~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/mips/net/bpf_jit.c

Version: ~ [ linux-5.14-rc1 ] ~ [ linux-5.13.1 ] ~ [ linux-5.12.16 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.49 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.131 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.197 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.239 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.275 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.275 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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/asm.h>
 24 #include <asm/bitops.h>
 25 #include <asm/cacheflush.h>
 26 #include <asm/cpu-features.h>
 27 #include <asm/uasm.h>
 28 
 29 #include "bpf_jit.h"
 30 
 31 /* ABI
 32  * r_skb_hl     SKB header length
 33  * r_data       SKB data pointer
 34  * r_off        Offset
 35  * r_A          BPF register A
 36  * r_X          BPF register X
 37  * r_skb        *skb
 38  * r_M          *scratch memory
 39  * r_skb_len    SKB length
 40  *
 41  * On entry (*bpf_func)(*skb, *filter)
 42  * a0 = MIPS_R_A0 = skb;
 43  * a1 = MIPS_R_A1 = filter;
 44  *
 45  * Stack
 46  * ...
 47  * M[15]
 48  * M[14]
 49  * M[13]
 50  * ...
 51  * M[0] <-- r_M
 52  * saved reg k-1
 53  * saved reg k-2
 54  * ...
 55  * saved reg 0 <-- r_sp
 56  * <no argument area>
 57  *
 58  *                     Packet layout
 59  *
 60  * <--------------------- len ------------------------>
 61  * <--skb-len(r_skb_hl)-->< ----- skb->data_len ------>
 62  * ----------------------------------------------------
 63  * |                  skb->data                       |
 64  * ----------------------------------------------------
 65  */
 66 
 67 #define ptr typeof(unsigned long)
 68 
 69 #define SCRATCH_OFF(k)          (4 * (k))
 70 
 71 /* JIT flags */
 72 #define SEEN_CALL               (1 << BPF_MEMWORDS)
 73 #define SEEN_SREG_SFT           (BPF_MEMWORDS + 1)
 74 #define SEEN_SREG_BASE          (1 << SEEN_SREG_SFT)
 75 #define SEEN_SREG(x)            (SEEN_SREG_BASE << (x))
 76 #define SEEN_OFF                SEEN_SREG(2)
 77 #define SEEN_A                  SEEN_SREG(3)
 78 #define SEEN_X                  SEEN_SREG(4)
 79 #define SEEN_SKB                SEEN_SREG(5)
 80 #define SEEN_MEM                SEEN_SREG(6)
 81 /* SEEN_SK_DATA also implies skb_hl an skb_len */
 82 #define SEEN_SKB_DATA           (SEEN_SREG(7) | SEEN_SREG(1) | SEEN_SREG(0))
 83 
 84 /* Arguments used by JIT */
 85 #define ARGS_USED_BY_JIT        2 /* only applicable to 64-bit */
 86 
 87 #define SBIT(x)                 (1 << (x)) /* Signed version of BIT() */
 88 
 89 /**
 90  * struct jit_ctx - JIT context
 91  * @skf:                The sk_filter
 92  * @prologue_bytes:     Number of bytes for prologue
 93  * @idx:                Instruction index
 94  * @flags:              JIT flags
 95  * @offsets:            Instruction offsets
 96  * @target:             Memory location for the compiled filter
 97  */
 98 struct jit_ctx {
 99         const struct bpf_prog *skf;
100         unsigned int prologue_bytes;
101         u32 idx;
102         u32 flags;
103         u32 *offsets;
104         u32 *target;
105 };
106 
107 
108 static inline int optimize_div(u32 *k)
109 {
110         /* power of 2 divides can be implemented with right shift */
111         if (!(*k & (*k-1))) {
112                 *k = ilog2(*k);
113                 return 1;
114         }
115 
116         return 0;
117 }
118 
119 static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx);
120 
121 /* Simply emit the instruction if the JIT memory space has been allocated */
122 #define emit_instr(ctx, func, ...)                      \
123 do {                                                    \
124         if ((ctx)->target != NULL) {                    \
125                 u32 *p = &(ctx)->target[ctx->idx];      \
126                 uasm_i_##func(&p, ##__VA_ARGS__);       \
127         }                                               \
128         (ctx)->idx++;                                   \
129 } while (0)
130 
131 /*
132  * Similar to emit_instr but it must be used when we need to emit
133  * 32-bit or 64-bit instructions
134  */
135 #define emit_long_instr(ctx, func, ...)                 \
136 do {                                                    \
137         if ((ctx)->target != NULL) {                    \
138                 u32 *p = &(ctx)->target[ctx->idx];      \
139                 UASM_i_##func(&p, ##__VA_ARGS__);       \
140         }                                               \
141         (ctx)->idx++;                                   \
142 } while (0)
143 
144 /* Determine if immediate is within the 16-bit signed range */
145 static inline bool is_range16(s32 imm)
146 {
147         return !(imm >= SBIT(15) || imm < -SBIT(15));
148 }
149 
150 static inline void emit_addu(unsigned int dst, unsigned int src1,
151                              unsigned int src2, struct jit_ctx *ctx)
152 {
153         emit_instr(ctx, addu, dst, src1, src2);
154 }
155 
156 static inline void emit_nop(struct jit_ctx *ctx)
157 {
158         emit_instr(ctx, nop);
159 }
160 
161 /* Load a u32 immediate to a register */
162 static inline void emit_load_imm(unsigned int dst, u32 imm, struct jit_ctx *ctx)
163 {
164         if (ctx->target != NULL) {
165                 /* addiu can only handle s16 */
166                 if (!is_range16(imm)) {
167                         u32 *p = &ctx->target[ctx->idx];
168                         uasm_i_lui(&p, r_tmp_imm, (s32)imm >> 16);
169                         p = &ctx->target[ctx->idx + 1];
170                         uasm_i_ori(&p, dst, r_tmp_imm, imm & 0xffff);
171                 } else {
172                         u32 *p = &ctx->target[ctx->idx];
173                         uasm_i_addiu(&p, dst, r_zero, imm);
174                 }
175         }
176         ctx->idx++;
177 
178         if (!is_range16(imm))
179                 ctx->idx++;
180 }
181 
182 static inline void emit_or(unsigned int dst, unsigned int src1,
183                            unsigned int src2, struct jit_ctx *ctx)
184 {
185         emit_instr(ctx, or, dst, src1, src2);
186 }
187 
188 static inline void emit_ori(unsigned int dst, unsigned src, u32 imm,
189                             struct jit_ctx *ctx)
190 {
191         if (imm >= BIT(16)) {
192                 emit_load_imm(r_tmp, imm, ctx);
