1 /*
2 * Just-In-Time compiler for BPF filters on MIPS
3 *
4 * Copyright (c) 2014 Imagination Technologies Ltd.
5 * Author: Markos Chandras <markos.chandras@imgtec.com>
6 *
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.
10 */
11
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/kconfig.h>
18 #include <linux/moduleloader.h>
19 #include <linux/netdevice.h>
20 #include <linux/string.h>
21 #include <linux/slab.h>
22 #include <linux/types.h>
23 #include <asm/bitops.h>
24 #include <asm/cacheflush.h>
25 #include <asm/cpu-features.h>
26 #include <asm/uasm.h>
27
28 #include "bpf_jit.h"
29
30 /* ABI
31 *
32 * s0 1st scratch register
33 * s1 2nd scratch register
34 * s2 offset register
35 * s3 BPF register A
36 * s4 BPF register X
37 * s5 *skb
38 * s6 *scratch memory
39 *
40 * On entry (*bpf_func)(*skb, *filter)
41 * a0 = MIPS_R_A0 = skb;
42 * a1 = MIPS_R_A1 = filter;
43 *
44 * Stack
45 * ...
46 * M[15]
47 * M[14]
48 * M[13]
49 * ...
50 * M[0] <-- r_M
51 * saved reg k-1
52 * saved reg k-2
53 * ...
54 * saved reg 0 <-- r_sp
55 * <no argument area>
56 *
57 * Packet layout
58 *
59 * <--------------------- len ------------------------>
60 * <--skb-len(r_skb_hl)-->< ----- skb->data_len ------>
61 * ----------------------------------------------------
62 * | skb->data |
63 * ----------------------------------------------------
64 */
65
66 #define RSIZE (sizeof(unsigned long))
67 #define ptr typeof(unsigned long)
68
69 /* ABI specific return values */
70 #ifdef CONFIG_32BIT /* O32 */
71 #ifdef CONFIG_CPU_LITTLE_ENDIAN
72 #define r_err MIPS_R_V1
73 #define r_val MIPS_R_V0
74 #else /* CONFIG_CPU_LITTLE_ENDIAN */
75 #define r_err MIPS_R_V0
76 #define r_val MIPS_R_V1
77 #endif
78 #else /* N64 */
79 #define r_err MIPS_R_V0
80 #define r_val MIPS_R_V0
81 #endif
82
83 #define r_ret MIPS_R_V0
84
85 /*
86 * Use 2 scratch registers to avoid pipeline interlocks.
87 * There is no overhead during epilogue and prologue since
88 * any of the $s0-$s6 registers will only be preserved if
89 * they are going to actually be used.
90 */
91 #define r_s0 MIPS_R_S0 /* scratch reg 1 */
92 #define r_s1 MIPS_R_S1 /* scratch reg 2 */
93 #define r_off MIPS_R_S2
94 #define r_A MIPS_R_S3
95 #define r_X MIPS_R_S4
96 #define r_skb MIPS_R_S5
97 #define r_M MIPS_R_S6
98 #define r_tmp_imm MIPS_R_T6 /* No need to preserve this */
99 #define r_tmp MIPS_R_T7 /* No need to preserve this */
100 #define r_zero MIPS_R_ZERO
101 #define r_sp MIPS_R_SP
102 #define r_ra MIPS_R_RA
103
104 #define SCRATCH_OFF(k) (4 * (k))
105
106 /* JIT flags */
107 #define SEEN_CALL (1 << BPF_MEMWORDS)
108 #define SEEN_SREG_SFT (BPF_MEMWORDS + 1)
109 #define SEEN_SREG_BASE (1 << SEEN_SREG_SFT)
110 #define SEEN_SREG(x) (SEEN_SREG_BASE << (x))
111 #define SEEN_S0 SEEN_SREG(0)
112 #define SEEN_S1 SEEN_SREG(1)
113 #define SEEN_OFF SEEN_SREG(2)
114 #define SEEN_A SEEN_SREG(3)
115 #define SEEN_X SEEN_SREG(4)
116 #define SEEN_SKB SEEN_SREG(5)
117 #define SEEN_MEM SEEN_SREG(6)
118
119 /* Arguments used by JIT */
120 #define ARGS_USED_BY_JIT 2 /* only applicable to 64-bit */
121
122 #define SBIT(x) (1 << (x)) /* Signed version of BIT() */
123
124 /**
125 * struct jit_ctx - JIT context
126 * @skf: The sk_filter
127 * @prologue_bytes: Number of bytes for prologue
128 * @idx: Instruction index
129 * @flags: JIT flags
130 * @offsets: Instruction offsets
131 * @target: Memory location for the compiled filter
132 */
133 struct jit_ctx {
134 const struct bpf_prog *skf;
135 unsigned int prologue_bytes;
136 u32 idx;
137 u32 flags;
138 u32 *offsets;
139 u32 *target;
140 };
141
142
optimize_div(u32 * k)143 static inline int optimize_div(u32 *k)
144 {
145 /* power of 2 divides can be implemented with right shift */
146 if (!(*k & (*k-1))) {
147 *k = ilog2(*k);
148 return 1;
149 }
150
151 return 0;
152 }
153
154 static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx);
155
156 /* Simply emit the instruction if the JIT memory space has been allocated */
157 #define emit_instr(ctx, func, ...) \
158 do { \
159 if ((ctx)->target != NULL) { \
160 u32 *p = &(ctx)->target[ctx->idx]; \
161 uasm_i_##func(&p, ##__VA_ARGS__); \
162 } \
163 (ctx)->idx++; \
164 } while (0)
165
166 /*
167 * Similar to emit_instr but it must be used when we need to emit
168 * 32-bit or 64-bit instructions
169 */
170 #define emit_long_instr(ctx, func, ...) \
171 do { \
172 if ((ctx)->target != NULL) { \
173 u32 *p = &(ctx)->target[ctx->idx]; \
174 UASM_i_##func(&p, ##__VA_ARGS__); \
175 } \
176 (ctx)->idx++; \
177 } while (0)
178
179 /* Determine if immediate is within the 16-bit signed range */
is_range16(s32 imm)180 static inline bool is_range16(s32 imm)
181 {
182 return !(imm >= SBIT(15) || imm < -SBIT(15));
183 }
184
emit_addu(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)185 static inline void emit_addu(unsigned int dst, unsigned int src1,
186 unsigned int src2, struct jit_ctx *ctx)
187 {
188 emit_instr(ctx, addu, dst, src1, src2);
189 }
190
emit_nop(struct jit_ctx * ctx)191 static inline void emit_nop(struct jit_ctx *ctx)
192 {
193 emit_instr(ctx, nop);
194 }
195
196 /* Load a u32 immediate to a register */
emit_load_imm(unsigned int dst,u32 imm,struct jit_ctx * ctx)197 static inline void emit_load_imm(unsigned int dst, u32 imm, struct jit_ctx *ctx)
198 {
199 if (ctx->target != NULL) {
200 /* addiu can only handle s16 */
201 if (!is_range16(imm)) {
202 u32 *p = &ctx->target[ctx->idx];
203 uasm_i_lui(&p, r_tmp_imm, (s32)imm >> 16);
