2 * Just-In-Time compiler for BPF filters on MIPS
4 * Copyright (c) 2014 Imagination Technologies Ltd.
5 * Author: Markos Chandras <markos.chandras@imgtec.com>
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; version 2 of the License.
12 #include <linux/bitops.h>
13 #include <linux/compiler.h>
14 #include <linux/errno.h>
15 #include <linux/filter.h>
16 #include <linux/if_vlan.h>
17 #include <linux/moduleloader.h>
18 #include <linux/netdevice.h>
19 #include <linux/string.h>
20 #include <linux/slab.h>
21 #include <linux/types.h>
23 #include <asm/bitops.h>
24 #include <asm/cacheflush.h>
25 #include <asm/cpu-features.h>
31 * r_skb_hl SKB header length
32 * r_data SKB data pointer
38 * r_skb_len SKB length
40 * On entry (*bpf_func)(*skb, *filter)
41 * a0 = MIPS_R_A0 = skb;
42 * a1 = MIPS_R_A1 = filter;
54 * saved reg 0 <-- r_sp
59 * <--------------------- len ------------------------>
60 * <--skb-len(r_skb_hl)-->< ----- skb->data_len ------>
61 * ----------------------------------------------------
63 * ----------------------------------------------------
66 #define ptr typeof(unsigned long)
68 #define SCRATCH_OFF(k) (4 * (k))
71 #define SEEN_CALL (1 << BPF_MEMWORDS)
72 #define SEEN_SREG_SFT (BPF_MEMWORDS + 1)
73 #define SEEN_SREG_BASE (1 << SEEN_SREG_SFT)
74 #define SEEN_SREG(x) (SEEN_SREG_BASE << (x))
75 #define SEEN_OFF SEEN_SREG(2)
76 #define SEEN_A SEEN_SREG(3)
77 #define SEEN_X SEEN_SREG(4)
78 #define SEEN_SKB SEEN_SREG(5)
79 #define SEEN_MEM SEEN_SREG(6)
80 /* SEEN_SK_DATA also implies skb_hl an skb_len */
81 #define SEEN_SKB_DATA (SEEN_SREG(7) | SEEN_SREG(1) | SEEN_SREG(0))
83 /* Arguments used by JIT */
84 #define ARGS_USED_BY_JIT 2 /* only applicable to 64-bit */
86 #define SBIT(x) (1 << (x)) /* Signed version of BIT() */
89 * struct jit_ctx - JIT context
91 * @prologue_bytes: Number of bytes for prologue
92 * @idx: Instruction index
94 * @offsets: Instruction offsets
95 * @target: Memory location for the compiled filter
98 const struct bpf_prog
*skf
;
99 unsigned int prologue_bytes
;
107 static inline int optimize_div(u32
*k
)
109 /* power of 2 divides can be implemented with right shift */
110 if (!(*k
& (*k
-1))) {
118 static inline void emit_jit_reg_move(ptr dst
, ptr src
, struct jit_ctx
*ctx
);
120 /* Simply emit the instruction if the JIT memory space has been allocated */
121 #define emit_instr(ctx, func, ...) \
123 if ((ctx)->target != NULL) { \
124 u32 *p = &(ctx)->target[ctx->idx]; \
125 uasm_i_##func(&p, ##__VA_ARGS__); \
131 * Similar to emit_instr but it must be used when we need to emit
132 * 32-bit or 64-bit instructions
134 #define emit_long_instr(ctx, func, ...) \
136 if ((ctx)->target != NULL) { \
137 u32 *p = &(ctx)->target[ctx->idx]; \
138 UASM_i_##func(&p, ##__VA_ARGS__); \
143 /* Determine if immediate is within the 16-bit signed range */
144 static inline bool is_range16(s32 imm
)
146 return !(imm
>= SBIT(15) || imm
< -SBIT(15));
149 static inline void emit_addu(unsigned int dst
, unsigned int src1
,
150 unsigned int src2
, struct jit_ctx
*ctx
)
152 emit_instr(ctx
, addu
, dst
, src1
, src2
);
155 static inline void emit_nop(struct jit_ctx
*ctx
)
157 emit_instr(ctx
, nop
);
160 /* Load a u32 immediate to a register */
161 static inline void emit_load_imm(unsigned int dst
, u32 imm
, struct jit_ctx
*ctx
)
163 if (ctx
->target
!= NULL
) {
164 /* addiu can only handle s16 */
165 if (!is_range16(imm
)) {
166 u32
*p
= &ctx
->target
[ctx
->idx
];
167 uasm_i_lui(&p
, r_tmp_imm
, (s32
)imm
>> 16);
168 p
= &ctx
->target
[ctx
->idx
+ 1];
169 uasm_i_ori(&p
, dst
, r_tmp_imm
, imm
& 0xffff);
171 u32
*p
= &ctx
->target
[ctx
->idx
];
172 uasm_i_addiu(&p
, dst
, r_zero
, imm
);
177 if (!is_range16(imm
))
