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arm64: bpf: fix endianness conversion bugs
[deliverable/linux.git] / arch / arm64 / net / bpf_jit_comp.c
1 /*
2 * BPF JIT compiler for ARM64
3 *
4 * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18
19 #define pr_fmt(fmt) "bpf_jit: " fmt
20
21 #include <linux/filter.h>
22 #include <linux/printk.h>
23 #include <linux/skbuff.h>
24 #include <linux/slab.h>
25
26 #include <asm/byteorder.h>
27 #include <asm/cacheflush.h>
28 #include <asm/debug-monitors.h>
29
30 #include "bpf_jit.h"
31
32 int bpf_jit_enable __read_mostly;
33
34 #define TMP_REG_1 (MAX_BPF_REG + 0)
35 #define TMP_REG_2 (MAX_BPF_REG + 1)
36
37 /* Map BPF registers to A64 registers */
38 static const int bpf2a64[] = {
39 /* return value from in-kernel function, and exit value from eBPF */
40 [BPF_REG_0] = A64_R(7),
41 /* arguments from eBPF program to in-kernel function */
42 [BPF_REG_1] = A64_R(0),
43 [BPF_REG_2] = A64_R(1),
44 [BPF_REG_3] = A64_R(2),
45 [BPF_REG_4] = A64_R(3),
46 [BPF_REG_5] = A64_R(4),
47 /* callee saved registers that in-kernel function will preserve */
48 [BPF_REG_6] = A64_R(19),
49 [BPF_REG_7] = A64_R(20),
50 [BPF_REG_8] = A64_R(21),
51 [BPF_REG_9] = A64_R(22),
52 /* read-only frame pointer to access stack */
53 [BPF_REG_FP] = A64_FP,
54 /* temporary register for internal BPF JIT */
55 [TMP_REG_1] = A64_R(23),
56 [TMP_REG_2] = A64_R(24),
57 };
58
59 struct jit_ctx {
60 const struct bpf_prog *prog;
61 int idx;
62 int tmp_used;
63 int epilogue_offset;
64 int *offset;
65 u32 *image;
66 };
67
68 static inline void emit(const u32 insn, struct jit_ctx *ctx)
69 {
70 if (ctx->image != NULL)
71 ctx->image[ctx->idx] = cpu_to_le32(insn);
72
73 ctx->idx++;
74 }
75
76 static inline void emit_a64_mov_i64(const int reg, const u64 val,
77 struct jit_ctx *ctx)
78 {
79 u64 tmp = val;
80 int shift = 0;
81
82 emit(A64_MOVZ(1, reg, tmp & 0xffff, shift), ctx);
83 tmp >>= 16;
84 shift += 16;
85 while (tmp) {
86 if (tmp & 0xffff)
87 emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx);
88 tmp >>= 16;
89 shift += 16;
90 }
91 }
92
93 static inline void emit_a64_mov_i(const int is64, const int reg,
94 const s32 val, struct jit_ctx *ctx)
95 {
96 u16 hi = val >> 16;
97 u16 lo = val & 0xffff;
98
99 if (hi & 0x8000) {
100 if (hi == 0xffff) {
101 emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx);
102 } else {
103 emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx);
104 emit(A64_MOVK(is64, reg, lo, 0), ctx);
105 }
106 } else {
107 emit(A64_MOVZ(is64, reg, lo, 0), ctx);
108 if (hi)
109 emit(A64_MOVK(is64, reg, hi, 16), ctx);
110 }
111 }
112
113 static inline int bpf2a64_offset(int bpf_to, int bpf_from,
114 const struct jit_ctx *ctx)
115 {
116 int to = ctx->offset[bpf_to];
117 /* -1 to account for the Branch instruction */
