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Linux 3.8-rc7
[cris-mirror.git] / arch / x86 / net / bpf_jit_comp.c
blobd11a47099d330d1dcdc21261df571212551f3f03
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 #include <linux/if_vlan.h>
15
16 /*
17 * Conventions :
18 * EAX : BPF A accumulator
19 * EBX : BPF X accumulator
20 * RDI : pointer to skb (first argument given to JIT function)
21 * RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
22 * ECX,EDX,ESI : scratch registers
23 * r9d : skb->len - skb->data_len (headlen)
24 * r8 : skb->data
25 * -8(RBP) : saved RBX value
26 * -16(RBP)..-80(RBP) : BPF_MEMWORDS values
27 */
28 int bpf_jit_enable __read_mostly;
29
30 /*
31 * assembly code in arch/x86/net/bpf_jit.S
32 */
33 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
34 extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[];
35 extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[];
36 extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
37 extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[];
38
39 static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
40 {
41 if (len == 1)
42 *ptr = bytes;
43 else if (len == 2)
44 *(u16 *)ptr = bytes;
45 else {
46 *(u32 *)ptr = bytes;
47 barrier();
48 }
49 return ptr + len;
50 }
51
52 #define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0)
53
54 #define EMIT1(b1) EMIT(b1, 1)
55 #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
56 #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
57 #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
58 #define EMIT1_off32(b1, off) do { EMIT1(b1); EMIT(off, 4);} while (0)
59
60 #define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
61 #define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
62
63 static inline bool is_imm8(int value)
64 {
65 return value <= 127 && value >= -128;
66 }
67
68 static inline bool is_near(int offset)
69 {
70 return offset <= 127 && offset >= -128;
71 }
72
73 #define EMIT_JMP(offset) \
74 do { \
75 if (offset) { \
76 if (is_near(offset)) \
77 EMIT2(0xeb, offset); /* jmp .+off8 */ \
78 else \
79 EMIT1_off32(0xe9, offset); /* jmp .+off32 */ \
80 } \
81 } while (0)
82
83 /* list of x86 cond jumps opcodes (. + s8)
84 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
85 */
86 #define X86_JB 0x72
87 #define X86_JAE 0x73
88 #define X86_JE 0x74
89 #define X86_JNE 0x75
90 #define X86_JBE 0x76
91 #define X86_JA 0x77
92
93 #define EMIT_COND_JMP(op, offset) \
94 do { \
95 if (is_near(offset)) \
96 EMIT2(op, offset); /* jxx .+off8 */ \
97 else { \
98 EMIT2(0x0f, op + 0x10); \
99 EMIT(offset, 4); /* jxx .+off32 */ \
100 } \
101 } while (0)
102
103 #define COND_SEL(CODE, TOP, FOP) \
104 case CODE: \
105 t_op = TOP; \
106 f_op = FOP; \
107 goto cond_branch
108
109
110 #define SEEN_DATAREF 1 /* might call external helpers */
111 #define SEEN_XREG 2 /* ebx is used */
112 #define SEEN_MEM 4 /* use mem[] for temporary storage */
113
114 static inline void bpf_flush_icache(void *start, void *end)
115 {
116 mm_segment_t old_fs = get_fs();
117
118 set_fs(KERNEL_DS);
119 smp_wmb();
120 flush_icache_range((unsigned long)start, (unsigned long)end);
121 set_fs(old_fs);
122 }
123
124 #define CHOOSE_LOAD_FUNC(K, func) \
125 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
126
127 void bpf_jit_compile(struct sk_filter *fp)
128 {
129 u8 temp[64];
130 u8 *prog;
131 unsigned int proglen, oldproglen = 0;
132 int ilen, i;
133 int t_offset, f_offset;
134 u8 t_op, f_op, seen = 0, pass;
135 u8 *image = NULL;
136 u8 *func;
