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kernel/arch/mips/net/bpf_jit.c

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/*
* Just-In-Time compiler for BPF filters on MIPS
*
* Copyright (c) 2014 Imagination Technologies Ltd.
* Author: Markos Chandras <markos.chandras@imgtec.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/bitops.h>
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include <linux/moduleloader.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <asm/asm.h>
#include <asm/bitops.h>
#include <asm/cacheflush.h>
#include <asm/cpu-features.h>
#include <asm/uasm.h>
#include "bpf_jit.h"
/* ABI
* r_skb_hl SKB header length
* r_data SKB data pointer
* r_off Offset
* r_A BPF register A
* r_X BPF register X
* r_skb *skb
* r_M *scratch memory
* r_skb_len SKB length
*
* On entry (*bpf_func)(*skb, *filter)
* a0 = MIPS_R_A0 = skb;
* a1 = MIPS_R_A1 = filter;
*
* Stack
* ...
* M[15]
* M[14]
* M[13]
* ...
* M[0] <-- r_M
* saved reg k-1
* saved reg k-2
* ...
* saved reg 0 <-- r_sp
* <no argument area>
*
* Packet layout
*
* <--------------------- len ------------------------>
* <--skb-len(r_skb_hl)-->< ----- skb->data_len ------>
* ----------------------------------------------------
* | skb->data |
* ----------------------------------------------------
*/
#define ptr typeof(unsigned long)
#define SCRATCH_OFF(k) (4 * (k))
/* JIT flags */
#define SEEN_CALL (1 << BPF_MEMWORDS)
#define SEEN_SREG_SFT (BPF_MEMWORDS + 1)
#define SEEN_SREG_BASE (1 << SEEN_SREG_SFT)
#define SEEN_SREG(x) (SEEN_SREG_BASE << (x))
#define SEEN_OFF SEEN_SREG(2)
#define SEEN_A SEEN_SREG(3)
#define SEEN_X SEEN_SREG(4)
#define SEEN_SKB SEEN_SREG(5)
#define SEEN_MEM SEEN_SREG(6)
/* SEEN_SK_DATA also implies skb_hl an skb_len */
#define SEEN_SKB_DATA (SEEN_SREG(7) | SEEN_SREG(1) | SEEN_SREG(0))
/* Arguments used by JIT */
#define ARGS_USED_BY_JIT 2 /* only applicable to 64-bit */
#define SBIT(x) (1 << (x)) /* Signed version of BIT() */
/**
* struct jit_ctx - JIT context
* @skf: The sk_filter
* @prologue_bytes: Number of bytes for prologue
* @idx: Instruction index
* @flags: JIT flags
* @offsets: Instruction offsets
* @target: Memory location for the compiled filter
*/
struct jit_ctx {
const struct bpf_prog *skf;
unsigned int prologue_bytes;
u32 idx;
u32 flags;
u32 *offsets;
u32 *target;
};
static inline int optimize_div(u32 *k)
{
/* power of 2 divides can be implemented with right shift */
if (!(*k & (*k-1))) {
*k = ilog2(*k);
return 1;
}
return 0;
}
static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx);
/* Simply emit the instruction if the JIT memory space has been allocated */
#define emit_instr(ctx, func, ...) \
do { \
if ((ctx)->target != NULL) { \
u32 *p = &(ctx)->target[ctx->idx]; \
uasm_i_##func(&p, ##__VA_ARGS__); \
} \
(ctx)->idx++; \
} while (0)
/*
* Similar to emit_instr but it must be used when we need to emit
* 32-bit or 64-bit instructions
*/
#define emit_long_instr(ctx, func, ...) \
do { \
if ((ctx)->target != NULL) { \
u32 *p = &(ctx)->target[ctx->idx]; \
UASM_i_##func(&p, ##__VA_ARGS__); \
} \
(ctx)->idx++; \
} while (0)
/* Determine if immediate is within the 16-bit signed range */
static inline bool is_range16(s32 imm)
{
return !(imm >= SBIT(15) || imm < -SBIT(15));
}
static inline void emit_addu(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, addu, dst, src1, src2);
}
static inline void emit_nop(struct jit_ctx *ctx)
{
emit_instr(ctx, nop);
}
/* Load a u32 immediate to a register */
static inline void emit_load_imm(unsigned int dst, u32 imm, struct jit_ctx *ctx)
{
if (ctx->target != NULL) {
/* addiu can only handle s16 */
if (!is_range16(imm)) {
u32 *p = &ctx->target[ctx->idx];
uasm_i_lui(&p, r_tmp_imm, (s32)imm >> 16);
p = &ctx->target[ctx->idx + 1];
