// SPDX-License-Identifier: GPL-2.0
/*
 * Just-In-Time compiler for eBPF filters on IA32 (32bit x86)
 *
 * Author: Wang YanQing (udknight@gmail.com)
 * The code based on code and ideas from:
 * Eric Dumazet (eric.dumazet@gmail.com)
 * and from:
 * Shubham Bansal <illusionist.neo@gmail.com>
 */

#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include <asm/cacheflush.h>
#include <asm/set_memory.h>
#include <asm/nospec-branch.h>
#include <linux/bpf.h>

/*
 * eBPF prog stack layout:
 *
 *                         high
 * original ESP =>        +-----+
 *                        |     | callee saved registers
 *                        +-----+
 *                        | ... | eBPF JIT scratch space
 * BPF_FP,IA32_EBP  =>    +-----+
 *                        | ... | eBPF prog stack
 *                        +-----+
 *                        |RSVD | JIT scratchpad
 * current ESP =>         +-----+
 *                        |     |
 *                        | ... | Function call stack
 *                        |     |
 *                        +-----+
 *                          low
 *
 * The callee saved registers:
 *
 *                                high
 * original ESP =>        +------------------+ \
 *                        |        ebp       | |
 * current EBP =>         +------------------+ } callee saved registers
 *                        |    ebx,esi,edi   | |
 *                        +------------------+ /
 *                                low
 */

static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
{
        if (len == 1)
                *ptr = bytes;
        else if (len == 2)
                *(u16 *)ptr = bytes;
        else {
                *(u32 *)ptr = bytes;
                barrier();
        }
        return ptr + len;
}

#define EMIT(bytes, len) \
        do { prog = emit_code(prog, bytes, len); cnt += len; } while (0)

#define EMIT1(b1)               EMIT(b1, 1)
#define EMIT2(b1, b2)           EMIT((b1) + ((b2) << 8), 2)
#define EMIT3(b1, b2, b3)       EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
#define EMIT4(b1, b2, b3, b4)   \
        EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)

#define EMIT1_off32(b1, off) \
        do { EMIT1(b1); EMIT(off, 4); } while (0)
#define EMIT2_off32(b1, b2, off) \
        do { EMIT2(b1, b2); EMIT(off, 4); } while (0)
#define EMIT3_off32(b1, b2, b3, off) \
        do { EMIT3(b1, b2, b3); EMIT(off, 4); } while (0)
#define EMIT4_off32(b1, b2, b3, b4, off) \
        do { EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0)

#define jmp_label(label, jmp_insn_len) (label - cnt - jmp_insn_len)

static bool is_imm8(int value)
{
        return value <= 127 && value >= -128;
}

static bool is_simm32(s64 value)
{
        return value == (s64) (s32) value;
}

#define STACK_OFFSET(k) (k)
#define TCALL_CNT       (MAX_BPF_JIT_REG + 0)   /* Tail Call Count */

#define IA32_EAX        (0x0)
#define IA32_EBX        (0x3)
#define IA32_ECX        (0x1)
#define IA32_EDX        (0x2)
#define IA32_ESI        (0x6)
#define IA32_EDI        (0x7)
#define IA32_EBP        (0x5)
#define IA32_ESP        (0x4)

/*
 * List of x86 cond jumps opcodes (. + s8)
 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
 */
#define IA32_JB  0x72
#define IA32_JAE 0x73
#define IA32_JE  0x74
#define IA32_JNE 0x75
#define IA32_JBE 0x76
#define IA32_JA  0x77
#define IA32_JL  0x7C
#define IA32_JGE 0x7D
#define IA32_JLE 0x7E
#define IA32_JG  0x7F

/*
 * Map eBPF registers to IA32 32bit registers or stack scratch space.
 *
 * 1. All the registers, R0-R10, are mapped to scratch space on stack.
 * 2. We need two 64 bit temp registers to do complex operations on eBPF
 *    registers.
 * 3. For performance reason, the BPF_REG_AX for blinding constant, is
 *    mapped to real hardware register pair, IA32_ESI and IA32_EDI.
 *
 * As the eBPF registers are all 64 bit registers and IA32 has only 32 bit
 * registers, we have to map each eBPF registers with two IA32 32 bit regs
 * or scratch memory space and we have to build eBPF 64 bit register from those.
 *
 * We use IA32_EAX, IA32_EDX, IA32_ECX, IA32_EBX as temporary registers.
 */
static const u8 bpf2ia32[][2] = {
        /* Return value from in-kernel function, and exit value from eBPF */
        [BPF_REG_0] = {STACK_OFFSET(0), STACK_OFFSET(4)},

        /* The arguments from eBPF program to in-kernel function */
        /* Stored on stack scratch space */
        [BPF_REG_1] = {STACK_OFFSET(8), STACK_OFFSET(12)},
        [BPF_REG_2] = {STACK_OFFSET(16), STACK_OFFSET(20)},
        [BPF_REG_3] = {STACK_OFFSET(24), STACK_OFFSET(28)},
        [BPF_REG_4] = {STACK_OFFSET(32), STACK_OFFSET(36)},
        [BPF_REG_5] = {STACK_OFFSET(40), STACK_OFFSET(44)},

        /* Callee saved registers that in-kernel function will preserve */
        /* Stored on stack scratch space */
        [BPF_REG_6] = {STACK_OFFSET(48), STACK_OFFSET(52)},
        [BPF_REG_7] = {STACK_OFFSET(56), STACK_OFFSET(60)},
        [BPF_REG_8] = {STACK_OFFSET(64), STACK_OFFSET(68)},
        [BPF_REG_9] = {STACK_OFFSET(72), STACK_OFFSET(76)},

        /* Read only Frame Pointer to access Stack */
        [BPF_REG_FP] = {STACK_OFFSET(80), STACK_OFFSET(84)},

        /* Temporary register for blinding constants. */
        [BPF_REG_AX] = {IA32_ESI, IA32_EDI},

        /* Tail call count. Stored on stack scratch space. */
        [TCALL_CNT] = {STACK_OFFSET(88), STACK_OFFSET(92)},
};

#define dst_lo  dst[0]
#define dst_hi  dst[1]
#define src_lo  src[0]
#define src_hi  src[1]

#define STACK_ALIGNMENT 8
/*
 * Stack space for BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4,
 * BPF_REG_5, BPF_REG_6, BPF_REG_7, BPF_REG_8, BPF_REG_9,
 * BPF_REG_FP, BPF_REG_AX and Tail call counts.
 */
#define SCRATCH_SIZE 96

/* Total stack size used in JITed code */
#define _STACK_SIZE     (stack_depth + SCRATCH_SIZE)

#define STACK_SIZE ALIGN(_STACK_SIZE, STACK_ALIGNMENT)

/* Get the offset of eBPF REGISTERs stored on scratch space. */
#define STACK_VAR(off) (off)

/* Encode 'dst_reg' register into IA32 opcode 'byte' */
static u8 add_1reg(u8 byte, u32 dst_reg)
{
        return byte + dst_reg;
}

/* Encode 'dst_reg' and 'src_reg' registers into IA32 opcode 'byte' */
static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg)
{
        return byte + dst_reg + (src_reg << 3);
}

static void jit_fill_hole(void *area, unsigned int size)
{
        /* Fill whole space with int3 instructions */
        memset(area, 0xcc, size);
}

static inline void emit_ia32_mov_i(const u8 dst, const u32 val, bool dstk,
                                   u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;

        if (dstk) {
                if (val == 0) {
                        /* xor eax,eax */
                        EMIT2(0x33, add_2reg(0xC0, IA32_EAX, IA32_EAX));
                        /* mov dword ptr [ebp+off],eax */
                        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
                              STACK_VAR(dst));
                } else {
                        EMIT3_off32(0xC7, add_1reg(0x40, IA32_EBP),
                                    STACK_VAR(dst), val);
                }
        } else {
                if (val == 0)
                        EMIT2(0x33, add_2reg(0xC0, dst, dst));
                else
                        EMIT2_off32(0xC7, add_1reg(0xC0, dst),
                                    val);
        }
        *pprog = prog;
}

/* dst = imm (4 bytes)*/
static inline void emit_ia32_mov_r(const u8 dst, const u8 src, bool dstk,
                                   bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 sreg = sstk ? IA32_EAX : src;

        if (sstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(src));
        if (dstk)
                /* mov dword ptr [ebp+off],eax */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, sreg), STACK_VAR(dst));
        else
                /* mov dst,sreg */
                EMIT2(0x89, add_2reg(0xC0, dst, sreg));

        *pprog = prog;
}

/* dst = src */
static inline void emit_ia32_mov_r64(const bool is64, const u8 dst[],
                                     const u8 src[], bool dstk,
                                     bool sstk, u8 **pprog,
                                     const struct bpf_prog_aux *aux)
{
        emit_ia32_mov_r(dst_lo, src_lo, dstk, sstk, pprog);
        if (is64)
                /* complete 8 byte move */
                emit_ia32_mov_r(dst_hi, src_hi, dstk, sstk, pprog);
        else if (!aux->verifier_zext)
                /* zero out high 4 bytes */
                emit_ia32_mov_i(dst_hi, 0, dstk, pprog);
}

