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[mirror_ubuntu-jammy-kernel.git] / arch / arm / net / bpf_jit_32.c
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 <linux/if_vlan.h>
20 #include <asm/cacheflush.h>
21 #include <asm/hwcap.h>
22 #include <asm/opcodes.h>
23
24 #include "bpf_jit_32.h"
25
26 /*
27 * ABI:
28 *
29 * r0 scratch register
30 * r4 BPF register A
31 * r5 BPF register X
32 * r6 pointer to the skb
33 * r7 skb->data
34 * r8 skb_headlen(skb)
35 */
36
37 #define r_scratch ARM_R0
38 /* r1-r3 are (also) used for the unaligned loads on the non-ARMv7 slowpath */
39 #define r_off ARM_R1
40 #define r_A ARM_R4
41 #define r_X ARM_R5
42 #define r_skb ARM_R6
43 #define r_skb_data ARM_R7
44 #define r_skb_hl ARM_R8
45
46 #define SCRATCH_SP_OFFSET 0
47 #define SCRATCH_OFF(k) (SCRATCH_SP_OFFSET + 4 * (k))
48
49 #define SEEN_MEM ((1 << BPF_MEMWORDS) - 1)
50 #define SEEN_MEM_WORD(k) (1 << (k))
51 #define SEEN_X (1 << BPF_MEMWORDS)
52 #define SEEN_CALL (1 << (BPF_MEMWORDS + 1))
53 #define SEEN_SKB (1 << (BPF_MEMWORDS + 2))
54 #define SEEN_DATA (1 << (BPF_MEMWORDS + 3))
55
56 #define FLAG_NEED_X_RESET (1 << 0)
57
58 struct jit_ctx {
59 const struct bpf_prog *skf;
60 unsigned idx;
61 unsigned prologue_bytes;
62 int ret0_fp_idx;
63 u32 seen;
64 u32 flags;
65 u32 *offsets;
66 u32 *target;
67 #if __LINUX_ARM_ARCH__ < 7
68 u16 epilogue_bytes;
69 u16 imm_count;
70 u32 *imms;
71 #endif
72 };
73
74 int bpf_jit_enable __read_mostly;
75
76 static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset)
77 {
78 u8 ret;
79 int err;
80
81 err = skb_copy_bits(skb, offset, &ret, 1);
82
83 return (u64)err << 32 | ret;
84 }
85
86 static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset)
87 {
88 u16 ret;
89 int err;
90
91 err = skb_copy_bits(skb, offset, &ret, 2);
92
93 return (u64)err << 32 | ntohs(ret);
94 }
95
96 static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
97 {
98 u32 ret;
99 int err;
100
101 err = skb_copy_bits(skb, offset, &ret, 4);
102
103 return (u64)err << 32 | ntohl(ret);
104 }
105
106 /*
107 * Wrapper that handles both OABI and EABI and assures Thumb2 interworking
108 * (where the assembly routines like __aeabi_uidiv could cause problems).
109 */
110 static u32 jit_udiv(u32 dividend, u32 divisor)
111 {
112 return dividend / divisor;
113 }
114
115 static inline void _emit(int cond, u32 inst, struct jit_ctx *ctx)
116 {
117 inst |= (cond << 28);
118 inst = __opcode_to_mem_arm(inst);
119
120 if (ctx->target != NULL)
121 ctx->target[ctx->idx] = inst;
122
123 ctx->idx++;
124 }
125
126 /*
127 * Emit an instruction that will be executed unconditionally.