uasm_i_ori(&p, dst, r_tmp_imm, imm & 0xffff);
} else {
u32 *p = &ctx->target[ctx->idx];
uasm_i_addiu(&p, dst, r_zero, imm);
}
}
ctx->idx++;
if (!is_range16(imm))
ctx->idx++;
}
static inline void emit_or(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, or, dst, src1, src2);
}
static inline void emit_ori(unsigned int dst, unsigned src, u32 imm,
struct jit_ctx *ctx)
{
if (imm >= BIT(16)) {
emit_load_imm(r_tmp, imm, ctx);
emit_or(dst, src, r_tmp, ctx);
} else {
emit_instr(ctx, ori, dst, src, imm);
}
}
static inline void emit_daddiu(unsigned int dst, unsigned int src,
int imm, struct jit_ctx *ctx)
{
/*
* Only used for stack, so the imm is relatively small
* and it fits in 15-bits
*/
emit_instr(ctx, daddiu, dst, src, imm);
}
static inline void emit_addiu(unsigned int dst, unsigned int src,
u32 imm, struct jit_ctx *ctx)
{
if (!is_range16(imm)) {
emit_load_imm(r_tmp, imm, ctx);
emit_addu(dst, r_tmp, src, ctx);
} else {
emit_instr(ctx, addiu, dst, src, imm);
}
}
static inline void emit_and(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, and, dst, src1, src2);
}
static inline void emit_andi(unsigned int dst, unsigned int src,
u32 imm, struct jit_ctx *ctx)
{
/* If imm does not fit in u16 then load it to register */
if (imm >= BIT(16)) {
emit_load_imm(r_tmp, imm, ctx);
emit_and(dst, src, r_tmp, ctx);
} else {
emit_instr(ctx, andi, dst, src, imm);
}
}
static inline void emit_xor(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, xor, dst, src1, src2);
}
static inline void emit_xori(ptr dst, ptr src, u32 imm, struct jit_ctx *ctx)
{
/* If imm does not fit in u16 then load it to register */
if (imm >= BIT(16)) {
emit_load_imm(r_tmp, imm, ctx);
emit_xor(dst, src, r_tmp, ctx);
} else {
emit_instr(ctx, xori, dst, src, imm);
}
}
static inline void emit_stack_offset(int offset, struct jit_ctx *ctx)
{
emit_long_instr(ctx, ADDIU, r_sp, r_sp, offset);
}
static inline void emit_subu(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, subu, dst, src1, src2);
}
static inline void emit_neg(unsigned int reg, struct jit_ctx *ctx)
{
emit_subu(reg, r_zero, reg, ctx);
}
static inline void emit_sllv(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
emit_instr(ctx, sllv, dst, src, sa);
}
static inline void emit_sll(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
/* sa is 5-bits long */
if (sa >= BIT(5))
/* Shifting >= 32 results in zero */
emit_jit_reg_move(dst, r_zero, ctx);
else
emit_instr(ctx, sll, dst, src, sa);
}
static inline void emit_srlv(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
emit_instr(ctx, srlv, dst, src, sa);
}
static inline void emit_srl(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
/* sa is 5-bits long */
if (sa >= BIT(5))
/* Shifting >= 32 results in zero */
emit_jit_reg_move(dst, r_zero, ctx);
else
emit_instr(ctx, srl, dst, src, sa);
}
static inline void emit_slt(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, slt, dst, src1, src2);
}
static inline void emit_sltu(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, sltu, dst, src1, src2);
}
static inline void emit_sltiu(unsigned dst, unsigned int src,
unsigned int imm, struct jit_ctx *ctx)
{
/* 16 bit immediate */
if (!is_range16((s32)imm)) {
emit_load_imm(r_tmp, imm, ctx);
emit_sltu(dst, src, r_tmp, ctx);
} else {
emit_instr(ctx, sltiu, dst, src, imm);
}
}
/* Store register on the stack */
static inline void emit_store_stack_reg(ptr reg, ptr base,
unsigned int offset,
struct jit_ctx *ctx)
{
emit_long_instr(ctx, SW, reg, offset, base);
}
static inline void emit_store(ptr reg, ptr base, unsigned int offset,
struct jit_ctx *ctx)
{
emit_instr(ctx, sw, reg, offset, base);
}
static inline void emit_load_stack_reg(ptr reg, ptr base,
unsigned int offset,
struct jit_ctx *ctx)
{
emit_long_instr(ctx, LW, reg, offset, base);