/* Sign extended move */
static inline void emit_ia32_mov_i64(const bool is64, const u8 dst[],
                                     const u32 val, bool dstk, u8 **pprog)
{
        u32 hi = 0;

        if (is64 && (val & (1<<31)))
                hi = (u32)~0;
        emit_ia32_mov_i(dst_lo, val, dstk, pprog);
        emit_ia32_mov_i(dst_hi, hi, dstk, pprog);
}

/*
 * ALU operation (32 bit)
 * dst = dst * src
 */
static inline void emit_ia32_mul_r(const u8 dst, const u8 src, bool dstk,
                                   bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 sreg = sstk ? IA32_ECX : src;

        if (sstk)
                /* mov ecx,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX), STACK_VAR(src));

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(dst));
        else
                /* mov eax,dst */
                EMIT2(0x8B, add_2reg(0xC0, dst, IA32_EAX));


        EMIT2(0xF7, add_1reg(0xE0, sreg));

        if (dstk)
                /* mov dword ptr [ebp+off],eax */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst));
        else
                /* mov dst,eax */
                EMIT2(0x89, add_2reg(0xC0, dst, IA32_EAX));

        *pprog = prog;
}

static inline void emit_ia32_to_le_r64(const u8 dst[], s32 val,
                                         bool dstk, u8 **pprog,
                                         const struct bpf_prog_aux *aux)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk && val != 64) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }
        switch (val) {
        case 16:
                /*
                 * Emit 'movzwl eax,ax' to zero extend 16-bit
                 * into 64 bit
                 */
                EMIT2(0x0F, 0xB7);
                EMIT1(add_2reg(0xC0, dreg_lo, dreg_lo));
                if (!aux->verifier_zext)
                        /* xor dreg_hi,dreg_hi */
                        EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
                break;
        case 32:
                if (!aux->verifier_zext)
                        /* xor dreg_hi,dreg_hi */
                        EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
                break;
        case 64:
                /* nop */
                break;
        }

        if (dstk && val != 64) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        *pprog = prog;
}

static inline void emit_ia32_to_be_r64(const u8 dst[], s32 val,
                                       bool dstk, u8 **pprog,
                                       const struct bpf_prog_aux *aux)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }
        switch (val) {
        case 16:
                /* Emit 'ror %ax, 8' to swap lower 2 bytes */
                EMIT1(0x66);
                EMIT3(0xC1, add_1reg(0xC8, dreg_lo), 8);

                EMIT2(0x0F, 0xB7);
                EMIT1(add_2reg(0xC0, dreg_lo, dreg_lo));

                if (!aux->verifier_zext)
                        /* xor dreg_hi,dreg_hi */
                        EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
                break;
        case 32:
                /* Emit 'bswap eax' to swap lower 4 bytes */
                EMIT1(0x0F);
                EMIT1(add_1reg(0xC8, dreg_lo));

                if (!aux->verifier_zext)
                        /* xor dreg_hi,dreg_hi */
                        EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
                break;
        case 64:
                /* Emit 'bswap eax' to swap lower 4 bytes */
                EMIT1(0x0F);
                EMIT1(add_1reg(0xC8, dreg_lo));

                /* Emit 'bswap edx' to swap lower 4 bytes */
                EMIT1(0x0F);
                EMIT1(add_1reg(0xC8, dreg_hi));

                /* mov ecx,dreg_hi */
                EMIT2(0x89, add_2reg(0xC0, IA32_ECX, dreg_hi));
                /* mov dreg_hi,dreg_lo */
                EMIT2(0x89, add_2reg(0xC0, dreg_hi, dreg_lo));
                /* mov dreg_lo,ecx */
                EMIT2(0x89, add_2reg(0xC0, dreg_lo, IA32_ECX));

                break;
        }
        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        *pprog = prog;
}

/*
 * ALU operation (32 bit)
 * dst = dst (div|mod) src
 */
static inline void emit_ia32_div_mod_r(const u8 op, const u8 dst, const u8 src,
                                       bool dstk, bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;

        if (sstk)
                /* mov ecx,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX),
                      STACK_VAR(src));
        else if (src != IA32_ECX)
                /* mov ecx,src */
                EMIT2(0x8B, add_2reg(0xC0, src, IA32_ECX));

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst));
        else
                /* mov eax,dst */
                EMIT2(0x8B, add_2reg(0xC0, dst, IA32_EAX));

        /* xor edx,edx */
        EMIT2(0x31, add_2reg(0xC0, IA32_EDX, IA32_EDX));
        /* div ecx */
        EMIT2(0xF7, add_1reg(0xF0, IA32_ECX));

        if (op == BPF_MOD) {
                if (dstk)
                        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EDX),
                              STACK_VAR(dst));
                else
                        EMIT2(0x89, add_2reg(0xC0, dst, IA32_EDX));
        } else {
                if (dstk)
                        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
                              STACK_VAR(dst));
                else
                        EMIT2(0x89, add_2reg(0xC0, dst, IA32_EAX));
        }
        *pprog = prog;
}

/*
 * ALU operation (32 bit)
 * dst = dst (shift) src
 */
static inline void emit_ia32_shift_r(const u8 op, const u8 dst, const u8 src,
                                     bool dstk, bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg = dstk ? IA32_EAX : dst;
        u8 b2;

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(dst));

        if (sstk)
                /* mov ecx,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX), STACK_VAR(src));
        else if (src != IA32_ECX)
                /* mov ecx,src */
                EMIT2(0x8B, add_2reg(0xC0, src, IA32_ECX));

        switch (op) {
        case BPF_LSH:
                b2 = 0xE0; break;
        case BPF_RSH:
                b2 = 0xE8; break;
        case BPF_ARSH:
                b2 = 0xF8; break;
        default:
                return;
        }
        EMIT2(0xD3, add_1reg(b2, dreg));

        if (dstk)
                /* mov dword ptr [ebp+off],dreg */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg), STACK_VAR(dst));
        *pprog = prog;
}

/*
 * ALU operation (32 bit)
 * dst = dst (op) src
 */
static inline void emit_ia32_alu_r(const bool is64, const bool hi, const u8 op,
                                   const u8 dst, const u8 src, bool dstk,
                                   bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 sreg = sstk ? IA32_EAX : src;
        u8 dreg = dstk ? IA32_EDX : dst;

        if (sstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(src));

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX), STACK_VAR(dst));

        switch (BPF_OP(op)) {
        /* dst = dst + src */
        case BPF_ADD:
                if (hi && is64)
                        EMIT2(0x11, add_2reg(0xC0, dreg, sreg));
                else
                        EMIT2(0x01, add_2reg(0xC0, dreg, sreg));
                break;
        /* dst = dst - src */
        case BPF_SUB:
                if (hi && is64)
                        EMIT2(0x19, add_2reg(0xC0, dreg, sreg));
                else
                        EMIT2(0x29, add_2reg(0xC0, dreg, sreg));
                break;
        /* dst = dst | src */
        case BPF_OR:
                EMIT2(0x09, add_2reg(0xC0, dreg, sreg));
                break;
        /* dst = dst & src */
        case BPF_AND:
                EMIT2(0x21, add_2reg(0xC0, dreg, sreg));
                break;
        /* dst = dst ^ src */
        case BPF_XOR:
                EMIT2(0x31, add_2reg(0xC0, dreg, sreg));
                break;
        }

        if (dstk)
                /* mov dword ptr [ebp+off],dreg */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg),
                      STACK_VAR(dst));
        *pprog = prog;
}

/* ALU operation (64 bit) */
static inline void emit_ia32_alu_r64(const bool is64, const u8 op,
                                     const u8 dst[], const u8 src[],
                                     bool dstk,  bool sstk,
                                     u8 **pprog, const struct bpf_prog_aux *aux)
{
        u8 *prog = *pprog;

        emit_ia32_alu_r(is64, false, op, dst_lo, src_lo, dstk, sstk, &prog);
        if (is64)
                emit_ia32_alu_r(is64, true, op, dst_hi, src_hi, dstk, sstk,
                                &prog);
        else if (!aux->verifier_zext)
                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
        *pprog = prog;
}

/*
 * ALU operation (32 bit)
 * dst = dst (op) val
 */
static inline void emit_ia32_alu_i(const bool is64, const bool hi, const u8 op,
                                   const u8 dst, const s32 val, bool dstk,
                                   u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg = dstk ? IA32_EAX : dst;
        u8 sreg = IA32_EDX;