204 p = &ctx->target[ctx->idx + 1];
205 uasm_i_ori(&p, dst, r_tmp_imm, imm & 0xffff);
206 } else {
207 u32 *p = &ctx->target[ctx->idx];
208 uasm_i_addiu(&p, dst, r_zero, imm);
209 }
210 }
211 ctx->idx++;
212
213 if (!is_range16(imm))
214 ctx->idx++;
215 }
216
emit_or(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)217 static inline void emit_or(unsigned int dst, unsigned int src1,
218 unsigned int src2, struct jit_ctx *ctx)
219 {
220 emit_instr(ctx, or, dst, src1, src2);
221 }
222
emit_ori(unsigned int dst,unsigned src,u32 imm,struct jit_ctx * ctx)223 static inline void emit_ori(unsigned int dst, unsigned src, u32 imm,
224 struct jit_ctx *ctx)
225 {
226 if (imm >= BIT(16)) {
227 emit_load_imm(r_tmp, imm, ctx);
228 emit_or(dst, src, r_tmp, ctx);
229 } else {
230 emit_instr(ctx, ori, dst, src, imm);
231 }
232 }
233
emit_daddiu(unsigned int dst,unsigned int src,int imm,struct jit_ctx * ctx)234 static inline void emit_daddiu(unsigned int dst, unsigned int src,
235 int imm, struct jit_ctx *ctx)
236 {
237 /*
238 * Only used for stack, so the imm is relatively small
239 * and it fits in 15-bits
240 */
241 emit_instr(ctx, daddiu, dst, src, imm);
242 }
243
emit_addiu(unsigned int dst,unsigned int src,u32 imm,struct jit_ctx * ctx)244 static inline void emit_addiu(unsigned int dst, unsigned int src,
245 u32 imm, struct jit_ctx *ctx)
246 {
247 if (!is_range16(imm)) {
248 emit_load_imm(r_tmp, imm, ctx);
249 emit_addu(dst, r_tmp, src, ctx);
250 } else {
251 emit_instr(ctx, addiu, dst, src, imm);
252 }
253 }
254
emit_and(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)255 static inline void emit_and(unsigned int dst, unsigned int src1,
256 unsigned int src2, struct jit_ctx *ctx)
257 {
258 emit_instr(ctx, and, dst, src1, src2);
259 }
260
emit_andi(unsigned int dst,unsigned int src,u32 imm,struct jit_ctx * ctx)261 static inline void emit_andi(unsigned int dst, unsigned int src,
262 u32 imm, struct jit_ctx *ctx)
263 {
264 /* If imm does not fit in u16 then load it to register */
265 if (imm >= BIT(16)) {
266 emit_load_imm(r_tmp, imm, ctx);
267 emit_and(dst, src, r_tmp, ctx);
268 } else {
269 emit_instr(ctx, andi, dst, src, imm);
270 }
271 }
272
emit_xor(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)273 static inline void emit_xor(unsigned int dst, unsigned int src1,
274 unsigned int src2, struct jit_ctx *ctx)
275 {
276 emit_instr(ctx, xor, dst, src1, src2);
277 }
278
emit_xori(ptr dst,ptr src,u32 imm,struct jit_ctx * ctx)279 static inline void emit_xori(ptr dst, ptr src, u32 imm, struct jit_ctx *ctx)
280 {
281 /* If imm does not fit in u16 then load it to register */
282 if (imm >= BIT(16)) {
283 emit_load_imm(r_tmp, imm, ctx);
284 emit_xor(dst, src, r_tmp, ctx);
285 } else {
286 emit_instr(ctx, xori, dst, src, imm);
287 }
288 }
289
emit_stack_offset(int offset,struct jit_ctx * ctx)290 static inline void emit_stack_offset(int offset, struct jit_ctx *ctx)
291 {
292 emit_long_instr(ctx, ADDIU, r_sp, r_sp, offset);
293 }
294
emit_subu(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)295 static inline void emit_subu(unsigned int dst, unsigned int src1,
296 unsigned int src2, struct jit_ctx *ctx)
297 {
298 emit_instr(ctx, subu, dst, src1, src2);
299 }
300
emit_neg(unsigned int reg,struct jit_ctx * ctx)301 static inline void emit_neg(unsigned int reg, struct jit_ctx *ctx)
302 {
303 emit_subu(reg, r_zero, reg, ctx);
304 }
305
emit_sllv(unsigned int dst,unsigned int src,unsigned int sa,struct jit_ctx * ctx)306 static inline void emit_sllv(unsigned int dst, unsigned int src,
307 unsigned int sa, struct jit_ctx *ctx)
308 {
309 emit_instr(ctx, sllv, dst, src, sa);
310 }
311
emit_sll(unsigned int dst,unsigned int src,unsigned int sa,struct jit_ctx * ctx)312 static inline void emit_sll(unsigned int dst, unsigned int src,
313 unsigned int sa, struct jit_ctx *ctx)
314 {
315 /* sa is 5-bits long */
316 if (sa >= BIT(5))
317 /* Shifting >= 32 results in zero */
318 emit_jit_reg_move(dst, r_zero, ctx);
319 else
320 emit_instr(ctx, sll, dst, src, sa);
321 }
322
emit_srlv(unsigned int dst,unsigned int src,unsigned int sa,struct jit_ctx * ctx)323 static inline void emit_srlv(unsigned int dst, unsigned int src,
324 unsigned int sa, struct jit_ctx *ctx)
325 {
326 emit_instr(ctx, srlv, dst, src, sa);
327 }
328
emit_srl(unsigned int dst,unsigned int src,unsigned int sa,struct jit_ctx * ctx)329 static inline void emit_srl(unsigned int dst, unsigned int src,
330 unsigned int sa, struct jit_ctx *ctx)
331 {
332 /* sa is 5-bits long */
333 if (sa >= BIT(5))
334 /* Shifting >= 32 results in zero */
335 emit_jit_reg_move(dst, r_zero, ctx);
336 else
337 emit_instr(ctx, srl, dst, src, sa);
338 }
339
emit_slt(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)340 static inline void emit_slt(unsigned int dst, unsigned int src1,
341 unsigned int src2, struct jit_ctx *ctx)
342 {
343 emit_instr(ctx, slt, dst, src1, src2);
344 }
345
emit_sltu(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)346 static inline void emit_sltu(unsigned int dst, unsigned int src1,
347 unsigned int src2, struct jit_ctx *ctx)
348 {
349 emit_instr(ctx, sltu, dst, src1, src2);
350 }
351
emit_sltiu(unsigned dst,unsigned int src,unsigned int imm,struct jit_ctx * ctx)352 static inline void emit_sltiu(unsigned dst, unsigned int src,
353 unsigned int imm, struct jit_ctx *ctx)
354 {
355 /* 16 bit immediate */
356 if (!is_range16((s32)imm)) {
357 emit_load_imm(r_tmp, imm, ctx);
358 emit_sltu(dst, src, r_tmp, ctx);
