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1/* bpf_jit_comp.c : BPF JIT compiler
2 *
3 * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com)
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; version 2
8 * of the License.
9 */
10#include <linux/moduleloader.h>
11#include <asm/cacheflush.h>
12#include <linux/netdevice.h>
13#include <linux/filter.h>
14#include <linux/if_vlan.h>
15#include <linux/random.h>
16
17/*
18 * Conventions :
19 * EAX : BPF A accumulator
20 * EBX : BPF X accumulator
21 * RDI : pointer to skb (first argument given to JIT function)
22 * RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
23 * ECX,EDX,ESI : scratch registers
24 * r9d : skb->len - skb->data_len (headlen)
25 * r8 : skb->data
26 * -8(RBP) : saved RBX value
27 * -16(RBP)..-80(RBP) : BPF_MEMWORDS values
28 */
29int bpf_jit_enable __read_mostly;
30
31/*
32 * assembly code in arch/x86/net/bpf_jit.S
33 */
34extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
35extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[];
36extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[];
37extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
38extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[];
39
40static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
41{
42 if (len == 1)
43 *ptr = bytes;
44 else if (len == 2)
45 *(u16 *)ptr = bytes;
46 else {
47 *(u32 *)ptr = bytes;
48 barrier();
49 }
50 return ptr + len;
51}
52
53#define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0)
54
55#define EMIT1(b1) EMIT(b1, 1)
56#define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
57#define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
58#define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
59#define EMIT1_off32(b1, off) do { EMIT1(b1); EMIT(off, 4);} while (0)
60
61#define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
62#define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
63
64static inline bool is_imm8(int value)
65{
66 return value <= 127 && value >= -128;
67}
68
69static inline bool is_near(int offset)
70{
71 return offset <= 127 && offset >= -128;
72}
73
74#define EMIT_JMP(offset) \
75do { \
76 if (offset) { \
77 if (is_near(offset)) \
78 EMIT2(0xeb, offset); /* jmp .+off8 */ \
79 else \
80 EMIT1_off32(0xe9, offset); /* jmp .+off32 */ \
81 } \
82} while (0)
83
84/* list of x86 cond jumps opcodes (. + s8)
85 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
86 */
87#define X86_JB 0x72
88#define X86_JAE 0x73
89#define X86_JE 0x74
90#define X86_JNE 0x75
91#define X86_JBE 0x76
92#define X86_JA 0x77
93
94#define EMIT_COND_JMP(op, offset) \
95do { \
96 if (is_near(offset)) \
97 EMIT2(op, offset); /* jxx .+off8 */ \
98 else { \
99 EMIT2(0x0f, op + 0x10); \
100 EMIT(offset, 4); /* jxx .+off32 */ \
101 } \
102} while (0)
103
104#define COND_SEL(CODE, TOP, FOP) \
105 case CODE: \
106 t_op = TOP; \
107 f_op = FOP; \
108 goto cond_branch
109
110
111#define SEEN_DATAREF 1 /* might call external helpers */
112#define SEEN_XREG 2 /* ebx is used */
113#define SEEN_MEM 4 /* use mem[] for temporary storage */
114
115static inline void bpf_flush_icache(void *start, void *end)
116{
117 mm_segment_t old_fs = get_fs();
118
119 set_fs(KERNEL_DS);
120 smp_wmb();
121 flush_icache_range((unsigned long)start, (unsigned long)end);
122 set_fs(old_fs);
123}
124
125#define CHOOSE_LOAD_FUNC(K, func) \
126 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
127
128/* Helper to find the offset of pkt_type in sk_buff
129 * We want to make sure its still a 3bit field starting at a byte boundary.
130 */
131#define PKT_TYPE_MAX 7
132static int pkt_type_offset(void)
133{
134 struct sk_buff skb_probe = {
135 .pkt_type = ~0,
136 };
137 char *ct = (char *)&skb_probe;
138 unsigned int off;
139
140 for (off = 0; off < sizeof(struct sk_buff); off++) {
141 if (ct[off] == PKT_TYPE_MAX)
142 return off;
143 }
144 pr_err_once("Please fix pkt_type_offset(), as pkt_type couldn't be found\n");
145 return -1;
146}
147
148struct bpf_binary_header {
149 unsigned int pages;
150 /* Note : for security reasons, bpf code will follow a randomly
151 * sized amount of int3 instructions
152 */
153 u8 image[];
154};
155
156static struct bpf_binary_header *bpf_alloc_binary(unsigned int proglen,
157 u8 **image_ptr)
158{
159 unsigned int sz, hole;
160 struct bpf_binary_header *header;
161
162 /* Most of BPF filters are really small,
163 * but if some of them fill a page, allow at least
164 * 128 extra bytes to insert a random section of int3
165 */
166 sz = round_up(proglen + sizeof(*header) + 128, PAGE_SIZE);
167 header = module_alloc(sz);
168 if (!header)
169 return NULL;
170
171 memset(header, 0xcc, sz); /* fill whole space with int3 instructions */
172
173 header->pages = sz / PAGE_SIZE;
174 hole = min(sz - (proglen + sizeof(*header)), PAGE_SIZE - sizeof(*header));
175
176 /* insert a random number of int3 instructions before BPF code */
177 *image_ptr = &header->image[prandom_u32() % hole];
178 return header;
179}
180
181void bpf_jit_compile(struct sk_filter *fp)
182{
183 u8 temp[64];
184 u8 *prog;
185 unsigned int proglen, oldproglen = 0;
186 int ilen, i;
187 int t_offset, f_offset;
188 u8 t_op, f_op, seen = 0, pass;
189 u8 *image = NULL;
190 struct bpf_binary_header *header = NULL;
