vt: perform safe console erase in the right order

[linux.git] / kernel / bpf / core.c

/*
 * Linux Socket Filter - Kernel level socket filtering
 *
 * Based on the design of the Berkeley Packet Filter. The new
 * internal format has been designed by PLUMgrid:
 *
 *      Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
 *
 * Authors:
 *
 *      Jay Schulist <[email protected]>
 *      Alexei Starovoitov <[email protected]>
 *      Daniel Borkmann <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * Andi Kleen - Fix a few bad bugs and races.
 * Kris Katterjohn - Added many additional checks in bpf_check_classic()
 */

#include <uapi/linux/btf.h>
#include <linux/filter.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <linux/random.h>
#include <linux/moduleloader.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/frame.h>
#include <linux/rbtree_latch.h>
#include <linux/kallsyms.h>
#include <linux/rcupdate.h>
#include <linux/perf_event.h>

#include <asm/unaligned.h>

/* Registers */
#define BPF_R0  regs[BPF_REG_0]
#define BPF_R1  regs[BPF_REG_1]
#define BPF_R2  regs[BPF_REG_2]
#define BPF_R3  regs[BPF_REG_3]
#define BPF_R4  regs[BPF_REG_4]
#define BPF_R5  regs[BPF_REG_5]
#define BPF_R6  regs[BPF_REG_6]
#define BPF_R7  regs[BPF_REG_7]
#define BPF_R8  regs[BPF_REG_8]
#define BPF_R9  regs[BPF_REG_9]
#define BPF_R10 regs[BPF_REG_10]

/* Named registers */
#define DST     regs[insn->dst_reg]
#define SRC     regs[insn->src_reg]
#define FP      regs[BPF_REG_FP]
#define AX      regs[BPF_REG_AX]
#define ARG1    regs[BPF_REG_ARG1]
#define CTX     regs[BPF_REG_CTX]
#define IMM     insn->imm

/* No hurry in this branch
 *
 * Exported for the bpf jit load helper.
 */
void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
{
        u8 *ptr = NULL;

        if (k >= SKF_NET_OFF)
                ptr = skb_network_header(skb) + k - SKF_NET_OFF;
        else if (k >= SKF_LL_OFF)
                ptr = skb_mac_header(skb) + k - SKF_LL_OFF;

        if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
                return ptr;

        return NULL;
}

struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
{
        gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
        struct bpf_prog_aux *aux;
        struct bpf_prog *fp;

        size = round_up(size, PAGE_SIZE);
        fp = __vmalloc(size, gfp_flags, PAGE_KERNEL);
        if (fp == NULL)
                return NULL;

        aux = kzalloc(sizeof(*aux), GFP_KERNEL | gfp_extra_flags);
        if (aux == NULL) {
                vfree(fp);
                return NULL;
        }

        fp->pages = size / PAGE_SIZE;
        fp->aux = aux;
        fp->aux->prog = fp;
        fp->jit_requested = ebpf_jit_enabled();

        INIT_LIST_HEAD_RCU(&fp->aux->ksym_lnode);

        return fp;
}
EXPORT_SYMBOL_GPL(bpf_prog_alloc);

int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog)
{
        if (!prog->aux->nr_linfo || !prog->jit_requested)
                return 0;

        prog->aux->jited_linfo = kcalloc(prog->aux->nr_linfo,
                                         sizeof(*prog->aux->jited_linfo),
                                         GFP_KERNEL | __GFP_NOWARN);
        if (!prog->aux->jited_linfo)
                return -ENOMEM;

        return 0;
}

void bpf_prog_free_jited_linfo(struct bpf_prog *prog)
{
        kfree(prog->aux->jited_linfo);
        prog->aux->jited_linfo = NULL;
}

void bpf_prog_free_unused_jited_linfo(struct bpf_prog *prog)
{
        if (prog->aux->jited_linfo && !prog->aux->jited_linfo[0])
                bpf_prog_free_jited_linfo(prog);
}

/* The jit engine is responsible to provide an array
 * for insn_off to the jited_off mapping (insn_to_jit_off).
 *
 * The idx to this array is the insn_off.  Hence, the insn_off
 * here is relative to the prog itself instead of the main prog.
 * This array has one entry for each xlated bpf insn.
 *
 * jited_off is the byte off to the last byte of the jited insn.
 *
 * Hence, with
 * insn_start:
 *      The first bpf insn off of the prog.  The insn off
 *      here is relative to the main prog.
 *      e.g. if prog is a subprog, insn_start > 0
 * linfo_idx:
 *      The prog's idx to prog->aux->linfo and jited_linfo
 *
 * jited_linfo[linfo_idx] = prog->bpf_func
 *
 * For i > linfo_idx,
 *
 * jited_linfo[i] = prog->bpf_func +
 *      insn_to_jit_off[linfo[i].insn_off - insn_start - 1]
 */
void bpf_prog_fill_jited_linfo(struct bpf_prog *prog,
                               const u32 *insn_to_jit_off)
{
        u32 linfo_idx, insn_start, insn_end, nr_linfo, i;
        const struct bpf_line_info *linfo;
        void **jited_linfo;

        if (!prog->aux->jited_linfo)
                /* Userspace did not provide linfo */
                return;

        linfo_idx = prog->aux->linfo_idx;
        linfo = &prog->aux->linfo[linfo_idx];
        insn_start = linfo[0].insn_off;
        insn_end = insn_start + prog->len;

        jited_linfo = &prog->aux->jited_linfo[linfo_idx];
        jited_linfo[0] = prog->bpf_func;

        nr_linfo = prog->aux->nr_linfo - linfo_idx;

        for (i = 1; i < nr_linfo && linfo[i].insn_off < insn_end; i++)
                /* The verifier ensures that linfo[i].insn_off is
                 * strictly increasing
                 */
                jited_linfo[i] = prog->bpf_func +
                        insn_to_jit_off[linfo[i].insn_off - insn_start - 1];
}

void bpf_prog_free_linfo(struct bpf_prog *prog)
{
        bpf_prog_free_jited_linfo(prog);
        kvfree(prog->aux->linfo);
}

struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
                                  gfp_t gfp_extra_flags)
{
        gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
        struct bpf_prog *fp;
        u32 pages, delta;
        int ret;

        BUG_ON(fp_old == NULL);

        size = round_up(size, PAGE_SIZE);
        pages = size / PAGE_SIZE;
        if (pages <= fp_old->pages)
                return fp_old;

        delta = pages - fp_old->pages;
        ret = __bpf_prog_charge(fp_old->aux->user, delta);
        if (ret)
                return NULL;

        fp = __vmalloc(size, gfp_flags, PAGE_KERNEL);
        if (fp == NULL) {
                __bpf_prog_uncharge(fp_old->aux->user, delta);
        } else {
                memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE);
                fp->pages = pages;
                fp->aux->prog = fp;

                /* We keep fp->aux from fp_old around in the new
                 * reallocated structure.
                 */
                fp_old->aux = NULL;
                __bpf_prog_free(fp_old);
        }

        return fp;
}

void __bpf_prog_free(struct bpf_prog *fp)
{
        kfree(fp->aux);
        vfree(fp);
}

int bpf_prog_calc_tag(struct bpf_prog *fp)
{
        const u32 bits_offset = SHA_MESSAGE_BYTES - sizeof(__be64);
        u32 raw_size = bpf_prog_tag_scratch_size(fp);
        u32 digest[SHA_DIGEST_WORDS];
        u32 ws[SHA_WORKSPACE_WORDS];
        u32 i, bsize, psize, blocks;
        struct bpf_insn *dst;
        bool was_ld_map;
        u8 *raw, *todo;
        __be32 *result;
        __be64 *bits;

        raw = vmalloc(raw_size);
        if (!raw)
                return -ENOMEM;

        sha_init(digest);
        memset(ws, 0, sizeof(ws));