137 int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
138 unsigned int cleanup_addr; /* epilogue code offset */
139 unsigned int *addrs;
140 const struct sock_filter *filter = fp->insns;
141 int flen = fp->len;
142
143 if (!bpf_jit_enable)
144 return;
145
146 addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
147 if (addrs == NULL)
148 return;
149
150 /* Before first pass, make a rough estimation of addrs[]
151 * each bpf instruction is translated to less than 64 bytes
152 */
153 for (proglen = 0, i = 0; i < flen; i++) {
154 proglen += 64;
155 addrs[i] = proglen;
156 }
157 cleanup_addr = proglen; /* epilogue address */
158
159 for (pass = 0; pass < 10; pass++) {
160 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
161 /* no prologue/epilogue for trivial filters (RET something) */
162 proglen = 0;
163 prog = temp;
164
165 if (seen_or_pass0) {
166 EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
167 EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */
168 /* note : must save %rbx in case bpf_error is hit */
169 if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
170 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
171 if (seen_or_pass0 & SEEN_XREG)
172 CLEAR_X(); /* make sure we dont leek kernel memory */
173
174 /*
175 * If this filter needs to access skb data,
176 * loads r9 and r8 with :
177 * r9 = skb->len - skb->data_len
178 * r8 = skb->data
179 */
180 if (seen_or_pass0 & SEEN_DATAREF) {
181 if (offsetof(struct sk_buff, len) <= 127)
182 /* mov off8(%rdi),%r9d */
183 EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
184 else {
185 /* mov off32(%rdi),%r9d */
186 EMIT3(0x44, 0x8b, 0x8f);
187 EMIT(offsetof(struct sk_buff, len), 4);
188 }
189 if (is_imm8(offsetof(struct sk_buff, data_len)))
190 /* sub off8(%rdi),%r9d */
191 EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
192 else {
193 EMIT3(0x44, 0x2b, 0x8f);
194 EMIT(offsetof(struct sk_buff, data_len), 4);
195 }
196
197 if (is_imm8(offsetof(struct sk_buff, data)))
198 /* mov off8(%rdi),%r8 */
199 EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
200 else {
201 /* mov off32(%rdi),%r8 */
202 EMIT3(0x4c, 0x8b, 0x87);
203 EMIT(offsetof(struct sk_buff, data), 4);
204 }
205 }
206 }
207
208 switch (filter[0].code) {
209 case BPF_S_RET_K:
210 case BPF_S_LD_W_LEN:
211 case BPF_S_ANC_PROTOCOL:
212 case BPF_S_ANC_IFINDEX:
213 case BPF_S_ANC_MARK:
214 case BPF_S_ANC_RXHASH:
215 case BPF_S_ANC_CPU:
216 case BPF_S_ANC_VLAN_TAG:
217 case BPF_S_ANC_VLAN_TAG_PRESENT:
218 case BPF_S_ANC_QUEUE:
219 case BPF_S_LD_W_ABS:
220 case BPF_S_LD_H_ABS:
221 case BPF_S_LD_B_ABS:
222 /* first instruction sets A register (or is RET 'constant') */
223 break;
224 default:
225 /* make sure we dont leak kernel information to user */
226 CLEAR_A(); /* A = 0 */
227 }
228
229 for (i = 0; i < flen; i++) {
230 unsigned int K = filter[i].k;
231
232 switch (filter[i].code) {
233 case BPF_S_ALU_ADD_X: /* A += X; */
234 seen |= SEEN_XREG;
235 EMIT2(0x01, 0xd8); /* add %ebx,%eax */
236 break;
237 case BPF_S_ALU_ADD_K: /* A += K; */
238 if (!K)
239 break;
240 if (is_imm8(K))
241 EMIT3(0x83, 0xc0, K); /* add imm8,%eax */
242 else
243 EMIT1_off32(0x05, K); /* add imm32,%eax */
244 break;
245 case BPF_S_ALU_SUB_X: /* A -= X; */
246 seen |= SEEN_XREG;
247 EMIT2(0x29, 0xd8); /* sub %ebx,%eax */
248 break;
249 case BPF_S_ALU_SUB_K: /* A -= K */
250 if (!K)
251 break;
252 if (is_imm8(K))
253 EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
254 else
255 EMIT1_off32(0x2d, K); /* sub imm32,%eax */
256 break;
257 case BPF_S_ALU_MUL_X: /* A *= X; */
258 seen |= SEEN_XREG;