128 */
129 static inline void emit(u32 inst, struct jit_ctx *ctx)
130 {
131 _emit(ARM_COND_AL, inst, ctx);
132 }
133
134 static u16 saved_regs(struct jit_ctx *ctx)
135 {
136 u16 ret = 0;
137
138 if ((ctx->skf->len > 1) ||
139 (ctx->skf->insns[0].code == (BPF_RET | BPF_A)))
140 ret |= 1 << r_A;
141
142 #ifdef CONFIG_FRAME_POINTER
143 ret |= (1 << ARM_FP) | (1 << ARM_IP) | (1 << ARM_LR) | (1 << ARM_PC);
144 #else
145 if (ctx->seen & SEEN_CALL)
146 ret |= 1 << ARM_LR;
147 #endif
148 if (ctx->seen & (SEEN_DATA | SEEN_SKB))
149 ret |= 1 << r_skb;
150 if (ctx->seen & SEEN_DATA)
151 ret |= (1 << r_skb_data) | (1 << r_skb_hl);
152 if (ctx->seen & SEEN_X)
153 ret |= 1 << r_X;
154
155 return ret;
156 }
157
158 static inline int mem_words_used(struct jit_ctx *ctx)
159 {
160 /* yes, we do waste some stack space IF there are "holes" in the set" */
161 return fls(ctx->seen & SEEN_MEM);
162 }
163
164 static inline bool is_load_to_a(u16 inst)
165 {
166 switch (inst) {
167 case BPF_LD | BPF_W | BPF_LEN:
168 case BPF_LD | BPF_W | BPF_ABS:
169 case BPF_LD | BPF_H | BPF_ABS:
170 case BPF_LD | BPF_B | BPF_ABS:
171 return true;
172 default:
173 return false;
174 }
175 }
176
177 static void build_prologue(struct jit_ctx *ctx)
178 {
179 u16 reg_set = saved_regs(ctx);
180 u16 first_inst = ctx->skf->insns[0].code;
181 u16 off;
182
183 #ifdef CONFIG_FRAME_POINTER
184 emit(ARM_MOV_R(ARM_IP, ARM_SP), ctx);
185 emit(ARM_PUSH(reg_set), ctx);
186 emit(ARM_SUB_I(ARM_FP, ARM_IP, 4), ctx);
187 #else
188 if (reg_set)
189 emit(ARM_PUSH(reg_set), ctx);
190 #endif
191
192 if (ctx->seen & (SEEN_DATA | SEEN_SKB))
193 emit(ARM_MOV_R(r_skb, ARM_R0), ctx);
194
195 if (ctx->seen & SEEN_DATA) {
196 off = offsetof(struct sk_buff, data);
197 emit(ARM_LDR_I(r_skb_data, r_skb, off), ctx);
198 /* headlen = len - data_len */
199 off = offsetof(struct sk_buff, len);
200 emit(ARM_LDR_I(r_skb_hl, r_skb, off), ctx);
201 off = offsetof(struct sk_buff, data_len);
202 emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
203 emit(ARM_SUB_R(r_skb_hl, r_skb_hl, r_scratch), ctx);
204 }
205
206 if (ctx->flags & FLAG_NEED_X_RESET)
207 emit(ARM_MOV_I(r_X, 0), ctx);
208
209 /* do not leak kernel data to userspace */
210 if ((first_inst != (BPF_RET | BPF_K)) && !(is_load_to_a(first_inst)))
211 emit(ARM_MOV_I(r_A, 0), ctx);
212
213 /* stack space for the BPF_MEM words */
214 if (ctx->seen & SEEN_MEM)
215 emit(ARM_SUB_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx);
216 }
217
218 static void build_epilogue(struct jit_ctx *ctx)
219 {
220 u16 reg_set = saved_regs(ctx);
221
222 if (ctx->seen & SEEN_MEM)
223 emit(ARM_ADD_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx);
224
225 reg_set &= ~(1 << ARM_LR);
226
227 #ifdef CONFIG_FRAME_POINTER
228 /* the first instruction of the prologue was: mov ip, sp */
229 reg_set &= ~(1 << ARM_IP);
230 reg_set |= (1 << ARM_SP);
231 emit(ARM_LDM(ARM_SP, reg_set), ctx);
232 #else
233 if (reg_set) {
234 if (ctx->seen & SEEN_CALL)
235 reg_set |= 1 << ARM_PC;
236 emit(ARM_POP(reg_set), ctx);
237 }
238
239 if (!(ctx->seen & SEEN_CALL))
240 emit(ARM_BX(ARM_LR), ctx);
241 #endif
242 }
243
244 static int16_t imm8m(u32 x)
245 {
246 u32 rot;
247
248 for (rot = 0; rot < 16; rot++)
249 if ((x & ~ror32(0xff, 2 * rot)) == 0)
250 return rol32(x, 2 * rot) | (rot << 8);
251
252 return -1;
253 }
254
255 #if __LINUX_ARM_ARCH__ < 7
256
257 static u16 imm_offset(u32 k, struct jit_ctx *ctx)
258 {
259 unsigned i = 0, offset;
260 u16 imm;
261
262 /* on the "fake" run we just count them (duplicates included) */
263 if (ctx->target == NULL) {
264 ctx->imm_count++;
265 return 0;
266 }
267
268 while ((i < ctx->imm_count) && ctx->imms[i]) {
269 if (ctx->imms[i] == k)
270 break;
271 i++;
272 }
273
274 if (ctx->imms[i] == 0)
275 ctx->imms[i] = k;
276
277 /* constants go just after the epilogue */
278 offset = ctx->offsets[ctx->skf->len];
279 offset += ctx->prologue_bytes;
280 offset += ctx->epilogue_bytes;
281 offset += i * 4;
282
283 ctx->target[offset / 4] = k;
284
285 /* PC in ARM mode == address of the instruction + 8 */
286 imm = offset - (8 + ctx->idx * 4);
287
288 return imm;
289 }
290
291 #endif /* __LINUX_ARM_ARCH__ */
292
293 /*
294 * Move an immediate that's not an imm8m to a core register.
