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bpf_jit_x86.c
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bpf_jit_x86.c
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/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2018 Intel Corporation
*/
#include <stdarg.h>
#include <errno.h>
#include <stdint.h>
#include <inttypes.h>
#include <rte_common.h>
#include <rte_log.h>
#include <rte_debug.h>
#include <rte_memory.h>
#include <rte_eal.h>
#include <rte_byteorder.h>
#include "bpf_impl.h"
#define GET_BPF_OP(op) (BPF_OP(op) >> 4)
enum {
RAX = 0, /* scratch, return value */
RCX = 1, /* scratch, 4th arg */
RDX = 2, /* scratch, 3rd arg */
RBX = 3, /* callee saved */
RSP = 4, /* stack pointer */
RBP = 5, /* frame pointer, callee saved */
RSI = 6, /* scratch, 2nd arg */
RDI = 7, /* scratch, 1st arg */
R8 = 8, /* scratch, 5th arg */
R9 = 9, /* scratch, 6th arg */
R10 = 10, /* scratch */
R11 = 11, /* scratch */
R12 = 12, /* callee saved */
R13 = 13, /* callee saved */
R14 = 14, /* callee saved */
R15 = 15, /* callee saved */
};
#define IS_EXT_REG(r) ((r) >= R8)
enum {
REX_PREFIX = 0x40, /* fixed value 0100 */
REX_W = 0x8, /* 64bit operand size */
REX_R = 0x4, /* extension of the ModRM.reg field */
REX_X = 0x2, /* extension of the SIB.index field */
REX_B = 0x1, /* extension of the ModRM.rm field */
};
enum {
MOD_INDIRECT = 0,
MOD_IDISP8 = 1,
MOD_IDISP32 = 2,
MOD_DIRECT = 3,
};
enum {
SIB_SCALE_1 = 0,
SIB_SCALE_2 = 1,
SIB_SCALE_4 = 2,
SIB_SCALE_8 = 3,
};
/*
* eBPF to x86_64 register mappings.
*/
static const uint32_t ebpf2x86[] = {
[EBPF_REG_0] = RAX,
[EBPF_REG_1] = RDI,
[EBPF_REG_2] = RSI,
[EBPF_REG_3] = RDX,
[EBPF_REG_4] = RCX,
[EBPF_REG_5] = R8,
[EBPF_REG_6] = RBX,
[EBPF_REG_7] = R13,
[EBPF_REG_8] = R14,
[EBPF_REG_9] = R15,
[EBPF_REG_10] = RBP,
};
/*
* r10 and r11 are used as a scratch temporary registers.
*/
enum {
REG_DIV_IMM = R9,
REG_TMP0 = R11,
REG_TMP1 = R10,
};
/* LD_ABS/LD_IMM offsets */
enum {
LDMB_FSP_OFS, /* fast-path */
LDMB_SLP_OFS, /* slow-path */
LDMB_FIN_OFS, /* final part */
LDMB_OFS_NUM
};
/*
* callee saved registers list.
* keep RBP as the last one.
*/
static const uint32_t save_regs[] = {RBX, R12, R13, R14, R15, RBP};
struct bpf_jit_state {
uint32_t idx;
size_t sz;
struct {
uint32_t num;
int32_t off;
} exit;
struct {
uint32_t stack_ofs;
} ldmb;
uint32_t reguse;
int32_t *off;
uint8_t *ins;
};
#define INUSE(v, r) (((v) >> (r)) & 1)
#define USED(v, r) ((v) |= 1 << (r))
union bpf_jit_imm {
uint32_t u32;
uint8_t u8[4];
};
/*
* In many cases for imm8 we can produce shorter code.
