// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011-2017, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Parts came from evlist.c builtin-{top,stat,record}.c, see those files for further
 * copyright notes.
 */

#include <sys/mman.h>
#include <inttypes.h>
#include <asm/bug.h>
#include <linux/zalloc.h>
#ifdef HAVE_LIBNUMA_SUPPORT
#include <numaif.h>
#endif
#include "debug.h"
#include "event.h"
#include "mmap.h"
#include "util.h" /* page_size */

size_t perf_mmap__mmap_len(struct perf_mmap *map)
{
        return map->mask + 1 + page_size;
}

/* When check_messup is true, 'end' must points to a good entry */
static union perf_event *perf_mmap__read(struct perf_mmap *map,
                                         u64 *startp, u64 end)
{
        unsigned char *data = map->base + page_size;
        union perf_event *event = NULL;
        int diff = end - *startp;

        if (diff >= (int)sizeof(event->header)) {
                size_t size;

                event = (union perf_event *)&data[*startp & map->mask];
                size = event->header.size;

                if (size < sizeof(event->header) || diff < (int)size)
                        return NULL;

                /*
                 * Event straddles the mmap boundary -- header should always
                 * be inside due to u64 alignment of output.
                 */
                if ((*startp & map->mask) + size != ((*startp + size) & map->mask)) {
                        unsigned int offset = *startp;
                        unsigned int len = min(sizeof(*event), size), cpy;
                        void *dst = map->event_copy;

                        do {
                                cpy = min(map->mask + 1 - (offset & map->mask), len);
                                memcpy(dst, &data[offset & map->mask], cpy);
                                offset += cpy;
                                dst += cpy;
                                len -= cpy;
                        } while (len);

                        event = (union perf_event *)map->event_copy;
                }

                *startp += size;
        }

        return event;
}

/*
 * Read event from ring buffer one by one.
 * Return one event for each call.
 *
 * Usage:
 * perf_mmap__read_init()
 * while(event = perf_mmap__read_event()) {
 *      //process the event
 *      perf_mmap__consume()
 * }
 * perf_mmap__read_done()
 */
union perf_event *perf_mmap__read_event(struct perf_mmap *map)
{
        union perf_event *event;

        /*
         * Check if event was unmapped due to a POLLHUP/POLLERR.
         */
        if (!refcount_read(&map->refcnt))
                return NULL;

        /* non-overwirte doesn't pause the ringbuffer */
        if (!map->overwrite)
                map->end = perf_mmap__read_head(map);

        event = perf_mmap__read(map, &map->start, map->end);

        if (!map->overwrite)
                map->prev = map->start;

        return event;
}

static bool perf_mmap__empty(struct perf_mmap *map)
{
        return perf_mmap__read_head(map) == map->prev && !map->auxtrace_mmap.base;
}

void perf_mmap__get(struct perf_mmap *map)
{
        refcount_inc(&map->refcnt);
}

void perf_mmap__put(struct perf_mmap *map)
{
        BUG_ON(map->base && refcount_read(&map->refcnt) == 0);

        if (refcount_dec_and_test(&map->refcnt))
                perf_mmap__munmap(map);
}

void perf_mmap__consume(struct perf_mmap *map)
{
        if (!map->overwrite) {
                u64 old = map->prev;

                perf_mmap__write_tail(map, old);
        }

        if (refcount_read(&map->refcnt) == 1 && perf_mmap__empty(map))
                perf_mmap__put(map);
}

int __weak auxtrace_mmap__mmap(struct auxtrace_mmap *mm __maybe_unused,
                               struct auxtrace_mmap_params *mp __maybe_unused,
                               void *userpg __maybe_unused,
                               int fd __maybe_unused)
{
        return 0;
}

void __weak auxtrace_mmap__munmap(struct auxtrace_mmap *mm __maybe_unused)
{
}

void __weak auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp __maybe_unused,
                                       off_t auxtrace_offset __maybe_unused,
                                       unsigned int auxtrace_pages __maybe_unused,
                                       bool auxtrace_overwrite __maybe_unused)
{
}

void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __maybe_unused,
                                          struct perf_evlist *evlist __maybe_unused,
                                          int idx __maybe_unused,
                                          bool per_cpu __maybe_unused)
{
}