295 */
296 static inline void emit_mov_i_no8m(int rd, u32 val, struct jit_ctx *ctx)
297 {
298 #if __LINUX_ARM_ARCH__ < 7
299 emit(ARM_LDR_I(rd, ARM_PC, imm_offset(val, ctx)), ctx);
300 #else
301 emit(ARM_MOVW(rd, val & 0xffff), ctx);
302 if (val > 0xffff)
303 emit(ARM_MOVT(rd, val >> 16), ctx);
304 #endif
305 }
306
307 static inline void emit_mov_i(int rd, u32 val, struct jit_ctx *ctx)
308 {
309 int imm12 = imm8m(val);
310
311 if (imm12 >= 0)
312 emit(ARM_MOV_I(rd, imm12), ctx);
313 else
314 emit_mov_i_no8m(rd, val, ctx);
315 }
316
317 #if __LINUX_ARM_ARCH__ < 6
318
319 static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
320 {
321 _emit(cond, ARM_LDRB_I(ARM_R3, r_addr, 1), ctx);
322 _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx);
323 _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 3), ctx);
324 _emit(cond, ARM_LSL_I(ARM_R3, ARM_R3, 16), ctx);
325 _emit(cond, ARM_LDRB_I(ARM_R0, r_addr, 2), ctx);
326 _emit(cond, ARM_ORR_S(ARM_R3, ARM_R3, ARM_R1, SRTYPE_LSL, 24), ctx);
327 _emit(cond, ARM_ORR_R(ARM_R3, ARM_R3, ARM_R2), ctx);
328 _emit(cond, ARM_ORR_S(r_res, ARM_R3, ARM_R0, SRTYPE_LSL, 8), ctx);
329 }
330
331 static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
332 {
333 _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx);
334 _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 1), ctx);
335 _emit(cond, ARM_ORR_S(r_res, ARM_R2, ARM_R1, SRTYPE_LSL, 8), ctx);
336 }
337
338 static inline void emit_swap16(u8 r_dst, u8 r_src, struct jit_ctx *ctx)
339 {
340 /* r_dst = (r_src << 8) | (r_src >> 8) */
341 emit(ARM_LSL_I(ARM_R1, r_src, 8), ctx);
342 emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSR, 8), ctx);
343
344 /*
345 * we need to mask out the bits set in r_dst[23:16] due to
346 * the first shift instruction.
347 *
348 * note that 0x8ff is the encoded immediate 0x00ff0000.
349 */
350 emit(ARM_BIC_I(r_dst, r_dst, 0x8ff), ctx);
351 }
352
353 #else /* ARMv6+ */
354
355 static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
356 {
357 _emit(cond, ARM_LDR_I(r_res, r_addr, 0), ctx);
358 #ifdef __LITTLE_ENDIAN
359 _emit(cond, ARM_REV(r_res, r_res), ctx);
360 #endif
361 }
362
363 static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
364 {
365 _emit(cond, ARM_LDRH_I(r_res, r_addr, 0), ctx);
366 #ifdef __LITTLE_ENDIAN
367 _emit(cond, ARM_REV16(r_res, r_res), ctx);
368 #endif
369 }
370
371 static inline void emit_swap16(u8 r_dst __maybe_unused,
372 u8 r_src __maybe_unused,
373 struct jit_ctx *ctx __maybe_unused)
374 {
375 #ifdef __LITTLE_ENDIAN
376 emit(ARM_REV16(r_dst, r_src), ctx);
377 #endif
378 }
379
380 #endif /* __LINUX_ARM_ARCH__ < 6 */
381
382
383 /* Compute the immediate value for a PC-relative branch. */
384 static inline u32 b_imm(unsigned tgt, struct jit_ctx *ctx)
385 {
386 u32 imm;
387
388 if (ctx->target == NULL)
389 return 0;
390 /*
391 * BPF allows only forward jumps and the offset of the target is
392 * still the one computed during the first pass.