*/
static size_t
imm_size(int32_t v)
{
if (v == (int8_t)v)
return sizeof(int8_t);
return sizeof(int32_t);
}
static void
emit_bytes(struct bpf_jit_state *st, const uint8_t ins[], uint32_t sz)
{
uint32_t i;
if (st->ins != NULL) {
for (i = 0; i != sz; i++)
st->ins[st->sz + i] = ins[i];
}
st->sz += sz;
}
static void
emit_imm(struct bpf_jit_state *st, const uint32_t imm, uint32_t sz)
{
union bpf_jit_imm v;
v.u32 = imm;
emit_bytes(st, v.u8, sz);
}
/*
* emit REX byte
*/
static void
emit_rex(struct bpf_jit_state *st, uint32_t op, uint32_t reg, uint32_t rm)
{
uint8_t rex;
/* mark operand registers as used*/
USED(st->reguse, reg);
USED(st->reguse, rm);
rex = 0;
if (BPF_CLASS(op) == EBPF_ALU64 ||
op == (BPF_ST | BPF_MEM | EBPF_DW) ||
op == (BPF_STX | BPF_MEM | EBPF_DW) ||
op == (BPF_STX | EBPF_XADD | EBPF_DW) ||
op == (BPF_LD | BPF_IMM | EBPF_DW) ||
(BPF_CLASS(op) == BPF_LDX &&
BPF_MODE(op) == BPF_MEM &&
BPF_SIZE(op) != BPF_W))
rex |= REX_W;
if (IS_EXT_REG(reg))
rex |= REX_R;
if (IS_EXT_REG(rm))
rex |= REX_B;
/* store using SIL, DIL */
if (op == (BPF_STX | BPF_MEM | BPF_B) && (reg == RDI || reg == RSI))
rex |= REX_PREFIX;
if (rex != 0) {
rex |= REX_PREFIX;
emit_bytes(st, &rex, sizeof(rex));
}
}
/*
* emit MODRegRM byte
*/
static void
emit_modregrm(struct bpf_jit_state *st, uint32_t mod, uint32_t reg, uint32_t rm)
{
uint8_t v;
v = mod << 6 | (reg & 7) << 3 | (rm & 7);
emit_bytes(st, &v, sizeof(v));
}
/*
* emit SIB byte
*/
static void
emit_sib(struct bpf_jit_state *st, uint32_t scale, uint32_t idx, uint32_t base)
{
uint8_t v;
v = scale << 6 | (idx & 7) << 3 | (base & 7);
emit_bytes(st, &v, sizeof(v));
}
/*
* emit OPCODE+REGIDX byte
*/
static void
emit_opcode(struct bpf_jit_state *st, uint8_t ops, uint32_t reg)
{
uint8_t v;
v = ops | (reg & 7);
emit_bytes(st, &v, sizeof(v));
}
/*
* emit xchg %<sreg>, %<dreg>
*/
static void
emit_xchg_reg(struct bpf_jit_state *st, uint32_t sreg, uint32_t dreg)
{
const uint8_t ops = 0x87;
emit_rex(st, EBPF_ALU64, sreg, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, sreg, dreg);
}
/*
* emit neg %<dreg>
*/
static void
emit_neg(struct bpf_jit_state *st, uint32_t op, uint32_t dreg)
{
const uint8_t ops = 0xF7;
const uint8_t mods = 3;
emit_rex(st, op, 0, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, dreg);
}
/*
* emit mov %<sreg>, %<dreg>
*/
static void
emit_mov_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg)
{
const uint8_t ops = 0x89;
/* if operands are 32-bit, then it can be used to clear upper 32-bit */
if (sreg != dreg || BPF_CLASS(op) == BPF_ALU) {
emit_rex(st, op, sreg, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, sreg, dreg);
}
}
/*
* emit movzwl %<sreg>, %<dreg>
*/
static void
emit_movzwl(struct bpf_jit_state *st, uint32_t sreg, uint32_t dreg)
{
static const uint8_t ops[] = {0x0F, 0xB7};
emit_rex(st, BPF_ALU, sreg, dreg);
emit_bytes(st, ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, sreg, dreg);
}
/*
* emit ror <imm8>, %<dreg>
*/
static void
emit_ror_imm(struct bpf_jit_state *st, uint32_t dreg, uint32_t imm)
{
const uint8_t prfx = 0x66;
const uint8_t ops = 0xC1;
const uint8_t mods = 1;
emit_bytes(st, &prfx, sizeof(prfx));
emit_rex(st, BPF_ALU, 0, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, dreg);
emit_imm(st, imm, imm_size(imm));
}
/*
* emit bswap %<dreg>
*/
static void
emit_be2le_48(struct bpf_jit_state *st, uint32_t dreg, uint32_t imm)
{
uint32_t rop;
const uint8_t ops = 0x0F;
const uint8_t mods = 1;
rop = (imm == 64) ? EBPF_ALU64 : BPF_ALU;
emit_rex(st, rop, 0, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, dreg);
}
static void
emit_be2le(struct bpf_jit_state *st, uint32_t dreg, uint32_t imm)
{
if (imm == 16) {
emit_ror_imm(st, dreg, 8);
emit_movzwl(st, dreg, dreg);
} else
emit_be2le_48(st, dreg, imm);
}
/*
* In general it is NOP for x86.
