// SPDX-License-Identifier: GPL-2.0-only
#include <errno.h>
#include <perf/cpumap.h>
#include <stdlib.h>
#include <linux/refcount.h>
#include <internal/cpumap.h>
#include <asm/bug.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <limits.h>
#include "internal.h"
#include <api/fs/fs.h>

#define MAX_NR_CPUS 4096

void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus)
{
        RC_CHK_ACCESS(map)->nr = nr_cpus;
}

struct perf_cpu_map *perf_cpu_map__alloc(int nr_cpus)
{
        RC_STRUCT(perf_cpu_map) *cpus;
        struct perf_cpu_map *result;

        if (nr_cpus == 0)
                return NULL;

        cpus = malloc(sizeof(*cpus) + sizeof(struct perf_cpu) * nr_cpus);
        if (ADD_RC_CHK(result, cpus)) {
                cpus->nr = nr_cpus;
                refcount_set(&cpus->refcnt, 1);
        }
        return result;
}

struct perf_cpu_map *perf_cpu_map__new_any_cpu(void)
{
        struct perf_cpu_map *cpus = perf_cpu_map__alloc(1);

        if (cpus)
                RC_CHK_ACCESS(cpus)->map[0].cpu = -1;

        return cpus;
}

static void cpu_map__delete(struct perf_cpu_map *map)
{
        if (map) {
                WARN_ONCE(refcount_read(perf_cpu_map__refcnt(map)) != 0,
                          "cpu_map refcnt unbalanced\n");
                RC_CHK_FREE(map);
        }
}

struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map)
{
        struct perf_cpu_map *result;

        if (RC_CHK_GET(result, map))
                refcount_inc(perf_cpu_map__refcnt(map));

        return result;
}

void perf_cpu_map__put(struct perf_cpu_map *map)
{
        if (map) {
                if (refcount_dec_and_test(perf_cpu_map__refcnt(map)))
                        cpu_map__delete(map);
                else
                        RC_CHK_PUT(map);
        }
}

static struct perf_cpu_map *cpu_map__new_sysconf(void)
{
        struct perf_cpu_map *cpus;
        int nr_cpus, nr_cpus_conf;

        nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
        if (nr_cpus < 0)
                return NULL;

        nr_cpus_conf = sysconf(_SC_NPROCESSORS_CONF);
        if (nr_cpus != nr_cpus_conf) {
                pr_warning("Number of online CPUs (%d) differs from the number configured (%d) the CPU map will only cover the first %d CPUs.",
                        nr_cpus, nr_cpus_conf, nr_cpus);
        }

        cpus = perf_cpu_map__alloc(nr_cpus);
        if (cpus != NULL) {
                int i;

                for (i = 0; i < nr_cpus; ++i)
                        RC_CHK_ACCESS(cpus)->map[i].cpu = i;
        }

        return cpus;
}

static struct perf_cpu_map *cpu_map__new_sysfs_online(void)
{
        struct perf_cpu_map *cpus = NULL;
        char *buf = NULL;
        size_t buf_len;

        if (sysfs__read_str("devices/system/cpu/online", &buf, &buf_len) >= 0) {
                cpus = perf_cpu_map__new(buf);
                free(buf);
        }
        return cpus;
}

struct perf_cpu_map *perf_cpu_map__new_online_cpus(void)
{
        struct perf_cpu_map *cpus = cpu_map__new_sysfs_online();

        if (cpus)
                return cpus;

        return cpu_map__new_sysconf();
}


static int cmp_cpu(const void *a, const void *b)
{
        const struct perf_cpu *cpu_a = a, *cpu_b = b;

        return cpu_a->cpu - cpu_b->cpu;
}

static struct perf_cpu __perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx)
{
        return RC_CHK_ACCESS(cpus)->map[idx];
}

static struct perf_cpu_map *cpu_map__trim_new(int nr_cpus, const struct perf_cpu *tmp_cpus)
{
        size_t payload_size = nr_cpus * sizeof(struct perf_cpu);
        struct perf_cpu_map *cpus = perf_cpu_map__alloc(nr_cpus);
        int i, j;