        /* We need to take out the map fd for the digest calculation
         * since they are unstable from user space side.
         */
        dst = (void *)raw;
        for (i = 0, was_ld_map = false; i < fp->len; i++) {
                dst[i] = fp->insnsi[i];
                if (!was_ld_map &&
                    dst[i].code == (BPF_LD | BPF_IMM | BPF_DW) &&
                    dst[i].src_reg == BPF_PSEUDO_MAP_FD) {
                        was_ld_map = true;
                        dst[i].imm = 0;
                } else if (was_ld_map &&
                           dst[i].code == 0 &&
                           dst[i].dst_reg == 0 &&
                           dst[i].src_reg == 0 &&
                           dst[i].off == 0) {
                        was_ld_map = false;
                        dst[i].imm = 0;
                } else {
                        was_ld_map = false;
                }
        }

        psize = bpf_prog_insn_size(fp);
        memset(&raw[psize], 0, raw_size - psize);
        raw[psize++] = 0x80;

        bsize  = round_up(psize, SHA_MESSAGE_BYTES);
        blocks = bsize / SHA_MESSAGE_BYTES;
        todo   = raw;
        if (bsize - psize >= sizeof(__be64)) {
                bits = (__be64 *)(todo + bsize - sizeof(__be64));
        } else {
                bits = (__be64 *)(todo + bsize + bits_offset);
                blocks++;
        }
        *bits = cpu_to_be64((psize - 1) << 3);

        while (blocks--) {
                sha_transform(digest, todo, ws);
                todo += SHA_MESSAGE_BYTES;
        }

        result = (__force __be32 *)digest;
        for (i = 0; i < SHA_DIGEST_WORDS; i++)
                result[i] = cpu_to_be32(digest[i]);
        memcpy(fp->tag, result, sizeof(fp->tag));

        vfree(raw);
        return 0;
}

static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, u32 delta,
                                u32 curr, const bool probe_pass)
{
        const s64 imm_min = S32_MIN, imm_max = S32_MAX;
        s64 imm = insn->imm;

        if (curr < pos && curr + imm + 1 > pos)
                imm += delta;
        else if (curr > pos + delta && curr + imm + 1 <= pos + delta)
                imm -= delta;
        if (imm < imm_min || imm > imm_max)
                return -ERANGE;
        if (!probe_pass)
                insn->imm = imm;
        return 0;
}

static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, u32 delta,
                                u32 curr, const bool probe_pass)
{
        const s32 off_min = S16_MIN, off_max = S16_MAX;
        s32 off = insn->off;

        if (curr < pos && curr + off + 1 > pos)
                off += delta;
        else if (curr > pos + delta && curr + off + 1 <= pos + delta)
                off -= delta;
        if (off < off_min || off > off_max)
                return -ERANGE;
        if (!probe_pass)
                insn->off = off;
        return 0;
}

static int bpf_adj_branches(struct bpf_prog *prog, u32 pos, u32 delta,
                            const bool probe_pass)
{
        u32 i, insn_cnt = prog->len + (probe_pass ? delta : 0);
        struct bpf_insn *insn = prog->insnsi;
        int ret = 0;

        for (i = 0; i < insn_cnt; i++, insn++) {
                u8 code;

                /* In the probing pass we still operate on the original,
                 * unpatched image in order to check overflows before we
                 * do any other adjustments. Therefore skip the patchlet.
                 */
                if (probe_pass && i == pos) {
                        i += delta + 1;
                        insn++;
                }
                code = insn->code;
                if (BPF_CLASS(code) != BPF_JMP ||
                    BPF_OP(code) == BPF_EXIT)
                        continue;
                /* Adjust offset of jmps if we cross patch boundaries. */
                if (BPF_OP(code) == BPF_CALL) {
                        if (insn->src_reg != BPF_PSEUDO_CALL)
                                continue;
                        ret = bpf_adj_delta_to_imm(insn, pos, delta, i,
                                                   probe_pass);
                } else {
                        ret = bpf_adj_delta_to_off(insn, pos, delta, i,
                                                   probe_pass);
                }
                if (ret)
                        break;
        }

        return ret;
}

static void bpf_adj_linfo(struct bpf_prog *prog, u32 off, u32 delta)
{
        struct bpf_line_info *linfo;
        u32 i, nr_linfo;

        nr_linfo = prog->aux->nr_linfo;
        if (!nr_linfo || !delta)
                return;

        linfo = prog->aux->linfo;

        for (i = 0; i < nr_linfo; i++)
                if (off < linfo[i].insn_off)
                        break;

        /* Push all off < linfo[i].insn_off by delta */
        for (; i < nr_linfo; i++)
                linfo[i].insn_off += delta;
}

struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
                                       const struct bpf_insn *patch, u32 len)
{
        u32 insn_adj_cnt, insn_rest, insn_delta = len - 1;
        const u32 cnt_max = S16_MAX;
        struct bpf_prog *prog_adj;

        /* Since our patchlet doesn't expand the image, we're done. */
        if (insn_delta == 0) {
                memcpy(prog->insnsi + off, patch, sizeof(*patch));
                return prog;
        }

        insn_adj_cnt = prog->len + insn_delta;

        /* Reject anything that would potentially let the insn->off
         * target overflow when we have excessive program expansions.
         * We need to probe here before we do any reallocation where
         * we afterwards may not fail anymore.
         */
        if (insn_adj_cnt > cnt_max &&
            bpf_adj_branches(prog, off, insn_delta, true))
                return NULL;

        /* Several new instructions need to be inserted. Make room
         * for them. Likely, there's no need for a new allocation as
         * last page could have large enough tailroom.
         */
        prog_adj = bpf_prog_realloc(prog, bpf_prog_size(insn_adj_cnt),
                                    GFP_USER);
        if (!prog_adj)
                return NULL;

        prog_adj->len = insn_adj_cnt;

        /* Patching happens in 3 steps:
         *
         * 1) Move over tail of insnsi from next instruction onwards,
         *    so we can patch the single target insn with one or more
         *    new ones (patching is always from 1 to n insns, n > 0).
         * 2) Inject new instructions at the target location.
         * 3) Adjust branch offsets if necessary.
         */
        insn_rest = insn_adj_cnt - off - len;

        memmove(prog_adj->insnsi + off + len, prog_adj->insnsi + off + 1,
                sizeof(*patch) * insn_rest);
        memcpy(prog_adj->insnsi + off, patch, sizeof(*patch) * len);

        /* We are guaranteed to not fail at this point, otherwise
         * the ship has sailed to reverse to the original state. An
         * overflow cannot happen at this point.
         */
        BUG_ON(bpf_adj_branches(prog_adj, off, insn_delta, false));

        bpf_adj_linfo(prog_adj, off, insn_delta);

        return prog_adj;
}

void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp)
{
        int i;

        for (i = 0; i < fp->aux->func_cnt; i++)
                bpf_prog_kallsyms_del(fp->aux->func[i]);
}

void bpf_prog_kallsyms_del_all(struct bpf_prog *fp)
{
        bpf_prog_kallsyms_del_subprogs(fp);
        bpf_prog_kallsyms_del(fp);
}

#ifdef CONFIG_BPF_JIT
/* All BPF JIT sysctl knobs here. */
int bpf_jit_enable   __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_ALWAYS_ON);
int bpf_jit_harden   __read_mostly;
int bpf_jit_kallsyms __read_mostly;
long bpf_jit_limit   __read_mostly;

static __always_inline void
bpf_get_prog_addr_region(const struct bpf_prog *prog,
                         unsigned long *symbol_start,
                         unsigned long *symbol_end)
{
        const struct bpf_binary_header *hdr = bpf_jit_binary_hdr(prog);
        unsigned long addr = (unsigned long)hdr;

        WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog));

        *symbol_start = addr;
        *symbol_end   = addr + hdr->pages * PAGE_SIZE;
}

static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
{
        const char *end = sym + KSYM_NAME_LEN;
        const struct btf_type *type;
        const char *func_name;

        BUILD_BUG_ON(sizeof("bpf_prog_") +
                     sizeof(prog->tag) * 2 +
                     /* name has been null terminated.
                      * We should need +1 for the '_' preceding
                      * the name.  However, the null character
                      * is double counted between the name and the
                      * sizeof("bpf_prog_") above, so we omit
                      * the +1 here.
                      */
                     sizeof(prog->aux->name) > KSYM_NAME_LEN);

        sym += snprintf(sym, KSYM_NAME_LEN, "bpf_prog_");
        sym  = bin2hex(sym, prog->tag, sizeof(prog->tag));