191 u8 *func;
192 int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
193 unsigned int cleanup_addr; /* epilogue code offset */
194 unsigned int *addrs;
195 const struct sock_filter *filter = fp->insns;
196 int flen = fp->len;
197
198 if (!bpf_jit_enable)
199 return;
200
201 addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
202 if (addrs == NULL)
203 return;
204
205 /* Before first pass, make a rough estimation of addrs[]
206 * each bpf instruction is translated to less than 64 bytes
207 */
208 for (proglen = 0, i = 0; i < flen; i++) {
209 proglen += 64;
210 addrs[i] = proglen;
211 }
212 cleanup_addr = proglen; /* epilogue address */
213
214 for (pass = 0; pass < 10; pass++) {
215 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
216 /* no prologue/epilogue for trivial filters (RET something) */
217 proglen = 0;
218 prog = temp;
219
220 if (seen_or_pass0) {
221 EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
222 EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */
223 /* note : must save %rbx in case bpf_error is hit */
224 if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
225 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
226 if (seen_or_pass0 & SEEN_XREG)
227 CLEAR_X(); /* make sure we dont leek kernel memory */
228
229 /*
230 * If this filter needs to access skb data,
231 * loads r9 and r8 with :
232 * r9 = skb->len - skb->data_len
233 * r8 = skb->data
234 */
235 if (seen_or_pass0 & SEEN_DATAREF) {
236 if (offsetof(struct sk_buff, len) <= 127)
237 /* mov off8(%rdi),%r9d */
238 EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
239 else {
240 /* mov off32(%rdi),%r9d */
241 EMIT3(0x44, 0x8b, 0x8f);
242 EMIT(offsetof(struct sk_buff, len), 4);
243 }
244 if (is_imm8(offsetof(struct sk_buff, data_len)))
245 /* sub off8(%rdi),%r9d */
246 EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
247 else {
248 EMIT3(0x44, 0x2b, 0x8f);
249 EMIT(offsetof(struct sk_buff, data_len), 4);
250 }
251
252 if (is_imm8(offsetof(struct sk_buff, data)))
253 /* mov off8(%rdi),%r8 */
254 EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
255 else {
256 /* mov off32(%rdi),%r8 */
257 EMIT3(0x4c, 0x8b, 0x87);
258 EMIT(offsetof(struct sk_buff, data), 4);
259 }
260 }
261 }
262
263 switch (filter[0].code) {
264 case BPF_S_RET_K:
265 case BPF_S_LD_W_LEN:
266 case BPF_S_ANC_PROTOCOL:
267 case BPF_S_ANC_IFINDEX:
268 case BPF_S_ANC_MARK:
269 case BPF_S_ANC_RXHASH:
270 case BPF_S_ANC_CPU:
271 case BPF_S_ANC_VLAN_TAG:
272 case BPF_S_ANC_VLAN_TAG_PRESENT:
273 case BPF_S_ANC_QUEUE:
274 case BPF_S_ANC_PKTTYPE:
275 case BPF_S_LD_W_ABS:
276 case BPF_S_LD_H_ABS:
277 case BPF_S_LD_B_ABS:
278 /* first instruction sets A register (or is RET 'constant') */
279 break;
280 default:
281 /* make sure we dont leak kernel information to user */
282 CLEAR_A(); /* A = 0 */
283 }
284
285 for (i = 0; i < flen; i++) {
286 unsigned int K = filter[i].k;
287
288 switch (filter[i].code) {
289 case BPF_S_ALU_ADD_X: /* A += X; */
290 seen |= SEEN_XREG;
291 EMIT2(0x01, 0xd8); /* add %ebx,%eax */
292 break;
293 case BPF_S_ALU_ADD_K: /* A += K; */
294 if (!K)
295 break;
296 if (is_imm8(K))
297 EMIT3(0x83, 0xc0, K); /* add imm8,%eax */
298 else
299 EMIT1_off32(0x05, K); /* add imm32,%eax */
300 break;
301 case BPF_S_ALU_SUB_X: /* A -= X; */
302 seen |= SEEN_XREG;
303 EMIT2(0x29, 0xd8); /* sub %ebx,%eax */
304 break;
305 case BPF_S_ALU_SUB_K: /* A -= K */
306 if (!K)
307 break;
308 if (is_imm8(K))
309 EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
310 else
311 EMIT1_off32(0x2d, K); /* sub imm32,%eax */
312 break;
313 case BPF_S_ALU_MUL_X: /* A *= X; */
314 seen |= SEEN_XREG;
315 EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */
316 break;
317 case BPF_S_ALU_MUL_K: /* A *= K */
318 if (is_imm8(K))
319 EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
320 else {
321 EMIT2(0x69, 0xc0); /* imul imm32,%eax */
322 EMIT(K, 4);
323 }
324 break;
325 case BPF_S_ALU_DIV_X: /* A /= X; */
326 seen |= SEEN_XREG;
327 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
328 if (pc_ret0 > 0) {
329 /* addrs[pc_ret0 - 1] is start address of target
330 * (addrs[i] - 4) is the address following this jmp
331 * ("xor %edx,%edx; div %ebx" being 4 bytes long)
332 */
333 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
334 (addrs[i] - 4));
335 } else {
336 EMIT_COND_JMP(X86_JNE, 2 + 5);
337 CLEAR_A();
338 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
339 }
340 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
341 break;
342 case BPF_S_ALU_MOD_X: /* A %= X; */
343 seen |= SEEN_XREG;
344 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
345 if (pc_ret0 > 0) {
346 /* addrs[pc_ret0 - 1] is start address of target
347 * (addrs[i] - 6) is the address following this jmp
348 * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long)
349 */
350 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
351 (addrs[i] - 6));
352 } else {
353 EMIT_COND_JMP(X86_JNE, 2 + 5);
354 CLEAR_A();
355 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 6)); /* jmp .+off32 */
356 }
357 EMIT2(0x31, 0xd2); /* xor %edx,%edx */
358 EMIT2(0xf7, 0xf3); /* div %ebx */
359 EMIT2(0x89, 0xd0); /* mov %edx,%eax */
360 break;
361 case BPF_S_ALU_MOD_K: /* A %= K; */