        if (cpus != NULL) {
                memcpy(RC_CHK_ACCESS(cpus)->map, tmp_cpus, payload_size);
                qsort(RC_CHK_ACCESS(cpus)->map, nr_cpus, sizeof(struct perf_cpu), cmp_cpu);
                /* Remove dups */
                j = 0;
                for (i = 0; i < nr_cpus; i++) {
                        if (i == 0 ||
                            __perf_cpu_map__cpu(cpus, i).cpu !=
                            __perf_cpu_map__cpu(cpus, i - 1).cpu) {
                                RC_CHK_ACCESS(cpus)->map[j++].cpu =
                                        __perf_cpu_map__cpu(cpus, i).cpu;
                        }
                }
                perf_cpu_map__set_nr(cpus, j);
                assert(j <= nr_cpus);
        }
        return cpus;
}

struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
{
        struct perf_cpu_map *cpus = NULL;
        unsigned long start_cpu, end_cpu = 0;
        char *p = NULL;
        int i, nr_cpus = 0;
        struct perf_cpu *tmp_cpus = NULL, *tmp;
        int max_entries = 0;

        if (!cpu_list)
                return perf_cpu_map__new_online_cpus();

        /*
         * must handle the case of empty cpumap to cover
         * TOPOLOGY header for NUMA nodes with no CPU
         * ( e.g., because of CPU hotplug)
         */
        if (!isdigit(*cpu_list) && *cpu_list != '\0')
                goto out;

        while (isdigit(*cpu_list)) {
                p = NULL;
                start_cpu = strtoul(cpu_list, &p, 0);
                if (start_cpu >= INT16_MAX
                    || (*p != '\0' && *p != ',' && *p != '-' && *p != '\n'))
                        goto invalid;

                if (*p == '-') {
                        cpu_list = ++p;
                        p = NULL;
                        end_cpu = strtoul(cpu_list, &p, 0);

                        if (end_cpu >= INT16_MAX || (*p != '\0' && *p != ',' && *p != '\n'))
                                goto invalid;

                        if (end_cpu < start_cpu)
                                goto invalid;
                } else {
                        end_cpu = start_cpu;
                }

                WARN_ONCE(end_cpu >= MAX_NR_CPUS, "Perf can support %d CPUs. "
                                                  "Consider raising MAX_NR_CPUS\n", MAX_NR_CPUS);

                for (; start_cpu <= end_cpu; start_cpu++) {
                        /* check for duplicates */
                        for (i = 0; i < nr_cpus; i++)
                                if (tmp_cpus[i].cpu == (int16_t)start_cpu)
                                        goto invalid;

                        if (nr_cpus == max_entries) {
                                max_entries += max(end_cpu - start_cpu + 1, 16UL);
                                tmp = realloc(tmp_cpus, max_entries * sizeof(struct perf_cpu));
                                if (tmp == NULL)
                                        goto invalid;
                                tmp_cpus = tmp;
                        }
                        tmp_cpus[nr_cpus++].cpu = (int16_t)start_cpu;
                }
                if (*p)
                        ++p;

                cpu_list = p;
        }

        if (nr_cpus > 0) {
                cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
        } else if (*cpu_list != '\0') {
                pr_warning("Unexpected characters at end of cpu list ('%s'), using online CPUs.",
                           cpu_list);
                cpus = perf_cpu_map__new_online_cpus();
        } else {
                cpus = perf_cpu_map__new_any_cpu();
        }
invalid:
        free(tmp_cpus);
out:
        return cpus;
}

struct perf_cpu_map *perf_cpu_map__new_int(int cpu)
{
        struct perf_cpu_map *cpus = perf_cpu_map__alloc(1);

        if (cpus)
                RC_CHK_ACCESS(cpus)->map[0].cpu = cpu;

        return cpus;
}

static int __perf_cpu_map__nr(const struct perf_cpu_map *cpus)
{
        return RC_CHK_ACCESS(cpus)->nr;
}

struct perf_cpu perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx)
{
        struct perf_cpu result = {
                .cpu = -1
        };

        if (cpus && idx < __perf_cpu_map__nr(cpus))
                return __perf_cpu_map__cpu(cpus, idx);

        return result;
}

int perf_cpu_map__nr(const struct perf_cpu_map *cpus)
{
        return cpus ? __perf_cpu_map__nr(cpus) : 1;
}

bool perf_cpu_map__has_any_cpu_or_is_empty(const struct perf_cpu_map *map)
{
        return map ? __perf_cpu_map__cpu(map, 0).cpu == -1 : true;
}

bool perf_cpu_map__is_any_cpu_or_is_empty(const struct perf_cpu_map *map)
{
        if (!map)
                return true;

        return __perf_cpu_map__nr(map) == 1 && __perf_cpu_map__cpu(map, 0).cpu == -1;
}

bool perf_cpu_map__is_empty(const struct perf_cpu_map *map)
{
        return map == NULL;
}

int perf_cpu_map__idx(const struct perf_cpu_map *cpus, struct perf_cpu cpu)
{
        int low, high;

        if (!cpus)
                return -1;

        low = 0;
        high = __perf_cpu_map__nr(cpus);
        while (low < high) {
                int idx = (low + high) / 2;
                struct perf_cpu cpu_at_idx = __perf_cpu_map__cpu(cpus, idx);

                if (cpu_at_idx.cpu == cpu.cpu)
                        return idx;

                if (cpu_at_idx.cpu > cpu.cpu)
                        high = idx;
                else
                        low = idx + 1;
        }

        return -1;
}

bool perf_cpu_map__has(const struct perf_cpu_map *cpus, struct perf_cpu cpu)
{
        return perf_cpu_map__idx(cpus, cpu) != -1;
}

bool perf_cpu_map__equal(const struct perf_cpu_map *lhs, const struct perf_cpu_map *rhs)
{
        int nr;

        if (lhs == rhs)
                return true;

        if (!lhs || !rhs)
                return false;

        nr = __perf_cpu_map__nr(lhs);
        if (nr != __perf_cpu_map__nr(rhs))
                return false;

        for (int idx = 0; idx < nr; idx++) {
                if (__perf_cpu_map__cpu(lhs, idx).cpu != __perf_cpu_map__cpu(rhs, idx).cpu)
                        return false;
        }
        return true;
}

bool perf_cpu_map__has_any_cpu(const struct perf_cpu_map *map)
{
        return map && __perf_cpu_map__cpu(map, 0).cpu == -1;
}

struct perf_cpu perf_cpu_map__min(const struct perf_cpu_map *map)
{
        struct perf_cpu cpu, result = {
                .cpu = -1
        };
        int idx;

        perf_cpu_map__for_each_cpu_skip_any(cpu, idx, map) {
                result = cpu;
                break;
        }
        return result;
}

struct perf_cpu perf_cpu_map__max(const struct perf_cpu_map *map)
{
        struct perf_cpu result = {
                .cpu = -1
        };

        if (!map)
                return result;

        // The CPUs are always sorted and nr is always > 0 as 0 length map is
        // encoded as NULL.
        return __perf_cpu_map__cpu(map, __perf_cpu_map__nr(map) - 1);
}

/** Is 'b' a subset of 'a'. */
bool perf_cpu_map__is_subset(const struct perf_cpu_map *a, const struct perf_cpu_map *b)
{
        if (a == b || !b)
                return true;
        if (!a || __perf_cpu_map__nr(b) > __perf_cpu_map__nr(a))
                return false;

        for (int i = 0, j = 0; i < __perf_cpu_map__nr(a); i++) {
                if (__perf_cpu_map__cpu(a, i).cpu > __perf_cpu_map__cpu(b, j).cpu)
                        return false;
                if (__perf_cpu_map__cpu(a, i).cpu == __perf_cpu_map__cpu(b, j).cpu) {
                        j++;
                        if (j == __perf_cpu_map__nr(b))
                                return true;
                }
        }
        return false;
}

/*
 * Merge two cpumaps.
 *
 * If 'other' is subset of '*orig', '*orig' keeps itself with no reference count
 * change (similar to "realloc").
 *
 * If '*orig' is subset of 'other', '*orig' reuses 'other' with its reference
 * count increased.
 *
 * Otherwise, '*orig' gets freed and replaced with a new map.
 */
int perf_cpu_map__merge(struct perf_cpu_map **orig, struct perf_cpu_map *other)
{
        struct perf_cpu *tmp_cpus;
        int tmp_len;
        int i, j, k;
        struct perf_cpu_map *merged;

        if (perf_cpu_map__is_subset(*orig, other))
                return 0;
        if (perf_cpu_map__is_subset(other, *orig)) {
                perf_cpu_map__put(*orig);
                *orig = perf_cpu_map__get(other);
                return 0;
        }

        tmp_len = __perf_cpu_map__nr(*orig) + __perf_cpu_map__nr(other);
        tmp_cpus = malloc(tmp_len * sizeof(struct perf_cpu));
        if (!tmp_cpus)
                return -ENOMEM;

        /* Standard merge algorithm from wikipedia */
        i = j = k = 0;
        while (i < __perf_cpu_map__nr(*orig) && j < __perf_cpu_map__nr(other)) {
                if (__perf_cpu_map__cpu(*orig, i).cpu <= __perf_cpu_map__cpu(other, j).cpu) {
                        if (__perf_cpu_map__cpu(*orig, i).cpu == __perf_cpu_map__cpu(other, j).cpu)
                                j++;
                        tmp_cpus[k++] = __perf_cpu_map__cpu(*orig, i++);
                } else
                        tmp_cpus[k++] = __perf_cpu_map__cpu(other, j++);
        }

        while (i < __perf_cpu_map__nr(*orig))
                tmp_cpus[k++] = __perf_cpu_map__cpu(*orig, i++);

        while (j < __perf_cpu_map__nr(other))
                tmp_cpus[k++] = __perf_cpu_map__cpu(other, j++);
        assert(k <= tmp_len);

        merged = cpu_map__trim_new(k, tmp_cpus);
        free(tmp_cpus);
        perf_cpu_map__put(*orig);
        *orig = merged;
        return 0;
}

struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *orig,
                                             struct perf_cpu_map *other)
{
        int i, j, k;
        struct perf_cpu_map *merged;

        if (perf_cpu_map__is_subset(other, orig))
                return perf_cpu_map__get(orig);
        if (perf_cpu_map__is_subset(orig, other))
                return perf_cpu_map__get(other);

        i = j = k = 0;
        while (i < __perf_cpu_map__nr(orig) && j < __perf_cpu_map__nr(other)) {
                if (__perf_cpu_map__cpu(orig, i).cpu < __perf_cpu_map__cpu(other, j).cpu)
                        i++;
                else if (__perf_cpu_map__cpu(orig, i).cpu > __perf_cpu_map__cpu(other, j).cpu)
                        j++;
                else { /* CPUs match. */
                        i++;
                        j++;
                        k++;
                }
        }
        if (k == 0) /* Maps are completely disjoint. */
                return NULL;

        merged = perf_cpu_map__alloc(k);
        if (!merged)
                return NULL;
        /* Entries are added to merged in sorted order, so no need to sort again. */
        i = j = k = 0;
        while (i < __perf_cpu_map__nr(orig) && j < __perf_cpu_map__nr(other)) {
                if (__perf_cpu_map__cpu(orig, i).cpu < __perf_cpu_map__cpu(other, j).cpu)
                        i++;
                else if (__perf_cpu_map__cpu(orig, i).cpu > __perf_cpu_map__cpu(other, j).cpu)
                        j++;
                else {
                        j++;
                        RC_CHK_ACCESS(merged)->map[k++] = __perf_cpu_map__cpu(orig, i++);
                }
        }
        return merged;
}