/* bpf_jit_comp.c : BPF JIT compiler
 *
 * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com)
 * Internal BPF Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 *
 * 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; version 2
 * of the License.
 */
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include <asm/cacheflush.h>
#include <linux/bpf.h>

int bpf_jit_enable __read_mostly;

/*
 * assembly code in arch/x86/net/bpf_jit.S
 */
extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[];
extern u8 sk_load_byte_positive_offset[];
extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
extern u8 sk_load_byte_negative_offset[];

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)

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

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

/* mov dst, src */
#define EMIT_mov(DST, SRC) \
        do {if (DST != SRC) \
                EMIT3(add_2mod(0x48, DST, SRC), 0x89, add_2reg(0xC0, DST, SRC)); \
        } while (0)

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;
}

/* list of x86 cond jumps opcodes (. + s8)
 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
 */
#define X86_JB  0x72
#define X86_JAE 0x73
#define X86_JE  0x74
#define X86_JNE 0x75
#define X86_JBE 0x76
#define X86_JA  0x77
#define X86_JGE 0x7D
#define X86_JG  0x7F

static void bpf_flush_icache(void *start, void *end)
{
        mm_segment_t old_fs = get_fs();

        set_fs(KERNEL_DS);
        smp_wmb();
        flush_icache_range((unsigned long)start, (unsigned long)end);
        set_fs(old_fs);
}

#define CHOOSE_LOAD_FUNC(K, func) \
        ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)

/* pick a register outside of BPF range for JIT internal work */
#define AUX_REG (MAX_BPF_REG + 1)

/* the following table maps BPF registers to x64 registers.
 * x64 register r12 is unused, since if used as base address register
 * in load/store instructions, it always needs an extra byte of encoding
 */
static const int reg2hex[] = {
        [BPF_REG_0] = 0,  /* rax */
        [BPF_REG_1] = 7,  /* rdi */
        [BPF_REG_2] = 6,  /* rsi */
        [BPF_REG_3] = 2,  /* rdx */
        [BPF_REG_4] = 1,  /* rcx */
        [BPF_REG_5] = 0,  /* r8 */
        [BPF_REG_6] = 3,  /* rbx callee saved */
        [BPF_REG_7] = 5,  /* r13 callee saved */
        [BPF_REG_8] = 6,  /* r14 callee saved */
        [BPF_REG_9] = 7,  /* r15 callee saved */
        [BPF_REG_FP] = 5, /* rbp readonly */
        [AUX_REG] = 3,    /* r11 temp register */
};

/* is_ereg() == true if BPF register 'reg' maps to x64 r8..r15
 * which need extra byte of encoding.
 * rax,rcx,...,rbp have simpler encoding
 */
static bool is_ereg(u32 reg)
{
        return (1 << reg) & (BIT(BPF_REG_5) |
                             BIT(AUX_REG) |
                             BIT(BPF_REG_7) |
                             BIT(BPF_REG_8) |
                             BIT(BPF_REG_9));
}

/* add modifiers if 'reg' maps to x64 registers r8..r15 */
static u8 add_1mod(u8 byte, u32 reg)
{
        if (is_ereg(reg))
                byte |= 1;
        return byte;
}

static u8 add_2mod(u8 byte, u32 r1, u32 r2)
{
        if (is_ereg(r1))
                byte |= 1;
        if (is_ereg(r2))
                byte |= 4;
        return byte;
}

/* encode 'dst_reg' register into x64 opcode 'byte' */
static u8 add_1reg(u8 byte, u32 dst_reg)
{
        return byte + reg2hex[dst_reg];
}

/* encode 'dst_reg' and 'src_reg' registers into x64 opcode 'byte' */
static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg)
{
        return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3);
}

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

struct jit_context {
        int cleanup_addr; /* epilogue code offset */
        bool seen_ld_abs;
};

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

#define STACKSIZE \
        (MAX_BPF_STACK + \
         32 /* space for rbx, r13, r14, r15 */ + \
         8 /* space for skb_copy_bits() buffer */)

#define PROLOGUE_SIZE 48

/* emit x64 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)
{
        u8 *prog = *pprog;
        int cnt = 0;

        EMIT1(0x55); /* push rbp */
        EMIT3(0x48, 0x89, 0xE5); /* mov rbp,rsp */

        /* sub rsp, STACKSIZE */
        EMIT3_off32(0x48, 0x81, 0xEC, STACKSIZE);

        /* all classic BPF filters use R6(rbx) save it */

        /* mov qword ptr [rbp-X],rbx */
        EMIT3_off32(0x48, 0x89, 0x9D, -STACKSIZE);