359 } else {
360 emit_instr(ctx, sltiu, dst, src, imm);
361 }
362
363 }
364
365 /* Store register on the stack */
emit_store_stack_reg(ptr reg,ptr base,unsigned int offset,struct jit_ctx * ctx)366 static inline void emit_store_stack_reg(ptr reg, ptr base,
367 unsigned int offset,
368 struct jit_ctx *ctx)
369 {
370 emit_long_instr(ctx, SW, reg, offset, base);
371 }
372
emit_store(ptr reg,ptr base,unsigned int offset,struct jit_ctx * ctx)373 static inline void emit_store(ptr reg, ptr base, unsigned int offset,
374 struct jit_ctx *ctx)
375 {
376 emit_instr(ctx, sw, reg, offset, base);
377 }
378
emit_load_stack_reg(ptr reg,ptr base,unsigned int offset,struct jit_ctx * ctx)379 static inline void emit_load_stack_reg(ptr reg, ptr base,
380 unsigned int offset,
381 struct jit_ctx *ctx)
382 {
383 emit_long_instr(ctx, LW, reg, offset, base);
384 }
385
emit_load(unsigned int reg,unsigned int base,unsigned int offset,struct jit_ctx * ctx)386 static inline void emit_load(unsigned int reg, unsigned int base,
387 unsigned int offset, struct jit_ctx *ctx)
388 {
389 emit_instr(ctx, lw, reg, offset, base);
390 }
391
emit_load_byte(unsigned int reg,unsigned int base,unsigned int offset,struct jit_ctx * ctx)392 static inline void emit_load_byte(unsigned int reg, unsigned int base,
393 unsigned int offset, struct jit_ctx *ctx)
394 {
395 emit_instr(ctx, lb, reg, offset, base);
396 }
397
emit_half_load(unsigned int reg,unsigned int base,unsigned int offset,struct jit_ctx * ctx)398 static inline void emit_half_load(unsigned int reg, unsigned int base,
399 unsigned int offset, struct jit_ctx *ctx)
400 {
401 emit_instr(ctx, lh, reg, offset, base);
402 }
403
emit_mul(unsigned int dst,unsigned int src1,unsigned int src2,struct jit_ctx * ctx)404 static inline void emit_mul(unsigned int dst, unsigned int src1,
405 unsigned int src2, struct jit_ctx *ctx)
406 {
407 emit_instr(ctx, mul, dst, src1, src2);
408 }
409
emit_div(unsigned int dst,unsigned int src,struct jit_ctx * ctx)410 static inline void emit_div(unsigned int dst, unsigned int src,
411 struct jit_ctx *ctx)
412 {
413 if (ctx->target != NULL) {
414 u32 *p = &ctx->target[ctx->idx];
415 uasm_i_divu(&p, dst, src);
416 p = &ctx->target[ctx->idx + 1];
417 uasm_i_mflo(&p, dst);
418 }
419 ctx->idx += 2; /* 2 insts */
420 }
421
emit_mod(unsigned int dst,unsigned int src,struct jit_ctx * ctx)422 static inline void emit_mod(unsigned int dst, unsigned int src,
423 struct jit_ctx *ctx)
424 {
425 if (ctx->target != NULL) {
426 u32 *p = &ctx->target[ctx->idx];
427 uasm_i_divu(&p, dst, src);
428 p = &ctx->target[ctx->idx + 1];
429 uasm_i_mfhi(&p, dst);
430 }
431 ctx->idx += 2; /* 2 insts */
432 }
433
emit_dsll(unsigned int dst,unsigned int src,unsigned int sa,struct jit_ctx * ctx)434 static inline void emit_dsll(unsigned int dst, unsigned int src,
435 unsigned int sa, struct jit_ctx *ctx)
436 {
437 emit_instr(ctx, dsll, dst, src, sa);
438 }
439
emit_dsrl32(unsigned int dst,unsigned int src,unsigned int sa,struct jit_ctx * ctx)440 static inline void emit_dsrl32(unsigned int dst, unsigned int src,
441 unsigned int sa, struct jit_ctx *ctx)
442 {
443 emit_instr(ctx, dsrl32, dst, src, sa);
444 }
445
emit_wsbh(unsigned int dst,unsigned int src,struct jit_ctx * ctx)446 static inline void emit_wsbh(unsigned int dst, unsigned int src,
447 struct jit_ctx *ctx)
448 {
449 emit_instr(ctx, wsbh, dst, src);
450 }
451
452 /* load pointer to register */
emit_load_ptr(unsigned int dst,unsigned int src,int imm,struct jit_ctx * ctx)453 static inline void emit_load_ptr(unsigned int dst, unsigned int src,
454 int imm, struct jit_ctx *ctx)
455 {
456 /* src contains the base addr of the 32/64-pointer */
457 emit_long_instr(ctx, LW, dst, imm, src);
458 }
459
460 /* load a function pointer to register */
emit_load_func(unsigned int reg,ptr imm,struct jit_ctx * ctx)461 static inline void emit_load_func(unsigned int reg, ptr imm,
462 struct jit_ctx *ctx)
463 {
464 if (config_enabled(CONFIG_64BIT)) {
465 /* At this point imm is always 64-bit */
466 emit_load_imm(r_tmp, (u64)imm >> 32, ctx);
467 emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */
468 emit_ori(r_tmp, r_tmp_imm, (imm >> 16) & 0xffff, ctx);
469 emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */
470 emit_ori(reg, r_tmp_imm, imm & 0xffff, ctx);
471 } else {
472 emit_load_imm(reg, imm, ctx);
473 }
474 }
475
476 /* Move to real MIPS register */
emit_reg_move(ptr dst,ptr src,struct jit_ctx * ctx)477 static inline void emit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx)
478 {
479 emit_long_instr(ctx, ADDU, dst, src, r_zero);
480 }
481
482 /* Move to JIT (32-bit) register */
emit_jit_reg_move(ptr dst,ptr src,struct jit_ctx * ctx)483 static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx)
484 {
485 emit_addu(dst, src, r_zero, ctx);
486 }
487
488 /* Compute the immediate value for PC-relative branches. */
b_imm(unsigned int tgt,struct jit_ctx * ctx)489 static inline u32 b_imm(unsigned int tgt, struct jit_ctx *ctx)
490 {
491 if (ctx->target == NULL)
492 return 0;
493
494 /*
495 * We want a pc-relative branch. We only do forward branches
496 * so tgt is always after pc. tgt is the instruction offset
497 * we want to jump to.
498
499 * Branch on MIPS:
500 * I: target_offset <- sign_extend(offset)
501 * I+1: PC += target_offset (delay slot)
502 *
503 * ctx->idx currently points to the branch instruction
504 * but the offset is added to the delay slot so we need
505 * to subtract 4.