362 if (K == 1) {
363 CLEAR_A();
364 break;
365 }
366 EMIT2(0x31, 0xd2); /* xor %edx,%edx */
367 EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */
368 EMIT2(0xf7, 0xf1); /* div %ecx */
369 EMIT2(0x89, 0xd0); /* mov %edx,%eax */
370 break;
371 case BPF_S_ALU_DIV_K: /* A /= K */
372 if (K == 1)
373 break;
374 EMIT2(0x31, 0xd2); /* xor %edx,%edx */
375 EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */
376 EMIT2(0xf7, 0xf1); /* div %ecx */
377 break;
378 case BPF_S_ALU_AND_X:
379 seen |= SEEN_XREG;
380 EMIT2(0x21, 0xd8); /* and %ebx,%eax */
381 break;
382 case BPF_S_ALU_AND_K:
383 if (K >= 0xFFFFFF00) {
384 EMIT2(0x24, K & 0xFF); /* and imm8,%al */
385 } else if (K >= 0xFFFF0000) {
386 EMIT2(0x66, 0x25); /* and imm16,%ax */
387 EMIT(K, 2);
388 } else {
389 EMIT1_off32(0x25, K); /* and imm32,%eax */
390 }
391 break;
392 case BPF_S_ALU_OR_X:
393 seen |= SEEN_XREG;
394 EMIT2(0x09, 0xd8); /* or %ebx,%eax */
395 break;
396 case BPF_S_ALU_OR_K:
397 if (is_imm8(K))
398 EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
399 else
400 EMIT1_off32(0x0d, K); /* or imm32,%eax */
401 break;
402 case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
403 case BPF_S_ALU_XOR_X:
404 seen |= SEEN_XREG;
405 EMIT2(0x31, 0xd8); /* xor %ebx,%eax */
406 break;
407 case BPF_S_ALU_XOR_K: /* A ^= K; */
408 if (K == 0)
409 break;
410 if (is_imm8(K))
411 EMIT3(0x83, 0xf0, K); /* xor imm8,%eax */
412 else
413 EMIT1_off32(0x35, K); /* xor imm32,%eax */
414 break;
415 case BPF_S_ALU_LSH_X: /* A <<= X; */
416 seen |= SEEN_XREG;
417 EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */
418 break;
419 case BPF_S_ALU_LSH_K:
420 if (K == 0)
421 break;
422 else if (K == 1)
423 EMIT2(0xd1, 0xe0); /* shl %eax */
424 else
425 EMIT3(0xc1, 0xe0, K);
426 break;
427 case BPF_S_ALU_RSH_X: /* A >>= X; */
428 seen |= SEEN_XREG;
429 EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */
430 break;
431 case BPF_S_ALU_RSH_K: /* A >>= K; */
432 if (K == 0)
433 break;
434 else if (K == 1)
435 EMIT2(0xd1, 0xe8); /* shr %eax */
436 else
437 EMIT3(0xc1, 0xe8, K);
438 break;
439 case BPF_S_ALU_NEG:
440 EMIT2(0xf7, 0xd8); /* neg %eax */
441 break;
442 case BPF_S_RET_K:
443 if (!K) {
444 if (pc_ret0 == -1)
445 pc_ret0 = i;
446 CLEAR_A();
447 } else {
448 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
449 }
450 /* fallinto */
451 case BPF_S_RET_A:
452 if (seen_or_pass0) {
453 if (i != flen - 1) {
454 EMIT_JMP(cleanup_addr - addrs[i]);
455 break;
456 }
457 if (seen_or_pass0 & SEEN_XREG)
458 EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */
459 EMIT1(0xc9); /* leaveq */
460 }
461 EMIT1(0xc3); /* ret */
462 break;
463 case BPF_S_MISC_TAX: /* X = A */
464 seen |= SEEN_XREG;
465 EMIT2(0x89, 0xc3); /* mov %eax,%ebx */
466 break;
467 case BPF_S_MISC_TXA: /* A = X */
468 seen |= SEEN_XREG;
469 EMIT2(0x89, 0xd8); /* mov %ebx,%eax */
470 break;
471 case BPF_S_LD_IMM: /* A = K */
472 if (!K)
473 CLEAR_A();
474 else
475 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
476 break;
477 case BPF_S_LDX_IMM: /* X = K */
478 seen |= SEEN_XREG;
479 if (!K)
480 CLEAR_X();
481 else
482 EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
483 break;
484 case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
485 seen |= SEEN_MEM;
486 EMIT3(0x8b, 0x45, 0xf0 - K*4);
487 break;
488 case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
489 seen |= SEEN_XREG | SEEN_MEM;
490 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
491 break;
492 case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
493 seen |= SEEN_MEM;
494 EMIT3(0x89, 0x45, 0xf0 - K*4);
495 break;
496 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
497 seen |= SEEN_XREG | SEEN_MEM;
498 EMIT3(0x89, 0x5d, 0xf0 - K*4);
499 break;
500 case BPF_S_LD_W_LEN: /* A = skb->len; */
501 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
502 if (is_imm8(offsetof(struct sk_buff, len)))
503 /* mov off8(%rdi),%eax */
504 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
505 else {
506 EMIT2(0x8b, 0x87);
507 EMIT(offsetof(struct sk_buff, len), 4);
508 }
509 break;
510 case BPF_S_LDX_W_LEN: /* X = skb->len; */
511 seen |= SEEN_XREG;
512 if (is_imm8(offsetof(struct sk_buff, len)))
513 /* mov off8(%rdi),%ebx */
514 EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
515 else {
516 EMIT2(0x8b, 0x9f);
517 EMIT(offsetof(struct sk_buff, len), 4);
518 }
519 break;
520 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
521 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
522 if (is_imm8(offsetof(struct sk_buff, protocol))) {
523 /* movzwl off8(%rdi),%eax */
524 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
525 } else {
526 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
527 EMIT(offsetof(struct sk_buff, protocol), 4);
528 }
529 EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */
530 break;
531 case BPF_S_ANC_IFINDEX:
532 if (is_imm8(offsetof(struct sk_buff, dev))) {
533 /* movq off8(%rdi),%rax */
534 EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
535 } else {
536 EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
537 EMIT(offsetof(struct sk_buff, dev), 4);
538 }
539 EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */
540 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