* Just clear the upper bits.
*/
static void
emit_le2be(struct bpf_jit_state *st, uint32_t dreg, uint32_t imm)
{
if (imm == 16)
emit_movzwl(st, dreg, dreg);
else if (imm == 32)
emit_mov_reg(st, BPF_ALU | EBPF_MOV | BPF_X, dreg, dreg);
}
/*
* emit one of:
* add <imm>, %<dreg>
* and <imm>, %<dreg>
* or <imm>, %<dreg>
* sub <imm>, %<dreg>
* xor <imm>, %<dreg>
*/
static void
emit_alu_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg, uint32_t imm)
{
uint8_t mod, opcode;
uint32_t bop, imsz;
const uint8_t op8 = 0x83;
const uint8_t op32 = 0x81;
static const uint8_t mods[] = {
[GET_BPF_OP(BPF_ADD)] = 0,
[GET_BPF_OP(BPF_AND)] = 4,
[GET_BPF_OP(BPF_OR)] = 1,
[GET_BPF_OP(BPF_SUB)] = 5,
[GET_BPF_OP(BPF_XOR)] = 6,
};
bop = GET_BPF_OP(op);
mod = mods[bop];
imsz = imm_size(imm);
opcode = (imsz == 1) ? op8 : op32;
emit_rex(st, op, 0, dreg);
emit_bytes(st, &opcode, sizeof(opcode));
emit_modregrm(st, MOD_DIRECT, mod, dreg);
emit_imm(st, imm, imsz);
}
/*
* emit one of:
* add %<sreg>, %<dreg>
* and %<sreg>, %<dreg>
* or %<sreg>, %<dreg>
* sub %<sreg>, %<dreg>
* xor %<sreg>, %<dreg>
*/
static void
emit_alu_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg)
{
uint32_t bop;
static const uint8_t ops[] = {
[GET_BPF_OP(BPF_ADD)] = 0x01,
[GET_BPF_OP(BPF_AND)] = 0x21,
[GET_BPF_OP(BPF_OR)] = 0x09,
[GET_BPF_OP(BPF_SUB)] = 0x29,
[GET_BPF_OP(BPF_XOR)] = 0x31,
};
bop = GET_BPF_OP(op);
emit_rex(st, op, sreg, dreg);
emit_bytes(st, &ops[bop], sizeof(ops[bop]));
emit_modregrm(st, MOD_DIRECT, sreg, dreg);
}
static void
emit_shift(struct bpf_jit_state *st, uint32_t op, uint32_t dreg)
{
uint8_t mod;
uint32_t bop, opx;
static const uint8_t ops[] = {0xC1, 0xD3};
static const uint8_t mods[] = {
[GET_BPF_OP(BPF_LSH)] = 4,
[GET_BPF_OP(BPF_RSH)] = 5,
[GET_BPF_OP(EBPF_ARSH)] = 7,
};
bop = GET_BPF_OP(op);
mod = mods[bop];
opx = (BPF_SRC(op) == BPF_X);
emit_rex(st, op, 0, dreg);
emit_bytes(st, &ops[opx], sizeof(ops[opx]));
emit_modregrm(st, MOD_DIRECT, mod, dreg);
}
/*
* emit one of:
* shl <imm>, %<dreg>
* shr <imm>, %<dreg>
* sar <imm>, %<dreg>
*/
static void
emit_shift_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg,
uint32_t imm)
{
emit_shift(st, op, dreg);
emit_imm(st, imm, imm_size(imm));
}
/*
* emit one of:
* shl %<dreg>
* shr %<dreg>
* sar %<dreg>
* note that rcx is implicitly used as a source register, so few extra
* instructions for register spillage might be necessary.