}
static inline void emit_load(unsigned int reg, unsigned int base,
unsigned int offset, struct jit_ctx *ctx)
{
emit_instr(ctx, lw, reg, offset, base);
}
static inline void emit_load_byte(unsigned int reg, unsigned int base,
unsigned int offset, struct jit_ctx *ctx)
{
emit_instr(ctx, lb, reg, offset, base);
}
static inline void emit_half_load(unsigned int reg, unsigned int base,
unsigned int offset, struct jit_ctx *ctx)
{
emit_instr(ctx, lh, reg, offset, base);
}
static inline void emit_half_load_unsigned(unsigned int reg, unsigned int base,
unsigned int offset, struct jit_ctx *ctx)
{
emit_instr(ctx, lhu, reg, offset, base);
}
static inline void emit_mul(unsigned int dst, unsigned int src1,
unsigned int src2, struct jit_ctx *ctx)
{
emit_instr(ctx, mul, dst, src1, src2);
}
static inline void emit_div(unsigned int dst, unsigned int src,
struct jit_ctx *ctx)
{
if (ctx->target != NULL) {
u32 *p = &ctx->target[ctx->idx];
uasm_i_divu(&p, dst, src);
p = &ctx->target[ctx->idx + 1];
uasm_i_mflo(&p, dst);
}
ctx->idx += 2; /* 2 insts */
}
static inline void emit_mod(unsigned int dst, unsigned int src,
struct jit_ctx *ctx)
{
if (ctx->target != NULL) {
u32 *p = &ctx->target[ctx->idx];
uasm_i_divu(&p, dst, src);
p = &ctx->target[ctx->idx + 1];
uasm_i_mfhi(&p, dst);
}
ctx->idx += 2; /* 2 insts */
}
static inline void emit_dsll(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
emit_instr(ctx, dsll, dst, src, sa);
}
static inline void emit_dsrl32(unsigned int dst, unsigned int src,
unsigned int sa, struct jit_ctx *ctx)
{
emit_instr(ctx, dsrl32, dst, src, sa);
}
static inline void emit_wsbh(unsigned int dst, unsigned int src,
struct jit_ctx *ctx)
{
emit_instr(ctx, wsbh, dst, src);
}
/* load pointer to register */
static inline void emit_load_ptr(unsigned int dst, unsigned int src,
int imm, struct jit_ctx *ctx)
{
/* src contains the base addr of the 32/64-pointer */
emit_long_instr(ctx, LW, dst, imm, src);
}
/* load a function pointer to register */
static inline void emit_load_func(unsigned int reg, ptr imm,
struct jit_ctx *ctx)
{
if (IS_ENABLED(CONFIG_64BIT)) {
/* At this point imm is always 64-bit */
emit_load_imm(r_tmp, (u64)imm >> 32, ctx);
emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */
emit_ori(r_tmp, r_tmp_imm, (imm >> 16) & 0xffff, ctx);
emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */
emit_ori(reg, r_tmp_imm, imm & 0xffff, ctx);
} else {
emit_load_imm(reg, imm, ctx);
}
}
/* Move to real MIPS register */
static inline void emit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx)
{
emit_long_instr(ctx, ADDU, dst, src, r_zero);
}
/* Move to JIT (32-bit) register */
static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx)
{
emit_addu(dst, src, r_zero, ctx);
}
/* Compute the immediate value for PC-relative branches. */
static inline u32 b_imm(unsigned int tgt, struct jit_ctx *ctx)
{
if (ctx->target == NULL)
return 0;
/*
* We want a pc-relative branch. We only do forward branches
* so tgt is always after pc. tgt is the instruction offset
* we want to jump to.
* Branch on MIPS:
* I: target_offset <- sign_extend(offset)
* I+1: PC += target_offset (delay slot)
*
* ctx->idx currently points to the branch instruction
* but the offset is added to the delay slot so we need
* to subtract 4.
*/
return ctx->offsets[tgt] -
(ctx->idx * 4 - ctx->prologue_bytes) - 4;
}
static inline void emit_bcond(int cond, unsigned int reg1, unsigned int reg2,
unsigned int imm, struct jit_ctx *ctx)
{
if (ctx->target != NULL) {
u32 *p = &ctx->target[ctx->idx];
switch (cond) {
case MIPS_COND_EQ:
uasm_i_beq(&p, reg1, reg2, imm);
break;
case MIPS_COND_NE:
uasm_i_bne(&p, reg1, reg2, imm);
break;
case MIPS_COND_ALL:
uasm_i_b(&p, imm);
break;
default:
pr_warn("%s: Unhandled branch conditional: %d\n",