393 */
394 imm = ctx->offsets[tgt] + ctx->prologue_bytes - (ctx->idx * 4 + 8);
395
396 return imm >> 2;
397 }
398
399 #define OP_IMM3(op, r1, r2, imm_val, ctx) \
400 do { \
401 imm12 = imm8m(imm_val); \
402 if (imm12 < 0) { \
403 emit_mov_i_no8m(r_scratch, imm_val, ctx); \
404 emit(op ## _R((r1), (r2), r_scratch), ctx); \
405 } else { \
406 emit(op ## _I((r1), (r2), imm12), ctx); \
407 } \
408 } while (0)
409
410 static inline void emit_err_ret(u8 cond, struct jit_ctx *ctx)
411 {
412 if (ctx->ret0_fp_idx >= 0) {
413 _emit(cond, ARM_B(b_imm(ctx->ret0_fp_idx, ctx)), ctx);
414 /* NOP to keep the size constant between passes */
415 emit(ARM_MOV_R(ARM_R0, ARM_R0), ctx);
416 } else {
417 _emit(cond, ARM_MOV_I(ARM_R0, 0), ctx);
418 _emit(cond, ARM_B(b_imm(ctx->skf->len, ctx)), ctx);
419 }
420 }
421
422 static inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx)
423 {
424 #if __LINUX_ARM_ARCH__ < 5
425 emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx);
426
427 if (elf_hwcap & HWCAP_THUMB)
428 emit(ARM_BX(tgt_reg), ctx);
429 else
430 emit(ARM_MOV_R(ARM_PC, tgt_reg), ctx);
431 #else
432 emit(ARM_BLX_R(tgt_reg), ctx);
433 #endif
434 }
435
436 static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx)
437 {
438 #if __LINUX_ARM_ARCH__ == 7
439 if (elf_hwcap & HWCAP_IDIVA) {
440 emit(ARM_UDIV(rd, rm, rn), ctx);
441 return;
442 }
443 #endif
444 if (rm != ARM_R0)
445 emit(ARM_MOV_R(ARM_R0, rm), ctx);
446 if (rn != ARM_R1)
447 emit(ARM_MOV_R(ARM_R1, rn), ctx);
448
449 ctx->seen |= SEEN_CALL;
450 emit_mov_i(ARM_R3, (u32)jit_udiv, ctx);
451 emit_blx_r(ARM_R3, ctx);
452
453 if (rd != ARM_R0)
454 emit(ARM_MOV_R(rd, ARM_R0), ctx);
455 }
456
457 static inline void update_on_xread(struct jit_ctx *ctx)
458 {
459 if (!(ctx->seen & SEEN_X))
460 ctx->flags |= FLAG_NEED_X_RESET;
461
462 ctx->seen |= SEEN_X;
463 }
464
465 static int build_body(struct jit_ctx *ctx)
466 {
467 void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w};
468 const struct bpf_prog *prog = ctx->skf;
469 const struct sock_filter *inst;
470 unsigned i, load_order, off, condt;
471 int imm12;
472 u32 k;
473
474 for (i = 0; i < prog->len; i++) {
475 u16 code;
476
477 inst = &(prog->insns[i]);
478 /* K as an immediate value operand */
479 k = inst->k;
480 code = bpf_anc_helper(inst);
481
482 /* compute offsets only in the fake pass */
483 if (ctx->target == NULL)
484 ctx->offsets[i] = ctx->idx * 4;
485
486 switch (code) {
487 case BPF_LD | BPF_IMM:
488 emit_mov_i(r_A, k, ctx);
489 break;
490 case BPF_LD | BPF_W | BPF_LEN:
491 ctx->seen |= SEEN_SKB;
492 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
493 emit(ARM_LDR_I(r_A, r_skb,
494 offsetof(struct sk_buff, len)), ctx);
495 break;
496 case BPF_LD | BPF_MEM:
497 /* A = scratch[k] */
498 ctx->seen |= SEEN_MEM_WORD(k);
499 emit(ARM_LDR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
500 break;
501 case BPF_LD | BPF_W | BPF_ABS:
502 load_order = 2;
503 goto load;
504 case BPF_LD | BPF_H | BPF_ABS:
505 load_order = 1;
506 goto load;
507 case BPF_LD | BPF_B | BPF_ABS:
508 load_order = 0;
