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1/*
2 * Just-In-Time compiler for BPF filters on 32bit ARM
3 *
4 * Copyright (c) 2011 Mircea Gherzan <mgherzan@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; version 2 of the License.
9 */
10
11#include <linux/bitops.h>
12#include <linux/compiler.h>
13#include <linux/errno.h>
14#include <linux/filter.h>
15#include <linux/moduleloader.h>
16#include <linux/netdevice.h>
17#include <linux/string.h>
18#include <linux/slab.h>
19#include <asm/cacheflush.h>
20#include <asm/hwcap.h>
21
22#include "bpf_jit_32.h"
23
24/*
25 * ABI:
26 *
27 * r0 scratch register
28 * r4 BPF register A
29 * r5 BPF register X
30 * r6 pointer to the skb
31 * r7 skb->data
32 * r8 skb_headlen(skb)
33 */
34
35#define r_scratch ARM_R0
36/* r1-r3 are (also) used for the unaligned loads on the non-ARMv7 slowpath */
37#define r_off ARM_R1
38#define r_A ARM_R4
39#define r_X ARM_R5
40#define r_skb ARM_R6
41#define r_skb_data ARM_R7
42#define r_skb_hl ARM_R8
43
44#define SCRATCH_SP_OFFSET 0
45#define SCRATCH_OFF(k) (SCRATCH_SP_OFFSET + (k))
46
47#define SEEN_MEM ((1 << BPF_MEMWORDS) - 1)
48#define SEEN_MEM_WORD(k) (1 << (k))
49#define SEEN_X (1 << BPF_MEMWORDS)
50#define SEEN_CALL (1 << (BPF_MEMWORDS + 1))
51#define SEEN_SKB (1 << (BPF_MEMWORDS + 2))
52#define SEEN_DATA (1 << (BPF_MEMWORDS + 3))
53
54#define FLAG_NEED_X_RESET (1 << 0)
55
56struct jit_ctx {
57 const struct sk_filter *skf;
58 unsigned idx;
59 unsigned prologue_bytes;
60 int ret0_fp_idx;
61 u32 seen;
62 u32 flags;
63 u32 *offsets;
64 u32 *target;
65#if __LINUX_ARM_ARCH__ < 7
66 u16 epilogue_bytes;
67 u16 imm_count;
68 u32 *imms;
69#endif
70};
71
72int bpf_jit_enable __read_mostly;
73
74static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset)
75{
76 u8 ret;
77 int err;
78
79 err = skb_copy_bits(skb, offset, &ret, 1);
80
81 return (u64)err << 32 | ret;
82}
83
84static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset)
85{
86 u16 ret;
87 int err;
88
89 err = skb_copy_bits(skb, offset, &ret, 2);
90
91 return (u64)err << 32 | ntohs(ret);
92}
93
94static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
95{
96 u32 ret;
97 int err;
98
99 err = skb_copy_bits(skb, offset, &ret, 4);
100
101 return (u64)err << 32 | ntohl(ret);
102}
103
104/*
105 * Wrapper that handles both OABI and EABI and assures Thumb2 interworking
106 * (where the assembly routines like __aeabi_uidiv could cause problems).
107 */
108static u32 jit_udiv(u32 dividend, u32 divisor)
109{
110 return dividend / divisor;
111}
112
113static inline void _emit(int cond, u32 inst, struct jit_ctx *ctx)
114{
115 if (ctx->target != NULL)
116 ctx->target[ctx->idx] = inst | (cond << 28);
117
118 ctx->idx++;
119}
120
121/*
122 * Emit an instruction that will be executed unconditionally.
