// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Parts came from builtin-{top,stat,record}.c, see those files for further
 * copyright notes.
 */
#include <api/fs/fs.h>
#include <errno.h>
#include <inttypes.h>
#include <poll.h>
#include "cpumap.h"
#include "util/mmap.h"
#include "thread_map.h"
#include "target.h"
#include "evlist.h"
#include "evsel.h"
#include "debug.h"
#include "units.h"
#include <internal/lib.h> // page_size
#include "affinity.h"
#include "../perf.h"
#include "asm/bug.h"
#include "bpf-event.h"
#include "util/string2.h"
#include "util/perf_api_probe.h"
#include <signal.h>
#include <unistd.h>
#include <sched.h>
#include <stdlib.h>

#include "parse-events.h"
#include <subcmd/parse-options.h>

#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>

#include <linux/bitops.h>
#include <linux/hash.h>
#include <linux/log2.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/zalloc.h>
#include <perf/evlist.h>
#include <perf/evsel.h>
#include <perf/cpumap.h>
#include <perf/mmap.h>

#include <internal/xyarray.h>

#ifdef LACKS_SIGQUEUE_PROTOTYPE
int sigqueue(pid_t pid, int sig, const union sigval value);
#endif

#define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y))
#define SID(e, x, y) xyarray__entry(e->core.sample_id, x, y)

void evlist__init(struct evlist *evlist, struct perf_cpu_map *cpus,
                  struct perf_thread_map *threads)
{
        perf_evlist__init(&evlist->core);
        perf_evlist__set_maps(&evlist->core, cpus, threads);
        evlist->workload.pid = -1;
        evlist->bkw_mmap_state = BKW_MMAP_NOTREADY;
        evlist->ctl_fd.fd = -1;
        evlist->ctl_fd.ack = -1;
        evlist->ctl_fd.pos = -1;
}

struct evlist *evlist__new(void)
{
        struct evlist *evlist = zalloc(sizeof(*evlist));

        if (evlist != NULL)
                evlist__init(evlist, NULL, NULL);

        return evlist;
}

struct evlist *perf_evlist__new_default(void)
{
        struct evlist *evlist = evlist__new();

        if (evlist && evlist__add_default(evlist)) {
                evlist__delete(evlist);
                evlist = NULL;
        }

        return evlist;
}

struct evlist *perf_evlist__new_dummy(void)
{
        struct evlist *evlist = evlist__new();

        if (evlist && evlist__add_dummy(evlist)) {
                evlist__delete(evlist);
                evlist = NULL;
        }

        return evlist;
}

/**
 * perf_evlist__set_id_pos - set the positions of event ids.
 * @evlist: selected event list
 *
 * Events with compatible sample types all have the same id_pos
 * and is_pos.  For convenience, put a copy on evlist.
 */
void perf_evlist__set_id_pos(struct evlist *evlist)
{
        struct evsel *first = evlist__first(evlist);

        evlist->id_pos = first->id_pos;
        evlist->is_pos = first->is_pos;
}

static void perf_evlist__update_id_pos(struct evlist *evlist)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel)
                evsel__calc_id_pos(evsel);

        perf_evlist__set_id_pos(evlist);
}

static void evlist__purge(struct evlist *evlist)
{
        struct evsel *pos, *n;

        evlist__for_each_entry_safe(evlist, n, pos) {
                list_del_init(&pos->core.node);
                pos->evlist = NULL;
                evsel__delete(pos);
        }

        evlist->core.nr_entries = 0;
}

void evlist__exit(struct evlist *evlist)
{
        zfree(&evlist->mmap);
        zfree(&evlist->overwrite_mmap);
        perf_evlist__exit(&evlist->core);
}

void evlist__delete(struct evlist *evlist)
{
        if (evlist == NULL)
                return;

        evlist__munmap(evlist);
        evlist__close(evlist);
        evlist__purge(evlist);
        evlist__exit(evlist);
        free(evlist);
}

void evlist__add(struct evlist *evlist, struct evsel *entry)
{
        entry->evlist = evlist;
        entry->idx = evlist->core.nr_entries;
        entry->tracking = !entry->idx;

        perf_evlist__add(&evlist->core, &entry->core);

        if (evlist->core.nr_entries == 1)
                perf_evlist__set_id_pos(evlist);
}

void evlist__remove(struct evlist *evlist, struct evsel *evsel)
{
        evsel->evlist = NULL;
        perf_evlist__remove(&evlist->core, &evsel->core);
}

void perf_evlist__splice_list_tail(struct evlist *evlist,
                                   struct list_head *list)
{
        struct evsel *evsel, *temp;

        __evlist__for_each_entry_safe(list, temp, evsel) {
                list_del_init(&evsel->core.node);
                evlist__add(evlist, evsel);
        }
}

int __evlist__set_tracepoints_handlers(struct evlist *evlist,
                                       const struct evsel_str_handler *assocs, size_t nr_assocs)
{
        struct evsel *evsel;
        size_t i;
        int err;

        for (i = 0; i < nr_assocs; i++) {
                // Adding a handler for an event not in this evlist, just ignore it.
                evsel = perf_evlist__find_tracepoint_by_name(evlist, assocs[i].name);
                if (evsel == NULL)
                        continue;

                err = -EEXIST;
                if (evsel->handler != NULL)
                        goto out;
                evsel->handler = assocs[i].handler;
        }

        err = 0;
out:
        return err;
}

void __perf_evlist__set_leader(struct list_head *list)
{
        struct evsel *evsel, *leader;

        leader = list_entry(list->next, struct evsel, core.node);
        evsel = list_entry(list->prev, struct evsel, core.node);

        leader->core.nr_members = evsel->idx - leader->idx + 1;