541 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
542 EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */
543 EMIT(offsetof(struct net_device, ifindex), 4);
544 break;
545 case BPF_S_ANC_MARK:
546 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
547 if (is_imm8(offsetof(struct sk_buff, mark))) {
548 /* mov off8(%rdi),%eax */
549 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
550 } else {
551 EMIT2(0x8b, 0x87);
552 EMIT(offsetof(struct sk_buff, mark), 4);
553 }
554 break;
555 case BPF_S_ANC_RXHASH:
556 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
557 if (is_imm8(offsetof(struct sk_buff, hash))) {
558 /* mov off8(%rdi),%eax */
559 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, hash));
560 } else {
561 EMIT2(0x8b, 0x87);
562 EMIT(offsetof(struct sk_buff, hash), 4);
563 }
564 break;
565 case BPF_S_ANC_QUEUE:
566 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
567 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
568 /* movzwl off8(%rdi),%eax */
569 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
570 } else {
571 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
572 EMIT(offsetof(struct sk_buff, queue_mapping), 4);
573 }
574 break;
575 case BPF_S_ANC_CPU:
576#ifdef CONFIG_SMP
577 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
578 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
579#else
580 CLEAR_A();
581#endif
582 break;
583 case BPF_S_ANC_VLAN_TAG:
584 case BPF_S_ANC_VLAN_TAG_PRESENT:
585 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
586 if (is_imm8(offsetof(struct sk_buff, vlan_tci))) {
587 /* movzwl off8(%rdi),%eax */
588 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, vlan_tci));
589 } else {
590 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
591 EMIT(offsetof(struct sk_buff, vlan_tci), 4);
592 }
593 BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
594 if (filter[i].code == BPF_S_ANC_VLAN_TAG) {
595 EMIT3(0x80, 0xe4, 0xef); /* and $0xef,%ah */
596 } else {
597 EMIT3(0xc1, 0xe8, 0x0c); /* shr $0xc,%eax */
598 EMIT3(0x83, 0xe0, 0x01); /* and $0x1,%eax */
599 }
600 break;
601 case BPF_S_ANC_PKTTYPE:
602 {
603 int off = pkt_type_offset();
604
605 if (off < 0)
606 goto out;
607 if (is_imm8(off)) {
608 /* movzbl off8(%rdi),%eax */
609 EMIT4(0x0f, 0xb6, 0x47, off);
610 } else {
611 /* movbl off32(%rdi),%eax */
612 EMIT3(0x0f, 0xb6, 0x87);
613 EMIT(off, 4);
614 }
615 EMIT3(0x83, 0xe0, PKT_TYPE_MAX); /* and $0x7,%eax */
616 break;
617 }
618 case BPF_S_LD_W_ABS:
619 func = CHOOSE_LOAD_FUNC(K, sk_load_word);
620common_load: seen |= SEEN_DATAREF;
621 t_offset = func - (image + addrs[i]);
622 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
623 EMIT1_off32(0xe8, t_offset); /* call */
624 break;
625 case BPF_S_LD_H_ABS:
626 func = CHOOSE_LOAD_FUNC(K, sk_load_half);
627 goto common_load;
628 case BPF_S_LD_B_ABS:
629 func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
630 goto common_load;
631 case BPF_S_LDX_B_MSH:
632 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
633 seen |= SEEN_DATAREF | SEEN_XREG;
634 t_offset = func - (image + addrs[i]);
635 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
636 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
637 break;
638 case BPF_S_LD_W_IND:
639 func = sk_load_word;
640common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG;
641 t_offset = func - (image + addrs[i]);
642 if (K) {
643 if (is_imm8(K)) {
644 EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */
645 } else {
646 EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */
647 EMIT(K, 4);
648 }
649 } else {
650 EMIT2(0x89,0xde); /* mov %ebx,%esi */
651 }
652 EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */
653 break;
654 case BPF_S_LD_H_IND:
655 func = sk_load_half;
656 goto common_load_ind;
657 case BPF_S_LD_B_IND:
658 func = sk_load_byte;
659 goto common_load_ind;
660 case BPF_S_JMP_JA:
661 t_offset = addrs[i + K] - addrs[i];
662 EMIT_JMP(t_offset);
663 break;
664 COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
665 COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
666 COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
667 COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
668 COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
669 COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
670 COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
671 COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
672
673cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
674 t_offset = addrs[i + filter[i].jt] - addrs[i];
675
676 /* same targets, can avoid doing the test :) */
677 if (filter[i].jt == filter[i].jf) {
678 EMIT_JMP(t_offset);
679 break;
680 }
681
682 switch (filter[i].code) {
683 case BPF_S_JMP_JGT_X:
684 case BPF_S_JMP_JGE_X:
685 case BPF_S_JMP_JEQ_X:
686 seen |= SEEN_XREG;
687 EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
688 break;
689 case BPF_S_JMP_JSET_X:
690 seen |= SEEN_XREG;
691 EMIT2(0x85, 0xd8); /* test %ebx,%eax */
692 break;
693 case BPF_S_JMP_JEQ_K:
694 if (K == 0) {
695 EMIT2(0x85, 0xc0); /* test %eax,%eax */
696 break;
697 }
698 case BPF_S_JMP_JGT_K:
699 case BPF_S_JMP_JGE_K:
700 if (K <= 127)
701 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
702 else