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(dst));

        if (!is_imm8(val))
                /* mov edx,imm32*/
                EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EDX), val);

        switch (op) {
        /* dst = dst + val */
        case BPF_ADD:
                if (hi && is64) {
                        if (is_imm8(val))
                                EMIT3(0x83, add_1reg(0xD0, dreg), val);
                        else
                                EMIT2(0x11, add_2reg(0xC0, dreg, sreg));
                } else {
                        if (is_imm8(val))
                                EMIT3(0x83, add_1reg(0xC0, dreg), val);
                        else
                                EMIT2(0x01, add_2reg(0xC0, dreg, sreg));
                }
                break;
        /* dst = dst - val */
        case BPF_SUB:
                if (hi && is64) {
                        if (is_imm8(val))
                                EMIT3(0x83, add_1reg(0xD8, dreg), val);
                        else
                                EMIT2(0x19, add_2reg(0xC0, dreg, sreg));
                } else {
                        if (is_imm8(val))
                                EMIT3(0x83, add_1reg(0xE8, dreg), val);
                        else
                                EMIT2(0x29, add_2reg(0xC0, dreg, sreg));
                }
                break;
        /* dst = dst | val */
        case BPF_OR:
                if (is_imm8(val))
                        EMIT3(0x83, add_1reg(0xC8, dreg), val);
                else
                        EMIT2(0x09, add_2reg(0xC0, dreg, sreg));
                break;
        /* dst = dst & val */
        case BPF_AND:
                if (is_imm8(val))
                        EMIT3(0x83, add_1reg(0xE0, dreg), val);
                else
                        EMIT2(0x21, add_2reg(0xC0, dreg, sreg));
                break;
        /* dst = dst ^ val */
        case BPF_XOR:
                if (is_imm8(val))
                        EMIT3(0x83, add_1reg(0xF0, dreg), val);
                else
                        EMIT2(0x31, add_2reg(0xC0, dreg, sreg));
                break;
        case BPF_NEG:
                EMIT2(0xF7, add_1reg(0xD8, dreg));
                break;
        }

        if (dstk)
                /* mov dword ptr [ebp+off],dreg */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg),
                      STACK_VAR(dst));
        *pprog = prog;
}

/* ALU operation (64 bit) */
static inline void emit_ia32_alu_i64(const bool is64, const u8 op,
                                     const u8 dst[], const u32 val,
                                     bool dstk, u8 **pprog,
                                     const struct bpf_prog_aux *aux)
{
        u8 *prog = *pprog;
        u32 hi = 0;

        if (is64 && (val & (1<<31)))
                hi = (u32)~0;

        emit_ia32_alu_i(is64, false, op, dst_lo, val, dstk, &prog);
        if (is64)
                emit_ia32_alu_i(is64, true, op, dst_hi, hi, dstk, &prog);
        else if (!aux->verifier_zext)
                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);

        *pprog = prog;
}

/* dst = ~dst (64 bit) */
static inline void emit_ia32_neg64(const u8 dst[], bool dstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }

        /* xor ecx,ecx */
        EMIT2(0x31, add_2reg(0xC0, IA32_ECX, IA32_ECX));
        /* sub dreg_lo,ecx */
        EMIT2(0x2B, add_2reg(0xC0, dreg_lo, IA32_ECX));
        /* mov dreg_lo,ecx */
        EMIT2(0x89, add_2reg(0xC0, dreg_lo, IA32_ECX));

        /* xor ecx,ecx */
        EMIT2(0x31, add_2reg(0xC0, IA32_ECX, IA32_ECX));
        /* sbb dreg_hi,ecx */
        EMIT2(0x19, add_2reg(0xC0, dreg_hi, IA32_ECX));
        /* mov dreg_hi,ecx */
        EMIT2(0x89, add_2reg(0xC0, dreg_hi, IA32_ECX));

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        *pprog = prog;
}

/* dst = dst << src */
static inline void emit_ia32_lsh_r64(const u8 dst[], const u8 src[],
                                     bool dstk, bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }

        if (sstk)
                /* mov ecx,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX),
                      STACK_VAR(src_lo));
        else
                /* mov ecx,src_lo */
                EMIT2(0x8B, add_2reg(0xC0, src_lo, IA32_ECX));

        /* shld dreg_hi,dreg_lo,cl */
        EMIT3(0x0F, 0xA5, add_2reg(0xC0, dreg_hi, dreg_lo));
        /* shl dreg_lo,cl */
        EMIT2(0xD3, add_1reg(0xE0, dreg_lo));

        /* if ecx >= 32, mov dreg_lo into dreg_hi and clear dreg_lo */

        /* cmp ecx,32 */
        EMIT3(0x83, add_1reg(0xF8, IA32_ECX), 32);
        /* skip the next two instructions (4 bytes) when < 32 */
        EMIT2(IA32_JB, 4);

        /* mov dreg_hi,dreg_lo */
        EMIT2(0x89, add_2reg(0xC0, dreg_hi, dreg_lo));
        /* xor dreg_lo,dreg_lo */
        EMIT2(0x33, add_2reg(0xC0, dreg_lo, dreg_lo));

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        /* out: */
        *pprog = prog;
}

/* dst = dst >> src (signed)*/
static inline void emit_ia32_arsh_r64(const u8 dst[], const u8 src[],
                                      bool dstk, bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }

        if (sstk)
                /* mov ecx,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX),
                      STACK_VAR(src_lo));
        else
                /* mov ecx,src_lo */
                EMIT2(0x8B, add_2reg(0xC0, src_lo, IA32_ECX));

        /* shrd dreg_lo,dreg_hi,cl */
        EMIT3(0x0F, 0xAD, add_2reg(0xC0, dreg_lo, dreg_hi));
        /* sar dreg_hi,cl */
        EMIT2(0xD3, add_1reg(0xF8, dreg_hi));

        /* if ecx >= 32, mov dreg_hi to dreg_lo and set/clear dreg_hi depending on sign */

        /* cmp ecx,32 */
        EMIT3(0x83, add_1reg(0xF8, IA32_ECX), 32);
        /* skip the next two instructions (5 bytes) when < 32 */
        EMIT2(IA32_JB, 5);

        /* mov dreg_lo,dreg_hi */
        EMIT2(0x89, add_2reg(0xC0, dreg_lo, dreg_hi));
        /* sar dreg_hi,31 */
        EMIT3(0xC1, add_1reg(0xF8, dreg_hi), 31);

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        /* out: */
        *pprog = prog;
}

/* dst = dst >> src */
static inline void emit_ia32_rsh_r64(const u8 dst[], const u8 src[], bool dstk,
                                     bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }

        if (sstk)
                /* mov ecx,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX),
                      STACK_VAR(src_lo));
        else
                /* mov ecx,src_lo */
                EMIT2(0x8B, add_2reg(0xC0, src_lo, IA32_ECX));

        /* shrd dreg_lo,dreg_hi,cl */
        EMIT3(0x0F, 0xAD, add_2reg(0xC0, dreg_lo, dreg_hi));
        /* shr dreg_hi,cl */
        EMIT2(0xD3, add_1reg(0xE8, dreg_hi));

        /* if ecx >= 32, mov dreg_hi to dreg_lo and clear dreg_hi */

        /* cmp ecx,32 */
        EMIT3(0x83, add_1reg(0xF8, IA32_ECX), 32);
        /* skip the next two instructions (4 bytes) when < 32 */
        EMIT2(IA32_JB, 4);

        /* mov dreg_lo,dreg_hi */
        EMIT2(0x89, add_2reg(0xC0, dreg_lo, dreg_hi));
        /* xor dreg_hi,dreg_hi */
        EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        /* out: */
        *pprog = prog;
}

/* dst = dst << val */
static inline void emit_ia32_lsh_i64(const u8 dst[], const u32 val,
                                     bool dstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }
        /* Do LSH operation */
        if (val < 32) {
                /* shld dreg_hi,dreg_lo,imm8 */
                EMIT4(0x0F, 0xA4, add_2reg(0xC0, dreg_hi, dreg_lo), val);
                /* shl dreg_lo,imm8 */
                EMIT3(0xC1, add_1reg(0xE0, dreg_lo), val);
        } else if (val >= 32 && val < 64) {
                u32 value = val - 32;

                /* shl dreg_lo,imm8 */
                EMIT3(0xC1, add_1reg(0xE0, dreg_lo), value);
                /* mov dreg_hi,dreg_lo */
                EMIT2(0x89, add_2reg(0xC0, dreg_hi, dreg_lo));
                /* xor dreg_lo,dreg_lo */
                EMIT2(0x33, add_2reg(0xC0, dreg_lo, dreg_lo));
        } else {
                /* xor dreg_lo,dreg_lo */
                EMIT2(0x33, add_2reg(0xC0, dreg_lo, dreg_lo));
                /* xor dreg_hi,dreg_hi */
                EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
        }

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        *pprog = prog;
}

/* dst = dst >> val */
static inline void emit_ia32_rsh_i64(const u8 dst[], const u32 val,
                                     bool dstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }

        /* Do RSH operation */
        if (val < 32) {
                /* shrd dreg_lo,dreg_hi,imm8 */
                EMIT4(0x0F, 0xAC, add_2reg(0xC0, dreg_lo, dreg_hi), val);
                /* shr dreg_hi,imm8 */
                EMIT3(0xC1, add_1reg(0xE8, dreg_hi), val);
        } else if (val >= 32 && val < 64) {
                u32 value = val - 32;