259 EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */
260 break;
261 case BPF_S_ALU_MUL_K: /* A *= K */
262 if (is_imm8(K))
263 EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
264 else {
265 EMIT2(0x69, 0xc0); /* imul imm32,%eax */
266 EMIT(K, 4);
267 }
268 break;
269 case BPF_S_ALU_DIV_X: /* A /= X; */
270 seen |= SEEN_XREG;
271 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
272 if (pc_ret0 > 0) {
273 /* addrs[pc_ret0 - 1] is start address of target
274 * (addrs[i] - 4) is the address following this jmp
275 * ("xor %edx,%edx; div %ebx" being 4 bytes long)
276 */
277 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
278 (addrs[i] - 4));
279 } else {
280 EMIT_COND_JMP(X86_JNE, 2 + 5);
281 CLEAR_A();
282 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
283 }
284 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
285 break;
286 case BPF_S_ALU_MOD_X: /* A %= X; */
287 seen |= SEEN_XREG;
288 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
289 if (pc_ret0 > 0) {
290 /* addrs[pc_ret0 - 1] is start address of target
291 * (addrs[i] - 6) is the address following this jmp
292 * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long)
293 */
294 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
295 (addrs[i] - 6));
296 } else {
297 EMIT_COND_JMP(X86_JNE, 2 + 5);
298 CLEAR_A();
299 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 6)); /* jmp .+off32 */
300 }
301 EMIT2(0x31, 0xd2); /* xor %edx,%edx */
302 EMIT2(0xf7, 0xf3); /* div %ebx */
303 EMIT2(0x89, 0xd0); /* mov %edx,%eax */
304 break;
305 case BPF_S_ALU_MOD_K: /* A %= K; */
306 EMIT2(0x31, 0xd2); /* xor %edx,%edx */
307 EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */
308 EMIT2(0xf7, 0xf1); /* div %ecx */
309 EMIT2(0x89, 0xd0); /* mov %edx,%eax */
310 break;
311 case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
312 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
313 EMIT(K, 4);
314 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
315 break;
316 case BPF_S_ALU_AND_X:
317 seen |= SEEN_XREG;
318 EMIT2(0x21, 0xd8); /* and %ebx,%eax */
319 break;
320 case BPF_S_ALU_AND_K:
321 if (K >= 0xFFFFFF00) {
322 EMIT2(0x24, K & 0xFF); /* and imm8,%al */
323 } else if (K >= 0xFFFF0000) {
324 EMIT2(0x66, 0x25); /* and imm16,%ax */
325 EMIT(K, 2);
326 } else {
327 EMIT1_off32(0x25, K); /* and imm32,%eax */
328 }
329 break;
330 case BPF_S_ALU_OR_X:
331 seen |= SEEN_XREG;
332 EMIT2(0x09, 0xd8); /* or %ebx,%eax */
333 break;
334 case BPF_S_ALU_OR_K:
335 if (is_imm8(K))
336 EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
337 else
338 EMIT1_off32(0x0d, K); /* or imm32,%eax */
339 break;
340 case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
341 case BPF_S_ALU_XOR_X:
342 seen |= SEEN_XREG;
343 EMIT2(0x31, 0xd8); /* xor %ebx,%eax */
344 break;
345 case BPF_S_ALU_XOR_K: /* A ^= K; */
346 if (K == 0)
347 break;
348 if (is_imm8(K))
349 EMIT3(0x83, 0xf0, K); /* xor imm8,%eax */
350 else
351 EMIT1_off32(0x35, K); /* xor imm32,%eax */
352 break;
353 case BPF_S_ALU_LSH_X: /* A <<= X; */
354 seen |= SEEN_XREG;
355 EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */
356 break;
357 case BPF_S_ALU_LSH_K:
358 if (K == 0)
359 break;
360 else if (K == 1)
361 EMIT2(0xd1, 0xe0); /* shl %eax */
362 else
363 EMIT3(0xc1, 0xe0, K);
364 break;
365 case BPF_S_ALU_RSH_X: /* A >>= X; */
366 seen |= SEEN_XREG;
367 EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */
368 break;
369 case BPF_S_ALU_RSH_K: /* A >>= K; */
370 if (K == 0)
371 break;
372 else if (K == 1)
373 EMIT2(0xd1, 0xe8); /* shr %eax */