703 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
704 break;
705 case BPF_S_JMP_JSET_K:
706 if (K <= 0xFF)
707 EMIT2(0xa8, K); /* test imm8,%al */
708 else if (!(K & 0xFFFF00FF))
709 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
710 else if (K <= 0xFFFF) {
711 EMIT2(0x66, 0xa9); /* test imm16,%ax */
712 EMIT(K, 2);
713 } else {
714 EMIT1_off32(0xa9, K); /* test imm32,%eax */
715 }
716 break;
717 }
718 if (filter[i].jt != 0) {
719 if (filter[i].jf && f_offset)
720 t_offset += is_near(f_offset) ? 2 : 5;
721 EMIT_COND_JMP(t_op, t_offset);
722 if (filter[i].jf)
723 EMIT_JMP(f_offset);
724 break;
725 }
726 EMIT_COND_JMP(f_op, f_offset);
727 break;
728 default:
729 /* hmm, too complex filter, give up with jit compiler */
730 goto out;
731 }
732 ilen = prog - temp;
733 if (image) {
734 if (unlikely(proglen + ilen > oldproglen)) {
735 pr_err("bpb_jit_compile fatal error\n");
736 kfree(addrs);
737 module_free(NULL, header);
738 return;
739 }
740 memcpy(image + proglen, temp, ilen);
741 }
742 proglen += ilen;
743 addrs[i] = proglen;
744 prog = temp;
745 }
746 /* last bpf instruction is always a RET :
747 * use it to give the cleanup instruction(s) addr
748 */
749 cleanup_addr = proglen - 1; /* ret */
750 if (seen_or_pass0)
751 cleanup_addr -= 1; /* leaveq */
752 if (seen_or_pass0 & SEEN_XREG)
753 cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
754
755 if (image) {
756 if (proglen != oldproglen)
757 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
758 break;
759 }
760 if (proglen == oldproglen) {
761 header = bpf_alloc_binary(proglen, &image);
762 if (!header)
763 goto out;
764 }
765 oldproglen = proglen;
766 }
767
768 if (bpf_jit_enable > 1)
769 bpf_jit_dump(flen, proglen, pass, image);
770
771 if (image) {
772 bpf_flush_icache(header, image + proglen);
773 set_memory_ro((unsigned long)header, header->pages);
774 fp->bpf_func = (void *)image;
775 fp->jited = 1;
776 }
777out:
778 kfree(addrs);
779 return;
780}
781
782static void bpf_jit_free_deferred(struct work_struct *work)
783{
784 struct sk_filter *fp = container_of(work, struct sk_filter, work);
785 unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
786 struct bpf_binary_header *header = (void *)addr;
787
788 set_memory_rw(addr, header->pages);
789 module_free(NULL, header);
790 kfree(fp);
791}
792
793void bpf_jit_free(struct sk_filter *fp)
794{
795 if (fp->jited) {
796 INIT_WORK(&fp->work, bpf_jit_free_deferred);
797 schedule_work(&fp->work);
798 } else {
799 kfree(fp);
800 }
801}
1/* bpf_jit_comp.c : BPF JIT compiler
2 *
3 * Copyright (C) 2011 Eric Dumazet (eric.dumazet@gmail.com)
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; version 2
8 * of the License.
9 */
10#include <linux/moduleloader.h>
11#include <asm/cacheflush.h>
12#include <linux/netdevice.h>
13#include <linux/filter.h>
14
15/*
16 * Conventions :
17 * EAX : BPF A accumulator
18 * EBX : BPF X accumulator
19 * RDI : pointer to skb (first argument given to JIT function)
20 * RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
21 * ECX,EDX,ESI : scratch registers
22 * r9d : skb->len - skb->data_len (headlen)
23 * r8 : skb->data
24 * -8(RBP) : saved RBX value
25 * -16(RBP)..-80(RBP) : BPF_MEMWORDS values
26 */
27int bpf_jit_enable __read_mostly;
28
29/*
30 * assembly code in arch/x86/net/bpf_jit.S
31 */
32extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
33extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
34
35static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
36{
37 if (len == 1)
38 *ptr = bytes;
39 else if (len == 2)
40 *(u16 *)ptr = bytes;
41 else {
42 *(u32 *)ptr = bytes;
43 barrier();
44 }
45 return ptr + len;
46}
47
48#define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0)
49
50#define EMIT1(b1) EMIT(b1, 1)
51#define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
52#define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
53#define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
54#define EMIT1_off32(b1, off) do { EMIT1(b1); EMIT(off, 4);} while (0)
55
56#define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
57#define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
58
59static inline bool is_imm8(int value)
60{
61 return value <= 127 && value >= -128;
62}
63
64static inline bool is_near(int offset)
65{
66 return offset <= 127 && offset >= -128;
67}
68
69#define EMIT_JMP(offset) \
70do { \
71 if (offset) { \
72 if (is_near(offset)) \
73 EMIT2(0xeb, offset); /* jmp .+off8 */ \
74 else \
75 EMIT1_off32(0xe9, offset); /* jmp .+off32 */ \
76 } \
77} while (0)
78
79/* list of x86 cond jumps opcodes (. + s8)
80 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
81 */
82#define X86_JB 0x72
83#define X86_JAE 0x73
84#define X86_JE 0x74
85#define X86_JNE 0x75
86#define X86_JBE 0x76
87#define X86_JA 0x77
88
89#define EMIT_COND_JMP(op, offset) \
90do { \
91 if (is_near(offset)) \
92 EMIT2(op, offset); /* jxx .+off8 */ \
93 else { \
94 EMIT2(0x0f, op + 0x10); \
95 EMIT(offset, 4); /* jxx .+off32 */ \
96 } \
97} while (0)
98
99#define COND_SEL(CODE, TOP, FOP) \
100 case CODE: \
101 t_op = TOP; \
102 f_op = FOP; \
103 goto cond_branch
104
105
106#define SEEN_DATAREF 1 /* might call external helpers */
107#define SEEN_XREG 2 /* ebx is used */