181 static inline void emit_or(unsigned int dst
, unsigned int src1
,
182 unsigned int src2
, struct jit_ctx
*ctx
)
184 emit_instr(ctx
, or, dst
, src1
, src2
);
187 static inline void emit_ori(unsigned int dst
, unsigned src
, u32 imm
,
190 if (imm
>= BIT(16)) {
191 emit_load_imm(r_tmp
, imm
, ctx
);
192 emit_or(dst
, src
, r_tmp
, ctx
);
194 emit_instr(ctx
, ori
, dst
, src
, imm
);
198 static inline void emit_daddiu(unsigned int dst
, unsigned int src
,
199 int imm
, struct jit_ctx
*ctx
)
202 * Only used for stack, so the imm is relatively small
203 * and it fits in 15-bits
205 emit_instr(ctx
, daddiu
, dst
, src
, imm
);
208 static inline void emit_addiu(unsigned int dst
, unsigned int src
,
209 u32 imm
, struct jit_ctx
*ctx
)
211 if (!is_range16(imm
)) {
212 emit_load_imm(r_tmp
, imm
, ctx
);
213 emit_addu(dst
, r_tmp
, src
, ctx
);
215 emit_instr(ctx
, addiu
, dst
, src
, imm
);
219 static inline void emit_and(unsigned int dst
, unsigned int src1
,
220 unsigned int src2
, struct jit_ctx
*ctx
)
222 emit_instr(ctx
, and, dst
, src1
, src2
);
225 static inline void emit_andi(unsigned int dst
, unsigned int src
,
226 u32 imm
, struct jit_ctx
*ctx
)
228 /* If imm does not fit in u16 then load it to register */
229 if (imm
>= BIT(16)) {
230 emit_load_imm(r_tmp
, imm
, ctx
);
231 emit_and(dst
, src
, r_tmp
, ctx
);
233 emit_instr(ctx
, andi
, dst
, src
, imm
);
237 static inline void emit_xor(unsigned int dst
, unsigned int src1
,
238 unsigned int src2
, struct jit_ctx
*ctx
)
240 emit_instr(ctx
, xor, dst
, src1
, src2
);
243 static inline void emit_xori(ptr dst
, ptr src
, u32 imm
, struct jit_ctx
*ctx
)
245 /* If imm does not fit in u16 then load it to register */
246 if (imm
>= BIT(16)) {
247 emit_load_imm(r_tmp
, imm
, ctx
);
248 emit_xor(dst
, src
, r_tmp
, ctx
);
250 emit_instr(ctx
, xori
, dst
, src
, imm
);
254 static inline void emit_stack_offset(int offset
, struct jit_ctx
*ctx
)
256 emit_long_instr(ctx
, ADDIU
, r_sp
, r_sp
, offset
);
259 static inline void emit_subu(unsigned int dst
, unsigned int src1
,
260 unsigned int src2
, struct jit_ctx
*ctx
)
262 emit_instr(ctx
, subu
, dst
, src1
, src2
);
265 static inline void emit_neg(unsigned int reg
, struct jit_ctx
*ctx
)
267 emit_subu(reg
, r_zero
, reg
, ctx
);
270 static inline void emit_sllv(unsigned int dst
, unsigned int src
,
271 unsigned int sa
, struct jit_ctx
*ctx
)
273 emit_instr(ctx
, sllv
, dst
, src
, sa
);
276 static inline void emit_sll(unsigned int dst
, unsigned int src
,
277 unsigned int sa
, struct jit_ctx
*ctx
)
279 /* sa is 5-bits long */
281 /* Shifting >= 32 results in zero */
282 emit_jit_reg_move(dst
, r_zero
, ctx
);
284 emit_instr(ctx
, sll
, dst
, src
, sa
);
287 static inline void emit_srlv(unsigned int dst
, unsigned int src
,
288 unsigned int sa
, struct jit_ctx
*ctx
)
290 emit_instr(ctx
, srlv
, dst
, src
, sa
);
293 static inline void emit_srl(unsigned int dst
, unsigned int src
,
294 unsigned int sa
, struct jit_ctx
*ctx
)
296 /* sa is 5-bits long */
298 /* Shifting >= 32 results in zero */
299 emit_jit_reg_move(dst
, r_zero
, ctx
);
301 emit_instr(ctx
, srl
, dst
, src
, sa
);
304 static inline void emit_slt(unsigned int dst
, unsigned int src1
,
305 unsigned int src2
, struct jit_ctx
*ctx
)
307 emit_instr(ctx
, slt
, dst
, src1
, src2
);
310 static inline void emit_sltu(unsigned int dst
, unsigned int src1
,
311 unsigned int src2
, struct jit_ctx
*ctx
)
313 emit_instr(ctx
, sltu
, dst
, src1
, src2
);
316 static inline void emit_sltiu(unsigned dst
, unsigned int src
,
317 unsigned int imm
, struct jit_ctx
*ctx
)
319 /* 16 bit immediate */
320 if (!is_range16((s32
)imm
)) {
321 emit_load_imm(r_tmp
, imm
, ctx
);
322 emit_sltu(dst
, src
, r_tmp
, ctx
);
324 emit_instr(ctx
