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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235// 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
static int map_fd;static int nr_cpus;static long _text_addr;
static void usage(void){ printf("USAGE: sampleip [-F freq] [duration]\n"); printf(" -F freq # sample frequency (Hertz), default 99\n"); printf(" duration # sampling duration (seconds), default 5\n");}
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\n"); return 1; } links[i] = bpf_program__attach_perf_event(prog, pmu_fd); if (libbpf_get_error(links[i])) { fprintf(stderr, "ERROR: Attach perf event\n"); 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\n", "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 > _text_addr) { sym = ksym_search(counts[i].ip); if (!sym) { printf("ksym not found. Is kallsyms loaded?\n"); continue; }
printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name, counts[i].count); } else { printf("0x%-17llx %-32s %u\n", 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\n"); }}
static void int_exit(int sig){ printf("\n"); 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\n"); return 2; }
/* used to determine whether the address is kernel space */ _text_addr = ksym_get_addr("_text"); if (!_text_addr) { fprintf(stderr, "ERROR: no '_text' in /proc/kallsyms\n"); return 3; }
/* 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\n"); 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\n"); 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\n"); goto cleanup; }
/* load BPF program */ if (bpf_object__load(obj)) { fprintf(stderr, "ERROR: loading BPF object file failed\n"); 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\n"); goto cleanup; }
signal(SIGINT, int_exit); signal(SIGTERM, int_exit);
/* do sampling */ printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n", 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;}