        __evlist__for_each_entry(list, evsel) {
                evsel->leader = leader;
        }
}

void perf_evlist__set_leader(struct evlist *evlist)
{
        if (evlist->core.nr_entries) {
                evlist->nr_groups = evlist->core.nr_entries > 1 ? 1 : 0;
                __perf_evlist__set_leader(&evlist->core.entries);
        }
}

int __evlist__add_default(struct evlist *evlist, bool precise)
{
        struct evsel *evsel = evsel__new_cycles(precise);

        if (evsel == NULL)
                return -ENOMEM;

        evlist__add(evlist, evsel);
        return 0;
}

int evlist__add_dummy(struct evlist *evlist)
{
        struct perf_event_attr attr = {
                .type   = PERF_TYPE_SOFTWARE,
                .config = PERF_COUNT_SW_DUMMY,
                .size   = sizeof(attr), /* to capture ABI version */
        };
        struct evsel *evsel = evsel__new_idx(&attr, evlist->core.nr_entries);

        if (evsel == NULL)
                return -ENOMEM;

        evlist__add(evlist, evsel);
        return 0;
}

static int evlist__add_attrs(struct evlist *evlist, struct perf_event_attr *attrs, size_t nr_attrs)
{
        struct evsel *evsel, *n;
        LIST_HEAD(head);
        size_t i;

        for (i = 0; i < nr_attrs; i++) {
                evsel = evsel__new_idx(attrs + i, evlist->core.nr_entries + i);
                if (evsel == NULL)
                        goto out_delete_partial_list;
                list_add_tail(&evsel->core.node, &head);
        }

        perf_evlist__splice_list_tail(evlist, &head);

        return 0;

out_delete_partial_list:
        __evlist__for_each_entry_safe(&head, n, evsel)
                evsel__delete(evsel);
        return -1;
}

int __evlist__add_default_attrs(struct evlist *evlist, struct perf_event_attr *attrs, size_t nr_attrs)
{
        size_t i;

        for (i = 0; i < nr_attrs; i++)
                event_attr_init(attrs + i);

        return evlist__add_attrs(evlist, attrs, nr_attrs);
}

struct evsel *
perf_evlist__find_tracepoint_by_id(struct evlist *evlist, int id)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->core.attr.type   == PERF_TYPE_TRACEPOINT &&
                    (int)evsel->core.attr.config == id)
                        return evsel;
        }

        return NULL;
}

struct evsel *
perf_evlist__find_tracepoint_by_name(struct evlist *evlist,
                                     const char *name)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if ((evsel->core.attr.type == PERF_TYPE_TRACEPOINT) &&
                    (strcmp(evsel->name, name) == 0))
                        return evsel;
        }

        return NULL;
}

int evlist__add_newtp(struct evlist *evlist, const char *sys, const char *name, void *handler)
{
        struct evsel *evsel = evsel__newtp(sys, name);

        if (IS_ERR(evsel))
                return -1;

        evsel->handler = handler;
        evlist__add(evlist, evsel);
        return 0;
}

static int perf_evlist__nr_threads(struct evlist *evlist,
                                   struct evsel *evsel)
{
        if (evsel->core.system_wide)
                return 1;
        else
                return perf_thread_map__nr(evlist->core.threads);
}

void evlist__cpu_iter_start(struct evlist *evlist)
{
        struct evsel *pos;

        /*
         * Reset the per evsel cpu_iter. This is needed because
         * each evsel's cpumap may have a different index space,
         * and some operations need the index to modify
         * the FD xyarray (e.g. open, close)
         */
        evlist__for_each_entry(evlist, pos)
                pos->cpu_iter = 0;
}

bool evsel__cpu_iter_skip_no_inc(struct evsel *ev, int cpu)
{
        if (ev->cpu_iter >= ev->core.cpus->nr)
                return true;
        if (cpu >= 0 && ev->core.cpus->map[ev->cpu_iter] != cpu)
                return true;
        return false;
}

bool evsel__cpu_iter_skip(struct evsel *ev, int cpu)
{
        if (!evsel__cpu_iter_skip_no_inc(ev, cpu)) {
                ev->cpu_iter++;
                return false;
        }
        return true;
}

void evlist__disable(struct evlist *evlist)
{
        struct evsel *pos;
        struct affinity affinity;
        int cpu, i, imm = 0;
        bool has_imm = false;

        if (affinity__setup(&affinity) < 0)
                return;

        /* Disable 'immediate' events last */
        for (imm = 0; imm <= 1; imm++) {
                evlist__for_each_cpu(evlist, i, cpu) {
                        affinity__set(&affinity, cpu);

                        evlist__for_each_entry(evlist, pos) {
                                if (evsel__cpu_iter_skip(pos, cpu))
                                        continue;
                                if (pos->disabled || !evsel__is_group_leader(pos) || !pos->core.fd)
                                        continue;
                                if (pos->immediate)
                                        has_imm = true;
                                if (pos->immediate != imm)
                                        continue;
                                evsel__disable_cpu(pos, pos->cpu_iter - 1);
                        }
                }
                if (!has_imm)
                        break;
        }

        affinity__cleanup(&affinity);
        evlist__for_each_entry(evlist, pos) {
                if (!evsel__is_group_leader(pos) || !pos->core.fd)
                        continue;
                pos->disabled = true;
        }

        evlist->enabled = false;
}

void evlist__enable(struct evlist *evlist)
{
        struct evsel *pos;
        struct affinity affinity;
        int cpu, i;

        if (affinity__setup(&affinity) < 0)
                return;

        evlist__for_each_cpu(evlist, i, cpu) {
                affinity__set(&affinity, cpu);

                evlist__for_each_entry(evlist, pos) {
                        if (evsel__cpu_iter_skip(pos, cpu))
                                continue;
                        if (!evsel__is_group_leader(pos) || !pos->core.fd)
                                continue;
                        evsel__enable_cpu(pos, pos->cpu_iter - 1);
                }
        }
        affinity__cleanup(&affinity);
        evlist__for_each_entry(evlist, pos) {
                if (!evsel__is_group_leader(pos) || !pos->core.fd)
                        continue;
                pos->disabled = false;
        }

        evlist->enabled = true;
}

void perf_evlist__toggle_enable(struct evlist *evlist)
{
        (evlist->enabled ? evlist__disable : evlist__enable)(evlist);
}

static int perf_evlist__enable_event_cpu(struct evlist *evlist,
                                         struct evsel *evsel, int cpu)
{
        int thread;
        int nr_threads = perf_evlist__nr_threads(evlist, evsel);

        if (!evsel->core.fd)
                return -EINVAL;

        for (thread = 0; thread < nr_threads; thread++) {
                int err = ioctl(FD(evsel, cpu, thread), PERF_EVENT_IOC_ENABLE, 0);
                if (err)
                        return err;
        }
        return 0;
}

static int perf_evlist__enable_event_thread(struct evlist *evlist,
                                            struct evsel *evsel,
                                            int thread)
{
        int cpu;
        int nr_cpus = perf_cpu_map__nr(evlist->core.cpus);

        if (!evsel->core.fd)
                return -EINVAL;

        for (cpu = 0; cpu < nr_cpus; cpu++) {
                int err = ioctl(FD(evsel, cpu, thread), PERF_EVENT_IOC_ENABLE, 0);
                if (err)
                        return err;
        }
        return 0;
}