#ifdef HAVE_AIO_SUPPORT
static int perf_mmap__aio_enabled(struct perf_mmap *map)
{
        return map->aio.nr_cblocks > 0;
}

#ifdef HAVE_LIBNUMA_SUPPORT
static int perf_mmap__aio_alloc(struct perf_mmap *map, int idx)
{
        map->aio.data[idx] = mmap(NULL, perf_mmap__mmap_len(map), PROT_READ|PROT_WRITE,
                                  MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
        if (map->aio.data[idx] == MAP_FAILED) {
                map->aio.data[idx] = NULL;
                return -1;
        }

        return 0;
}

static void perf_mmap__aio_free(struct perf_mmap *map, int idx)
{
        if (map->aio.data[idx]) {
                munmap(map->aio.data[idx], perf_mmap__mmap_len(map));
                map->aio.data[idx] = NULL;
        }
}

static int perf_mmap__aio_bind(struct perf_mmap *map, int idx, int cpu, int affinity)
{
        void *data;
        size_t mmap_len;
        unsigned long node_mask;

        if (affinity != PERF_AFFINITY_SYS && cpu__max_node() > 1) {
                data = map->aio.data[idx];
                mmap_len = perf_mmap__mmap_len(map);
                node_mask = 1UL << cpu__get_node(cpu);
                if (mbind(data, mmap_len, MPOL_BIND, &node_mask, 1, 0)) {
                        pr_err("Failed to bind [%p-%p] AIO buffer to node %d: error %m\n",
                                data, data + mmap_len, cpu__get_node(cpu));
                        return -1;
                }
        }

        return 0;
}
#else /* !HAVE_LIBNUMA_SUPPORT */
static int perf_mmap__aio_alloc(struct perf_mmap *map, int idx)
{
        map->aio.data[idx] = malloc(perf_mmap__mmap_len(map));
        if (map->aio.data[idx] == NULL)
                return -1;

        return 0;
}

static void perf_mmap__aio_free(struct perf_mmap *map, int idx)
{
        zfree(&(map->aio.data[idx]));
}

static int perf_mmap__aio_bind(struct perf_mmap *map __maybe_unused, int idx __maybe_unused,
                int cpu __maybe_unused, int affinity __maybe_unused)
{
        return 0;
}
#endif

static int perf_mmap__aio_mmap(struct perf_mmap *map, struct mmap_params *mp)
{
        int delta_max, i, prio, ret;

        map->aio.nr_cblocks = mp->nr_cblocks;
        if (map->aio.nr_cblocks) {
                map->aio.aiocb = calloc(map->aio.nr_cblocks, sizeof(struct aiocb *));
                if (!map->aio.aiocb) {
                        pr_debug2("failed to allocate aiocb for data buffer, error %m\n");
                        return -1;
                }
                map->aio.cblocks = calloc(map->aio.nr_cblocks, sizeof(struct aiocb));
                if (!map->aio.cblocks) {
                        pr_debug2("failed to allocate cblocks for data buffer, error %m\n");
                        return -1;
                }
                map->aio.data = calloc(map->aio.nr_cblocks, sizeof(void *));
                if (!map->aio.data) {
                        pr_debug2("failed to allocate data buffer, error %m\n");
                        return -1;
                }
                delta_max = sysconf(_SC_AIO_PRIO_DELTA_MAX);
                for (i = 0; i < map->aio.nr_cblocks; ++i) {
                        ret = perf_mmap__aio_alloc(map, i);
                        if (ret == -1) {
                                pr_debug2("failed to allocate data buffer area, error %m");
                                return -1;
                        }
                        ret = perf_mmap__aio_bind(map, i, map->cpu, mp->affinity);
                        if (ret == -1)
                                return -1;
                        /*
                         * Use cblock.aio_fildes value different from -1
                         * to denote started aio write operation on the
                         * cblock so it requires explicit record__aio_sync()
                         * call prior the cblock may be reused again.
                         */
                        map->aio.cblocks[i].aio_fildes = -1;
                        /*
                         * Allocate cblocks with priority delta to have
                         * faster aio write system calls because queued requests
                         * are kept in separate per-prio queues and adding
                         * a new request will iterate thru shorter per-prio
                         * list. Blocks with numbers higher than
                         *  _SC_AIO_PRIO_DELTA_MAX go with priority 0.
                         */
                        prio = delta_max - i;
                        map->aio.cblocks[i].aio_reqprio = prio >= 0 ? prio : 0;
                }
        }