        /* bpf_convert_filter() maps classic BPF register X to R7 and uses R8
         * as temporary, so all tcpdump filters need to spill/fill R7(r13) and
         * R8(r14). R9(r15) spill could be made conditional, but there is only
         * one 'bpf_error' return path out of helper functions inside bpf_jit.S
         * The overhead of extra spill is negligible for any filter other
         * than synthetic ones. Therefore not worth adding complexity.
         */

        /* mov qword ptr [rbp-X],r13 */
        EMIT3_off32(0x4C, 0x89, 0xAD, -STACKSIZE + 8);
        /* mov qword ptr [rbp-X],r14 */
        EMIT3_off32(0x4C, 0x89, 0xB5, -STACKSIZE + 16);
        /* mov qword ptr [rbp-X],r15 */
        EMIT3_off32(0x4C, 0x89, 0xBD, -STACKSIZE + 24);

        /* Clear the tail call counter (tail_call_cnt): for eBPF tail calls
         * we need to reset the counter to 0. It's done in two instructions,
         * resetting rax register to 0 (xor on eax gets 0 extended), and
         * moving it to the counter location.
         */

        /* xor eax, eax */
        EMIT2(0x31, 0xc0);
        /* mov qword ptr [rbp-X], rax */
        EMIT3_off32(0x48, 0x89, 0x85, -STACKSIZE + 32);

        BUILD_BUG_ON(cnt != PROLOGUE_SIZE);
        *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 label1, label2, label3;
        int cnt = 0;

        /* rdi - pointer to ctx
         * rsi - pointer to bpf_array
         * rdx - index in bpf_array
         */

        /* if (index >= array->map.max_entries)
         *   goto out;
         */
        EMIT4(0x48, 0x8B, 0x46,                   /* mov rax, qword ptr [rsi + 16] */
              offsetof(struct bpf_array, map.max_entries));
        EMIT3(0x48, 0x39, 0xD0);                  /* cmp rax, rdx */
#define OFFSET1 47 /* number of bytes to jump */
        EMIT2(X86_JBE, OFFSET1);                  /* jbe out */
        label1 = cnt;

        /* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
         *   goto out;
         */
        EMIT2_off32(0x8B, 0x85, -STACKSIZE + 36); /* mov eax, dword ptr [rbp - 516] */
        EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);     /* cmp eax, MAX_TAIL_CALL_CNT */
#define OFFSET2 36
        EMIT2(X86_JA, OFFSET2);                   /* ja out */
        label2 = cnt;
        EMIT3(0x83, 0xC0, 0x01);                  /* add eax, 1 */
        EMIT2_off32(0x89, 0x85, -STACKSIZE + 36); /* mov dword ptr [rbp - 516], eax */

        /* prog = array->ptrs[index]; */
        EMIT4_off32(0x48, 0x8D, 0x84, 0xD6,       /* lea rax, [rsi + rdx * 8 + offsetof(...)] */
                    offsetof(struct bpf_array, ptrs));
        EMIT3(0x48, 0x8B, 0x00);                  /* mov rax, qword ptr [rax] */

        /* if (prog == NULL)
         *   goto out;
         */
        EMIT4(0x48, 0x83, 0xF8, 0x00);            /* cmp rax, 0 */
#define OFFSET3 10
        EMIT2(X86_JE, OFFSET3);                   /* je out */
        label3 = cnt;

        /* goto *(prog->bpf_func + prologue_size); */
        EMIT4(0x48, 0x8B, 0x40,                   /* mov rax, qword ptr [rax + 32] */
              offsetof(struct bpf_prog, bpf_func));
        EMIT4(0x48, 0x83, 0xC0, PROLOGUE_SIZE);   /* add rax, prologue_size */

        /* now we're ready to jump into next BPF program
         * rdi == ctx (1st arg)
         * rax == prog->bpf_func + prologue_size
         */
        EMIT2(0xFF, 0xE0);                        /* jmp rax */

        /* out: */
        BUILD_BUG_ON(cnt - label1 != OFFSET1);
        BUILD_BUG_ON(cnt - label2 != OFFSET2);
        BUILD_BUG_ON(cnt - label3 != OFFSET3);
        *pprog = prog;
}


static void emit_load_skb_data_hlen(u8 **pprog)
{
        u8 *prog = *pprog;
        int cnt = 0;

        /* r9d = skb->len - skb->data_len (headlen)
         * r10 = skb->data
         */
        /* mov %r9d, off32(%rdi) */
        EMIT3_off32(0x44, 0x8b, 0x8f, offsetof(struct sk_buff, len));