int perf_evlist__enable_event_idx(struct evlist *evlist,
                                  struct evsel *evsel, int idx)
{
        bool per_cpu_mmaps = !perf_cpu_map__empty(evlist->core.cpus);

        if (per_cpu_mmaps)
                return perf_evlist__enable_event_cpu(evlist, evsel, idx);
        else
                return perf_evlist__enable_event_thread(evlist, evsel, idx);
}

int evlist__add_pollfd(struct evlist *evlist, int fd)
{
        return perf_evlist__add_pollfd(&evlist->core, fd, NULL, POLLIN, fdarray_flag__default);
}

int evlist__filter_pollfd(struct evlist *evlist, short revents_and_mask)
{
        return perf_evlist__filter_pollfd(&evlist->core, revents_and_mask);
}

int evlist__poll(struct evlist *evlist, int timeout)
{
        return perf_evlist__poll(&evlist->core, timeout);
}

struct perf_sample_id *perf_evlist__id2sid(struct evlist *evlist, u64 id)
{
        struct hlist_head *head;
        struct perf_sample_id *sid;
        int hash;

        hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
        head = &evlist->core.heads[hash];

        hlist_for_each_entry(sid, head, node)
                if (sid->id == id)
                        return sid;

        return NULL;
}

struct evsel *perf_evlist__id2evsel(struct evlist *evlist, u64 id)
{
        struct perf_sample_id *sid;

        if (evlist->core.nr_entries == 1 || !id)
                return evlist__first(evlist);

        sid = perf_evlist__id2sid(evlist, id);
        if (sid)
                return container_of(sid->evsel, struct evsel, core);

        if (!evlist__sample_id_all(evlist))
                return evlist__first(evlist);

        return NULL;
}

struct evsel *perf_evlist__id2evsel_strict(struct evlist *evlist,
                                                u64 id)
{
        struct perf_sample_id *sid;

        if (!id)
                return NULL;

        sid = perf_evlist__id2sid(evlist, id);
        if (sid)
                return container_of(sid->evsel, struct evsel, core);

        return NULL;
}

static int perf_evlist__event2id(struct evlist *evlist,
                                 union perf_event *event, u64 *id)
{
        const __u64 *array = event->sample.array;
        ssize_t n;

        n = (event->header.size - sizeof(event->header)) >> 3;

        if (event->header.type == PERF_RECORD_SAMPLE) {
                if (evlist->id_pos >= n)
                        return -1;
                *id = array[evlist->id_pos];
        } else {
                if (evlist->is_pos > n)
                        return -1;
                n -= evlist->is_pos;
                *id = array[n];
        }
        return 0;
}

struct evsel *perf_evlist__event2evsel(struct evlist *evlist,
                                            union perf_event *event)
{
        struct evsel *first = evlist__first(evlist);
        struct hlist_head *head;
        struct perf_sample_id *sid;
        int hash;
        u64 id;

        if (evlist->core.nr_entries == 1)
                return first;

        if (!first->core.attr.sample_id_all &&
            event->header.type != PERF_RECORD_SAMPLE)
                return first;

        if (perf_evlist__event2id(evlist, event, &id))
                return NULL;

        /* Synthesized events have an id of zero */
        if (!id)
                return first;

        hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
        head = &evlist->core.heads[hash];

        hlist_for_each_entry(sid, head, node) {
                if (sid->id == id)
                        return container_of(sid->evsel, struct evsel, core);
        }
        return NULL;
}

static int perf_evlist__set_paused(struct evlist *evlist, bool value)
{
        int i;

        if (!evlist->overwrite_mmap)
                return 0;

        for (i = 0; i < evlist->core.nr_mmaps; i++) {
                int fd = evlist->overwrite_mmap[i].core.fd;
                int err;

                if (fd < 0)
                        continue;
                err = ioctl(fd, PERF_EVENT_IOC_PAUSE_OUTPUT, value ? 1 : 0);
                if (err)
                        return err;
        }
        return 0;
}

static int perf_evlist__pause(struct evlist *evlist)
{
        return perf_evlist__set_paused(evlist, true);
}

static int perf_evlist__resume(struct evlist *evlist)
{
        return perf_evlist__set_paused(evlist, false);
}

static void evlist__munmap_nofree(struct evlist *evlist)
{
        int i;

        if (evlist->mmap)
                for (i = 0; i < evlist->core.nr_mmaps; i++)
                        perf_mmap__munmap(&evlist->mmap[i].core);

        if (evlist->overwrite_mmap)
                for (i = 0; i < evlist->core.nr_mmaps; i++)
                        perf_mmap__munmap(&evlist->overwrite_mmap[i].core);
}

void evlist__munmap(struct evlist *evlist)
{
        evlist__munmap_nofree(evlist);
        zfree(&evlist->mmap);
        zfree(&evlist->overwrite_mmap);
}

static void perf_mmap__unmap_cb(struct perf_mmap *map)
{
        struct mmap *m = container_of(map, struct mmap, core);

        mmap__munmap(m);
}

static struct mmap *evlist__alloc_mmap(struct evlist *evlist,
                                       bool overwrite)
{
        int i;
        struct mmap *map;

        map = zalloc(evlist->core.nr_mmaps * sizeof(struct mmap));
        if (!map)
                return NULL;

        for (i = 0; i < evlist->core.nr_mmaps; i++) {
                struct perf_mmap *prev = i ? &map[i - 1].core : NULL;

                /*
                 * When the perf_mmap() call is made we grab one refcount, plus
                 * one extra to let perf_mmap__consume() get the last
                 * events after all real references (perf_mmap__get()) are
                 * dropped.
                 *
                 * Each PERF_EVENT_IOC_SET_OUTPUT points to this mmap and
                 * thus does perf_mmap__get() on it.
                 */
                perf_mmap__init(&map[i].core, prev, overwrite, perf_mmap__unmap_cb);
        }

        return map;
}

static void
perf_evlist__mmap_cb_idx(struct perf_evlist *_evlist,
                         struct perf_mmap_param *_mp,
                         int idx, bool per_cpu)
{
        struct evlist *evlist = container_of(_evlist, struct evlist, core);
        struct mmap_params *mp = container_of(_mp, struct mmap_params, core);

        auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, idx, per_cpu);
}

static struct perf_mmap*
perf_evlist__mmap_cb_get(struct perf_evlist *_evlist, bool overwrite, int idx)
{
        struct evlist *evlist = container_of(_evlist, struct evlist, core);
        struct mmap *maps;

        maps = overwrite ? evlist->overwrite_mmap : evlist->mmap;

        if (!maps) {
                maps = evlist__alloc_mmap(evlist, overwrite);
                if (!maps)
                        return NULL;