193                 emit_or(dst, src, r_tmp, ctx);
194         } else {
195                 emit_instr(ctx, ori, dst, src, imm);
196         }
197 }
198 
199 static inline void emit_daddiu(unsigned int dst, unsigned int src,
200                                int imm, struct jit_ctx *ctx)
201 {
202         /*
203          * Only used for stack, so the imm is relatively small
204          * and it fits in 15-bits
205          */
206         emit_instr(ctx, daddiu, dst, src, imm);
207 }
208 
209 static inline void emit_addiu(unsigned int dst, unsigned int src,
210                               u32 imm, struct jit_ctx *ctx)
211 {
212         if (!is_range16(imm)) {
213                 emit_load_imm(r_tmp, imm, ctx);
214                 emit_addu(dst, r_tmp, src, ctx);
215         } else {
216                 emit_instr(ctx, addiu, dst, src, imm);
217         }
218 }
219 
220 static inline void emit_and(unsigned int dst, unsigned int src1,
221                             unsigned int src2, struct jit_ctx *ctx)
222 {
223         emit_instr(ctx, and, dst, src1, src2);
224 }
225 
226 static inline void emit_andi(unsigned int dst, unsigned int src,
227                              u32 imm, struct jit_ctx *ctx)
228 {
229         /* If imm does not fit in u16 then load it to register */
230         if (imm >= BIT(16)) {
231                 emit_load_imm(r_tmp, imm, ctx);
232                 emit_and(dst, src, r_tmp, ctx);
233         } else {
234                 emit_instr(ctx, andi, dst, src, imm);
235         }
236 }
237 
238 static inline void emit_xor(unsigned int dst, unsigned int src1,
239                             unsigned int src2, struct jit_ctx *ctx)
240 {
241         emit_instr(ctx, xor, dst, src1, src2);
242 }
243 
244 static inline void emit_xori(ptr dst, ptr src, u32 imm, struct jit_ctx *ctx)
245 {
246         /* If imm does not fit in u16 then load it to register */
247         if (imm >= BIT(16)) {
248                 emit_load_imm(r_tmp, imm, ctx);
249                 emit_xor(dst, src, r_tmp, ctx);
250         } else {
251                 emit_instr(ctx, xori, dst, src, imm);
252         }
253 }
254 
255 static inline void emit_stack_offset(int offset, struct jit_ctx *ctx)
256 {
257         emit_long_instr(ctx, ADDIU, r_sp, r_sp, offset);
258 }
259 
260 static inline void emit_subu(unsigned int dst, unsigned int src1,
261                              unsigned int src2, struct jit_ctx *ctx)
262 {
263         emit_instr(ctx, subu, dst, src1, src2);
264 }
265 
266 static inline void emit_neg(unsigned int reg, struct jit_ctx *ctx)
267 {
268         emit_subu(reg, r_zero, reg, ctx);
269 }
270 
271 static inline void emit_sllv(unsigned int dst, unsigned int src,
272                              unsigned int sa, struct jit_ctx *ctx)
273 {
274         emit_instr(ctx, sllv, dst, src, sa);
275 }
276 
277 static inline void emit_sll(unsigned int dst, unsigned int src,
278                             unsigned int sa, struct jit_ctx *ctx)
279 {
280         /* sa is 5-bits long */
281         if (sa >= BIT(5))
282                 /* Shifting >= 32 results in zero */
283                 emit_jit_reg_move(dst, r_zero, ctx);
284         else
285                 emit_instr(ctx, sll, dst, src, sa);
286 }
287 
288 static inline void emit_srlv(unsigned int dst, unsigned int src,
289                              unsigned int sa, struct jit_ctx *ctx)
290 {
291         emit_instr(ctx, srlv, dst, src, sa);
292 }
293 
294 static inline void emit_srl(unsigned int dst, unsigned int src,
295                             unsigned int sa, struct jit_ctx *ctx)
296 {
297         /* sa is 5-bits long */
298         if (sa >= BIT(5))
299                 /* Shifting >= 32 results in zero */
300                 emit_jit_reg_move(dst, r_zero, ctx);
301         else
302                 emit_instr(ctx, srl, dst, src, sa);
303 }
304 
305 static inline void emit_slt(unsigned int dst, unsigned int src1,
306                             unsigned int src2, struct jit_ctx *ctx)
307 {
308         emit_instr(ctx, slt, dst, src1, src2);
309 }
310 
311 static inline void emit_sltu(unsigned int dst, unsigned int src1,
312                              unsigned int src2, struct jit_ctx *ctx)
313 {
314         emit_instr(ctx, sltu, dst, src1, src2);
315 }
316 
317 static inline void emit_sltiu(unsigned dst, unsigned int src,
318                               unsigned int imm, struct jit_ctx *ctx)
319 {
320         /* 16 bit immediate */
321         if (!is_range16((s32)imm)) {
322                 emit_load_imm(r_tmp, imm, ctx);
323                 emit_sltu(dst, src, r_tmp, ctx);
324         } else {
325                 emit_instr(ctx, sltiu, dst, src, imm);
326         }
327 
328 }
329 
330 /* Store register on the stack */
331 static inline void emit_store_stack_reg(ptr reg, ptr base,
332                                         unsigned int offset,
333                                         struct jit_ctx *ctx)
334 {
335         emit_long_instr(ctx, SW, reg, offset, base);
336 }
337 
338 static inline void emit_store(ptr reg, ptr base, unsigned int offset,
339                               struct jit_ctx *ctx)
340 {
341         emit_instr(ctx, sw, reg, offset, base);
342 }
343 
344 static inline void emit_load_stack_reg(ptr reg, ptr base,
345                                        unsigned int offset,
346                                        struct jit_ctx *ctx)
347 {
348         emit_long_instr(ctx, LW, reg, offset, base);
349 }
350 
351 static inline void emit_load(unsigned int reg, unsigned int base,
352                              unsigned int offset, struct jit_ctx *ctx)
353 {
354         emit_instr(ctx, lw, reg, offset, base);
355 }
356 
357 static inline void emit_load_byte(unsigned int reg, unsigned int base,
358                                   unsigned int offset, struct jit_ctx *ctx)
359 {
360         emit_instr(ctx, lb, reg, offset, base);
361 }
362 
363 static inline void emit_half_load(unsigned int reg, unsigned int base,
364                                   unsigned int offset, struct jit_ctx *ctx)
365 {
366         emit_instr(ctx, lh, reg, offset, base);
367 }
368 
369 static inline void emit_mul(unsigned int dst, unsigned int src1,
370                             unsigned int src2, struct jit_ctx *ctx)
371 {
372         emit_instr(ctx, mul, dst, src1, src2);
373 }
374 
375 static inline void emit_div(unsigned int dst, unsigned int src,