        /* sub %r9d, off32(%rdi) */
        EMIT3_off32(0x44, 0x2b, 0x8f, offsetof(struct sk_buff, data_len));

        /* mov %r10, off32(%rdi) */
        EMIT3_off32(0x4c, 0x8b, 0x97, offsetof(struct sk_buff, data));
        *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_ld_abs = ctx->seen_ld_abs | (oldproglen == 0);
        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);

        if (seen_ld_abs)
                emit_load_skb_data_hlen(&prog);

        for (i = 0; i < insn_cnt; i++, insn++) {
                const s32 imm32 = insn->imm;
                u32 dst_reg = insn->dst_reg;
                u32 src_reg = insn->src_reg;
                u8 b1 = 0, b2 = 0, b3 = 0;
                s64 jmp_offset;
                u8 jmp_cond;
                bool reload_skb_data;
                int ilen;
                u8 *func;

                switch (insn->code) {
                        /* ALU */
                case BPF_ALU | BPF_ADD | BPF_X:
                case BPF_ALU | BPF_SUB | BPF_X:
                case BPF_ALU | BPF_AND | BPF_X:
                case BPF_ALU | BPF_OR | BPF_X:
                case BPF_ALU | BPF_XOR | BPF_X:
                case BPF_ALU64 | BPF_ADD | BPF_X:
                case BPF_ALU64 | BPF_SUB | BPF_X:
                case BPF_ALU64 | BPF_AND | BPF_X:
                case BPF_ALU64 | BPF_OR | BPF_X:
                case BPF_ALU64 | BPF_XOR | BPF_X:
                        switch (BPF_OP(insn->code)) {
                        case BPF_ADD: b2 = 0x01; break;
                        case BPF_SUB: b2 = 0x29; break;
                        case BPF_AND: b2 = 0x21; break;
                        case BPF_OR: b2 = 0x09; break;
                        case BPF_XOR: b2 = 0x31; break;
                        }
                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                EMIT1(add_2mod(0x48, dst_reg, src_reg));
                        else if (is_ereg(dst_reg) || is_ereg(src_reg))
                                EMIT1(add_2mod(0x40, dst_reg, src_reg));
                        EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg));
                        break;

                        /* mov dst, src */
                case BPF_ALU64 | BPF_MOV | BPF_X:
                        EMIT_mov(dst_reg, src_reg);
                        break;

                        /* mov32 dst, src */
                case BPF_ALU | BPF_MOV | BPF_X:
                        if (is_ereg(dst_reg) || is_ereg(src_reg))
                                EMIT1(add_2mod(0x40, dst_reg, src_reg));
                        EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg));
                        break;

                        /* neg dst */
                case BPF_ALU | BPF_NEG:
                case BPF_ALU64 | BPF_NEG:
                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                EMIT1(add_1mod(0x48, dst_reg));
                        else if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, dst_reg));
                        EMIT2(0xF7, add_1reg(0xD8, dst_reg));
                        break;

                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_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:
                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                EMIT1(add_1mod(0x48, dst_reg));
                        else if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, dst_reg));

                        switch (BPF_OP(insn->code)) {
                        case BPF_ADD: b3 = 0xC0; break;
                        case BPF_SUB: b3 = 0xE8; break;
                        case BPF_AND: b3 = 0xE0; break;
                        case BPF_OR: b3 = 0xC8; break;
                        case BPF_XOR: b3 = 0xF0; break;
                        }

                        if (is_imm8(imm32))
                                EMIT3(0x83, add_1reg(b3, dst_reg), imm32);
                        else
                                EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32);
                        break;

                case BPF_ALU64 | BPF_MOV | BPF_K:
                        /* optimization: if imm32 is positive,
                         * use 'mov eax, imm32' (which zero-extends imm32)
                         * to save 2 bytes
                         */
                        if (imm32 < 0) {
                                /* 'mov rax, imm32' sign extends imm32 */
                                b1 = add_1mod(0x48, dst_reg);
                                b2 = 0xC7;
                                b3 = 0xC0;
                                EMIT3_off32(b1, b2, add_1reg(b3, dst_reg), imm32);
                                break;
                        }

                case BPF_ALU | BPF_MOV | BPF_K:
                        /* optimization: if imm32 is zero, use 'xor <dst>,<dst>'
                         * to save 3 bytes.
                         */
                        if (imm32 == 0) {
                                if (is_ereg(dst_reg))
                                        EMIT1(add_2mod(0x40, dst_reg, dst_reg));
                                b2 = 0x31; /* xor */
                                b3 = 0xC0;
                                EMIT2(b2, add_2reg(b3, dst_reg, dst_reg));
                                break;
                        }