, sltiu
, dst
, src
, imm
);
329 /* Store register on the stack */
330 static inline void emit_store_stack_reg(ptr reg
, ptr base
,
334 emit_long_instr(ctx
, SW
, reg
, offset
, base
);
337 static inline void emit_store(ptr reg
, ptr base
, unsigned int offset
,
340 emit_instr(ctx
, sw
, reg
, offset
, base
);
343 static inline void emit_load_stack_reg(ptr reg
, ptr base
,
347 emit_long_instr(ctx
, LW
, reg
, offset
, base
);
350 static inline void emit_load(unsigned int reg
, unsigned int base
,
351 unsigned int offset
, struct jit_ctx
*ctx
)
353 emit_instr(ctx
, lw
, reg
, offset
, base
);
356 static inline void emit_load_byte(unsigned int reg
, unsigned int base
,
357 unsigned int offset
, struct jit_ctx
*ctx
)
359 emit_instr(ctx
, lb
, reg
, offset
, base
);
362 static inline void emit_half_load(unsigned int reg
, unsigned int base
,
363 unsigned int offset
, struct jit_ctx
*ctx
)
365 emit_instr(ctx
, lh
, reg
, offset
, base
);
368 static inline void emit_mul(unsigned int dst
, unsigned int src1
,
369 unsigned int src2
, struct jit_ctx
*ctx
)
371 emit_instr(ctx
, mul
, dst
, src1
, src2
);
374 static inline void emit_div(unsigned int dst
, unsigned int src
,
377 if (ctx
->target
!= NULL
) {
378 u32
*p
= &ctx
->target
[ctx
->idx
];
379 uasm_i_divu(&p
, dst
, src
);
380 p
= &ctx
->target
[ctx
->idx
+ 1];
381 uasm_i_mflo(&p
, dst
);
383 ctx
->idx
+= 2; /* 2 insts */
386 static inline void emit_mod(unsigned int dst
, unsigned int src
,
389 if (ctx
->target
!= NULL
) {
390 u32
*p
= &ctx
->target
[ctx
->idx
];
391 uasm_i_divu(&p
, dst
, src
);
392 p
= &ctx
->target
[ctx
->idx
+ 1];
393 uasm_i_mfhi(&p
, dst
);
395 ctx
->idx
+= 2; /* 2 insts */
398 static inline void emit_dsll(unsigned int dst
, unsigned int src
,
399 unsigned int sa
, struct jit_ctx
*ctx
)
401 emit_instr(ctx
, dsll
, dst
, src
, sa
);
404 static inline void emit_dsrl32(unsigned int dst
, unsigned int src
,
405 unsigned int sa
, struct jit_ctx
*ctx
)
407 emit_instr(ctx
, dsrl32
, dst
, src
, sa
);
410 static inline void emit_wsbh(unsigned int dst
, unsigned int src
,
413 emit_instr(ctx
, wsbh
, dst
, src
);
416 /* load pointer to register */
417 static inline void emit_load_ptr(unsigned int dst
, unsigned int src
,
418 int imm
, struct jit_ctx
*ctx
)
420 /* src contains the base addr of the 32/64-pointer */
421 emit_long_instr(ctx
, LW
, dst
, imm
, src
);
424 /* load a function pointer to register */
425 static inline void emit_load_func(unsigned int reg
, ptr imm
,
428 if (IS_ENABLED(CONFIG_64BIT
)) {
429 /* At this point imm is always 64-bit */
430 emit_load_imm(r_tmp
, (u64
)imm
>> 32, ctx
);
431 emit_dsll(r_tmp_imm
, r_tmp
, 16, ctx
); /* left shift by 16 */
432 emit_ori(r_tmp
, r_tmp_imm
, (imm
>> 16) & 0xffff, ctx
);
433 emit_dsll(r_tmp_imm
, r_tmp
, 16, ctx
); /* left shift by 16 */
434 emit_ori(reg
, r_tmp_imm
, imm
& 0xffff, ctx
);
436 emit_load_imm(reg
, imm
, ctx
);
440 /* Move to real MIPS register */
441 static inline void emit_reg_move(ptr dst
, ptr src
, struct jit_ctx
*ctx
)
443 emit_long_instr(ctx
, ADDU
, dst
, src
, r_zero
);
446 /* Move to JIT (32-bit) register */
447 static inline void emit_jit_reg_move(ptr dst
, ptr src
, struct jit_ctx
*ctx
)
449 emit_addu(dst
, src
, r_zero
, ctx
);
452 /* Compute the immediate value for PC-relative branches. */
453 static inline u32
b_imm(unsigned int tgt
, struct jit_ctx
*ctx
)
455 if (ctx
->target
== NULL
)
459 * We want a pc-relative branch. We only do forward branches
460 * so tgt is always after pc. tgt is the instruction offset
461 * we want to jump to.
464 * I: target_offset <- sign_extend(offset)
465 * I+1: PC += target_offset (delay slot)
467 * ctx->idx currently points to the branch instruction