376                             struct jit_ctx *ctx)
377 {
378         if (ctx->target != NULL) {
379                 u32 *p = &ctx->target[ctx->idx];
380                 uasm_i_divu(&p, dst, src);
381                 p = &ctx->target[ctx->idx + 1];
382                 uasm_i_mflo(&p, dst);
383         }
384         ctx->idx += 2; /* 2 insts */
385 }
386 
387 static inline void emit_mod(unsigned int dst, unsigned int src,
388                             struct jit_ctx *ctx)
389 {
390         if (ctx->target != NULL) {
391                 u32 *p = &ctx->target[ctx->idx];
392                 uasm_i_divu(&p, dst, src);
393                 p = &ctx->target[ctx->idx + 1];
394                 uasm_i_mfhi(&p, dst);
395         }
396         ctx->idx += 2; /* 2 insts */
397 }
398 
399 static inline void emit_dsll(unsigned int dst, unsigned int src,
400                              unsigned int sa, struct jit_ctx *ctx)
401 {
402         emit_instr(ctx, dsll, dst, src, sa);
403 }
404 
405 static inline void emit_dsrl32(unsigned int dst, unsigned int src,
406                                unsigned int sa, struct jit_ctx *ctx)
407 {
408         emit_instr(ctx, dsrl32, dst, src, sa);
409 }
410 
411 static inline void emit_wsbh(unsigned int dst, unsigned int src,
412                              struct jit_ctx *ctx)
413 {
414         emit_instr(ctx, wsbh, dst, src);
415 }
416 
417 /* load pointer to register */
418 static inline void emit_load_ptr(unsigned int dst, unsigned int src,
419                                      int imm, struct jit_ctx *ctx)
420 {
421         /* src contains the base addr of the 32/64-pointer */
422         emit_long_instr(ctx, LW, dst, imm, src);
423 }
424 
425 /* load a function pointer to register */
426 static inline void emit_load_func(unsigned int reg, ptr imm,
427                                   struct jit_ctx *ctx)
428 {
429         if (config_enabled(CONFIG_64BIT)) {
430                 /* At this point imm is always 64-bit */
431                 emit_load_imm(r_tmp, (u64)imm >> 32, ctx);
432                 emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */
433                 emit_ori(r_tmp, r_tmp_imm, (imm >> 16) & 0xffff, ctx);
434                 emit_dsll(r_tmp_imm, r_tmp, 16, ctx); /* left shift by 16 */
435                 emit_ori(reg, r_tmp_imm, imm & 0xffff, ctx);
436         } else {
437                 emit_load_imm(reg, imm, ctx);
438         }
439 }
440 
441 /* Move to real MIPS register */
442 static inline void emit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx)
443 {
444         emit_long_instr(ctx, ADDU, dst, src, r_zero);
445 }
446 
447 /* Move to JIT (32-bit) register */
448 static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx)
449 {
450         emit_addu(dst, src, r_zero, ctx);
451 }
452 
453 /* Compute the immediate value for PC-relative branches. */
454 static inline u32 b_imm(unsigned int tgt, struct jit_ctx *ctx)
455 {
456         if (ctx->target == NULL)
457                 return 0;
458 
459         /*
460          * We want a pc-relative branch. We only do forward branches
461          * so tgt is always after pc. tgt is the instruction offset
462          * we want to jump to.
463 
464          * Branch on MIPS:
465          * I: target_offset <- sign_extend(offset)
466          * I+1: PC += target_offset (delay slot)
467          *
468          * ctx->idx currently points to the branch instruction
469          * but the offset is added to the delay slot so we need
470          * to subtract 4.
471          */
472         return ctx->offsets[tgt] -
473                 (ctx->idx * 4 - ctx->prologue_bytes) - 4;
474 }
475 
476 static inline void emit_bcond(int cond, unsigned int reg1, unsigned int reg2,
477                              unsigned int imm, struct jit_ctx *ctx)
478 {
479         if (ctx->target != NULL) {
480                 u32 *p = &ctx->target[ctx->idx];
481 
482                 switch (cond) {
483                 case MIPS_COND_EQ:
484                         uasm_i_beq(&p, reg1, reg2, imm);
485                         break;
486                 case MIPS_COND_NE:
487                         uasm_i_bne(&p, reg1, reg2, imm);
488                         break;
489                 case MIPS_COND_ALL:
490                         uasm_i_b(&p, imm);
491                         break;
492                 default:
493                         pr_warn("%s: Unhandled branch conditional: %d\n",
494                                 __func__, cond);
495                 }
496         }
497         ctx->idx++;
498 }
499 
500 static inline void emit_b(unsigned int imm, struct jit_ctx *ctx)
501 {
502         emit_bcond(MIPS_COND_ALL, r_zero, r_zero, imm, ctx);
503 }
504 
505 static inline void emit_jalr(unsigned int link, unsigned int reg,
506                              struct jit_ctx *ctx)
507 {
508         emit_instr(ctx, jalr, link, reg);
509 }
510 
511 static inline void emit_jr(unsigned int reg, struct jit_ctx *ctx)
512 {
513         emit_instr(ctx, jr, reg);
514 }
515 
516 static inline u16 align_sp(unsigned int num)
517 {
518         /* Double word alignment for 32-bit, quadword for 64-bit */
519         unsigned int align = config_enabled(CONFIG_64BIT) ? 16 : 8;
520         num = (num + (align - 1)) & -align;
521         return num;
522 }
523 
524 static bool is_load_to_a(u16 inst)
525 {
526         switch (inst) {
527         case BPF_LD | BPF_W | BPF_LEN:
528         case BPF_LD | BPF_W | BPF_ABS:
529         case BPF_LD | BPF_H | BPF_ABS:
530         case BPF_LD | BPF_B | BPF_ABS:
531                 return true;
532         default:
533                 return false;
534         }
535 }
536 
537 static void save_bpf_jit_regs(struct jit_ctx *ctx, unsigned offset)
538 {
539         int i = 0, real_off = 0;
540         u32 sflags, tmp_flags;
541 
542         /* Adjust the stack pointer */
543         emit_stack_offset(-align_sp(offset), ctx);
544 
545         tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT;
546         /* sflags is essentially a bitmap */
547         while (tmp_flags) {
548                 if ((sflags >> i) & 0x1) {
549                         emit_store_stack_reg(MIPS_R_S0 + i, r_sp, real_off,
550                                              ctx);
551                         real_off += SZREG;
552                 }
553                 i++;
554                 tmp_flags >>= 1;