108#define SEEN_MEM 4 /* use mem[] for temporary storage */
109
110static inline void bpf_flush_icache(void *start, void *end)
111{
112 mm_segment_t old_fs = get_fs();
113
114 set_fs(KERNEL_DS);
115 smp_wmb();
116 flush_icache_range((unsigned long)start, (unsigned long)end);
117 set_fs(old_fs);
118}
119
120
121void bpf_jit_compile(struct sk_filter *fp)
122{
123 u8 temp[64];
124 u8 *prog;
125 unsigned int proglen, oldproglen = 0;
126 int ilen, i;
127 int t_offset, f_offset;
128 u8 t_op, f_op, seen = 0, pass;
129 u8 *image = NULL;
130 u8 *func;
131 int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
132 unsigned int cleanup_addr; /* epilogue code offset */
133 unsigned int *addrs;
134 const struct sock_filter *filter = fp->insns;
135 int flen = fp->len;
136
137 if (!bpf_jit_enable)
138 return;
139
140 addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
141 if (addrs == NULL)
142 return;
143
144 /* Before first pass, make a rough estimation of addrs[]
145 * each bpf instruction is translated to less than 64 bytes
146 */
147 for (proglen = 0, i = 0; i < flen; i++) {
148 proglen += 64;
149 addrs[i] = proglen;
150 }
151 cleanup_addr = proglen; /* epilogue address */
152
153 for (pass = 0; pass < 10; pass++) {
154 /* no prologue/epilogue for trivial filters (RET something) */
155 proglen = 0;
156 prog = temp;
157
158 if (seen) {
159 EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
160 EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */
161 /* note : must save %rbx in case bpf_error is hit */
162 if (seen & (SEEN_XREG | SEEN_DATAREF))
163 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
164 if (seen & SEEN_XREG)
165 CLEAR_X(); /* make sure we dont leek kernel memory */
166
167 /*
168 * If this filter needs to access skb data,
169 * loads r9 and r8 with :
170 * r9 = skb->len - skb->data_len
171 * r8 = skb->data
172 */
173 if (seen & SEEN_DATAREF) {
174 if (offsetof(struct sk_buff, len) <= 127)
175 /* mov off8(%rdi),%r9d */
176 EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
177 else {
178 /* mov off32(%rdi),%r9d */
179 EMIT3(0x44, 0x8b, 0x8f);
180 EMIT(offsetof(struct sk_buff, len), 4);
181 }
182 if (is_imm8(offsetof(struct sk_buff, data_len)))
183 /* sub off8(%rdi),%r9d */
184 EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
185 else {
186 EMIT3(0x44, 0x2b, 0x8f);
187 EMIT(offsetof(struct sk_buff, data_len), 4);
188 }
189
190 if (is_imm8(offsetof(struct sk_buff, data)))
191 /* mov off8(%rdi),%r8 */
192 EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
193 else {
194 /* mov off32(%rdi),%r8 */
195 EMIT3(0x4c, 0x8b, 0x87);
196 EMIT(offsetof(struct sk_buff, data), 4);
197 }
198 }
199 }
200
201 switch (filter[0].code) {
202 case BPF_S_RET_K:
203 case BPF_S_LD_W_LEN:
204 case BPF_S_ANC_PROTOCOL:
205 case BPF_S_ANC_IFINDEX:
206 case BPF_S_ANC_MARK:
207 case BPF_S_ANC_RXHASH:
208 case BPF_S_ANC_CPU:
209 case BPF_S_ANC_QUEUE:
210 case BPF_S_LD_W_ABS:
211 case BPF_S_LD_H_ABS:
212 case BPF_S_LD_B_ABS:
213 /* first instruction sets A register (or is RET 'constant') */
214 break;
215 default:
216 /* make sure we dont leak kernel information to user */
217 CLEAR_A(); /* A = 0 */
218 }
219
220 for (i = 0; i < flen; i++) {
221 unsigned int K = filter[i].k;
222
223 switch (filter[i].code) {
224 case BPF_S_ALU_ADD_X: /* A += X; */
225 seen |= SEEN_XREG;
226 EMIT2(0x01, 0xd8); /* add %ebx,%eax */
227 break;
228 case BPF_S_ALU_ADD_K: /* A += K; */
229 if (!K)
230 break;
231 if (is_imm8(K))
232 EMIT3(0x83, 0xc0, K); /* add imm8,%eax */
233 else
234 EMIT1_off32(0x05, K); /* add imm32,%eax */
235 break;
236 case BPF_S_ALU_SUB_X: /* A -= X; */
237 seen |= SEEN_XREG;
238 EMIT2(0x29, 0xd8); /* sub %ebx,%eax */
239 break;
240 case BPF_S_ALU_SUB_K: /* A -= K */
241 if (!K)
242 break;
243 if (is_imm8(K))
244 EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
245 else
246 EMIT1_off32(0x2d, K); /* sub imm32,%eax */
247 break;
248 case BPF_S_ALU_MUL_X: /* A *= X; */
249 seen |= SEEN_XREG;
250 EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */
251 break;
252 case BPF_S_ALU_MUL_K: /* A *= K */
253 if (is_imm8(K))
254 EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
255 else {
256 EMIT2(0x69, 0xc0); /* imul imm32,%eax */
257 EMIT(K, 4);
258 }
259 break;
260 case BPF_S_ALU_DIV_X: /* A /= X; */
261 seen |= SEEN_XREG;
262 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
263 if (pc_ret0 != -1)
264 EMIT_COND_JMP(X86_JE, addrs[pc_ret0] - (addrs[i] - 4));
265 else {
266 EMIT_COND_JMP(X86_JNE, 2 + 5);
267 CLEAR_A();
268 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
269 }
270 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
271 break;
272 case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
273 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
274 EMIT(K, 4);
275 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
276 break;
277 case BPF_S_ALU_AND_X:
278 seen |= SEEN_XREG;
279 EMIT2(0x21, 0xd8); /* and %ebx,%eax */
280 break;
281 case BPF_S_ALU_AND_K:
282 if (K >= 0xFFFFFF00) {
283 EMIT2(0x24, K & 0xFF); /* and imm8,%al */
284 } else if (K >= 0xFFFF0000) {
285 EMIT2(0x66, 0x25); /* and imm16,%ax */
286 EMIT2(K, 2);
287 } else {
288 EMIT1_off32(0x25, K); /* and imm32,%eax */
289 }
290 break;
291 case BPF_S_ALU_OR_X:
292 seen |= SEEN_XREG;