        /* prog->aux->name will be ignored if full btf name is available */
        if (prog->aux->func_info_cnt) {
                type = btf_type_by_id(prog->aux->btf,
                                      prog->aux->func_info[prog->aux->func_idx].type_id);
                func_name = btf_name_by_offset(prog->aux->btf, type->name_off);
                snprintf(sym, (size_t)(end - sym), "_%s", func_name);
                return;
        }

        if (prog->aux->name[0])
                snprintf(sym, (size_t)(end - sym), "_%s", prog->aux->name);
        else
                *sym = 0;
}

static __always_inline unsigned long
bpf_get_prog_addr_start(struct latch_tree_node *n)
{
        unsigned long symbol_start, symbol_end;
        const struct bpf_prog_aux *aux;

        aux = container_of(n, struct bpf_prog_aux, ksym_tnode);
        bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end);

        return symbol_start;
}

static __always_inline bool bpf_tree_less(struct latch_tree_node *a,
                                          struct latch_tree_node *b)
{
        return bpf_get_prog_addr_start(a) < bpf_get_prog_addr_start(b);
}

static __always_inline int bpf_tree_comp(void *key, struct latch_tree_node *n)
{
        unsigned long val = (unsigned long)key;
        unsigned long symbol_start, symbol_end;
        const struct bpf_prog_aux *aux;

        aux = container_of(n, struct bpf_prog_aux, ksym_tnode);
        bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end);

        if (val < symbol_start)
                return -1;
        if (val >= symbol_end)
                return  1;

        return 0;
}

static const struct latch_tree_ops bpf_tree_ops = {
        .less   = bpf_tree_less,
        .comp   = bpf_tree_comp,
};

static DEFINE_SPINLOCK(bpf_lock);
static LIST_HEAD(bpf_kallsyms);
static struct latch_tree_root bpf_tree __cacheline_aligned;

static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux)
{
        WARN_ON_ONCE(!list_empty(&aux->ksym_lnode));
        list_add_tail_rcu(&aux->ksym_lnode, &bpf_kallsyms);
        latch_tree_insert(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops);
}

static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux)
{
        if (list_empty(&aux->ksym_lnode))
                return;

        latch_tree_erase(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops);
        list_del_rcu(&aux->ksym_lnode);
}

static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp)
{
        return fp->jited && !bpf_prog_was_classic(fp);
}

static bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp)
{
        return list_empty(&fp->aux->ksym_lnode) ||
               fp->aux->ksym_lnode.prev == LIST_POISON2;
}

void bpf_prog_kallsyms_add(struct bpf_prog *fp)
{
        if (!bpf_prog_kallsyms_candidate(fp) ||
            !capable(CAP_SYS_ADMIN))
                return;

        spin_lock_bh(&bpf_lock);
        bpf_prog_ksym_node_add(fp->aux);
        spin_unlock_bh(&bpf_lock);
}

void bpf_prog_kallsyms_del(struct bpf_prog *fp)
{
        if (!bpf_prog_kallsyms_candidate(fp))
                return;

        spin_lock_bh(&bpf_lock);
        bpf_prog_ksym_node_del(fp->aux);
        spin_unlock_bh(&bpf_lock);
}

static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr)
{
        struct latch_tree_node *n;

        if (!bpf_jit_kallsyms_enabled())
                return NULL;

        n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops);
        return n ?
               container_of(n, struct bpf_prog_aux, ksym_tnode)->prog :
               NULL;
}

const char *__bpf_address_lookup(unsigned long addr, unsigned long *size,
                                 unsigned long *off, char *sym)
{
        unsigned long symbol_start, symbol_end;
        struct bpf_prog *prog;
        char *ret = NULL;

        rcu_read_lock();
        prog = bpf_prog_kallsyms_find(addr);
        if (prog) {
                bpf_get_prog_addr_region(prog, &symbol_start, &symbol_end);
                bpf_get_prog_name(prog, sym);

                ret = sym;
                if (size)
                        *size = symbol_end - symbol_start;
                if (off)
                        *off  = addr - symbol_start;
        }
        rcu_read_unlock();

        return ret;
}

bool is_bpf_text_address(unsigned long addr)
{
        bool ret;

        rcu_read_lock();
        ret = bpf_prog_kallsyms_find(addr) != NULL;
        rcu_read_unlock();

        return ret;
}

int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
                    char *sym)
{
        struct bpf_prog_aux *aux;
        unsigned int it = 0;
        int ret = -ERANGE;

        if (!bpf_jit_kallsyms_enabled())
                return ret;

        rcu_read_lock();
        list_for_each_entry_rcu(aux, &bpf_kallsyms, ksym_lnode) {
                if (it++ != symnum)
                        continue;

                bpf_get_prog_name(aux->prog, sym);

                *value = (unsigned long)aux->prog->bpf_func;
                *type  = BPF_SYM_ELF_TYPE;

                ret = 0;
                break;
        }
        rcu_read_unlock();

        return ret;
}

static atomic_long_t bpf_jit_current;

/* Can be overridden by an arch's JIT compiler if it has a custom,
 * dedicated BPF backend memory area, or if neither of the two
 * below apply.
 */
u64 __weak bpf_jit_alloc_exec_limit(void)
{
#if defined(MODULES_VADDR)
        return MODULES_END - MODULES_VADDR;
#else
        return VMALLOC_END - VMALLOC_START;
#endif
}

static int __init bpf_jit_charge_init(void)
{
        /* Only used as heuristic here to derive limit. */
        bpf_jit_limit = min_t(u64, round_up(bpf_jit_alloc_exec_limit() >> 2,
                                            PAGE_SIZE), LONG_MAX);
        return 0;
}
pure_initcall(bpf_jit_charge_init);

static int bpf_jit_charge_modmem(u32 pages)
{
        if (atomic_long_add_return(pages, &bpf_jit_current) >
            (bpf_jit_limit >> PAGE_SHIFT)) {
                if (!capable(CAP_SYS_ADMIN)) {
                        atomic_long_sub(pages, &bpf_jit_current);
                        return -EPERM;
                }
        }

        return 0;
}

static void bpf_jit_uncharge_modmem(u32 pages)
{
        atomic_long_sub(pages, &bpf_jit_current);
}

void *__weak bpf_jit_alloc_exec(unsigned long size)
{
        return module_alloc(size);
}

void __weak bpf_jit_free_exec(void *addr)
{
        module_memfree(addr);
}

struct bpf_binary_header *
bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
                     unsigned int alignment,
                     bpf_jit_fill_hole_t bpf_fill_ill_insns)
{
        struct bpf_binary_header *hdr;
        u32 size, hole, start, pages;

        /* Most of BPF filters are really small, but if some of them
         * fill a page, allow at least 128 extra bytes to insert a
         * random section of illegal instructions.
         */
        size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);
        pages = size / PAGE_SIZE;

        if (bpf_jit_charge_modmem(pages))
                return NULL;
        hdr = bpf_jit_alloc_exec(size);
        if (!hdr) {
                bpf_jit_uncharge_modmem(pages);
                return NULL;
        }

        /* Fill space with illegal/arch-dep instructions. */
        bpf_fill_ill_insns(hdr, size);

        hdr->pages = pages;
        hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),
                     PAGE_SIZE - sizeof(*hdr));
        start = (get_random_int() % hole) & ~(alignment - 1);

        /* Leave a random number of instructions before BPF code. */
        *image_ptr = &hdr->image[start];

        return hdr;
}

void bpf_jit_binary_free(struct bpf_binary_header *hdr)
{
        u32 pages = hdr->pages;

        bpf_jit_free_exec(hdr);
        bpf_jit_uncharge_modmem(pages);
}

/* This symbol is only overridden by archs that have different
 * requirements than the usual eBPF JITs, f.e. when they only
 * implement cBPF JIT, do not set images read-only, etc.
 */
void __weak bpf_jit_free(struct bpf_prog *fp)
{
        if (fp->jited) {
                struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp);

                bpf_jit_binary_unlock_ro(hdr);
                bpf_jit_binary_free(hdr);

                WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp));
        }

        bpf_prog_unlock_free(fp);
}

int bpf_jit_get_func_addr(const struct bpf_prog *prog,
                          const struct bpf_insn *insn, bool extra_pass,
                          u64 *func_addr, bool *func_addr_fixed)
{
        s16 off = insn->off;
        s32 imm = insn->imm;
        u8 *addr;