123 */
124static inline void emit(u32 inst, struct jit_ctx *ctx)
125{
126 _emit(ARM_COND_AL, inst, ctx);
127}
128
129static u16 saved_regs(struct jit_ctx *ctx)
130{
131 u16 ret = 0;
132
133 if ((ctx->skf->len > 1) ||
134 (ctx->skf->insns[0].code == BPF_S_RET_A))
135 ret |= 1 << r_A;
136
137#ifdef CONFIG_FRAME_POINTER
138 ret |= (1 << ARM_FP) | (1 << ARM_IP) | (1 << ARM_LR) | (1 << ARM_PC);
139#else
140 if (ctx->seen & SEEN_CALL)
141 ret |= 1 << ARM_LR;
142#endif
143 if (ctx->seen & (SEEN_DATA | SEEN_SKB))
144 ret |= 1 << r_skb;
145 if (ctx->seen & SEEN_DATA)
146 ret |= (1 << r_skb_data) | (1 << r_skb_hl);
147 if (ctx->seen & SEEN_X)
148 ret |= 1 << r_X;
149
150 return ret;
151}
152
153static inline int mem_words_used(struct jit_ctx *ctx)
154{
155 /* yes, we do waste some stack space IF there are "holes" in the set" */
156 return fls(ctx->seen & SEEN_MEM);
157}
158
159static inline bool is_load_to_a(u16 inst)
160{
161 switch (inst) {
162 case BPF_S_LD_W_LEN:
163 case BPF_S_LD_W_ABS:
164 case BPF_S_LD_H_ABS:
165 case BPF_S_LD_B_ABS:
166 case BPF_S_ANC_CPU:
167 case BPF_S_ANC_IFINDEX:
168 case BPF_S_ANC_MARK:
169 case BPF_S_ANC_PROTOCOL:
170 case BPF_S_ANC_RXHASH:
171 case BPF_S_ANC_QUEUE:
172 return true;
173 default:
174 return false;
175 }
176}
177
178static void build_prologue(struct jit_ctx *ctx)
179{
180 u16 reg_set = saved_regs(ctx);
181 u16 first_inst = ctx->skf->insns[0].code;
182 u16 off;
183
184#ifdef CONFIG_FRAME_POINTER
185 emit(ARM_MOV_R(ARM_IP, ARM_SP), ctx);
186 emit(ARM_PUSH(reg_set), ctx);
187 emit(ARM_SUB_I(ARM_FP, ARM_IP, 4), ctx);
188#else
189 if (reg_set)
190 emit(ARM_PUSH(reg_set), ctx);
191#endif
192
193 if (ctx->seen & (SEEN_DATA | SEEN_SKB))
194 emit(ARM_MOV_R(r_skb, ARM_R0), ctx);
195
196 if (ctx->seen & SEEN_DATA) {
197 off = offsetof(struct sk_buff, data);
198 emit(ARM_LDR_I(r_skb_data, r_skb, off), ctx);
199 /* headlen = len - data_len */
200 off = offsetof(struct sk_buff, len);
201 emit(ARM_LDR_I(r_skb_hl, r_skb, off), ctx);
202 off = offsetof(struct sk_buff, data_len);
203 emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
204 emit(ARM_SUB_R(r_skb_hl, r_skb_hl, r_scratch), ctx);
205 }
206
207 if (ctx->flags & FLAG_NEED_X_RESET)
208 emit(ARM_MOV_I(r_X, 0), ctx);
209
210 /* do not leak kernel data to userspace */
211 if ((first_inst != BPF_S_RET_K) && !(is_load_to_a(first_inst)))
212 emit(ARM_MOV_I(r_A, 0), ctx);
213
214 /* stack space for the BPF_MEM words */
215 if (ctx->seen & SEEN_MEM)
216 emit(ARM_SUB_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx);
217}
218
219static void build_epilogue(struct jit_ctx *ctx)
220{
221 u16 reg_set = saved_regs(ctx);
222
223 if (ctx->seen & SEEN_MEM)
224 emit(ARM_ADD_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx);
225
226 reg_set &= ~(1 << ARM_LR);
227
228#ifdef CONFIG_FRAME_POINTER
229 /* the first instruction of the prologue was: mov ip, sp */
230 reg_set &= ~(1 << ARM_IP);
231 reg_set |= (1 << ARM_SP);
232 emit(ARM_LDM(ARM_SP, reg_set), ctx);
233#else
234 if (reg_set) {
235 if (ctx->seen & SEEN_CALL)
236 reg_set |= 1 << ARM_PC;
237 emit(ARM_POP(reg_set), ctx);
238 }
239
240 if (!(ctx->seen & SEEN_CALL))
241 emit(ARM_BX(ARM_LR), ctx);
242#endif
243}
244
245static int16_t imm8m(u32 x)
246{
247 u32 rot;
248
249 for (rot = 0; rot < 16; rot++)
250 if ((x & ~ror32(0xff, 2 * rot)) == 0)
251 return rol32(x, 2 * rot) | (rot << 8);
252
253 return -1;
254}
255
256#if __LINUX_ARM_ARCH__ < 7
257
258static u16 imm_offset(u32 k, struct jit_ctx *ctx)
259{
260 unsigned i = 0, offset;
261 u16 imm;
262
263 /* on the "fake" run we just count them (duplicates included) */
264 if (ctx->target == NULL) {
265 ctx->imm_count++;
266 return 0;
267 }
268
269 while ((i < ctx->imm_count) && ctx->imms[i]) {
270 if (ctx->imms[i] == k)
271 break;
272 i++;
273 }
274
275 if (ctx->imms[i] == 0)
276 ctx->imms[i] = k;
277
278 /* constants go just after the epilogue */
279 offset = ctx->offsets[ctx->skf->len];
280 offset += ctx->prologue_bytes;
281 offset += ctx->epilogue_bytes;
282 offset += i * 4;
283
284 ctx->target[offset / 4] = k;
285
286 /* PC in ARM mode == address of the instruction + 8 */
287 imm = offset - (8 + ctx->idx * 4);
288
289 return imm;
290}
291
292#endif /* __LINUX_ARM_ARCH__ */
293
294/*
295 * Move an immediate that's not an imm8m to a core register.
