux/bpf.h>
21 #include <sys/ioctl.h>
22 #include "libbpf.h"
23 #include "bpf_load.h"
24 #include "perf-sys.h"
25 #include "trace_helpers.h"
26
27 #define DEFAULT_FREQ 99
28 #define DEFAULT_SECS 5
29 #define MAX_IPS 8192
30 #define PAGE_OFFSET 0xffff880000000000
31
32 static int nr_cpus;
33
usage(void)34 static void usage(void)
35 {
36 printf("USAGE: sampleip [-F freq] [duration]\n");
37 printf(" -F freq # sample frequency (Hertz), default 99\n");
38 printf(" duration # sampling duration (seconds), default 5\n");
39 }
40
sampling_start(int * pmu_fd,int freq)41 static int sampling_start(int *pmu_fd, int freq)
42 {
43 int i;
44
45 struct perf_event_attr pe_sample_attr = {
46 .type = PERF_TYPE_SOFTWARE,
47 .freq = 1,
48 .sample_period = freq,
49 .config = PERF_COUNT_SW_CPU_CLOCK,
50 .inherit = 1,
51 };
52
53 for (i = 0; i < nr_cpus; i++) {
54 pmu_fd[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
55 -1 /* group_fd */, 0 /* flags */);
56 if (pmu_fd[i] < 0) {
57 fprintf(stderr, "ERROR: Initializing perf sampling\n");
58 return 1;
59 }
60 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
61 prog_fd[0]) == 0);
62 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
63 }
64
65 return 0;
66 }
67
sampling_end(int * pmu_fd)68 static void sampling_end(int *pmu_fd)
69 {
70 int i;
71
72 for (i = 0; i < nr_cpus; i++)
73 close(pmu_fd[i]);
74 }
75
76 struct ipcount {
77 __u64 ip;
78 __u32 count;
79 };
80
81 /* used for sorting */
82 struct ipcount counts[MAX_IPS];
83
count_cmp(const void * p1,const void * p2)84 static int count_cmp(const void *p1, const void *p2)
85 {
86 return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count;
87 }
88
print_ip_map(int fd)89 static void print_ip_map(int fd)
90 {
91 struct ksym *sym;
92 __u64 key, next_key;
93 __u32 value;
94 int i, max;
95
96 printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT");
97
98 /* fetch IPs and counts */
99 key = 0, i = 0;
100 while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
101 bpf_map_lookup_elem(fd, &next_key, &value);
102 counts[i].ip = next_key;
103 counts[i++].count = value;
104 key = next_key;
105 }
106 max = i;
107
108 /* sort and print */
109 qsort(counts, max, sizeof(struct ipcount), count_cmp);
110 for (i = 0; i < max; i++) {
111 if (counts[i].ip > PAGE_OFFSET) {
112 sym = ksym_search(counts[i].ip);
113 printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
114 counts[i].count);
115 } else {
116 printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)",
117 counts[i].count);
118 }
119 }
120
121 if (max == MAX_IPS) {
122 printf("WARNING: IP hash was full (max %d entries); ", max);
123 printf("may have dropped samples\n");
124 }
125 }
126
int_exit(int sig)127 static void int_exit(int sig)
128 {
129 printf("\n");
130 print_ip_map(map_fd[0]);
131 exit(0);
132 }
133
main(int argc,char ** argv)134 int main(int argc, char **argv)
135 {
136 char filename[256];
137 int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
138
139 /* process arguments */
140 while ((opt = getopt(argc, argv, "F:h")) != -1) {
141 switch (opt) {
142 case 'F':
143 freq = atoi(optarg);
144 break;
145 case 'h':
146 default:
147 usage();
148 return 0;
149 }
150 }
151 if (argc - optind == 1)
152 secs = atoi(argv[optind]);
153 if (freq == 0 || secs == 0) {
154 usage();
155 return 1;
156 }
157
158 /* initialize kernel symbol translation */
159 if (load_kallsyms()) {
160 fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
161 return 2;
162 }
163
164 /* create perf FDs for each CPU */
165 nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
166 pmu_fd = malloc(nr_cpus * sizeof(int));
167 if (pmu_fd == NULL) {
168 fprintf(stderr, "ERROR: malloc of pmu_fd\n");
169 return 1;
170 }
171
172 /* load BPF program */
173 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
174 if (load_bpf_file(filename)) {
175 fprintf(stderr, "ERROR: loading BPF program (errno %d):\n",
176 errno);
177 if (strcmp(bpf_log_buf, "") == 0)
178 fprintf(stderr, "Try: ulimit -l unlimited\n");
179 else
180 fprintf(stderr, "%s", bpf_log_buf);
181 return 1;
182 }
183 signal(SIGINT, int_exit);
184 signal(SIGTERM, int_exit);
185
186 /* do sampling */
187 printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
188 freq, secs);
189 if (sampling_start(pmu_fd, freq) != 0)
190 return 1;
191 sleep(secs);
192 sampling_end(pmu_fd);
193 free(pmu_fd);
194
195 /* output sample counts */
196 print_ip_map(map_fd[0]);
197
198 return 0;
199 }
200