        *func_addr_fixed = insn->src_reg != BPF_PSEUDO_CALL;
        if (!*func_addr_fixed) {
                /* Place-holder address till the last pass has collected
                 * all addresses for JITed subprograms in which case we
                 * can pick them up from prog->aux.
                 */
                if (!extra_pass)
                        addr = NULL;
                else if (prog->aux->func &&
                         off >= 0 && off < prog->aux->func_cnt)
                        addr = (u8 *)prog->aux->func[off]->bpf_func;
                else
                        return -EINVAL;
        } else {
                /* Address of a BPF helper call. Since part of the core
                 * kernel, it's always at a fixed location. __bpf_call_base
                 * and the helper with imm relative to it are both in core
                 * kernel.
                 */
                addr = (u8 *)__bpf_call_base + imm;
        }

        *func_addr = (unsigned long)addr;
        return 0;
}

static int bpf_jit_blind_insn(const struct bpf_insn *from,
                              const struct bpf_insn *aux,
                              struct bpf_insn *to_buff)
{
        struct bpf_insn *to = to_buff;
        u32 imm_rnd = get_random_int();
        s16 off;

        BUILD_BUG_ON(BPF_REG_AX  + 1 != MAX_BPF_JIT_REG);
        BUILD_BUG_ON(MAX_BPF_REG + 1 != MAX_BPF_JIT_REG);

        /* Constraints on AX register:
         *
         * AX register is inaccessible from user space. It is mapped in
         * all JITs, and used here for constant blinding rewrites. It is
         * typically "stateless" meaning its contents are only valid within
         * the executed instruction, but not across several instructions.
         * There are a few exceptions however which are further detailed
         * below.
         *
         * Constant blinding is only used by JITs, not in the interpreter.
         * The interpreter uses AX in some occasions as a local temporary
         * register e.g. in DIV or MOD instructions.
         *
         * In restricted circumstances, the verifier can also use the AX
         * register for rewrites as long as they do not interfere with
         * the above cases!
         */
        if (from->dst_reg == BPF_REG_AX || from->src_reg == BPF_REG_AX)
                goto out;

        if (from->imm == 0 &&
            (from->code == (BPF_ALU   | BPF_MOV | BPF_K) ||
             from->code == (BPF_ALU64 | BPF_MOV | BPF_K))) {
                *to++ = BPF_ALU64_REG(BPF_XOR, from->dst_reg, from->dst_reg);
                goto out;
        }

        switch (from->code) {
        case BPF_ALU | BPF_ADD | BPF_K:
        case BPF_ALU | BPF_SUB | BPF_K:
        case BPF_ALU | BPF_AND | BPF_K:
        case BPF_ALU | BPF_OR  | BPF_K:
        case BPF_ALU | BPF_XOR | BPF_K:
        case BPF_ALU | BPF_MUL | BPF_K:
        case BPF_ALU | BPF_MOV | BPF_K:
        case BPF_ALU | BPF_DIV | BPF_K:
        case BPF_ALU | BPF_MOD | BPF_K:
                *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
                *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
                *to++ = BPF_ALU32_REG(from->code, from->dst_reg, BPF_REG_AX);
                break;

        case BPF_ALU64 | BPF_ADD | BPF_K:
        case BPF_ALU64 | BPF_SUB | BPF_K:
        case BPF_ALU64 | BPF_AND | BPF_K:
        case BPF_ALU64 | BPF_OR  | BPF_K:
        case BPF_ALU64 | BPF_XOR | BPF_K:
        case BPF_ALU64 | BPF_MUL | BPF_K:
        case BPF_ALU64 | BPF_MOV | BPF_K:
        case BPF_ALU64 | BPF_DIV | BPF_K:
        case BPF_ALU64 | BPF_MOD | BPF_K:
                *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
                *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
                *to++ = BPF_ALU64_REG(from->code, from->dst_reg, BPF_REG_AX);
                break;

        case BPF_JMP | BPF_JEQ  | BPF_K:
        case BPF_JMP | BPF_JNE  | BPF_K:
        case BPF_JMP | BPF_JGT  | BPF_K:
        case BPF_JMP | BPF_JLT  | BPF_K:
        case BPF_JMP | BPF_JGE  | BPF_K:
        case BPF_JMP | BPF_JLE  | BPF_K:
        case BPF_JMP | BPF_JSGT | BPF_K:
        case BPF_JMP | BPF_JSLT | BPF_K:
        case BPF_JMP | BPF_JSGE | BPF_K:
        case BPF_JMP | BPF_JSLE | BPF_K:
        case BPF_JMP | BPF_JSET | BPF_K:
                /* Accommodate for extra offset in case of a backjump. */
                off = from->off;
                if (off < 0)
                        off -= 2;
                *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
                *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
                *to++ = BPF_JMP_REG(from->code, from->dst_reg, BPF_REG_AX, off);
                break;

        case BPF_LD | BPF_IMM | BPF_DW:
                *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[1].imm);
                *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
                *to++ = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
                *to++ = BPF_ALU64_REG(BPF_MOV, aux[0].dst_reg, BPF_REG_AX);
                break;
        case 0: /* Part 2 of BPF_LD | BPF_IMM | BPF_DW. */
                *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[0].imm);
                *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
                *to++ = BPF_ALU64_REG(BPF_OR,  aux[0].dst_reg, BPF_REG_AX);
                break;

        case BPF_ST | BPF_MEM | BPF_DW:
        case BPF_ST | BPF_MEM | BPF_W:
        case BPF_ST | BPF_MEM | BPF_H:
        case BPF_ST | BPF_MEM | BPF_B:
                *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
                *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
                *to++ = BPF_STX_MEM(from->code, from->dst_reg, BPF_REG_AX, from->off);
                break;
        }
out:
        return to - to_buff;
}

static struct bpf_prog *bpf_prog_clone_create(struct bpf_prog *fp_other,
                                              gfp_t gfp_extra_flags)
{
        gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
        struct bpf_prog *fp;

        fp = __vmalloc(fp_other->pages * PAGE_SIZE, gfp_flags, PAGE_KERNEL);
        if (fp != NULL) {
                /* aux->prog still points to the fp_other one, so
                 * when promoting the clone to the real program,
                 * this still needs to be adapted.
                 */
                memcpy(fp, fp_other, fp_other->pages * PAGE_SIZE);
        }

        return fp;
}

static void bpf_prog_clone_free(struct bpf_prog *fp)
{
        /* aux was stolen by the other clone, so we cannot free
         * it from this path! It will be freed eventually by the
         * other program on release.
         *
         * At this point, we don't need a deferred release since
         * clone is guaranteed to not be locked.
         */
        fp->aux = NULL;
        __bpf_prog_free(fp);
}

void bpf_jit_prog_release_other(struct bpf_prog *fp, struct bpf_prog *fp_other)
{
        /* We have to repoint aux->prog to self, as we don't
         * know whether fp here is the clone or the original.
         */
        fp->aux->prog = fp;
        bpf_prog_clone_free(fp_other);
}

struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog)
{
        struct bpf_insn insn_buff[16], aux[2];
        struct bpf_prog *clone, *tmp;
        int insn_delta, insn_cnt;
        struct bpf_insn *insn;
        int i, rewritten;

        if (!bpf_jit_blinding_enabled(prog) || prog->blinded)
                return prog;

        clone = bpf_prog_clone_create(prog, GFP_USER);
        if (!clone)
                return ERR_PTR(-ENOMEM);

        insn_cnt = clone->len;
        insn = clone->insnsi;

        for (i = 0; i < insn_cnt; i++, insn++) {
                /* We temporarily need to hold the original ld64 insn
                 * so that we can still access the first part in the
                 * second blinding run.
                 */
                if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW) &&
                    insn[1].code == 0)
                        memcpy(aux, insn, sizeof(aux));

                rewritten = bpf_jit_blind_insn(insn, aux, insn_buff);
                if (!rewritten)
                        continue;

                tmp = bpf_patch_insn_single(clone, i, insn_buff, rewritten);
                if (!tmp) {
                        /* Patching may have repointed aux->prog during
                         * realloc from the original one, so we need to
                         * fix it up here on error.
                         */
                        bpf_jit_prog_release_other(prog, clone);
                        return ERR_PTR(-ENOMEM);
                }

                clone = tmp;
                insn_delta = rewritten - 1;