296 */
297static inline void emit_mov_i_no8m(int rd, u32 val, struct jit_ctx *ctx)
298{
299#if __LINUX_ARM_ARCH__ < 7
300 emit(ARM_LDR_I(rd, ARM_PC, imm_offset(val, ctx)), ctx);
301#else
302 emit(ARM_MOVW(rd, val & 0xffff), ctx);
303 if (val > 0xffff)
304 emit(ARM_MOVT(rd, val >> 16), ctx);
305#endif
306}
307
308static inline void emit_mov_i(int rd, u32 val, struct jit_ctx *ctx)
309{
310 int imm12 = imm8m(val);
311
312 if (imm12 >= 0)
313 emit(ARM_MOV_I(rd, imm12), ctx);
314 else
315 emit_mov_i_no8m(rd, val, ctx);
316}
317
318#if __LINUX_ARM_ARCH__ < 6
319
320static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
321{
322 _emit(cond, ARM_LDRB_I(ARM_R3, r_addr, 1), ctx);
323 _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx);
324 _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 3), ctx);
325 _emit(cond, ARM_LSL_I(ARM_R3, ARM_R3, 16), ctx);
326 _emit(cond, ARM_LDRB_I(ARM_R0, r_addr, 2), ctx);
327 _emit(cond, ARM_ORR_S(ARM_R3, ARM_R3, ARM_R1, SRTYPE_LSL, 24), ctx);
328 _emit(cond, ARM_ORR_R(ARM_R3, ARM_R3, ARM_R2), ctx);
329 _emit(cond, ARM_ORR_S(r_res, ARM_R3, ARM_R0, SRTYPE_LSL, 8), ctx);
330}
331
332static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
333{
334 _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx);
335 _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 1), ctx);
336 _emit(cond, ARM_ORR_S(r_res, ARM_R2, ARM_R1, SRTYPE_LSL, 8), ctx);
337}
338
339static inline void emit_swap16(u8 r_dst, u8 r_src, struct jit_ctx *ctx)
340{
341 emit(ARM_LSL_R(ARM_R1, r_src, 8), ctx);
342 emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSL, 8), ctx);
343 emit(ARM_LSL_I(r_dst, r_dst, 8), ctx);
344 emit(ARM_LSL_R(r_dst, r_dst, 8), ctx);
345}
346
347#else /* ARMv6+ */
348
349static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
350{
351 _emit(cond, ARM_LDR_I(r_res, r_addr, 0), ctx);
352#ifdef __LITTLE_ENDIAN
353 _emit(cond, ARM_REV(r_res, r_res), ctx);
354#endif
355}
356
357static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
358{
359 _emit(cond, ARM_LDRH_I(r_res, r_addr, 0), ctx);
360#ifdef __LITTLE_ENDIAN
361 _emit(cond, ARM_REV16(r_res, r_res), ctx);
362#endif
363}
364
365static inline void emit_swap16(u8 r_dst __maybe_unused,
366 u8 r_src __maybe_unused,
367 struct jit_ctx *ctx __maybe_unused)
368{
369#ifdef __LITTLE_ENDIAN
370 emit(ARM_REV16(r_dst, r_src), ctx);
371#endif
372}
373
374#endif /* __LINUX_ARM_ARCH__ < 6 */
375
376
377/* Compute the immediate value for a PC-relative branch. */
378static inline u32 b_imm(unsigned tgt, struct jit_ctx *ctx)
379{
380 u32 imm;
381
382 if (ctx->target == NULL)
383 return 0;
384 /*
385 * BPF allows only forward jumps and the offset of the target is
386 * still the one computed during the first pass.