374 else
375 EMIT3(0xc1, 0xe8, K);
376 break;
377 case BPF_S_ALU_NEG:
378 EMIT2(0xf7, 0xd8); /* neg %eax */
379 break;
380 case BPF_S_RET_K:
381 if (!K) {
382 if (pc_ret0 == -1)
383 pc_ret0 = i;
384 CLEAR_A();
385 } else {
386 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
387 }
388 /* fallinto */
389 case BPF_S_RET_A:
390 if (seen_or_pass0) {
391 if (i != flen - 1) {
392 EMIT_JMP(cleanup_addr - addrs[i]);
393 break;
394 }
395 if (seen_or_pass0 & SEEN_XREG)
396 EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */
397 EMIT1(0xc9); /* leaveq */
398 }
399 EMIT1(0xc3); /* ret */
400 break;
401 case BPF_S_MISC_TAX: /* X = A */
402 seen |= SEEN_XREG;
403 EMIT2(0x89, 0xc3); /* mov %eax,%ebx */
404 break;
405 case BPF_S_MISC_TXA: /* A = X */
406 seen |= SEEN_XREG;
407 EMIT2(0x89, 0xd8); /* mov %ebx,%eax */
408 break;
409 case BPF_S_LD_IMM: /* A = K */
410 if (!K)
411 CLEAR_A();
412 else
413 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
414 break;
415 case BPF_S_LDX_IMM: /* X = K */
416 seen |= SEEN_XREG;
417 if (!K)
418 CLEAR_X();
419 else
420 EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
421 break;
422 case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
423 seen |= SEEN_MEM;
424 EMIT3(0x8b, 0x45, 0xf0 - K*4);
425 break;
426 case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
427 seen |= SEEN_XREG | SEEN_MEM;
428 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
429 break;
430 case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
431 seen |= SEEN_MEM;
432 EMIT3(0x89, 0x45, 0xf0 - K*4);
433 break;
434 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
435 seen |= SEEN_XREG | SEEN_MEM;
436 EMIT3(0x89, 0x5d, 0xf0 - K*4);
437 break;
438 case BPF_S_LD_W_LEN: /* A = skb->len; */
439 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
440 if (is_imm8(offsetof(struct sk_buff, len)))
441 /* mov off8(%rdi),%eax */
442 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
443 else {
444 EMIT2(0x8b, 0x87);
445 EMIT(offsetof(struct sk_buff, len), 4);
446 }
447 break;
448 case BPF_S_LDX_W_LEN: /* X = skb->len; */
449 seen |= SEEN_XREG;
450 if (is_imm8(offsetof(struct sk_buff, len)))
451 /* mov off8(%rdi),%ebx */
452 EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
453 else {
454 EMIT2(0x8b, 0x9f);
455 EMIT(offsetof(struct sk_buff, len), 4);
456 }
457 break;
458 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
459 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
460 if (is_imm8(offsetof(struct sk_buff, protocol))) {
461 /* movzwl off8(%rdi),%eax */
462 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
463 } else {
464 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
465 EMIT(offsetof(struct sk_buff, protocol), 4);
466 }
467 EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */
468 break;
469 case BPF_S_ANC_IFINDEX:
470 if (is_imm8(offsetof(struct sk_buff, dev))) {
471 /* movq off8(%rdi),%rax */
472 EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
473 } else {
474 EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
475 EMIT(offsetof(struct sk_buff, dev), 4);
476 }
477 EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */
478 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
479 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
480 EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */
481 EMIT(offsetof(struct net_device, ifindex), 4);
482 break;
483 case BPF_S_ANC_MARK:
484 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
485 if (is_imm8(offsetof(struct sk_buff, mark))) {
486 /* mov off8(%rdi),%eax */