118 int from = ctx->offset[bpf_from] - 1;
119
120 return to - from;
121 }
122
123 static void jit_fill_hole(void *area, unsigned int size)
124 {
125 u32 *ptr;
126 /* We are guaranteed to have aligned memory. */
127 for (ptr = area; size >= sizeof(u32); size -= sizeof(u32))
128 *ptr++ = cpu_to_le32(AARCH64_BREAK_FAULT);
129 }
130
131 static inline int epilogue_offset(const struct jit_ctx *ctx)
132 {
133 int to = ctx->epilogue_offset;
134 int from = ctx->idx;
135
136 return to - from;
137 }
138
139 /* Stack must be multiples of 16B */
140 #define STACK_ALIGN(sz) (((sz) + 15) & ~15)
141
142 static void build_prologue(struct jit_ctx *ctx)
143 {
144 const u8 r6 = bpf2a64[BPF_REG_6];
145 const u8 r7 = bpf2a64[BPF_REG_7];
146 const u8 r8 = bpf2a64[BPF_REG_8];
147 const u8 r9 = bpf2a64[BPF_REG_9];
148 const u8 fp = bpf2a64[BPF_REG_FP];
149 const u8 ra = bpf2a64[BPF_REG_A];
150 const u8 rx = bpf2a64[BPF_REG_X];
151 const u8 tmp1 = bpf2a64[TMP_REG_1];
152 const u8 tmp2 = bpf2a64[TMP_REG_2];
153 int stack_size = MAX_BPF_STACK;
154
155 stack_size += 4; /* extra for skb_copy_bits buffer */
156 stack_size = STACK_ALIGN(stack_size);
157
158 /* Save callee-saved register */
159 emit(A64_PUSH(r6, r7, A64_SP), ctx);
160 emit(A64_PUSH(r8, r9, A64_SP), ctx);
161 if (ctx->tmp_used)
162 emit(A64_PUSH(tmp1, tmp2, A64_SP), ctx);
163
164 /* Set up BPF stack */
165 emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
166
167 /* Set up frame pointer */
168 emit(A64_MOV(1, fp, A64_SP), ctx);
169
170 /* Clear registers A and X */
171 emit_a64_mov_i64(ra, 0, ctx);
172 emit_a64_mov_i64(rx, 0, ctx);
173 }
174
175 static void build_epilogue(struct jit_ctx *ctx)
176 {
177 const u8 r0 = bpf2a64[BPF_REG_0];
178 const u8 r6 = bpf2a64[BPF_REG_6];
179 const u8 r7 = bpf2a64[BPF_REG_7];
180 const u8 r8 = bpf2a64[BPF_REG_8];
181 const u8 r9 = bpf2a64[BPF_REG_9];
182 const u8 fp = bpf2a64[BPF_REG_FP];
183 const u8 tmp1 = bpf2a64[TMP_REG_1];
184 const u8 tmp2 = bpf2a64[TMP_REG_2];
185 int stack_size = MAX_BPF_STACK;
186
187 stack_size += 4; /* extra for skb_copy_bits buffer */
188 stack_size = STACK_ALIGN(stack_size);
189
190 /* We're done with BPF stack */
191 emit(A64_ADD_I(1, A64_SP, A64_SP, stack_size), ctx);
192
193 /* Restore callee-saved register */
194 if (ctx->tmp_used)
195 emit(A64_POP(tmp1, tmp2, A64_SP), ctx);
196 emit(A64_POP(r8, r9, A64_SP), ctx);
197 emit(A64_POP(r6, r7, A64_SP), ctx);
198
199 /* Restore frame pointer */
200 emit(A64_MOV(1, fp, A64_SP), ctx);
201
202 /* Set return value */
203 emit(A64_MOV(1, A64_R(0), r0), ctx);
204
205 emit(A64_RET(A64_LR), ctx);
206 }
207
208 /* JITs an eBPF instruction.
209 * Returns:
210 * 0 - successfully JITed an 8-byte eBPF instruction.
211 * >0 - successfully JITed a 16-byte eBPF instruction.