468 * but the offset is added to the delay slot so we need
471 return ctx
->offsets
[tgt
] -
472 (ctx
->idx
* 4 - ctx
->prologue_bytes
) - 4;
475 static inline void emit_bcond(int cond
, unsigned int reg1
, unsigned int reg2
,
476 unsigned int imm
, struct jit_ctx
*ctx
)
478 if (ctx
->target
!= NULL
) {
479 u32
*p
= &ctx
->target
[ctx
->idx
];
483 uasm_i_beq(&p
, reg1
, reg2
, imm
);
486 uasm_i_bne(&p
, reg1
, reg2
, imm
);
492 pr_warn("%s: Unhandled branch conditional: %d\n",
499 static inline void emit_b(unsigned int imm
, struct jit_ctx
*ctx
)
501 emit_bcond(MIPS_COND_ALL
, r_zero
, r_zero
, imm
, ctx
);
504 static inline void emit_jalr(unsigned int link
, unsigned int reg
,
507 emit_instr(ctx
, jalr
, link
, reg
);
510 static inline void emit_jr(unsigned int reg
, struct jit_ctx
*ctx
)
512 emit_instr(ctx
, jr
, reg
);
515 static inline u16
align_sp(unsigned int num
)
517 /* Double word alignment for 32-bit, quadword for 64-bit */
518 unsigned int align
= IS_ENABLED(CONFIG_64BIT
) ? 16 : 8;
519 num
= (num
+ (align
- 1)) & -align
;
523 static void save_bpf_jit_regs(struct jit_ctx
*ctx
, unsigned offset
)
525 int i
= 0, real_off
= 0;
526 u32 sflags
, tmp_flags
;
528 /* Adjust the stack pointer */
529 emit_stack_offset(-align_sp(offset
), ctx
);
531 tmp_flags
= sflags
= ctx
->flags
>> SEEN_SREG_SFT
;
532 /* sflags is essentially a bitmap */
534 if ((sflags
>> i
) & 0x1) {
535 emit_store_stack_reg(MIPS_R_S0
+ i
, r_sp
, real_off
,
543 /* save return address */
544 if (ctx
->flags
& SEEN_CALL
) {
545 emit_store_stack_reg(r_ra
, r_sp
, real_off
, ctx
);
549 /* Setup r_M leaving the alignment gap if necessary */
550 if (ctx
->flags
& SEEN_MEM
) {
551 if (real_off
% (SZREG
* 2))
553 emit_long_instr(ctx
, ADDIU
, r_M
, r_sp
, real_off
);
557 static void restore_bpf_jit_regs(struct jit_ctx
*ctx
,
561 u32 sflags
, tmp_flags
;
563 tmp_flags
= sflags
= ctx
->flags
>> SEEN_SREG_SFT
;
564 /* sflags is a bitmap */
567 if ((sflags
>> i
) & 0x1) {
568 emit_load_stack_reg(MIPS_R_S0
+ i
, r_sp
, real_off
,
576 /* restore return address */
577 if (ctx
->flags
& SEEN_CALL
)
578 emit_load_stack_reg(r_ra
, r_sp
, real_off
, ctx
);
580 /* Restore the sp and discard the scrach memory */
581 emit_stack_offset(align_sp(offset
), ctx
);
584 static unsigned int get_stack_depth(struct jit_ctx
*ctx
)
589 /* How may s* regs do we need to preserved? */
590 sp_off
+= hweight32(ctx
->flags
>> SEEN_SREG_SFT
) * SZREG
;
592 if (ctx
->flags
& SEEN_MEM
)
593 sp_off
+= 4 * BPF_MEMWORDS
; /* BPF_MEMWORDS are 32-bit */
595 if (ctx
->flags
& SEEN_CALL
)
596 sp_off
+= SZREG
; /* Space for our ra register */
601 static void build_prologue(struct jit_ctx
*ctx
)
605 /* Calculate the total offset for the stack pointer */
606 sp_off
= get_stack_depth(ctx
);
607 save_bpf_jit_regs(ctx
, sp_off
);
609 if (ctx
->flags
& SEEN_SKB
)
610 emit_reg_move(r_skb
, MIPS_R_A0
, ctx
);
612 if (ctx
->flags
& SEEN_SKB_DATA
) {
613 /* Load packet length */
614 emit_load(r_skb_len
, r_skb
, offsetof(struct sk_buff
, len
),
616 emit_load(r_tmp
, r_skb
, offsetof(struct sk_buff
, data_len
),
618 /* Load the data pointer */
619 emit_load_ptr(r_skb_data
, r_skb
,
620 offsetof(struct sk_buff
, data
), ctx
);
621 /* Load the header length */
622 emit_subu(r_skb_hl
, r_skb_len
, r_tmp
, ctx
);
625 if (ctx
->flags
& SEEN_X
)
626 emit_jit_reg_move(r_X
, r_zero
, ctx
);
628 /* Do not leak kernel data to userspace */
629 if (bpf_needs_clear_a(&ctx
->skf
->insns
[0]))
630 emit_jit_reg_move(r_A
, r_zero
, ctx
);
633 static void build_epilogue(struct jit_ctx
*ctx
)
637 /* Calculate the total offset for the stack pointer */
639 sp_off
= get_stack_depth(ctx
);
640 restore_bpf_jit_regs(ctx
, sp_off
);
647 #define CHOOSE_LOAD_FUNC(K, func) \