                /* shr dreg_hi,imm8 */
                EMIT3(0xC1, add_1reg(0xE8, dreg_hi), value);
                /* mov dreg_lo,dreg_hi */
                EMIT2(0x89, add_2reg(0xC0, dreg_lo, dreg_hi));
                /* xor dreg_hi,dreg_hi */
                EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
        } else {
                /* xor dreg_lo,dreg_lo */
                EMIT2(0x33, add_2reg(0xC0, dreg_lo, dreg_lo));
                /* xor dreg_hi,dreg_hi */
                EMIT2(0x33, add_2reg(0xC0, dreg_hi, dreg_hi));
        }

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        *pprog = prog;
}

/* dst = dst >> val (signed) */
static inline void emit_ia32_arsh_i64(const u8 dst[], const u32 val,
                                      bool dstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;

        if (dstk) {
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),

                      STACK_VAR(dst_lo));
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                      STACK_VAR(dst_hi));
        }
        /* Do RSH operation */
        if (val < 32) {
                /* shrd dreg_lo,dreg_hi,imm8 */
                EMIT4(0x0F, 0xAC, add_2reg(0xC0, dreg_lo, dreg_hi), val);
                /* ashr dreg_hi,imm8 */
                EMIT3(0xC1, add_1reg(0xF8, dreg_hi), val);
        } else if (val >= 32 && val < 64) {
                u32 value = val - 32;

                /* ashr dreg_hi,imm8 */
                EMIT3(0xC1, add_1reg(0xF8, dreg_hi), value);
                /* mov dreg_lo,dreg_hi */
                EMIT2(0x89, add_2reg(0xC0, dreg_lo, dreg_hi));

                /* ashr dreg_hi,imm8 */
                EMIT3(0xC1, add_1reg(0xF8, dreg_hi), 31);
        } else {
                /* ashr dreg_hi,imm8 */
                EMIT3(0xC1, add_1reg(0xF8, dreg_hi), 31);
                /* mov dreg_lo,dreg_hi */
                EMIT2(0x89, add_2reg(0xC0, dreg_lo, dreg_hi));
        }

        if (dstk) {
                /* mov dword ptr [ebp+off],dreg_lo */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_lo),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],dreg_hi */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, dreg_hi),
                      STACK_VAR(dst_hi));
        }
        *pprog = prog;
}

static inline void emit_ia32_mul_r64(const u8 dst[], const u8 src[], bool dstk,
                                     bool sstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_hi));
        else
                /* mov eax,dst_hi */
                EMIT2(0x8B, add_2reg(0xC0, dst_hi, IA32_EAX));

        if (sstk)
                /* mul dword ptr [ebp+off] */
                EMIT3(0xF7, add_1reg(0x60, IA32_EBP), STACK_VAR(src_lo));
        else
                /* mul src_lo */
                EMIT2(0xF7, add_1reg(0xE0, src_lo));

        /* mov ecx,eax */
        EMIT2(0x89, add_2reg(0xC0, IA32_ECX, IA32_EAX));

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
        else
                /* mov eax,dst_lo */
                EMIT2(0x8B, add_2reg(0xC0, dst_lo, IA32_EAX));

        if (sstk)
                /* mul dword ptr [ebp+off] */
                EMIT3(0xF7, add_1reg(0x60, IA32_EBP), STACK_VAR(src_hi));
        else
                /* mul src_hi */
                EMIT2(0xF7, add_1reg(0xE0, src_hi));

        /* add eax,eax */
        EMIT2(0x01, add_2reg(0xC0, IA32_ECX, IA32_EAX));

        if (dstk)
                /* mov eax,dword ptr [ebp+off] */
                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
        else
                /* mov eax,dst_lo */
                EMIT2(0x8B, add_2reg(0xC0, dst_lo, IA32_EAX));

        if (sstk)
                /* mul dword ptr [ebp+off] */
                EMIT3(0xF7, add_1reg(0x60, IA32_EBP), STACK_VAR(src_lo));
        else
                /* mul src_lo */
                EMIT2(0xF7, add_1reg(0xE0, src_lo));

        /* add ecx,edx */
        EMIT2(0x01, add_2reg(0xC0, IA32_ECX, IA32_EDX));

        if (dstk) {
                /* mov dword ptr [ebp+off],eax */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],ecx */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_ECX),
                      STACK_VAR(dst_hi));
        } else {
                /* mov dst_lo,eax */
                EMIT2(0x89, add_2reg(0xC0, dst_lo, IA32_EAX));
                /* mov dst_hi,ecx */
                EMIT2(0x89, add_2reg(0xC0, dst_hi, IA32_ECX));
        }

        *pprog = prog;
}

static inline void emit_ia32_mul_i64(const u8 dst[], const u32 val,
                                     bool dstk, u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        u32 hi;

        hi = val & (1<<31) ? (u32)~0 : 0;
        /* movl eax,imm32 */
        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EAX), val);
        if (dstk)
                /* mul dword ptr [ebp+off] */
                EMIT3(0xF7, add_1reg(0x60, IA32_EBP), STACK_VAR(dst_hi));
        else
                /* mul dst_hi */
                EMIT2(0xF7, add_1reg(0xE0, dst_hi));

        /* mov ecx,eax */
        EMIT2(0x89, add_2reg(0xC0, IA32_ECX, IA32_EAX));

        /* movl eax,imm32 */
        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EAX), hi);
        if (dstk)
                /* mul dword ptr [ebp+off] */
                EMIT3(0xF7, add_1reg(0x60, IA32_EBP), STACK_VAR(dst_lo));
        else
                /* mul dst_lo */
                EMIT2(0xF7, add_1reg(0xE0, dst_lo));
        /* add ecx,eax */
        EMIT2(0x01, add_2reg(0xC0, IA32_ECX, IA32_EAX));

        /* movl eax,imm32 */
        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EAX), val);
        if (dstk)
                /* mul dword ptr [ebp+off] */
                EMIT3(0xF7, add_1reg(0x60, IA32_EBP), STACK_VAR(dst_lo));
        else
                /* mul dst_lo */
                EMIT2(0xF7, add_1reg(0xE0, dst_lo));

        /* add ecx,edx */
        EMIT2(0x01, add_2reg(0xC0, IA32_ECX, IA32_EDX));

        if (dstk) {
                /* mov dword ptr [ebp+off],eax */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
                      STACK_VAR(dst_lo));
                /* mov dword ptr [ebp+off],ecx */
                EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_ECX),
                      STACK_VAR(dst_hi));
        } else {
                /* mov dword ptr [ebp+off],eax */
                EMIT2(0x89, add_2reg(0xC0, dst_lo, IA32_EAX));
                /* mov dword ptr [ebp+off],ecx */
                EMIT2(0x89, add_2reg(0xC0, dst_hi, IA32_ECX));
        }

        *pprog = prog;
}

static int bpf_size_to_x86_bytes(int bpf_size)
{
        if (bpf_size == BPF_W)
                return 4;
        else if (bpf_size == BPF_H)
                return 2;
        else if (bpf_size == BPF_B)
                return 1;
        else if (bpf_size == BPF_DW)
                return 4; /* imm32 */
        else
                return 0;
}

struct jit_context {
        int cleanup_addr; /* Epilogue code offset */
};

/* Maximum number of bytes emitted while JITing one eBPF insn */
#define BPF_MAX_INSN_SIZE       128
#define BPF_INSN_SAFETY         64

#define PROLOGUE_SIZE 35

/*
 * Emit prologue code for BPF program and check it's size.
 * bpf_tail_call helper will skip it while jumping into another program.
 */
static void emit_prologue(u8 **pprog, u32 stack_depth)
{
        u8 *prog = *pprog;
        int cnt = 0;
        const u8 *r1 = bpf2ia32[BPF_REG_1];
        const u8 fplo = bpf2ia32[BPF_REG_FP][0];
        const u8 fphi = bpf2ia32[BPF_REG_FP][1];
        const u8 *tcc = bpf2ia32[TCALL_CNT];

        /* push ebp */
        EMIT1(0x55);
        /* mov ebp,esp */
        EMIT2(0x89, 0xE5);
        /* push edi */
        EMIT1(0x57);
        /* push esi */
        EMIT1(0x56);
        /* push ebx */
        EMIT1(0x53);

        /* sub esp,STACK_SIZE */
        EMIT2_off32(0x81, 0xEC, STACK_SIZE);
        /* sub ebp,SCRATCH_SIZE+12*/
        EMIT3(0x83, add_1reg(0xE8, IA32_EBP), SCRATCH_SIZE + 12);
        /* xor ebx,ebx */
        EMIT2(0x31, add_2reg(0xC0, IA32_EBX, IA32_EBX));

        /* Set up BPF prog stack base register */
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EBP), STACK_VAR(fplo));
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EBX), STACK_VAR(fphi));

        /* Move BPF_CTX (EAX) to BPF_REG_R1 */
        /* mov dword ptr [ebp+off],eax */
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(r1[0]));
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EBX), STACK_VAR(r1[1]));

