io_uring: reset -EBUSY error when io sq thread is waken up

[thirdparty/linux.git] / kernel / bpf / arraymap.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016,2017 Facebook
 */
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/filter.h>
#include <linux/perf_event.h>
#include <uapi/linux/btf.h>

#include "map_in_map.h"

#define ARRAY_CREATE_FLAG_MASK \
        (BPF_F_NUMA_NODE | BPF_F_MMAPABLE | BPF_F_ACCESS_MASK)

static void bpf_array_free_percpu(struct bpf_array *array)
{
        int i;

        for (i = 0; i < array->map.max_entries; i++) {
                free_percpu(array->pptrs[i]);
                cond_resched();
        }
}

static int bpf_array_alloc_percpu(struct bpf_array *array)
{
        void __percpu *ptr;
        int i;

        for (i = 0; i < array->map.max_entries; i++) {
                ptr = __alloc_percpu_gfp(array->elem_size, 8,
                                         GFP_USER | __GFP_NOWARN);
                if (!ptr) {
                        bpf_array_free_percpu(array);
                        return -ENOMEM;
                }
                array->pptrs[i] = ptr;
                cond_resched();
        }

        return 0;
}

/* Called from syscall */
int array_map_alloc_check(union bpf_attr *attr)
{
        bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
        int numa_node = bpf_map_attr_numa_node(attr);

        /* check sanity of attributes */
        if (attr->max_entries == 0 || attr->key_size != 4 ||
            attr->value_size == 0 ||
            attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
            !bpf_map_flags_access_ok(attr->map_flags) ||
            (percpu && numa_node != NUMA_NO_NODE))
                return -EINVAL;

        if (attr->map_type != BPF_MAP_TYPE_ARRAY &&
            attr->map_flags & BPF_F_MMAPABLE)
                return -EINVAL;

        if (attr->value_size > KMALLOC_MAX_SIZE)
                /* if value_size is bigger, the user space won't be able to
                 * access the elements.
                 */
                return -E2BIG;

        return 0;
}

static struct bpf_map *array_map_alloc(union bpf_attr *attr)
{
        bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
        int ret, numa_node = bpf_map_attr_numa_node(attr);
        u32 elem_size, index_mask, max_entries;
        bool unpriv = !capable(CAP_SYS_ADMIN);
        u64 cost, array_size, mask64;
        struct bpf_map_memory mem;
        struct bpf_array *array;

        elem_size = round_up(attr->value_size, 8);

        max_entries = attr->max_entries;

        /* On 32 bit archs roundup_pow_of_two() with max_entries that has
         * upper most bit set in u32 space is undefined behavior due to
         * resulting 1U << 32, so do it manually here in u64 space.
         */
        mask64 = fls_long(max_entries - 1);
        mask64 = 1ULL << mask64;
        mask64 -= 1;

        index_mask = mask64;
        if (unpriv) {
                /* round up array size to nearest power of 2,
                 * since cpu will speculate within index_mask limits
                 */
                max_entries = index_mask + 1;
                /* Check for overflows. */
                if (max_entries < attr->max_entries)
                        return ERR_PTR(-E2BIG);
        }

        array_size = sizeof(*array);
        if (percpu) {
                array_size += (u64) max_entries * sizeof(void *);
        } else {
                /* rely on vmalloc() to return page-aligned memory and
                 * ensure array->value is exactly page-aligned
                 */
                if (attr->map_flags & BPF_F_MMAPABLE) {
                        array_size = PAGE_ALIGN(array_size);
                        array_size += PAGE_ALIGN((u64) max_entries * elem_size);
                } else {
                        array_size += (u64) max_entries * elem_size;
                }
        }

        /* make sure there is no u32 overflow later in round_up() */
        cost = array_size;
        if (percpu)
                cost += (u64)attr->max_entries * elem_size * num_possible_cpus();

        ret = bpf_map_charge_init(&mem, cost);
        if (ret < 0)
                return ERR_PTR(ret);