212 * <0 - failed to JIT.
213 */
214 static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
215 {
216 const u8 code = insn->code;
217 const u8 dst = bpf2a64[insn->dst_reg];
218 const u8 src = bpf2a64[insn->src_reg];
219 const u8 tmp = bpf2a64[TMP_REG_1];
220 const u8 tmp2 = bpf2a64[TMP_REG_2];
221 const s16 off = insn->off;
222 const s32 imm = insn->imm;
223 const int i = insn - ctx->prog->insnsi;
224 const bool is64 = BPF_CLASS(code) == BPF_ALU64;
225 u8 jmp_cond;
226 s32 jmp_offset;
227
228 switch (code) {
229 /* dst = src */
230 case BPF_ALU | BPF_MOV | BPF_X:
231 case BPF_ALU64 | BPF_MOV | BPF_X:
232 emit(A64_MOV(is64, dst, src), ctx);
233 break;
234 /* dst = dst OP src */
235 case BPF_ALU | BPF_ADD | BPF_X:
236 case BPF_ALU64 | BPF_ADD | BPF_X:
237 emit(A64_ADD(is64, dst, dst, src), ctx);
238 break;
239 case BPF_ALU | BPF_SUB | BPF_X:
240 case BPF_ALU64 | BPF_SUB | BPF_X:
241 emit(A64_SUB(is64, dst, dst, src), ctx);
242 break;
243 case BPF_ALU | BPF_AND | BPF_X:
244 case BPF_ALU64 | BPF_AND | BPF_X:
245 emit(A64_AND(is64, dst, dst, src), ctx);
246 break;
247 case BPF_ALU | BPF_OR | BPF_X:
248 case BPF_ALU64 | BPF_OR | BPF_X:
249 emit(A64_ORR(is64, dst, dst, src), ctx);
250 break;
251 case BPF_ALU | BPF_XOR | BPF_X:
252 case BPF_ALU64 | BPF_XOR | BPF_X:
253 emit(A64_EOR(is64, dst, dst, src), ctx);
254 break;
255 case BPF_ALU | BPF_MUL | BPF_X:
256 case BPF_ALU64 | BPF_MUL | BPF_X:
257 emit(A64_MUL(is64, dst, dst, src), ctx);
258 break;
259 case BPF_ALU | BPF_DIV | BPF_X:
260 case BPF_ALU64 | BPF_DIV | BPF_X:
261 emit(A64_UDIV(is64, dst, dst, src), ctx);
262 break;
263 case BPF_ALU | BPF_MOD | BPF_X:
264 case BPF_ALU64 | BPF_MOD | BPF_X:
265 ctx->tmp_used = 1;
266 emit(A64_UDIV(is64, tmp, dst, src), ctx);
267 emit(A64_MUL(is64, tmp, tmp, src), ctx);
268 emit(A64_SUB(is64, dst, dst, tmp), ctx);
269 break;
270 case BPF_ALU | BPF_LSH | BPF_X:
271 case BPF_ALU64 | BPF_LSH | BPF_X:
272 emit(A64_LSLV(is64, dst, dst, src), ctx);
273 break;
274 case BPF_ALU | BPF_RSH | BPF_X:
275 case BPF_ALU64 | BPF_RSH | BPF_X:
276 emit(A64_LSRV(is64, dst, dst, src), ctx);
277 break;
278 case BPF_ALU | BPF_ARSH | BPF_X:
279 case BPF_ALU64 | BPF_ARSH | BPF_X:
280 emit(A64_ASRV(is64, dst, dst, src), ctx);
281 break;
282 /* dst = -dst */
283 case BPF_ALU | BPF_NEG:
284 case BPF_ALU64 | BPF_NEG:
285 emit(A64_NEG(is64, dst, dst), ctx);
286 break;
287 /* dst = BSWAP##imm(dst) */
288 case BPF_ALU | BPF_END | BPF_FROM_LE:
289 case BPF_ALU | BPF_END | BPF_FROM_BE:
290 #ifdef CONFIG_CPU_BIG_ENDIAN
291 if (BPF_SRC(code) == BPF_FROM_BE)