        /* Initialize Tail Count */
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EBX), STACK_VAR(tcc[0]));
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EBX), STACK_VAR(tcc[1]));

        BUILD_BUG_ON(cnt != PROLOGUE_SIZE);
        *pprog = prog;
}

/* Emit epilogue code for BPF program */
static void emit_epilogue(u8 **pprog, u32 stack_depth)
{
        u8 *prog = *pprog;
        const u8 *r0 = bpf2ia32[BPF_REG_0];
        int cnt = 0;

        /* mov eax,dword ptr [ebp+off]*/
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(r0[0]));
        /* mov edx,dword ptr [ebp+off]*/
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX), STACK_VAR(r0[1]));

        /* add ebp,SCRATCH_SIZE+12*/
        EMIT3(0x83, add_1reg(0xC0, IA32_EBP), SCRATCH_SIZE + 12);

        /* mov ebx,dword ptr [ebp-12]*/
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EBX), -12);
        /* mov esi,dword ptr [ebp-8]*/
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ESI), -8);
        /* mov edi,dword ptr [ebp-4]*/
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDI), -4);

        EMIT1(0xC9); /* leave */
        EMIT1(0xC3); /* ret */
        *pprog = prog;
}

/*
 * Generate the following code:
 * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
 *   if (index >= array->map.max_entries)
 *     goto out;
 *   if (++tail_call_cnt > MAX_TAIL_CALL_CNT)
 *     goto out;
 *   prog = array->ptrs[index];
 *   if (prog == NULL)
 *     goto out;
 *   goto *(prog->bpf_func + prologue_size);
 * out:
 */
static void emit_bpf_tail_call(u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;
        const u8 *r1 = bpf2ia32[BPF_REG_1];
        const u8 *r2 = bpf2ia32[BPF_REG_2];
        const u8 *r3 = bpf2ia32[BPF_REG_3];
        const u8 *tcc = bpf2ia32[TCALL_CNT];
        u32 lo, hi;
        static int jmp_label1 = -1;

        /*
         * if (index >= array->map.max_entries)
         *     goto out;
         */
        /* mov eax,dword ptr [ebp+off] */
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(r2[0]));
        /* mov edx,dword ptr [ebp+off] */
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX), STACK_VAR(r3[0]));

        /* cmp dword ptr [eax+off],edx */
        EMIT3(0x39, add_2reg(0x40, IA32_EAX, IA32_EDX),
              offsetof(struct bpf_array, map.max_entries));
        /* jbe out */
        EMIT2(IA32_JBE, jmp_label(jmp_label1, 2));

        /*
         * if (tail_call_cnt > MAX_TAIL_CALL_CNT)
         *     goto out;
         */
        lo = (u32)MAX_TAIL_CALL_CNT;
        hi = (u32)((u64)MAX_TAIL_CALL_CNT >> 32);
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX), STACK_VAR(tcc[0]));
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EBX), STACK_VAR(tcc[1]));

        /* cmp edx,hi */
        EMIT3(0x83, add_1reg(0xF8, IA32_EBX), hi);
        EMIT2(IA32_JNE, 3);
        /* cmp ecx,lo */
        EMIT3(0x83, add_1reg(0xF8, IA32_ECX), lo);

        /* ja out */
        EMIT2(IA32_JAE, jmp_label(jmp_label1, 2));

        /* add eax,0x1 */
        EMIT3(0x83, add_1reg(0xC0, IA32_ECX), 0x01);
        /* adc ebx,0x0 */
        EMIT3(0x83, add_1reg(0xD0, IA32_EBX), 0x00);

        /* mov dword ptr [ebp+off],eax */
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_ECX), STACK_VAR(tcc[0]));
        /* mov dword ptr [ebp+off],edx */
        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EBX), STACK_VAR(tcc[1]));

        /* prog = array->ptrs[index]; */
        /* mov edx, [eax + edx * 4 + offsetof(...)] */
        EMIT3_off32(0x8B, 0x94, 0x90, offsetof(struct bpf_array, ptrs));

        /*
         * if (prog == NULL)
         *     goto out;
         */
        /* test edx,edx */
        EMIT2(0x85, add_2reg(0xC0, IA32_EDX, IA32_EDX));
        /* je out */
        EMIT2(IA32_JE, jmp_label(jmp_label1, 2));

        /* goto *(prog->bpf_func + prologue_size); */
        /* mov edx, dword ptr [edx + 32] */
        EMIT3(0x8B, add_2reg(0x40, IA32_EDX, IA32_EDX),
              offsetof(struct bpf_prog, bpf_func));
        /* add edx,prologue_size */
        EMIT3(0x83, add_1reg(0xC0, IA32_EDX), PROLOGUE_SIZE);

        /* mov eax,dword ptr [ebp+off] */
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX), STACK_VAR(r1[0]));

        /*
         * Now we're ready to jump into next BPF program:
         * eax == ctx (1st arg)
         * edx == prog->bpf_func + prologue_size
         */
        RETPOLINE_EDX_BPF_JIT();

        if (jmp_label1 == -1)
                jmp_label1 = cnt;

        /* out: */
        *pprog = prog;
}

/* Push the scratch stack register on top of the stack. */
static inline void emit_push_r64(const u8 src[], u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;

        /* mov ecx,dword ptr [ebp+off] */
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX), STACK_VAR(src_hi));
        /* push ecx */
        EMIT1(0x51);

        /* mov ecx,dword ptr [ebp+off] */
        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX), STACK_VAR(src_lo));
        /* push ecx */
        EMIT1(0x51);

        *pprog = prog;
}

static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
                  int oldproglen, struct jit_context *ctx)
{
        struct bpf_insn *insn = bpf_prog->insnsi;
        int insn_cnt = bpf_prog->len;
        bool seen_exit = false;
        u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY];
        int i, cnt = 0;
        int proglen = 0;
        u8 *prog = temp;

        emit_prologue(&prog, bpf_prog->aux->stack_depth);

        for (i = 0; i < insn_cnt; i++, insn++) {
                const s32 imm32 = insn->imm;
                const bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
                const bool dstk = insn->dst_reg == BPF_REG_AX ? false : true;
                const bool sstk = insn->src_reg == BPF_REG_AX ? false : true;
                const u8 code = insn->code;
                const u8 *dst = bpf2ia32[insn->dst_reg];
                const u8 *src = bpf2ia32[insn->src_reg];
                const u8 *r0 = bpf2ia32[BPF_REG_0];
                s64 jmp_offset;
                u8 jmp_cond;
                int ilen;
                u8 *func;