648 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative : func) : \
651 static int build_body(struct jit_ctx
*ctx
)
653 const struct bpf_prog
*prog
= ctx
->skf
;
654 const struct sock_filter
*inst
;
655 unsigned int i
, off
, condt
;
656 u32 k
, b_off __maybe_unused
;
657 u8 (*sk_load_func
)(unsigned long *skb
, int offset
);
659 for (i
= 0; i
< prog
->len
; i
++) {
662 inst
= &(prog
->insns
[i
]);
663 pr_debug("%s: code->0x%02x, jt->0x%x, jf->0x%x, k->0x%x\n",
664 __func__
, inst
->code
, inst
->jt
, inst
->jf
, inst
->k
);
666 code
= bpf_anc_helper(inst
);
668 if (ctx
->target
== NULL
)
669 ctx
->offsets
[i
] = ctx
->idx
* 4;
672 case BPF_LD
| BPF_IMM
:
673 /* A <- k ==> li r_A, k */
674 ctx
->flags
|= SEEN_A
;
675 emit_load_imm(r_A
, k
, ctx
);
677 case BPF_LD
| BPF_W
| BPF_LEN
:
678 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, len
) != 4);
679 /* A <- len ==> lw r_A, offset(skb) */
680 ctx
->flags
|= SEEN_SKB
| SEEN_A
;
681 off
= offsetof(struct sk_buff
, len
);
682 emit_load(r_A
, r_skb
, off
, ctx
);
684 case BPF_LD
| BPF_MEM
:
685 /* A <- M[k] ==> lw r_A, offset(M) */
686 ctx
->flags
|= SEEN_MEM
| SEEN_A
;
687 emit_load(r_A
, r_M
, SCRATCH_OFF(k
), ctx
);
689 case BPF_LD
| BPF_W
| BPF_ABS
:
691 sk_load_func
= CHOOSE_LOAD_FUNC(k
, sk_load_word
);
693 case BPF_LD
| BPF_H
| BPF_ABS
:
695 sk_load_func
= CHOOSE_LOAD_FUNC(k
, sk_load_half
);
697 case BPF_LD
| BPF_B
| BPF_ABS
:
699 sk_load_func
= CHOOSE_LOAD_FUNC(k
, sk_load_byte
);
701 emit_load_imm(r_off
, k
, ctx
);
703 ctx
->flags
|= SEEN_CALL
| SEEN_OFF
|
704 SEEN_SKB
| SEEN_A
| SEEN_SKB_DATA
;
706 emit_load_func(r_s0
, (ptr
)sk_load_func
, ctx
);
707 emit_reg_move(MIPS_R_A0
, r_skb
, ctx
);
708 emit_jalr(MIPS_R_RA
, r_s0
, ctx
);
709 /* Load second argument to delay slot */
710 emit_reg_move(MIPS_R_A1
, r_off
, ctx
);
711 /* Check the error value */
712 emit_bcond(MIPS_COND_EQ
, r_ret
, 0, b_imm(i
+ 1, ctx
),
714 /* Load return register on DS for failures */
715 emit_reg_move(r_ret
, r_zero
, ctx
);
716 /* Return with error */
717 emit_b(b_imm(prog
->len
, ctx
), ctx
);
720 case BPF_LD
| BPF_W
| BPF_IND
:
721 /* A <- P[X + k:4] */
722 sk_load_func
= sk_load_word
;
724 case BPF_LD
| BPF_H
| BPF_IND
:
725 /* A <- P[X + k:2] */
726 sk_load_func
= sk_load_half
;
728 case BPF_LD
| BPF_B
| BPF_IND
:
729 /* A <- P[X + k:1] */
730 sk_load_func
= sk_load_byte
;
732 ctx
->flags
|= SEEN_OFF
| SEEN_X
;
733 emit_addiu(r_off
, r_X
, k
, ctx
);
735 case BPF_LDX
| BPF_IMM
:
737 ctx
->flags
|= SEEN_X
;
738 emit_load_imm(r_X
, k
, ctx
);
740 case BPF_LDX
| BPF_MEM
:
742 ctx
->flags
|= SEEN_X
| SEEN_MEM
;
743 emit_load(r_X
, r_M
, SCRATCH_OFF(k
), ctx
);
745 case BPF_LDX
| BPF_W
| BPF_LEN
:
747 ctx
->flags
|= SEEN_X
| SEEN_SKB
;
748 off
= offsetof(struct sk_buff
, len
);
749 emit_load(r_X
, r_skb
, off
, ctx
);
751 case BPF_LDX
| BPF_B
| BPF_MSH
:
752 /* X <- 4 * (P[k:1] & 0xf) */
753 ctx
->flags
|= SEEN_X
| SEEN_CALL
| SEEN_SKB
;
754 /* Load offset to a1 */
755 emit_load_func(r_s0
, (ptr
)sk_load_byte
, ctx
);
757 * This may emit two instructions so it may not fit
758 * in the delay slot. So use a0 in the delay slot.
760 emit_load_imm(MIPS_R_A1
, k
, ctx
);
761 emit_jalr(MIPS_R_RA
, r_s0
, ctx
);
762 emit_reg_move(MIPS_R_A0
, r_skb
, ctx
); /* delay slot */
763 /* Check the error value */
764 emit_bcond(MIPS_COND_NE
, r_ret
, 0,
765 b_imm(prog
->len
, ctx
), ctx
);
766 emit_reg_move(r_ret
, r_zero
, ctx
);
768 /* X <- P[1:K] & 0xf */
769 emit_andi(r_X
, r_A
, 0xf, ctx
);
771 emit_b(b_imm(i
+ 1, ctx
), ctx
);
772 emit_sll(r_X
, r_X
, 2, ctx
); /* delay slot */
776 ctx
->flags
|= SEEN_MEM
| SEEN_A
;
777 emit_store(r_A
, r_M
, SCRATCH_OFF(k
), ctx
);
781 ctx
->flags
|= SEEN_MEM
| SEEN_X
;
782 emit_store(r_X