387 */
388 imm = ctx->offsets[tgt] + ctx->prologue_bytes - (ctx->idx * 4 + 8);
389
390 return imm >> 2;
391}
392
393#define OP_IMM3(op, r1, r2, imm_val, ctx) \
394 do { \
395 imm12 = imm8m(imm_val); \
396 if (imm12 < 0) { \
397 emit_mov_i_no8m(r_scratch, imm_val, ctx); \
398 emit(op ## _R((r1), (r2), r_scratch), ctx); \
399 } else { \
400 emit(op ## _I((r1), (r2), imm12), ctx); \
401 } \
402 } while (0)
403
404static inline void emit_err_ret(u8 cond, struct jit_ctx *ctx)
405{
406 if (ctx->ret0_fp_idx >= 0) {
407 _emit(cond, ARM_B(b_imm(ctx->ret0_fp_idx, ctx)), ctx);
408 /* NOP to keep the size constant between passes */
409 emit(ARM_MOV_R(ARM_R0, ARM_R0), ctx);
410 } else {
411 _emit(cond, ARM_MOV_I(ARM_R0, 0), ctx);
412 _emit(cond, ARM_B(b_imm(ctx->skf->len, ctx)), ctx);
413 }
414}
415
416static inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx)
417{
418#if __LINUX_ARM_ARCH__ < 5
419 emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx);
420
421 if (elf_hwcap & HWCAP_THUMB)
422 emit(ARM_BX(tgt_reg), ctx);
423 else
424 emit(ARM_MOV_R(ARM_PC, tgt_reg), ctx);
425#else
426 emit(ARM_BLX_R(tgt_reg), ctx);
427#endif
428}
429
430static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx)
431{
432#if __LINUX_ARM_ARCH__ == 7
433 if (elf_hwcap & HWCAP_IDIVA) {
434 emit(ARM_UDIV(rd, rm, rn), ctx);
435 return;
436 }
437#endif
438 if (rm != ARM_R0)
439 emit(ARM_MOV_R(ARM_R0, rm), ctx);
440 if (rn != ARM_R1)
441 emit(ARM_MOV_R(ARM_R1, rn), ctx);
442
443 ctx->seen |= SEEN_CALL;
444 emit_mov_i(ARM_R3, (u32)jit_udiv, ctx);
445 emit_blx_r(ARM_R3, ctx);
446
447 if (rd != ARM_R0)
448 emit(ARM_MOV_R(rd, ARM_R0), ctx);
449}
450
451static inline void update_on_xread(struct jit_ctx *ctx)
452{
453 if (!(ctx->seen & SEEN_X))
454 ctx->flags |= FLAG_NEED_X_RESET;
455
456 ctx->seen |= SEEN_X;
457}
458
459static int build_body(struct jit_ctx *ctx)
460{
461 void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w};
462 const struct sk_filter *prog = ctx->skf;
463 const struct sock_filter *inst;
464 unsigned i, load_order, off, condt;
465 int imm12;
466 u32 k;
467
468 for (i = 0; i < prog->len; i++) {
469 inst = &(prog->insns[i]);
470 /* K as an immediate value operand */
471 k = inst->k;
472
473 /* compute offsets only in the fake pass */
474 if (ctx->target == NULL)
475 ctx->offsets[i] = ctx->idx * 4;
476
477 switch (inst->code) {
478 case BPF_S_LD_IMM:
479 emit_mov_i(r_A, k, ctx);
480 break;
481 case BPF_S_LD_W_LEN:
482 ctx->seen |= SEEN_SKB;
483 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
484 emit(ARM_LDR_I(r_A, r_skb,
485 offsetof(struct sk_buff, len)), ctx);
486 break;
487 case BPF_S_LD_MEM:
488 /* A = scratch[k] */
489 ctx->seen |= SEEN_MEM_WORD(k);
490 emit(ARM_LDR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
491 break;
492 case BPF_S_LD_W_ABS:
493 load_order = 2;
494 goto load;
495 case BPF_S_LD_H_ABS:
496 load_order = 1;
497 goto load;