        return 0;
}

static void perf_mmap__aio_munmap(struct perf_mmap *map)
{
        int i;

        for (i = 0; i < map->aio.nr_cblocks; ++i)
                perf_mmap__aio_free(map, i);
        if (map->aio.data)
                zfree(&map->aio.data);
        zfree(&map->aio.cblocks);
        zfree(&map->aio.aiocb);
}
#else /* !HAVE_AIO_SUPPORT */
static int perf_mmap__aio_enabled(struct perf_mmap *map __maybe_unused)
{
        return 0;
}

static int perf_mmap__aio_mmap(struct perf_mmap *map __maybe_unused,
                               struct mmap_params *mp __maybe_unused)
{
        return 0;
}

static void perf_mmap__aio_munmap(struct perf_mmap *map __maybe_unused)
{
}
#endif

void perf_mmap__munmap(struct perf_mmap *map)
{
        perf_mmap__aio_munmap(map);
        if (map->data != NULL) {
                munmap(map->data, perf_mmap__mmap_len(map));
                map->data = NULL;
        }
        if (map->base != NULL) {
                munmap(map->base, perf_mmap__mmap_len(map));
                map->base = NULL;
                map->fd = -1;
                refcount_set(&map->refcnt, 0);
        }
        auxtrace_mmap__munmap(&map->auxtrace_mmap);
}

static void build_node_mask(int node, cpu_set_t *mask)
{
        int c, cpu, nr_cpus;
        const struct cpu_map *cpu_map = NULL;

        cpu_map = cpu_map__online();
        if (!cpu_map)
                return;

        nr_cpus = cpu_map__nr(cpu_map);
        for (c = 0; c < nr_cpus; c++) {
                cpu = cpu_map->map[c]; /* map c index to online cpu index */
                if (cpu__get_node(cpu) == node)
                        CPU_SET(cpu, mask);
        }
}

static void perf_mmap__setup_affinity_mask(struct perf_mmap *map, struct mmap_params *mp)
{
        CPU_ZERO(&map->affinity_mask);
        if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
                build_node_mask(cpu__get_node(map->cpu), &map->affinity_mask);
        else if (mp->affinity == PERF_AFFINITY_CPU)
                CPU_SET(map->cpu, &map->affinity_mask);
}

int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu)
{
        /*
         * The last one will be done at perf_mmap__consume(), so that we
         * make sure we don't prevent tools from consuming every last event in
         * the ring buffer.
         *
         * I.e. we can get the POLLHUP meaning that the fd doesn't exist
         * anymore, but the last events for it are still in the ring buffer,
         * waiting to be consumed.
         *
         * Tools can chose to ignore this at their own discretion, but the
         * evlist layer can't just drop it when filtering events in
         * perf_evlist__filter_pollfd().
         */
        refcount_set(&map->refcnt, 2);
        map->prev = 0;
        map->mask = mp->mask;
        map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
                         MAP_SHARED, fd, 0);
        if (map->base == MAP_FAILED) {
                pr_debug2("failed to mmap perf event ring buffer, error %d\n",
                          errno);
                map->base = NULL;
                return -1;
        }
        map->fd = fd;
        map->cpu = cpu;

        perf_mmap__setup_affinity_mask(map, mp);

        map->flush = mp->flush;

        map->comp_level = mp->comp_level;

        if (map->comp_level && !perf_mmap__aio_enabled(map)) {
                map->data = mmap(NULL, perf_mmap__mmap_len(map), PROT_READ|PROT_WRITE,
                                 MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
                if (map->data == MAP_FAILED) {
                        pr_debug2("failed to mmap data buffer, error %d\n",
                                        errno);
                        map->data = NULL;
                        return -1;
                }
        }