        /* allocate all map elements and zero-initialize them */
        if (attr->map_flags & BPF_F_MMAPABLE) {
                void *data;

                /* kmalloc'ed memory can't be mmap'ed, use explicit vmalloc */
                data = bpf_map_area_mmapable_alloc(array_size, numa_node);
                if (!data) {
                        bpf_map_charge_finish(&mem);
                        return ERR_PTR(-ENOMEM);
                }
                array = data + PAGE_ALIGN(sizeof(struct bpf_array))
                        - offsetof(struct bpf_array, value);
        } else {
                array = bpf_map_area_alloc(array_size, numa_node);
        }
        if (!array) {
                bpf_map_charge_finish(&mem);
                return ERR_PTR(-ENOMEM);
        }
        array->index_mask = index_mask;
        array->map.unpriv_array = unpriv;

        /* copy mandatory map attributes */
        bpf_map_init_from_attr(&array->map, attr);
        bpf_map_charge_move(&array->map.memory, &mem);
        array->elem_size = elem_size;

        if (percpu && bpf_array_alloc_percpu(array)) {
                bpf_map_charge_finish(&array->map.memory);
                bpf_map_area_free(array);
                return ERR_PTR(-ENOMEM);
        }

        return &array->map;
}

/* Called from syscall or from eBPF program */
static void *array_map_lookup_elem(struct bpf_map *map, void *key)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = *(u32 *)key;

        if (unlikely(index >= array->map.max_entries))
                return NULL;

        return array->value + array->elem_size * (index & array->index_mask);
}

static int array_map_direct_value_addr(const struct bpf_map *map, u64 *imm,
                                       u32 off)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);

        if (map->max_entries != 1)
                return -ENOTSUPP;
        if (off >= map->value_size)
                return -EINVAL;

        *imm = (unsigned long)array->value;
        return 0;
}

static int array_map_direct_value_meta(const struct bpf_map *map, u64 imm,
                                       u32 *off)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u64 base = (unsigned long)array->value;
        u64 range = array->elem_size;

        if (map->max_entries != 1)
                return -ENOTSUPP;
        if (imm < base || imm >= base + range)
                return -ENOENT;

        *off = imm - base;
        return 0;
}

/* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        struct bpf_insn *insn = insn_buf;
        u32 elem_size = round_up(map->value_size, 8);
        const int ret = BPF_REG_0;
        const int map_ptr = BPF_REG_1;
        const int index = BPF_REG_2;

        *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
        *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
        if (map->unpriv_array) {
                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4);
                *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
        } else {
                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
        }

        if (is_power_of_2(elem_size)) {
                *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
        } else {
                *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
        }
        *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
        *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
        *insn++ = BPF_MOV64_IMM(ret, 0);
        return insn - insn_buf;
}

/* Called from eBPF program */
static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = *(u32 *)key;

        if (unlikely(index >= array->map.max_entries))
                return NULL;

        return this_cpu_ptr(array->pptrs[index & array->index_mask]);
}

int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = *(u32 *)key;
        void __percpu *pptr;
        int cpu, off = 0;
        u32 size;

        if (unlikely(index >= array->map.max_entries))
                return -ENOENT;

        /* per_cpu areas are zero-filled and bpf programs can only
         * access 'value_size' of them, so copying rounded areas
         * will not leak any kernel data
         */
        size = round_up(map->value_size, 8);
        rcu_read_lock();
        pptr = array->pptrs[index & array->index_mask];
        for_each_possible_cpu(cpu) {
                bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
                off += size;
        }
        rcu_read_unlock();
        return 0;
}

/* Called from syscall */
static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = key ? *(u32 *)key : U32_MAX;
        u32 *next = (u32 *)next_key;

        if (index >= array->map.max_entries) {
                *next = 0;
                return 0;
        }

        if (index == array->map.max_entries - 1)
                return -ENOENT;