292 goto emit_bswap_uxt;
293 #else /* !CONFIG_CPU_BIG_ENDIAN */
294 if (BPF_SRC(code) == BPF_FROM_LE)
295 goto emit_bswap_uxt;
296 #endif
297 switch (imm) {
298 case 16:
299 emit(A64_REV16(is64, dst, dst), ctx);
300 /* zero-extend 16 bits into 64 bits */
301 emit(A64_UXTH(is64, dst, dst), ctx);
302 break;
303 case 32:
304 emit(A64_REV32(is64, dst, dst), ctx);
305 /* upper 32 bits already cleared */
306 break;
307 case 64:
308 emit(A64_REV64(dst, dst), ctx);
309 break;
310 }
311 break;
312 emit_bswap_uxt:
313 switch (imm) {
314 case 16:
315 /* zero-extend 16 bits into 64 bits */
316 emit(A64_UXTH(is64, dst, dst), ctx);
317 break;
318 case 32:
319 /* zero-extend 32 bits into 64 bits */
320 emit(A64_UXTW(is64, dst, dst), ctx);
321 break;
322 case 64:
323 /* nop */
324 break;
325 }
326 break;
327 /* dst = imm */
328 case BPF_ALU | BPF_MOV | BPF_K:
329 case BPF_ALU64 | BPF_MOV | BPF_K:
330 emit_a64_mov_i(is64, dst, imm, ctx);
331 break;
332 /* dst = dst OP imm */
333 case BPF_ALU | BPF_ADD | BPF_K:
334 case BPF_ALU64 | BPF_ADD | BPF_K:
335 ctx->tmp_used = 1;
336 emit_a64_mov_i(is64, tmp, imm, ctx);
337 emit(A64_ADD(is64, dst, dst, tmp), ctx);
338 break;
339 case BPF_ALU | BPF_SUB | BPF_K:
340 case BPF_ALU64 | BPF_SUB | BPF_K:
341 ctx->tmp_used = 1;
342 emit_a64_mov_i(is64, tmp, imm, ctx);
343 emit(A64_SUB(is64, dst, dst, tmp), ctx);
344 break;
345 case BPF_ALU | BPF_AND | BPF_K:
346 case BPF_ALU64 | BPF_AND | BPF_K:
347 ctx->tmp_used = 1;
348 emit_a64_mov_i(is64, tmp, imm, ctx);
349 emit(A64_AND(is64, dst, dst, tmp), ctx);
350 break;
351 case BPF_ALU | BPF_OR | BPF_K:
352 case BPF_ALU64 | BPF_OR | BPF_K:
353 ctx->tmp_used = 1;
354 emit_a64_mov_i(is64, tmp, imm, ctx);
355 emit(A64_ORR(is64, dst, dst, tmp), ctx);
356 break;
357 case BPF_ALU | BPF_XOR | BPF_K:
358 case BPF_ALU64 | BPF_XOR | BPF_K:
359 ctx->tmp_used = 1;
360 emit_a64_mov_i(is64, tmp, imm, ctx);
361 emit(A64_EOR(is64, dst, dst, tmp), ctx);
362 break;
363 case BPF_ALU | BPF_MUL | BPF_K:
364 case BPF_ALU64 | BPF_MUL | BPF_K:
365 ctx->tmp_used = 1;
366 emit_a64_mov_i(is64, tmp, imm, ctx);
367 emit(A64_MUL(is64, dst, dst, tmp), ctx);
368 break;
369 case BPF_ALU | BPF_DIV | BPF_K:
370 case BPF_ALU64 | BPF_DIV | BPF_K:
371 ctx->tmp_used = 1;
372 emit_a64_mov_i(is64, tmp, imm, ctx);
373 emit(A64_UDIV(is64, dst, dst, tmp), ctx);
374 break;
375 case BPF_ALU | BPF_MOD | BPF_K:
376 case BPF_ALU64 | BPF_MOD | BPF_K:
377 ctx->tmp_used = 1;
378 emit_a64_mov_i(is64, tmp2, imm, ctx);
379 emit(A64_UDIV(is64, tmp, dst, tmp2), ctx);
380 emit(A64_MUL(is64, tmp, tmp, tmp2), ctx);
381 emit(A64_SUB(is64, dst, dst, tmp), ctx);
382 break;
383 case BPF_ALU | BPF_LSH | BPF_K:
384 case BPF_ALU64 | BPF_LSH | BPF_K:
385 emit(A64_LSL(is64, dst, dst, imm), ctx);
386 break;
387 case BPF_ALU | BPF_RSH | BPF_K:
388 case BPF_ALU64 | BPF_RSH | BPF_K:
389 emit(A64_LSR(is64, dst, dst, imm), ctx);
390 break;
391 case BPF_ALU | BPF_ARSH | BPF_K:
392 case BPF_ALU64 | BPF_ARSH | BPF_K:
393 emit(A64_ASR(is64, dst, dst, imm), ctx);
394 break;
395
396 #define check_imm(bits, imm) do { \
397 if ((((imm) > 0) && ((imm) >> (bits))) || \
398 (((imm) < 0) && (~(imm) >> (bits)))) { \
399 pr_info("[%2d] imm=%d(0x%x) out of range\n", \
400 i, imm, imm); \
401 return -EINVAL; \
402 } \
403 } while (0)
404 #define check_imm19(imm) check_imm(19, imm)
405 #define check_imm26(imm) check_imm(26, imm)
406
407 /* JUMP off */
408 case BPF_JMP | BPF_JA:
409 jmp_offset = bpf2a64_offset(i + off, i, ctx);
410 check_imm26(jmp_offset);
411 emit(A64_B(jmp_offset), ctx);
412 break;
413 /* IF (dst COND src) JUMP off */
414 case BPF_JMP | BPF_JEQ | BPF_X:
415 case BPF_JMP | BPF_JGT | BPF_X:
416 case BPF_JMP | BPF_JGE | BPF_X:
417 case BPF_JMP | BPF_JNE | BPF_X:
418 case BPF_JMP | BPF_JSGT | BPF_X:
419 case BPF_JMP | BPF_JSGE | BPF_X:
420 emit(A64_CMP(1, dst, src), ctx);
421 emit_cond_jmp:
422 jmp_offset = bpf2a64_offset(i + off, i, ctx);
423 check_imm19(jmp_offset);
424 switch (BPF_OP(code)) {
425 case BPF_JEQ:
426 jmp_cond = A64_COND_EQ;
427 break;
428 case BPF_JGT:
429 jmp_cond = A64_COND_HI;
430 break;
431 case BPF_JGE:
432 jmp_cond = A64_COND_CS;
433 break;
434 case BPF_JNE:
435 jmp_cond = A64_COND_NE;
436 break;
437 case BPF_JSGT:
438 jmp_cond = A64_COND_GT;
439 break;
440 case BPF_JSGE:
441 jmp_cond = A64_COND_GE;
442 break;
443 default:
444 return -EFAULT;
445 }
446 emit(A64_B_(jmp_cond, jmp_offset), ctx);
447 break;
448 case BPF_JMP | BPF_JSET | BPF_X:
449 emit(A64_TST(1, dst, src), ctx);
450 goto emit_cond_jmp;
451 /* IF (dst COND imm) JUMP off */
452 case BPF_JMP | BPF_JEQ | BPF_K:
453 case BPF_JMP | BPF_JGT | BPF_K:
454 case BPF_JMP | BPF_JGE | BPF_K:
455 case BPF_JMP | BPF_JNE | BPF_K:
456 case BPF_JMP | BPF_JSGT | BPF_K:
457 case BPF_JMP | BPF_JSGE | BPF_K:
458 ctx->tmp_used = 1;
459 emit_a64_mov_i(1, tmp, imm, ctx);
460 emit(A64_CMP(1, dst, tmp), ctx);
461 goto emit_cond_jmp;
462 case BPF_JMP | BPF_JSET | BPF_K:
463 ctx->tmp_used = 1;
464 emit_a64_mov_i(1, tmp, imm, ctx);
465 emit(A64_TST(1, dst, tmp), ctx);
466 goto emit_cond_jmp;
467 /* function call */
468 case BPF_JMP | BPF_CALL:
469 {
470 const u8 r0 = bpf2a64[BPF_REG_0];
471 const u64 func = (u64)__bpf_call_base + imm;
472
473 ctx->tmp_used = 1;
474 emit_a64_mov_i64(tmp, func, ctx);
475 emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
476 emit(A64_MOV(1, A64_FP, A64_SP), ctx);
477 emit(A64_BLR(tmp), ctx);
478 emit(A64_MOV(1, r0, A64_R(0)), ctx);
479 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
480 break;
481 }
482 /* function return */
483 case BPF_JMP | BPF_EXIT:
484 /* Optimization: when last instruction is EXIT,
485 simply fallthrough to epilogue. */
486 if (i == ctx->prog->len - 1)
487 break;
488 jmp_offset = epilogue_offset(ctx);
489 check_imm26(jmp_offset);
490 emit(A64_B(jmp_offset), ctx);
491 break;
492
493 /* dst = imm64 */
494 case BPF_LD | BPF_IMM | BPF_DW:
495 {
496 const struct bpf_insn insn1 = insn[1];
497 u64 imm64;
498
499 if (insn1.code != 0 || insn1.src_reg != 0 ||
500 insn1.dst_reg != 0 || insn1.off != 0) {
501 /* Note: verifier in BPF core must catch invalid
502 * instructions.
503 */
504 pr_err_once("Invalid BPF_LD_IMM64 instruction\n");
505 return -EINVAL;
506 }
507
508 imm64 = (u64)insn1.imm << 32 | (u32)imm;
509 emit_a64_mov_i64(dst, imm64, ctx);
510
511 return 1;
512 }
513
514 /* LDX: dst = *(size *)(src + off) */
515 case BPF_LDX | BPF_MEM | BPF_W:
516 case BPF_LDX | BPF_MEM | BPF_H:
517 case BPF_LDX | BPF_MEM | BPF_B:
518 case BPF_LDX | BPF_MEM | BPF_DW:
519 ctx->tmp_used = 1;
520 emit_a64_mov_i(1, tmp, off, ctx);
521 switch (BPF_SIZE(code)) {
522 case BPF_W:
523 emit(A64_LDR32(dst, src, tmp), ctx);
524 break;
525 case BPF_H:
526 emit(A64_LDRH(dst, src, tmp), ctx);
527 break;
528 case BPF_B:
529 emit(A64_LDRB(dst, src, tmp), ctx);
530 break;
531 case BPF_DW:
532 emit(A64_LDR64(dst, src, tmp), ctx);
533 break;
534 }
535 break;
536
537 /* ST: *(size *)(dst + off) = imm */
538 case BPF_ST | BPF_MEM | BPF_W:
539 case BPF_ST | BPF_MEM | BPF_H:
540 case BPF_ST | BPF_MEM | BPF_B:
541 case BPF_ST | BPF_MEM | BPF_DW:
542 goto notyet;
543
544 /* STX: *(size *)(dst + off) = src */
545 case BPF_STX | BPF_MEM | BPF_W:
546 case BPF_STX | BPF_MEM | BPF_H:
547 case BPF_STX | BPF_MEM | BPF_B:
548 case BPF_STX | BPF_MEM | BPF_DW:
549 ctx->tmp_used = 1;
550 emit_a64_mov_i(1, tmp, off, ctx);
551 switch (BPF_SIZE(code)) {
552 case BPF_W:
553 emit(A64_STR32(src, dst, tmp), ctx);
554 break;
555 case BPF_H:
556 emit(A64_STRH(src, dst, tmp), ctx);
557 break;
558 case BPF_B:
559 emit(A64_STRB(src, dst, tmp), ctx);
560 break;
561 case BPF_DW:
562 emit(A64_STR64(src, dst, tmp), ctx);
563 break;
564 }
565 break;
566 /* STX XADD: lock *(u32 *)(dst + off) += src */
567 case BPF_STX | BPF_XADD | BPF_W:
568 /* STX XADD: lock *(u64 *)(dst + off) += src */
569 case BPF_STX | BPF_XADD | BPF_DW:
570 goto notyet;
571
572 /* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + imm)) */
573 case BPF_LD | BPF_ABS | BPF_W:
574 case BPF_LD | BPF_ABS | BPF_H:
575 case BPF_LD | BPF_ABS | BPF_B:
576 /* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + src + imm)) */
577 case BPF_LD | BPF_IND | BPF_W:
578 case BPF_LD | BPF_IND | BPF_H:
579 case BPF_LD | BPF_IND | BPF_B:
580 {
581 const u8 r0 = bpf2a64[BPF_REG_0]; /* r0 = return value */
582 const u8 r6 = bpf2a64[BPF_REG_6]; /* r6 = pointer to sk_buff */
583 const u8 fp = bpf2a64[BPF_REG_FP];
584 const u8 r1 = bpf2a64[BPF_REG_1]; /* r1: struct sk_buff *skb */
585 const u8 r2 = bpf2a64[BPF_REG_2]; /* r2: int k */
586 const u8 r3 = bpf2a64[BPF_REG_3]; /* r3: unsigned int size */
587 const u8 r4 = bpf2a64[BPF_REG_4]; /* r4: void *buffer */
588 const u8 r5 = bpf2a64[BPF_REG_5]; /* r5: void *(*func)(...) */
589 int size;
590
591 emit(A64_MOV(1, r1, r6), ctx);
592 emit_a64_mov_i(0, r2, imm, ctx);
593 if (BPF_MODE(code) == BPF_IND)
594 emit(A64_ADD(0, r2, r2, src), ctx);
595 switch (BPF_SIZE(code)) {
596 case BPF_W:
597 size = 4;
598 break;
599 case BPF_H:
600 size = 2;
601 break;
602 case BPF_B:
603 size = 1;
604 break;
605 default:
606 return -EINVAL;
607 }
608 emit_a64_mov_i64(r3, size, ctx);
609 emit(A64_ADD_I(1, r4, fp, MAX_BPF_STACK), ctx);
610 emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx);
611 emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
612 emit(A64_MOV(1, A64_FP, A64_SP), ctx);
613 emit(A64_BLR(r5), ctx);
614 emit(A64_MOV(1, r0, A64_R(0)), ctx);
615 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
616
617 jmp_offset = epilogue_offset(ctx);
618 check_imm19(jmp_offset);
619 emit(A64_CBZ(1, r0, jmp_offset), ctx);
620 emit(A64_MOV(1, r5, r0), ctx);
621 switch (BPF_SIZE(code)) {
622 case BPF_W:
623 emit(A64_LDR32(r0, r5, A64_ZR), ctx);
624 #ifndef CONFIG_CPU_BIG_ENDIAN
625 emit(A64_REV32(0, r0, r0), ctx);
626 #endif
627 break;
628 case BPF_H:
629 emit(A64_LDRH(r0, r5, A64_ZR), ctx);
630 #ifndef CONFIG_CPU_BIG_ENDIAN
631 emit(A64_REV16(0, r0, r0), ctx);
632 #endif
633 break;
634 case BPF_B:
635 emit(A64_LDRB(r0, r5, A64_ZR), ctx);
636 break;
637 }
638 break;
639 }
640 notyet:
641 pr_info_once("*** NOT YET: opcode %02x ***\n", code);
642 return -EFAULT;
643
644 default:
645 pr_err_once("unknown opcode %02x\n", code);
646 return -EINVAL;
647 }
648
649 return 0;
650 }
651
652 static int build_body(struct jit_ctx *ctx)