487 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
488 } else {
489 EMIT2(0x8b, 0x87);
490 EMIT(offsetof(struct sk_buff, mark), 4);
491 }
492 break;
493 case BPF_S_ANC_RXHASH:
494 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
495 if (is_imm8(offsetof(struct sk_buff, rxhash))) {
496 /* mov off8(%rdi),%eax */
497 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
498 } else {
499 EMIT2(0x8b, 0x87);
500 EMIT(offsetof(struct sk_buff, rxhash), 4);
501 }
502 break;
503 case BPF_S_ANC_QUEUE:
504 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
505 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
506 /* movzwl off8(%rdi),%eax */
507 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
508 } else {
509 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
510 EMIT(offsetof(struct sk_buff, queue_mapping), 4);
511 }
512 break;
513 case BPF_S_ANC_CPU:
514 #ifdef CONFIG_SMP
515 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
516 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
517 #else
518 CLEAR_A();
519 #endif
520 break;
521 case BPF_S_ANC_VLAN_TAG:
522 case BPF_S_ANC_VLAN_TAG_PRESENT:
523 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
524 if (is_imm8(offsetof(struct sk_buff, vlan_tci))) {
525 /* movzwl off8(%rdi),%eax */
526 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, vlan_tci));
527 } else {
528 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
529 EMIT(offsetof(struct sk_buff, vlan_tci), 4);
530 }
531 BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
532 if (filter[i].code == BPF_S_ANC_VLAN_TAG) {
533 EMIT3(0x80, 0xe4, 0xef); /* and $0xef,%ah */
534 } else {
535 EMIT3(0xc1, 0xe8, 0x0c); /* shr $0xc,%eax */
536 EMIT3(0x83, 0xe0, 0x01); /* and $0x1,%eax */
537 }
538 break;
539 case BPF_S_LD_W_ABS:
540 func = CHOOSE_LOAD_FUNC(K, sk_load_word);
541 common_load: seen |= SEEN_DATAREF;
542 t_offset = func - (image + addrs[i]);
543 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
544 EMIT1_off32(0xe8, t_offset); /* call */
545 break;
546 case BPF_S_LD_H_ABS:
547 func = CHOOSE_LOAD_FUNC(K, sk_load_half);
548 goto common_load;
549 case BPF_S_LD_B_ABS:
550 func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
551 goto common_load;
552 case BPF_S_LDX_B_MSH:
553 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
554 seen |= SEEN_DATAREF | SEEN_XREG;
555 t_offset = func - (image + addrs[i]);
556 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
557 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
558 break;
559 case BPF_S_LD_W_IND:
560 func = sk_load_word;
561 common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG;
562 t_offset = func - (image + addrs[i]);
563 if (K) {
564 if (is_imm8(K)) {
565 EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */
566 } else {
567 EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */
568 EMIT(K, 4);
569 }
570 } else {
571 EMIT2(0x89,0xde); /* mov %ebx,%esi */
572 }
573 EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */
574 break;
575 case BPF_S_LD_H_IND:
576 func = sk_load_half;
577 goto common_load_ind;
578 case BPF_S_LD_B_IND:
579 func = sk_load_byte;
580 goto common_load_ind;
581 case BPF_S_JMP_JA:
582 t_offset = addrs[i + K] - addrs[i];
583 EMIT_JMP(t_offset);
584 break;
585 COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
586 COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
587 COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
588 COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
589 COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