                        /* mov %eax, imm32 */
                        if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, dst_reg));
                        EMIT1_off32(add_1reg(0xB8, dst_reg), imm32);
                        break;

                case BPF_LD | BPF_IMM | BPF_DW:
                        if (insn[1].code != 0 || insn[1].src_reg != 0 ||
                            insn[1].dst_reg != 0 || insn[1].off != 0) {
                                /* verifier must catch invalid insns */
                                pr_err("invalid BPF_LD_IMM64 insn\n");
                                return -EINVAL;
                        }

                        /* optimization: if imm64 is zero, use 'xor <dst>,<dst>'
                         * to save 7 bytes.
                         */
                        if (insn[0].imm == 0 && insn[1].imm == 0) {
                                b1 = add_2mod(0x48, dst_reg, dst_reg);
                                b2 = 0x31; /* xor */
                                b3 = 0xC0;
                                EMIT3(b1, b2, add_2reg(b3, dst_reg, dst_reg));

                                insn++;
                                i++;
                                break;
                        }

                        /* movabsq %rax, imm64 */
                        EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg));
                        EMIT(insn[0].imm, 4);
                        EMIT(insn[1].imm, 4);

                        insn++;
                        i++;
                        break;

                        /* dst %= src, dst /= src, dst %= imm32, dst /= imm32 */
                case BPF_ALU | BPF_MOD | BPF_X:
                case BPF_ALU | BPF_DIV | BPF_X:
                case BPF_ALU | BPF_MOD | BPF_K:
                case BPF_ALU | BPF_DIV | BPF_K:
                case BPF_ALU64 | BPF_MOD | BPF_X:
                case BPF_ALU64 | BPF_DIV | BPF_X:
                case BPF_ALU64 | BPF_MOD | BPF_K:
                case BPF_ALU64 | BPF_DIV | BPF_K:
                        EMIT1(0x50); /* push rax */
                        EMIT1(0x52); /* push rdx */

                        if (BPF_SRC(insn->code) == BPF_X)
                                /* mov r11, src_reg */
                                EMIT_mov(AUX_REG, src_reg);
                        else
                                /* mov r11, imm32 */
                                EMIT3_off32(0x49, 0xC7, 0xC3, imm32);

                        /* mov rax, dst_reg */
                        EMIT_mov(BPF_REG_0, dst_reg);

                        /* xor edx, edx
                         * equivalent to 'xor rdx, rdx', but one byte less
                         */
                        EMIT2(0x31, 0xd2);

                        if (BPF_SRC(insn->code) == BPF_X) {
                                /* if (src_reg == 0) return 0 */

                                /* cmp r11, 0 */
                                EMIT4(0x49, 0x83, 0xFB, 0x00);

                                /* jne .+9 (skip over pop, pop, xor and jmp) */
                                EMIT2(X86_JNE, 1 + 1 + 2 + 5);
                                EMIT1(0x5A); /* pop rdx */
                                EMIT1(0x58); /* pop rax */
                                EMIT2(0x31, 0xc0); /* xor eax, eax */

                                /* jmp cleanup_addr
                                 * addrs[i] - 11, because there are 11 bytes
                                 * after this insn: div, mov, pop, pop, mov
                                 */
                                jmp_offset = ctx->cleanup_addr - (addrs[i] - 11);
                                EMIT1_off32(0xE9, jmp_offset);
                        }

                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                /* div r11 */
                                EMIT3(0x49, 0xF7, 0xF3);
                        else
                                /* div r11d */
                                EMIT3(0x41, 0xF7, 0xF3);

                        if (BPF_OP(insn->code) == BPF_MOD)
                                /* mov r11, rdx */
                                EMIT3(0x49, 0x89, 0xD3);
                        else
                                /* mov r11, rax */
                                EMIT3(0x49, 0x89, 0xC3);

                        EMIT1(0x5A); /* pop rdx */
                        EMIT1(0x58); /* pop rax */

                        /* mov dst_reg, r11 */
                        EMIT_mov(dst_reg, AUX_REG);
                        break;

                case BPF_ALU | BPF_MUL | BPF_K:
                case BPF_ALU | BPF_MUL | BPF_X:
                case BPF_ALU64 | BPF_MUL | BPF_K:
                case BPF_ALU64 | BPF_MUL | BPF_X:
                        EMIT1(0x50); /* push rax */
                        EMIT1(0x52); /* push rdx */