506 */
507 return ctx->offsets[tgt] -
508 (ctx->idx * 4 - ctx->prologue_bytes) - 4;
509 }
510
emit_bcond(int cond,unsigned int reg1,unsigned int reg2,unsigned int imm,struct jit_ctx * ctx)511 static inline void emit_bcond(int cond, unsigned int reg1, unsigned int reg2,
512 unsigned int imm, struct jit_ctx *ctx)
513 {
514 if (ctx->target != NULL) {
515 u32 *p = &ctx->target[ctx->idx];
516
517 switch (cond) {
518 case MIPS_COND_EQ:
519 uasm_i_beq(&p, reg1, reg2, imm);
520 break;
521 case MIPS_COND_NE:
522 uasm_i_bne(&p, reg1, reg2, imm);
523 break;
524 case MIPS_COND_ALL:
525 uasm_i_b(&p, imm);
526 break;
527 default:
528 pr_warn("%s: Unhandled branch conditional: %d\n",
529 __func__, cond);
530 }
531 }
532 ctx->idx++;
533 }
534
emit_b(unsigned int imm,struct jit_ctx * ctx)535 static inline void emit_b(unsigned int imm, struct jit_ctx *ctx)
536 {
537 emit_bcond(MIPS_COND_ALL, r_zero, r_zero, imm, ctx);
538 }
539
emit_jalr(unsigned int link,unsigned int reg,struct jit_ctx * ctx)540 static inline void emit_jalr(unsigned int link, unsigned int reg,
541 struct jit_ctx *ctx)
542 {
543 emit_instr(ctx, jalr, link, reg);
544 }
545
emit_jr(unsigned int reg,struct jit_ctx * ctx)546 static inline void emit_jr(unsigned int reg, struct jit_ctx *ctx)
547 {
548 emit_instr(ctx, jr, reg);
549 }
550
align_sp(unsigned int num)551 static inline u16 align_sp(unsigned int num)
552 {
553 /* Double word alignment for 32-bit, quadword for 64-bit */
554 unsigned int align = config_enabled(CONFIG_64BIT) ? 16 : 8;
555 num = (num + (align - 1)) & -align;
556 return num;
557 }
558
save_bpf_jit_regs(struct jit_ctx * ctx,unsigned offset)559 static void save_bpf_jit_regs(struct jit_ctx *ctx, unsigned offset)
560 {
561 int i = 0, real_off = 0;
562 u32 sflags, tmp_flags;
563
564 /* Adjust the stack pointer */
565 emit_stack_offset(-align_sp(offset), ctx);
566
567 if (ctx->flags & SEEN_CALL) {
568 /* Argument save area */
569 if (config_enabled(CONFIG_64BIT))
570 /* Bottom of current frame */
571 real_off = align_sp(offset) - RSIZE;
572 else
573 /* Top of previous frame */
574 real_off = align_sp(offset) + RSIZE;
575 emit_store_stack_reg(MIPS_R_A0, r_sp, real_off, ctx);
576 emit_store_stack_reg(MIPS_R_A1, r_sp, real_off + RSIZE, ctx);
577
578 real_off = 0;
579 }
580
581 tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT;
582 /* sflags is essentially a bitmap */
583 while (tmp_flags) {
584 if ((sflags >> i) & 0x1) {
585 emit_store_stack_reg(MIPS_R_S0 + i, r_sp, real_off,
586 ctx);
587 real_off += RSIZE;
588 }
589 i++;
590 tmp_flags >>= 1;
591 }
592
593 /* save return address */
594 if (ctx->flags & SEEN_CALL) {
595 emit_store_stack_reg(r_ra, r_sp, real_off, ctx);
596 real_off += RSIZE;
597 }
598
599 /* Setup r_M leaving the alignment gap if necessary */
600 if (ctx->flags & SEEN_MEM) {
601 if (real_off % (RSIZE * 2))
602 real_off += RSIZE;
603 emit_long_instr(ctx, ADDIU, r_M, r_sp, real_off);
604 }
605 }
606
restore_bpf_jit_regs(struct jit_ctx * ctx,unsigned int offset)607 static void restore_bpf_jit_regs(struct jit_ctx *ctx,
608 unsigned int offset)
609 {
610 int i, real_off = 0;
611 u32 sflags, tmp_flags;
612
613 if (ctx->flags & SEEN_CALL) {
614 if (config_enabled(CONFIG_64BIT))
615 /* Bottom of current frame */
616 real_off = align_sp(offset) - RSIZE;
617 else
618 /* Top of previous frame */
619 real_off = align_sp(offset) + RSIZE;
620 emit_load_stack_reg(MIPS_R_A0, r_sp, real_off, ctx);
621 emit_load_stack_reg(MIPS_R_A1, r_sp, real_off + RSIZE, ctx);
622
623 real_off = 0;
624 }
625
626 tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT;
627 /* sflags is a bitmap */
628 i = 0;
629 while (tmp_flags) {
630 if ((sflags >> i) & 0x1) {
631 emit_load_stack_reg(MIPS_R_S0 + i, r_sp, real_off,
632 ctx);
633 real_off += RSIZE;
634 }
635 i++;
636 tmp_flags >>= 1;
637 }
638
639 /* restore return address */
640 if (ctx->flags & SEEN_CALL)
641 emit_load_stack_reg(r_ra, r_sp, real_off, ctx);
642
643 /* Restore the sp and discard the scrach memory */
644 emit_stack_offset(align_sp(offset), ctx);
645 }
646
get_stack_depth(struct jit_ctx * ctx)647 static unsigned int get_stack_depth(struct jit_ctx *ctx)
648 {
649 int sp_off = 0;
650
651
652 /* How may s* regs do we need to preserved? */
653 sp_off += hweight32(ctx->flags >> SEEN_SREG_SFT) * RSIZE;
654
655 if (ctx->flags & SEEN_MEM)
656 sp_off += 4 * BPF_MEMWORDS; /* BPF_MEMWORDS are 32-bit */
657
658 if (ctx->flags & SEEN_CALL)
659 /*
660 * The JIT code make calls to external functions using 2
661 * arguments. Therefore, for o32 we don't need to allocate
662 * space because we don't care if the argumetns are lost
663 * across calls. We do need however to preserve incoming
664 * arguments but the space is already allocated for us by
665 * the caller. On the other hand, for n64, we need to allocate
666 * this space ourselves. We need to preserve $ra as well.
667 */
668 sp_off += config_enabled(CONFIG_64BIT) ?