__func__, cond);
}
}
ctx->idx++;
}
static inline void emit_b(unsigned int imm, struct jit_ctx *ctx)
{
emit_bcond(MIPS_COND_ALL, r_zero, r_zero, imm, ctx);
}
static inline void emit_jalr(unsigned int link, unsigned int reg,
struct jit_ctx *ctx)
{
emit_instr(ctx, jalr, link, reg);
}
static inline void emit_jr(unsigned int reg, struct jit_ctx *ctx)
{
emit_instr(ctx, jr, reg);
}
static inline u16 align_sp(unsigned int num)
{
/* Double word alignment for 32-bit, quadword for 64-bit */
unsigned int align = IS_ENABLED(CONFIG_64BIT) ? 16 : 8;
num = (num + (align - 1)) & -align;
return num;
}
static void save_bpf_jit_regs(struct jit_ctx *ctx, unsigned offset)
{
int i = 0, real_off = 0;
u32 sflags, tmp_flags;
/* Adjust the stack pointer */
if (offset)
emit_stack_offset(-align_sp(offset), ctx);
tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT;
/* sflags is essentially a bitmap */
while (tmp_flags) {
if ((sflags >> i) & 0x1) {
emit_store_stack_reg(MIPS_R_S0 + i, r_sp, real_off,
ctx);
real_off += SZREG;
}
i++;
tmp_flags >>= 1;
}
/* save return address */
if (ctx->flags & SEEN_CALL) {
emit_store_stack_reg(r_ra, r_sp, real_off, ctx);
real_off += SZREG;
}
/* Setup r_M leaving the alignment gap if necessary */
if (ctx->flags & SEEN_MEM) {
if (real_off % (SZREG * 2))
real_off += SZREG;
emit_long_instr(ctx, ADDIU, r_M, r_sp, real_off);
}
}
static void restore_bpf_jit_regs(struct jit_ctx *ctx,
unsigned int offset)
{
int i, real_off = 0;
u32 sflags, tmp_flags;
tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT;
/* sflags is a bitmap */
i = 0;
while (tmp_flags) {
if ((sflags >> i) & 0x1) {
emit_load_stack_reg(MIPS_R_S0 + i, r_sp, real_off,
ctx);
real_off += SZREG;
}
i++;
tmp_flags >>= 1;
}
/* restore return address */
if (ctx->flags & SEEN_CALL)
emit_load_stack_reg(r_ra, r_sp, real_off, ctx);
/* Restore the sp and discard the scrach memory */
if (offset)
emit_stack_offset(align_sp(offset), ctx);
}
static unsigned int get_stack_depth(struct jit_ctx *ctx)
{
int sp_off = 0;
/* How may s* regs do we need to preserved? */
sp_off += hweight32(ctx->flags >> SEEN_SREG_SFT) * SZREG;
if (ctx->flags & SEEN_MEM)
sp_off += 4 * BPF_MEMWORDS; /* BPF_MEMWORDS are 32-bit */
if (ctx->flags & SEEN_CALL)
sp_off += SZREG; /* Space for our ra register */
return sp_off;
}
static void build_prologue(struct jit_ctx *ctx)
{
int sp_off;
/* Calculate the total offset for the stack pointer */
sp_off = get_stack_depth(ctx);
save_bpf_jit_regs(ctx, sp_off);
if (ctx->flags & SEEN_SKB)
emit_reg_move(r_skb, MIPS_R_A0, ctx);
if (ctx->flags & SEEN_SKB_DATA) {
/* Load packet length */
emit_load(r_skb_len, r_skb, offsetof(struct sk_buff, len),
ctx);
emit_load(r_tmp, r_skb, offsetof(struct sk_buff, data_len),
ctx);
/* Load the data pointer */
emit_load_ptr(r_skb_data, r_skb,
offsetof(struct sk_buff, data), ctx);
/* Load the header length */
emit_subu(r_skb_hl, r_skb_len, r_tmp, ctx);
}
if (ctx->flags & SEEN_X)
emit_jit_reg_move(r_X, r_zero, ctx);
/*
* Do not leak kernel data to userspace, we only need to clear
* r_A if it is ever used. In fact if it is never used, we
* will not save/restore it, so clearing it in this case would
* corrupt the state of the caller.
*/
if (bpf_needs_clear_a(&ctx->skf->insns[0]) &&
(ctx->flags & SEEN_A))
emit_jit_reg_move(r_A, r_zero, ctx);
}
static void build_epilogue(struct jit_ctx *ctx)
{
unsigned int sp_off;
/* Calculate the total offset for the stack pointer */
sp_off = get_stack_depth(ctx);
restore_bpf_jit_regs(ctx, sp_off);
/* Return */
emit_jr(r_ra, ctx);
emit_nop(ctx);
}
#define CHOOSE_LOAD_FUNC(K, func) \
((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative : func) : \
func##_positive)
static int build_body(struct jit_ctx *ctx)
{
const struct bpf_prog *prog = ctx->skf;