*/
static void
emit_shift_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg)
{
if (sreg != RCX)
emit_xchg_reg(st, RCX, sreg);
emit_shift(st, op, (dreg == RCX) ? sreg : dreg);
if (sreg != RCX)
emit_xchg_reg(st, RCX, sreg);
}
/*
* emit mov <imm>, %<dreg>
*/
static void
emit_mov_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg, uint32_t imm)
{
const uint8_t ops = 0xC7;
if (imm == 0) {
/* replace 'mov 0, %<dst>' with 'xor %<dst>, %<dst>' */
op = BPF_CLASS(op) | BPF_XOR | BPF_X;
emit_alu_reg(st, op, dreg, dreg);
return;
}
emit_rex(st, op, 0, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, 0, dreg);
emit_imm(st, imm, sizeof(imm));
}
/*
* emit mov <imm64>, %<dreg>
*/
static void
emit_ld_imm64(struct bpf_jit_state *st, uint32_t dreg, uint32_t imm0,
uint32_t imm1)
{
uint32_t op;
const uint8_t ops = 0xB8;
op = (imm1 == 0) ? BPF_ALU : EBPF_ALU64;
emit_rex(st, op, 0, dreg);
emit_opcode(st, ops, dreg);
emit_imm(st, imm0, sizeof(imm0));
if (imm1 != 0)
emit_imm(st, imm1, sizeof(imm1));
}
/*
* note that rax:rdx are implicitly used as source/destination registers,
* so some reg spillage is necessary.
* emit:
* mov %rax, %r11
* mov %rdx, %r10
* mov %<dreg>, %rax
* either:
* mov %<sreg>, %rdx
* OR
* mov <imm>, %rdx
* mul %rdx
* mov %r10, %rdx
* mov %rax, %<dreg>
* mov %r11, %rax
*/
static void
emit_mul(struct bpf_jit_state *st, uint32_t op, uint32_t sreg, uint32_t dreg,
uint32_t imm)
{
const uint8_t ops = 0xF7;
const uint8_t mods = 4;
/* save rax & rdx */
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X, RAX, REG_TMP0);
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X, RDX, REG_TMP1);
/* rax = dreg */
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X, dreg, RAX);
if (BPF_SRC(op) == BPF_X)
/* rdx = sreg */
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X,
sreg == RAX ? REG_TMP0 : sreg, RDX);
else
/* rdx = imm */
emit_mov_imm(st, EBPF_ALU64 | EBPF_MOV | BPF_K, RDX, imm);
emit_rex(st, op, RAX, RDX);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, RDX);
if (dreg != RDX)
/* restore rdx */
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X, REG_TMP1, RDX);
if (dreg != RAX) {
/* dreg = rax */
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X, RAX, dreg);
/* restore rax */
emit_mov_reg(st, EBPF_ALU64 | EBPF_MOV | BPF_X, REG_TMP0, RAX);
}
}
/*
* emit mov <ofs>(%<sreg>), %<dreg>
* note that for non 64-bit ops, higher bits have to be cleared.
*/
static void
emit_ld_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg, uint32_t dreg,
int32_t ofs)
{
uint32_t mods, opsz;
const uint8_t op32 = 0x8B;
const uint8_t op16[] = {0x0F, 0xB7};
const uint8_t op8[] = {0x0F, 0xB6};
emit_rex(st, op, dreg, sreg);
opsz = BPF_SIZE(op);
if (opsz == BPF_B)
emit_bytes(st, op8, sizeof(op8));
else if (opsz == BPF_H)
emit_bytes(st, op16, sizeof(op16));
else
emit_bytes(st, &op32, sizeof(op32));
mods = (imm_size(ofs) == 1) ? MOD_IDISP8 : MOD_IDISP32;