669 (ARGS_USED_BY_JIT + 1) * RSIZE : RSIZE;
670
671 return sp_off;
672 }
673
build_prologue(struct jit_ctx * ctx)674 static void build_prologue(struct jit_ctx *ctx)
675 {
676 int sp_off;
677
678 /* Calculate the total offset for the stack pointer */
679 sp_off = get_stack_depth(ctx);
680 save_bpf_jit_regs(ctx, sp_off);
681
682 if (ctx->flags & SEEN_SKB)
683 emit_reg_move(r_skb, MIPS_R_A0, ctx);
684
685 if (ctx->flags & SEEN_X)
686 emit_jit_reg_move(r_X, r_zero, ctx);
687
688 /* Do not leak kernel data to userspace */
689 if (bpf_needs_clear_a(&ctx->skf->insns[0]))
690 emit_jit_reg_move(r_A, r_zero, ctx);
691 }
692
build_epilogue(struct jit_ctx * ctx)693 static void build_epilogue(struct jit_ctx *ctx)
694 {
695 unsigned int sp_off;
696
697 /* Calculate the total offset for the stack pointer */
698
699 sp_off = get_stack_depth(ctx);
700 restore_bpf_jit_regs(ctx, sp_off);
701
702 /* Return */
703 emit_jr(r_ra, ctx);
704 emit_nop(ctx);
705 }
706
jit_get_skb_b(struct sk_buff * skb,unsigned offset)707 static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset)
708 {
709 u8 ret;
710 int err;
711
712 err = skb_copy_bits(skb, offset, &ret, 1);
713
714 return (u64)err << 32 | ret;
715 }
716
jit_get_skb_h(struct sk_buff * skb,unsigned offset)717 static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset)
718 {
719 u16 ret;
720 int err;
721
722 err = skb_copy_bits(skb, offset, &ret, 2);
723
724 return (u64)err << 32 | ntohs(ret);
725 }
726
jit_get_skb_w(struct sk_buff * skb,unsigned offset)727 static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
728 {
729 u32 ret;
730 int err;
731
732 err = skb_copy_bits(skb, offset, &ret, 4);
733
734 return (u64)err << 32 | ntohl(ret);
735 }
736
build_body(struct jit_ctx * ctx)737 static int build_body(struct jit_ctx *ctx)
738 {
739 void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w};
740 const struct bpf_prog *prog = ctx->skf;
741 const struct sock_filter *inst;
742 unsigned int i, off, load_order, condt;
743 u32 k, b_off __maybe_unused;
744
745 for (i = 0; i < prog->len; i++) {
746 u16 code;
747
748 inst = &(prog->insns[i]);
749 pr_debug("%s: code->0x%02x, jt->0x%x, jf->0x%x, k->0x%x\n",
750 __func__, inst->code, inst->jt, inst->jf, inst->k);
751 k = inst->k;
752 code = bpf_anc_helper(inst);
753
754 if (ctx->target == NULL)
755 ctx->offsets[i] = ctx->idx * 4;
756
757 switch (code) {
758 case BPF_LD | BPF_IMM:
759 /* A <- k ==> li r_A, k */
760 ctx->flags |= SEEN_A;
761 emit_load_imm(r_A, k, ctx);
762 break;
763 case BPF_LD | BPF_W | BPF_LEN:
764 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
765 /* A <- len ==> lw r_A, offset(skb) */
766 ctx->flags |= SEEN_SKB | SEEN_A;
767 off = offsetof(struct sk_buff, len);
768 emit_load(r_A, r_skb, off, ctx);
769 break;
770 case BPF_LD | BPF_MEM:
771 /* A <- M[k] ==> lw r_A, offset(M) */
772 ctx->flags |= SEEN_MEM | SEEN_A;
773 emit_load(r_A, r_M, SCRATCH_OFF(k), ctx);
774 break;
775 case BPF_LD | BPF_W | BPF_ABS:
776 /* A <- P[k:4] */
777 load_order = 2;
778 goto load;
779 case BPF_LD | BPF_H | BPF_ABS:
780 /* A <- P[k:2] */
781 load_order = 1;
782 goto load;
783 case BPF_LD | BPF_B | BPF_ABS:
784 /* A <- P[k:1] */
785 load_order = 0;
786 load:
787 /* the interpreter will deal with the negative K */
788 if ((int)k < 0)
789 return -ENOTSUPP;
790
791 emit_load_imm(r_off, k, ctx);
792 load_common:
793 /*
794 * We may got here from the indirect loads so
795 * return if offset is negative.
796 */
797 emit_slt(r_s0, r_off, r_zero, ctx);
798 emit_bcond(MIPS_COND_NE, r_s0, r_zero,
799 b_imm(prog->len, ctx), ctx);
800 emit_reg_move(r_ret, r_zero, ctx);
801
802 ctx->flags |= SEEN_CALL | SEEN_OFF | SEEN_S0 |
803 SEEN_SKB | SEEN_A;
804
805 emit_load_func(r_s0, (ptr)load_func[load_order],
806 ctx);
807 emit_reg_move(MIPS_R_A0, r_skb, ctx);
808 emit_jalr(MIPS_R_RA, r_s0, ctx);
809 /* Load second argument to delay slot */
810 emit_reg_move(MIPS_R_A1, r_off, ctx);
811 /* Check the error value */
812 if (config_enabled(CONFIG_64BIT)) {
813 /* Get error code from the top 32-bits */
814 emit_dsrl32(r_s0, r_val, 0, ctx);
815 /* Branch to 3 instructions ahead */
816 emit_bcond(MIPS_COND_NE, r_s0, r_zero, 3 << 2,
817 ctx);
818 } else {
819 /* Branch to 3 instructions ahead */
820 emit_bcond(MIPS_COND_NE, r_err, r_zero, 3 << 2,
821 ctx);
822 }
823 emit_nop(ctx);
824 /* We are good */
825 emit_b(b_imm(i + 1, ctx), ctx);
826 emit_jit_reg_move(r_A, r_val, ctx);
827 /* Return with error */
828 emit_b(b_imm(prog->len, ctx), ctx);
829 emit_reg_move(r_ret, r_zero, ctx);
830 break;
831 case BPF_LD | BPF_W | BPF_IND:
832 /* A <- P[X + k:4] */
833 load_order = 2;
834 goto load_ind;
835 case BPF_LD | BPF_H | BPF_IND:
836 /* A <- P[X + k:2] */
837 load_order = 1;
838 goto load_ind;
839 case BPF_LD | BPF_B | BPF_IND:
840 /* A <- P[X + k:1] */
841 load_order = 0;
842 load_ind:
843 ctx->flags |= SEEN_OFF | SEEN_X;
844 emit_addiu(r_off, r_X, k, ctx);
845 goto load_common;
846 case BPF_LDX | BPF_IMM:
847 /* X <- k */
848 ctx->flags |= SEEN_X;
849 emit_load_imm(r_X, k, ctx);
850 break;
851 case BPF_LDX | BPF_MEM:
852 /* X <- M[k] */
853 ctx->flags |= SEEN_X | SEEN_MEM;
854 emit_load(r_X, r_M, SCRATCH_OFF(k), ctx);
855 break;
856 case BPF_LDX | BPF_W | BPF_LEN:
857 /* X <- len */
858 ctx->flags |= SEEN_X | SEEN_SKB;
859 off = offsetof(struct sk_buff, len);
860 emit_load(r_X, r_skb, off, ctx);
861 break;
862 case BPF_LDX | BPF_B | BPF_MSH:
863 /* the interpreter will deal with the negative K */
864 if ((int)k < 0)
865 return -ENOTSUPP;
866
867 /* X <- 4 * (P[k:1] & 0xf) */
868 ctx->flags |= SEEN_X | SEEN_CALL | SEEN_S0 | SEEN_SKB;
869 /* Load offset to a1 */
870 emit_load_func(r_s0, (ptr)jit_get_skb_b, ctx);
871 /*
872 * This may emit two instructions so it may not fit
873 * in the delay slot. So use a0 in the delay slot.