                        /* mov r11, dst_reg */
                        EMIT_mov(AUX_REG, dst_reg);

                        if (BPF_SRC(insn->code) == BPF_X)
                                /* mov rax, src_reg */
                                EMIT_mov(BPF_REG_0, src_reg);
                        else
                                /* mov rax, imm32 */
                                EMIT3_off32(0x48, 0xC7, 0xC0, imm32);

                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                EMIT1(add_1mod(0x48, AUX_REG));
                        else if (is_ereg(AUX_REG))
                                EMIT1(add_1mod(0x40, AUX_REG));
                        /* mul(q) r11 */
                        EMIT2(0xF7, add_1reg(0xE0, AUX_REG));

                        /* mov r11, rax */
                        EMIT_mov(AUX_REG, BPF_REG_0);

                        EMIT1(0x5A); /* pop rdx */
                        EMIT1(0x58); /* pop rax */

                        /* mov dst_reg, r11 */
                        EMIT_mov(dst_reg, AUX_REG);
                        break;

                        /* shifts */
                case BPF_ALU | BPF_LSH | BPF_K:
                case BPF_ALU | BPF_RSH | BPF_K:
                case BPF_ALU | BPF_ARSH | BPF_K:
                case BPF_ALU64 | BPF_LSH | BPF_K:
                case BPF_ALU64 | BPF_RSH | BPF_K:
                case BPF_ALU64 | BPF_ARSH | BPF_K:
                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                EMIT1(add_1mod(0x48, dst_reg));
                        else if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, dst_reg));

                        switch (BPF_OP(insn->code)) {
                        case BPF_LSH: b3 = 0xE0; break;
                        case BPF_RSH: b3 = 0xE8; break;
                        case BPF_ARSH: b3 = 0xF8; break;
                        }
                        EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
                        break;

                case BPF_ALU | BPF_LSH | BPF_X:
                case BPF_ALU | BPF_RSH | BPF_X:
                case BPF_ALU | BPF_ARSH | BPF_X:
                case BPF_ALU64 | BPF_LSH | BPF_X:
                case BPF_ALU64 | BPF_RSH | BPF_X:
                case BPF_ALU64 | BPF_ARSH | BPF_X:

                        /* check for bad case when dst_reg == rcx */
                        if (dst_reg == BPF_REG_4) {
                                /* mov r11, dst_reg */
                                EMIT_mov(AUX_REG, dst_reg);
                                dst_reg = AUX_REG;
                        }

                        if (src_reg != BPF_REG_4) { /* common case */
                                EMIT1(0x51); /* push rcx */

                                /* mov rcx, src_reg */
                                EMIT_mov(BPF_REG_4, src_reg);
                        }

                        /* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */
                        if (BPF_CLASS(insn->code) == BPF_ALU64)
                                EMIT1(add_1mod(0x48, dst_reg));
                        else if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, dst_reg));

                        switch (BPF_OP(insn->code)) {
                        case BPF_LSH: b3 = 0xE0; break;
                        case BPF_RSH: b3 = 0xE8; break;
                        case BPF_ARSH: b3 = 0xF8; break;
                        }
                        EMIT2(0xD3, add_1reg(b3, dst_reg));

                        if (src_reg != BPF_REG_4)
                                EMIT1(0x59); /* pop rcx */

                        if (insn->dst_reg == BPF_REG_4)
                                /* mov dst_reg, r11 */
                                EMIT_mov(insn->dst_reg, AUX_REG);
                        break;

                case BPF_ALU | BPF_END | BPF_FROM_BE:
                        switch (imm32) {
                        case 16:
                                /* emit 'ror %ax, 8' to swap lower 2 bytes */
                                EMIT1(0x66);
                                if (is_ereg(dst_reg))
                                        EMIT1(0x41);
                                EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8);

                                /* emit 'movzwl eax, ax' */
                                if (is_ereg(dst_reg))
                                        EMIT3(0x45, 0x0F, 0xB7);
                                else
                                        EMIT2(0x0F, 0xB7);
                                EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
                                break;
                        case 32:
                                /* emit 'bswap eax' to swap lower 4 bytes */
                                if (is_ereg(dst_reg))
                                        EMIT2(0x41, 0x0F);
                                else
                                        EMIT1(0x0F);
                                EMIT1(add_1reg(0xC8, dst_reg));
                                break;
                        case 64:
                                /* emit 'bswap rax' to swap 8 bytes */
                                EMIT3(add_1mod(0x48, dst_reg), 0x0F,
                                      add_1reg(0xC8, dst_reg));
                                break;
                        }
                        break;