498 case BPF_S_LD_B_ABS:
499 load_order = 0;
500load:
501 /* the interpreter will deal with the negative K */
502 if ((int)k < 0)
503 return -ENOTSUPP;
504 emit_mov_i(r_off, k, ctx);
505load_common:
506 ctx->seen |= SEEN_DATA | SEEN_CALL;
507
508 if (load_order > 0) {
509 emit(ARM_SUB_I(r_scratch, r_skb_hl,
510 1 << load_order), ctx);
511 emit(ARM_CMP_R(r_scratch, r_off), ctx);
512 condt = ARM_COND_HS;
513 } else {
514 emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
515 condt = ARM_COND_HI;
516 }
517
518 _emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data),
519 ctx);
520
521 if (load_order == 0)
522 _emit(condt, ARM_LDRB_I(r_A, r_scratch, 0),
523 ctx);
524 else if (load_order == 1)
525 emit_load_be16(condt, r_A, r_scratch, ctx);
526 else if (load_order == 2)
527 emit_load_be32(condt, r_A, r_scratch, ctx);
528
529 _emit(condt, ARM_B(b_imm(i + 1, ctx)), ctx);
530
531 /* the slowpath */
532 emit_mov_i(ARM_R3, (u32)load_func[load_order], ctx);
533 emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
534 /* the offset is already in R1 */
535 emit_blx_r(ARM_R3, ctx);
536 /* check the result of skb_copy_bits */
537 emit(ARM_CMP_I(ARM_R1, 0), ctx);
538 emit_err_ret(ARM_COND_NE, ctx);
539 emit(ARM_MOV_R(r_A, ARM_R0), ctx);
540 break;
541 case BPF_S_LD_W_IND:
542 load_order = 2;
543 goto load_ind;
544 case BPF_S_LD_H_IND:
545 load_order = 1;
546 goto load_ind;
547 case BPF_S_LD_B_IND:
548 load_order = 0;
549load_ind:
550 OP_IMM3(ARM_ADD, r_off, r_X, k, ctx);
551 goto load_common;
552 case BPF_S_LDX_IMM:
553 ctx->seen |= SEEN_X;
554 emit_mov_i(r_X, k, ctx);
555 break;
556 case BPF_S_LDX_W_LEN:
557 ctx->seen |= SEEN_X | SEEN_SKB;
558 emit(ARM_LDR_I(r_X, r_skb,
559 offsetof(struct sk_buff, len)), ctx);
560 break;
561 case BPF_S_LDX_MEM:
562 ctx->seen |= SEEN_X | SEEN_MEM_WORD(k);
563 emit(ARM_LDR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
564 break;
565 case BPF_S_LDX_B_MSH:
566 /* x = ((*(frame + k)) & 0xf) << 2; */
567 ctx->seen |= SEEN_X | SEEN_DATA | SEEN_CALL;
568 /* the interpreter should deal with the negative K */
569 if (k < 0)
570 return -1;
571 /* offset in r1: we might have to take the slow path */
572 emit_mov_i(r_off, k, ctx);
573 emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
574
575 /* load in r0: common with the slowpath */
576 _emit(ARM_COND_HI, ARM_LDRB_R(ARM_R0, r_skb_data,
577 ARM_R1), ctx);
578 /*
579 * emit_mov_i() might generate one or two instructions,
580 * the same holds for emit_blx_r()
581 */
582 _emit(ARM_COND_HI, ARM_B(b_imm(i + 1, ctx) - 2), ctx);
583
584 emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
585 /* r_off is r1 */
586 emit_mov_i(ARM_R3, (u32)jit_get_skb_b, ctx);
587 emit_blx_r(ARM_R3, ctx);
588 /* check the return value of skb_copy_bits */
589 emit(ARM_CMP_I(ARM_R1, 0), ctx);
590 emit_err_ret(ARM_COND_NE, ctx);
591
592 emit(ARM_AND_I(r_X, ARM_R0, 0x00f), ctx);