874 */
875 emit_load_imm(MIPS_R_A1, k, ctx);
876 emit_jalr(MIPS_R_RA, r_s0, ctx);
877 emit_reg_move(MIPS_R_A0, r_skb, ctx); /* delay slot */
878 /* Check the error value */
879 if (config_enabled(CONFIG_64BIT)) {
880 /* Top 32-bits of $v0 on 64-bit */
881 emit_dsrl32(r_s0, r_val, 0, ctx);
882 emit_bcond(MIPS_COND_NE, r_s0, r_zero,
883 3 << 2, ctx);
884 } else {
885 emit_bcond(MIPS_COND_NE, r_err, r_zero,
886 3 << 2, ctx);
887 }
888 /* No need for delay slot */
889 /* We are good */
890 /* X <- P[1:K] & 0xf */
891 emit_andi(r_X, r_val, 0xf, ctx);
892 /* X << 2 */
893 emit_b(b_imm(i + 1, ctx), ctx);
894 emit_sll(r_X, r_X, 2, ctx); /* delay slot */
895 /* Return with error */
896 emit_b(b_imm(prog->len, ctx), ctx);
897 emit_load_imm(r_ret, 0, ctx); /* delay slot */
898 break;
899 case BPF_ST:
900 /* M[k] <- A */
901 ctx->flags |= SEEN_MEM | SEEN_A;
902 emit_store(r_A, r_M, SCRATCH_OFF(k), ctx);
903 break;
904 case BPF_STX:
905 /* M[k] <- X */
906 ctx->flags |= SEEN_MEM | SEEN_X;
907 emit_store(r_X, r_M, SCRATCH_OFF(k), ctx);
908 break;
909 case BPF_ALU | BPF_ADD | BPF_K:
910 /* A += K */
911 ctx->flags |= SEEN_A;
912 emit_addiu(r_A, r_A, k, ctx);
913 break;
914 case BPF_ALU | BPF_ADD | BPF_X:
915 /* A += X */
916 ctx->flags |= SEEN_A | SEEN_X;
917 emit_addu(r_A, r_A, r_X, ctx);
918 break;
919 case BPF_ALU | BPF_SUB | BPF_K:
920 /* A -= K */
921 ctx->flags |= SEEN_A;
922 emit_addiu(r_A, r_A, -k, ctx);
923 break;
924 case BPF_ALU | BPF_SUB | BPF_X:
925 /* A -= X */
926 ctx->flags |= SEEN_A | SEEN_X;
927 emit_subu(r_A, r_A, r_X, ctx);
928 break;
929 case BPF_ALU | BPF_MUL | BPF_K:
930 /* A *= K */
931 /* Load K to scratch register before MUL */
932 ctx->flags |= SEEN_A | SEEN_S0;
933 emit_load_imm(r_s0, k, ctx);
934 emit_mul(r_A, r_A, r_s0, ctx);
935 break;
936 case BPF_ALU | BPF_MUL | BPF_X:
937 /* A *= X */
938 ctx->flags |= SEEN_A | SEEN_X;
939 emit_mul(r_A, r_A, r_X, ctx);
940 break;
941 case BPF_ALU | BPF_DIV | BPF_K:
942 /* A /= k */
943 if (k == 1)
944 break;
945 if (optimize_div(&k)) {
946 ctx->flags |= SEEN_A;
947 emit_srl(r_A, r_A, k, ctx);
948 break;
949 }
950 ctx->flags |= SEEN_A | SEEN_S0;
951 emit_load_imm(r_s0, k, ctx);
952 emit_div(r_A, r_s0, ctx);
953 break;
954 case BPF_ALU | BPF_MOD | BPF_K:
955 /* A %= k */
956 if (k == 1) {
957 ctx->flags |= SEEN_A;
958 emit_jit_reg_move(r_A, r_zero, ctx);
959 } else {
960 ctx->flags |= SEEN_A | SEEN_S0;
961 emit_load_imm(r_s0, k, ctx);
962 emit_mod(r_A, r_s0, ctx);
963 }
964 break;
965 case BPF_ALU | BPF_DIV | BPF_X:
966 /* A /= X */
967 ctx->flags |= SEEN_X | SEEN_A;
968 /* Check if r_X is zero */
969 emit_bcond(MIPS_COND_EQ, r_X, r_zero,
970 b_imm(prog->len, ctx), ctx);
971 emit_load_imm(r_val, 0, ctx); /* delay slot */
972 emit_div(r_A, r_X, ctx);
973 break;
974 case BPF_ALU | BPF_MOD | BPF_X:
975 /* A %= X */
976 ctx->flags |= SEEN_X | SEEN_A;
977 /* Check if r_X is zero */
978 emit_bcond(MIPS_COND_EQ, r_X, r_zero,
979 b_imm(prog->len, ctx), ctx);
980 emit_load_imm(r_val, 0, ctx); /* delay slot */
981 emit_mod(r_A, r_X, ctx);
982 break;
983 case BPF_ALU | BPF_OR | BPF_K:
984 /* A |= K */
985 ctx->flags |= SEEN_A;
986 emit_ori(r_A, r_A, k, ctx);
987 break;
988 case BPF_ALU | BPF_OR | BPF_X:
989 /* A |= X */
990 ctx->flags |= SEEN_A;
991 emit_ori(r_A, r_A, r_X, ctx);
992 break;
993 case BPF_ALU | BPF_XOR | BPF_K:
994 /* A ^= k */
995 ctx->flags |= SEEN_A;
996 emit_xori(r_A, r_A, k, ctx);
997 break;
998 case BPF_ANC | SKF_AD_ALU_XOR_X:
999 case BPF_ALU | BPF_XOR | BPF_X:
1000 /* A ^= X */
1001 ctx->flags |= SEEN_A;
1002 emit_xor(r_A, r_A, r_X, ctx);
1003 break;
1004 case BPF_ALU | BPF_AND | BPF_K:
1005 /* A &= K */
1006 ctx->flags |= SEEN_A;
1007 emit_andi(r_A, r_A, k, ctx);
1008 break;
1009 case BPF_ALU | BPF_AND | BPF_X:
1010 /* A &= X */
1011 ctx->flags |= SEEN_A | SEEN_X;
1012 emit_and(r_A, r_A, r_X, ctx);
1013 break;
1014 case BPF_ALU | BPF_LSH | BPF_K:
1015 /* A <<= K */
1016 ctx->flags |= SEEN_A;
1017 emit_sll(r_A, r_A, k, ctx);
1018 break;
1019 case BPF_ALU | BPF_LSH | BPF_X:
1020 /* A <<= X */
1021 ctx->flags |= SEEN_A | SEEN_X;
1022 emit_sllv(r_A, r_A, r_X, ctx);
1023 break;
1024 case BPF_ALU | BPF_RSH | BPF_K:
1025 /* A >>= K */
1026 ctx->flags |= SEEN_A;
1027 emit_srl(r_A, r_A, k, ctx);
1028 break;
1029 case BPF_ALU | BPF_RSH | BPF_X:
1030 ctx->flags |= SEEN_A | SEEN_X;
1031 emit_srlv(r_A, r_A, r_X, ctx);
1032 break;
1033 case BPF_ALU | BPF_NEG:
1034 /* A = -A */
1035 ctx->flags |= SEEN_A;
1036 emit_neg(r_A, ctx);
1037 break;
1038 case BPF_JMP | BPF_JA:
1039 /* pc += K */
1040 emit_b(b_imm(i + k + 1, ctx), ctx);
1041 emit_nop(ctx);
1042 break;
1043 case BPF_JMP | BPF_JEQ | BPF_K:
1044 /* pc += ( A == K ) ? pc->jt : pc->jf */
1045 condt = MIPS_COND_EQ | MIPS_COND_K;
1046 goto jmp_cmp;
1047 case BPF_JMP | BPF_JEQ | BPF_X:
1048 ctx->flags |= SEEN_X;
1049 /* pc += ( A == X ) ? pc->jt : pc->jf */
1050 condt = MIPS_COND_EQ | MIPS_COND_X;
1051 goto jmp_cmp;
1052 case BPF_JMP | BPF_JGE | BPF_K:
1053 /* pc += ( A >= K ) ? pc->jt : pc->jf */
1054 condt = MIPS_COND_GE | MIPS_COND_K;
1055 goto jmp_cmp;
1056 case BPF_JMP | BPF_JGE | BPF_X:
1057 ctx->flags |= SEEN_X;
1058 /* pc += ( A >= X ) ? pc->jt : pc->jf */
1059 condt = MIPS_COND_GE | MIPS_COND_X;
1060 goto jmp_cmp;
1061 case BPF_JMP | BPF_JGT | BPF_K:
1062 /* pc += ( A > K ) ? pc->jt : pc->jf */
1063 condt = MIPS_COND_GT | MIPS_COND_K;
1064 goto jmp_cmp;
1065 case BPF_JMP | BPF_JGT | BPF_X:
1066 ctx->flags |= SEEN_X;
1067 /* pc += ( A > X ) ? pc->jt : pc->jf */
1068 condt = MIPS_COND_GT | MIPS_COND_X;
1069 jmp_cmp:
1070 /* Greater or Equal */
1071 if ((condt & MIPS_COND_GE) ||
1072 (condt & MIPS_COND_GT)) {
1073 if (condt & MIPS_COND_K) { /* K */
1074 ctx->flags |= SEEN_S0 | SEEN_A;
1075 emit_sltiu(r_s0, r_A, k, ctx);
1076 } else { /* X */
1077 ctx->flags |= SEEN_S0 | SEEN_A |
1078 SEEN_X;
1079 emit_sltu(r_s0, r_A, r_X, ctx);
1080 }
1081 /* A < (K|X) ? r_scrach = 1 */
1082 b_off = b_imm(i + inst->jf + 1, ctx);
1083 emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off,
1084 ctx);
1085 emit_nop(ctx);
1086 /* A > (K|X) ? scratch = 0 */
1087 if (condt & MIPS_COND_GT) {
1088 /* Checking for equality */
1089 ctx->flags |= SEEN_S0 | SEEN_A | SEEN_X;
1090 if (condt & MIPS_COND_K)
1091 emit_load_imm(r_s0, k, ctx);
1092 else
1093 emit_jit_reg_move(r_s0, r_X,
1094 ctx);
1095 b_off = b_imm(i + inst->jf + 1, ctx);
1096 emit_bcond(MIPS_COND_EQ, r_A, r_s0,
1097 b_off, ctx);
1098 emit_nop(ctx);
1099 /* Finally, A > K|X */
1100 b_off = b_imm(i + inst->jt + 1, ctx);
1101 emit_b(b_off, ctx);
1102 emit_nop(ctx);
1103 } else {
1104 /* A >= (K|X) so jump */
1105 b_off = b_imm(i + inst->jt + 1, ctx);
1106 emit_b(b_off, ctx);
1107 emit_nop(ctx);
1108 }
1109 } else {
1110 /* A == K|X */
1111 if (condt & MIPS_COND_K) { /* K */
1112 ctx->flags |= SEEN_S0 | SEEN_A;
1113 emit_load_imm(r_s0, k, ctx);
1114 /* jump true */
1115 b_off = b_imm(i + inst->jt + 1, ctx);
1116 emit_bcond(MIPS_COND_EQ, r_A, r_s0,
1117 b_off, ctx);
1118 emit_nop(ctx);
1119 /* jump false */
1120 b_off = b_imm(i + inst->jf + 1,
1121 ctx);
1122 emit_bcond(MIPS_COND_NE, r_A, r_s0,
1123 b_off, ctx);
1124 emit_nop(ctx);
1125 } else { /* X */
1126 /* jump true */
1127 ctx->flags |= SEEN_A | SEEN_X;
1128 b_off = b_imm(i + inst->jt + 1,
1129 ctx);
1130 emit_bcond(MIPS_COND_EQ, r_A, r_X,
1131 b_off, ctx);
1132 emit_nop(ctx);
1133 /* jump false */
1134 b_off = b_imm(i + inst->jf + 1, ctx);
1135 emit_bcond(MIPS_COND_NE, r_A, r_X,
1136 b_off, ctx);
1137 emit_nop(ctx);
1138 }
1139 }
1140 break;
1141 case BPF_JMP | BPF_JSET | BPF_K:
1142 ctx->flags |= SEEN_S0 | SEEN_S1 | SEEN_A;
1143 /* pc += (A & K) ? pc -> jt : pc -> jf */
1144 emit_load_imm(r_s1, k, ctx);
1145 emit_and(r_s0, r_A, r_s1, ctx);
1146 /* jump true */
1147 b_off = b_imm(i + inst->jt + 1, ctx);
1148 emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx);
1149 emit_nop(ctx);
1150 /* jump false */
1151 b_off = b_imm(i + inst->jf + 1, ctx);
1152 emit_b(b_off, ctx);
1153 emit_nop(ctx);
1154 break;
1155 case BPF_JMP | BPF_JSET | BPF_X:
1156 ctx->flags |= SEEN_S0 | SEEN_X | SEEN_A;
1157 /* pc += (A & X) ? pc -> jt : pc -> jf */
1158 emit_and(r_s0, r_A, r_X, ctx);
1159 /* jump true */
1160 b_off = b_imm(i + inst->jt + 1, ctx);
1161 emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx);
1162 emit_nop(ctx);
1163 /* jump false */
1164 b_off = b_imm(i + inst->jf + 1, ctx);
1165 emit_b(b_off, ctx);
1166 emit_nop(ctx);
1167 break;
1168 case BPF_RET | BPF_A:
1169 ctx->flags |= SEEN_A;
1170 if (i != prog->len - 1)
1171 /*
1172 * If this is not the last instruction
1173 * then jump to the epilogue
1174 */
1175 emit_b(b_imm(prog->len, ctx), ctx);
1176 emit_reg_move(r_ret, r_A, ctx); /* delay slot */
1177 break;
1178 case BPF_RET | BPF_K:
1179 /*
1180 * It can emit two instructions so it does not fit on
1181 * the delay slot.