590 COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
591 COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
592 COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
593
594 cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
595 t_offset = addrs[i + filter[i].jt] - addrs[i];
596
597 /* same targets, can avoid doing the test :) */
598 if (filter[i].jt == filter[i].jf) {
599 EMIT_JMP(t_offset);
600 break;
601 }
602
603 switch (filter[i].code) {
604 case BPF_S_JMP_JGT_X:
605 case BPF_S_JMP_JGE_X:
606 case BPF_S_JMP_JEQ_X:
607 seen |= SEEN_XREG;
608 EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
609 break;
610 case BPF_S_JMP_JSET_X:
611 seen |= SEEN_XREG;
612 EMIT2(0x85, 0xd8); /* test %ebx,%eax */
613 break;
614 case BPF_S_JMP_JEQ_K:
615 if (K == 0) {
616 EMIT2(0x85, 0xc0); /* test %eax,%eax */
617 break;
618 }
619 case BPF_S_JMP_JGT_K:
620 case BPF_S_JMP_JGE_K:
621 if (K <= 127)
622 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
623 else
624 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
625 break;
626 case BPF_S_JMP_JSET_K:
627 if (K <= 0xFF)
628 EMIT2(0xa8, K); /* test imm8,%al */
629 else if (!(K & 0xFFFF00FF))
630 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
631 else if (K <= 0xFFFF) {
632 EMIT2(0x66, 0xa9); /* test imm16,%ax */
633 EMIT(K, 2);
634 } else {
635 EMIT1_off32(0xa9, K); /* test imm32,%eax */
636 }
637 break;
638 }
639 if (filter[i].jt != 0) {
640 if (filter[i].jf && f_offset)
641 t_offset += is_near(f_offset) ? 2 : 5;
642 EMIT_COND_JMP(t_op, t_offset);
643 if (filter[i].jf)
644 EMIT_JMP(f_offset);
645 break;
646 }
647 EMIT_COND_JMP(f_op, f_offset);
648 break;
649 default:
650 /* hmm, too complex filter, give up with jit compiler */
651 goto out;
652 }
653 ilen = prog - temp;
654 if (image) {
655 if (unlikely(proglen + ilen > oldproglen)) {
656 pr_err("bpb_jit_compile fatal error\n");
657 kfree(addrs);
658 module_free(NULL, image);
659 return;
660 }
661 memcpy(image + proglen, temp, ilen);
662 }
663 proglen += ilen;
664 addrs[i] = proglen;
665 prog = temp;
666 }
667 /* last bpf instruction is always a RET :
668 * use it to give the cleanup instruction(s) addr
669 */
670 cleanup_addr = proglen - 1; /* ret */
671 if (seen_or_pass0)
672 cleanup_addr -= 1; /* leaveq */
673 if (seen_or_pass0 & SEEN_XREG)
674 cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
675
676 if (image) {
677 if (proglen != oldproglen)
678 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
679 break;
680 }
681 if (proglen == oldproglen) {
682 image = module_alloc(max_t(unsigned int,
683 proglen,
684 sizeof(struct work_struct)));
685 if (!image)
686 goto out;
687 }
688 oldproglen = proglen;
689 }
690 if (bpf_jit_enable > 1)
691 pr_err("flen=%d proglen=%u pass=%d image=%p\n",
692 flen, proglen, pass, image);
693
694 if (image) {
695 if (bpf_jit_enable > 1)
696 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
697 16, 1, image, proglen, false);
698
699 bpf_flush_icache(image, image + proglen);
700
701 fp->bpf_func = (void *)image;
702 }
703 out:
704 kfree(addrs);
705 return;
706 }
707
708 static void jit_free_defer(struct work_struct *arg)
709 {
710 module_free(NULL, arg);
711 }
712
713 /* run from softirq, we must use a work_struct to call
714 * module_free() from process context
715 */
716 void bpf_jit_free(struct sk_filter *fp)
717 {
718 if (fp->bpf_func != sk_run_filter) {
719 struct work_struct *work = (struct work_struct *)fp->bpf_func;
720
721 INIT_WORK(work, jit_free_defer);
722 schedule_work(work);
723 }
724 }
CRIS linux kernel tree