const struct sock_filter *inst;
unsigned int i, off, condt;
u32 k, b_off __maybe_unused;
u8 (*sk_load_func)(unsigned long *skb, int offset);
for (i = 0; i < prog->len; i++) {
u16 code;
inst = &(prog->insns[i]);
pr_debug("%s: code->0x%02x, jt->0x%x, jf->0x%x, k->0x%x\n",
__func__, inst->code, inst->jt, inst->jf, inst->k);
k = inst->k;
code = bpf_anc_helper(inst);
if (ctx->target == NULL)
ctx->offsets[i] = ctx->idx * 4;
switch (code) {
case BPF_LD | BPF_IMM:
/* A <- k ==> li r_A, k */
ctx->flags |= SEEN_A;
emit_load_imm(r_A, k, ctx);
break;
case BPF_LD | BPF_W | BPF_LEN:
BUILD_BUG_ON(sizeof_field(struct sk_buff, len) != 4);
/* A <- len ==> lw r_A, offset(skb) */
ctx->flags |= SEEN_SKB | SEEN_A;
off = offsetof(struct sk_buff, len);
emit_load(r_A, r_skb, off, ctx);
break;
case BPF_LD | BPF_MEM:
/* A <- M[k] ==> lw r_A, offset(M) */
ctx->flags |= SEEN_MEM | SEEN_A;
emit_load(r_A, r_M, SCRATCH_OFF(k), ctx);
break;
case BPF_LD | BPF_W | BPF_ABS:
/* A <- P[k:4] */
sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_word);
goto load;
case BPF_LD | BPF_H | BPF_ABS:
/* A <- P[k:2] */
sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_half);
goto load;
case BPF_LD | BPF_B | BPF_ABS:
/* A <- P[k:1] */
sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_byte);
load:
emit_load_imm(r_off, k, ctx);
load_common:
ctx->flags |= SEEN_CALL | SEEN_OFF |
SEEN_SKB | SEEN_A | SEEN_SKB_DATA;
emit_load_func(r_s0, (ptr)sk_load_func, ctx);
emit_reg_move(MIPS_R_A0, r_skb, ctx);
emit_jalr(MIPS_R_RA, r_s0, ctx);
/* Load second argument to delay slot */
emit_reg_move(MIPS_R_A1, r_off, ctx);
/* Check the error value */
emit_bcond(MIPS_COND_EQ, r_ret, 0, b_imm(i + 1, ctx),
ctx);
/* Load return register on DS for failures */
emit_reg_move(r_ret, r_zero, ctx);
/* Return with error */
emit_b(b_imm(prog->len, ctx), ctx);
emit_nop(ctx);
break;
case BPF_LD | BPF_W | BPF_IND:
/* A <- P[X + k:4] */
sk_load_func = sk_load_word;
goto load_ind;
case BPF_LD | BPF_H | BPF_IND:
/* A <- P[X + k:2] */
sk_load_func = sk_load_half;
goto load_ind;
case BPF_LD | BPF_B | BPF_IND:
/* A <- P[X + k:1] */
sk_load_func = sk_load_byte;
load_ind:
ctx->flags |= SEEN_OFF | SEEN_X;
emit_addiu(r_off, r_X, k, ctx);
goto load_common;
case BPF_LDX | BPF_IMM:
/* X <- k */
ctx->flags |= SEEN_X;
emit_load_imm(r_X, k, ctx);
break;
case BPF_LDX | BPF_MEM:
/* X <- M[k] */
ctx->flags |= SEEN_X | SEEN_MEM;
emit_load(r_X, r_M, SCRATCH_OFF(k), ctx);
break;
case BPF_LDX | BPF_W | BPF_LEN:
/* X <- len */
ctx->flags |= SEEN_X | SEEN_SKB;
off = offsetof(struct sk_buff, len);
emit_load(r_X, r_skb, off, ctx);
break;
case BPF_LDX | BPF_B | BPF_MSH:
/* X <- 4 * (P[k:1] & 0xf) */
ctx->flags |= SEEN_X | SEEN_CALL | SEEN_SKB;
/* Load offset to a1 */
emit_load_func(r_s0, (ptr)sk_load_byte, ctx);
/*
* This may emit two instructions so it may not fit
* in the delay slot. So use a0 in the delay slot.
*/
emit_load_imm(MIPS_R_A1, k, ctx);
emit_jalr(MIPS_R_RA, r_s0, ctx);
emit_reg_move(MIPS_R_A0, r_skb, ctx); /* delay slot */
/* Check the error value */
emit_bcond(MIPS_COND_NE, r_ret, 0,
b_imm(prog->len, ctx), ctx);
emit_reg_move(r_ret, r_zero, ctx);
/* We are good */
/* X <- P[1:K] & 0xf */
emit_andi(r_X, r_A, 0xf, ctx);
/* X << 2 */
emit_b(b_imm(i + 1, ctx), ctx);
emit_sll(r_X, r_X, 2, ctx); /* delay slot */
break;
case BPF_ST:
/* M[k] <- A */
ctx->flags |= SEEN_MEM | SEEN_A;
emit_store(r_A, r_M, SCRATCH_OFF(k), ctx);
break;
case BPF_STX:
/* M[k] <- X */
ctx->flags |= SEEN_MEM | SEEN_X;
emit_store(r_X, r_M, SCRATCH_OFF(k), ctx);
break;
case BPF_ALU | BPF_ADD | BPF_K:
/* A += K */
ctx->flags |= SEEN_A;
emit_addiu(r_A, r_A, k, ctx);
break;
case BPF_ALU | BPF_ADD | BPF_X:
/* A += X */
ctx->flags |= SEEN_A | SEEN_X;
emit_addu(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_SUB | BPF_K:
/* A -= K */
ctx->flags |= SEEN_A;
emit_addiu(r_A, r_A, -k, ctx);
break;
case BPF_ALU | BPF_SUB | BPF_X:
/* A -= X */
ctx->flags |= SEEN_A | SEEN_X;
emit_subu(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_MUL | BPF_K:
/* A *= K */
/* Load K to scratch register before MUL */
ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
emit_mul(r_A, r_A, r_s0, ctx);
break;
case BPF_ALU | BPF_MUL | BPF_X:
/* A *= X */
ctx->flags |= SEEN_A | SEEN_X;
emit_mul(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_DIV | BPF_K:
/* A /= k */
if (k == 1)
break;
if (optimize_div(&k)) {
ctx->flags |= SEEN_A;
emit_srl(r_A, r_A, k, ctx);
break;
}
ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
emit_div(r_A, r_s0, ctx);
break;
case BPF_ALU | BPF_MOD | BPF_K:
/* A %= k */
if (k == 1) {
ctx->flags |= SEEN_A;
emit_jit_reg_move(r_A, r_zero, ctx);
} else {
ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
emit_mod(r_A, r_s0, ctx);
}
break;
case BPF_ALU | BPF_DIV | BPF_X:
/* A /= X */
ctx->flags |= SEEN_X | SEEN_A;
/* Check if r_X is zero */
emit_bcond(MIPS_COND_EQ, r_X, r_zero,
b_imm(prog->len, ctx), ctx);
emit_load_imm(r_ret, 0, ctx); /* delay slot */
emit_div(r_A, r_X, ctx);
break;
case BPF_ALU | BPF_MOD | BPF_X:
/* A %= X */
ctx->flags |= SEEN_X | SEEN_A;
/* Check if r_X is zero */
emit_bcond(MIPS_COND_EQ, r_X, r_zero,
b_imm(prog->len, ctx), ctx);
emit_load_imm(r_ret, 0, ctx); /* delay slot */
emit_mod(r_A, r_X, ctx);
break;
case BPF_ALU | BPF_OR | BPF_K:
/* A |= K */
ctx->flags |= SEEN_A;
emit_ori(r_A, r_A, k, ctx);
break;
case BPF_ALU | BPF_OR | BPF_X:
/* A |= X */
ctx->flags |= SEEN_A;
emit_ori(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_XOR | BPF_K:
/* A ^= k */
ctx->flags |= SEEN_A;
emit_xori(r_A, r_A, k, ctx);
break;
case BPF_ANC | SKF_AD_ALU_XOR_X:
case BPF_ALU | BPF_XOR | BPF_X:
/* A ^= X */
ctx->flags |= SEEN_A;
emit_xor(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_AND | BPF_K:
/* A &= K */
ctx->flags |= SEEN_A;
emit_andi(r_A, r_A, k, ctx);
break;
case BPF_ALU | BPF_AND | BPF_X:
/* A &= X */
ctx->flags |= SEEN_A | SEEN_X;
emit_and(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_LSH | BPF_K:
/* A <<= K */
ctx->flags |= SEEN_A;
emit_sll(r_A, r_A, k, ctx);
break;
case BPF_ALU | BPF_LSH | BPF_X:
/* A <<= X */
ctx->flags |= SEEN_A | SEEN_X;
emit_sllv(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_RSH | BPF_K:
/* A >>= K */
ctx->flags |= SEEN_A;
emit_srl(r_A, r_A, k, ctx);
break;
case BPF_ALU | BPF_RSH | BPF_X:
ctx->flags |= SEEN_A | SEEN_X;
emit_srlv(r_A, r_A, r_X, ctx);
break;
case BPF_ALU | BPF_NEG:
/* A = -A */
ctx->flags |= SEEN_A;
emit_neg(r_A, ctx);
break;
case BPF_JMP | BPF_JA:
/* pc += K */
emit_b(b_imm(i + k + 1, ctx), ctx);
emit_nop(ctx);
break;
case BPF_JMP | BPF_JEQ | BPF_K:
/* pc += ( A == K ) ? pc->jt : pc->jf */
condt = MIPS_COND_EQ | MIPS_COND_K;
goto jmp_cmp;
case BPF_JMP | BPF_JEQ | BPF_X:
ctx->flags |= SEEN_X;
/* pc += ( A == X ) ? pc->jt : pc->jf */
condt = MIPS_COND_EQ | MIPS_COND_X;
goto jmp_cmp;
case BPF_JMP | BPF_JGE | BPF_K:
/* pc += ( A >= K ) ? pc->jt : pc->jf */
condt = MIPS_COND_GE | MIPS_COND_K;
goto jmp_cmp;
case BPF_JMP | BPF_JGE | BPF_X:
ctx->flags |= SEEN_X;
/* pc += ( A >= X ) ? pc->jt : pc->jf */
condt = MIPS_COND_GE | MIPS_COND_X;
goto jmp_cmp;
case BPF_JMP | BPF_JGT | BPF_K:
/* pc += ( A > K ) ? pc->jt : pc->jf */
condt = MIPS_COND_GT | MIPS_COND_K;
goto jmp_cmp;
case BPF_JMP | BPF_JGT | BPF_X:
ctx->flags |= SEEN_X;
/* pc += ( A > X ) ? pc->jt : pc->jf */
condt = MIPS_COND_GT | MIPS_COND_X;
jmp_cmp:
/* Greater or Equal */
if ((condt & MIPS_COND_GE) ||
(condt & MIPS_COND_GT)) {
if (condt & MIPS_COND_K) { /* K */
ctx->flags |= SEEN_A;
emit_sltiu(r_s0, r_A, k, ctx);
} else { /* X */
ctx->flags |= SEEN_A |