                case BPF_ALU | BPF_END | BPF_FROM_LE:
                        switch (imm32) {
                        case 16:
                                /* emit 'movzwl eax, ax' to zero extend 16-bit
                                 * into 64 bit
                                 */
                                if (is_ereg(dst_reg))
                                        EMIT3(0x45, 0x0F, 0xB7);
                                else
                                        EMIT2(0x0F, 0xB7);
                                EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
                                break;
                        case 32:
                                /* emit 'mov eax, eax' to clear upper 32-bits */
                                if (is_ereg(dst_reg))
                                        EMIT1(0x45);
                                EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg));
                                break;
                        case 64:
                                /* nop */
                                break;
                        }
                        break;

                        /* ST: *(u8*)(dst_reg + off) = imm */
                case BPF_ST | BPF_MEM | BPF_B:
                        if (is_ereg(dst_reg))
                                EMIT2(0x41, 0xC6);
                        else
                                EMIT1(0xC6);
                        goto st;
                case BPF_ST | BPF_MEM | BPF_H:
                        if (is_ereg(dst_reg))
                                EMIT3(0x66, 0x41, 0xC7);
                        else
                                EMIT2(0x66, 0xC7);
                        goto st;
                case BPF_ST | BPF_MEM | BPF_W:
                        if (is_ereg(dst_reg))
                                EMIT2(0x41, 0xC7);
                        else
                                EMIT1(0xC7);
                        goto st;
                case BPF_ST | BPF_MEM | BPF_DW:
                        EMIT2(add_1mod(0x48, dst_reg), 0xC7);

st:                     if (is_imm8(insn->off))
                                EMIT2(add_1reg(0x40, dst_reg), insn->off);
                        else
                                EMIT1_off32(add_1reg(0x80, dst_reg), insn->off);

                        EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(insn->code)));
                        break;

                        /* STX: *(u8*)(dst_reg + off) = src_reg */
                case BPF_STX | BPF_MEM | BPF_B:
                        /* emit 'mov byte ptr [rax + off], al' */
                        if (is_ereg(dst_reg) || is_ereg(src_reg) ||
                            /* have to add extra byte for x86 SIL, DIL regs */
                            src_reg == BPF_REG_1 || src_reg == BPF_REG_2)
                                EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88);
                        else
                                EMIT1(0x88);
                        goto stx;
                case BPF_STX | BPF_MEM | BPF_H:
                        if (is_ereg(dst_reg) || is_ereg(src_reg))
                                EMIT3(0x66, add_2mod(0x40, dst_reg, src_reg), 0x89);
                        else
                                EMIT2(0x66, 0x89);
                        goto stx;
                case BPF_STX | BPF_MEM | BPF_W:
                        if (is_ereg(dst_reg) || is_ereg(src_reg))
                                EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89);
                        else
                                EMIT1(0x89);
                        goto stx;
                case BPF_STX | BPF_MEM | BPF_DW:
                        EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89);
stx:                    if (is_imm8(insn->off))
                                EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off);
                        else
                                EMIT1_off32(add_2reg(0x80, dst_reg, src_reg),
                                            insn->off);
                        break;

                        /* LDX: dst_reg = *(u8*)(src_reg + off) */
                case BPF_LDX | BPF_MEM | BPF_B:
                        /* emit 'movzx rax, byte ptr [rax + off]' */
                        EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6);
                        goto ldx;
                case BPF_LDX | BPF_MEM | BPF_H:
                        /* emit 'movzx rax, word ptr [rax + off]' */
                        EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7);
                        goto ldx;
                case BPF_LDX | BPF_MEM | BPF_W:
                        /* emit 'mov eax, dword ptr [rax+0x14]' */
                        if (is_ereg(dst_reg) || is_ereg(src_reg))
                                EMIT2(add_2mod(0x40, src_reg, dst_reg), 0x8B);
                        else
                                EMIT1(0x8B);
                        goto ldx;
                case BPF_LDX | BPF_MEM | BPF_DW:
                        /* emit 'mov rax, qword ptr [rax+0x14]' */
                        EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B);
ldx:                    /* if insn->off == 0 we can save one extra byte, but
                         * special case of x86 r13 which always needs an offset
                         * is not worth the hassle
                         */
                        if (is_imm8(insn->off))
                                EMIT2(add_2reg(0x40, src_reg, dst_reg), insn->off);
                        else
                                EMIT1_off32(add_2reg(0x80, src_reg, dst_reg),
                                            insn->off);
                        break;