, r_M
, SCRATCH_OFF(k
), ctx
);
784 case BPF_ALU
| BPF_ADD
| BPF_K
:
786 ctx
->flags
|= SEEN_A
;
787 emit_addiu(r_A
, r_A
, k
, ctx
);
789 case BPF_ALU
| BPF_ADD
| BPF_X
:
791 ctx
->flags
|= SEEN_A
| SEEN_X
;
792 emit_addu(r_A
, r_A
, r_X
, ctx
);
794 case BPF_ALU
| BPF_SUB
| BPF_K
:
796 ctx
->flags
|= SEEN_A
;
797 emit_addiu(r_A
, r_A
, -k
, ctx
);
799 case BPF_ALU
| BPF_SUB
| BPF_X
:
801 ctx
->flags
|= SEEN_A
| SEEN_X
;
802 emit_subu(r_A
, r_A
, r_X
, ctx
);
804 case BPF_ALU
| BPF_MUL
| BPF_K
:
806 /* Load K to scratch register before MUL */
807 ctx
->flags
|= SEEN_A
;
808 emit_load_imm(r_s0
, k
, ctx
);
809 emit_mul(r_A
, r_A
, r_s0
, ctx
);
811 case BPF_ALU
| BPF_MUL
| BPF_X
:
813 ctx
->flags
|= SEEN_A
| SEEN_X
;
814 emit_mul(r_A
, r_A
, r_X
, ctx
);
816 case BPF_ALU
| BPF_DIV
| BPF_K
:
820 if (optimize_div(&k
)) {
821 ctx
->flags
|= SEEN_A
;
822 emit_srl(r_A
, r_A
, k
, ctx
);
825 ctx
->flags
|= SEEN_A
;
826 emit_load_imm(r_s0
, k
, ctx
);
827 emit_div(r_A
, r_s0
, ctx
);
829 case BPF_ALU
| BPF_MOD
| BPF_K
:
832 ctx
->flags
|= SEEN_A
;
833 emit_jit_reg_move(r_A
, r_zero
, ctx
);
835 ctx
->flags
|= SEEN_A
;
836 emit_load_imm(r_s0
, k
, ctx
);
837 emit_mod(r_A
, r_s0
, ctx
);
840 case BPF_ALU
| BPF_DIV
| BPF_X
:
842 ctx
->flags
|= SEEN_X
| SEEN_A
;
843 /* Check if r_X is zero */
844 emit_bcond(MIPS_COND_EQ
, r_X
, r_zero
,
845 b_imm(prog
->len
, ctx
), ctx
);
846 emit_load_imm(r_ret
, 0, ctx
); /* delay slot */
847 emit_div(r_A
, r_X
, ctx
);
849 case BPF_ALU
| BPF_MOD
| BPF_X
:
851 ctx
->flags
|= SEEN_X
| SEEN_A
;
852 /* Check if r_X is zero */
853 emit_bcond(MIPS_COND_EQ
, r_X
, r_zero
,
854 b_imm(prog
->len
, ctx
), ctx
);
855 emit_load_imm(r_ret
, 0, ctx
); /* delay slot */
856 emit_mod(r_A
, r_X
, ctx
);
858 case BPF_ALU
| BPF_OR
| BPF_K
:
860 ctx
->flags
|= SEEN_A
;
861 emit_ori(r_A
, r_A
, k
, ctx
);
863 case BPF_ALU
| BPF_OR
| BPF_X
:
865 ctx
->flags
|= SEEN_A
;
866 emit_ori(r_A
, r_A
, r_X
, ctx
);
868 case BPF_ALU
| BPF_XOR
| BPF_K
:
870 ctx
->flags
|= SEEN_A
;
871 emit_xori(r_A
, r_A
, k
, ctx
);
873 case BPF_ANC
| SKF_AD_ALU_XOR_X
:
874 case BPF_ALU
| BPF_XOR
| BPF_X
:
876 ctx
->flags
|= SEEN_A
;
877 emit_xor(r_A
, r_A
, r_X
, ctx
);
879 case BPF_ALU
| BPF_AND
| BPF_K
:
881 ctx
->flags
|= SEEN_A
;
882 emit_andi(r_A
, r_A
, k
, ctx
);
884 case BPF_ALU
| BPF_AND
| BPF_X
:
886 ctx
->flags
|= SEEN_A
| SEEN_X
;
887 emit_and(r_A
, r_A
, r_X
, ctx
);
889 case BPF_ALU
| BPF_LSH
| BPF_K
:
891 ctx
->flags
|= SEEN_A
;
892 emit_sll(r_A
, r_A
, k
, ctx
);
894 case BPF_ALU
| BPF_LSH
| BPF_X
:
896 ctx
->flags
|= SEEN_A
| SEEN_X
;
897 emit_sllv(r_A
, r_A
, r_X
, ctx
);
899 case BPF_ALU
| BPF_RSH
| BPF_K
:
901 ctx
->flags
|= SEEN_A
;
902 emit_srl(r_A
, r_A
, k
, ctx
);
904 case BPF_ALU
| BPF_RSH
| BPF_X
:
905 ctx
->flags
|= SEEN_A
| SEEN_X
;
906 emit_srlv(r_A
, r_A
, r_X
, ctx
);
908 case BPF_ALU
| BPF_NEG
:
910 ctx
->flags
|= SEEN_A
;
913 case BPF_JMP
| BPF_JA
:
915 emit_b(b_imm(i
+ k
+ 1, ctx
), ctx
);
918 case BPF_JMP
| BPF_JEQ
| BPF_K
:
919 /* pc += ( A == K ) ? pc->jt : pc->jf */
920 condt
= MIPS_COND_EQ
| MIPS_COND_K
;
922 case BPF_JMP
| BPF_JEQ
| BPF_X
:
923 ctx
->flags
|= SEEN_X
;
924 /* pc += ( A == X ) ? pc->jt : pc->jf */
925 condt
= MIPS_COND_EQ
| MIPS_COND_X
;
927 case BPF_JMP
| BPF_JGE
| BPF_K
:
928 /* pc += ( A >= K ) ? pc->jt : pc->jf */
929 condt
= MIPS_COND_GE
| MIPS_COND_K
;
931 case BPF_JMP
| BPF_JGE
| BPF_X
:
932 ctx
->flags
|= SEEN_X
;
933 /* pc += ( A >= X ) ? pc->jt : pc->jf */
934 condt
= MIPS_COND_GE
| MIPS_COND_X
;
936 case BPF_JMP
| BPF_JGT
| BPF_K
:
937 /* pc += ( A > K ) ? pc->jt : pc->jf */
938 condt
= MIPS_COND_GT
| MIPS_COND_K
;
940 case BPF_JMP
| BPF_JGT
| BPF_X
:
941 ctx
->flags
|= SEEN_X
;