                if (overwrite) {
                        evlist->overwrite_mmap = maps;
                        if (evlist->bkw_mmap_state == BKW_MMAP_NOTREADY)
                                perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING);
                } else {
                        evlist->mmap = maps;
                }
        }

        return &maps[idx].core;
}

static int
perf_evlist__mmap_cb_mmap(struct perf_mmap *_map, struct perf_mmap_param *_mp,
                          int output, int cpu)
{
        struct mmap *map = container_of(_map, struct mmap, core);
        struct mmap_params *mp = container_of(_mp, struct mmap_params, core);

        return mmap__mmap(map, mp, output, cpu);
}

unsigned long perf_event_mlock_kb_in_pages(void)
{
        unsigned long pages;
        int max;

        if (sysctl__read_int("kernel/perf_event_mlock_kb", &max) < 0) {
                /*
                 * Pick a once upon a time good value, i.e. things look
                 * strange since we can't read a sysctl value, but lets not
                 * die yet...
                 */
                max = 512;
        } else {
                max -= (page_size / 1024);
        }

        pages = (max * 1024) / page_size;
        if (!is_power_of_2(pages))
                pages = rounddown_pow_of_two(pages);

        return pages;
}

size_t evlist__mmap_size(unsigned long pages)
{
        if (pages == UINT_MAX)
                pages = perf_event_mlock_kb_in_pages();
        else if (!is_power_of_2(pages))
                return 0;

        return (pages + 1) * page_size;
}

static long parse_pages_arg(const char *str, unsigned long min,
                            unsigned long max)
{
        unsigned long pages, val;
        static struct parse_tag tags[] = {
                { .tag  = 'B', .mult = 1       },
                { .tag  = 'K', .mult = 1 << 10 },
                { .tag  = 'M', .mult = 1 << 20 },
                { .tag  = 'G', .mult = 1 << 30 },
                { .tag  = 0 },
        };

        if (str == NULL)
                return -EINVAL;

        val = parse_tag_value(str, tags);
        if (val != (unsigned long) -1) {
                /* we got file size value */
                pages = PERF_ALIGN(val, page_size) / page_size;
        } else {
                /* we got pages count value */
                char *eptr;
                pages = strtoul(str, &eptr, 10);
                if (*eptr != '\0')
                        return -EINVAL;
        }

        if (pages == 0 && min == 0) {
                /* leave number of pages at 0 */
        } else if (!is_power_of_2(pages)) {
                char buf[100];

                /* round pages up to next power of 2 */
                pages = roundup_pow_of_two(pages);
                if (!pages)
                        return -EINVAL;

                unit_number__scnprintf(buf, sizeof(buf), pages * page_size);
                pr_info("rounding mmap pages size to %s (%lu pages)\n",
                        buf, pages);
        }

        if (pages > max)
                return -EINVAL;

        return pages;
}

int __perf_evlist__parse_mmap_pages(unsigned int *mmap_pages, const char *str)
{
        unsigned long max = UINT_MAX;
        long pages;

        if (max > SIZE_MAX / page_size)
                max = SIZE_MAX / page_size;

        pages = parse_pages_arg(str, 1, max);
        if (pages < 0) {
                pr_err("Invalid argument for --mmap_pages/-m\n");
                return -1;
        }

        *mmap_pages = pages;
        return 0;
}

int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
                                  int unset __maybe_unused)
{
        return __perf_evlist__parse_mmap_pages(opt->value, str);
}

/**
 * evlist__mmap_ex - Create mmaps to receive events.
 * @evlist: list of events
 * @pages: map length in pages
 * @overwrite: overwrite older events?
 * @auxtrace_pages - auxtrace map length in pages
 * @auxtrace_overwrite - overwrite older auxtrace data?
 *
 * If @overwrite is %false the user needs to signal event consumption using
 * perf_mmap__write_tail().  Using evlist__mmap_read() does this
 * automatically.
 *
 * Similarly, if @auxtrace_overwrite is %false the user needs to signal data
 * consumption using auxtrace_mmap__write_tail().
 *
 * Return: %0 on success, negative error code otherwise.
 */
int evlist__mmap_ex(struct evlist *evlist, unsigned int pages,
                         unsigned int auxtrace_pages,
                         bool auxtrace_overwrite, int nr_cblocks, int affinity, int flush,
                         int comp_level)
{
        /*
         * Delay setting mp.prot: set it before calling perf_mmap__mmap.
         * Its value is decided by evsel's write_backward.
         * So &mp should not be passed through const pointer.
         */
        struct mmap_params mp = {
                .nr_cblocks     = nr_cblocks,
                .affinity       = affinity,
                .flush          = flush,
                .comp_level     = comp_level
        };
        struct perf_evlist_mmap_ops ops = {
                .idx  = perf_evlist__mmap_cb_idx,
                .get  = perf_evlist__mmap_cb_get,
                .mmap = perf_evlist__mmap_cb_mmap,
        };

        evlist->core.mmap_len = evlist__mmap_size(pages);
        pr_debug("mmap size %zuB\n", evlist->core.mmap_len);

        auxtrace_mmap_params__init(&mp.auxtrace_mp, evlist->core.mmap_len,
                                   auxtrace_pages, auxtrace_overwrite);

        return perf_evlist__mmap_ops(&evlist->core, &ops, &mp.core);
}

int evlist__mmap(struct evlist *evlist, unsigned int pages)
{
        return evlist__mmap_ex(evlist, pages, 0, false, 0, PERF_AFFINITY_SYS, 1, 0);
}

int perf_evlist__create_maps(struct evlist *evlist, struct target *target)
{
        bool all_threads = (target->per_thread && target->system_wide);
        struct perf_cpu_map *cpus;
        struct perf_thread_map *threads;

        /*
         * If specify '-a' and '--per-thread' to perf record, perf record
         * will override '--per-thread'. target->per_thread = false and
         * target->system_wide = true.
         *
         * If specify '--per-thread' only to perf record,
         * target->per_thread = true and target->system_wide = false.
         *
         * So target->per_thread && target->system_wide is false.
         * For perf record, thread_map__new_str doesn't call
         * thread_map__new_all_cpus. That will keep perf record's
         * current behavior.
         *
         * For perf stat, it allows the case that target->per_thread and
         * target->system_wide are all true. It means to collect system-wide
         * per-thread data. thread_map__new_str will call
         * thread_map__new_all_cpus to enumerate all threads.
         */
        threads = thread_map__new_str(target->pid, target->tid, target->uid,
                                      all_threads);

        if (!threads)
                return -1;

        if (target__uses_dummy_map(target))
                cpus = perf_cpu_map__dummy_new();
        else
                cpus = perf_cpu_map__new(target->cpu_list);

        if (!cpus)
                goto out_delete_threads;

        evlist->core.has_user_cpus = !!target->cpu_list;

        perf_evlist__set_maps(&evlist->core, cpus, threads);