                switch (code) {
                /* ALU operations */
                /* dst = src */
                case BPF_ALU | BPF_MOV | BPF_K:
                case BPF_ALU | BPF_MOV | BPF_X:
                case BPF_ALU64 | BPF_MOV | BPF_K:
                case BPF_ALU64 | BPF_MOV | BPF_X:
                        switch (BPF_SRC(code)) {
                        case BPF_X:
                                if (imm32 == 1) {
                                        /* Special mov32 for zext. */
                                        emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
                                        break;
                                }
                                emit_ia32_mov_r64(is64, dst, src, dstk, sstk,
                                                  &prog, bpf_prog->aux);
                                break;
                        case BPF_K:
                                /* Sign-extend immediate value to dst reg */
                                emit_ia32_mov_i64(is64, dst, imm32,
                                                  dstk, &prog);
                                break;
                        }
                        break;
                /* dst = dst + src/imm */
                /* dst = dst - src/imm */
                /* dst = dst | src/imm */
                /* dst = dst & src/imm */
                /* dst = dst ^ src/imm */
                /* dst = dst * src/imm */
                /* dst = dst << src */
                /* dst = dst >> src */
                case BPF_ALU | BPF_ADD | BPF_K:
                case BPF_ALU | BPF_ADD | BPF_X:
                case BPF_ALU | BPF_SUB | BPF_K:
                case BPF_ALU | BPF_SUB | BPF_X:
                case BPF_ALU | BPF_OR | BPF_K:
                case BPF_ALU | BPF_OR | BPF_X:
                case BPF_ALU | BPF_AND | BPF_K:
                case BPF_ALU | BPF_AND | BPF_X:
                case BPF_ALU | BPF_XOR | BPF_K:
                case BPF_ALU | BPF_XOR | BPF_X:
                case BPF_ALU64 | BPF_ADD | BPF_K:
                case BPF_ALU64 | BPF_ADD | BPF_X:
                case BPF_ALU64 | BPF_SUB | BPF_K:
                case BPF_ALU64 | BPF_SUB | BPF_X:
                case BPF_ALU64 | BPF_OR | BPF_K:
                case BPF_ALU64 | BPF_OR | BPF_X:
                case BPF_ALU64 | BPF_AND | BPF_K:
                case BPF_ALU64 | BPF_AND | BPF_X:
                case BPF_ALU64 | BPF_XOR | BPF_K:
                case BPF_ALU64 | BPF_XOR | BPF_X:
                        switch (BPF_SRC(code)) {
                        case BPF_X:
                                emit_ia32_alu_r64(is64, BPF_OP(code), dst,
                                                  src, dstk, sstk, &prog,
                                                  bpf_prog->aux);
                                break;
                        case BPF_K:
                                emit_ia32_alu_i64(is64, BPF_OP(code), dst,
                                                  imm32, dstk, &prog,
                                                  bpf_prog->aux);
                                break;
                        }
                        break;
                case BPF_ALU | BPF_MUL | BPF_K:
                case BPF_ALU | BPF_MUL | BPF_X:
                        switch (BPF_SRC(code)) {
                        case BPF_X:
                                emit_ia32_mul_r(dst_lo, src_lo, dstk,
                                                sstk, &prog);
                                break;
                        case BPF_K:
                                /* mov ecx,imm32*/
                                EMIT2_off32(0xC7, add_1reg(0xC0, IA32_ECX),
                                            imm32);
                                emit_ia32_mul_r(dst_lo, IA32_ECX, dstk,
                                                false, &prog);
                                break;
                        }
                        if (!bpf_prog->aux->verifier_zext)
                                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
                        break;
                case BPF_ALU | BPF_LSH | BPF_X:
                case BPF_ALU | BPF_RSH | BPF_X:
                case BPF_ALU | BPF_ARSH | BPF_K:
                case BPF_ALU | BPF_ARSH | BPF_X:
                        switch (BPF_SRC(code)) {
                        case BPF_X:
                                emit_ia32_shift_r(BPF_OP(code), dst_lo, src_lo,
                                                  dstk, sstk, &prog);
                                break;
                        case BPF_K:
                                /* mov ecx,imm32*/
                                EMIT2_off32(0xC7, add_1reg(0xC0, IA32_ECX),
                                            imm32);
                                emit_ia32_shift_r(BPF_OP(code), dst_lo,
                                                  IA32_ECX, dstk, false,
                                                  &prog);
                                break;
                        }
                        if (!bpf_prog->aux->verifier_zext)
                                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
                        break;
                /* dst = dst / src(imm) */
                /* dst = dst % src(imm) */
                case BPF_ALU | BPF_DIV | BPF_K:
                case BPF_ALU | BPF_DIV | BPF_X:
                case BPF_ALU | BPF_MOD | BPF_K:
                case BPF_ALU | BPF_MOD | BPF_X:
                        switch (BPF_SRC(code)) {
                        case BPF_X:
                                emit_ia32_div_mod_r(BPF_OP(code), dst_lo,
                                                    src_lo, dstk, sstk, &prog);
                                break;
                        case BPF_K:
                                /* mov ecx,imm32*/
                                EMIT2_off32(0xC7, add_1reg(0xC0, IA32_ECX),
                                            imm32);
                                emit_ia32_div_mod_r(BPF_OP(code), dst_lo,
                                                    IA32_ECX, dstk, false,
                                                    &prog);
                                break;
                        }
                        if (!bpf_prog->aux->verifier_zext)
                                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
                        break;
                case BPF_ALU64 | BPF_DIV | BPF_K:
                case BPF_ALU64 | BPF_DIV | BPF_X:
                case BPF_ALU64 | BPF_MOD | BPF_K:
                case BPF_ALU64 | BPF_MOD | BPF_X:
                        goto notyet;
                /* dst = dst >> imm */
                /* dst = dst << imm */
                case BPF_ALU | BPF_RSH | BPF_K:
                case BPF_ALU | BPF_LSH | BPF_K:
                        if (unlikely(imm32 > 31))
                                return -EINVAL;
                        /* mov ecx,imm32*/
                        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_ECX), imm32);
                        emit_ia32_shift_r(BPF_OP(code), dst_lo, IA32_ECX, dstk,
                                          false, &prog);
                        if (!bpf_prog->aux->verifier_zext)
                                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
                        break;
                /* dst = dst << imm */
                case BPF_ALU64 | BPF_LSH | BPF_K:
                        if (unlikely(imm32 > 63))
                                return -EINVAL;
                        emit_ia32_lsh_i64(dst, imm32, dstk, &prog);
                        break;
                /* dst = dst >> imm */
                case BPF_ALU64 | BPF_RSH | BPF_K:
                        if (unlikely(imm32 > 63))
                                return -EINVAL;
                        emit_ia32_rsh_i64(dst, imm32, dstk, &prog);
                        break;
                /* dst = dst << src */
                case BPF_ALU64 | BPF_LSH | BPF_X:
                        emit_ia32_lsh_r64(dst, src, dstk, sstk, &prog);
                        break;
                /* dst = dst >> src */
                case BPF_ALU64 | BPF_RSH | BPF_X:
                        emit_ia32_rsh_r64(dst, src, dstk, sstk, &prog);
                        break;
                /* dst = dst >> src (signed) */
                case BPF_ALU64 | BPF_ARSH | BPF_X:
                        emit_ia32_arsh_r64(dst, src, dstk, sstk, &prog);
                        break;
                /* dst = dst >> imm (signed) */
                case BPF_ALU64 | BPF_ARSH | BPF_K:
                        if (unlikely(imm32 > 63))
                                return -EINVAL;
                        emit_ia32_arsh_i64(dst, imm32, dstk, &prog);
                        break;
                /* dst = ~dst */
                case BPF_ALU | BPF_NEG:
                        emit_ia32_alu_i(is64, false, BPF_OP(code),
                                        dst_lo, 0, dstk, &prog);
                        if (!bpf_prog->aux->verifier_zext)
                                emit_ia32_mov_i(dst_hi, 0, dstk, &prog);
                        break;
                /* dst = ~dst (64 bit) */
                case BPF_ALU64 | BPF_NEG:
                        emit_ia32_neg64(dst, dstk, &prog);
                        break;
                /* dst = dst * src/imm */
                case BPF_ALU64 | BPF_MUL | BPF_X:
                case BPF_ALU64 | BPF_MUL | BPF_K:
                        switch (BPF_SRC(code)) {
                        case BPF_X:
                                emit_ia32_mul_r64(dst, src, dstk, sstk, &prog);
                                break;
                        case BPF_K:
                                emit_ia32_mul_i64(dst, imm32, dstk, &prog);
                                break;
                        }
                        break;
                /* dst = htole(dst) */
                case BPF_ALU | BPF_END | BPF_FROM_LE:
                        emit_ia32_to_le_r64(dst, imm32, dstk, &prog,
                                            bpf_prog->aux);
                        break;
                /* dst = htobe(dst) */
                case BPF_ALU | BPF_END | BPF_FROM_BE:
                        emit_ia32_to_be_r64(dst, imm32, dstk, &prog,
                                            bpf_prog->aux);
                        break;
                /* dst = imm64 */
                case BPF_LD | BPF_IMM | BPF_DW: {
                        s32 hi, lo = imm32;

                        hi = insn[1].imm;
                        emit_ia32_mov_i(dst_lo, lo, dstk, &prog);
                        emit_ia32_mov_i(dst_hi, hi, dstk, &prog);
                        insn++;
                        i++;
                        break;
                }
                /* ST: *(u8*)(dst_reg + off) = imm */
                case BPF_ST | BPF_MEM | BPF_H:
                case BPF_ST | BPF_MEM | BPF_B:
                case BPF_ST | BPF_MEM | BPF_W:
                case BPF_ST | BPF_MEM | BPF_DW:
                        if (dstk)
                                /* mov eax,dword ptr [ebp+off] */
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(dst_lo));
                        else
                                /* mov eax,dst_lo */
                                EMIT2(0x8B, add_2reg(0xC0, dst_lo, IA32_EAX));

                        switch (BPF_SIZE(code)) {
                        case BPF_B:
                                EMIT(0xC6, 1); break;
                        case BPF_H:
                                EMIT2(0x66, 0xC7); break;
                        case BPF_W:
                        case BPF_DW:
                                EMIT(0xC7, 1); break;
                        }

                        if (is_imm8(insn->off))
                                EMIT2(add_1reg(0x40, IA32_EAX), insn->off);
                        else
                                EMIT1_off32(add_1reg(0x80, IA32_EAX),
                                            insn->off);
                        EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(code)));

                        if (BPF_SIZE(code) == BPF_DW) {
                                u32 hi;

                                hi = imm32 & (1<<31) ? (u32)~0 : 0;
                                EMIT2_off32(0xC7, add_1reg(0x80, IA32_EAX),
                                            insn->off + 4);
                                EMIT(hi, 4);
                        }
                        break;

                /* STX: *(u8*)(dst_reg + off) = src_reg */
                case BPF_STX | BPF_MEM | BPF_B:
                case BPF_STX | BPF_MEM | BPF_H:
                case BPF_STX | BPF_MEM | BPF_W:
                case BPF_STX | BPF_MEM | BPF_DW:
                        if (dstk)
                                /* mov eax,dword ptr [ebp+off] */
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(dst_lo));
                        else
                                /* mov eax,dst_lo */
                                EMIT2(0x8B, add_2reg(0xC0, dst_lo, IA32_EAX));