942 /* pc += ( A > X ) ? pc->jt : pc->jf */
943 condt
= MIPS_COND_GT
| MIPS_COND_X
;
945 /* Greater or Equal */
946 if ((condt
& MIPS_COND_GE
) ||
947 (condt
& MIPS_COND_GT
)) {
948 if (condt
& MIPS_COND_K
) { /* K */
949 ctx
->flags
|= SEEN_A
;
950 emit_sltiu(r_s0
, r_A
, k
, ctx
);
952 ctx
->flags
|= SEEN_A
|
954 emit_sltu(r_s0
, r_A
, r_X
, ctx
);
956 /* A < (K|X) ? r_scrach = 1 */
957 b_off
= b_imm(i
+ inst
->jf
+ 1, ctx
);
958 emit_bcond(MIPS_COND_NE
, r_s0
, r_zero
, b_off
,
961 /* A > (K|X) ? scratch = 0 */
962 if (condt
& MIPS_COND_GT
) {
963 /* Checking for equality */
964 ctx
->flags
|= SEEN_A
| SEEN_X
;
965 if (condt
& MIPS_COND_K
)
966 emit_load_imm(r_s0
, k
, ctx
);
968 emit_jit_reg_move(r_s0
, r_X
,
970 b_off
= b_imm(i
+ inst
->jf
+ 1, ctx
);
971 emit_bcond(MIPS_COND_EQ
, r_A
, r_s0
,
974 /* Finally, A > K|X */
975 b_off
= b_imm(i
+ inst
->jt
+ 1, ctx
);
979 /* A >= (K|X) so jump */
980 b_off
= b_imm(i
+ inst
->jt
+ 1, ctx
);
986 if (condt
& MIPS_COND_K
) { /* K */
987 ctx
->flags
|= SEEN_A
;
988 emit_load_imm(r_s0
, k
, ctx
);
990 b_off
= b_imm(i
+ inst
->jt
+ 1, ctx
);
991 emit_bcond(MIPS_COND_EQ
, r_A
, r_s0
,
995 b_off
= b_imm(i
+ inst
->jf
+ 1,
997 emit_bcond(MIPS_COND_NE
, r_A
, r_s0
,
1002 ctx
->flags
|= SEEN_A
| SEEN_X
;
1003 b_off
= b_imm(i
+ inst
->jt
+ 1,
1005 emit_bcond(MIPS_COND_EQ
, r_A
, r_X
,
1009 b_off
= b_imm(i
+ inst
->jf
+ 1, ctx
);
1010 emit_bcond(MIPS_COND_NE
, r_A
, r_X
,
1016 case BPF_JMP
| BPF_JSET
| BPF_K
:
1017 ctx
->flags
|= SEEN_A
;
1018 /* pc += (A & K) ? pc -> jt : pc -> jf */
1019 emit_load_imm(r_s1
, k
, ctx
);
1020 emit_and(r_s0
, r_A
, r_s1
, ctx
);
1022 b_off
= b_imm(i
+ inst
->jt
+ 1, ctx
);
1023 emit_bcond(MIPS_COND_NE
, r_s0
, r_zero
, b_off
, ctx
);
1026 b_off
= b_imm(i
+ inst
->jf
+ 1, ctx
);
1030 case BPF_JMP
| BPF_JSET
| BPF_X
:
1031 ctx
->flags
|= SEEN_X
| SEEN_A
;
1032 /* pc += (A & X) ? pc -> jt : pc -> jf */
1033 emit_and(r_s0
, r_A
, r_X
, ctx
);
1035 b_off
= b_imm(i
+ inst
->jt
+ 1, ctx
);
1036 emit_bcond(MIPS_COND_NE
, r_s0
, r_zero
, b_off
, ctx
);
1039 b_off
= b_imm(i
+ inst
->jf
+ 1, ctx
);
1043 case BPF_RET
| BPF_A
:
1044 ctx
->flags
|= SEEN_A
;
1045 if (i
!= prog
->len
- 1)
1047 * If this is not the last instruction
1048 * then jump to the epilogue
1050 emit_b(b_imm(prog
->len
, ctx
), ctx
);
1051 emit_reg_move(r_ret
, r_A
, ctx
); /* delay slot */
1053 case BPF_RET
| BPF_K
:
1055 * It can emit two instructions so it does not fit on
1058 emit_load_imm(r_ret
, k
, ctx
);
1059 if (i
!= prog
->len
- 1) {
1061 * If this is not the last instruction
1062 * then jump to the epilogue
1064 emit_b(b_imm(prog
->len
, ctx
), ctx
);
1068 case BPF_MISC
| BPF_TAX
:
1070 ctx
->flags
|= SEEN_X
| SEEN_A
;
1071 emit_jit_reg_move(r_X
, r_A
, ctx
);
1073 case BPF_MISC
| BPF_TXA
:
1075 ctx
->flags
|= SEEN_A
| SEEN_X
;
1076 emit_jit_reg_move(r_A
, r_X
, ctx
);
1079 case BPF_ANC
| SKF_AD_PROTOCOL
:
1080 /* A = ntohs(skb->protocol */
1081 ctx
->flags
|= SEEN_SKB
| SEEN_OFF
| SEEN_A
;
1082 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
,
1084 off
= offsetof(struct sk_buff
, protocol
);
1085 emit_half_load(r_A
, r_skb
, off
, ctx
);
1086 #ifdef CONFIG_CPU_LITTLE_ENDIAN
1087 /* This needs little endian fixup */
1089 /* R2 and later have the wsbh instruction */
1090 emit_wsbh(r_A
, r_A
, ctx
);
1092 /* Get first byte */
1093 emit_andi(r_tmp_imm
, r_A
, 0xff, ctx
);
1095 emit_sll(r_tmp
, r_tmp_imm
, 8, ctx
);
1096 /* Get second byte */
1097 emit_srl(r_tmp_imm
, r_A
, 8, ctx
);
1098 emit_andi(r_tmp_imm
, r_tmp_imm
, 0xff, ctx
);
1099 /* Put everyting together in r_A */
1100 emit_or(r_A
, r_tmp
, r_tmp_imm
, ctx
);
1104 case BPF_ANC
| SKF_AD_CPU
:
1105 ctx
->flags
|= SEEN_A
| SEEN_OFF
;
1106 /* A = current_thread_info()->cpu */