1182 */
1183 emit_load_imm(r_ret, k, ctx);
1184 if (i != prog->len - 1) {
1185 /*
1186 * If this is not the last instruction
1187 * then jump to the epilogue
1188 */
1189 emit_b(b_imm(prog->len, ctx), ctx);
1190 emit_nop(ctx);
1191 }
1192 break;
1193 case BPF_MISC | BPF_TAX:
1194 /* X = A */
1195 ctx->flags |= SEEN_X | SEEN_A;
1196 emit_jit_reg_move(r_X, r_A, ctx);
1197 break;
1198 case BPF_MISC | BPF_TXA:
1199 /* A = X */
1200 ctx->flags |= SEEN_A | SEEN_X;
1201 emit_jit_reg_move(r_A, r_X, ctx);
1202 break;
1203 /* AUX */
1204 case BPF_ANC | SKF_AD_PROTOCOL:
1205 /* A = ntohs(skb->protocol */
1206 ctx->flags |= SEEN_SKB | SEEN_OFF | SEEN_A;
1207 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
1208 protocol) != 2);
1209 off = offsetof(struct sk_buff, protocol);
1210 emit_half_load(r_A, r_skb, off, ctx);
1211 #ifdef CONFIG_CPU_LITTLE_ENDIAN
1212 /* This needs little endian fixup */
1213 if (cpu_has_wsbh) {
1214 /* R2 and later have the wsbh instruction */
1215 emit_wsbh(r_A, r_A, ctx);
1216 } else {
1217 /* Get first byte */
1218 emit_andi(r_tmp_imm, r_A, 0xff, ctx);
1219 /* Shift it */
1220 emit_sll(r_tmp, r_tmp_imm, 8, ctx);
1221 /* Get second byte */
1222 emit_srl(r_tmp_imm, r_A, 8, ctx);
1223 emit_andi(r_tmp_imm, r_tmp_imm, 0xff, ctx);
1224 /* Put everyting together in r_A */
1225 emit_or(r_A, r_tmp, r_tmp_imm, ctx);
1226 }
1227 #endif
1228 break;
1229 case BPF_ANC | SKF_AD_CPU:
1230 ctx->flags |= SEEN_A | SEEN_OFF;
1231 /* A = current_thread_info()->cpu */
1232 BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info,
1233 cpu) != 4);
1234 off = offsetof(struct thread_info, cpu);
1235 /* $28/gp points to the thread_info struct */
1236 emit_load(r_A, 28, off, ctx);
1237 break;
1238 case BPF_ANC | SKF_AD_IFINDEX:
1239 /* A = skb->dev->ifindex */
1240 ctx->flags |= SEEN_SKB | SEEN_A | SEEN_S0;
1241 off = offsetof(struct sk_buff, dev);
1242 /* Load *dev pointer */
1243 emit_load_ptr(r_s0, r_skb, off, ctx);
1244 /* error (0) in the delay slot */
1245 emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
1246 b_imm(prog->len, ctx), ctx);
1247 emit_reg_move(r_ret, r_zero, ctx);
1248 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
1249 ifindex) != 4);
1250 off = offsetof(struct net_device, ifindex);
1251 emit_load(r_A, r_s0, off, ctx);
1252 break;
1253 case BPF_ANC | SKF_AD_MARK:
1254 ctx->flags |= SEEN_SKB | SEEN_A;
1255 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
1256 off = offsetof(struct sk_buff, mark);
1257 emit_load(r_A, r_skb, off, ctx);
1258 break;
1259 case BPF_ANC | SKF_AD_RXHASH:
1260 ctx->flags |= SEEN_SKB | SEEN_A;
1261 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
1262 off = offsetof(struct sk_buff, hash);
1263 emit_load(r_A, r_skb, off, ctx);
1264 break;
1265 case BPF_ANC | SKF_AD_VLAN_TAG:
1266 case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
1267 ctx->flags |= SEEN_SKB | SEEN_S0 | SEEN_A;
1268 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
1269 vlan_tci) != 2);
1270 off = offsetof(struct sk_buff, vlan_tci);
1271 emit_half_load(r_s0, r_skb, off, ctx);
1272 if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
1273 emit_andi(r_A, r_s0, (u16)~VLAN_TAG_PRESENT, ctx);
1274 } else {
1275 emit_andi(r_A, r_s0, VLAN_TAG_PRESENT, ctx);
1276 /* return 1 if present */
1277 emit_sltu(r_A, r_zero, r_A, ctx);
1278 }
1279 break;
1280 case BPF_ANC | SKF_AD_PKTTYPE:
1281 ctx->flags |= SEEN_SKB;
1282
1283 emit_load_byte(r_tmp, r_skb, PKT_TYPE_OFFSET(), ctx);
1284 /* Keep only the last 3 bits */
1285 emit_andi(r_A, r_tmp, PKT_TYPE_MAX, ctx);
1286 #ifdef __BIG_ENDIAN_BITFIELD
1287 /* Get the actual packet type to the lower 3 bits */
1288 emit_srl(r_A, r_A, 5, ctx);
1289 #endif
1290 break;
1291 case BPF_ANC | SKF_AD_QUEUE:
1292 ctx->flags |= SEEN_SKB | SEEN_A;
1293 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
1294 queue_mapping) != 2);
1295 BUILD_BUG_ON(offsetof(struct sk_buff,
1296 queue_mapping) > 0xff);
1297 off = offsetof(struct sk_buff, queue_mapping);
1298 emit_half_load(r_A, r_skb, off, ctx);
1299 break;
1300 default:
1301 pr_debug("%s: Unhandled opcode: 0x%02x\n", __FILE__,
1302 inst->code);
1303 return -1;
1304 }
1305 }
1306
1307 /* compute offsets only during the first pass */
1308 if (ctx->target == NULL)
1309 ctx->offsets[i] = ctx->idx * 4;
1310
1311 return 0;
1312 }
1313
1314 int bpf_jit_enable __read_mostly;
1315
bpf_jit_compile(struct bpf_prog * fp)1316 void bpf_jit_compile(struct bpf_prog *fp)
1317 {
1318 struct jit_ctx ctx;
1319 unsigned int alloc_size, tmp_idx;
1320
1321 if (!bpf_jit_enable)
1322 return;
1323
1324 memset(&ctx, 0, sizeof(ctx));
1325
1326 ctx.offsets = kcalloc(fp->len, sizeof(*ctx.offsets), GFP_KERNEL);
1327 if (ctx.offsets == NULL)
1328 return;
1329
1330 ctx.skf = fp;
1331
1332 if (build_body(&ctx))
1333 goto out;
1334
1335 tmp_idx = ctx.idx;
1336 build_prologue(&ctx);
1337 ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4;
1338 /* just to complete the ctx.idx count */
1339 build_epilogue(&ctx);
1340
1341 alloc_size = 4 * ctx.idx;
1342 ctx.target = module_alloc(alloc_size);
1343 if (ctx.target == NULL)
1344 goto out;
1345
1346 /* Clean it */
1347 memset(ctx.target, 0, alloc_size);
1348
1349 ctx.idx = 0;
1350
1351 /* Generate the actual JIT code */
1352 build_prologue(&ctx);
1353 build_body(&ctx);
1354 build_epilogue(&ctx);
1355
1356 /* Update the icache */
1357 flush_icache_range((ptr)ctx.target, (ptr)(ctx.target + ctx.idx));
1358
1359 if (bpf_jit_enable > 1)
1360 /* Dump JIT code */
1361 bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
1362
1363 fp->bpf_func = (void *)ctx.target;
1364 fp->jited = true;
1365
1366 out:
1367 kfree(ctx.offsets);
1368 }
1369
bpf_jit_free(struct bpf_prog * fp)1370 void bpf_jit_free(struct bpf_prog *fp)
1371 {
1372 if (fp->jited)
1373 module_memfree(fp->bpf_func);
1374
1375 bpf_prog_unlock_free(fp);
1376 }
1377