555         }
556 
557         /* save return address */
558         if (ctx->flags & SEEN_CALL) {
559                 emit_store_stack_reg(r_ra, r_sp, real_off, ctx);
560                 real_off += SZREG;
561         }
562 
563         /* Setup r_M leaving the alignment gap if necessary */
564         if (ctx->flags & SEEN_MEM) {
565                 if (real_off % (SZREG * 2))
566                         real_off += SZREG;
567                 emit_long_instr(ctx, ADDIU, r_M, r_sp, real_off);
568         }
569 }
570 
571 static void restore_bpf_jit_regs(struct jit_ctx *ctx,
572                                  unsigned int offset)
573 {
574         int i, real_off = 0;
575         u32 sflags, tmp_flags;
576 
577         tmp_flags = sflags = ctx->flags >> SEEN_SREG_SFT;
578         /* sflags is a bitmap */
579         i = 0;
580         while (tmp_flags) {
581                 if ((sflags >> i) & 0x1) {
582                         emit_load_stack_reg(MIPS_R_S0 + i, r_sp, real_off,
583                                             ctx);
584                         real_off += SZREG;
585                 }
586                 i++;
587                 tmp_flags >>= 1;
588         }
589 
590         /* restore return address */
591         if (ctx->flags & SEEN_CALL)
592                 emit_load_stack_reg(r_ra, r_sp, real_off, ctx);
593 
594         /* Restore the sp and discard the scrach memory */
595         emit_stack_offset(align_sp(offset), ctx);
596 }
597 
598 static unsigned int get_stack_depth(struct jit_ctx *ctx)
599 {
600         int sp_off = 0;
601 
602 
603         /* How may s* regs do we need to preserved? */
604         sp_off += hweight32(ctx->flags >> SEEN_SREG_SFT) * SZREG;
605 
606         if (ctx->flags & SEEN_MEM)
607                 sp_off += 4 * BPF_MEMWORDS; /* BPF_MEMWORDS are 32-bit */
608 
609         if (ctx->flags & SEEN_CALL)
610                 sp_off += SZREG; /* Space for our ra register */
611 
612         return sp_off;
613 }
614 
615 static void build_prologue(struct jit_ctx *ctx)
616 {
617         u16 first_inst = ctx->skf->insns[0].code;
618         int sp_off;
619 
620         /* Calculate the total offset for the stack pointer */
621         sp_off = get_stack_depth(ctx);
622         save_bpf_jit_regs(ctx, sp_off);
623 
624         if (ctx->flags & SEEN_SKB)
625                 emit_reg_move(r_skb, MIPS_R_A0, ctx);
626 
627         if (ctx->flags & SEEN_SKB_DATA) {
628                 /* Load packet length */
629                 emit_load(r_skb_len, r_skb, offsetof(struct sk_buff, len),
630                           ctx);
631                 emit_load(r_tmp, r_skb, offsetof(struct sk_buff, data_len),
632                           ctx);
633                 /* Load the data pointer */
634                 emit_load_ptr(r_skb_data, r_skb,
635                               offsetof(struct sk_buff, data), ctx);
636                 /* Load the header length */
637                 emit_subu(r_skb_hl, r_skb_len, r_tmp, ctx);
638         }
639 
640         if (ctx->flags & SEEN_X)
641                 emit_jit_reg_move(r_X, r_zero, ctx);
642 
643         /* Do not leak kernel data to userspace */
644         if ((first_inst != (BPF_RET | BPF_K)) && !(is_load_to_a(first_inst)))
645                 emit_jit_reg_move(r_A, r_zero, ctx);
646 }
647 
648 static void build_epilogue(struct jit_ctx *ctx)
649 {
650         unsigned int sp_off;
651 
652         /* Calculate the total offset for the stack pointer */
653 
654         sp_off = get_stack_depth(ctx);
655         restore_bpf_jit_regs(ctx, sp_off);
656 
657         /* Return */
658         emit_jr(r_ra, ctx);
659         emit_nop(ctx);
660 }
661 
662 #define CHOOSE_LOAD_FUNC(K, func) \
663         ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative : func) : \
664          func##_positive)
665 
666 static int build_body(struct jit_ctx *ctx)
667 {
668         const struct bpf_prog *prog = ctx->skf;
669         const struct sock_filter *inst;
670         unsigned int i, off, condt;
671         u32 k, b_off __maybe_unused;
672         u8 (*sk_load_func)(unsigned long *skb, int offset);
673 
674         for (i = 0; i < prog->len; i++) {
675                 u16 code;
676 
677                 inst = &(prog->insns[i]);
678                 pr_debug("%s: code->0x%02x, jt->0x%x, jf->0x%x, k->0x%x\n",
679                          __func__, inst->code, inst->jt, inst->jf, inst->k);
680                 k = inst->k;
681                 code = bpf_anc_helper(inst);
682 
683                 if (ctx->target == NULL)
684                         ctx->offsets[i] = ctx->idx * 4;
685 
686                 switch (code) {
687                 case BPF_LD | BPF_IMM:
688                         /* A <- k ==> li r_A, k */
689                         ctx->flags |= SEEN_A;
690                         emit_load_imm(r_A, k, ctx);
691                         break;
692                 case BPF_LD | BPF_W | BPF_LEN:
693                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
694                         /* A <- len ==> lw r_A, offset(skb) */
695                         ctx->flags |= SEEN_SKB | SEEN_A;
696                         off = offsetof(struct sk_buff, len);
697                         emit_load(r_A, r_skb, off, ctx);
698                         break;
699                 case BPF_LD | BPF_MEM:
700                         /* A <- M[k] ==> lw r_A, offset(M) */
701                         ctx->flags |= SEEN_MEM | SEEN_A;
702                         emit_load(r_A, r_M, SCRATCH_OFF(k), ctx);
703                         break;
704                 case BPF_LD | BPF_W | BPF_ABS:
705                         /* A <- P[k:4] */
706                         sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_word);
707                         goto load;
708                 case BPF_LD | BPF_H | BPF_ABS:
709                         /* A <- P[k:2] */
710                         sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_half);
711                         goto load;
712                 case BPF_LD | BPF_B | BPF_ABS:
713                         /* A <- P[k:1] */
714                         sk_load_func = CHOOSE_LOAD_FUNC(k, sk_load_byte);
715 load:
716                         emit_load_imm(r_off, k, ctx);
717 load_common:
718                         ctx->flags |= SEEN_CALL | SEEN_OFF |
719                                 SEEN_SKB | SEEN_A | SEEN_SKB_DATA;