1107 BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info
,
1109 off
= offsetof(struct thread_info
, cpu
);
1110 /* $28/gp points to the thread_info struct */
1111 emit_load(r_A
, 28, off
, ctx
);
1113 case BPF_ANC
| SKF_AD_IFINDEX
:
1114 /* A = skb->dev->ifindex */
1115 ctx
->flags
|= SEEN_SKB
| SEEN_A
;
1116 off
= offsetof(struct sk_buff
, dev
);
1117 /* Load *dev pointer */
1118 emit_load_ptr(r_s0
, r_skb
, off
, ctx
);
1119 /* error (0) in the delay slot */
1120 emit_bcond(MIPS_COND_EQ
, r_s0
, r_zero
,
1121 b_imm(prog
->len
, ctx
), ctx
);
1122 emit_reg_move(r_ret
, r_zero
, ctx
);
1123 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device
,
1125 off
= offsetof(struct net_device
, ifindex
);
1126 emit_load(r_A
, r_s0
, off
, ctx
);
1128 case BPF_ANC
| SKF_AD_MARK
:
1129 ctx
->flags
|= SEEN_SKB
| SEEN_A
;
1130 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, mark
) != 4);
1131 off
= offsetof(struct sk_buff
, mark
);
1132 emit_load(r_A
, r_skb
, off
, ctx
);
1134 case BPF_ANC
| SKF_AD_RXHASH
:
1135 ctx
->flags
|= SEEN_SKB
| SEEN_A
;
1136 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, hash
) != 4);
1137 off
= offsetof(struct sk_buff
, hash
);
1138 emit_load(r_A
, r_skb
, off
, ctx
);
1140 case BPF_ANC
| SKF_AD_VLAN_TAG
:
1141 case BPF_ANC
| SKF_AD_VLAN_TAG_PRESENT
:
1142 ctx
->flags
|= SEEN_SKB
| SEEN_A
;
1143 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
,
1145 off
= offsetof(struct sk_buff
, vlan_tci
);
1146 emit_half_load(r_s0
, r_skb
, off
, ctx
);
1147 if (code
== (BPF_ANC
| SKF_AD_VLAN_TAG
)) {
1148 emit_andi(r_A
, r_s0
, (u16
)~VLAN_TAG_PRESENT
, ctx
);
1150 emit_andi(r_A
, r_s0
, VLAN_TAG_PRESENT
, ctx
);
1151 /* return 1 if present */
1152 emit_sltu(r_A
, r_zero
, r_A
, ctx
);
1155 case BPF_ANC
| SKF_AD_PKTTYPE
:
1156 ctx
->flags
|= SEEN_SKB
;
1158 emit_load_byte(r_tmp
, r_skb
, PKT_TYPE_OFFSET(), ctx
);
1159 /* Keep only the last 3 bits */
1160 emit_andi(r_A
, r_tmp
, PKT_TYPE_MAX
, ctx
);
1161 #ifdef __BIG_ENDIAN_BITFIELD
1162 /* Get the actual packet type to the lower 3 bits */
1163 emit_srl(r_A
, r_A
, 5, ctx
);
1166 case BPF_ANC
| SKF_AD_QUEUE
:
1167 ctx
->flags
|= SEEN_SKB
| SEEN_A
;
1168 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
,
1169 queue_mapping
) != 2);
1170 BUILD_BUG_ON(offsetof(struct sk_buff
,
1171 queue_mapping
) > 0xff);
1172 off
= offsetof(struct sk_buff
, queue_mapping
);
1173 emit_half_load(r_A
, r_skb
, off
, ctx
);
1176 pr_debug("%s: Unhandled opcode: 0x%02x\n", __FILE__
,
1182 /* compute offsets only during the first pass */
1183 if (ctx
->target
== NULL
)
1184 ctx
->offsets
[i
] = ctx
->idx
* 4;
1189 int bpf_jit_enable __read_mostly
;
1191 void bpf_jit_compile(struct bpf_prog
*fp
)
1194 unsigned int alloc_size
, tmp_idx
;
1196 if (!bpf_jit_enable
)
1199 memset(&ctx
, 0, sizeof(ctx
));
1201 ctx
.offsets
= kcalloc(fp
->len
+ 1, sizeof(*ctx
.offsets
), GFP_KERNEL
);
1202 if (ctx
.offsets
== NULL
)
1207 if (build_body(&ctx
))
1211 build_prologue(&ctx
);
1212 ctx
.prologue_bytes
= (ctx
.idx
- tmp_idx
) * 4;
1213 /* just to complete the ctx.idx count */
1214 build_epilogue(&ctx
);
1216 alloc_size
= 4 * ctx
.idx
;
1217 ctx
.target
= module_alloc(alloc_size
);
1218 if (ctx
.target
== NULL
)
1222 memset(ctx
.target
, 0, alloc_size
);
1226 /* Generate the actual JIT code */
1227 build_prologue(&ctx
);
1229 build_epilogue(&ctx
);
1231 /* Update the icache */
1232 flush_icache_range((ptr
)ctx
.target
, (ptr
)(ctx
.target
+ ctx
.idx
));
1234 if (bpf_jit_enable
> 1)
1236 bpf_jit_dump(fp
->len
, alloc_size
, 2, ctx
.target
);
1238 fp
->bpf_func
= (void *)ctx
.target
;
1245 void bpf_jit_free(struct bpf_prog
*fp
)
1248 module_memfree(fp
->bpf_func
);
1250 bpf_prog_unlock_free(fp
);