samples/bpf: add sampleip example

sample instruction pointer and frequency count in a BPF map

Signed-off-by: Brendan Gregg <bgregg@netflix.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 238 insertions, 0 deletions

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index a69cf9045285..12b7304d55dc 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -26,6 +26,7 @@ hostprogs-y += xdp1
 hostprogs-y += xdp2
 hostprogs-y += test_current_task_under_cgroup
 hostprogs-y += trace_event
+hostprogs-y += sampleip
 
 test_verifier-objs := test_verifier.o libbpf.o
 test_maps-objs := test_maps.o libbpf.o
@@ -54,6 +55,7 @@ xdp2-objs := bpf_load.o libbpf.o xdp1_user.o
 test_current_task_under_cgroup-objs := bpf_load.o libbpf.o \
                                        test_current_task_under_cgroup_user.o
 trace_event-objs := bpf_load.o libbpf.o trace_event_user.o
+sampleip-objs := bpf_load.o libbpf.o sampleip_user.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
@@ -82,6 +84,7 @@ always += xdp1_kern.o
 always += xdp2_kern.o
 always += test_current_task_under_cgroup_kern.o
 always += trace_event_kern.o
+always += sampleip_kern.o
 
 HOSTCFLAGS += -I$(objtree)/usr/include
 
@@ -107,6 +110,7 @@ HOSTLOADLIBES_xdp1 += -lelf
 HOSTLOADLIBES_xdp2 += -lelf
 HOSTLOADLIBES_test_current_task_under_cgroup += -lelf
 HOSTLOADLIBES_trace_event += -lelf
+HOSTLOADLIBES_sampleip += -lelf
 
 # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
 #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
diff --git a/samples/bpf/sampleip_kern.c b/samples/bpf/sampleip_kern.c
new file mode 100644
index 000000000000..774a681f374a
--- /dev/null
+++ b/samples/bpf/sampleip_kern.c
@@ -0,0 +1,38 @@
+/* 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 <linux/version.h>
+#include <linux/ptrace.h>
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/bpf_perf_event.h>
+#include "bpf_helpers.h"
+
+#define MAX_IPS         8192
+
+struct bpf_map_def SEC("maps") ip_map = {
+        .type = BPF_MAP_TYPE_HASH,
+        .key_size = sizeof(u64),
+        .value_size = sizeof(u32),
+        .max_entries = MAX_IPS,
+};
+
+SEC("perf_event")
+int do_sample(struct bpf_perf_event_data *ctx)
+{
+        u64 ip;
+        u32 *value, init_val = 1;
+
+        ip = ctx->regs.ip;
+        value = bpf_map_lookup_elem(&ip_map, &ip);
+        if (value)
+                *value += 1;
+        else
+                /* E2BIG not tested for this example only */
+                bpf_map_update_elem(&ip_map, &ip, &init_val, BPF_NOEXIST);
+
+        return 0;
+}
+char _license[] SEC("license") = "GPL";
diff --git a/samples/bpf/sampleip_user.c b/samples/bpf/sampleip_user.c
new file mode 100644
index 000000000000..260a6bdd6413
--- /dev/null
+++ b/samples/bpf/sampleip_user.c
@@ -0,0 +1,196 @@
+/*
+ * 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"
+
+#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");
+}
+
+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] = 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;
+}
+
+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\n", "ADDR", "KSYM", "COUNT");
+
+        /* fetch IPs and counts */
+        key = 0, i = 0;
+        while (bpf_get_next_key(fd, &key, &next_key) == 0) {
+                bpf_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");
+        }
+}
+
+static void int_exit(int sig)
+{
+        printf("\n");
+        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\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);
+
+        /* 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;
+}