SEEN_X;
emit_sltu(r_s0, r_A, r_X, ctx);
}
/* A < (K|X) ? r_scrach = 1 */
b_off = b_imm(i + inst->jf + 1, ctx);
emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off,
ctx);
emit_nop(ctx);
/* A > (K|X) ? scratch = 0 */
if (condt & MIPS_COND_GT) {
/* Checking for equality */
ctx->flags |= SEEN_A | SEEN_X;
if (condt & MIPS_COND_K)
emit_load_imm(r_s0, k, ctx);
else
emit_jit_reg_move(r_s0, r_X,
ctx);
b_off = b_imm(i + inst->jf + 1, ctx);
emit_bcond(MIPS_COND_EQ, r_A, r_s0,
b_off, ctx);
emit_nop(ctx);
/* Finally, A > K|X */
b_off = b_imm(i + inst->jt + 1, ctx);
emit_b(b_off, ctx);
emit_nop(ctx);
} else {
/* A >= (K|X) so jump */
b_off = b_imm(i + inst->jt + 1, ctx);
emit_b(b_off, ctx);
emit_nop(ctx);
}
} else {
/* A == K|X */
if (condt & MIPS_COND_K) { /* K */
ctx->flags |= SEEN_A;
emit_load_imm(r_s0, k, ctx);
/* jump true */
b_off = b_imm(i + inst->jt + 1, ctx);
emit_bcond(MIPS_COND_EQ, r_A, r_s0,
b_off, ctx);
emit_nop(ctx);
/* jump false */
b_off = b_imm(i + inst->jf + 1,
ctx);
emit_bcond(MIPS_COND_NE, r_A, r_s0,
b_off, ctx);
emit_nop(ctx);
} else { /* X */
/* jump true */
ctx->flags |= SEEN_A | SEEN_X;
b_off = b_imm(i + inst->jt + 1,
ctx);
emit_bcond(MIPS_COND_EQ, r_A, r_X,
b_off, ctx);
emit_nop(ctx);
/* jump false */
b_off = b_imm(i + inst->jf + 1, ctx);
emit_bcond(MIPS_COND_NE, r_A, r_X,
b_off, ctx);
emit_nop(ctx);
}
}
break;
case BPF_JMP | BPF_JSET | BPF_K:
ctx->flags |= SEEN_A;
/* pc += (A & K) ? pc -> jt : pc -> jf */
emit_load_imm(r_s1, k, ctx);
emit_and(r_s0, r_A, r_s1, ctx);
/* jump true */
b_off = b_imm(i + inst->jt + 1, ctx);
emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx);
emit_nop(ctx);
/* jump false */
b_off = b_imm(i + inst->jf + 1, ctx);
emit_b(b_off, ctx);
emit_nop(ctx);
break;
case BPF_JMP | BPF_JSET | BPF_X:
ctx->flags |= SEEN_X | SEEN_A;
/* pc += (A & X) ? pc -> jt : pc -> jf */
emit_and(r_s0, r_A, r_X, ctx);
/* jump true */
b_off = b_imm(i + inst->jt + 1, ctx);
emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx);
emit_nop(ctx);
/* jump false */
b_off = b_imm(i + inst->jf + 1, ctx);
emit_b(b_off, ctx);
emit_nop(ctx);
break;
case BPF_RET | BPF_A:
ctx->flags |= SEEN_A;
if (i != prog->len - 1)
/*
* If this is not the last instruction
* then jump to the epilogue
*/
emit_b(b_imm(prog->len, ctx), ctx);
emit_reg_move(r_ret, r_A, ctx); /* delay slot */
break;
case BPF_RET | BPF_K:
/*
* It can emit two instructions so it does not fit on
* the delay slot.
*/
emit_load_imm(r_ret, k, ctx);
if (i != prog->len - 1) {
/*
* If this is not the last instruction
* then jump to the epilogue
*/
emit_b(b_imm(prog->len, ctx), ctx);
emit_nop(ctx);
}
break;
case BPF_MISC | BPF_TAX:
/* X = A */
ctx->flags |= SEEN_X | SEEN_A;
emit_jit_reg_move(r_X, r_A, ctx);
break;
case BPF_MISC | BPF_TXA:
/* A = X */
ctx->flags |= SEEN_A | SEEN_X;
emit_jit_reg_move(r_A, r_X, ctx);
break;
/* AUX */
case BPF_ANC | SKF_AD_PROTOCOL:
/* A = ntohs(skb->protocol */
ctx->flags |= SEEN_SKB | SEEN_OFF | SEEN_A;
BUILD_BUG_ON(sizeof_field(struct sk_buff,
protocol) != 2);
off = offsetof(struct sk_buff, protocol);
emit_half_load(r_A, r_skb, off, ctx);
#ifdef CONFIG_CPU_LITTLE_ENDIAN
/* This needs little endian fixup */
if (cpu_has_wsbh) {
/* R2 and later have the wsbh instruction */
emit_wsbh(r_A, r_A, ctx);
} else {
/* Get first byte */
emit_andi(r_tmp_imm, r_A, 0xff, ctx);
/* Shift it */
emit_sll(r_tmp, r_tmp_imm, 8, ctx);
/* Get second byte */
emit_srl(r_tmp_imm, r_A, 8, ctx);
emit_andi(r_tmp_imm, r_tmp_imm, 0xff, ctx);
/* Put everyting together in r_A */
emit_or(r_A, r_tmp, r_tmp_imm, ctx);
}
#endif
break;
case BPF_ANC | SKF_AD_CPU:
ctx->flags |= SEEN_A | SEEN_OFF;
/* A = current_thread_info()->cpu */
BUILD_BUG_ON(sizeof_field(struct thread_info,
cpu) != 4);
off = offsetof(struct thread_info, cpu);