                /* Walk new program and skip insns we just inserted. */
                insn = clone->insnsi + i + insn_delta;
                insn_cnt += insn_delta;
                i        += insn_delta;
        }

        clone->blinded = 1;
        return clone;
}
#endif /* CONFIG_BPF_JIT */

/* Base function for offset calculation. Needs to go into .text section,
 * therefore keeping it non-static as well; will also be used by JITs
 * anyway later on, so do not let the compiler omit it. This also needs
 * to go into kallsyms for correlation from e.g. bpftool, so naming
 * must not change.
 */
noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
        return 0;
}
EXPORT_SYMBOL_GPL(__bpf_call_base);

/* All UAPI available opcodes. */
#define BPF_INSN_MAP(INSN_2, INSN_3)            \
        /* 32 bit ALU operations. */            \
        /*   Register based. */                 \
        INSN_3(ALU, ADD,  X),                   \
        INSN_3(ALU, SUB,  X),                   \
        INSN_3(ALU, AND,  X),                   \
        INSN_3(ALU, OR,   X),                   \
        INSN_3(ALU, LSH,  X),                   \
        INSN_3(ALU, RSH,  X),                   \
        INSN_3(ALU, XOR,  X),                   \
        INSN_3(ALU, MUL,  X),                   \
        INSN_3(ALU, MOV,  X),                   \
        INSN_3(ALU, ARSH, X),                   \
        INSN_3(ALU, DIV,  X),                   \
        INSN_3(ALU, MOD,  X),                   \
        INSN_2(ALU, NEG),                       \
        INSN_3(ALU, END, TO_BE),                \
        INSN_3(ALU, END, TO_LE),                \
        /*   Immediate based. */                \
        INSN_3(ALU, ADD,  K),                   \
        INSN_3(ALU, SUB,  K),                   \
        INSN_3(ALU, AND,  K),                   \
        INSN_3(ALU, OR,   K),                   \
        INSN_3(ALU, LSH,  K),                   \
        INSN_3(ALU, RSH,  K),                   \
        INSN_3(ALU, XOR,  K),                   \
        INSN_3(ALU, MUL,  K),                   \
        INSN_3(ALU, MOV,  K),                   \
        INSN_3(ALU, ARSH, K),                   \
        INSN_3(ALU, DIV,  K),                   \
        INSN_3(ALU, MOD,  K),                   \
        /* 64 bit ALU operations. */            \
        /*   Register based. */                 \
        INSN_3(ALU64, ADD,  X),                 \
        INSN_3(ALU64, SUB,  X),                 \
        INSN_3(ALU64, AND,  X),                 \
        INSN_3(ALU64, OR,   X),                 \
        INSN_3(ALU64, LSH,  X),                 \
        INSN_3(ALU64, RSH,  X),                 \
        INSN_3(ALU64, XOR,  X),                 \
        INSN_3(ALU64, MUL,  X),                 \
        INSN_3(ALU64, MOV,  X),                 \
        INSN_3(ALU64, ARSH, X),                 \
        INSN_3(ALU64, DIV,  X),                 \
        INSN_3(ALU64, MOD,  X),                 \
        INSN_2(ALU64, NEG),                     \
        /*   Immediate based. */                \
        INSN_3(ALU64, ADD,  K),                 \
        INSN_3(ALU64, SUB,  K),                 \
        INSN_3(ALU64, AND,  K),                 \
        INSN_3(ALU64, OR,   K),                 \
        INSN_3(ALU64, LSH,  K),                 \
        INSN_3(ALU64, RSH,  K),                 \
        INSN_3(ALU64, XOR,  K),                 \
        INSN_3(ALU64, MUL,  K),                 \
        INSN_3(ALU64, MOV,  K),                 \
        INSN_3(ALU64, ARSH, K),                 \
        INSN_3(ALU64, DIV,  K),                 \
        INSN_3(ALU64, MOD,  K),                 \
        /* Call instruction. */                 \
        INSN_2(JMP, CALL),                      \
        /* Exit instruction. */                 \
        INSN_2(JMP, EXIT),                      \
        /* Jump instructions. */                \
        /*   Register based. */                 \
        INSN_3(JMP, JEQ,  X),                   \
        INSN_3(JMP, JNE,  X),                   \
        INSN_3(JMP, JGT,  X),                   \
        INSN_3(JMP, JLT,  X),                   \
        INSN_3(JMP, JGE,  X),                   \
        INSN_3(JMP, JLE,  X),                   \
        INSN_3(JMP, JSGT, X),                   \
        INSN_3(JMP, JSLT, X),                   \
        INSN_3(JMP, JSGE, X),                   \
        INSN_3(JMP, JSLE, X),                   \
        INSN_3(JMP, JSET, X),                   \
        /*   Immediate based. */                \
        INSN_3(JMP, JEQ,  K),                   \
        INSN_3(JMP, JNE,  K),                   \
        INSN_3(JMP, JGT,  K),                   \
        INSN_3(JMP, JLT,  K),                   \
        INSN_3(JMP, JGE,  K),                   \
        INSN_3(JMP, JLE,  K),                   \
        INSN_3(JMP, JSGT, K),                   \
        INSN_3(JMP, JSLT, K),                   \
        INSN_3(JMP, JSGE, K),                   \
        INSN_3(JMP, JSLE, K),                   \
        INSN_3(JMP, JSET, K),                   \
        INSN_2(JMP, JA),                        \
        /* Store instructions. */               \
        /*   Register based. */                 \
        INSN_3(STX, MEM,  B),                   \
        INSN_3(STX, MEM,  H),                   \
        INSN_3(STX, MEM,  W),                   \
        INSN_3(STX, MEM,  DW),                  \
        INSN_3(STX, XADD, W),                   \
        INSN_3(STX, XADD, DW),                  \
        /*   Immediate based. */                \
        INSN_3(ST, MEM, B),                     \
        INSN_3(ST, MEM, H),                     \
        INSN_3(ST, MEM, W),                     \
        INSN_3(ST, MEM, DW),                    \
        /* Load instructions. */                \
        /*   Register based. */                 \
        INSN_3(LDX, MEM, B),                    \
        INSN_3(LDX, MEM, H),                    \
        INSN_3(LDX, MEM, W),                    \
        INSN_3(LDX, MEM, DW),                   \
        /*   Immediate based. */                \
        INSN_3(LD, IMM, DW)

bool bpf_opcode_in_insntable(u8 code)
{
#define BPF_INSN_2_TBL(x, y)    [BPF_##x | BPF_##y] = true
#define BPF_INSN_3_TBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = true
        static const bool public_insntable[256] = {
                [0 ... 255] = false,
                /* Now overwrite non-defaults ... */
                BPF_INSN_MAP(BPF_INSN_2_TBL, BPF_INSN_3_TBL),
                /* UAPI exposed, but rewritten opcodes. cBPF carry-over. */
                [BPF_LD | BPF_ABS | BPF_B] = true,
                [BPF_LD | BPF_ABS | BPF_H] = true,
                [BPF_LD | BPF_ABS | BPF_W] = true,
                [BPF_LD | BPF_IND | BPF_B] = true,
                [BPF_LD | BPF_IND | BPF_H] = true,
                [BPF_LD | BPF_IND | BPF_W] = true,
        };
#undef BPF_INSN_3_TBL
#undef BPF_INSN_2_TBL
        return public_insntable[code];
}

#ifndef CONFIG_BPF_JIT_ALWAYS_ON
/**
 *      __bpf_prog_run - run eBPF program on a given context
 *      @ctx: is the data we are operating on
 *      @insn: is the array of eBPF instructions
 *
 * Decode and execute eBPF instructions.
 */
static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack)
{
#define BPF_INSN_2_LBL(x, y)    [BPF_##x | BPF_##y] = &&x##_##y
#define BPF_INSN_3_LBL(x, y, z) [BPF_##x | BPF_##y | BPF_##z] = &&x##_##y##_##z
        static const void *jumptable[256] = {
                [0 ... 255] = &&default_label,
                /* Now overwrite non-defaults ... */
                BPF_INSN_MAP(BPF_INSN_2_LBL, BPF_INSN_3_LBL),
                /* Non-UAPI available opcodes. */
                [BPF_JMP | BPF_CALL_ARGS] = &&JMP_CALL_ARGS,
                [BPF_JMP | BPF_TAIL_CALL] = &&JMP_TAIL_CALL,
        };
#undef BPF_INSN_3_LBL
#undef BPF_INSN_2_LBL
        u32 tail_call_cnt = 0;