                        /* STX XADD: lock *(u32*)(dst_reg + off) += src_reg */
                case BPF_STX | BPF_XADD | BPF_W:
                        /* emit 'lock add dword ptr [rax + off], eax' */
                        if (is_ereg(dst_reg) || is_ereg(src_reg))
                                EMIT3(0xF0, add_2mod(0x40, dst_reg, src_reg), 0x01);
                        else
                                EMIT2(0xF0, 0x01);
                        goto xadd;
                case BPF_STX | BPF_XADD | BPF_DW:
                        EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01);
xadd:                   if (is_imm8(insn->off))
                                EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off);
                        else
                                EMIT1_off32(add_2reg(0x80, dst_reg, src_reg),
                                            insn->off);
                        break;

                        /* call */
                case BPF_JMP | BPF_CALL:
                        func = (u8 *) __bpf_call_base + imm32;
                        jmp_offset = func - (image + addrs[i]);
                        if (seen_ld_abs) {
                                reload_skb_data = bpf_helper_changes_skb_data(func);
                                if (reload_skb_data) {
                                        EMIT1(0x57); /* push %rdi */
                                        jmp_offset += 22; /* pop, mov, sub, mov */
                                } else {
                                        EMIT2(0x41, 0x52); /* push %r10 */
                                        EMIT2(0x41, 0x51); /* push %r9 */
                                        /* need to adjust jmp offset, since
                                         * pop %r9, pop %r10 take 4 bytes after call insn
                                         */
                                        jmp_offset += 4;
                                }
                        }
                        if (!imm32 || !is_simm32(jmp_offset)) {
                                pr_err("unsupported bpf func %d addr %p image %p\n",
                                       imm32, func, image);
                                return -EINVAL;
                        }
                        EMIT1_off32(0xE8, jmp_offset);
                        if (seen_ld_abs) {
                                if (reload_skb_data) {
                                        EMIT1(0x5F); /* pop %rdi */
                                        emit_load_skb_data_hlen(&prog);
                                } else {
                                        EMIT2(0x41, 0x59); /* pop %r9 */
                                        EMIT2(0x41, 0x5A); /* pop %r10 */
                                }
                        }
                        break;

                case BPF_JMP | BPF_CALL | BPF_X:
                        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_JGE | BPF_X:
                case BPF_JMP | BPF_JSGT | BPF_X:
                case BPF_JMP | BPF_JSGE | BPF_X:
                        /* cmp dst_reg, src_reg */
                        EMIT3(add_2mod(0x48, dst_reg, src_reg), 0x39,
                              add_2reg(0xC0, dst_reg, src_reg));
                        goto emit_cond_jmp;

                case BPF_JMP | BPF_JSET | BPF_X:
                        /* test dst_reg, src_reg */
                        EMIT3(add_2mod(0x48, dst_reg, src_reg), 0x85,
                              add_2reg(0xC0, dst_reg, src_reg));
                        goto emit_cond_jmp;

                case BPF_JMP | BPF_JSET | BPF_K:
                        /* test dst_reg, imm32 */
                        EMIT1(add_1mod(0x48, dst_reg));
                        EMIT2_off32(0xF7, add_1reg(0xC0, dst_reg), imm32);
                        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_JGE | BPF_K:
                case BPF_JMP | BPF_JSGT | BPF_K:
                case BPF_JMP | BPF_JSGE | BPF_K:
                        /* cmp dst_reg, imm8/32 */
                        EMIT1(add_1mod(0x48, dst_reg));

                        if (is_imm8(imm32))
                                EMIT3(0x83, add_1reg(0xF8, dst_reg), imm32);
                        else
                                EMIT2_off32(0x81, add_1reg(0xF8, dst_reg), imm32);

emit_cond_jmp:          /* convert BPF opcode to x86 */
                        switch (BPF_OP(insn->code)) {
                        case BPF_JEQ:
                                jmp_cond = X86_JE;
                                break;
                        case BPF_JSET:
                        case BPF_JNE:
                                jmp_cond = X86_JNE;
                                break;
                        case BPF_JGT:
                                /* GT is unsigned '>', JA in x86 */
                                jmp_cond = X86_JA;
                                break;
                        case BPF_JGE:
                                /* GE is unsigned '>=', JAE in x86 */
                                jmp_cond = X86_JAE;
                                break;
                        case BPF_JSGT:
                                /* signed '>', GT in x86 */
                                jmp_cond = X86_JG;
                                break;
                        case BPF_JSGE:
                                /* signed '>=', GE in x86 */
                                jmp_cond = X86_JGE;
                                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:
                        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;