720 
721                         emit_load_func(r_s0, (ptr)sk_load_func, ctx);
722                         emit_reg_move(MIPS_R_A0, r_skb, ctx);
723                         emit_jalr(MIPS_R_RA, r_s0, ctx);
724                         /* Load second argument to delay slot */
725                         emit_reg_move(MIPS_R_A1, r_off, ctx);
726                         /* Check the error value */
727                         emit_bcond(MIPS_COND_EQ, r_ret, 0, b_imm(i + 1, ctx),
728                                    ctx);
729                         /* Load return register on DS for failures */
730                         emit_reg_move(r_ret, r_zero, ctx);
731                         /* Return with error */
732                         emit_b(b_imm(prog->len, ctx), ctx);
733                         emit_nop(ctx);
734                         break;
735                 case BPF_LD | BPF_W | BPF_IND:
736                         /* A <- P[X + k:4] */
737                         sk_load_func = sk_load_word;
738                         goto load_ind;
739                 case BPF_LD | BPF_H | BPF_IND:
740                         /* A <- P[X + k:2] */
741                         sk_load_func = sk_load_half;
742                         goto load_ind;
743                 case BPF_LD | BPF_B | BPF_IND:
744                         /* A <- P[X + k:1] */
745                         sk_load_func = sk_load_byte;
746 load_ind:
747                         ctx->flags |= SEEN_OFF | SEEN_X;
748                         emit_addiu(r_off, r_X, k, ctx);
749                         goto load_common;
750                 case BPF_LDX | BPF_IMM:
751                         /* X <- k */
752                         ctx->flags |= SEEN_X;
753                         emit_load_imm(r_X, k, ctx);
754                         break;
755                 case BPF_LDX | BPF_MEM:
756                         /* X <- M[k] */
757                         ctx->flags |= SEEN_X | SEEN_MEM;
758                         emit_load(r_X, r_M, SCRATCH_OFF(k), ctx);
759                         break;
760                 case BPF_LDX | BPF_W | BPF_LEN:
761                         /* X <- len */
762                         ctx->flags |= SEEN_X | SEEN_SKB;
763                         off = offsetof(struct sk_buff, len);
764                         emit_load(r_X, r_skb, off, ctx);
765                         break;
766                 case BPF_LDX | BPF_B | BPF_MSH:
767                         /* X <- 4 * (P[k:1] & 0xf) */
768                         ctx->flags |= SEEN_X | SEEN_CALL | SEEN_SKB;
769                         /* Load offset to a1 */
770                         emit_load_func(r_s0, (ptr)sk_load_byte, ctx);
771                         /*
772                          * This may emit two instructions so it may not fit
773                          * in the delay slot. So use a0 in the delay slot.
774                          */
775                         emit_load_imm(MIPS_R_A1, k, ctx);
776                         emit_jalr(MIPS_R_RA, r_s0, ctx);
777                         emit_reg_move(MIPS_R_A0, r_skb, ctx); /* delay slot */
778                         /* Check the error value */
779                         emit_bcond(MIPS_COND_NE, r_ret, 0,
780                                    b_imm(prog->len, ctx), ctx);
781                         emit_reg_move(r_ret, r_zero, ctx);
782                         /* We are good */
783                         /* X <- P[1:K] & 0xf */
784                         emit_andi(r_X, r_A, 0xf, ctx);
785                         /* X << 2 */
786                         emit_b(b_imm(i + 1, ctx), ctx);
787                         emit_sll(r_X, r_X, 2, ctx); /* delay slot */
788                         break;
789                 case BPF_ST:
790                         /* M[k] <- A */
791                         ctx->flags |= SEEN_MEM | SEEN_A;
792                         emit_store(r_A, r_M, SCRATCH_OFF(k), ctx);
793                         break;
794                 case BPF_STX:
795                         /* M[k] <- X */
796                         ctx->flags |= SEEN_MEM | SEEN_X;
797                         emit_store(r_X, r_M, SCRATCH_OFF(k), ctx);
798                         break;
799                 case BPF_ALU | BPF_ADD | BPF_K:
800                         /* A += K */
801                         ctx->flags |= SEEN_A;
802                         emit_addiu(r_A, r_A, k, ctx);
803                         break;
804                 case BPF_ALU | BPF_ADD | BPF_X:
805                         /* A += X */
806                         ctx->flags |= SEEN_A | SEEN_X;
807                         emit_addu(r_A, r_A, r_X, ctx);
808                         break;
809                 case BPF_ALU | BPF_SUB | BPF_K:
810                         /* A -= K */
811                         ctx->flags |= SEEN_A;
812                         emit_addiu(r_A, r_A, -k, ctx);
813                         break;
814                 case BPF_ALU | BPF_SUB | BPF_X:
815                         /* A -= X */
816                         ctx->flags |= SEEN_A | SEEN_X;
817                         emit_subu(r_A, r_A, r_X, ctx);
818                         break;
819                 case BPF_ALU | BPF_MUL | BPF_K:
820                         /* A *= K */
821                         /* Load K to scratch register before MUL */
822                         ctx->flags |= SEEN_A;
823                         emit_load_imm(r_s0, k, ctx);
824                         emit_mul(r_A, r_A, r_s0, ctx);
825                         break;
826                 case BPF_ALU | BPF_MUL | BPF_X:
827                         /* A *= X */
828                         ctx->flags |= SEEN_A | SEEN_X;
829                         emit_mul(r_A, r_A, r_X, ctx);
830                         break;
831                 case BPF_ALU | BPF_DIV | BPF_K:
832                         /* A /= k */
833                         if (k == 1)
834                                 break;
835                         if (optimize_div(&k)) {
836                                 ctx->flags |= SEEN_A;
837                                 emit_srl(r_A, r_A, k, ctx);
838                                 break;
839                         }
840                         ctx->flags |= SEEN_A;
841                         emit_load_imm(r_s0, k, ctx);
842                         emit_div(r_A, r_s0, ctx);
