builtin-ftrace.c

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/*
 * builtin-ftrace.c
 *
 * Copyright (c) 2013  LG Electronics,  Namhyung Kim <namhyung@kernel.org>
 *
 * Released under the GPL v2.
 */

#include "builtin.h"
#include "perf.h"

#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <poll.h>

#include "debug.h"
#include <subcmd/parse-options.h>
#include <api/fs/tracing_path.h>
#include "evlist.h"
#include "target.h"
#include "cpumap.h"
#include "thread_map.h"
#include "util/config.h"


#define DEFAULT_TRACER  "function_graph"

struct perf_ftrace {
    struct perf_evlist  *evlist;
    struct target       target;
    const char      *tracer;
    struct list_head    filters;
    struct list_head    notrace;
    struct list_head    graph_funcs;
    struct list_head    nograph_funcs;
    int         graph_depth;
};

struct filter_entry {
    struct list_head    list;
    char            name[];
};

static bool done;

static void sig_handler(int sig __maybe_unused)
{
    done = true;
}

/*
 * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
 * we asked by setting its exec_error to the function below,
 * ftrace__workload_exec_failed_signal.
 *
 * XXX We need to handle this more appropriately, emitting an error, etc.
 */
static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
                        siginfo_t *info __maybe_unused,
                        void *ucontext __maybe_unused)
{
    /* workload_exec_errno = info->si_value.sival_int; */
    done = true;
}

static int __write_tracing_file(const char *name, const char *val, bool append)
{
    char *file;
    int fd, ret = -1;
    ssize_t size = strlen(val);
    int flags = O_WRONLY;
    char errbuf[512];
    char *val_copy;

    file = get_tracing_file(name);
    if (!file) {
        pr_debug("cannot get tracing file: %s\n", name);
        return -1;
    }

    if (append)
        flags |= O_APPEND;
    else
        flags |= O_TRUNC;

    fd = open(file, flags);
    if (fd < 0) {
        pr_debug("cannot open tracing file: %s: %s\n",
             name, str_error_r(errno, errbuf, sizeof(errbuf)));
        goto out;
    }

    /*
     * Copy the original value and append a '\n'. Without this,
     * the kernel can hide possible errors.
     */
    val_copy = strdup(val);
    if (!val_copy)
        goto out_close;
    val_copy[size] = '\n';

    if (write(fd, val_copy, size + 1) == size + 1)
        ret = 0;
    else
        pr_debug("write '%s' to tracing/%s failed: %s\n",
             val, name, str_error_r(errno, errbuf, sizeof(errbuf)));

    free(val_copy);
out_close:
    close(fd);
out:
    put_tracing_file(file);
    return ret;
}

static int write_tracing_file(const char *name, const char *val)
{
    return __write_tracing_file(name, val, false);
}

static int append_tracing_file(const char *name, const char *val)
{
    return __write_tracing_file(name, val, true);
}

static int reset_tracing_cpu(void);
static void reset_tracing_filters(void);

static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
{
    if (write_tracing_file("tracing_on", "0") < 0)
        return -1;

    if (write_tracing_file("current_tracer", "nop") < 0)
        return -1;

    if (write_tracing_file("set_ftrace_pid", " ") < 0)
        return -1;

    if (reset_tracing_cpu() < 0)
        return -1;

    if (write_tracing_file("max_graph_depth", "0") < 0)
        return -1;

    reset_tracing_filters();
    return 0;
}

static int set_tracing_pid(struct perf_ftrace *ftrace)
{
    int i;
    char buf[16];

    if (target__has_cpu(&ftrace->target))
        return 0;

    for (i = 0; i < thread_map__nr(ftrace->evlist->threads); i++) {
        scnprintf(buf, sizeof(buf), "%d",
              ftrace->evlist->threads->map[i]);
        if (append_tracing_file("set_ftrace_pid", buf) < 0)
            return -1;
    }
    return 0;
}

static int set_tracing_cpumask(struct cpu_map *cpumap)
{
    char *cpumask;
    size_t mask_size;
    int ret;
    int last_cpu;

    last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
    mask_size = (last_cpu + 3) / 4 + 1;
    mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */

    cpumask = malloc(mask_size);
    if (cpumask == NULL) {
        pr_debug("failed to allocate cpu mask\n");
        return -1;
    }

    cpu_map__snprint_mask(cpumap, cpumask, mask_size);

    ret = write_tracing_file("tracing_cpumask", cpumask);

    free(cpumask);
    return ret;
}

static int set_tracing_cpu(struct perf_ftrace *ftrace)
{
    struct cpu_map *cpumap = ftrace->evlist->cpus;

    if (!target__has_cpu(&ftrace->target))
        return 0;

    return set_tracing_cpumask(cpumap);
}

static int reset_tracing_cpu(void)
{
    struct cpu_map *cpumap = cpu_map__new(NULL);
    int ret;

    ret = set_tracing_cpumask(cpumap);
    cpu_map__put(cpumap);
    return ret;
}

static int __set_tracing_filter(const char *filter_file, struct list_head *funcs)
{
    struct filter_entry *pos;

    list_for_each_entry(pos, funcs, list) {
        if (append_tracing_file(filter_file, pos->name) < 0)
            return -1;
    }

    return 0;
}

static int set_tracing_filters(struct perf_ftrace *ftrace)
{
    int ret;

    ret = __set_tracing_filter("set_ftrace_filter", &ftrace->filters);
    if (ret < 0)
        return ret;

    ret = __set_tracing_filter("set_ftrace_notrace", &ftrace->notrace);
    if (ret < 0)
        return ret;

    ret = __set_tracing_filter("set_graph_function", &ftrace->graph_funcs);
    if (ret < 0)
        return ret;

    /* old kernels do not have this filter */
    __set_tracing_filter("set_graph_notrace", &ftrace->nograph_funcs);

    return ret;
}

static void reset_tracing_filters(void)
{
    write_tracing_file("set_ftrace_filter", " ");
    write_tracing_file("set_ftrace_notrace", " ");
    write_tracing_file("set_graph_function", " ");
    write_tracing_file("set_graph_notrace", " ");
}

static int set_tracing_depth(struct perf_ftrace *ftrace)
{
    char buf[16];

    if (ftrace->graph_depth == 0)
        return 0;

    if (ftrace->graph_depth < 0) {
        pr_err("invalid graph depth: %d\n", ftrace->graph_depth);
        return -1;
    }

    snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);

    if (write_tracing_file("max_graph_depth", buf) < 0)
        return -1;

    return 0;
}

static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
{
    char *trace_file;
    int trace_fd;
    char buf[4096];
    struct pollfd pollfd = {
        .events = POLLIN,
    };

    if (geteuid() != 0) {
        pr_err("ftrace only works for root!\n");
        return -1;
    }

    signal(SIGINT, sig_handler);
    signal(SIGUSR1, sig_handler);
    signal(SIGCHLD, sig_handler);
    signal(SIGPIPE, sig_handler);

    if (reset_tracing_files(ftrace) < 0) {
        pr_err("failed to reset ftrace\n");
        goto out;
    }

    /* reset ftrace buffer */
    if (write_tracing_file("trace", "0") < 0)
        goto out;

    if (argc && perf_evlist__prepare_workload(ftrace->evlist,
                &ftrace->target, argv, false,
                ftrace__workload_exec_failed_signal) < 0) {
        goto out;
    }

    if (set_tracing_pid(ftrace) < 0) {
        pr_err("failed to set ftrace pid\n");
        goto out_reset;
    }

    if (set_tracing_cpu(ftrace) < 0) {
        pr_err("failed to set tracing cpumask\n");
        goto out_reset;
    }

    if (set_tracing_filters(ftrace) < 0) {
        pr_err("failed to set tracing filters\n");
        goto out_reset;
    }

    if (set_tracing_depth(ftrace) < 0) {
        pr_err("failed to set graph depth\n");
        goto out_reset;
    }

    if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
        pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
        goto out_reset;
    }

    setup_pager();

    trace_file = get_tracing_file("trace_pipe");
    if (!trace_file) {
        pr_err("failed to open trace_pipe\n");
        goto out_reset;
    }

    trace_fd = open(trace_file, O_RDONLY);

    put_tracing_file(trace_file);

    if (trace_fd < 0) {
        pr_err("failed to open trace_pipe\n");
        goto out_reset;
    }

    fcntl(trace_fd, F_SETFL, O_NONBLOCK);
    pollfd.fd = trace_fd;

    if (write_tracing_file("tracing_on", "1") < 0) {
        pr_err("can't enable tracing\n");
        goto out_close_fd;
    }

    perf_evlist__start_workload(ftrace->evlist);

    while (!done) {
        if (poll(&pollfd, 1, -1) < 0)
            break;

        if (pollfd.revents & POLLIN) {
            int n = read(trace_fd, buf, sizeof(buf));
            if (n < 0)
                break;
            if (fwrite(buf, n, 1, stdout) != 1)
                break;
        }
    }

    write_tracing_file("tracing_on", "0");

    /* read remaining buffer contents */
    while (true) {
        int n = read(trace_fd, buf, sizeof(buf));
        if (n <= 0)
            break;
        if (fwrite(buf, n, 1, stdout) != 1)
            break;
    }

out_close_fd:
    close(trace_fd);
out_reset:
    reset_tracing_files(ftrace);
out:
    return done ? 0 : -1;
}

static int perf_ftrace_config(const char *var, const char *value, void *cb)
{
    struct perf_ftrace *ftrace = cb;

    if (!strstarts(var, "ftrace."))
        return 0;

    if (strcmp(var, "ftrace.tracer"))
        return -1;

    if (!strcmp(value, "function_graph") ||
        !strcmp(value, "function")) {
        ftrace->tracer = value;
        return 0;
    }

    pr_err("Please select \"function_graph\" (default) or \"function\"\n");
    return -1;
}

static int parse_filter_func(const struct option *opt, const char *str,
                 int unset __maybe_unused)
{
    struct list_head *head = opt->value;
    struct filter_entry *entry;

    entry = malloc(sizeof(*entry) + strlen(str) + 1);
    if (entry == NULL)
        return -ENOMEM;

    strcpy(entry->name, str);
    list_add_tail(&entry->list, head);

    return 0;
}

static void delete_filter_func(struct list_head *head)
{
    struct filter_entry *pos, *tmp;

    list_for_each_entry_safe(pos, tmp, head, list) {
        list_del(&pos->list);
        free(pos);
    }
}

int cmd_ftrace(int argc, const char **argv)
{
    int ret;
    struct perf_ftrace ftrace = {
        .tracer = DEFAULT_TRACER,
        .target = { .uid = UINT_MAX, },
    };
    const char * const ftrace_usage[] = {
        "perf ftrace [<options>] [<command>]",
        "perf ftrace [<options>] -- <command> [<options>]",
        NULL
    };
    const struct option ftrace_options[] = {
    OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
           "tracer to use: function_graph(default) or function"),
    OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
           "trace on existing process id"),
    OPT_INCR('v', "verbose", &verbose,
         "be more verbose"),
    OPT_BOOLEAN('a', "all-cpus", &ftrace.target.system_wide,
            "system-wide collection from all CPUs"),
    OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
            "list of cpus to monitor"),
    OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",
             "trace given functions only", parse_filter_func),
    OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
             "do not trace given functions", parse_filter_func),
    OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
             "Set graph filter on given functions", parse_filter_func),
    OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",
             "Set nograph filter on given functions", parse_filter_func),
    OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
            "Max depth for function graph tracer"),
    OPT_END()
    };

    INIT_LIST_HEAD(&ftrace.filters);
    INIT_LIST_HEAD(&ftrace.notrace);
    INIT_LIST_HEAD(&ftrace.graph_funcs);
    INIT_LIST_HEAD(&ftrace.nograph_funcs);

    ret = perf_config(perf_ftrace_config, &ftrace);
    if (ret < 0)
        return -1;

    argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
                PARSE_OPT_STOP_AT_NON_OPTION);
    if (!argc && target__none(&ftrace.target))
        usage_with_options(ftrace_usage, ftrace_options);

    ret = target__validate(&ftrace.target);
    if (ret) {
        char errbuf[512];

        target__strerror(&ftrace.target, ret, errbuf, 512);
        pr_err("%s\n", errbuf);
        goto out_delete_filters;
    }

    ftrace.evlist = perf_evlist__new();
    if (ftrace.evlist == NULL) {
        ret = -ENOMEM;
        goto out_delete_filters;
    }

    ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
    if (ret < 0)
        goto out_delete_evlist;

    ret = __cmd_ftrace(&ftrace, argc, argv);

out_delete_evlist:
    perf_evlist__delete(ftrace.evlist);

out_delete_filters:
    delete_filter_func(&ftrace.filters);
    delete_filter_func(&ftrace.notrace);
    delete_filter_func(&ftrace.graph_funcs);
    delete_filter_func(&ftrace.nograph_funcs);

    return ret;
}