                case BPF_LD | BPF_IND | BPF_W:
                        func = sk_load_word;
                        goto common_load;
                case BPF_LD | BPF_ABS | BPF_W:
                        func = CHOOSE_LOAD_FUNC(imm32, sk_load_word);
common_load:
                        ctx->seen_ld_abs = seen_ld_abs = true;
                        jmp_offset = func - (image + addrs[i]);
                        if (!func || !is_simm32(jmp_offset)) {
                                pr_err("unsupported bpf func %d addr %p image %p\n",
                                       imm32, func, image);
                                return -EINVAL;
                        }
                        if (BPF_MODE(insn->code) == BPF_ABS) {
                                /* mov %esi, imm32 */
                                EMIT1_off32(0xBE, imm32);
                        } else {
                                /* mov %rsi, src_reg */
                                EMIT_mov(BPF_REG_2, src_reg);
                                if (imm32) {
                                        if (is_imm8(imm32))
                                                /* add %esi, imm8 */
                                                EMIT3(0x83, 0xC6, imm32);
                                        else
                                                /* add %esi, imm32 */
                                                EMIT2_off32(0x81, 0xC6, imm32);
                                }
                        }
                        /* skb pointer is in R6 (%rbx), it will be copied into

                         * %rdi if skb_copy_bits() call is necessary.
                         * sk_load_* helpers also use %r10 and %r9d.
                         * See bpf_jit.S
                         */
                        EMIT1_off32(0xE8, jmp_offset); /* call */
                        break;

                case BPF_LD | BPF_IND | BPF_H:
                        func = sk_load_half;
                        goto common_load;
                case BPF_LD | BPF_ABS | BPF_H:
                        func = CHOOSE_LOAD_FUNC(imm32, sk_load_half);
                        goto common_load;
                case BPF_LD | BPF_IND | BPF_B:
                        func = sk_load_byte;
                        goto common_load;
                case BPF_LD | BPF_ABS | BPF_B:
                        func = CHOOSE_LOAD_FUNC(imm32, sk_load_byte);
                        goto common_load;

                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;
                        /* mov rbx, qword ptr [rbp-X] */
                        EMIT3_off32(0x48, 0x8B, 0x9D, -STACKSIZE);
                        /* mov r13, qword ptr [rbp-X] */
                        EMIT3_off32(0x4C, 0x8B, 0xAD, -STACKSIZE + 8);
                        /* mov r14, qword ptr [rbp-X] */
                        EMIT3_off32(0x4C, 0x8B, 0xB5, -STACKSIZE + 16);
                        /* mov r15, qword ptr [rbp-X] */
                        EMIT3_off32(0x4C, 0x8B, 0xBD, -STACKSIZE + 24);

                        EMIT1(0xC9); /* leave */
                        EMIT1(0xC3); /* ret */
                        break;

                default:
                        /* By design x64 JIT should support all BPF instructions
                         * 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", insn->code);
                        return -EINVAL;
                }

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

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

void bpf_jit_compile(struct bpf_prog *prog)
{
}

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

        if (!bpf_jit_enable)
                return;

        if (!prog || !prog->len)
                return;

        addrs = kmalloc(prog->len * sizeof(*addrs), GFP_KERNEL);
        if (!addrs)
                return;

        /* 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 < 10 || image; pass++) {
                proglen = do_jit(prog, addrs, image, oldproglen, &ctx);
                if (proglen <= 0) {
                        image = NULL;
                        if (header)
                                bpf_jit_binary_free(header);
                        goto out;
                }
                if (image) {
                        if (proglen != oldproglen) {
                                pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
                                       proglen, oldproglen);
                                goto out;
                        }
                        break;
                }
                if (proglen == oldproglen) {
                        header = bpf_jit_binary_alloc(proglen, &image,
                                                      1, jit_fill_hole);
                        if (!header)
                                goto out;
                }
                oldproglen = proglen;
        }

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

        if (image) {
                bpf_flush_icache(header, image + proglen);
                set_memory_ro((unsigned long)header, header->pages);
                prog->bpf_func = (void *)image;
                prog->jited = 1;
        }
out:
        kfree(addrs);
}

void bpf_jit_free(struct bpf_prog *fp)
{
        unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
        struct bpf_binary_header *header = (void *)addr;

        if (!fp->jited)
                goto free_filter;

        set_memory_rw(addr, header->pages);
        bpf_jit_binary_free(header);

free_filter:
        bpf_prog_unlock_free(fp);
}