509 load:
510 /* the interpreter will deal with the negative K */
511 if ((int)k < 0)
512 return -ENOTSUPP;
513 emit_mov_i(r_off, k, ctx);
514 load_common:
515 ctx->seen |= SEEN_DATA | SEEN_CALL;
516
517 if (load_order > 0) {
518 emit(ARM_SUB_I(r_scratch, r_skb_hl,
519 1 << load_order), ctx);
520 emit(ARM_CMP_R(r_scratch, r_off), ctx);
521 condt = ARM_COND_HS;
522 } else {
523 emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
524 condt = ARM_COND_HI;
525 }
526
527 _emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data),
528 ctx);
529
530 if (load_order == 0)
531 _emit(condt, ARM_LDRB_I(r_A, r_scratch, 0),
532 ctx);
533 else if (load_order == 1)
534 emit_load_be16(condt, r_A, r_scratch, ctx);
535 else if (load_order == 2)
536 emit_load_be32(condt, r_A, r_scratch, ctx);
537
538 _emit(condt, ARM_B(b_imm(i + 1, ctx)), ctx);
539
540 /* the slowpath */
541 emit_mov_i(ARM_R3, (u32)load_func[load_order], ctx);
542 emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
543 /* the offset is already in R1 */
544 emit_blx_r(ARM_R3, ctx);
545 /* check the result of skb_copy_bits */
546 emit(ARM_CMP_I(ARM_R1, 0), ctx);
547 emit_err_ret(ARM_COND_NE, ctx);
548 emit(ARM_MOV_R(r_A, ARM_R0), ctx);
549 break;
550 case BPF_LD | BPF_W | BPF_IND:
551 load_order = 2;
552 goto load_ind;
553 case BPF_LD | BPF_H | BPF_IND:
554 load_order = 1;
555 goto load_ind;
556 case BPF_LD | BPF_B | BPF_IND:
557 load_order = 0;
558 load_ind:
559 OP_IMM3(ARM_ADD, r_off, r_X, k, ctx);
560 goto load_common;
561 case BPF_LDX | BPF_IMM:
562 ctx->seen |= SEEN_X;
563 emit_mov_i(r_X, k, ctx);
564 break;
565 case BPF_LDX | BPF_W | BPF_LEN:
566 ctx->seen |= SEEN_X | SEEN_SKB;
567 emit(ARM_LDR_I(r_X, r_skb,
568 offsetof(struct sk_buff, len)), ctx);
569 break;
570 case BPF_LDX | BPF_MEM:
571 ctx->seen |= SEEN_X | SEEN_MEM_WORD(k);
572 emit(ARM_LDR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
573 break;
574 case BPF_LDX | BPF_B | BPF_MSH:
575 /* x = ((*(frame + k)) & 0xf) << 2; */
576 ctx->seen |= SEEN_X | SEEN_DATA | SEEN_CALL;
577 /* the interpreter should deal with the negative K */
578 if ((int)k < 0)
579 return -1;
580 /* offset in r1: we might have to take the slow path */
581 emit_mov_i(r_off, k, ctx);
582 emit(ARM_CMP_R(r_skb_hl, r_off), ctx);
583
584 /* load in r0: common with the slowpath */
585 _emit(ARM_COND_HI, ARM_LDRB_R(ARM_R0, r_skb_data,
586 ARM_R1), ctx);
587 /*
588 * emit_mov_i() might generate one or two instructions,
589 * the same holds for emit_blx_r()
590 */
591 _emit(ARM_COND_HI, ARM_B(b_imm(i + 1, ctx) - 2), ctx);
592
593 emit(ARM_MOV_R(ARM_R0, r_skb), ctx);
594 /* r_off is r1 */
595 emit_mov_i(ARM_R3, (u32)jit_get_skb_b, ctx);
596 emit_blx_r(ARM_R3, ctx);
597 /* check the return value of skb_copy_bits */
598 emit(ARM_CMP_I(ARM_R1, 0), ctx);
599 emit_err_ret(ARM_COND_NE, ctx);
600
601 emit(ARM_AND_I(r_X, ARM_R0, 0x00f), ctx);
602 emit(ARM_LSL_I(r_X, r_X, 2), ctx);
603 break;
604 case BPF_ST:
605 ctx->seen |= SEEN_MEM_WORD(k);
606 emit(ARM_STR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx);