/* $28/gp points to the thread_info struct */
emit_load(r_A, 28, off, ctx);
break;
case BPF_ANC | SKF_AD_IFINDEX:
/* A = skb->dev->ifindex */
case BPF_ANC | SKF_AD_HATYPE:
/* A = skb->dev->type */
ctx->flags |= SEEN_SKB | SEEN_A;
off = offsetof(struct sk_buff, dev);
/* Load *dev pointer */
emit_load_ptr(r_s0, r_skb, off, ctx);
/* error (0) in the delay slot */
emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
b_imm(prog->len, ctx), ctx);
emit_reg_move(r_ret, r_zero, ctx);
if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
BUILD_BUG_ON(sizeof_field(struct net_device, ifindex) != 4);
off = offsetof(struct net_device, ifindex);
emit_load(r_A, r_s0, off, ctx);
} else { /* (code == (BPF_ANC | SKF_AD_HATYPE) */
BUILD_BUG_ON(sizeof_field(struct net_device, type) != 2);
off = offsetof(struct net_device, type);
emit_half_load_unsigned(r_A, r_s0, off, ctx);
}
break;
case BPF_ANC | SKF_AD_MARK:
ctx->flags |= SEEN_SKB | SEEN_A;
BUILD_BUG_ON(sizeof_field(struct sk_buff, mark) != 4);
off = offsetof(struct sk_buff, mark);
emit_load(r_A, r_skb, off, ctx);
break;
case BPF_ANC | SKF_AD_RXHASH:
ctx->flags |= SEEN_SKB | SEEN_A;
BUILD_BUG_ON(sizeof_field(struct sk_buff, hash) != 4);
off = offsetof(struct sk_buff, hash);
emit_load(r_A, r_skb, off, ctx);
break;
case BPF_ANC | SKF_AD_VLAN_TAG:
ctx->flags |= SEEN_SKB | SEEN_A;
BUILD_BUG_ON(sizeof_field(struct sk_buff,
vlan_tci) != 2);
off = offsetof(struct sk_buff, vlan_tci);
emit_half_load_unsigned(r_A, r_skb, off, ctx);
break;
case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
ctx->flags |= SEEN_SKB | SEEN_A;
emit_load_byte(r_A, r_skb, PKT_VLAN_PRESENT_OFFSET(), ctx);
if (PKT_VLAN_PRESENT_BIT)
emit_srl(r_A, r_A, PKT_VLAN_PRESENT_BIT, ctx);
if (PKT_VLAN_PRESENT_BIT < 7)
emit_andi(r_A, r_A, 1, ctx);
break;
case BPF_ANC | SKF_AD_PKTTYPE:
ctx->flags |= SEEN_SKB;
emit_load_byte(r_tmp, r_skb, PKT_TYPE_OFFSET(), ctx);
/* Keep only the last 3 bits */
emit_andi(r_A, r_tmp, PKT_TYPE_MAX, ctx);
#ifdef __BIG_ENDIAN_BITFIELD
/* Get the actual packet type to the lower 3 bits */
emit_srl(r_A, r_A, 5, ctx);
#endif
break;
case BPF_ANC | SKF_AD_QUEUE:
ctx->flags |= SEEN_SKB | SEEN_A;
BUILD_BUG_ON(sizeof_field(struct sk_buff,
queue_mapping) != 2);
BUILD_BUG_ON(offsetof(struct sk_buff,
queue_mapping) > 0xff);
off = offsetof(struct sk_buff, queue_mapping);
emit_half_load_unsigned(r_A, r_skb, off, ctx);
break;
default:
pr_debug("%s: Unhandled opcode: 0x%02x\n", __FILE__,
inst->code);
return -1;
}
}
/* compute offsets only during the first pass */
if (ctx->target == NULL)
ctx->offsets[i] = ctx->idx * 4;
return 0;
}
void bpf_jit_compile(struct bpf_prog *fp)
{
struct jit_ctx ctx;
unsigned int alloc_size, tmp_idx;
if (!bpf_jit_enable)
return;
memset(&ctx, 0, sizeof(ctx));
ctx.offsets = kcalloc(fp->len + 1, sizeof(*ctx.offsets), GFP_KERNEL);
if (ctx.offsets == NULL)
return;
ctx.skf = fp;
if (build_body(&ctx))
goto out;
tmp_idx = ctx.idx;
build_prologue(&ctx);
ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4;
/* just to complete the ctx.idx count */
build_epilogue(&ctx);
alloc_size = 4 * ctx.idx;
ctx.target = module_alloc(alloc_size);
if (ctx.target == NULL)
goto out;
/* Clean it */
memset(ctx.target, 0, alloc_size);
ctx.idx = 0;
/* Generate the actual JIT code */
build_prologue(&ctx);
build_body(&ctx);
build_epilogue(&ctx);
/* Update the icache */
flush_icache_range((ptr)ctx.target, (ptr)(ctx.target + ctx.idx));
if (bpf_jit_enable > 1)
/* Dump JIT code */
bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
fp->bpf_func = (void *)ctx.target;
fp->jited = 1;
out:
kfree(ctx.offsets);
}
void bpf_jit_free(struct bpf_prog *fp)
{
if (fp->jited)
module_memfree(fp->bpf_func);
bpf_prog_unlock_free(fp);
}
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