emit_modregrm(st, mods, dreg, sreg);
if (sreg == RSP || sreg == R12)
emit_sib(st, SIB_SCALE_1, sreg, sreg);
emit_imm(st, ofs, imm_size(ofs));
}
/*
* emit one of:
* mov %<sreg>, <ofs>(%<dreg>)
* mov <imm>, <ofs>(%<dreg>)
*/
static void
emit_st_common(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg, uint32_t imm, int32_t ofs)
{
uint32_t mods, imsz, opsz, opx;
const uint8_t prfx16 = 0x66;
/* 8 bit instruction opcodes */
static const uint8_t op8[] = {0xC6, 0x88};
/* 16/32/64 bit instruction opcodes */
static const uint8_t ops[] = {0xC7, 0x89};
/* is the instruction has immediate value or src reg? */
opx = (BPF_CLASS(op) == BPF_STX);
opsz = BPF_SIZE(op);
if (opsz == BPF_H)
emit_bytes(st, &prfx16, sizeof(prfx16));
emit_rex(st, op, sreg, dreg);
if (opsz == BPF_B)
emit_bytes(st, &op8[opx], sizeof(op8[opx]));
else
emit_bytes(st, &ops[opx], sizeof(ops[opx]));
imsz = imm_size(ofs);
mods = (imsz == 1) ? MOD_IDISP8 : MOD_IDISP32;
emit_modregrm(st, mods, sreg, dreg);
if (dreg == RSP || dreg == R12)
emit_sib(st, SIB_SCALE_1, dreg, dreg);
emit_imm(st, ofs, imsz);
if (opx == 0) {
imsz = RTE_MIN(bpf_size(opsz), sizeof(imm));
emit_imm(st, imm, imsz);
}
}
static void
emit_st_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg, uint32_t imm,
int32_t ofs)
{
emit_st_common(st, op, 0, dreg, imm, ofs);
}
static void
emit_st_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg, uint32_t dreg,
int32_t ofs)
{
emit_st_common(st, op, sreg, dreg, 0, ofs);
}
/*
* emit lock add %<sreg>, <ofs>(%<dreg>)
*/
static void
emit_st_xadd(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg, int32_t ofs)
{
uint32_t imsz, mods;
const uint8_t lck = 0xF0; /* lock prefix */
const uint8_t ops = 0x01; /* add opcode */
imsz = imm_size(ofs);
mods = (imsz == 1) ? MOD_IDISP8 : MOD_IDISP32;
emit_bytes(st, &lck, sizeof(lck));
emit_rex(st, op, sreg, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, mods, sreg, dreg);
emit_imm(st, ofs, imsz);
}
/*
* emit:
* mov <imm64>, (%rax)
* call *%rax
*/
static void
emit_call(struct bpf_jit_state *st, uintptr_t trg)
{
const uint8_t ops = 0xFF;
const uint8_t mods = 2;
emit_ld_imm64(st, RAX, trg, trg >> 32);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, RAX);
}
/*
* emit jmp <ofs>
* where 'ofs' is the target offset for the native code.
*/
static void
emit_abs_jmp(struct bpf_jit_state *st, int32_t ofs)
{
int32_t joff;
uint32_t imsz;
const uint8_t op8 = 0xEB;
const uint8_t op32 = 0xE9;
const int32_t sz8 = sizeof(op8) + sizeof(uint8_t);
const int32_t sz32 = sizeof(op32) + sizeof(uint32_t);
/* max possible jmp instruction size */
const int32_t iszm = RTE_MAX(sz8, sz32);
joff = ofs - st->sz;
imsz = RTE_MAX(imm_size(joff), imm_size(joff + iszm));
if (imsz == 1) {
emit_bytes(st, &op8, sizeof(op8));
joff -= sz8;
} else {
emit_bytes(st, &op32, sizeof(op32));
joff -= sz32;
}
emit_imm(st, joff, imsz);
}
/*
* emit jmp <ofs>
* where 'ofs' is the target offset for the BPF bytecode.