607 break;
608 case BPF_STX:
609 update_on_xread(ctx);
610 ctx->seen |= SEEN_MEM_WORD(k);
611 emit(ARM_STR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx);
612 break;
613 case BPF_ALU | BPF_ADD | BPF_K:
614 /* A += K */
615 OP_IMM3(ARM_ADD, r_A, r_A, k, ctx);
616 break;
617 case BPF_ALU | BPF_ADD | BPF_X:
618 update_on_xread(ctx);
619 emit(ARM_ADD_R(r_A, r_A, r_X), ctx);
620 break;
621 case BPF_ALU | BPF_SUB | BPF_K:
622 /* A -= K */
623 OP_IMM3(ARM_SUB, r_A, r_A, k, ctx);
624 break;
625 case BPF_ALU | BPF_SUB | BPF_X:
626 update_on_xread(ctx);
627 emit(ARM_SUB_R(r_A, r_A, r_X), ctx);
628 break;
629 case BPF_ALU | BPF_MUL | BPF_K:
630 /* A *= K */
631 emit_mov_i(r_scratch, k, ctx);
632 emit(ARM_MUL(r_A, r_A, r_scratch), ctx);
633 break;
634 case BPF_ALU | BPF_MUL | BPF_X:
635 update_on_xread(ctx);
636 emit(ARM_MUL(r_A, r_A, r_X), ctx);
637 break;
638 case BPF_ALU | BPF_DIV | BPF_K:
639 if (k == 1)
640 break;
641 emit_mov_i(r_scratch, k, ctx);
642 emit_udiv(r_A, r_A, r_scratch, ctx);
643 break;
644 case BPF_ALU | BPF_DIV | BPF_X:
645 update_on_xread(ctx);
646 emit(ARM_CMP_I(r_X, 0), ctx);
647 emit_err_ret(ARM_COND_EQ, ctx);
648 emit_udiv(r_A, r_A, r_X, ctx);
649 break;
650 case BPF_ALU | BPF_OR | BPF_K:
651 /* A |= K */
652 OP_IMM3(ARM_ORR, r_A, r_A, k, ctx);
653 break;
654 case BPF_ALU | BPF_OR | BPF_X:
655 update_on_xread(ctx);
656 emit(ARM_ORR_R(r_A, r_A, r_X), ctx);
657 break;
658 case BPF_ALU | BPF_XOR | BPF_K:
659 /* A ^= K; */
660 OP_IMM3(ARM_EOR, r_A, r_A, k, ctx);
661 break;
662 case BPF_ANC | SKF_AD_ALU_XOR_X:
663 case BPF_ALU | BPF_XOR | BPF_X:
664 /* A ^= X */
665 update_on_xread(ctx);
666 emit(ARM_EOR_R(r_A, r_A, r_X), ctx);
667 break;
668 case BPF_ALU | BPF_AND | BPF_K:
669 /* A &= K */
670 OP_IMM3(ARM_AND, r_A, r_A, k, ctx);
671 break;
672 case BPF_ALU | BPF_AND | BPF_X:
673 update_on_xread(ctx);
674 emit(ARM_AND_R(r_A, r_A, r_X), ctx);
675 break;
676 case BPF_ALU | BPF_LSH | BPF_K:
677 if (unlikely(k > 31))
678 return -1;
679 emit(ARM_LSL_I(r_A, r_A, k), ctx);
680 break;
681 case BPF_ALU | BPF_LSH | BPF_X:
682 update_on_xread(ctx);
683 emit(ARM_LSL_R(r_A, r_A, r_X), ctx);
684 break;
685 case BPF_ALU | BPF_RSH | BPF_K:
686 if (unlikely(k > 31))
687 return -1;
688 emit(ARM_LSR_I(r_A, r_A, k), ctx);
689 break;
690 case BPF_ALU | BPF_RSH | BPF_X:
691 update_on_xread(ctx);
692 emit(ARM_LSR_R(r_A, r_A, r_X), ctx);
693 break;
694 case BPF_ALU | BPF_NEG:
695 /* A = -A */
696 emit(ARM_RSB_I(r_A, r_A, 0), ctx);
697 break;
698 case BPF_JMP | BPF_JA:
699 /* pc += K */
700 emit(ARM_B(b_imm(i + k + 1, ctx)), ctx);
701 break;
702 case BPF_JMP | BPF_JEQ | BPF_K:
703 /* pc += (A == K) ? pc->jt : pc->jf */
704 condt = ARM_COND_EQ;
705 goto cmp_imm;
706 case BPF_JMP | BPF_JGT | BPF_K:
707 /* pc += (A > K) ? pc->jt : pc->jf */
708 condt = ARM_COND_HI;
709 goto cmp_imm;
710 case BPF_JMP | BPF_JGE | BPF_K:
711 /* pc += (A >= K) ? pc->jt : pc->jf */
712 condt = ARM_COND_HS;
713 cmp_imm:
714 imm12 = imm8m(k);
715 if (imm12 < 0) {
716 emit_mov_i_no8m(r_scratch, k, ctx);
717 emit(ARM_CMP_R(r_A, r_scratch), ctx);
718 } else {
719 emit(ARM_CMP_I(r_A, imm12), ctx);
720 }
721 cond_jump:
722 if (inst->jt)
723 _emit(condt, ARM_B(b_imm(i + inst->jt + 1,
724 ctx)), ctx);
725 if (inst->jf)
726 _emit(condt ^ 1, ARM_B(b_imm(i + inst->jf + 1,
727 ctx)), ctx);
728 break;
729 case BPF_JMP | BPF_JEQ | BPF_X:
730 /* pc += (A == X) ? pc->jt : pc->jf */
731 condt = ARM_COND_EQ;
732 goto cmp_x;
733 case BPF_JMP | BPF_JGT | BPF_X:
734 /* pc += (A > X) ? pc->jt : pc->jf */
735 condt = ARM_COND_HI;
736 goto cmp_x;
737 case BPF_JMP | BPF_JGE | BPF_X:
738 /* pc += (A >= X) ? pc->jt : pc->jf */
739 condt = ARM_COND_CS;
740 cmp_x:
741 update_on_xread(ctx);
742 emit(ARM_CMP_R(r_A, r_X), ctx);
743 goto cond_jump;
744 case BPF_JMP | BPF_JSET | BPF_K:
745 /* pc += (A & K) ? pc->jt : pc->jf */
746 condt = ARM_COND_NE;
747 /* not set iff all zeroes iff Z==1 iff EQ */
748
749 imm12 = imm8m(k);
750 if (imm12 < 0) {
751 emit_mov_i_no8m(r_scratch, k, ctx);
752 emit(ARM_TST_R(r_A, r_scratch), ctx);
753 } else {
754 emit(ARM_TST_I(r_A, imm12), ctx);
755 }
756 goto cond_jump;
757 case BPF_JMP | BPF_JSET | BPF_X:
758 /* pc += (A & X) ? pc->jt : pc->jf */
759 update_on_xread(ctx);
760 condt = ARM_COND_NE;
761 emit(ARM_TST_R(r_A, r_X), ctx);
762 goto cond_jump;
763 case BPF_RET | BPF_A:
764 emit(ARM_MOV_R(ARM_R0, r_A), ctx);
765 goto b_epilogue;
766 case BPF_RET | BPF_K:
767 if ((k == 0) && (ctx->ret0_fp_idx < 0))
768 ctx->ret0_fp_idx = i;
769 emit_mov_i(ARM_R0, k, ctx);
770 b_epilogue:
771 if (i != ctx->skf->len - 1)
772 emit(ARM_B(b_imm(prog->len, ctx)), ctx);
773 break;
774 case BPF_MISC | BPF_TAX:
775 /* X = A */
776 ctx->seen |= SEEN_X;
777 emit(ARM_MOV_R(r_X, r_A), ctx);
778 break;
779 case BPF_MISC | BPF_TXA:
780 /* A = X */
781 update_on_xread(ctx);
782 emit(ARM_MOV_R(r_A, r_X), ctx);
783 break;
784 case BPF_ANC | SKF_AD_PROTOCOL:
785 /* A = ntohs(skb->protocol) */
786 ctx->seen |= SEEN_SKB;
787 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
788 protocol) != 2);
789 off = offsetof(struct sk_buff, protocol);
790 emit(ARM_LDRH_I(r_scratch, r_skb, off), ctx);
791 emit_swap16(r_A, r_scratch, ctx);
792 break;
793 case BPF_ANC | SKF_AD_CPU:
794 /* r_scratch = current_thread_info() */
795 OP_IMM3(ARM_BIC, r_scratch, ARM_SP, THREAD_SIZE - 1, ctx);
796 /* A = current_thread_info()->cpu */
797 BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4);
798 off = offsetof(struct thread_info, cpu);
799 emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
800 break;
801 case BPF_ANC | SKF_AD_IFINDEX:
802 /* A = skb->dev->ifindex */
803 ctx->seen |= SEEN_SKB;
804 off = offsetof(struct sk_buff, dev);
805 emit(ARM_LDR_I(r_scratch, r_skb, off), ctx);
806
807 emit(ARM_CMP_I(r_scratch, 0), ctx);
808 emit_err_ret(ARM_COND_EQ, ctx);
809
810 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
811 ifindex) != 4);
812 off = offsetof(struct net_device, ifindex);
813 emit(ARM_LDR_I(r_A, r_scratch, off), ctx);
814 break;
815 case BPF_ANC | SKF_AD_MARK:
816 ctx->seen |= SEEN_SKB;
817 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