#define CONT     ({ insn++; goto select_insn; })
#define CONT_JMP ({ insn++; goto select_insn; })

select_insn:
        goto *jumptable[insn->code];

        /* ALU */
#define ALU(OPCODE, OP)                 \
        ALU64_##OPCODE##_X:             \
                DST = DST OP SRC;       \
                CONT;                   \
        ALU_##OPCODE##_X:               \
                DST = (u32) DST OP (u32) SRC;   \
                CONT;                   \
        ALU64_##OPCODE##_K:             \
                DST = DST OP IMM;               \
                CONT;                   \
        ALU_##OPCODE##_K:               \
                DST = (u32) DST OP (u32) IMM;   \
                CONT;

        ALU(ADD,  +)
        ALU(SUB,  -)
        ALU(AND,  &)
        ALU(OR,   |)
        ALU(LSH, <<)
        ALU(RSH, >>)
        ALU(XOR,  ^)
        ALU(MUL,  *)
#undef ALU
        ALU_NEG:
                DST = (u32) -DST;
                CONT;
        ALU64_NEG:
                DST = -DST;
                CONT;
        ALU_MOV_X:
                DST = (u32) SRC;
                CONT;
        ALU_MOV_K:
                DST = (u32) IMM;
                CONT;
        ALU64_MOV_X:
                DST = SRC;
                CONT;
        ALU64_MOV_K:
                DST = IMM;
                CONT;
        LD_IMM_DW:
                DST = (u64) (u32) insn[0].imm | ((u64) (u32) insn[1].imm) << 32;
                insn++;
                CONT;
        ALU_ARSH_X:
                DST = (u64) (u32) ((*(s32 *) &DST) >> SRC);
                CONT;
        ALU_ARSH_K:
                DST = (u64) (u32) ((*(s32 *) &DST) >> IMM);
                CONT;
        ALU64_ARSH_X:
                (*(s64 *) &DST) >>= SRC;
                CONT;
        ALU64_ARSH_K:
                (*(s64 *) &DST) >>= IMM;
                CONT;
        ALU64_MOD_X:
                div64_u64_rem(DST, SRC, &AX);
                DST = AX;
                CONT;
        ALU_MOD_X:
                AX = (u32) DST;
                DST = do_div(AX, (u32) SRC);
                CONT;
        ALU64_MOD_K:
                div64_u64_rem(DST, IMM, &AX);
                DST = AX;
                CONT;
        ALU_MOD_K:
                AX = (u32) DST;
                DST = do_div(AX, (u32) IMM);
                CONT;
        ALU64_DIV_X:
                DST = div64_u64(DST, SRC);
                CONT;
        ALU_DIV_X:
                AX = (u32) DST;
                do_div(AX, (u32) SRC);
                DST = (u32) AX;
                CONT;
        ALU64_DIV_K:
                DST = div64_u64(DST, IMM);
                CONT;
        ALU_DIV_K:
                AX = (u32) DST;
                do_div(AX, (u32) IMM);
                DST = (u32) AX;
                CONT;
        ALU_END_TO_BE:
                switch (IMM) {
                case 16:
                        DST = (__force u16) cpu_to_be16(DST);
                        break;
                case 32:
                        DST = (__force u32) cpu_to_be32(DST);
                        break;
                case 64:
                        DST = (__force u64) cpu_to_be64(DST);
                        break;
                }
                CONT;
        ALU_END_TO_LE:
                switch (IMM) {
                case 16:
                        DST = (__force u16) cpu_to_le16(DST);
                        break;
                case 32:
                        DST = (__force u32) cpu_to_le32(DST);
                        break;
                case 64:
                        DST = (__force u64) cpu_to_le64(DST);
                        break;
                }
                CONT;

        /* CALL */
        JMP_CALL:
                /* Function call scratches BPF_R1-BPF_R5 registers,
                 * preserves BPF_R6-BPF_R9, and stores return value
                 * into BPF_R0.
                 */
                BPF_R0 = (__bpf_call_base + insn->imm)(BPF_R1, BPF_R2, BPF_R3,
                                                       BPF_R4, BPF_R5);
                CONT;

        JMP_CALL_ARGS:
                BPF_R0 = (__bpf_call_base_args + insn->imm)(BPF_R1, BPF_R2,
                                                            BPF_R3, BPF_R4,
                                                            BPF_R5,
                                                            insn + insn->off + 1);
                CONT;

        JMP_TAIL_CALL: {
                struct bpf_map *map = (struct bpf_map *) (unsigned long) BPF_R2;
                struct bpf_array *array = container_of(map, struct bpf_array, map);
                struct bpf_prog *prog;
                u32 index = BPF_R3;

                if (unlikely(index >= array->map.max_entries))
                        goto out;
                if (unlikely(tail_call_cnt > MAX_TAIL_CALL_CNT))
                        goto out;

                tail_call_cnt++;

                prog = READ_ONCE(array->ptrs[index]);
                if (!prog)
                        goto out;

                /* ARG1 at this point is guaranteed to point to CTX from
                 * the verifier side due to the fact that the tail call is
                 * handeled like a helper, that is, bpf_tail_call_proto,
                 * where arg1_type is ARG_PTR_TO_CTX.
                 */
                insn = prog->insnsi;
                goto select_insn;
out:
                CONT;
        }
        /* JMP */
        JMP_JA:
                insn += insn->off;
                CONT;
        JMP_JEQ_X:
                if (DST == SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JEQ_K:
                if (DST == IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JNE_X:
                if (DST != SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JNE_K:
                if (DST != IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JGT_X:
                if (DST > SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JGT_K:
                if (DST > IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JLT_X:
                if (DST < SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JLT_K:
                if (DST < IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JGE_X:
                if (DST >= SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JGE_K:
                if (DST >= IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JLE_X:
                if (DST <= SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JLE_K:
                if (DST <= IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSGT_X:
                if (((s64) DST) > ((s64) SRC)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSGT_K:
                if (((s64) DST) > ((s64) IMM)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSLT_X:
                if (((s64) DST) < ((s64) SRC)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSLT_K:
                if (((s64) DST) < ((s64) IMM)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSGE_X:
                if (((s64) DST) >= ((s64) SRC)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSGE_K:
                if (((s64) DST) >= ((s64) IMM)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSLE_X:
                if (((s64) DST) <= ((s64) SRC)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSLE_K:
                if (((s64) DST) <= ((s64) IMM)) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSET_X:
                if (DST & SRC) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_JSET_K:
                if (DST & IMM) {
                        insn += insn->off;
                        CONT_JMP;
                }
                CONT;
        JMP_EXIT:
                return BPF_R0;

        /* STX and ST and LDX*/
#define LDST(SIZEOP, SIZE)                                              \
        STX_MEM_##SIZEOP:                                               \
                *(SIZE *)(unsigned long) (DST + insn->off) = SRC;       \
                CONT;                                                   \
        ST_MEM_##SIZEOP:                                                \
                *(SIZE *)(unsigned long) (DST + insn->off) = IMM;       \
                CONT;                                                   \
        LDX_MEM_##SIZEOP:                                               \
                DST = *(SIZE *)(unsigned long) (SRC + insn->off);       \
                CONT;

        LDST(B,   u8)
        LDST(H,  u16)
        LDST(W,  u32)
        LDST(DW, u64)
#undef LDST
        STX_XADD_W: /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */
                atomic_add((u32) SRC, (atomic_t *)(unsigned long)
                           (DST + insn->off));
                CONT;
        STX_XADD_DW: /* lock xadd *(u64 *)(dst_reg + off16) += src_reg */
                atomic64_add((u64) SRC, (atomic64_t *)(unsigned long)
                             (DST + insn->off));
                CONT;

        default_label:
                /* If we ever reach this, we have a bug somewhere. Die hard here
                 * instead of just returning 0; we could be somewhere in a subprog,
                 * so execution could continue otherwise which we do /not/ want.
                 *
                 * Note, verifier whitelists all opcodes in bpf_opcode_in_insntable().
                 */
                pr_warn("BPF interpreter: unknown opcode %02x\n", insn->code);
                BUG_ON(1);
                return 0;
}
STACK_FRAME_NON_STANDARD(___bpf_prog_run); /* jump table */

#define PROG_NAME(stack_size) __bpf_prog_run##stack_size
#define DEFINE_BPF_PROG_RUN(stack_size) \
static unsigned int PROG_NAME(stack_size)(const void *ctx, const struct bpf_insn *insn) \
{ \
        u64 stack[stack_size / sizeof(u64)]; \
        u64 regs[MAX_BPF_EXT_REG]; \
\
        FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)]; \
        ARG1 = (u64) (unsigned long) ctx; \
        return ___bpf_prog_run(regs, insn, stack); \
}

#define PROG_NAME_ARGS(stack_size) __bpf_prog_run_args##stack_size
#define DEFINE_BPF_PROG_RUN_ARGS(stack_size) \
static u64 PROG_NAME_ARGS(stack_size)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5, \
                                      const struct bpf_insn *insn) \
{ \
        u64 stack[stack_size / sizeof(u64)]; \
        u64 regs[MAX_BPF_EXT_REG]; \
\
        FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)]; \
        BPF_R1 = r1; \
        BPF_R2 = r2; \
        BPF_R3 = r3; \
        BPF_R4 = r4; \
        BPF_R5 = r5; \
        return ___bpf_prog_run(regs, insn, stack); \
}

#define EVAL1(FN, X) FN(X)
#define EVAL2(FN, X, Y...) FN(X) EVAL1(FN, Y)
#define EVAL3(FN, X, Y...) FN(X) EVAL2(FN, Y)
#define EVAL4(FN, X, Y...) FN(X) EVAL3(FN, Y)
#define EVAL5(FN, X, Y...) FN(X) EVAL4(FN, Y)
#define EVAL6(FN, X, Y...) FN(X) EVAL5(FN, Y)

EVAL6(DEFINE_BPF_PROG_RUN, 32, 64, 96, 128, 160, 192);
EVAL6(DEFINE_BPF_PROG_RUN, 224, 256, 288, 320, 352, 384);
EVAL4(DEFINE_BPF_PROG_RUN, 416, 448, 480, 512);

EVAL6(DEFINE_BPF_PROG_RUN_ARGS, 32, 64, 96, 128, 160, 192);
EVAL6(DEFINE_BPF_PROG_RUN_ARGS, 224, 256, 288, 320, 352, 384);
EVAL4(DEFINE_BPF_PROG_RUN_ARGS, 416, 448, 480, 512);

#define PROG_NAME_LIST(stack_size) PROG_NAME(stack_size),

static unsigned int (*interpreters[])(const void *ctx,
                                      const struct bpf_insn *insn) = {
EVAL6(PROG_NAME_LIST, 32, 64, 96, 128, 160, 192)
EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
#undef PROG_NAME_LIST
#define PROG_NAME_LIST(stack_size) PROG_NAME_ARGS(stack_size),
static u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
                                  const struct bpf_insn *insn) = {
EVAL6(PROG_NAME_LIST, 32, 64, 96, 128, 160, 192)
EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
#undef PROG_NAME_LIST

void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
{
        stack_depth = max_t(u32, stack_depth, 1);
        insn->off = (s16) insn->imm;
        insn->imm = interpreters_args[(round_up(stack_depth, 32) / 32) - 1] -
                __bpf_call_base_args;
        insn->code = BPF_JMP | BPF_CALL_ARGS;
}

#else
static unsigned int __bpf_prog_ret0_warn(const void *ctx,
                                         const struct bpf_insn *insn)
{
        /* If this handler ever gets executed, then BPF_JIT_ALWAYS_ON
         * is not working properly, so warn about it!
         */
        WARN_ON_ONCE(1);
        return 0;
}
#endif

bool bpf_prog_array_compatible(struct bpf_array *array,
                               const struct bpf_prog *fp)
{
        if (fp->kprobe_override)
                return false;

        if (!array->owner_prog_type) {
                /* There's no owner yet where we could check for
                 * compatibility.
                 */
                array->owner_prog_type = fp->type;
                array->owner_jited = fp->jited;

                return true;
        }

        return array->owner_prog_type == fp->type &&
               array->owner_jited == fp->jited;
}

static int bpf_check_tail_call(const struct bpf_prog *fp)
{
        struct bpf_prog_aux *aux = fp->aux;
        int i;

        for (i = 0; i < aux->used_map_cnt; i++) {
                struct bpf_map *map = aux->used_maps[i];
                struct bpf_array *array;

                if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
                        continue;

                array = container_of(map, struct bpf_array, map);
                if (!bpf_prog_array_compatible(array, fp))
                        return -EINVAL;
        }

        return 0;
}

static void bpf_prog_select_func(struct bpf_prog *fp)
{
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
        u32 stack_depth = max_t(u32, fp->aux->stack_depth, 1);

        fp->bpf_func = interpreters[(round_up(stack_depth, 32) / 32) - 1];
#else
        fp->bpf_func = __bpf_prog_ret0_warn;
#endif
}

/**
 *      bpf_prog_select_runtime - select exec runtime for BPF program
 *      @fp: bpf_prog populated with internal BPF program
 *      @err: pointer to error variable
 *
 * Try to JIT eBPF program, if JIT is not available, use interpreter.
 * The BPF program will be executed via BPF_PROG_RUN() macro.
 */
struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
{
        /* In case of BPF to BPF calls, verifier did all the prep
         * work with regards to JITing, etc.
         */
        if (fp->bpf_func)
                goto finalize;

        bpf_prog_select_func(fp);

        /* eBPF JITs can rewrite the program in case constant
         * blinding is active. However, in case of error during
         * blinding, bpf_int_jit_compile() must always return a
         * valid program, which in this case would simply not
         * be JITed, but falls back to the interpreter.
         */
        if (!bpf_prog_is_dev_bound(fp->aux)) {
                *err = bpf_prog_alloc_jited_linfo(fp);
                if (*err)
                        return fp;

                fp = bpf_int_jit_compile(fp);
                if (!fp->jited) {
                        bpf_prog_free_jited_linfo(fp);
#ifdef CONFIG_BPF_JIT_ALWAYS_ON
                        *err = -ENOTSUPP;
                        return fp;
#endif
                } else {
                        bpf_prog_free_unused_jited_linfo(fp);
                }
        } else {
                *err = bpf_prog_offload_compile(fp);
                if (*err)
                        return fp;
        }

finalize:
        bpf_prog_lock_ro(fp);

        /* The tail call compatibility check can only be done at
         * this late stage as we need to determine, if we deal
         * with JITed or non JITed program concatenations and not
         * all eBPF JITs might immediately support all features.
         */
        *err = bpf_check_tail_call(fp);

        return fp;
}
EXPORT_SYMBOL_GPL(bpf_prog_select_runtime);

static unsigned int __bpf_prog_ret1(const void *ctx,
                                    const struct bpf_insn *insn)
{
        return 1;
}

static struct bpf_prog_dummy {
        struct bpf_prog prog;
} dummy_bpf_prog = {
        .prog = {
                .bpf_func = __bpf_prog_ret1,
        },
};

/* to avoid allocating empty bpf_prog_array for cgroups that
 * don't have bpf program attached use one global 'empty_prog_array'
 * It will not be modified the caller of bpf_prog_array_alloc()
 * (since caller requested prog_cnt == 0)
 * that pointer should be 'freed' by bpf_prog_array_free()
 */
static struct {
        struct bpf_prog_array hdr;
        struct bpf_prog *null_prog;
} empty_prog_array = {
        .null_prog = NULL,
};

struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags)
{
        if (prog_cnt)
                return kzalloc(sizeof(struct bpf_prog_array) +
                               sizeof(struct bpf_prog_array_item) *
                               (prog_cnt + 1),
                               flags);

        return &empty_prog_array.hdr;
}

void bpf_prog_array_free(struct bpf_prog_array __rcu *progs)
{
        if (!progs ||
            progs == (struct bpf_prog_array __rcu *)&empty_prog_array.hdr)
                return;
        kfree_rcu(progs, rcu);
}

int bpf_prog_array_length(struct bpf_prog_array __rcu *array)
{
        struct bpf_prog_array_item *item;
        u32 cnt = 0;

        rcu_read_lock();
        item = rcu_dereference(array)->items;
        for (; item->prog; item++)
                if (item->prog != &dummy_bpf_prog.prog)
                        cnt++;
        rcu_read_unlock();
        return cnt;
}


static bool bpf_prog_array_copy_core(struct bpf_prog_array __rcu *array,
                                     u32 *prog_ids,
                                     u32 request_cnt)
{
        struct bpf_prog_array_item *item;
        int i = 0;

        item = rcu_dereference_check(array, 1)->items;
        for (; item->prog; item++) {
                if (item->prog == &dummy_bpf_prog.prog)
                        continue;
                prog_ids[i] = item->prog->aux->id;
                if (++i == request_cnt) {
                        item++;
                        break;
                }
        }

        return !!(item->prog);
}

int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *array,
                                __u32 __user *prog_ids, u32 cnt)
{
        unsigned long err = 0;
        bool nospc;
        u32 *ids;

        /* users of this function are doing:
         * cnt = bpf_prog_array_length();
         * if (cnt > 0)
         *     bpf_prog_array_copy_to_user(..., cnt);
         * so below kcalloc doesn't need extra cnt > 0 check, but
         * bpf_prog_array_length() releases rcu lock and
         * prog array could have been swapped with empty or larger array,
         * so always copy 'cnt' prog_ids to the user.
         * In a rare race the user will see zero prog_ids
         */
        ids = kcalloc(cnt, sizeof(u32), GFP_USER | __GFP_NOWARN);
        if (!ids)
                return -ENOMEM;
        rcu_read_lock();
        nospc = bpf_prog_array_copy_core(array, ids, cnt);
        rcu_read_unlock();
        err = copy_to_user(prog_ids, ids, cnt * sizeof(u32));
        kfree(ids);
        if (err)
                return -EFAULT;
        if (nospc)
                return -ENOSPC;
        return 0;
}

void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *array,
                                struct bpf_prog *old_prog)
{
        struct bpf_prog_array_item *item = array->items;

        for (; item->prog; item++)
                if (item->prog == old_prog) {
                        WRITE_ONCE(item->prog, &dummy_bpf_prog.prog);
                        break;
                }
}

int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
                        struct bpf_prog *exclude_prog,
                        struct bpf_prog *include_prog,
                        struct bpf_prog_array **new_array)
{
        int new_prog_cnt, carry_prog_cnt = 0;
        struct bpf_prog_array_item *existing;
        struct bpf_prog_array *array;
        bool found_exclude = false;
        int new_prog_idx = 0;

        /* Figure out how many existing progs we need to carry over to
         * the new array.
         */
        if (old_array) {
                existing = old_array->items;
                for (; existing->prog; existing++) {
                        if (existing->prog == exclude_prog) {
                                found_exclude = true;
                                continue;
                        }
                        if (existing->prog != &dummy_bpf_prog.prog)
                                carry_prog_cnt++;
                        if (existing->prog == include_prog)
                                return -EEXIST;
                }
        }

        if (exclude_prog && !found_exclude)
                return -ENOENT;

        /* How many progs (not NULL) will be in the new array? */
        new_prog_cnt = carry_prog_cnt;
        if (include_prog)
                new_prog_cnt += 1;

        /* Do we have any prog (not NULL) in the new array? */
        if (!new_prog_cnt) {
                *new_array = NULL;
                return 0;
        }

        /* +1 as the end of prog_array is marked with NULL */
        array = bpf_prog_array_alloc(new_prog_cnt + 1, GFP_KERNEL);
        if (!array)
                return -ENOMEM;

        /* Fill in the new prog array */
        if (carry_prog_cnt) {
                existing = old_array->items;
                for (; existing->prog; existing++)
                        if (existing->prog != exclude_prog &&
                            existing->prog != &dummy_bpf_prog.prog) {
                                array->items[new_prog_idx++].prog =
                                        existing->prog;
                        }
        }
        if (include_prog)
                array->items[new_prog_idx++].prog = include_prog;
        array->items[new_prog_idx].prog = NULL;
        *new_array = array;
        return 0;
}

int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
                             u32 *prog_ids, u32 request_cnt,
                             u32 *prog_cnt)
{
        u32 cnt = 0;

        if (array)
                cnt = bpf_prog_array_length(array);

        *prog_cnt = cnt;

        /* return early if user requested only program count or nothing to copy */
        if (!request_cnt || !cnt)
                return 0;

        /* this function is called under trace/bpf_trace.c: bpf_event_mutex */
        return bpf_prog_array_copy_core(array, prog_ids, request_cnt) ? -ENOSPC
                                                                     : 0;
}

static void bpf_prog_free_deferred(struct work_struct *work)
{
        struct bpf_prog_aux *aux;
        int i;

        aux = container_of(work, struct bpf_prog_aux, work);
        if (bpf_prog_is_dev_bound(aux))
                bpf_prog_offload_destroy(aux->prog);
#ifdef CONFIG_PERF_EVENTS
        if (aux->prog->has_callchain_buf)
                put_callchain_buffers();
#endif
        for (i = 0; i < aux->func_cnt; i++)
                bpf_jit_free(aux->func[i]);
        if (aux->func_cnt) {
                kfree(aux->func);
                bpf_prog_unlock_free(aux->prog);
        } else {
                bpf_jit_free(aux->prog);
        }
}

/* Free internal BPF program */
void bpf_prog_free(struct bpf_prog *fp)
{
        struct bpf_prog_aux *aux = fp->aux;

        INIT_WORK(&aux->work, bpf_prog_free_deferred);
        schedule_work(&aux->work);
}
EXPORT_SYMBOL_GPL(bpf_prog_free);

/* RNG for unpriviledged user space with separated state from prandom_u32(). */
static DEFINE_PER_CPU(struct rnd_state, bpf_user_rnd_state);

void bpf_user_rnd_init_once(void)
{
        prandom_init_once(&bpf_user_rnd_state);
}

BPF_CALL_0(bpf_user_rnd_u32)
{
        /* Should someone ever have the rather unwise idea to use some
         * of the registers passed into this function, then note that
         * this function is called from native eBPF and classic-to-eBPF
         * transformations. Register assignments from both sides are
         * different, f.e. classic always sets fn(ctx, A, X) here.
         */
        struct rnd_state *state;
        u32 res;

        state = &get_cpu_var(bpf_user_rnd_state);
        res = prandom_u32_state(state);
        put_cpu_var(bpf_user_rnd_state);

        return res;
}

/* Weak definitions of helper functions in case we don't have bpf syscall. */
const struct bpf_func_proto bpf_map_lookup_elem_proto __weak;
const struct bpf_func_proto bpf_map_update_elem_proto __weak;
const struct bpf_func_proto bpf_map_delete_elem_proto __weak;
const struct bpf_func_proto bpf_map_push_elem_proto __weak;
const struct bpf_func_proto bpf_map_pop_elem_proto __weak;
const struct bpf_func_proto bpf_map_peek_elem_proto __weak;

const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
const struct bpf_func_proto bpf_get_numa_node_id_proto __weak;
const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;

const struct bpf_func_proto bpf_get_current_pid_tgid_proto __weak;
const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
const struct bpf_func_proto bpf_get_current_comm_proto __weak;
const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
const struct bpf_func_proto bpf_get_local_storage_proto __weak;

const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
{
        return NULL;
}

u64 __weak
bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
                 void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
{
        return -ENOTSUPP;
}
EXPORT_SYMBOL_GPL(bpf_event_output);

/* Always built-in helper functions. */
const struct bpf_func_proto bpf_tail_call_proto = {
        .func           = NULL,
        .gpl_only       = false,
        .ret_type       = RET_VOID,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_CONST_MAP_PTR,
        .arg3_type      = ARG_ANYTHING,
};

/* Stub for JITs that only support cBPF. eBPF programs are interpreted.
 * It is encouraged to implement bpf_int_jit_compile() instead, so that
 * eBPF and implicitly also cBPF can get JITed!
 */
struct bpf_prog * __weak bpf_int_jit_compile(struct bpf_prog *prog)
{
        return prog;
}

/* Stub for JITs that support eBPF. All cBPF code gets transformed into
 * eBPF by the kernel and is later compiled by bpf_int_jit_compile().
 */
void __weak bpf_jit_compile(struct bpf_prog *prog)
{
}

bool __weak bpf_helper_changes_pkt_data(void *func)
{
        return false;
}

/* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call
 * skb_copy_bits(), so provide a weak definition of it for NET-less config.
 */
int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to,
                         int len)
{
        return -EFAULT;
}

/* All definitions of tracepoints related to BPF. */
#define CREATE_TRACE_POINTS
#include <linux/bpf_trace.h>

EXPORT_TRACEPOINT_SYMBOL_GPL(xdp_exception);