        if (auxtrace_mmap__mmap(&map->auxtrace_mmap,
                                &mp->auxtrace_mp, map->base, fd))
                return -1;

        return perf_mmap__aio_mmap(map, mp);
}

static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
{
        struct perf_event_header *pheader;
        u64 evt_head = *start;
        int size = mask + 1;

        pr_debug2("%s: buf=%p, start=%"PRIx64"\n", __func__, buf, *start);
        pheader = (struct perf_event_header *)(buf + (*start & mask));
        while (true) {
                if (evt_head - *start >= (unsigned int)size) {
                        pr_debug("Finished reading overwrite ring buffer: rewind\n");
                        if (evt_head - *start > (unsigned int)size)
                                evt_head -= pheader->size;
                        *end = evt_head;
                        return 0;
                }

                pheader = (struct perf_event_header *)(buf + (evt_head & mask));

                if (pheader->size == 0) {
                        pr_debug("Finished reading overwrite ring buffer: get start\n");
                        *end = evt_head;
                        return 0;
                }

                evt_head += pheader->size;
                pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
        }
        WARN_ONCE(1, "Shouldn't get here\n");
        return -1;
}

/*
 * Report the start and end of the available data in ringbuffer
 */
static int __perf_mmap__read_init(struct perf_mmap *md)
{
        u64 head = perf_mmap__read_head(md);
        u64 old = md->prev;
        unsigned char *data = md->base + page_size;
        unsigned long size;

        md->start = md->overwrite ? head : old;
        md->end = md->overwrite ? old : head;

        if ((md->end - md->start) < md->flush)
                return -EAGAIN;

        size = md->end - md->start;
        if (size > (unsigned long)(md->mask) + 1) {
                if (!md->overwrite) {
                        WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n");

                        md->prev = head;
                        perf_mmap__consume(md);
                        return -EAGAIN;
                }

                /*
                 * Backward ring buffer is full. We still have a chance to read
                 * most of data from it.
                 */
                if (overwrite_rb_find_range(data, md->mask, &md->start, &md->end))
                        return -EINVAL;
        }

        return 0;
}

int perf_mmap__read_init(struct perf_mmap *map)
{
        /*
         * Check if event was unmapped due to a POLLHUP/POLLERR.
         */
        if (!refcount_read(&map->refcnt))
                return -ENOENT;

        return __perf_mmap__read_init(map);
}

int perf_mmap__push(struct perf_mmap *md, void *to,
                    int push(struct perf_mmap *map, void *to, void *buf, size_t size))
{
        u64 head = perf_mmap__read_head(md);
        unsigned char *data = md->base + page_size;
        unsigned long size;
        void *buf;
        int rc = 0;

        rc = perf_mmap__read_init(md);
        if (rc < 0)
                return (rc == -EAGAIN) ? 1 : -1;

        size = md->end - md->start;

        if ((md->start & md->mask) + size != (md->end & md->mask)) {
                buf = &data[md->start & md->mask];
                size = md->mask + 1 - (md->start & md->mask);
                md->start += size;

                if (push(md, to, buf, size) < 0) {
                        rc = -1;
                        goto out;
                }
        }

        buf = &data[md->start & md->mask];
        size = md->end - md->start;
        md->start += size;

        if (push(md, to, buf, size) < 0) {
                rc = -1;
                goto out;
        }

        md->prev = head;
        perf_mmap__consume(md);
out:
        return rc;
}

/*
 * Mandatory for overwrite mode
 * The direction of overwrite mode is backward.
 * The last perf_mmap__read() will set tail to map->prev.
 * Need to correct the map->prev to head which is the end of next read.
 */
void perf_mmap__read_done(struct perf_mmap *map)
{
        /*
         * Check if event was unmapped due to a POLLHUP/POLLERR.
         */
        if (!refcount_read(&map->refcnt))
                return;

        map->prev = perf_mmap__read_head(map);
}