                        if (sstk)
                                /* mov edx,dword ptr [ebp+off] */
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                                      STACK_VAR(src_lo));
                        else
                                /* mov edx,src_lo */
                                EMIT2(0x8B, add_2reg(0xC0, src_lo, IA32_EDX));

                        switch (BPF_SIZE(code)) {
                        case BPF_B:
                                EMIT(0x88, 1); break;
                        case BPF_H:
                                EMIT2(0x66, 0x89); break;
                        case BPF_W:
                        case BPF_DW:
                                EMIT(0x89, 1); break;
                        }

                        if (is_imm8(insn->off))
                                EMIT2(add_2reg(0x40, IA32_EAX, IA32_EDX),
                                      insn->off);
                        else
                                EMIT1_off32(add_2reg(0x80, IA32_EAX, IA32_EDX),
                                            insn->off);

                        if (BPF_SIZE(code) == BPF_DW) {
                                if (sstk)
                                        /* mov edi,dword ptr [ebp+off] */
                                        EMIT3(0x8B, add_2reg(0x40, IA32_EBP,
                                                             IA32_EDX),
                                              STACK_VAR(src_hi));
                                else
                                        /* mov edi,src_hi */
                                        EMIT2(0x8B, add_2reg(0xC0, src_hi,
                                                             IA32_EDX));
                                EMIT1(0x89);
                                if (is_imm8(insn->off + 4)) {
                                        EMIT2(add_2reg(0x40, IA32_EAX,
                                                       IA32_EDX),
                                              insn->off + 4);
                                } else {
                                        EMIT1(add_2reg(0x80, IA32_EAX,
                                                       IA32_EDX));
                                        EMIT(insn->off + 4, 4);
                                }
                        }
                        break;

                /* LDX: dst_reg = *(u8*)(src_reg + off) */
                case BPF_LDX | BPF_MEM | BPF_B:
                case BPF_LDX | BPF_MEM | BPF_H:
                case BPF_LDX | BPF_MEM | BPF_W:
                case BPF_LDX | BPF_MEM | BPF_DW:
                        if (sstk)
                                /* mov eax,dword ptr [ebp+off] */
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(src_lo));
                        else
                                /* mov eax,dword ptr [ebp+off] */
                                EMIT2(0x8B, add_2reg(0xC0, src_lo, IA32_EAX));

                        switch (BPF_SIZE(code)) {
                        case BPF_B:
                                EMIT2(0x0F, 0xB6); break;
                        case BPF_H:
                                EMIT2(0x0F, 0xB7); break;
                        case BPF_W:
                        case BPF_DW:
                                EMIT(0x8B, 1); break;
                        }

                        if (is_imm8(insn->off))
                                EMIT2(add_2reg(0x40, IA32_EAX, IA32_EDX),
                                      insn->off);
                        else
                                EMIT1_off32(add_2reg(0x80, IA32_EAX, IA32_EDX),
                                            insn->off);

                        if (dstk)
                                /* mov dword ptr [ebp+off],edx */
                                EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EDX),
                                      STACK_VAR(dst_lo));
                        else
                                /* mov dst_lo,edx */
                                EMIT2(0x89, add_2reg(0xC0, dst_lo, IA32_EDX));
                        switch (BPF_SIZE(code)) {
                        case BPF_B:
                        case BPF_H:
                        case BPF_W:
                                if (!bpf_prog->aux->verifier_zext)
                                        break;
                                if (dstk) {
                                        EMIT3(0xC7, add_1reg(0x40, IA32_EBP),
                                              STACK_VAR(dst_hi));
                                        EMIT(0x0, 4);
                                } else {
                                        EMIT3(0xC7, add_1reg(0xC0, dst_hi), 0);
                                }
                                break;
                        case BPF_DW:
                                EMIT2_off32(0x8B,
                                            add_2reg(0x80, IA32_EAX, IA32_EDX),
                                            insn->off + 4);
                                if (dstk)
                                        EMIT3(0x89,
                                              add_2reg(0x40, IA32_EBP,
                                                       IA32_EDX),
                                              STACK_VAR(dst_hi));
                                else
                                        EMIT2(0x89,
                                              add_2reg(0xC0, dst_hi, IA32_EDX));
                                break;
                        default:
                                break;
                        }
                        break;
                /* call */
                case BPF_JMP | BPF_CALL:
                {
                        const u8 *r1 = bpf2ia32[BPF_REG_1];
                        const u8 *r2 = bpf2ia32[BPF_REG_2];
                        const u8 *r3 = bpf2ia32[BPF_REG_3];
                        const u8 *r4 = bpf2ia32[BPF_REG_4];
                        const u8 *r5 = bpf2ia32[BPF_REG_5];

                        if (insn->src_reg == BPF_PSEUDO_CALL)
                                goto notyet;

                        func = (u8 *) __bpf_call_base + imm32;
                        jmp_offset = func - (image + addrs[i]);

                        if (!imm32 || !is_simm32(jmp_offset)) {
                                pr_err("unsupported BPF func %d addr %p image %p\n",
                                       imm32, func, image);
                                return -EINVAL;
                        }

                        /* mov eax,dword ptr [ebp+off] */
                        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                              STACK_VAR(r1[0]));
                        /* mov edx,dword ptr [ebp+off] */
                        EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                              STACK_VAR(r1[1]));

                        emit_push_r64(r5, &prog);
                        emit_push_r64(r4, &prog);
                        emit_push_r64(r3, &prog);
                        emit_push_r64(r2, &prog);

                        EMIT1_off32(0xE8, jmp_offset + 9);

                        /* mov dword ptr [ebp+off],eax */
                        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EAX),
                              STACK_VAR(r0[0]));
                        /* mov dword ptr [ebp+off],edx */
                        EMIT3(0x89, add_2reg(0x40, IA32_EBP, IA32_EDX),
                              STACK_VAR(r0[1]));

                        /* add esp,32 */
                        EMIT3(0x83, add_1reg(0xC0, IA32_ESP), 32);
                        break;
                }
                case BPF_JMP | BPF_TAIL_CALL:
                        emit_bpf_tail_call(&prog);
                        break;

                /* cond jump */
                case BPF_JMP | BPF_JEQ | BPF_X:
                case BPF_JMP | BPF_JNE | BPF_X:
                case BPF_JMP | BPF_JGT | BPF_X:
                case BPF_JMP | BPF_JLT | BPF_X:
                case BPF_JMP | BPF_JGE | BPF_X:
                case BPF_JMP | BPF_JLE | BPF_X:
                case BPF_JMP | BPF_JSGT | BPF_X:
                case BPF_JMP | BPF_JSLE | BPF_X:
                case BPF_JMP | BPF_JSLT | BPF_X:
                case BPF_JMP | BPF_JSGE | BPF_X: {
                        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
                        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;
                        u8 sreg_lo = sstk ? IA32_ECX : src_lo;
                        u8 sreg_hi = sstk ? IA32_EBX : src_hi;

                        if (dstk) {
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(dst_lo));
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                                      STACK_VAR(dst_hi));
                        }

                        if (sstk) {
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX),
                                      STACK_VAR(src_lo));
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EBX),
                                      STACK_VAR(src_hi));
                        }

                        /* cmp dreg_hi,sreg_hi */
                        EMIT2(0x39, add_2reg(0xC0, dreg_hi, sreg_hi));
                        EMIT2(IA32_JNE, 2);
                        /* cmp dreg_lo,sreg_lo */
                        EMIT2(0x39, add_2reg(0xC0, dreg_lo, sreg_lo));
                        goto emit_cond_jmp;
                }
                case BPF_JMP | BPF_JSET | BPF_X: {
                        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
                        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;
                        u8 sreg_lo = sstk ? IA32_ECX : src_lo;
                        u8 sreg_hi = sstk ? IA32_EBX : src_hi;

                        if (dstk) {
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(dst_lo));
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                                      STACK_VAR(dst_hi));
                        }

                        if (sstk) {
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_ECX),
                                      STACK_VAR(src_lo));
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EBX),
                                      STACK_VAR(src_hi));
                        }
                        /* and dreg_lo,sreg_lo */
                        EMIT2(0x23, add_2reg(0xC0, sreg_lo, dreg_lo));
                        if (is_jmp64) {
                                /* and dreg_hi,sreg_hi */
                                EMIT2(0x23, add_2reg(0xC0, sreg_hi, dreg_hi));
                                /* or dreg_lo,dreg_hi */
                                EMIT2(0x09, add_2reg(0xC0, dreg_lo, dreg_hi));
                        }
                        goto emit_cond_jmp;
                }
                case BPF_JMP | BPF_JSET | BPF_K: {
                        u32 hi;
                        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
                        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;
                        u8 sreg_lo = IA32_ECX;
                        u8 sreg_hi = IA32_EBX;

                        if (dstk) {
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(dst_lo));
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                                      STACK_VAR(dst_hi));
                        }
                        hi = imm32 & (1<<31) ? (u32)~0 : 0;