843                         break;
844                 case BPF_ALU | BPF_MOD | BPF_K:
845                         /* A %= k */
846                         if (k == 1) {
847                                 ctx->flags |= SEEN_A;
848                                 emit_jit_reg_move(r_A, r_zero, ctx);
849                         } else {
850                                 ctx->flags |= SEEN_A;
851                                 emit_load_imm(r_s0, k, ctx);
852                                 emit_mod(r_A, r_s0, ctx);
853                         }
854                         break;
855                 case BPF_ALU | BPF_DIV | BPF_X:
856                         /* A /= X */
857                         ctx->flags |= SEEN_X | SEEN_A;
858                         /* Check if r_X is zero */
859                         emit_bcond(MIPS_COND_EQ, r_X, r_zero,
860                                    b_imm(prog->len, ctx), ctx);
861                         emit_load_imm(r_ret, 0, ctx); /* delay slot */
862                         emit_div(r_A, r_X, ctx);
863                         break;
864                 case BPF_ALU | BPF_MOD | BPF_X:
865                         /* A %= X */
866                         ctx->flags |= SEEN_X | SEEN_A;
867                         /* Check if r_X is zero */
868                         emit_bcond(MIPS_COND_EQ, r_X, r_zero,
869                                    b_imm(prog->len, ctx), ctx);
870                         emit_load_imm(r_ret, 0, ctx); /* delay slot */
871                         emit_mod(r_A, r_X, ctx);
872                         break;
873                 case BPF_ALU | BPF_OR | BPF_K:
874                         /* A |= K */
875                         ctx->flags |= SEEN_A;
876                         emit_ori(r_A, r_A, k, ctx);
877                         break;
878                 case BPF_ALU | BPF_OR | BPF_X:
879                         /* A |= X */
880                         ctx->flags |= SEEN_A;
881                         emit_ori(r_A, r_A, r_X, ctx);
882                         break;
883                 case BPF_ALU | BPF_XOR | BPF_K:
884                         /* A ^= k */
885                         ctx->flags |= SEEN_A;
886                         emit_xori(r_A, r_A, k, ctx);
887                         break;
888                 case BPF_ANC | SKF_AD_ALU_XOR_X:
889                 case BPF_ALU | BPF_XOR | BPF_X:
890                         /* A ^= X */
891                         ctx->flags |= SEEN_A;
892                         emit_xor(r_A, r_A, r_X, ctx);
893                         break;
894                 case BPF_ALU | BPF_AND | BPF_K:
895                         /* A &= K */
896                         ctx->flags |= SEEN_A;
897                         emit_andi(r_A, r_A, k, ctx);
898                         break;
899                 case BPF_ALU | BPF_AND | BPF_X:
900                         /* A &= X */
901                         ctx->flags |= SEEN_A | SEEN_X;
902                         emit_and(r_A, r_A, r_X, ctx);
903                         break;
904                 case BPF_ALU | BPF_LSH | BPF_K:
905                         /* A <<= K */
906                         ctx->flags |= SEEN_A;
907                         emit_sll(r_A, r_A, k, ctx);
908                         break;
909                 case BPF_ALU | BPF_LSH | BPF_X:
910                         /* A <<= X */
911                         ctx->flags |= SEEN_A | SEEN_X;
912                         emit_sllv(r_A, r_A, r_X, ctx);
913                         break;
914                 case BPF_ALU | BPF_RSH | BPF_K:
915                         /* A >>= K */
916                         ctx->flags |= SEEN_A;
917                         emit_srl(r_A, r_A, k, ctx);
918                         break;
919                 case BPF_ALU | BPF_RSH | BPF_X:
920                         ctx->flags |= SEEN_A | SEEN_X;
921                         emit_srlv(r_A, r_A, r_X, ctx);
922                         break;
923                 case BPF_ALU | BPF_NEG:
924                         /* A = -A */
925                         ctx->flags |= SEEN_A;
926                         emit_neg(r_A, ctx);
927                         break;
928                 case BPF_JMP | BPF_JA:
929                         /* pc += K */
930                         emit_b(b_imm(i + k + 1, ctx), ctx);
931                         emit_nop(ctx);
932                         break;
933                 case BPF_JMP | BPF_JEQ | BPF_K:
934                         /* pc += ( A == K ) ? pc->jt : pc->jf */
935                         condt = MIPS_COND_EQ | MIPS_COND_K;
936                         goto jmp_cmp;
937                 case BPF_JMP | BPF_JEQ | BPF_X:
938                         ctx->flags |= SEEN_X;
939                         /* pc += ( A == X ) ? pc->jt : pc->jf */
940                         condt = MIPS_COND_EQ | MIPS_COND_X;
941                         goto jmp_cmp;
942                 case BPF_JMP | BPF_JGE | BPF_K:
943                         /* pc += ( A >= K ) ? pc->jt : pc->jf */
944                         condt = MIPS_COND_GE | MIPS_COND_K;
945                         goto jmp_cmp;
946                 case BPF_JMP | BPF_JGE | BPF_X:
947                         ctx->flags |= SEEN_X;
948                         /* pc += ( A >= X ) ? pc->jt : pc->jf */
949                         condt = MIPS_COND_GE | MIPS_COND_X;
950                         goto jmp_cmp;
951                 case BPF_JMP | BPF_JGT | BPF_K:
952                         /* pc += ( A > K ) ? pc->jt : pc->jf */
953                         condt = MIPS_COND_GT | MIPS_COND_K;
954                         goto jmp_cmp;
955                 case BPF_JMP | BPF_JGT | BPF_X:
956                         ctx->flags |= SEEN_X;
957                         /* pc += ( A > X ) ? pc->jt : pc->jf */
958                         condt = MIPS_COND_GT | MIPS_COND_X;
959 jmp_cmp:
960                         /* Greater or Equal */
961                         if ((condt & MIPS_COND_GE) ||
962                             (condt & MIPS_COND_GT)) {
963                                 if (condt & MIPS_COND_K) { /* K */
964                                         ctx->flags |= SEEN_A;
965                                         emit_sltiu(r_s0, r_A, k, ctx);
966                                 } else { /* X */
967                                         ctx->flags |= SEEN_A |