593 emit(ARM_LSL_I(r_X, r_X, 2), ctx);
594 break;
595 case BPF_S_ST:
596 ctx->seen |= SEEN_MEM_WORD(k);
597 emit(ARM_STR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
598 break;
599 case BPF_S_STX:
600 update_on_xread(ctx);
601 ctx->seen |= SEEN_MEM_WORD(k);
602 emit(ARM_STR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
603 break;
604 case BPF_S_ALU_ADD_K:
605 /* A += K */
606 OP_IMM3(ARM_ADD, r_A, r_A, k, ctx);
607 break;
608 case BPF_S_ALU_ADD_X:
609 update_on_xread(ctx);
610 emit(ARM_ADD_R(r_A, r_A, r_X), ctx);
611 break;
612 case BPF_S_ALU_SUB_K:
613 /* A -= K */
614 OP_IMM3(ARM_SUB, r_A, r_A, k, ctx);
615 break;
616 case BPF_S_ALU_SUB_X:
617 update_on_xread(ctx);
618 emit(ARM_SUB_R(r_A, r_A, r_X), ctx);
619 break;
620 case BPF_S_ALU_MUL_K:
621 /* A *= K */
622 emit_mov_i(r_scratch, k, ctx);
623 emit(ARM_MUL(r_A, r_A, r_scratch), ctx);
624 break;
625 case BPF_S_ALU_MUL_X:
626 update_on_xread(ctx);
627 emit(ARM_MUL(r_A, r_A, r_X), ctx);
628 break;
629 case BPF_S_ALU_DIV_K:
630 /* current k == reciprocal_value(userspace k) */
631 emit_mov_i(r_scratch, k, ctx);
632 /* A = top 32 bits of the product */
633 emit(ARM_UMULL(r_scratch, r_A, r_A, r_scratch), ctx);
634 break;
635 case BPF_S_ALU_DIV_X:
636 update_on_xread(ctx);
637 emit(ARM_CMP_I(r_X, 0), ctx);
638 emit_err_ret(ARM_COND_EQ, ctx);
639 emit_udiv(r_A, r_A, r_X, ctx);
640 break;
641 case BPF_S_ALU_OR_K:
642 /* A |= K */
643 OP_IMM3(ARM_ORR, r_A, r_A, k, ctx);
644 break;
645 case BPF_S_ALU_OR_X:
646 update_on_xread(ctx);
647 emit(ARM_ORR_R(r_A, r_A, r_X), ctx);
648 break;
649 case BPF_S_ALU_AND_K:
650 /* A &= K */
651 OP_IMM3(ARM_AND, r_A, r_A, k, ctx);
652 break;
653 case BPF_S_ALU_AND_X:
654 update_on_xread(ctx);
655 emit(ARM_AND_R(r_A, r_A, r_X), ctx);
656 break;
657 case BPF_S_ALU_LSH_K:
658 if (unlikely(k > 31))
659 return -1;
660 emit(ARM_LSL_I(r_A, r_A, k), ctx);
661 break;
662 case BPF_S_ALU_LSH_X:
663 update_on_xread(ctx);
664 emit(ARM_LSL_R(r_A, r_A, r_X), ctx);
665 break;
666 case BPF_S_ALU_RSH_K:
667 if (unlikely(k > 31))
668 return -1;
669 emit(ARM_LSR_I(r_A, r_A, k), ctx);
670 break;
671 case BPF_S_ALU_RSH_X:
672 update_on_xread(ctx);
673 emit(ARM_LSR_R(r_A, r_A, r_X), ctx);
674 break;
675 case BPF_S_ALU_NEG:
676 /* A = -A */
677 emit(ARM_RSB_I(r_A, r_A, 0), ctx);
678 break;
679 case BPF_S_JMP_JA:
680 /* pc += K */
681 emit(ARM_B(b_imm(i + k + 1, ctx)), ctx);
682 break;
683 case BPF_S_JMP_JEQ_K:
684 /* pc += (A == K) ? pc->jt : pc->jf */
685 condt = ARM_COND_EQ;
686 goto cmp_imm;
687 case BPF_S_JMP_JGT_K:
688 /* pc += (A > K) ? pc->jt : pc->jf */
689 condt = ARM_COND_HI;
690 goto cmp_imm;
691 case BPF_S_JMP_JGE_K:
692 /* pc += (A >= K) ? pc->jt : pc->jf */
693 condt = ARM_COND_HS;
694cmp_imm:
695 imm12 = imm8m(k);
696 if (imm12 < 0) {
697 emit_mov_i_no8m(r_scratch, k, ctx);
698 emit(ARM_CMP_R(r_A, r_scratch), ctx);
699 } else {
700 emit(ARM_CMP_I(r_A, imm12), ctx);
701 }
702cond_jump:
703 if (inst->jt)
704 _emit(condt, ARM_B(b_imm(i + inst->jt + 1,
705 ctx)), ctx);
706 if (inst->jf)
707 _emit(condt ^ 1, ARM_B(b_imm(i + inst->jf + 1,
708 ctx)), ctx);
709 break;
710 case BPF_S_JMP_JEQ_X:
711 /* pc += (A == X) ? pc->jt : pc->jf */
712 condt = ARM_COND_EQ;
713 goto cmp_x;
714 case BPF_S_JMP_JGT_X:
715 /* pc += (A > X) ? pc->jt : pc->jf */
716 condt = ARM_COND_HI;
717 goto cmp_x;
718 case BPF_S_JMP_JGE_X:
719 /* pc += (A >= X) ? pc->jt : pc->jf */
720 condt = ARM_COND_CS;
721cmp_x:
722 update_on_xread(ctx);
723 emit(ARM_CMP_R(r_A, r_X), ctx);
724 goto cond_jump;
725 case BPF_S_JMP_JSET_K:
726 /* pc += (A & K) ? pc->jt : pc->jf */
727 condt = ARM_COND_NE;
728 /* not set iff all zeroes iff Z==1 iff EQ */
729
730 imm12 = imm8m(k);
731 if (imm12 < 0) {
732 emit_mov_i_no8m(r_scratch, k, ctx);
733 emit(ARM_TST_R(r_A, r_scratch), ctx);
734 } else {
735 emit(ARM_TST_I(r_A, imm12), ctx);
736 }
737 goto cond_jump;
738 case BPF_S_JMP_JSET_X:
739 /* pc += (A & X) ? pc->jt : pc->jf */
740 update_on_xread(ctx);
741 condt = ARM_COND_NE;
742 emit(ARM_TST_R(r_A, r_X), ctx);
743 goto cond_jump;
744 case BPF_S_RET_A:
745 emit(ARM_MOV_R(ARM_R0, r_A), ctx);
746 goto b_epilogue;
747 case BPF_S_RET_K:
748 if ((k == 0) && (ctx->ret0_fp_idx < 0))
749 ctx->ret0_fp_idx = i;
750 emit_mov_i(ARM_R0, k, ctx);
751b_epilogue:
752 if (i != ctx->skf->len - 1)
753 emit(ARM_B(b_imm(prog->len, ctx)), ctx);
754 break;
755 case BPF_S_MISC_TAX:
756 /* X = A */
757 ctx->seen |= SEEN_X;
758 emit(ARM_MOV_R(r_X, r_A), ctx);
759 break;
760 case BPF_S_MISC_TXA:
761 /* A = X */
762 update_on_xread(ctx);
763 emit(ARM_MOV_R(r_A, r_X), ctx);
764 break;
765 case BPF_S_ANC_ALU_XOR_X:
766 /* A ^= X */
767 update_on_xread(ctx);
768 emit(ARM_EOR_R(r_A, r_A, r_X), ctx);
769 break;
770 case BPF_S_ANC_PROTOCOL:
771 /* A = ntohs(skb->protocol) */
772 ctx->seen |= SEEN_SKB;
773 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
774 protocol) != 2);
775 off = offsetof(struct sk_buff, protocol);
776 emit(ARM_LDRH_I(r_scratch, r_skb, off), ctx);
777 emit_swap16(r_A, r_scratch, ctx);
778 break;
779 case BPF_S_ANC_CPU:
780 /* r_scratch = current_thread_info() */
781 OP_IMM3(ARM_BIC, r_scratch, ARM_SP, THREAD_SIZE - 1, ctx);
782 /* A = current_thread_info()->cpu */
783 BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4);
784 off = offsetof(struct thread_info, cpu);
785 emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
786 break;
787 case BPF_S_ANC_IFINDEX:
788 /* A = skb->dev->ifindex */
789 ctx->seen |= SEEN_SKB;
790 off = offsetof(struct sk_buff, dev);
791 emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
792
793 emit(ARM_CMP_I(r_scratch, 0), ctx);
794 emit_err_ret(ARM_COND_EQ, ctx);
795
796 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
797 ifindex) != 4);
798 off = offsetof(struct net_device, ifindex);
799 emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
