cregit-Linux how code gets into the kernel

Release 4.14 samples/bpf/sampleip_user.c

Directory: samples/bpf
/*
 * sampleip: sample instruction pointer and frequency count in a BPF map.
 *
 * Copyright 2016 Netflix, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#include <stdio.h>
#include <stdlib.h>
#include <stdio.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"


#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]\n"); printf(" -F freq # sample frequency (Hertz), default 99\n"); printf(" duration # sampling duration (seconds), default 5\n"); }

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Brendan Gregg23100.00%1100.00%
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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\n"); 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; }

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Brendan Gregg14699.32%150.00%
Joe Stringer10.68%150.00%
Total147100.00%2100.00%


static void sampling_end(int *pmu_fd) { int i; for (i = 0; i < nr_cpus; i++) close(pmu_fd[i]); }

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Brendan Gregg34100.00%1100.00%
Total34100.00%1100.00%

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; }

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Brendan Gregg39100.00%1100.00%
Total39100.00%1100.00%


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 > PAGE_OFFSET) { sym = ksym_search(counts[i].ip); 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"); } }

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Brendan Gregg22399.11%150.00%
Joe Stringer20.89%150.00%
Total225100.00%2100.00%


static void int_exit(int sig) { printf("\n"); print_ip_map(map_fd[0]); exit(0); }

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Brendan Gregg27100.00%1100.00%
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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\n"); 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\n"); 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):\n", errno); if (strcmp(bpf_log_buf, "") == 0) fprintf(stderr, "Try: ulimit -l unlimited\n"); 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.\n", 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; }

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Brendan Gregg29897.70%150.00%
Andy Gospodarek72.30%150.00%
Total305100.00%2100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Brendan Gregg87298.53%125.00%
Andy Gospodarek70.79%125.00%
Joe Stringer60.68%250.00%
Total885100.00%4100.00%
Directory: samples/bpf
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