968                                                 SEEN_X;
969                                         emit_sltu(r_s0, r_A, r_X, ctx);
970                                 }
971                                 /* A < (K|X) ? r_scrach = 1 */
972                                 b_off = b_imm(i + inst->jf + 1, ctx);
973                                 emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off,
974                                            ctx);
975                                 emit_nop(ctx);
976                                 /* A > (K|X) ? scratch = 0 */
977                                 if (condt & MIPS_COND_GT) {
978                                         /* Checking for equality */
979                                         ctx->flags |= SEEN_A | SEEN_X;
980                                         if (condt & MIPS_COND_K)
981                                                 emit_load_imm(r_s0, k, ctx);
982                                         else
983                                                 emit_jit_reg_move(r_s0, r_X,
984                                                                   ctx);
985                                         b_off = b_imm(i + inst->jf + 1, ctx);
986                                         emit_bcond(MIPS_COND_EQ, r_A, r_s0,
987                                                    b_off, ctx);
988                                         emit_nop(ctx);
989                                         /* Finally, A > K|X */
990                                         b_off = b_imm(i + inst->jt + 1, ctx);
991                                         emit_b(b_off, ctx);
992                                         emit_nop(ctx);
993                                 } else {
994                                         /* A >= (K|X) so jump */
995                                         b_off = b_imm(i + inst->jt + 1, ctx);
996                                         emit_b(b_off, ctx);
997                                         emit_nop(ctx);
998                                 }
999                         } else {
1000                                 /* A == K|X */
1001                                 if (condt & MIPS_COND_K) { /* K */
1002                                         ctx->flags |= SEEN_A;
1003                                         emit_load_imm(r_s0, k, ctx);
1004                                         /* jump true */
1005                                         b_off = b_imm(i + inst->jt + 1, ctx);
1006                                         emit_bcond(MIPS_COND_EQ, r_A, r_s0,
1007                                                    b_off, ctx);
1008                                         emit_nop(ctx);
1009                                         /* jump false */
1010                                         b_off = b_imm(i + inst->jf + 1,
1011                                                       ctx);
1012                                         emit_bcond(MIPS_COND_NE, r_A, r_s0,
1013                                                    b_off, ctx);
1014                                         emit_nop(ctx);
1015                                 } else { /* X */
1016                                         /* jump true */
1017                                         ctx->flags |= SEEN_A | SEEN_X;
1018                                         b_off = b_imm(i + inst->jt + 1,
1019                                                       ctx);
1020                                         emit_bcond(MIPS_COND_EQ, r_A, r_X,
1021                                                    b_off, ctx);
1022                                         emit_nop(ctx);
1023                                         /* jump false */
1024                                         b_off = b_imm(i + inst->jf + 1, ctx);
1025                                         emit_bcond(MIPS_COND_NE, r_A, r_X,
1026                                                    b_off, ctx);
1027                                         emit_nop(ctx);
1028                                 }
1029                         }
1030                         break;
1031                 case BPF_JMP | BPF_JSET | BPF_K:
1032                         ctx->flags |= SEEN_A;
1033                         /* pc += (A & K) ? pc -> jt : pc -> jf */
1034                         emit_load_imm(r_s1, k, ctx);
1035                         emit_and(r_s0, r_A, r_s1, ctx);
1036                         /* jump true */
1037                         b_off = b_imm(i + inst->jt + 1, ctx);
1038                         emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx);
1039                         emit_nop(ctx);
1040                         /* jump false */
1041                         b_off = b_imm(i + inst->jf + 1, ctx);
1042                         emit_b(b_off, ctx);
1043                         emit_nop(ctx);
1044                         break;
1045                 case BPF_JMP | BPF_JSET | BPF_X:
1046                         ctx->flags |= SEEN_X | SEEN_A;
1047                         /* pc += (A & X) ? pc -> jt : pc -> jf */
1048                         emit_and(r_s0, r_A, r_X, ctx);
1049                         /* jump true */
1050                         b_off = b_imm(i + inst->jt + 1, ctx);
1051                         emit_bcond(MIPS_COND_NE, r_s0, r_zero, b_off, ctx);
1052                         emit_nop(ctx);
1053                         /* jump false */
1054                         b_off = b_imm(i + inst->jf + 1, ctx);
1055                         emit_b(b_off, ctx);
1056                         emit_nop(ctx);
1057                         break;
1058                 case BPF_RET | BPF_A:
1059                         ctx->flags |= SEEN_A;
1060                         if (i != prog->len - 1)
1061                                 /*
1062                                  * If this is not the last instruction
1063                                  * then jump to the epilogue
1064                                  */
1065                                 emit_b(b_imm(prog->len, ctx), ctx);
1066                         emit_reg_move(r_ret, r_A, ctx); /* delay slot */
1067                         break;
1068                 case BPF_RET | BPF_K:
1069                         /*
1070                          * It can emit two instructions so it does not fit on
1071                          * the delay slot.