                        /* mov ecx,imm32 */
                        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_ECX), imm32);
                        /* mov ebx,imm32 */
                        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EBX), hi);

                        /* and dreg_lo,sreg_lo */
                        EMIT2(0x23, add_2reg(0xC0, sreg_lo, dreg_lo));
                        /* and dreg_hi,sreg_hi */
                        EMIT2(0x23, add_2reg(0xC0, sreg_hi, dreg_hi));
                        /* or dreg_lo,dreg_hi */
                        EMIT2(0x09, add_2reg(0xC0, dreg_lo, dreg_hi));
                        goto emit_cond_jmp;
                }
                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_JSLE | BPF_K:
                case BPF_JMP | BPF_JSLT | BPF_K:
                case BPF_JMP | BPF_JSGE | BPF_K: {
                        u32 hi;
                        u8 dreg_lo = dstk ? IA32_EAX : dst_lo;
                        u8 dreg_hi = dstk ? IA32_EDX : dst_hi;
                        u8 sreg_lo = IA32_ECX;
                        u8 sreg_hi = IA32_EBX;

                        if (dstk) {
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EAX),
                                      STACK_VAR(dst_lo));
                                EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX),
                                      STACK_VAR(dst_hi));
                        }

                        hi = imm32 & (1<<31) ? (u32)~0 : 0;
                        /* mov ecx,imm32 */
                        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_ECX), imm32);
                        /* mov ebx,imm32 */
                        EMIT2_off32(0xC7, add_1reg(0xC0, IA32_EBX), hi);

                        /* cmp dreg_hi,sreg_hi */
                        EMIT2(0x39, add_2reg(0xC0, dreg_hi, sreg_hi));
                        EMIT2(IA32_JNE, 2);
                        /* cmp dreg_lo,sreg_lo */
                        EMIT2(0x39, add_2reg(0xC0, dreg_lo, sreg_lo));

emit_cond_jmp:          /* Convert BPF opcode to x86 */
                        switch (BPF_OP(code)) {
                        case BPF_JEQ:
                                jmp_cond = IA32_JE;
                                break;
                        case BPF_JSET:
                        case BPF_JNE:
                                jmp_cond = IA32_JNE;
                                break;

                        case BPF_JGT:
                                /* GT is unsigned '>', JA in x86 */
                                jmp_cond = IA32_JA;
                                break;
                        case BPF_JLT:
                                /* LT is unsigned '<', JB in x86 */
                                jmp_cond = IA32_JB;
                                break;
                        case BPF_JGE:
                                /* GE is unsigned '>=', JAE in x86 */
                                jmp_cond = IA32_JAE;
                                break;
                        case BPF_JLE:
                                /* LE is unsigned '<=', JBE in x86 */
                                jmp_cond = IA32_JBE;
                                break;
                        case BPF_JSGT:
                                /* Signed '>', GT in x86 */
                                jmp_cond = IA32_JG;
                                break;
                        case BPF_JSLT:
                                /* Signed '<', LT in x86 */
                                jmp_cond = IA32_JL;
                                break;
                        case BPF_JSGE:
                                /* Signed '>=', GE in x86 */
                                jmp_cond = IA32_JGE;
                                break;
                        case BPF_JSLE:
                                /* Signed '<=', LE in x86 */
                                jmp_cond = IA32_JLE;
                                break;
                        default: /* to silence GCC warning */
                                return -EFAULT;
                        }
                        jmp_offset = addrs[i + insn->off] - addrs[i];
                        if (is_imm8(jmp_offset)) {
                                EMIT2(jmp_cond, jmp_offset);
                        } else if (is_simm32(jmp_offset)) {
                                EMIT2_off32(0x0F, jmp_cond + 0x10, jmp_offset);
                        } else {
                                pr_err("cond_jmp gen bug %llx\n", jmp_offset);
                                return -EFAULT;
                        }

                        break;
                }
                case BPF_JMP | BPF_JA:
                        if (insn->off == -1)
                                /* -1 jmp instructions will always jump
                                 * backwards two bytes. Explicitly handling
                                 * this case avoids wasting too many passes
                                 * when there are long sequences of replaced
                                 * dead code.
                                 */
                                jmp_offset = -2;
                        else
                                jmp_offset = addrs[i + insn->off] - addrs[i];

                        if (!jmp_offset)
                                /* Optimize out nop jumps */
                                break;
emit_jmp:
                        if (is_imm8(jmp_offset)) {
                                EMIT2(0xEB, jmp_offset);
                        } else if (is_simm32(jmp_offset)) {
                                EMIT1_off32(0xE9, jmp_offset);
                        } else {
                                pr_err("jmp gen bug %llx\n", jmp_offset);
                                return -EFAULT;
                        }
                        break;
                /* STX XADD: lock *(u32 *)(dst + off) += src */
                case BPF_STX | BPF_XADD | BPF_W:
                /* STX XADD: lock *(u64 *)(dst + off) += src */
                case BPF_STX | BPF_XADD | BPF_DW:
                        goto notyet;
                case BPF_JMP | BPF_EXIT:
                        if (seen_exit) {
                                jmp_offset = ctx->cleanup_addr - addrs[i];
                                goto emit_jmp;
                        }
                        seen_exit = true;
                        /* Update cleanup_addr */
                        ctx->cleanup_addr = proglen;
                        emit_epilogue(&prog, bpf_prog->aux->stack_depth);
                        break;
notyet:
                        pr_info_once("*** NOT YET: opcode %02x ***\n", code);
                        return -EFAULT;
                default:
                        /*
                         * This error will be seen if new instruction was added
                         * to interpreter, but not to JIT or if there is junk in
                         * bpf_prog
                         */
                        pr_err("bpf_jit: unknown opcode %02x\n", code);
                        return -EINVAL;
                }

                ilen = prog - temp;
                if (ilen > BPF_MAX_INSN_SIZE) {
                        pr_err("bpf_jit: fatal insn size error\n");
                        return -EFAULT;
                }

                if (image) {
                        if (unlikely(proglen + ilen > oldproglen)) {
                                pr_err("bpf_jit: fatal error\n");
                                return -EFAULT;
                        }
                        memcpy(image + proglen, temp, ilen);
                }
                proglen += ilen;
                addrs[i] = proglen;
                prog = temp;
        }
        return proglen;
}

bool bpf_jit_needs_zext(void)
{
        return true;
}

struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
        struct bpf_binary_header *header = NULL;
        struct bpf_prog *tmp, *orig_prog = prog;
        int proglen, oldproglen = 0;
        struct jit_context ctx = {};
        bool tmp_blinded = false;
        u8 *image = NULL;
        int *addrs;
        int pass;
        int i;

        if (!prog->jit_requested)
                return orig_prog;

        tmp = bpf_jit_blind_constants(prog);
        /*
         * If blinding was requested and we failed during blinding,
         * we must fall back to the interpreter.
         */
        if (IS_ERR(tmp))
                return orig_prog;
        if (tmp != prog) {
                tmp_blinded = true;
                prog = tmp;
        }

        addrs = kmalloc_array(prog->len, sizeof(*addrs), GFP_KERNEL);
        if (!addrs) {
                prog = orig_prog;
                goto out;
        }

        /*
         * Before first pass, make a rough estimation of addrs[]
         * each BPF instruction is translated to less than 64 bytes
         */
        for (proglen = 0, i = 0; i < prog->len; i++) {
                proglen += 64;
                addrs[i] = proglen;
        }
        ctx.cleanup_addr = proglen;

        /*
         * JITed image shrinks with every pass and the loop iterates
         * until the image stops shrinking. Very large BPF programs
         * may converge on the last pass. In such case do one more
         * pass to emit the final image.
         */
        for (pass = 0; pass < 20 || image; pass++) {
                proglen = do_jit(prog, addrs, image, oldproglen, &ctx);
                if (proglen <= 0) {
out_image:
                        image = NULL;
                        if (header)
                                bpf_jit_binary_free(header);
                        prog = orig_prog;
                        goto out_addrs;
                }
                if (image) {
                        if (proglen != oldproglen) {
                                pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
                                       proglen, oldproglen);
                                goto out_image;
                        }
                        break;
                }
                if (proglen == oldproglen) {
                        header = bpf_jit_binary_alloc(proglen, &image,
                                                      1, jit_fill_hole);
                        if (!header) {
                                prog = orig_prog;
                                goto out_addrs;
                        }
                }
                oldproglen = proglen;
                cond_resched();
        }

        if (bpf_jit_enable > 1)
                bpf_jit_dump(prog->len, proglen, pass + 1, image);

        if (image) {
                bpf_jit_binary_lock_ro(header);
                prog->bpf_func = (void *)image;
                prog->jited = 1;
                prog->jited_len = proglen;
        } else {
                prog = orig_prog;
        }

out_addrs:
        kfree(addrs);
out:
        if (tmp_blinded)
                bpf_jit_prog_release_other(prog, prog == orig_prog ?
                                           tmp : orig_prog);
        return prog;
}