800 break;
801 case BPF_S_ANC_MARK:
802 ctx->seen |= SEEN_SKB;
803 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
804 off = offsetof(struct sk_buff, mark);
805 emit(ARM_LDR_I(r_A, r_skb, off), ctx);
806 break;
807 case BPF_S_ANC_RXHASH:
808 ctx->seen |= SEEN_SKB;
809 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
810 off = offsetof(struct sk_buff, rxhash);
811 emit(ARM_LDR_I(r_A, r_skb, off), ctx);
812 break;
813 case BPF_S_ANC_QUEUE:
814 ctx->seen |= SEEN_SKB;
815 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
816 queue_mapping) != 2);
817 BUILD_BUG_ON(offsetof(struct sk_buff,
818 queue_mapping) > 0xff);
819 off = offsetof(struct sk_buff, queue_mapping);
820 emit(ARM_LDRH_I(r_A, r_skb, off), ctx);
821 break;
822 default:
823 return -1;
824 }
825 }
826
827 /* compute offsets only during the first pass */
828 if (ctx->target == NULL)
829 ctx->offsets[i] = ctx->idx * 4;
830
831 return 0;
832}
833
834
835void bpf_jit_compile(struct sk_filter *fp)
836{
837 struct jit_ctx ctx;
838 unsigned tmp_idx;
839 unsigned alloc_size;
840
841 if (!bpf_jit_enable)
842 return;
843
844 memset(&ctx, 0, sizeof(ctx));
845 ctx.skf = fp;
846 ctx.ret0_fp_idx = -1;
847
848 ctx.offsets = kzalloc(GFP_KERNEL, 4 * (ctx.skf->len + 1));
849 if (ctx.offsets == NULL)
850 return;
851
852 /* fake pass to fill in the ctx->seen */
853 if (unlikely(build_body(&ctx)))
854 goto out;
855
856 tmp_idx = ctx.idx;
857 build_prologue(&ctx);
858 ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4;
859
860#if __LINUX_ARM_ARCH__ < 7
861 tmp_idx = ctx.idx;
862 build_epilogue(&ctx);
863 ctx.epilogue_bytes = (ctx.idx - tmp_idx) * 4;
864
865 ctx.idx += ctx.imm_count;
866 if (ctx.imm_count) {
867 ctx.imms = kzalloc(GFP_KERNEL, 4 * ctx.imm_count);
868 if (ctx.imms == NULL)
869 goto out;
870 }
871#else
872 /* there's nothing after the epilogue on ARMv7 */
873 build_epilogue(&ctx);
874#endif
875
876 alloc_size = 4 * ctx.idx;
877 ctx.target = module_alloc(max(sizeof(struct work_struct),
878 alloc_size));
879 if (unlikely(ctx.target == NULL))
880 goto out;
881
882 ctx.idx = 0;
883 build_prologue(&ctx);
884 build_body(&ctx);
885 build_epilogue(&ctx);
886
887 flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx));
888
889#if __LINUX_ARM_ARCH__ < 7
890 if (ctx.imm_count)
891 kfree(ctx.imms);
892#endif
893
894 if (bpf_jit_enable > 1)
895 print_hex_dump(KERN_INFO, "BPF JIT code: ",
896 DUMP_PREFIX_ADDRESS, 16, 4, ctx.target,
897 alloc_size, false);
898
899 fp->bpf_func = (void *)ctx.target;
900out:
901 kfree(ctx.offsets);
902 return;
903}
904
905static void bpf_jit_free_worker(struct work_struct *work)
906{
907 module_free(NULL, work);
908}
909
910void bpf_jit_free(struct sk_filter *fp)
911{
912 struct work_struct *work;
913
914 if (fp->bpf_func != sk_run_filter) {
915 work = (struct work_struct *)fp->bpf_func;
916
917 INIT_WORK(work, bpf_jit_free_worker);
918 schedule_work(work);
919 }
920}