1072                          */
1073                         emit_load_imm(r_ret, k, ctx);
1074                         if (i != prog->len - 1) {
1075                                 /*
1076                                  * If this is not the last instruction
1077                                  * then jump to the epilogue
1078                                  */
1079                                 emit_b(b_imm(prog->len, ctx), ctx);
1080                                 emit_nop(ctx);
1081                         }
1082                         break;
1083                 case BPF_MISC | BPF_TAX:
1084                         /* X = A */
1085                         ctx->flags |= SEEN_X | SEEN_A;
1086                         emit_jit_reg_move(r_X, r_A, ctx);
1087                         break;
1088                 case BPF_MISC | BPF_TXA:
1089                         /* A = X */
1090                         ctx->flags |= SEEN_A | SEEN_X;
1091                         emit_jit_reg_move(r_A, r_X, ctx);
1092                         break;
1093                 /* AUX */
1094                 case BPF_ANC | SKF_AD_PROTOCOL:
1095                         /* A = ntohs(skb->protocol */
1096                         ctx->flags |= SEEN_SKB | SEEN_OFF | SEEN_A;
1097                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
1098                                                   protocol) != 2);
1099                         off = offsetof(struct sk_buff, protocol);
1100                         emit_half_load(r_A, r_skb, off, ctx);
1101 #ifdef CONFIG_CPU_LITTLE_ENDIAN
1102                         /* This needs little endian fixup */
1103                         if (cpu_has_wsbh) {
1104                                 /* R2 and later have the wsbh instruction */
1105                                 emit_wsbh(r_A, r_A, ctx);
1106                         } else {
1107                                 /* Get first byte */
1108                                 emit_andi(r_tmp_imm, r_A, 0xff, ctx);
1109                                 /* Shift it */
1110                                 emit_sll(r_tmp, r_tmp_imm, 8, ctx);
1111                                 /* Get second byte */
1112                                 emit_srl(r_tmp_imm, r_A, 8, ctx);
1113                                 emit_andi(r_tmp_imm, r_tmp_imm, 0xff, ctx);
1114                                 /* Put everyting together in r_A */
1115                                 emit_or(r_A, r_tmp, r_tmp_imm, ctx);
1116                         }
1117 #endif
1118                         break;
1119                 case BPF_ANC | SKF_AD_CPU:
1120                         ctx->flags |= SEEN_A | SEEN_OFF;
1121                         /* A = current_thread_info()->cpu */
1122                         BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info,
1123                                                   cpu) != 4);
1124                         off = offsetof(struct thread_info, cpu);
1125                         /* $28/gp points to the thread_info struct */
1126                         emit_load(r_A, 28, off, ctx);
1127                         break;
1128                 case BPF_ANC | SKF_AD_IFINDEX:
1129                         /* A = skb->dev->ifindex */
1130                         ctx->flags |= SEEN_SKB | SEEN_A;
1131                         off = offsetof(struct sk_buff, dev);
1132                         /* Load *dev pointer */
1133                         emit_load_ptr(r_s0, r_skb, off, ctx);
1134                         /* error (0) in the delay slot */
1135                         emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
1136                                    b_imm(prog->len, ctx), ctx);
1137                         emit_reg_move(r_ret, r_zero, ctx);
1138                         BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
1139                                                   ifindex) != 4);
1140                         off = offsetof(struct net_device, ifindex);
1141                         emit_load(r_A, r_s0, off, ctx);
1142                         break;
1143                 case BPF_ANC | SKF_AD_MARK:
1144                         ctx->flags |= SEEN_SKB | SEEN_A;
1145                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
1146                         off = offsetof(struct sk_buff, mark);
1147                         emit_load(r_A, r_skb, off, ctx);
1148                         break;
1149                 case BPF_ANC | SKF_AD_RXHASH:
1150                         ctx->flags |= SEEN_SKB | SEEN_A;
1151                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
1152                         off = offsetof(struct sk_buff, hash);
1153                         emit_load(r_A, r_skb, off, ctx);
1154                         break;
1155                 case BPF_ANC | SKF_AD_VLAN_TAG:
1156                 case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
1157                         ctx->flags |= SEEN_SKB | SEEN_A;
1158                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
1159                                                   vlan_tci) != 2);
1160                         off = offsetof(struct sk_buff, vlan_tci);
1161                         emit_half_load(r_s0, r_skb, off, ctx);
1162                         if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
1163                                 emit_andi(r_A, r_s0, (u16)~VLAN_TAG_PRESENT, ctx);
1164                         } else {
1165                                 emit_andi(r_A, r_s0, VLAN_TAG_PRESENT, ctx);
1166                                 /* return 1 if present */
1167                                 emit_sltu(r_A, r_zero, r_A, ctx);
1168                         }
1169                         break;
1170                 case BPF_ANC | SKF_AD_PKTTYPE:
1171                         ctx->flags |= SEEN_SKB;
1172 
1173                         emit_load_byte(r_tmp, r_skb, PKT_TYPE_OFFSET(), ctx);
1174                         /* Keep only the last 3 bits */
1175                         emit_andi(r_A, r_tmp, PKT_TYPE_MAX, ctx);
1176 #ifdef __BIG_ENDIAN_BITFIELD
1177                         /* Get the actual packet type to the lower 3 bits */
1178                         emit_srl(r_A, r_A, 5, ctx);
1179 #endif
1180                         break;
1181                 case BPF_ANC | SKF_AD_QUEUE:
1182                         ctx->flags |= SEEN_SKB | SEEN_A;
1183                         BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
1184                                                   queue_mapping) != 2);
1185                         BUILD_BUG_ON(offsetof(struct sk_buff,
1186                                               queue_mapping) > 0xff);
1187                         off = offsetof(struct sk_buff, queue_mapping);
1188                         emit_half_load(r_A, r_skb, off, ctx);
1189                         break;
1190                 default:
1191                         pr_debug("%s: Unhandled opcode: 0x%02x\n", __FILE__,
1192                                  inst->code);
1193                         return -1;
1194                 }
1195         }
1196 
1197         /* compute offsets only during the first pass */
1198         if (ctx->target == NULL)
1199                 ctx->offsets[i] = ctx->idx * 4;
1200 
1201         return 0;
1202 }
1203 
1204 int bpf_jit_enable __read_mostly;
1205 
1206 void bpf_jit_compile(struct bpf_prog *fp)
1207 {
1208         struct jit_ctx ctx;
1209         unsigned int alloc_size, tmp_idx;
1210 
1211         if (!bpf_jit_enable)
1212                 return;
1213 
1214         memset(&ctx, 0, sizeof(ctx));
1215 
1216         ctx.offsets = kcalloc(fp->len, sizeof(*ctx.offsets), GFP_KERNEL);
1217         if (ctx.offsets == NULL)
1218                 return;
1219 
1220         ctx.skf = fp;
1221 
1222         if (build_body(&ctx))
1223                 goto out;
1224 
1225         tmp_idx = ctx.idx;
1226         build_prologue(&ctx);
1227         ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4;
1228         /* just to complete the ctx.idx count */
1229         build_epilogue(&ctx);
1230 
1231         alloc_size = 4 * ctx.idx;
1232         ctx.target = module_alloc(alloc_size);
1233         if (ctx.target == NULL)
1234                 goto out;
1235 
1236         /* Clean it */
1237         memset(ctx.target, 0, alloc_size);
1238 
1239         ctx.idx = 0;
1240 
1241         /* Generate the actual JIT code */
1242         build_prologue(&ctx);
1243         build_body(&ctx);
1244         build_epilogue(&ctx);
1245 
1246         /* Update the icache */
1247         flush_icache_range((ptr)ctx.target, (ptr)(ctx.target + ctx.idx));
1248 
1249         if (bpf_jit_enable > 1)
1250                 /* Dump JIT code */
1251                 bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
1252 
1253         fp->bpf_func = (void *)ctx.target;
1254         fp->jited = true;
1255 
1256 out:
1257         kfree(ctx.offsets);
1258 }
1259 
1260 void bpf_jit_free(struct bpf_prog *fp)
1261 {
1262         if (fp->jited)
1263                 module_memfree(fp->bpf_func);
1264 
1265         bpf_prog_unlock_free(fp);
1266 }
1267 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp