?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Linux 3.11-rc3
[cris-mirror.git] / arch / s390 / net / bpf_jit_comp.c
blobd5f10a43a58fb145b5514b897121fd9471fdabb2
1 /*
2 * BPF Jit compiler for s390.
3 *
4 * Copyright IBM Corp. 2012
5 *
6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
7 */
8 #include <linux/moduleloader.h>
9 #include <linux/netdevice.h>
10 #include <linux/if_vlan.h>
11 #include <linux/filter.h>
12 #include <linux/random.h>
13 #include <linux/init.h>
14 #include <asm/cacheflush.h>
15 #include <asm/processor.h>
16 #include <asm/facility.h>
17
18 /*
19 * Conventions:
20 * %r2 = skb pointer
21 * %r3 = offset parameter
22 * %r4 = scratch register / length parameter
23 * %r5 = BPF A accumulator
24 * %r8 = return address
25 * %r9 = save register for skb pointer
26 * %r10 = skb->data
27 * %r11 = skb->len - skb->data_len (headlen)
28 * %r12 = BPF X accumulator
29 * %r13 = literal pool pointer
30 * 0(%r15) - 63(%r15) scratch memory array with BPF_MEMWORDS
31 */
32 int bpf_jit_enable __read_mostly;
33
34 /*
35 * assembly code in arch/x86/net/bpf_jit.S
36 */
37 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
38 extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
39
40 struct bpf_jit {
41 unsigned int seen;
42 u8 *start;
43 u8 *prg;
44 u8 *mid;
45 u8 *lit;
46 u8 *end;
47 u8 *base_ip;
48 u8 *ret0_ip;
49 u8 *exit_ip;
50 unsigned int off_load_word;
51 unsigned int off_load_half;
52 unsigned int off_load_byte;
53 unsigned int off_load_bmsh;
54 unsigned int off_load_iword;
55 unsigned int off_load_ihalf;
56 unsigned int off_load_ibyte;
57 };
58
59 #define BPF_SIZE_MAX 4096 /* Max size for program */
60
61 #define SEEN_DATAREF 1 /* might call external helpers */
62 #define SEEN_XREG 2 /* ebx is used */
63 #define SEEN_MEM 4 /* use mem[] for temporary storage */
64 #define SEEN_RET0 8 /* pc_ret0 points to a valid return 0 */
65 #define SEEN_LITERAL 16 /* code uses literals */
66 #define SEEN_LOAD_WORD 32 /* code uses sk_load_word */
67 #define SEEN_LOAD_HALF 64 /* code uses sk_load_half */
68 #define SEEN_LOAD_BYTE 128 /* code uses sk_load_byte */
69 #define SEEN_LOAD_BMSH 256 /* code uses sk_load_byte_msh */
70 #define SEEN_LOAD_IWORD 512 /* code uses sk_load_word_ind */
71 #define SEEN_LOAD_IHALF 1024 /* code uses sk_load_half_ind */
72 #define SEEN_LOAD_IBYTE 2048 /* code uses sk_load_byte_ind */
73
74 #define EMIT2(op) \
75 ({ \
76 if (jit->prg + 2 <= jit->mid) \
77 *(u16 *) jit->prg = op; \
78 jit->prg += 2; \
79 })
80
81 #define EMIT4(op) \
82 ({ \
83 if (jit->prg + 4 <= jit->mid) \
84 *(u32 *) jit->prg = op; \
85 jit->prg += 4; \
86 })
87
88 #define EMIT4_DISP(op, disp) \
89 ({ \
90 unsigned int __disp = (disp) & 0xfff; \
91 EMIT4(op | __disp); \
92 })
93
94 #define EMIT4_IMM(op, imm) \
95 ({ \
96 unsigned int __imm = (imm) & 0xffff; \
97 EMIT4(op | __imm); \
98 })
99
100 #define EMIT4_PCREL(op, pcrel) \
101 ({ \
102 long __pcrel = ((pcrel) >> 1) & 0xffff; \
103 EMIT4(op | __pcrel); \
104 })
105
106 #define EMIT6(op1, op2) \
107 ({ \
108 if (jit->prg + 6 <= jit->mid) { \
109 *(u32 *) jit->prg = op1; \
110 *(u16 *) (jit->prg + 4) = op2; \
111 } \
112 jit->prg += 6; \
113 })
114
115 #define EMIT6_DISP(op1, op2, disp) \
116 ({ \
117 unsigned int __disp = (disp) & 0xfff; \
118 EMIT6(op1 | __disp, op2); \
119 })
120
121 #define EMIT6_IMM(op, imm) \
122 ({ \
123 unsigned int __imm = (imm); \
124 EMIT6(op | (__imm >> 16), __imm & 0xffff); \
125 })
126
127 #define EMIT_CONST(val) \
128 ({ \
129 unsigned int ret; \
130 ret = (unsigned int) (jit->lit - jit->base_ip); \
131 jit->seen |= SEEN_LITERAL; \
132 if (jit->lit + 4 <= jit->end) \
133 *(u32 *) jit->lit = val; \
134 jit->lit += 4; \
135 ret; \
136 })
137
138 #define EMIT_FN_CONST(bit, fn) \
139 ({ \
140 unsigned int ret; \
141 ret = (unsigned int) (jit->lit - jit->base_ip); \
142 if (jit->seen & bit) { \
143 jit->seen |= SEEN_LITERAL; \
144 if (jit->lit + 8 <= jit->end) \
145 *(void **) jit->lit = fn; \
146 jit->lit += 8; \
147 } \
148 ret; \
149 })
150
151 static void bpf_jit_prologue(struct bpf_jit *jit)
152 {
153 /* Save registers and create stack frame if necessary */
154 if (jit->seen & SEEN_DATAREF) {
155 /* stmg %r8,%r15,88(%r15) */
156 EMIT6(0xeb8ff058, 0x0024);
157 /* lgr %r14,%r15 */
158 EMIT4(0xb90400ef);
159 /* ahi %r15,<offset> */
160 EMIT4_IMM(0xa7fa0000, (jit->seen & SEEN_MEM) ? -112 : -80);
161 /* stg %r14,152(%r15) */
162 EMIT6(0xe3e0f098, 0x0024);
163 } else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
164 /* stmg %r12,%r13,120(%r15) */
165 EMIT6(0xebcdf078, 0x0024);
166 else if (jit->seen & SEEN_XREG)
167 /* stg %r12,120(%r15) */
168 EMIT6(0xe3c0f078, 0x0024);
169 else if (jit->seen & SEEN_LITERAL)
170 /* stg %r13,128(%r15) */
171 EMIT6(0xe3d0f080, 0x0024);
172
173 /* Setup literal pool */
174 if (jit->seen & SEEN_LITERAL) {
175 /* basr %r13,0 */
176 EMIT2(0x0dd0);
177 jit->base_ip = jit->prg;
178 }
179 jit->off_load_word = EMIT_FN_CONST(SEEN_LOAD_WORD, sk_load_word);
180 jit->off_load_half = EMIT_FN_CONST(SEEN_LOAD_HALF, sk_load_half);
181 jit->off_load_byte = EMIT_FN_CONST(SEEN_LOAD_BYTE, sk_load_byte);
182 jit->off_load_bmsh = EMIT_FN_CONST(SEEN_LOAD_BMSH, sk_load_byte_msh);
183 jit->off_load_iword = EMIT_FN_CONST(SEEN_LOAD_IWORD, sk_load_word_ind);
184 jit->off_load_ihalf = EMIT_FN_CONST(SEEN_LOAD_IHALF, sk_load_half_ind);
185 jit->off_load_ibyte = EMIT_FN_CONST(SEEN_LOAD_IBYTE, sk_load_byte_ind);
186
187 /* Filter needs to access skb data */
188 if (jit->seen & SEEN_DATAREF) {
189 /* l %r11,<len>(%r2) */
190 EMIT4_DISP(0x58b02000, offsetof(struct sk_buff, len));
191 /* s %r11,<data_len>(%r2) */
192 EMIT4_DISP(0x5bb02000, offsetof(struct sk_buff, data_len));