*/
static void
emit_jmp(struct bpf_jit_state *st, int32_t ofs)
{
emit_abs_jmp(st, st->off[st->idx + ofs]);
}
/*
* emit one of:
* cmovz %<sreg>, <%dreg>
* cmovne %<sreg>, <%dreg>
* cmova %<sreg>, <%dreg>
* cmovb %<sreg>, <%dreg>
* cmovae %<sreg>, <%dreg>
* cmovbe %<sreg>, <%dreg>
* cmovg %<sreg>, <%dreg>
* cmovl %<sreg>, <%dreg>
* cmovge %<sreg>, <%dreg>
* cmovle %<sreg>, <%dreg>
*/
static void
emit_movcc_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg)
{
uint32_t bop;
static const uint8_t ops[][2] = {
[GET_BPF_OP(BPF_JEQ)] = {0x0F, 0x44}, /* CMOVZ */
[GET_BPF_OP(EBPF_JNE)] = {0x0F, 0x45}, /* CMOVNE */
[GET_BPF_OP(BPF_JGT)] = {0x0F, 0x47}, /* CMOVA */
[GET_BPF_OP(EBPF_JLT)] = {0x0F, 0x42}, /* CMOVB */
[GET_BPF_OP(BPF_JGE)] = {0x0F, 0x43}, /* CMOVAE */
[GET_BPF_OP(EBPF_JLE)] = {0x0F, 0x46}, /* CMOVBE */
[GET_BPF_OP(EBPF_JSGT)] = {0x0F, 0x4F}, /* CMOVG */
[GET_BPF_OP(EBPF_JSLT)] = {0x0F, 0x4C}, /* CMOVL */
[GET_BPF_OP(EBPF_JSGE)] = {0x0F, 0x4D}, /* CMOVGE */
[GET_BPF_OP(EBPF_JSLE)] = {0x0F, 0x4E}, /* CMOVLE */
[GET_BPF_OP(BPF_JSET)] = {0x0F, 0x45}, /* CMOVNE */
};
bop = GET_BPF_OP(op);
emit_rex(st, op, dreg, sreg);
emit_bytes(st, ops[bop], sizeof(ops[bop]));
emit_modregrm(st, MOD_DIRECT, dreg, sreg);
}
/*
* emit one of:
* je <ofs>
* jne <ofs>
* ja <ofs>
* jb <ofs>
* jae <ofs>
* jbe <ofs>
* jg <ofs>
* jl <ofs>
* jge <ofs>
* jle <ofs>
* where 'ofs' is the target offset for the native code.
*/
static void
emit_abs_jcc(struct bpf_jit_state *st, uint32_t op, int32_t ofs)
{
uint32_t bop, imsz;
int32_t joff;
static const uint8_t op8[] = {
[GET_BPF_OP(BPF_JEQ)] = 0x74, /* JE */
[GET_BPF_OP(EBPF_JNE)] = 0x75, /* JNE */
[GET_BPF_OP(BPF_JGT)] = 0x77, /* JA */
[GET_BPF_OP(EBPF_JLT)] = 0x72, /* JB */
[GET_BPF_OP(BPF_JGE)] = 0x73, /* JAE */
[GET_BPF_OP(EBPF_JLE)] = 0x76, /* JBE */
[GET_BPF_OP(EBPF_JSGT)] = 0x7F, /* JG */
[GET_BPF_OP(EBPF_JSLT)] = 0x7C, /* JL */
[GET_BPF_OP(EBPF_JSGE)] = 0x7D, /*JGE */
[GET_BPF_OP(EBPF_JSLE)] = 0x7E, /* JLE */
[GET_BPF_OP(BPF_JSET)] = 0x75, /*JNE */
};
static const uint8_t op32[][2] = {
[GET_BPF_OP(BPF_JEQ)] = {0x0F, 0x84}, /* JE */
[GET_BPF_OP(EBPF_JNE)] = {0x0F, 0x85}, /* JNE */
[GET_BPF_OP(BPF_JGT)] = {0x0F, 0x87}, /* JA */
[GET_BPF_OP(EBPF_JLT)] = {0x0F, 0x82}, /* JB */
[GET_BPF_OP(BPF_JGE)] = {0x0F, 0x83}, /* JAE */
[GET_BPF_OP(EBPF_JLE)] = {0x0F, 0x86}, /* JBE */
[GET_BPF_OP(EBPF_JSGT)] = {0x0F, 0x8F}, /* JG */
[GET_BPF_OP(EBPF_JSLT)] = {0x0F, 0x8C}, /* JL */
[GET_BPF_OP(EBPF_JSGE)] = {0x0F, 0x8D}, /*JGE */
[GET_BPF_OP(EBPF_JSLE)] = {0x0F, 0x8E}, /* JLE */
[GET_BPF_OP(BPF_JSET)] = {0x0F, 0x85}, /*JNE */
};
const int32_t sz8 = sizeof(op8[0]) + sizeof(uint8_t);
const int32_t sz32 = sizeof(op32[0]) + sizeof(uint32_t);
/* max possible jcc instruction size */
const int32_t iszm = RTE_MAX(sz8, sz32);
joff = ofs - st->sz;
imsz = RTE_MAX(imm_size(joff), imm_size(joff + iszm));
bop = GET_BPF_OP(op);
if (imsz == 1) {
emit_bytes(st, &op8[bop], sizeof(op8[bop]));
joff -= sz8;
} else {
emit_bytes(st, op32[bop], sizeof(op32[bop]));
joff -= sz32;
}
emit_imm(st, joff, imsz);
}
/*
* emit one of:
* je <ofs>
* jne <ofs>
* ja <ofs>
* jb <ofs>
* jae <ofs>
* jbe <ofs>
* jg <ofs>
* jl <ofs>
* jge <ofs>
* jle <ofs>
* where 'ofs' is the target offset for the BPF bytecode.
*/
static void
emit_jcc(struct bpf_jit_state *st, uint32_t op, int32_t ofs)
{
emit_abs_jcc(st, op, st->off[st->idx + ofs]);
}
/*
* emit cmp <imm>, %<dreg>
*/
static void
emit_cmp_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg, uint32_t imm)
{
uint8_t ops;
uint32_t imsz;
const uint8_t op8 = 0x83;
const uint8_t op32 = 0x81;
const uint8_t mods = 7;
imsz = imm_size(imm);
ops = (imsz == 1) ? op8 : op32;
emit_rex(st, op, 0, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, dreg);
emit_imm(st, imm, imsz);
}
/*
* emit test <imm>, %<dreg>
*/
static void
emit_tst_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg, uint32_t imm)
{
const uint8_t ops = 0xF7;
const uint8_t mods = 0;
emit_rex(st, op, 0, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, mods, dreg);
emit_imm(st, imm, imm_size(imm));
}
static void
emit_jcc_imm(struct bpf_jit_state *st, uint32_t op, uint32_t dreg,
uint32_t imm, int32_t ofs)
{
if (BPF_OP(op) == BPF_JSET)
emit_tst_imm(st, EBPF_ALU64, dreg, imm);
else
emit_cmp_imm(st, EBPF_ALU64, dreg, imm);
emit_jcc(st, op, ofs);
}
/*
* emit test %<sreg>, %<dreg>
*/
static void
emit_tst_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg)
{
const uint8_t ops = 0x85;
emit_rex(st, op, sreg, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, sreg, dreg);
}
/*
* emit cmp %<sreg>, %<dreg>
*/
static void
emit_cmp_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg)
{
const uint8_t ops = 0x39;
emit_rex(st, op, sreg, dreg);
emit_bytes(st, &ops, sizeof(ops));
emit_modregrm(st, MOD_DIRECT, sreg, dreg);
}
static void
emit_jcc_reg(struct bpf_jit_state *st, uint32_t op, uint32_t sreg,
uint32_t dreg, int32_t ofs)
{
if (BPF_OP(op) == BPF_JSET)
emit_tst_reg(st, EBPF_ALU64, sreg, dreg);
else
emit_cmp_reg(st, EBPF_ALU64, sreg, dreg);
emit_jcc(st, op, ofs);
}
/*
* note that rax:rdx are implicitly used as source/destination registers,
* so some reg spillage is necessary.
* emit:
* mov %rax, %r11
* mov %rdx, %r10
* mov %<dreg>, %rax
* xor %rdx, %rdx
* for divisor as immediate value:
* mov <imm>, %r9
* div %<divisor_reg>
* mov %r10, %rdx
* mov %rax, %<dreg>
* mov %r11, %rax
* either:
* mov %rax, %<dreg>
* OR
* mov %rdx, %<dreg>
* mov %r11, %rax
* mov %r10, %rdx
*/
static void
emit_div(struct bpf_jit_state *st, uint32_t op, uint32_t sreg, uint32_t dreg,
uint32_t imm)
{
uint32_t sr;
const uint8_t ops = 0xF7;
const uint8_t mods = 6;
if (BPF_SRC(op) == BPF_X) {
/* check that src divisor is not zero */
emit_tst_reg(st, BPF_CLASS(op), sreg, sreg);
/* exit with return value zero */
emit_movcc_reg(st, BPF_CLASS(op) | BPF_JEQ | BPF_X, sreg, RAX);
emit_abs_jcc(st, BPF_JMP | BPF_JEQ | BPF_K, st->exit.off);
}