293 EMIT2(0x09, 0xd8); /* or %ebx,%eax */
294 break;
295 case BPF_S_ALU_OR_K:
296 if (is_imm8(K))
297 EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
298 else
299 EMIT1_off32(0x0d, K); /* or imm32,%eax */
300 break;
301 case BPF_S_ALU_LSH_X: /* A <<= X; */
302 seen |= SEEN_XREG;
303 EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */
304 break;
305 case BPF_S_ALU_LSH_K:
306 if (K == 0)
307 break;
308 else if (K == 1)
309 EMIT2(0xd1, 0xe0); /* shl %eax */
310 else
311 EMIT3(0xc1, 0xe0, K);
312 break;
313 case BPF_S_ALU_RSH_X: /* A >>= X; */
314 seen |= SEEN_XREG;
315 EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */
316 break;
317 case BPF_S_ALU_RSH_K: /* A >>= K; */
318 if (K == 0)
319 break;
320 else if (K == 1)
321 EMIT2(0xd1, 0xe8); /* shr %eax */
322 else
323 EMIT3(0xc1, 0xe8, K);
324 break;
325 case BPF_S_ALU_NEG:
326 EMIT2(0xf7, 0xd8); /* neg %eax */
327 break;
328 case BPF_S_RET_K:
329 if (!K) {
330 if (pc_ret0 == -1)
331 pc_ret0 = i;
332 CLEAR_A();
333 } else {
334 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
335 }
336 /* fallinto */
337 case BPF_S_RET_A:
338 if (seen) {
339 if (i != flen - 1) {
340 EMIT_JMP(cleanup_addr - addrs[i]);
341 break;
342 }
343 if (seen & SEEN_XREG)
344 EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */
345 EMIT1(0xc9); /* leaveq */
346 }
347 EMIT1(0xc3); /* ret */
348 break;
349 case BPF_S_MISC_TAX: /* X = A */
350 seen |= SEEN_XREG;
351 EMIT2(0x89, 0xc3); /* mov %eax,%ebx */
352 break;
353 case BPF_S_MISC_TXA: /* A = X */
354 seen |= SEEN_XREG;
355 EMIT2(0x89, 0xd8); /* mov %ebx,%eax */
356 break;
357 case BPF_S_LD_IMM: /* A = K */
358 if (!K)
359 CLEAR_A();
360 else
361 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
362 break;
363 case BPF_S_LDX_IMM: /* X = K */
364 seen |= SEEN_XREG;
365 if (!K)
366 CLEAR_X();
367 else
368 EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
369 break;
370 case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
371 seen |= SEEN_MEM;
372 EMIT3(0x8b, 0x45, 0xf0 - K*4);
373 break;
374 case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
375 seen |= SEEN_XREG | SEEN_MEM;
376 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
377 break;
378 case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
379 seen |= SEEN_MEM;
380 EMIT3(0x89, 0x45, 0xf0 - K*4);
381 break;
382 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
383 seen |= SEEN_XREG | SEEN_MEM;
384 EMIT3(0x89, 0x5d, 0xf0 - K*4);
385 break;
386 case BPF_S_LD_W_LEN: /* A = skb->len; */
387 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
388 if (is_imm8(offsetof(struct sk_buff, len)))
389 /* mov off8(%rdi),%eax */
390 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
391 else {
392 EMIT2(0x8b, 0x87);
393 EMIT(offsetof(struct sk_buff, len), 4);
394 }
395 break;
396 case BPF_S_LDX_W_LEN: /* X = skb->len; */
397 seen |= SEEN_XREG;
398 if (is_imm8(offsetof(struct sk_buff, len)))
399 /* mov off8(%rdi),%ebx */
400 EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
401 else {
402 EMIT2(0x8b, 0x9f);
403 EMIT(offsetof(struct sk_buff, len), 4);
404 }
405 break;
406 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
407 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
408 if (is_imm8(offsetof(struct sk_buff, protocol))) {
409 /* movzwl off8(%rdi),%eax */
410 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
411 } else {
412 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
413 EMIT(offsetof(struct sk_buff, protocol), 4);
414 }
415 EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */
416 break;
417 case BPF_S_ANC_IFINDEX:
418 if (is_imm8(offsetof(struct sk_buff, dev))) {
419 /* movq off8(%rdi),%rax */
420 EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
421 } else {
422 EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
423 EMIT(offsetof(struct sk_buff, dev), 4);
424 }
425 EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */
426 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
427 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
428 EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */
429 EMIT(offsetof(struct net_device, ifindex), 4);
430 break;
431 case BPF_S_ANC_MARK:
432 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
433 if (is_imm8(offsetof(struct sk_buff, mark))) {
434 /* mov off8(%rdi),%eax */
435 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
436 } else {
437 EMIT2(0x8b, 0x87);
438 EMIT(offsetof(struct sk_buff, mark), 4);
439 }
440 break;
441 case BPF_S_ANC_RXHASH:
442 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
443 if (is_imm8(offsetof(struct sk_buff, rxhash))) {
444 /* mov off8(%rdi),%eax */
445 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
446 } else {
447 EMIT2(0x8b, 0x87);
448 EMIT(offsetof(struct sk_buff, rxhash), 4);
449 }
450 break;
451 case BPF_S_ANC_QUEUE:
452 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
453 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
454 /* movzwl off8(%rdi),%eax */
455 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
456 } else {
457 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
458 EMIT(offsetof(struct sk_buff, queue_mapping), 4);
459 }
460 break;
461 case BPF_S_ANC_CPU:
462#ifdef CONFIG_SMP
463 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
464 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
465#else
466 CLEAR_A();
467#endif
468 break;
469 case BPF_S_LD_W_ABS:
470 func = sk_load_word;
471common_load: seen |= SEEN_DATAREF;
472 if ((int)K < 0)
473 goto out;
474 t_offset = func - (image + addrs[i]);
475 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
476 EMIT1_off32(0xe8, t_offset); /* call */
477 break;
478 case BPF_S_LD_H_ABS:
479 func = sk_load_half;
480 goto common_load;
481 case BPF_S_LD_B_ABS:
482 func = sk_load_byte;
483 goto common_load;
484 case BPF_S_LDX_B_MSH:
485 if ((int)K < 0) {
486 if (pc_ret0 != -1) {
487 EMIT_JMP(addrs[pc_ret0] - addrs[i]);
488 break;
489 }
490 CLEAR_A();
491 EMIT_JMP(cleanup_addr - addrs[i]);
492 break;
493 }
494 seen |= SEEN_DATAREF | SEEN_XREG;
495 t_offset = sk_load_byte_msh - (image + addrs[i]);
496 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
497 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
498 break;
499 case BPF_S_LD_W_IND:
500 func = sk_load_word_ind;
501common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG;
502 t_offset = func - (image + addrs[i]);
503 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
504 EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */
505 break;
506 case BPF_S_LD_H_IND:
507 func = sk_load_half_ind;
508 goto common_load_ind;
509 case BPF_S_LD_B_IND:
510 func = sk_load_byte_ind;
511 goto common_load_ind;
512 case BPF_S_JMP_JA:
513 t_offset = addrs[i + K] - addrs[i];
514 EMIT_JMP(t_offset);
515 break;
516 COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
517 COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
518 COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
519 COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
520 COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
521 COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
522 COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
523 COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
524
525cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
526 t_offset = addrs[i + filter[i].jt] - addrs[i];
527
528 /* same targets, can avoid doing the test :) */
529 if (filter[i].jt == filter[i].jf) {
530 EMIT_JMP(t_offset);
531 break;
532 }
533
534 switch (filter[i].code) {
535 case BPF_S_JMP_JGT_X:
536 case BPF_S_JMP_JGE_X:
537 case BPF_S_JMP_JEQ_X:
538 seen |= SEEN_XREG;
539 EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
540 break;
541 case BPF_S_JMP_JSET_X:
542 seen |= SEEN_XREG;
543 EMIT2(0x85, 0xd8); /* test %ebx,%eax */
544 break;
545 case BPF_S_JMP_JEQ_K:
546 if (K == 0) {
547 EMIT2(0x85, 0xc0); /* test %eax,%eax */
548 break;
549 }
550 case BPF_S_JMP_JGT_K:
551 case BPF_S_JMP_JGE_K:
552 if (K <= 127)
553 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
554 else
555 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
556 break;
557 case BPF_S_JMP_JSET_K:
558 if (K <= 0xFF)
559 EMIT2(0xa8, K); /* test imm8,%al */
560 else if (!(K & 0xFFFF00FF))
561 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
562 else if (K <= 0xFFFF) {
563 EMIT2(0x66, 0xa9); /* test imm16,%ax */
564 EMIT(K, 2);
565 } else {
566 EMIT1_off32(0xa9, K); /* test imm32,%eax */
567 }
568 break;
569 }
570 if (filter[i].jt != 0) {
571 if (filter[i].jf)
572 t_offset += is_near(f_offset) ? 2 : 6;
573 EMIT_COND_JMP(t_op, t_offset);
574 if (filter[i].jf)
575 EMIT_JMP(f_offset);
576 break;
577 }
578 EMIT_COND_JMP(f_op, f_offset);
579 break;
580 default:
581 /* hmm, too complex filter, give up with jit compiler */
582 goto out;
583 }
584 ilen = prog - temp;
585 if (image) {
586 if (unlikely(proglen + ilen > oldproglen)) {
587 pr_err("bpb_jit_compile fatal error\n");
588 kfree(addrs);
589 module_free(NULL, image);
590 return;
591 }
592 memcpy(image + proglen, temp, ilen);
593 }
594 proglen += ilen;
595 addrs[i] = proglen;
596 prog = temp;
597 }
598 /* last bpf instruction is always a RET :
599 * use it to give the cleanup instruction(s) addr
600 */
601 cleanup_addr = proglen - 1; /* ret */
602 if (seen)
603 cleanup_addr -= 1; /* leaveq */
604 if (seen & SEEN_XREG)
605 cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
606
607 if (image) {
608 WARN_ON(proglen != oldproglen);
609 break;
610 }
611 if (proglen == oldproglen) {
612 image = module_alloc(max_t(unsigned int,
613 proglen,
614 sizeof(struct work_struct)));
615 if (!image)
616 goto out;
617 }
618 oldproglen = proglen;
619 }
620 if (bpf_jit_enable > 1)
621 pr_err("flen=%d proglen=%u pass=%d image=%p\n",
622 flen, proglen, pass, image);
623
624 if (image) {
625 if (bpf_jit_enable > 1)
626 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
627 16, 1, image, proglen, false);
628
629 bpf_flush_icache(image, image + proglen);
630
631 fp->bpf_func = (void *)image;
632 }
633out:
634 kfree(addrs);
635 return;
636}
637
638static void jit_free_defer(struct work_struct *arg)
639{
640 module_free(NULL, arg);
641}
642
643/* run from softirq, we must use a work_struct to call
644 * module_free() from process context
645 */
646void bpf_jit_free(struct sk_filter *fp)
647{
648 if (fp->bpf_func != sk_run_filter) {
649 struct work_struct *work = (struct work_struct *)fp->bpf_func;
650
651 INIT_WORK(work, jit_free_defer);
652 schedule_work(work);
653 }
654}