        *next = index + 1;
        return 0;
}

/* Called from syscall or from eBPF program */
static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
                                 u64 map_flags)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = *(u32 *)key;
        char *val;

        if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
                /* unknown flags */
                return -EINVAL;

        if (unlikely(index >= array->map.max_entries))
                /* all elements were pre-allocated, cannot insert a new one */
                return -E2BIG;

        if (unlikely(map_flags & BPF_NOEXIST))
                /* all elements already exist */
                return -EEXIST;

        if (unlikely((map_flags & BPF_F_LOCK) &&
                     !map_value_has_spin_lock(map)))
                return -EINVAL;

        if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
                memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
                       value, map->value_size);
        } else {
                val = array->value +
                        array->elem_size * (index & array->index_mask);
                if (map_flags & BPF_F_LOCK)
                        copy_map_value_locked(map, val, value, false);
                else
                        copy_map_value(map, val, value);
        }
        return 0;
}

int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
                            u64 map_flags)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = *(u32 *)key;
        void __percpu *pptr;
        int cpu, off = 0;
        u32 size;

        if (unlikely(map_flags > BPF_EXIST))
                /* unknown flags */
                return -EINVAL;

        if (unlikely(index >= array->map.max_entries))
                /* all elements were pre-allocated, cannot insert a new one */
                return -E2BIG;

        if (unlikely(map_flags == BPF_NOEXIST))
                /* all elements already exist */
                return -EEXIST;

        /* the user space will provide round_up(value_size, 8) bytes that
         * will be copied into per-cpu area. bpf programs can only access
         * value_size of it. During lookup the same extra bytes will be
         * returned or zeros which were zero-filled by percpu_alloc,
         * so no kernel data leaks possible
         */
        size = round_up(map->value_size, 8);
        rcu_read_lock();
        pptr = array->pptrs[index & array->index_mask];
        for_each_possible_cpu(cpu) {
                bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
                off += size;
        }
        rcu_read_unlock();
        return 0;
}

/* Called from syscall or from eBPF program */
static int array_map_delete_elem(struct bpf_map *map, void *key)
{
        return -EINVAL;
}

static void *array_map_vmalloc_addr(struct bpf_array *array)
{
        return (void *)round_down((unsigned long)array, PAGE_SIZE);
}

/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void array_map_free(struct bpf_map *map)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);

        /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
         * so the programs (can be more than one that used this map) were
         * disconnected from events. Wait for outstanding programs to complete
         * and free the array
         */
        synchronize_rcu();

        if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
                bpf_array_free_percpu(array);

        if (array->map.map_flags & BPF_F_MMAPABLE)
                bpf_map_area_free(array_map_vmalloc_addr(array));
        else
                bpf_map_area_free(array);
}

static void array_map_seq_show_elem(struct bpf_map *map, void *key,
                                    struct seq_file *m)
{
        void *value;

        rcu_read_lock();

        value = array_map_lookup_elem(map, key);
        if (!value) {
                rcu_read_unlock();
                return;
        }

        if (map->btf_key_type_id)
                seq_printf(m, "%u: ", *(u32 *)key);
        btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
        seq_puts(m, "\n");

        rcu_read_unlock();
}

static void percpu_array_map_seq_show_elem(struct bpf_map *map, void *key,
                                           struct seq_file *m)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 index = *(u32 *)key;
        void __percpu *pptr;
        int cpu;

        rcu_read_lock();

        seq_printf(m, "%u: {\n", *(u32 *)key);
        pptr = array->pptrs[index & array->index_mask];
        for_each_possible_cpu(cpu) {
                seq_printf(m, "\tcpu%d: ", cpu);
                btf_type_seq_show(map->btf, map->btf_value_type_id,
                                  per_cpu_ptr(pptr, cpu), m);
                seq_puts(m, "\n");
        }
        seq_puts(m, "}\n");

        rcu_read_unlock();
}

static int array_map_check_btf(const struct bpf_map *map,
                               const struct btf *btf,
                               const struct btf_type *key_type,
                               const struct btf_type *value_type)
{
        u32 int_data;

        /* One exception for keyless BTF: .bss/.data/.rodata map */
        if (btf_type_is_void(key_type)) {
                if (map->map_type != BPF_MAP_TYPE_ARRAY ||
                    map->max_entries != 1)
                        return -EINVAL;

                if (BTF_INFO_KIND(value_type->info) != BTF_KIND_DATASEC)
                        return -EINVAL;

                return 0;
        }

        if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
                return -EINVAL;

        int_data = *(u32 *)(key_type + 1);
        /* bpf array can only take a u32 key. This check makes sure
         * that the btf matches the attr used during map_create.
         */
        if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
                return -EINVAL;

        return 0;
}

static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        pgoff_t pgoff = PAGE_ALIGN(sizeof(*array)) >> PAGE_SHIFT;

        if (!(map->map_flags & BPF_F_MMAPABLE))
                return -EINVAL;

        return remap_vmalloc_range(vma, array_map_vmalloc_addr(array), pgoff);
}

const struct bpf_map_ops array_map_ops = {
        .map_alloc_check = array_map_alloc_check,
        .map_alloc = array_map_alloc,
        .map_free = array_map_free,
        .map_get_next_key = array_map_get_next_key,
        .map_lookup_elem = array_map_lookup_elem,
        .map_update_elem = array_map_update_elem,
        .map_delete_elem = array_map_delete_elem,
        .map_gen_lookup = array_map_gen_lookup,
        .map_direct_value_addr = array_map_direct_value_addr,
        .map_direct_value_meta = array_map_direct_value_meta,
        .map_mmap = array_map_mmap,
        .map_seq_show_elem = array_map_seq_show_elem,
        .map_check_btf = array_map_check_btf,
        .map_lookup_batch = generic_map_lookup_batch,
        .map_update_batch = generic_map_update_batch,
};

const struct bpf_map_ops percpu_array_map_ops = {
        .map_alloc_check = array_map_alloc_check,
        .map_alloc = array_map_alloc,
        .map_free = array_map_free,
        .map_get_next_key = array_map_get_next_key,
        .map_lookup_elem = percpu_array_map_lookup_elem,
        .map_update_elem = array_map_update_elem,
        .map_delete_elem = array_map_delete_elem,
        .map_seq_show_elem = percpu_array_map_seq_show_elem,
        .map_check_btf = array_map_check_btf,
};

static int fd_array_map_alloc_check(union bpf_attr *attr)
{
        /* only file descriptors can be stored in this type of map */
        if (attr->value_size != sizeof(u32))
                return -EINVAL;
        /* Program read-only/write-only not supported for special maps yet. */
        if (attr->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG))
                return -EINVAL;
        return array_map_alloc_check(attr);
}

static void fd_array_map_free(struct bpf_map *map)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        int i;

        synchronize_rcu();

        /* make sure it's empty */
        for (i = 0; i < array->map.max_entries; i++)
                BUG_ON(array->ptrs[i] != NULL);

        bpf_map_area_free(array);
}

static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
{
        return ERR_PTR(-EOPNOTSUPP);
}

/* only called from syscall */
int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
{
        void **elem, *ptr;
        int ret =  0;

        if (!map->ops->map_fd_sys_lookup_elem)
                return -ENOTSUPP;

        rcu_read_lock();
        elem = array_map_lookup_elem(map, key);
        if (elem && (ptr = READ_ONCE(*elem)))
                *value = map->ops->map_fd_sys_lookup_elem(ptr);
        else
                ret = -ENOENT;
        rcu_read_unlock();

        return ret;
}

/* only called from syscall */
int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
                                 void *key, void *value, u64 map_flags)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        void *new_ptr, *old_ptr;
        u32 index = *(u32 *)key, ufd;

        if (map_flags != BPF_ANY)
                return -EINVAL;

        if (index >= array->map.max_entries)
                return -E2BIG;

        ufd = *(u32 *)value;
        new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
        if (IS_ERR(new_ptr))
                return PTR_ERR(new_ptr);

        if (map->ops->map_poke_run) {
                mutex_lock(&array->aux->poke_mutex);
                old_ptr = xchg(array->ptrs + index, new_ptr);
                map->ops->map_poke_run(map, index, old_ptr, new_ptr);
                mutex_unlock(&array->aux->poke_mutex);
        } else {
                old_ptr = xchg(array->ptrs + index, new_ptr);
        }

        if (old_ptr)
                map->ops->map_fd_put_ptr(old_ptr);
        return 0;
}

static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        void *old_ptr;
        u32 index = *(u32 *)key;

        if (index >= array->map.max_entries)
                return -E2BIG;

        if (map->ops->map_poke_run) {
                mutex_lock(&array->aux->poke_mutex);
                old_ptr = xchg(array->ptrs + index, NULL);
                map->ops->map_poke_run(map, index, old_ptr, NULL);
                mutex_unlock(&array->aux->poke_mutex);
        } else {
                old_ptr = xchg(array->ptrs + index, NULL);
        }

        if (old_ptr) {
                map->ops->map_fd_put_ptr(old_ptr);
                return 0;
        } else {
                return -ENOENT;
        }
}

static void *prog_fd_array_get_ptr(struct bpf_map *map,
                                   struct file *map_file, int fd)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        struct bpf_prog *prog = bpf_prog_get(fd);

        if (IS_ERR(prog))
                return prog;

        if (!bpf_prog_array_compatible(array, prog)) {
                bpf_prog_put(prog);
                return ERR_PTR(-EINVAL);
        }

        return prog;
}

static void prog_fd_array_put_ptr(void *ptr)
{
        bpf_prog_put(ptr);
}

static u32 prog_fd_array_sys_lookup_elem(void *ptr)
{
        return ((struct bpf_prog *)ptr)->aux->id;
}

/* decrement refcnt of all bpf_progs that are stored in this map */
static void bpf_fd_array_map_clear(struct bpf_map *map)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        int i;

        for (i = 0; i < array->map.max_entries; i++)
                fd_array_map_delete_elem(map, &i);
}

static void prog_array_map_seq_show_elem(struct bpf_map *map, void *key,
                                         struct seq_file *m)
{
        void **elem, *ptr;
        u32 prog_id;

        rcu_read_lock();

        elem = array_map_lookup_elem(map, key);
        if (elem) {
                ptr = READ_ONCE(*elem);
                if (ptr) {
                        seq_printf(m, "%u: ", *(u32 *)key);
                        prog_id = prog_fd_array_sys_lookup_elem(ptr);
                        btf_type_seq_show(map->btf, map->btf_value_type_id,
                                          &prog_id, m);
                        seq_puts(m, "\n");
                }
        }

        rcu_read_unlock();
}

struct prog_poke_elem {
        struct list_head list;
        struct bpf_prog_aux *aux;
};

static int prog_array_map_poke_track(struct bpf_map *map,
                                     struct bpf_prog_aux *prog_aux)
{
        struct prog_poke_elem *elem;
        struct bpf_array_aux *aux;
        int ret = 0;

        aux = container_of(map, struct bpf_array, map)->aux;
        mutex_lock(&aux->poke_mutex);
        list_for_each_entry(elem, &aux->poke_progs, list) {
                if (elem->aux == prog_aux)
                        goto out;
        }

        elem = kmalloc(sizeof(*elem), GFP_KERNEL);
        if (!elem) {
                ret = -ENOMEM;
                goto out;
        }

        INIT_LIST_HEAD(&elem->list);
        /* We must track the program's aux info at this point in time
         * since the program pointer itself may not be stable yet, see
         * also comment in prog_array_map_poke_run().
         */
        elem->aux = prog_aux;

        list_add_tail(&elem->list, &aux->poke_progs);
out:
        mutex_unlock(&aux->poke_mutex);
        return ret;
}

static void prog_array_map_poke_untrack(struct bpf_map *map,
                                        struct bpf_prog_aux *prog_aux)
{
        struct prog_poke_elem *elem, *tmp;
        struct bpf_array_aux *aux;

        aux = container_of(map, struct bpf_array, map)->aux;
        mutex_lock(&aux->poke_mutex);
        list_for_each_entry_safe(elem, tmp, &aux->poke_progs, list) {
                if (elem->aux == prog_aux) {
                        list_del_init(&elem->list);
                        kfree(elem);
                        break;
                }
        }
        mutex_unlock(&aux->poke_mutex);
}

static void prog_array_map_poke_run(struct bpf_map *map, u32 key,
                                    struct bpf_prog *old,
                                    struct bpf_prog *new)
{
        struct prog_poke_elem *elem;
        struct bpf_array_aux *aux;

        aux = container_of(map, struct bpf_array, map)->aux;
        WARN_ON_ONCE(!mutex_is_locked(&aux->poke_mutex));

        list_for_each_entry(elem, &aux->poke_progs, list) {
                struct bpf_jit_poke_descriptor *poke;
                int i, ret;

                for (i = 0; i < elem->aux->size_poke_tab; i++) {
                        poke = &elem->aux->poke_tab[i];

                        /* Few things to be aware of:
                         *
                         * 1) We can only ever access aux in this context, but
                         *    not aux->prog since it might not be stable yet and
                         *    there could be danger of use after free otherwise.
                         * 2) Initially when we start tracking aux, the program
                         *    is not JITed yet and also does not have a kallsyms
                         *    entry. We skip these as poke->ip_stable is not
                         *    active yet. The JIT will do the final fixup before
                         *    setting it stable. The various poke->ip_stable are
                         *    successively activated, so tail call updates can
                         *    arrive from here while JIT is still finishing its
                         *    final fixup for non-activated poke entries.
                         * 3) On program teardown, the program's kallsym entry gets
                         *    removed out of RCU callback, but we can only untrack
                         *    from sleepable context, therefore bpf_arch_text_poke()
                         *    might not see that this is in BPF text section and
                         *    bails out with -EINVAL. As these are unreachable since
                         *    RCU grace period already passed, we simply skip them.
                         * 4) Also programs reaching refcount of zero while patching
                         *    is in progress is okay since we're protected under
                         *    poke_mutex and untrack the programs before the JIT
                         *    buffer is freed. When we're still in the middle of
                         *    patching and suddenly kallsyms entry of the program
                         *    gets evicted, we just skip the rest which is fine due
                         *    to point 3).
                         * 5) Any other error happening below from bpf_arch_text_poke()
                         *    is a unexpected bug.
                         */
                        if (!READ_ONCE(poke->ip_stable))
                                continue;
                        if (poke->reason != BPF_POKE_REASON_TAIL_CALL)
                                continue;
                        if (poke->tail_call.map != map ||
                            poke->tail_call.key != key)
                                continue;

                        ret = bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP,
                                                 old ? (u8 *)old->bpf_func +
                                                 poke->adj_off : NULL,
                                                 new ? (u8 *)new->bpf_func +
                                                 poke->adj_off : NULL);
                        BUG_ON(ret < 0 && ret != -EINVAL);
                }
        }
}

static void prog_array_map_clear_deferred(struct work_struct *work)
{
        struct bpf_map *map = container_of(work, struct bpf_array_aux,
                                           work)->map;
        bpf_fd_array_map_clear(map);
        bpf_map_put(map);
}

static void prog_array_map_clear(struct bpf_map *map)
{
        struct bpf_array_aux *aux = container_of(map, struct bpf_array,
                                                 map)->aux;
        bpf_map_inc(map);
        schedule_work(&aux->work);
}

static struct bpf_map *prog_array_map_alloc(union bpf_attr *attr)
{
        struct bpf_array_aux *aux;
        struct bpf_map *map;

        aux = kzalloc(sizeof(*aux), GFP_KERNEL);
        if (!aux)
                return ERR_PTR(-ENOMEM);

        INIT_WORK(&aux->work, prog_array_map_clear_deferred);
        INIT_LIST_HEAD(&aux->poke_progs);
        mutex_init(&aux->poke_mutex);

        map = array_map_alloc(attr);
        if (IS_ERR(map)) {
                kfree(aux);
                return map;
        }

        container_of(map, struct bpf_array, map)->aux = aux;
        aux->map = map;

        return map;
}

static void prog_array_map_free(struct bpf_map *map)
{
        struct prog_poke_elem *elem, *tmp;
        struct bpf_array_aux *aux;

        aux = container_of(map, struct bpf_array, map)->aux;
        list_for_each_entry_safe(elem, tmp, &aux->poke_progs, list) {
                list_del_init(&elem->list);
                kfree(elem);
        }
        kfree(aux);
        fd_array_map_free(map);
}

const struct bpf_map_ops prog_array_map_ops = {
        .map_alloc_check = fd_array_map_alloc_check,
        .map_alloc = prog_array_map_alloc,
        .map_free = prog_array_map_free,
        .map_poke_track = prog_array_map_poke_track,
        .map_poke_untrack = prog_array_map_poke_untrack,
        .map_poke_run = prog_array_map_poke_run,
        .map_get_next_key = array_map_get_next_key,
        .map_lookup_elem = fd_array_map_lookup_elem,
        .map_delete_elem = fd_array_map_delete_elem,
        .map_fd_get_ptr = prog_fd_array_get_ptr,
        .map_fd_put_ptr = prog_fd_array_put_ptr,
        .map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,
        .map_release_uref = prog_array_map_clear,
        .map_seq_show_elem = prog_array_map_seq_show_elem,
};

static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
                                                   struct file *map_file)
{
        struct bpf_event_entry *ee;

        ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
        if (ee) {
                ee->event = perf_file->private_data;
                ee->perf_file = perf_file;
                ee->map_file = map_file;
        }

        return ee;
}

static void __bpf_event_entry_free(struct rcu_head *rcu)
{
        struct bpf_event_entry *ee;

        ee = container_of(rcu, struct bpf_event_entry, rcu);
        fput(ee->perf_file);
        kfree(ee);
}

static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
{
        call_rcu(&ee->rcu, __bpf_event_entry_free);
}

static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
                                         struct file *map_file, int fd)
{
        struct bpf_event_entry *ee;
        struct perf_event *event;
        struct file *perf_file;
        u64 value;

        perf_file = perf_event_get(fd);
        if (IS_ERR(perf_file))
                return perf_file;

        ee = ERR_PTR(-EOPNOTSUPP);
        event = perf_file->private_data;
        if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP)
                goto err_out;

        ee = bpf_event_entry_gen(perf_file, map_file);
        if (ee)
                return ee;
        ee = ERR_PTR(-ENOMEM);
err_out:
        fput(perf_file);
        return ee;
}

static void perf_event_fd_array_put_ptr(void *ptr)
{
        bpf_event_entry_free_rcu(ptr);
}

static void perf_event_fd_array_release(struct bpf_map *map,
                                        struct file *map_file)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        struct bpf_event_entry *ee;
        int i;

        rcu_read_lock();
        for (i = 0; i < array->map.max_entries; i++) {
                ee = READ_ONCE(array->ptrs[i]);
                if (ee && ee->map_file == map_file)
                        fd_array_map_delete_elem(map, &i);
        }
        rcu_read_unlock();
}

const struct bpf_map_ops perf_event_array_map_ops = {
        .map_alloc_check = fd_array_map_alloc_check,
        .map_alloc = array_map_alloc,
        .map_free = fd_array_map_free,
        .map_get_next_key = array_map_get_next_key,
        .map_lookup_elem = fd_array_map_lookup_elem,
        .map_delete_elem = fd_array_map_delete_elem,
        .map_fd_get_ptr = perf_event_fd_array_get_ptr,
        .map_fd_put_ptr = perf_event_fd_array_put_ptr,
        .map_release = perf_event_fd_array_release,
        .map_check_btf = map_check_no_btf,
};

#ifdef CONFIG_CGROUPS
static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
                                     struct file *map_file /* not used */,
                                     int fd)
{
        return cgroup_get_from_fd(fd);
}

static void cgroup_fd_array_put_ptr(void *ptr)
{
        /* cgroup_put free cgrp after a rcu grace period */
        cgroup_put(ptr);
}

static void cgroup_fd_array_free(struct bpf_map *map)
{
        bpf_fd_array_map_clear(map);
        fd_array_map_free(map);
}

const struct bpf_map_ops cgroup_array_map_ops = {
        .map_alloc_check = fd_array_map_alloc_check,
        .map_alloc = array_map_alloc,
        .map_free = cgroup_fd_array_free,
        .map_get_next_key = array_map_get_next_key,
        .map_lookup_elem = fd_array_map_lookup_elem,
        .map_delete_elem = fd_array_map_delete_elem,
        .map_fd_get_ptr = cgroup_fd_array_get_ptr,
        .map_fd_put_ptr = cgroup_fd_array_put_ptr,
        .map_check_btf = map_check_no_btf,
};
#endif

static struct bpf_map *array_of_map_alloc(union bpf_attr *attr)
{
        struct bpf_map *map, *inner_map_meta;

        inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
        if (IS_ERR(inner_map_meta))
                return inner_map_meta;

        map = array_map_alloc(attr);
        if (IS_ERR(map)) {
                bpf_map_meta_free(inner_map_meta);
                return map;
        }

        map->inner_map_meta = inner_map_meta;

        return map;
}

static void array_of_map_free(struct bpf_map *map)
{
        /* map->inner_map_meta is only accessed by syscall which
         * is protected by fdget/fdput.
         */
        bpf_map_meta_free(map->inner_map_meta);
        bpf_fd_array_map_clear(map);
        fd_array_map_free(map);
}

static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
{
        struct bpf_map **inner_map = array_map_lookup_elem(map, key);

        if (!inner_map)
                return NULL;

        return READ_ONCE(*inner_map);
}

static u32 array_of_map_gen_lookup(struct bpf_map *map,
                                   struct bpf_insn *insn_buf)
{
        struct bpf_array *array = container_of(map, struct bpf_array, map);
        u32 elem_size = round_up(map->value_size, 8);
        struct bpf_insn *insn = insn_buf;
        const int ret = BPF_REG_0;
        const int map_ptr = BPF_REG_1;
        const int index = BPF_REG_2;

        *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
        *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
        if (map->unpriv_array) {
                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
                *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
        } else {
                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
        }
        if (is_power_of_2(elem_size))
                *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
        else
                *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
        *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
        *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
        *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
        *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
        *insn++ = BPF_MOV64_IMM(ret, 0);

        return insn - insn_buf;
}

const struct bpf_map_ops array_of_maps_map_ops = {
        .map_alloc_check = fd_array_map_alloc_check,
        .map_alloc = array_of_map_alloc,
        .map_free = array_of_map_free,
        .map_get_next_key = array_map_get_next_key,
        .map_lookup_elem = array_of_map_lookup_elem,
        .map_delete_elem = fd_array_map_delete_elem,
        .map_fd_get_ptr = bpf_map_fd_get_ptr,
        .map_fd_put_ptr = bpf_map_fd_put_ptr,
        .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
        .map_gen_lookup = array_of_map_gen_lookup,
        .map_check_btf = map_check_no_btf,
};