// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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
 */
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include <linux/bpf.h>
#include <linux/memory.h>
#include <asm/extable.h>
#include <asm/set_memory.h>
#include <asm/nospec-branch.h>
#include <asm/text-patching.h>

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;
}

static bool is_uimm32(u64 value)
{
        return value == (u64)(u32)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_JL  0x7C
#define X86_JGE 0x7D
#define X86_JLE 0x7E
#define X86_JG  0x7F

/* Pick a register outside of BPF range for JIT internal work */
#define AUX_REG (MAX_BPF_JIT_REG + 1)
#define X86_REG_R9 (MAX_BPF_JIT_REG + 2)

/*
 * The following table maps BPF registers to x86-64 registers.
 *
 * x86-64 register R12 is unused, since if used as base address
 * register in load/store instructions, it always needs an
 * extra byte of encoding and is callee saved.
 *
 * x86-64 register R9 is not used by BPF programs, but can be used by BPF
 * trampoline. x86-64 register R10 is used for blinding (if enabled).
 */
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 */
        [BPF_REG_AX] = 2, /* R10 temp register */
        [AUX_REG] = 3,    /* R11 temp register */
        [X86_REG_R9] = 1, /* R9 register, 6th function argument */
};

static const int reg2pt_regs[] = {
        [BPF_REG_0] = offsetof(struct pt_regs, ax),
        [BPF_REG_1] = offsetof(struct pt_regs, di),
        [BPF_REG_2] = offsetof(struct pt_regs, si),
        [BPF_REG_3] = offsetof(struct pt_regs, dx),
        [BPF_REG_4] = offsetof(struct pt_regs, cx),
        [BPF_REG_5] = offsetof(struct pt_regs, r8),
        [BPF_REG_6] = offsetof(struct pt_regs, bx),
        [BPF_REG_7] = offsetof(struct pt_regs, r13),
        [BPF_REG_8] = offsetof(struct pt_regs, r14),
        [BPF_REG_9] = offsetof(struct pt_regs, r15),
};

/*
 * is_ereg() == true if BPF register 'reg' maps to x86-64 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) |
                             BIT(X86_REG_R9) |
                             BIT(BPF_REG_AX));
}

static bool is_axreg(u32 reg)
{
        return reg == BPF_REG_0;
}

/* Add modifiers if 'reg' maps to x86-64 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 x86-64 opcode 'byte' */
static u8 add_1reg(u8 byte, u32 dst_reg)
{
        return byte + reg2hex[dst_reg];
}

/* Encode 'dst_reg' and 'src_reg' registers into x86-64 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 */
};

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

/* Number of bytes emit_patch() needs to generate instructions */
#define X86_PATCH_SIZE          5

#define PROLOGUE_SIZE           25

/*
 * Emit x86-64 prologue code for BPF program and check its size.
 * bpf_tail_call helper will skip it while jumping into another program
 */
static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf)
{
        u8 *prog = *pprog;
        int cnt = X86_PATCH_SIZE;

        /* BPF trampoline can be made to work without these nops,
         * but let's waste 5 bytes for now and optimize later
         */
        memcpy(prog, ideal_nops[NOP_ATOMIC5], cnt);
        prog += cnt;
        EMIT1(0x55);             /* push rbp */
        EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
        /* sub rsp, rounded_stack_depth */
        EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8));
        EMIT1(0x53);             /* push rbx */
        EMIT2(0x41, 0x55);       /* push r13 */
        EMIT2(0x41, 0x56);       /* push r14 */
        EMIT2(0x41, 0x57);       /* push r15 */
        if (!ebpf_from_cbpf) {
                /* zero init tail_call_cnt */
                EMIT2(0x6a, 0x00);
                BUILD_BUG_ON(cnt != PROLOGUE_SIZE);
        }
        *pprog = prog;
}

static int emit_patch(u8 **pprog, void *func, void *ip, u8 opcode)
{
        u8 *prog = *pprog;
        int cnt = 0;
        s64 offset;

        offset = func - (ip + X86_PATCH_SIZE);
        if (!is_simm32(offset)) {
                pr_err("Target call %p is out of range\n", func);
                return -ERANGE;
        }
        EMIT1_off32(opcode, offset);
        *pprog = prog;
        return 0;
}

static int emit_call(u8 **pprog, void *func, void *ip)
{
        return emit_patch(pprog, func, ip, 0xE8);
}

static int emit_jump(u8 **pprog, void *func, void *ip)
{
        return emit_patch(pprog, func, ip, 0xE9);
}

static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
                                void *old_addr, void *new_addr,
                                const bool text_live)
{
        const u8 *nop_insn = ideal_nops[NOP_ATOMIC5];
        u8 old_insn[X86_PATCH_SIZE];
        u8 new_insn[X86_PATCH_SIZE];
        u8 *prog;
        int ret;

        memcpy(old_insn, nop_insn, X86_PATCH_SIZE);
        if (old_addr) {
                prog = old_insn;
                ret = t == BPF_MOD_CALL ?
                      emit_call(&prog, old_addr, ip) :
                      emit_jump(&prog, old_addr, ip);
                if (ret)
                        return ret;
        }

        memcpy(new_insn, nop_insn, X86_PATCH_SIZE);
        if (new_addr) {
                prog = new_insn;
                ret = t == BPF_MOD_CALL ?
                      emit_call(&prog, new_addr, ip) :
                      emit_jump(&prog, new_addr, ip);
                if (ret)
                        return ret;
        }

        ret = -EBUSY;
        mutex_lock(&text_mutex);
        if (memcmp(ip, old_insn, X86_PATCH_SIZE))
                goto out;
        if (memcmp(ip, new_insn, X86_PATCH_SIZE)) {
                if (text_live)
                        text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL);
                else
                        memcpy(ip, new_insn, X86_PATCH_SIZE);
        }
        ret = 0;
out:
        mutex_unlock(&text_mutex);
        return ret;
}

int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
                       void *old_addr, void *new_addr)
{
        if (!is_kernel_text((long)ip) &&
            !is_bpf_text_address((long)ip))
                /* BPF poking in modules is not supported */
                return -EINVAL;

        return __bpf_arch_text_poke(ip, t, old_addr, new_addr, true);
}

/*
 * 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_indirect(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;
         */
        EMIT2(0x89, 0xD2);                        /* mov edx, edx */
        EMIT3(0x39, 0x56,                         /* cmp dword ptr [rsi + 16], edx */
              offsetof(struct bpf_array, map.max_entries));
#define OFFSET1 (41 + RETPOLINE_RAX_BPF_JIT_SIZE) /* 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, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */
        EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);     /* cmp eax, MAX_TAIL_CALL_CNT */
#define OFFSET2 (30 + RETPOLINE_RAX_BPF_JIT_SIZE)
        EMIT2(X86_JA, OFFSET2);                   /* ja out */
        label2 = cnt;
        EMIT3(0x83, 0xC0, 0x01);                  /* add eax, 1 */
        EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */

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

        /*
         * if (prog == NULL)
         *      goto out;
         */
        EMIT3(0x48, 0x85, 0xC0);                  /* test rax,rax */
#define OFFSET3 (8 + RETPOLINE_RAX_BPF_JIT_SIZE)
        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 */

        /*
         * Wow we're ready to jump into next BPF program
         * rdi == ctx (1st arg)
         * rax == prog->bpf_func + prologue_size
         */
        RETPOLINE_RAX_BPF_JIT();

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

static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke,
                                      u8 **pprog, int addr, u8 *image)
{
        u8 *prog = *pprog;
        int cnt = 0;

        /*
         * if (tail_call_cnt > MAX_TAIL_CALL_CNT)
         *      goto out;
         */
        EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */
        EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);         /* cmp eax, MAX_TAIL_CALL_CNT */
        EMIT2(X86_JA, 14);                            /* ja out */
        EMIT3(0x83, 0xC0, 0x01);                      /* add eax, 1 */
        EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */

        poke->ip = image + (addr - X86_PATCH_SIZE);
        poke->adj_off = PROLOGUE_SIZE;

        memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE);
        prog += X86_PATCH_SIZE;
        /* out: */

        *pprog = prog;
}

static void bpf_tail_call_direct_fixup(struct bpf_prog *prog)
{
        struct bpf_jit_poke_descriptor *poke;
        struct bpf_array *array;
        struct bpf_prog *target;
        int i, ret;

        for (i = 0; i < prog->aux->size_poke_tab; i++) {
                poke = &prog->aux->poke_tab[i];
                WARN_ON_ONCE(READ_ONCE(poke->ip_stable));

                if (poke->reason != BPF_POKE_REASON_TAIL_CALL)
                        continue;

                array = container_of(poke->tail_call.map, struct bpf_array, map);
                mutex_lock(&array->aux->poke_mutex);
                target = array->ptrs[poke->tail_call.key];
                if (target) {
                        /* Plain memcpy is used when image is not live yet
                         * and still not locked as read-only. Once poke
                         * location is active (poke->ip_stable), any parallel
                         * bpf_arch_text_poke() might occur still on the
                         * read-write image until we finally locked it as
                         * read-only. Both modifications on the given image
                         * are under text_mutex to avoid interference.
                         */
                        ret = __bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, NULL,
                                                   (u8 *)target->bpf_func +
                                                   poke->adj_off, false);
                        BUG_ON(ret < 0);
                }
                WRITE_ONCE(poke->ip_stable, true);
                mutex_unlock(&array->aux->poke_mutex);
        }
}

static void emit_mov_imm32(u8 **pprog, bool sign_propagate,
                           u32 dst_reg, const u32 imm32)
{
        u8 *prog = *pprog;
        u8 b1, b2, b3;
        int cnt = 0;

        /*
         * Optimization: if imm32 is positive, use 'mov %eax, imm32'
         * (which zero-extends imm32) to save 2 bytes.
         */
        if (sign_propagate && (s32)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);
                goto done;
        }

        /*
         * Optimization: if imm32 is zero, use 'xor %eax, %eax'
         * 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));
                goto done;
        }

        /* mov %eax, imm32 */
        if (is_ereg(dst_reg))
                EMIT1(add_1mod(0x40, dst_reg));
        EMIT1_off32(add_1reg(0xB8, dst_reg), imm32);
done:
        *pprog = prog;
}

static void emit_mov_imm64(u8 **pprog, u32 dst_reg,
                           const u32 imm32_hi, const u32 imm32_lo)
{
        u8 *prog = *pprog;
        int cnt = 0;

        if (is_uimm32(((u64)imm32_hi << 32) | (u32)imm32_lo)) {
                /*
                 * For emitting plain u32, where sign bit must not be
                 * propagated LLVM tends to load imm64 over mov32
                 * directly, so save couple of bytes by just doing
                 * 'mov %eax, imm32' instead.
                 */
                emit_mov_imm32(&prog, false, dst_reg, imm32_lo);
        } else {
                /* movabsq %rax, imm64 */
                EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg));
                EMIT(imm32_lo, 4);
                EMIT(imm32_hi, 4);
        }

        *pprog = prog;
}

static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg)
{
        u8 *prog = *pprog;
        int cnt = 0;

        if (is64) {
                /* mov dst, src */
                EMIT_mov(dst_reg, src_reg);
        } else {
                /* mov32 dst, src */
                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));
        }

        *pprog = prog;
}

/* LDX: dst_reg = *(u8*)(src_reg + off) */
static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
{
        u8 *prog = *pprog;
        int cnt = 0;

        switch (size) {
        case BPF_B:
                /* Emit 'movzx rax, byte ptr [rax + off]' */
                EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6);
                break;
        case BPF_H:
                /* Emit 'movzx rax, word ptr [rax + off]' */
                EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7);
                break;
        case 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);
                break;
        case BPF_DW:
                /* Emit 'mov rax, qword ptr [rax+0x14]' */
                EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B);
                break;
        }
        /*
         * 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(off))
                EMIT2(add_2reg(0x40, src_reg, dst_reg), off);
        else
                EMIT1_off32(add_2reg(0x80, src_reg, dst_reg), off);
        *pprog = prog;
}

/* STX: *(u8*)(dst_reg + off) = src_reg */
static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
{
        u8 *prog = *pprog;
        int cnt = 0;

        switch (size) {
        case BPF_B:
                /* Emit 'mov byte ptr [rax + off], al' */
                if (is_ereg(dst_reg) || is_ereg(src_reg) ||
                    /* We 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);
                break;
        case 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);
                break;
        case BPF_W:
                if (is_ereg(dst_reg) || is_ereg(src_reg))
                        EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89);
                else
                        EMIT1(0x89);
                break;
        case BPF_DW:
                EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89);
                break;
        }
        if (is_imm8(off))
                EMIT2(add_2reg(0x40, dst_reg, src_reg), off);
        else
                EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), off);
        *pprog = prog;
}

static bool ex_handler_bpf(const struct exception_table_entry *x,
                           struct pt_regs *regs, int trapnr,
                           unsigned long error_code, unsigned long fault_addr)
{
        u32 reg = x->fixup >> 8;

        /* jump over faulting load and clear dest register */
        *(unsigned long *)((void *)regs + reg) = 0;
        regs->ip += x->fixup & 0xff;
        return true;
}

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, excnt = 0;
        int proglen = 0;
        u8 *prog = temp;

        emit_prologue(&prog, bpf_prog->aux->stack_depth,
                      bpf_prog_was_classic(bpf_prog));
        addrs[0] = prog - temp;

        for (i = 1; i <= insn_cnt; i++, insn++) {
                const s32 imm32 = insn->imm;
                u32 dst_reg = insn->dst_reg;
                u32 src_reg = insn->src_reg;
                u8 b2 = 0, b3 = 0;
                s64 jmp_offset;
                u8 jmp_cond;
                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;

                case BPF_ALU64 | BPF_MOV | BPF_X:
                case BPF_ALU | BPF_MOV | BPF_X:
                        emit_mov_reg(&prog,
                                     BPF_CLASS(insn->code) == BPF_ALU64,
                                     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));

                        /*
                         * b3 holds 'normal' opcode, b2 short form only valid
                         * in case dst is eax/rax.
                         */
                        switch (BPF_OP(insn->code)) {
                        case BPF_ADD:
                                b3 = 0xC0;
                                b2 = 0x05;
                                break;
                        case BPF_SUB:
                                b3 = 0xE8;
                                b2 = 0x2D;
                                break;
                        case BPF_AND:
                                b3 = 0xE0;
                                b2 = 0x25;
                                break;
                        case BPF_OR:
                                b3 = 0xC8;
                                b2 = 0x0D;
                                break;
                        case BPF_XOR:
                                b3 = 0xF0;
                                b2 = 0x35;
                                break;
                        }

                        if (is_imm8(imm32))
                                EMIT3(0x83, add_1reg(b3, dst_reg), imm32);
                        else if (is_axreg(dst_reg))
                                EMIT1_off32(b2, imm32);
                        else
                                EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32);
                        break;

                case BPF_ALU64 | BPF_MOV | BPF_K:
                case BPF_ALU | BPF_MOV | BPF_K:
                        emit_mov_imm32(&prog, BPF_CLASS(insn->code) == BPF_ALU64,
                                       dst_reg, imm32);
                        break;

                case BPF_LD | BPF_IMM | BPF_DW:
                        emit_mov_imm64(&prog, dst_reg, insn[1].imm, insn[0].imm);
                        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_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:
                {
                        bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;

                        if (dst_reg != BPF_REG_0)
                                EMIT1(0x50); /* push rax */
                        if (dst_reg != BPF_REG_3)
                                EMIT1(0x52); /* push rdx */

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

                        if (BPF_SRC(insn->code) == BPF_X)
                                emit_mov_reg(&prog, is64, BPF_REG_0, src_reg);
                        else
                                emit_mov_imm32(&prog, is64, BPF_REG_0, imm32);

                        if (is64)
                                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));

                        if (dst_reg != BPF_REG_3)
                                EMIT1(0x5A); /* pop rdx */
                        if (dst_reg != BPF_REG_0) {
                                /* mov dst_reg, rax */
                                EMIT_mov(dst_reg, BPF_REG_0);
                                EMIT1(0x58); /* pop rax */
                        }
                        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;
                        }

                        if (imm32 == 1)
                                EMIT2(0xD1, add_1reg(b3, dst_reg));
                        else
                                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:
                case BPF_STX | BPF_MEM | BPF_H:
                case BPF_STX | BPF_MEM | BPF_W:
                case BPF_STX | BPF_MEM | BPF_DW:
                        emit_stx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
                        break;

                        /* LDX: dst_reg = *(u8*)(src_reg + off) */
                case BPF_LDX | BPF_MEM | BPF_B:
                case BPF_LDX | BPF_PROBE_MEM | BPF_B:
                case BPF_LDX | BPF_MEM | BPF_H:
                case BPF_LDX | BPF_PROBE_MEM | BPF_H:
                case BPF_LDX | BPF_MEM | BPF_W:
                case BPF_LDX | BPF_PROBE_MEM | BPF_W:
                case BPF_LDX | BPF_MEM | BPF_DW:
                case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
                        emit_ldx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
                        if (BPF_MODE(insn->code) == BPF_PROBE_MEM) {
                                struct exception_table_entry *ex;
                                u8 *_insn = image + proglen;
                                s64 delta;

                                if (!bpf_prog->aux->extable)
                                        break;

                                if (excnt >= bpf_prog->aux->num_exentries) {
                                        pr_err("ex gen bug\n");
                                        return -EFAULT;
                                }
                                ex = &bpf_prog->aux->extable[excnt++];

                                delta = _insn - (u8 *)&ex->insn;
                                if (!is_simm32(delta)) {
                                        pr_err("extable->insn doesn't fit into 32-bit\n");
                                        return -EFAULT;
                                }
                                ex->insn = delta;

                                delta = (u8 *)ex_handler_bpf - (u8 *)&ex->handler;
                                if (!is_simm32(delta)) {
                                        pr_err("extable->handler doesn't fit into 32-bit\n");
                                        return -EFAULT;
                                }
                                ex->handler = delta;

                                if (dst_reg > BPF_REG_9) {
                                        pr_err("verifier error\n");
                                        return -EFAULT;
                                }
                                /*
                                 * Compute size of x86 insn and its target dest x86 register.
                                 * ex_handler_bpf() will use lower 8 bits to adjust
                                 * pt_regs->ip to jump over this x86 instruction
                                 * and upper bits to figure out which pt_regs to zero out.
                                 * End result: x86 insn "mov rbx, qword ptr [rax+0x14]"
                                 * of 4 bytes will be ignored and rbx will be zero inited.
                                 */
                                ex->fixup = (prog - temp) | (reg2pt_regs[dst_reg] << 8);
                        }
                        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;
                        if (!imm32 || emit_call(&prog, func, image + addrs[i - 1]))
                                return -EINVAL;
                        break;

                case BPF_JMP | BPF_TAIL_CALL:
                        if (imm32)
                                emit_bpf_tail_call_direct(&bpf_prog->aux->poke_tab[imm32 - 1],
                                                          &prog, addrs[i], image);
                        else
                                emit_bpf_tail_call_indirect(&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_JSLT | BPF_X:
                case BPF_JMP | BPF_JSGE | BPF_X:
                case BPF_JMP | BPF_JSLE | BPF_X:
                case BPF_JMP32 | BPF_JEQ | BPF_X:
                case BPF_JMP32 | BPF_JNE | BPF_X:
                case BPF_JMP32 | BPF_JGT | BPF_X:
                case BPF_JMP32 | BPF_JLT | BPF_X:
                case BPF_JMP32 | BPF_JGE | BPF_X:
                case BPF_JMP32 | BPF_JLE | BPF_X:
                case BPF_JMP32 | BPF_JSGT | BPF_X:
                case BPF_JMP32 | BPF_JSLT | BPF_X:
                case BPF_JMP32 | BPF_JSGE | BPF_X:
                case BPF_JMP32 | BPF_JSLE | BPF_X:
                        /* cmp dst_reg, src_reg */
                        if (BPF_CLASS(insn->code) == BPF_JMP)
                                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(0x39, add_2reg(0xC0, dst_reg, src_reg));
                        goto emit_cond_jmp;

                case BPF_JMP | BPF_JSET | BPF_X:
                case BPF_JMP32 | BPF_JSET | BPF_X:
                        /* test dst_reg, src_reg */
                        if (BPF_CLASS(insn->code) == BPF_JMP)
                                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(0x85, add_2reg(0xC0, dst_reg, src_reg));
                        goto emit_cond_jmp;

                case BPF_JMP | BPF_JSET | BPF_K:
                case BPF_JMP32 | BPF_JSET | BPF_K:
                        /* test dst_reg, imm32 */
                        if (BPF_CLASS(insn->code) == BPF_JMP)
                                EMIT1(add_1mod(0x48, dst_reg));
                        else if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, 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_JLT | BPF_K:
                case BPF_JMP | BPF_JGE | BPF_K:
                case BPF_JMP | BPF_JLE | BPF_K:
                case BPF_JMP | BPF_JSGT | BPF_K:
                case BPF_JMP | BPF_JSLT | BPF_K:
                case BPF_JMP | BPF_JSGE | BPF_K:
                case BPF_JMP | BPF_JSLE | BPF_K:
                case BPF_JMP32 | BPF_JEQ | BPF_K:
                case BPF_JMP32 | BPF_JNE | BPF_K:
                case BPF_JMP32 | BPF_JGT | BPF_K:
                case BPF_JMP32 | BPF_JLT | BPF_K:
                case BPF_JMP32 | BPF_JGE | BPF_K:
                case BPF_JMP32 | BPF_JLE | BPF_K:
                case BPF_JMP32 | BPF_JSGT | BPF_K:
                case BPF_JMP32 | BPF_JSLT | BPF_K:
                case BPF_JMP32 | BPF_JSGE | BPF_K:
                case BPF_JMP32 | BPF_JSLE | BPF_K:
                        /* test dst_reg, dst_reg to save one extra byte */
                        if (imm32 == 0) {
                                if (BPF_CLASS(insn->code) == BPF_JMP)
                                        EMIT1(add_2mod(0x48, dst_reg, dst_reg));
                                else if (is_ereg(dst_reg))
                                        EMIT1(add_2mod(0x40, dst_reg, dst_reg));
                                EMIT2(0x85, add_2reg(0xC0, dst_reg, dst_reg));
                                goto emit_cond_jmp;
                        }

                        /* cmp dst_reg, imm8/32 */
                        if (BPF_CLASS(insn->code) == BPF_JMP)
                                EMIT1(add_1mod(0x48, dst_reg));
                        else if (is_ereg(dst_reg))
                                EMIT1(add_1mod(0x40, 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_JLT:
                                /* LT is unsigned '<', JB in x86 */
                                jmp_cond = X86_JB;
                                break;
                        case BPF_JGE:
                                /* GE is unsigned '>=', JAE in x86 */
                                jmp_cond = X86_JAE;
                                break;
                        case BPF_JLE:
                                /* LE is unsigned '<=', JBE in x86 */
                                jmp_cond = X86_JBE;
                                break;
                        case BPF_JSGT:
                                /* Signed '>', GT in x86 */
                                jmp_cond = X86_JG;
                                break;
                        case BPF_JSLT:
                                /* Signed '<', LT in x86 */
                                jmp_cond = X86_JL;
                                break;
                        case BPF_JSGE:
                                /* Signed '>=', GE in x86 */
                                jmp_cond = X86_JGE;
                                break;
                        case BPF_JSLE:
                                /* Signed '<=', LE in x86 */
                                jmp_cond = X86_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;

                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;
                        if (!bpf_prog_was_classic(bpf_prog))
                                EMIT1(0x5B); /* get rid of tail_call_cnt */
                        EMIT2(0x41, 0x5F);   /* pop r15 */
                        EMIT2(0x41, 0x5E);   /* pop r14 */
                        EMIT2(0x41, 0x5D);   /* pop r13 */
                        EMIT1(0x5B);         /* pop rbx */
                        EMIT1(0xC9);         /* leave */
                        EMIT1(0xC3);         /* ret */
                        break;

                default:
                        /*
                         * By design x86-64 JIT should support all BPF instructions.
                         * This error will be seen if new instruction was added
                         * to the interpreter, but not to the 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: 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;
        }

        if (image && excnt != bpf_prog->aux->num_exentries) {
                pr_err("extable is not populated\n");
                return -EFAULT;
        }
        return proglen;
}

static void save_regs(struct btf_func_model *m, u8 **prog, int nr_args,
                      int stack_size)
{
        int i;
        /* Store function arguments to stack.
         * For a function that accepts two pointers the sequence will be:
         * mov QWORD PTR [rbp-0x10],rdi
         * mov QWORD PTR [rbp-0x8],rsi
         */
        for (i = 0; i < min(nr_args, 6); i++)
                emit_stx(prog, bytes_to_bpf_size(m->arg_size[i]),
                         BPF_REG_FP,
                         i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
                         -(stack_size - i * 8));
}

static void restore_regs(struct btf_func_model *m, u8 **prog, int nr_args,
                         int stack_size)
{
        int i;

        /* Restore function arguments from stack.
         * For a function that accepts two pointers the sequence will be:
         * EMIT4(0x48, 0x8B, 0x7D, 0xF0); mov rdi,QWORD PTR [rbp-0x10]
         * EMIT4(0x48, 0x8B, 0x75, 0xF8); mov rsi,QWORD PTR [rbp-0x8]
         */
        for (i = 0; i < min(nr_args, 6); i++)
                emit_ldx(prog, bytes_to_bpf_size(m->arg_size[i]),
                         i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
                         BPF_REG_FP,
                         -(stack_size - i * 8));
}

static int invoke_bpf(struct btf_func_model *m, u8 **pprog,
                      struct bpf_prog **progs, int prog_cnt, int stack_size)
{
        u8 *prog = *pprog;
        int cnt = 0, i;

        for (i = 0; i < prog_cnt; i++) {
                if (emit_call(&prog, __bpf_prog_enter, prog))
                        return -EINVAL;
                /* remember prog start time returned by __bpf_prog_enter */
                emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0);

                /* arg1: lea rdi, [rbp - stack_size] */
                EMIT4(0x48, 0x8D, 0x7D, -stack_size);
                /* arg2: progs[i]->insnsi for interpreter */
                if (!progs[i]->jited)
                        emit_mov_imm64(&prog, BPF_REG_2,
                                       (long) progs[i]->insnsi >> 32,
                                       (u32) (long) progs[i]->insnsi);
                /* call JITed bpf program or interpreter */
                if (emit_call(&prog, progs[i]->bpf_func, prog))
                        return -EINVAL;

                /* arg1: mov rdi, progs[i] */
                emit_mov_imm64(&prog, BPF_REG_1, (long) progs[i] >> 32,
                               (u32) (long) progs[i]);
                /* arg2: mov rsi, rbx <- start time in nsec */
                emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6);
                if (emit_call(&prog, __bpf_prog_exit, prog))
                        return -EINVAL;
        }
        *pprog = prog;
        return 0;
}

/* Example:
 * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
 * its 'struct btf_func_model' will be nr_args=2
 * The assembly code when eth_type_trans is executing after trampoline:
 *
 * push rbp
 * mov rbp, rsp
 * sub rsp, 16                     // space for skb and dev
 * push rbx                        // temp regs to pass start time
 * mov qword ptr [rbp - 16], rdi   // save skb pointer to stack
 * mov qword ptr [rbp - 8], rsi    // save dev pointer to stack
 * call __bpf_prog_enter           // rcu_read_lock and preempt_disable
 * mov rbx, rax                    // remember start time in bpf stats are enabled
 * lea rdi, [rbp - 16]             // R1==ctx of bpf prog
 * call addr_of_jited_FENTRY_prog
 * movabsq rdi, 64bit_addr_of_struct_bpf_prog  // unused if bpf stats are off
 * mov rsi, rbx                    // prog start time
 * call __bpf_prog_exit            // rcu_read_unlock, preempt_enable and stats math
 * mov rdi, qword ptr [rbp - 16]   // restore skb pointer from stack
 * mov rsi, qword ptr [rbp - 8]    // restore dev pointer from stack
 * pop rbx
 * leave
 * ret
 *
 * eth_type_trans has 5 byte nop at the beginning. These 5 bytes will be
 * replaced with 'call generated_bpf_trampoline'. When it returns
 * eth_type_trans will continue executing with original skb and dev pointers.
 *
 * The assembly code when eth_type_trans is called from trampoline:
 *
 * push rbp
 * mov rbp, rsp
 * sub rsp, 24                     // space for skb, dev, return value
 * push rbx                        // temp regs to pass start time
 * mov qword ptr [rbp - 24], rdi   // save skb pointer to stack
 * mov qword ptr [rbp - 16], rsi   // save dev pointer to stack
 * call __bpf_prog_enter           // rcu_read_lock and preempt_disable
 * mov rbx, rax                    // remember start time if bpf stats are enabled
 * lea rdi, [rbp - 24]             // R1==ctx of bpf prog
 * call addr_of_jited_FENTRY_prog  // bpf prog can access skb and dev
 * movabsq rdi, 64bit_addr_of_struct_bpf_prog  // unused if bpf stats are off
 * mov rsi, rbx                    // prog start time
 * call __bpf_prog_exit            // rcu_read_unlock, preempt_enable and stats math
 * mov rdi, qword ptr [rbp - 24]   // restore skb pointer from stack
 * mov rsi, qword ptr [rbp - 16]   // restore dev pointer from stack
 * call eth_type_trans+5           // execute body of eth_type_trans
 * mov qword ptr [rbp - 8], rax    // save return value
 * call __bpf_prog_enter           // rcu_read_lock and preempt_disable
 * mov rbx, rax                    // remember start time in bpf stats are enabled
 * lea rdi, [rbp - 24]             // R1==ctx of bpf prog
 * call addr_of_jited_FEXIT_prog   // bpf prog can access skb, dev, return value
 * movabsq rdi, 64bit_addr_of_struct_bpf_prog  // unused if bpf stats are off
 * mov rsi, rbx                    // prog start time
 * call __bpf_prog_exit            // rcu_read_unlock, preempt_enable and stats math
 * mov rax, qword ptr [rbp - 8]    // restore eth_type_trans's return value
 * pop rbx
 * leave
 * add rsp, 8                      // skip eth_type_trans's frame
 * ret                             // return to its caller
 */
int arch_prepare_bpf_trampoline(void *image, struct btf_func_model *m, u32 flags,
                                struct bpf_prog **fentry_progs, int fentry_cnt,
                                struct bpf_prog **fexit_progs, int fexit_cnt,
                                void *orig_call)
{
        int cnt = 0, nr_args = m->nr_args;
        int stack_size = nr_args * 8;
        u8 *prog;

        /* x86-64 supports up to 6 arguments. 7+ can be added in the future */
        if (nr_args > 6)
                return -ENOTSUPP;

        if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
            (flags & BPF_TRAMP_F_SKIP_FRAME))
                return -EINVAL;

        if (flags & BPF_TRAMP_F_CALL_ORIG)
                stack_size += 8; /* room for return value of orig_call */

        if (flags & BPF_TRAMP_F_SKIP_FRAME)
                /* skip patched call instruction and point orig_call to actual
                 * body of the kernel function.
                 */
                orig_call += X86_PATCH_SIZE;

        prog = image;

        EMIT1(0x55);             /* push rbp */
        EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
        EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */
        EMIT1(0x53);             /* push rbx */

        save_regs(m, &prog, nr_args, stack_size);

        if (fentry_cnt)
                if (invoke_bpf(m, &prog, fentry_progs, fentry_cnt, stack_size))
                        return -EINVAL;

        if (flags & BPF_TRAMP_F_CALL_ORIG) {
                if (fentry_cnt)
                        restore_regs(m, &prog, nr_args, stack_size);

                /* call original function */
                if (emit_call(&prog, orig_call, prog))
                        return -EINVAL;
                /* remember return value in a stack for bpf prog to access */
                emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
        }

        if (fexit_cnt)
                if (invoke_bpf(m, &prog, fexit_progs, fexit_cnt, stack_size))
                        return -EINVAL;

        if (flags & BPF_TRAMP_F_RESTORE_REGS)
                restore_regs(m, &prog, nr_args, stack_size);

        if (flags & BPF_TRAMP_F_CALL_ORIG)
                /* restore original return value back into RAX */
                emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);

        EMIT1(0x5B); /* pop rbx */
        EMIT1(0xC9); /* leave */
        if (flags & BPF_TRAMP_F_SKIP_FRAME)
                /* skip our return address and return to parent */
                EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */
        EMIT1(0xC3); /* ret */
        /* One half of the page has active running trampoline.
         * Another half is an area for next trampoline.
         * Make sure the trampoline generation logic doesn't overflow.
         */
        if (WARN_ON_ONCE(prog - (u8 *)image > PAGE_SIZE / 2 - BPF_INSN_SAFETY))
                return -EFAULT;
        return 0;
}

struct x64_jit_data {
        struct bpf_binary_header *header;
        int *addrs;
        u8 *image;
        int proglen;
        struct jit_context ctx;
};

struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
        struct bpf_binary_header *header = NULL;
        struct bpf_prog *tmp, *orig_prog = prog;
        struct x64_jit_data *jit_data;
        int proglen, oldproglen = 0;
        struct jit_context ctx = {};
        bool tmp_blinded = false;
        bool extra_pass = 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;
        }

        jit_data = prog->aux->jit_data;
        if (!jit_data) {
                jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
                if (!jit_data) {
                        prog = orig_prog;
                        goto out;
                }
                prog->aux->jit_data = jit_data;
        }
        addrs = jit_data->addrs;
        if (addrs) {
                ctx = jit_data->ctx;
                oldproglen = jit_data->proglen;
                image = jit_data->image;
                header = jit_data->header;
                extra_pass = true;
                goto skip_init_addrs;
        }
        addrs = kmalloc_array(prog->len + 1, sizeof(*addrs), GFP_KERNEL);
        if (!addrs) {
                prog = orig_prog;
                goto out_addrs;
        }

        /*
         * 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;
skip_init_addrs:

        /*
         * 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) {
                        /*
                         * The number of entries in extable is the number of BPF_LDX
                         * insns that access kernel memory via "pointer to BTF type".
                         * The verifier changed their opcode from LDX|MEM|size
                         * to LDX|PROBE_MEM|size to make JITing easier.
                         */
                        u32 align = __alignof__(struct exception_table_entry);
                        u32 extable_size = prog->aux->num_exentries *
                                sizeof(struct exception_table_entry);

                        /* allocate module memory for x86 insns and extable */
                        header = bpf_jit_binary_alloc(roundup(proglen, align) + extable_size,
                                                      &image, align, jit_fill_hole);
                        if (!header) {
                                prog = orig_prog;
                                goto out_addrs;
                        }
                        prog->aux->extable = (void *) image + roundup(proglen, align);
                }
                oldproglen = proglen;
                cond_resched();
        }

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

        if (image) {
                if (!prog->is_func || extra_pass) {
                        bpf_tail_call_direct_fixup(prog);
                        bpf_jit_binary_lock_ro(header);
                } else {
                        jit_data->addrs = addrs;
                        jit_data->ctx = ctx;
                        jit_data->proglen = proglen;
                        jit_data->image = image;
                        jit_data->header = header;
                }
                prog->bpf_func = (void *)image;
                prog->jited = 1;
                prog->jited_len = proglen;
        } else {
                prog = orig_prog;
        }

        if (!image || !prog->is_func || extra_pass) {
                if (image)
                        bpf_prog_fill_jited_linfo(prog, addrs + 1);
out_addrs:
                kfree(addrs);
                kfree(jit_data);
                prog->aux->jit_data = NULL;
        }
out:
        if (tmp_blinded)
                bpf_jit_prog_release_other(prog, prog == orig_prog ?
                                           tmp : orig_prog);
        return prog;
}