818 off = offsetof(struct sk_buff, mark);
819 emit(ARM_LDR_I(r_A, r_skb, off), ctx);
820 break;
821 case BPF_ANC | SKF_AD_RXHASH:
822 ctx->seen |= SEEN_SKB;
823 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
824 off = offsetof(struct sk_buff, hash);
825 emit(ARM_LDR_I(r_A, r_skb, off), ctx);
826 break;
827 case BPF_ANC | SKF_AD_VLAN_TAG:
828 case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
829 ctx->seen |= SEEN_SKB;
830 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
831 off = offsetof(struct sk_buff, vlan_tci);
832 emit(ARM_LDRH_I(r_A, r_skb, off), ctx);
833 if (code == (BPF_ANC | SKF_AD_VLAN_TAG))
834 OP_IMM3(ARM_AND, r_A, r_A, VLAN_VID_MASK, ctx);
835 else
836 OP_IMM3(ARM_AND, r_A, r_A, VLAN_TAG_PRESENT, ctx);
837 break;
838 case BPF_ANC | SKF_AD_QUEUE:
839 ctx->seen |= SEEN_SKB;
840 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
841 queue_mapping) != 2);
842 BUILD_BUG_ON(offsetof(struct sk_buff,
843 queue_mapping) > 0xff);
844 off = offsetof(struct sk_buff, queue_mapping);
845 emit(ARM_LDRH_I(r_A, r_skb, off), ctx);
846 break;
847 default:
848 return -1;
849 }
850 }
851
852 /* compute offsets only during the first pass */
853 if (ctx->target == NULL)
854 ctx->offsets[i] = ctx->idx * 4;
855
856 return 0;
857 }
858
859
860 void bpf_jit_compile(struct bpf_prog *fp)
861 {
862 struct jit_ctx ctx;
863 unsigned tmp_idx;
864 unsigned alloc_size;
865
866 if (!bpf_jit_enable)
867 return;
868
869 memset(&ctx, 0, sizeof(ctx));
870 ctx.skf = fp;
871 ctx.ret0_fp_idx = -1;
872
873 ctx.offsets = kzalloc(4 * (ctx.skf->len + 1), GFP_KERNEL);
874 if (ctx.offsets == NULL)
875 return;
876
877 /* fake pass to fill in the ctx->seen */
878 if (unlikely(build_body(&ctx)))
879 goto out;
880
881 tmp_idx = ctx.idx;
882 build_prologue(&ctx);
883 ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4;
884
885 #if __LINUX_ARM_ARCH__ < 7
886 tmp_idx = ctx.idx;
887 build_epilogue(&ctx);
888 ctx.epilogue_bytes = (ctx.idx - tmp_idx) * 4;
889
890 ctx.idx += ctx.imm_count;
891 if (ctx.imm_count) {
892 ctx.imms = kzalloc(4 * ctx.imm_count, GFP_KERNEL);
893 if (ctx.imms == NULL)
894 goto out;
895 }
896 #else
897 /* there's nothing after the epilogue on ARMv7 */
898 build_epilogue(&ctx);
899 #endif
900
901 alloc_size = 4 * ctx.idx;
902 ctx.target = module_alloc(alloc_size);
903 if (unlikely(ctx.target == NULL))
904 goto out;
905
906 ctx.idx = 0;
907 build_prologue(&ctx);
908 build_body(&ctx);
909 build_epilogue(&ctx);
910
911 flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx));
912
913 #if __LINUX_ARM_ARCH__ < 7
914 if (ctx.imm_count)
915 kfree(ctx.imms);
916 #endif
917
918 if (bpf_jit_enable > 1)
919 /* there are 2 passes here */
920 bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
921
922 fp->bpf_func = (void *)ctx.target;
923 fp->jited = 1;
924 out:
925 kfree(ctx.offsets);
926 return;
927 }
928
929 void bpf_jit_free(struct bpf_prog *fp)
930 {
931 if (fp->jited)
932 module_free(NULL, fp->bpf_func);
933
934 bpf_prog_unlock_free(fp);
935 }
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