        /* as evlist now has references, put count here */
        perf_cpu_map__put(cpus);
        perf_thread_map__put(threads);

        return 0;

out_delete_threads:
        perf_thread_map__put(threads);
        return -1;
}

void __perf_evlist__set_sample_bit(struct evlist *evlist,
                                   enum perf_event_sample_format bit)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel)
                __evsel__set_sample_bit(evsel, bit);
}

void __perf_evlist__reset_sample_bit(struct evlist *evlist,
                                     enum perf_event_sample_format bit)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel)
                __evsel__reset_sample_bit(evsel, bit);
}

int perf_evlist__apply_filters(struct evlist *evlist, struct evsel **err_evsel)
{
        struct evsel *evsel;
        int err = 0;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->filter == NULL)
                        continue;

                /*
                 * filters only work for tracepoint event, which doesn't have cpu limit.
                 * So evlist and evsel should always be same.
                 */
                err = perf_evsel__apply_filter(&evsel->core, evsel->filter);
                if (err) {
                        *err_evsel = evsel;
                        break;
                }
        }

        return err;
}

int perf_evlist__set_tp_filter(struct evlist *evlist, const char *filter)
{
        struct evsel *evsel;
        int err = 0;

        if (filter == NULL)
                return -1;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->core.attr.type != PERF_TYPE_TRACEPOINT)
                        continue;

                err = evsel__set_filter(evsel, filter);
                if (err)
                        break;
        }

        return err;
}

int perf_evlist__append_tp_filter(struct evlist *evlist, const char *filter)
{
        struct evsel *evsel;
        int err = 0;

        if (filter == NULL)
                return -1;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->core.attr.type != PERF_TYPE_TRACEPOINT)
                        continue;

                err = evsel__append_tp_filter(evsel, filter);
                if (err)
                        break;
        }

        return err;
}

char *asprintf__tp_filter_pids(size_t npids, pid_t *pids)
{
        char *filter;
        size_t i;

        for (i = 0; i < npids; ++i) {
                if (i == 0) {
                        if (asprintf(&filter, "common_pid != %d", pids[i]) < 0)
                                return NULL;
                } else {
                        char *tmp;

                        if (asprintf(&tmp, "%s && common_pid != %d", filter, pids[i]) < 0)
                                goto out_free;

                        free(filter);
                        filter = tmp;
                }
        }

        return filter;
out_free:
        free(filter);
        return NULL;
}

int perf_evlist__set_tp_filter_pids(struct evlist *evlist, size_t npids, pid_t *pids)
{
        char *filter = asprintf__tp_filter_pids(npids, pids);
        int ret = perf_evlist__set_tp_filter(evlist, filter);

        free(filter);
        return ret;
}

int perf_evlist__set_tp_filter_pid(struct evlist *evlist, pid_t pid)
{
        return perf_evlist__set_tp_filter_pids(evlist, 1, &pid);
}

int perf_evlist__append_tp_filter_pids(struct evlist *evlist, size_t npids, pid_t *pids)
{
        char *filter = asprintf__tp_filter_pids(npids, pids);
        int ret = perf_evlist__append_tp_filter(evlist, filter);

        free(filter);
        return ret;
}

int perf_evlist__append_tp_filter_pid(struct evlist *evlist, pid_t pid)
{
        return perf_evlist__append_tp_filter_pids(evlist, 1, &pid);
}

bool evlist__valid_sample_type(struct evlist *evlist)
{
        struct evsel *pos;

        if (evlist->core.nr_entries == 1)
                return true;

        if (evlist->id_pos < 0 || evlist->is_pos < 0)
                return false;

        evlist__for_each_entry(evlist, pos) {
                if (pos->id_pos != evlist->id_pos ||
                    pos->is_pos != evlist->is_pos)
                        return false;
        }

        return true;
}

u64 __evlist__combined_sample_type(struct evlist *evlist)
{
        struct evsel *evsel;

        if (evlist->combined_sample_type)
                return evlist->combined_sample_type;

        evlist__for_each_entry(evlist, evsel)
                evlist->combined_sample_type |= evsel->core.attr.sample_type;

        return evlist->combined_sample_type;
}

u64 evlist__combined_sample_type(struct evlist *evlist)
{
        evlist->combined_sample_type = 0;
        return __evlist__combined_sample_type(evlist);
}

u64 evlist__combined_branch_type(struct evlist *evlist)
{
        struct evsel *evsel;
        u64 branch_type = 0;

        evlist__for_each_entry(evlist, evsel)
                branch_type |= evsel->core.attr.branch_sample_type;
        return branch_type;
}

bool perf_evlist__valid_read_format(struct evlist *evlist)
{
        struct evsel *first = evlist__first(evlist), *pos = first;
        u64 read_format = first->core.attr.read_format;
        u64 sample_type = first->core.attr.sample_type;

        evlist__for_each_entry(evlist, pos) {
                if (read_format != pos->core.attr.read_format) {
                        pr_debug("Read format differs %#" PRIx64 " vs %#" PRIx64 "\n",
                                 read_format, (u64)pos->core.attr.read_format);
                }
        }

        /* PERF_SAMPLE_READ imples PERF_FORMAT_ID. */
        if ((sample_type & PERF_SAMPLE_READ) &&
            !(read_format & PERF_FORMAT_ID)) {
                return false;
        }

        return true;
}

u16 perf_evlist__id_hdr_size(struct evlist *evlist)
{
        struct evsel *first = evlist__first(evlist);
        struct perf_sample *data;
        u64 sample_type;
        u16 size = 0;

        if (!first->core.attr.sample_id_all)
                goto out;

        sample_type = first->core.attr.sample_type;

        if (sample_type & PERF_SAMPLE_TID)
                size += sizeof(data->tid) * 2;

       if (sample_type & PERF_SAMPLE_TIME)
                size += sizeof(data->time);

        if (sample_type & PERF_SAMPLE_ID)
                size += sizeof(data->id);

        if (sample_type & PERF_SAMPLE_STREAM_ID)
                size += sizeof(data->stream_id);

        if (sample_type & PERF_SAMPLE_CPU)
                size += sizeof(data->cpu) * 2;

        if (sample_type & PERF_SAMPLE_IDENTIFIER)
                size += sizeof(data->id);
out:
        return size;
}

bool evlist__valid_sample_id_all(struct evlist *evlist)
{
        struct evsel *first = evlist__first(evlist), *pos = first;

        evlist__for_each_entry_continue(evlist, pos) {
                if (first->core.attr.sample_id_all != pos->core.attr.sample_id_all)
                        return false;
        }

        return true;
}

bool evlist__sample_id_all(struct evlist *evlist)
{
        struct evsel *first = evlist__first(evlist);
        return first->core.attr.sample_id_all;
}

void perf_evlist__set_selected(struct evlist *evlist,
                               struct evsel *evsel)
{
        evlist->selected = evsel;
}

void evlist__close(struct evlist *evlist)
{
        struct evsel *evsel;
        struct affinity affinity;
        int cpu, i;

        /*
         * With perf record core.cpus is usually NULL.
         * Use the old method to handle this for now.
         */
        if (!evlist->core.cpus) {
                evlist__for_each_entry_reverse(evlist, evsel)
                        evsel__close(evsel);
                return;
        }

        if (affinity__setup(&affinity) < 0)
                return;
        evlist__for_each_cpu(evlist, i, cpu) {
                affinity__set(&affinity, cpu);

                evlist__for_each_entry_reverse(evlist, evsel) {
                        if (evsel__cpu_iter_skip(evsel, cpu))
                            continue;
                        perf_evsel__close_cpu(&evsel->core, evsel->cpu_iter - 1);
                }
        }
        affinity__cleanup(&affinity);
        evlist__for_each_entry_reverse(evlist, evsel) {
                perf_evsel__free_fd(&evsel->core);
                perf_evsel__free_id(&evsel->core);
        }
}

static int perf_evlist__create_syswide_maps(struct evlist *evlist)
{
        struct perf_cpu_map *cpus;
        struct perf_thread_map *threads;
        int err = -ENOMEM;

        /*
         * Try reading /sys/devices/system/cpu/online to get
         * an all cpus map.
         *
         * FIXME: -ENOMEM is the best we can do here, the cpu_map
         * code needs an overhaul to properly forward the
         * error, and we may not want to do that fallback to a
         * default cpu identity map :-\
         */
        cpus = perf_cpu_map__new(NULL);
        if (!cpus)
                goto out;

        threads = perf_thread_map__new_dummy();
        if (!threads)
                goto out_put;

        perf_evlist__set_maps(&evlist->core, cpus, threads);

        perf_thread_map__put(threads);
out_put:
        perf_cpu_map__put(cpus);
out:
        return err;
}

int evlist__open(struct evlist *evlist)
{
        struct evsel *evsel;
        int err;

        /*
         * Default: one fd per CPU, all threads, aka systemwide
         * as sys_perf_event_open(cpu = -1, thread = -1) is EINVAL
         */
        if (evlist->core.threads == NULL && evlist->core.cpus == NULL) {
                err = perf_evlist__create_syswide_maps(evlist);
                if (err < 0)
                        goto out_err;
        }

        perf_evlist__update_id_pos(evlist);

        evlist__for_each_entry(evlist, evsel) {
                err = evsel__open(evsel, evsel->core.cpus, evsel->core.threads);
                if (err < 0)
                        goto out_err;
        }

        return 0;
out_err:
        evlist__close(evlist);
        errno = -err;
        return err;
}

int perf_evlist__prepare_workload(struct evlist *evlist, struct target *target,
                                  const char *argv[], bool pipe_output,
                                  void (*exec_error)(int signo, siginfo_t *info, void *ucontext))
{
        int child_ready_pipe[2], go_pipe[2];
        char bf;

        if (pipe(child_ready_pipe) < 0) {
                perror("failed to create 'ready' pipe");
                return -1;
        }

        if (pipe(go_pipe) < 0) {
                perror("failed to create 'go' pipe");
                goto out_close_ready_pipe;
        }

        evlist->workload.pid = fork();
        if (evlist->workload.pid < 0) {
                perror("failed to fork");
                goto out_close_pipes;
        }

        if (!evlist->workload.pid) {
                int ret;

                if (pipe_output)
                        dup2(2, 1);

                signal(SIGTERM, SIG_DFL);

                close(child_ready_pipe[0]);
                close(go_pipe[1]);
                fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);

                /*
                 * Tell the parent we're ready to go
                 */
                close(child_ready_pipe[1]);

                /*
                 * Wait until the parent tells us to go.
                 */
                ret = read(go_pipe[0], &bf, 1);
                /*
                 * The parent will ask for the execvp() to be performed by
                 * writing exactly one byte, in workload.cork_fd, usually via
                 * perf_evlist__start_workload().
                 *
                 * For cancelling the workload without actually running it,
                 * the parent will just close workload.cork_fd, without writing
                 * anything, i.e. read will return zero and we just exit()
                 * here.
                 */
                if (ret != 1) {
                        if (ret == -1)
                                perror("unable to read pipe");
                        exit(ret);
                }

                execvp(argv[0], (char **)argv);

                if (exec_error) {
                        union sigval val;

                        val.sival_int = errno;
                        if (sigqueue(getppid(), SIGUSR1, val))
                                perror(argv[0]);
                } else
                        perror(argv[0]);
                exit(-1);
        }

        if (exec_error) {
                struct sigaction act = {
                        .sa_flags     = SA_SIGINFO,
                        .sa_sigaction = exec_error,
                };
                sigaction(SIGUSR1, &act, NULL);
        }

        if (target__none(target)) {
                if (evlist->core.threads == NULL) {
                        fprintf(stderr, "FATAL: evlist->threads need to be set at this point (%s:%d).\n",
                                __func__, __LINE__);
                        goto out_close_pipes;
                }
                perf_thread_map__set_pid(evlist->core.threads, 0, evlist->workload.pid);
        }

        close(child_ready_pipe[1]);
        close(go_pipe[0]);
        /*
         * wait for child to settle
         */
        if (read(child_ready_pipe[0], &bf, 1) == -1) {
                perror("unable to read pipe");
                goto out_close_pipes;
        }

        fcntl(go_pipe[1], F_SETFD, FD_CLOEXEC);
        evlist->workload.cork_fd = go_pipe[1];
        close(child_ready_pipe[0]);
        return 0;

out_close_pipes:
        close(go_pipe[0]);
        close(go_pipe[1]);
out_close_ready_pipe:
        close(child_ready_pipe[0]);
        close(child_ready_pipe[1]);
        return -1;
}

int perf_evlist__start_workload(struct evlist *evlist)
{
        if (evlist->workload.cork_fd > 0) {
                char bf = 0;
                int ret;
                /*
                 * Remove the cork, let it rip!
                 */
                ret = write(evlist->workload.cork_fd, &bf, 1);
                if (ret < 0)
                        perror("unable to write to pipe");

                close(evlist->workload.cork_fd);
                return ret;
        }

        return 0;
}

int perf_evlist__parse_sample(struct evlist *evlist, union perf_event *event,
                              struct perf_sample *sample)
{
        struct evsel *evsel = perf_evlist__event2evsel(evlist, event);

        if (!evsel)
                return -EFAULT;
        return evsel__parse_sample(evsel, event, sample);
}

int perf_evlist__parse_sample_timestamp(struct evlist *evlist,
                                        union perf_event *event,
                                        u64 *timestamp)
{
        struct evsel *evsel = perf_evlist__event2evsel(evlist, event);

        if (!evsel)
                return -EFAULT;
        return evsel__parse_sample_timestamp(evsel, event, timestamp);
}

int evlist__strerror_open(struct evlist *evlist, int err, char *buf, size_t size)
{
        int printed, value;
        char sbuf[STRERR_BUFSIZE], *emsg = str_error_r(err, sbuf, sizeof(sbuf));

        switch (err) {
        case EACCES:
        case EPERM:
                printed = scnprintf(buf, size,
                                    "Error:\t%s.\n"
                                    "Hint:\tCheck /proc/sys/kernel/perf_event_paranoid setting.", emsg);

                value = perf_event_paranoid();

                printed += scnprintf(buf + printed, size - printed, "\nHint:\t");

                if (value >= 2) {
                        printed += scnprintf(buf + printed, size - printed,
                                             "For your workloads it needs to be <= 1\nHint:\t");
                }
                printed += scnprintf(buf + printed, size - printed,
                                     "For system wide tracing it needs to be set to -1.\n");

                printed += scnprintf(buf + printed, size - printed,
                                    "Hint:\tTry: 'sudo sh -c \"echo -1 > /proc/sys/kernel/perf_event_paranoid\"'\n"
                                    "Hint:\tThe current value is %d.", value);
                break;
        case EINVAL: {
                struct evsel *first = evlist__first(evlist);
                int max_freq;

                if (sysctl__read_int("kernel/perf_event_max_sample_rate", &max_freq) < 0)
                        goto out_default;

                if (first->core.attr.sample_freq < (u64)max_freq)
                        goto out_default;

                printed = scnprintf(buf, size,
                                    "Error:\t%s.\n"
                                    "Hint:\tCheck /proc/sys/kernel/perf_event_max_sample_rate.\n"
                                    "Hint:\tThe current value is %d and %" PRIu64 " is being requested.",
                                    emsg, max_freq, first->core.attr.sample_freq);
                break;
        }
        default:
out_default:
                scnprintf(buf, size, "%s", emsg);
                break;
        }

        return 0;
}

int evlist__strerror_mmap(struct evlist *evlist, int err, char *buf, size_t size)
{
        char sbuf[STRERR_BUFSIZE], *emsg = str_error_r(err, sbuf, sizeof(sbuf));
        int pages_attempted = evlist->core.mmap_len / 1024, pages_max_per_user, printed = 0;

        switch (err) {
        case EPERM:
                sysctl__read_int("kernel/perf_event_mlock_kb", &pages_max_per_user);
                printed += scnprintf(buf + printed, size - printed,
                                     "Error:\t%s.\n"
                                     "Hint:\tCheck /proc/sys/kernel/perf_event_mlock_kb (%d kB) setting.\n"
                                     "Hint:\tTried using %zd kB.\n",
                                     emsg, pages_max_per_user, pages_attempted);

                if (pages_attempted >= pages_max_per_user) {
                        printed += scnprintf(buf + printed, size - printed,
                                             "Hint:\tTry 'sudo sh -c \"echo %d > /proc/sys/kernel/perf_event_mlock_kb\"', or\n",
                                             pages_max_per_user + pages_attempted);
                }

                printed += scnprintf(buf + printed, size - printed,
                                     "Hint:\tTry using a smaller -m/--mmap-pages value.");
                break;
        default:
                scnprintf(buf, size, "%s", emsg);
                break;
        }

        return 0;
}

void perf_evlist__to_front(struct evlist *evlist,
                           struct evsel *move_evsel)
{
        struct evsel *evsel, *n;
        LIST_HEAD(move);

        if (move_evsel == evlist__first(evlist))
                return;

        evlist__for_each_entry_safe(evlist, n, evsel) {
                if (evsel->leader == move_evsel->leader)
                        list_move_tail(&evsel->core.node, &move);
        }

        list_splice(&move, &evlist->core.entries);
}

struct evsel *perf_evlist__get_tracking_event(struct evlist *evlist)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel->tracking)
                        return evsel;
        }

        return evlist__first(evlist);
}

void perf_evlist__set_tracking_event(struct evlist *evlist,
                                     struct evsel *tracking_evsel)
{
        struct evsel *evsel;

        if (tracking_evsel->tracking)
                return;

        evlist__for_each_entry(evlist, evsel) {
                if (evsel != tracking_evsel)
                        evsel->tracking = false;
        }

        tracking_evsel->tracking = true;
}

struct evsel *
perf_evlist__find_evsel_by_str(struct evlist *evlist,
                               const char *str)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if (!evsel->name)
                        continue;
                if (strcmp(str, evsel->name) == 0)
                        return evsel;
        }

        return NULL;
}

void perf_evlist__toggle_bkw_mmap(struct evlist *evlist,
                                  enum bkw_mmap_state state)
{
        enum bkw_mmap_state old_state = evlist->bkw_mmap_state;
        enum action {
                NONE,
                PAUSE,
                RESUME,
        } action = NONE;

        if (!evlist->overwrite_mmap)
                return;

        switch (old_state) {
        case BKW_MMAP_NOTREADY: {
                if (state != BKW_MMAP_RUNNING)
                        goto state_err;
                break;
        }
        case BKW_MMAP_RUNNING: {
                if (state != BKW_MMAP_DATA_PENDING)
                        goto state_err;
                action = PAUSE;
                break;
        }
        case BKW_MMAP_DATA_PENDING: {
                if (state != BKW_MMAP_EMPTY)
                        goto state_err;
                break;
        }
        case BKW_MMAP_EMPTY: {
                if (state != BKW_MMAP_RUNNING)
                        goto state_err;
                action = RESUME;
                break;
        }
        default:
                WARN_ONCE(1, "Shouldn't get there\n");
        }

        evlist->bkw_mmap_state = state;

        switch (action) {
        case PAUSE:
                perf_evlist__pause(evlist);
                break;
        case RESUME:
                perf_evlist__resume(evlist);
                break;
        case NONE:
        default:
                break;
        }

state_err:
        return;
}

bool perf_evlist__exclude_kernel(struct evlist *evlist)
{
        struct evsel *evsel;

        evlist__for_each_entry(evlist, evsel) {
                if (!evsel->core.attr.exclude_kernel)
                        return false;
        }

        return true;
}

/*
 * Events in data file are not collect in groups, but we still want
 * the group display. Set the artificial group and set the leader's
 * forced_leader flag to notify the display code.
 */
void perf_evlist__force_leader(struct evlist *evlist)
{
        if (!evlist->nr_groups) {
                struct evsel *leader = evlist__first(evlist);

                perf_evlist__set_leader(evlist);
                leader->forced_leader = true;
        }
}

struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list,
                                                 struct evsel *evsel,
                                                bool close)
{
        struct evsel *c2, *leader;
        bool is_open = true;

        leader = evsel->leader;
        pr_debug("Weak group for %s/%d failed\n",
                        leader->name, leader->core.nr_members);

        /*
         * for_each_group_member doesn't work here because it doesn't
         * include the first entry.
         */
        evlist__for_each_entry(evsel_list, c2) {
                if (c2 == evsel)
                        is_open = false;
                if (c2->leader == leader) {
                        if (is_open && close)
                                perf_evsel__close(&c2->core);
                        c2->leader = c2;
                        c2->core.nr_members = 0;
                        /*
                         * Set this for all former members of the group
                         * to indicate they get reopened.
                         */
                        c2->reset_group = true;
                }
        }
        return leader;
}

int evlist__initialize_ctlfd(struct evlist *evlist, int fd, int ack)
{
        if (fd == -1) {
                pr_debug("Control descriptor is not initialized\n");
                return 0;
        }

        evlist->ctl_fd.pos = perf_evlist__add_pollfd(&evlist->core, fd, NULL, POLLIN,
                                                     fdarray_flag__nonfilterable);
        if (evlist->ctl_fd.pos < 0) {
                evlist->ctl_fd.pos = -1;
                pr_err("Failed to add ctl fd entry: %m\n");
                return -1;
        }

        evlist->ctl_fd.fd = fd;
        evlist->ctl_fd.ack = ack;

        return 0;
}

bool evlist__ctlfd_initialized(struct evlist *evlist)
{
        return evlist->ctl_fd.pos >= 0;
}

int evlist__finalize_ctlfd(struct evlist *evlist)
{
        struct pollfd *entries = evlist->core.pollfd.entries;

        if (!evlist__ctlfd_initialized(evlist))
                return 0;

        entries[evlist->ctl_fd.pos].fd = -1;
        entries[evlist->ctl_fd.pos].events = 0;
        entries[evlist->ctl_fd.pos].revents = 0;

        evlist->ctl_fd.pos = -1;
        evlist->ctl_fd.ack = -1;
        evlist->ctl_fd.fd = -1;

        return 0;
}

static int evlist__ctlfd_recv(struct evlist *evlist, enum evlist_ctl_cmd *cmd,
                              char *cmd_data, size_t data_size)
{
        int err;
        char c;
        size_t bytes_read = 0;

        memset(cmd_data, 0, data_size);
        data_size--;

        do {
                err = read(evlist->ctl_fd.fd, &c, 1);
                if (err > 0) {
                        if (c == '\n' || c == '\0')
                                break;
                        cmd_data[bytes_read++] = c;
                        if (bytes_read == data_size)
                                break;
                } else {
                        if (err == -1)
                                pr_err("Failed to read from ctlfd %d: %m\n", evlist->ctl_fd.fd);
                        break;
                }
        } while (1);

        pr_debug("Message from ctl_fd: \"%s%s\"\n", cmd_data,
                 bytes_read == data_size ? "" : c == '\n' ? "\\n" : "\\0");

        if (err > 0) {
                if (!strncmp(cmd_data, EVLIST_CTL_CMD_ENABLE_TAG,
                             (sizeof(EVLIST_CTL_CMD_ENABLE_TAG)-1))) {
                        *cmd = EVLIST_CTL_CMD_ENABLE;
                } else if (!strncmp(cmd_data, EVLIST_CTL_CMD_DISABLE_TAG,
                                    (sizeof(EVLIST_CTL_CMD_DISABLE_TAG)-1))) {
                        *cmd = EVLIST_CTL_CMD_DISABLE;
                }
        }

        return err;
}

static int evlist__ctlfd_ack(struct evlist *evlist)
{
        int err;

        if (evlist->ctl_fd.ack == -1)
                return 0;

        err = write(evlist->ctl_fd.ack, EVLIST_CTL_CMD_ACK_TAG,
                    sizeof(EVLIST_CTL_CMD_ACK_TAG));
        if (err == -1)
                pr_err("failed to write to ctl_ack_fd %d: %m\n", evlist->ctl_fd.ack);

        return err;
}

int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)
{
        int err = 0;
        char cmd_data[EVLIST_CTL_CMD_MAX_LEN];
        int ctlfd_pos = evlist->ctl_fd.pos;
        struct pollfd *entries = evlist->core.pollfd.entries;

        if (!evlist__ctlfd_initialized(evlist) || !entries[ctlfd_pos].revents)
                return 0;

        if (entries[ctlfd_pos].revents & POLLIN) {
                err = evlist__ctlfd_recv(evlist, cmd, cmd_data,
                                         EVLIST_CTL_CMD_MAX_LEN);
                if (err > 0) {
                        switch (*cmd) {
                        case EVLIST_CTL_CMD_ENABLE:
                                evlist__enable(evlist);
                                break;
                        case EVLIST_CTL_CMD_DISABLE:
                                evlist__disable(evlist);
                                break;
                        case EVLIST_CTL_CMD_ACK:
                        case EVLIST_CTL_CMD_UNSUPPORTED:
                        default:
                                pr_debug("ctlfd: unsupported %d\n", *cmd);
                                break;
                        }
                        if (!(*cmd == EVLIST_CTL_CMD_ACK || *cmd == EVLIST_CTL_CMD_UNSUPPORTED))
                                evlist__ctlfd_ack(evlist);
                }
        }

        if (entries[ctlfd_pos].revents & (POLLHUP | POLLERR))
                evlist__finalize_ctlfd(evlist);
        else
                entries[ctlfd_pos].revents = 0;

        return err;
}