653 {
654 const struct bpf_prog *prog = ctx->prog;
655 int i;
656
657 for (i = 0; i < prog->len; i++) {
658 const struct bpf_insn *insn = &prog->insnsi[i];
659 int ret;
660
661 ret = build_insn(insn, ctx);
662
663 if (ctx->image == NULL)
664 ctx->offset[i] = ctx->idx;
665
666 if (ret > 0) {
667 i++;
668 continue;
669 }
670 if (ret)
671 return ret;
672 }
673
674 return 0;
675 }
676
677 static inline void bpf_flush_icache(void *start, void *end)
678 {
679 flush_icache_range((unsigned long)start, (unsigned long)end);
680 }
681
682 void bpf_jit_compile(struct bpf_prog *prog)
683 {
684 /* Nothing to do here. We support Internal BPF. */
685 }
686
687 void bpf_int_jit_compile(struct bpf_prog *prog)
688 {
689 struct bpf_binary_header *header;
690 struct jit_ctx ctx;
691 int image_size;
692 u8 *image_ptr;
693
694 if (!bpf_jit_enable)
695 return;
696
697 if (!prog || !prog->len)
698 return;
699
700 memset(&ctx, 0, sizeof(ctx));
701 ctx.prog = prog;
702
703 ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL);
704 if (ctx.offset == NULL)
705 return;
706
707 /* 1. Initial fake pass to compute ctx->idx. */
708
709 /* Fake pass to fill in ctx->offset and ctx->tmp_used. */
710 if (build_body(&ctx))
711 goto out;
712
713 build_prologue(&ctx);
714
715 ctx.epilogue_offset = ctx.idx;
716 build_epilogue(&ctx);
717
718 /* Now we know the actual image size. */
719 image_size = sizeof(u32) * ctx.idx;
720 header = bpf_jit_binary_alloc(image_size, &image_ptr,
721 sizeof(u32), jit_fill_hole);
722 if (header == NULL)
723 goto out;
724
725 /* 2. Now, the actual pass. */
726
727 ctx.image = (u32 *)image_ptr;
728 ctx.idx = 0;
729
730 build_prologue(&ctx);
731
732 if (build_body(&ctx)) {
733 bpf_jit_binary_free(header);
734 goto out;
735 }
736
737 build_epilogue(&ctx);
738
739 /* And we're done. */
740 if (bpf_jit_enable > 1)
741 bpf_jit_dump(prog->len, image_size, 2, ctx.image);
742
743 bpf_flush_icache(ctx.image, ctx.image + ctx.idx);
744
745 set_memory_ro((unsigned long)header, header->pages);
746 prog->bpf_func = (void *)ctx.image;
747 prog->jited = true;
748 out:
749 kfree(ctx.offset);
750 }
751
752 void bpf_jit_free(struct bpf_prog *prog)
753 {
754 unsigned long addr = (unsigned long)prog->bpf_func & PAGE_MASK;
755 struct bpf_binary_header *header = (void *)addr;
756
757 if (!prog->jited)
758 goto free_filter;
759
760 set_memory_rw(addr, header->pages);
761 bpf_jit_binary_free(header);
762
763 free_filter:
764 bpf_prog_unlock_free(prog);
765 }
Linux kernel - Deliverables
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