193 /* lg %r10,<data>(%r2) */
194 EMIT6_DISP(0xe3a02000, 0x0004,
195 offsetof(struct sk_buff, data));
196 }
197 }
198
199 static void bpf_jit_epilogue(struct bpf_jit *jit)
200 {
201 /* Return 0 */
202 if (jit->seen & SEEN_RET0) {
203 jit->ret0_ip = jit->prg;
204 /* lghi %r2,0 */
205 EMIT4(0xa7290000);
206 }
207 jit->exit_ip = jit->prg;
208 /* Restore registers */
209 if (jit->seen & SEEN_DATAREF)
210 /* lmg %r8,%r15,<offset>(%r15) */
211 EMIT6_DISP(0xeb8ff000, 0x0004,
212 (jit->seen & SEEN_MEM) ? 200 : 168);
213 else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
214 /* lmg %r12,%r13,120(%r15) */
215 EMIT6(0xebcdf078, 0x0004);
216 else if (jit->seen & SEEN_XREG)
217 /* lg %r12,120(%r15) */
218 EMIT6(0xe3c0f078, 0x0004);
219 else if (jit->seen & SEEN_LITERAL)
220 /* lg %r13,128(%r15) */
221 EMIT6(0xe3d0f080, 0x0004);
222 /* br %r14 */
223 EMIT2(0x07fe);
224 }
225
226 /* Helper to find the offset of pkt_type in sk_buff
227 * Make sure its still a 3bit field starting at the MSBs within a byte.
228 */
229 #define PKT_TYPE_MAX 0xe0
230 static int pkt_type_offset;
231
232 static int __init bpf_pkt_type_offset_init(void)
233 {
234 struct sk_buff skb_probe = {
235 .pkt_type = ~0,
236 };
237 char *ct = (char *)&skb_probe;
238 int off;
239
240 pkt_type_offset = -1;
241 for (off = 0; off < sizeof(struct sk_buff); off++) {
242 if (!ct[off])
243 continue;
244 if (ct[off] == PKT_TYPE_MAX)
245 pkt_type_offset = off;
246 else {
247 /* Found non matching bit pattern, fix needed. */
248 WARN_ON_ONCE(1);
249 pkt_type_offset = -1;
250 return -1;
251 }
252 }
253 return 0;
254 }
255 device_initcall(bpf_pkt_type_offset_init);
256
257 /*
258 * make sure we dont leak kernel information to user
259 */
260 static void bpf_jit_noleaks(struct bpf_jit *jit, struct sock_filter *filter)
261 {
262 /* Clear temporary memory if (seen & SEEN_MEM) */
263 if (jit->seen & SEEN_MEM)
264 /* xc 0(64,%r15),0(%r15) */
265 EMIT6(0xd73ff000, 0xf000);
266 /* Clear X if (seen & SEEN_XREG) */
267 if (jit->seen & SEEN_XREG)
268 /* lhi %r12,0 */
269 EMIT4(0xa7c80000);
270 /* Clear A if the first register does not set it. */
271 switch (filter[0].code) {
272 case BPF_S_LD_W_ABS:
273 case BPF_S_LD_H_ABS:
274 case BPF_S_LD_B_ABS:
275 case BPF_S_LD_W_LEN:
276 case BPF_S_LD_W_IND:
277 case BPF_S_LD_H_IND:
278 case BPF_S_LD_B_IND:
279 case BPF_S_LDX_B_MSH:
280 case BPF_S_LD_IMM:
281 case BPF_S_LD_MEM:
282 case BPF_S_MISC_TXA:
283 case BPF_S_ANC_PROTOCOL:
284 case BPF_S_ANC_PKTTYPE:
285 case BPF_S_ANC_IFINDEX:
286 case BPF_S_ANC_MARK:
287 case BPF_S_ANC_QUEUE:
288 case BPF_S_ANC_HATYPE:
289 case BPF_S_ANC_RXHASH:
290 case BPF_S_ANC_CPU:
291 case BPF_S_ANC_VLAN_TAG:
292 case BPF_S_ANC_VLAN_TAG_PRESENT:
293 case BPF_S_RET_K:
294 /* first instruction sets A register */
295 break;
296 default: /* A = 0 */
297 /* lhi %r5,0 */
298 EMIT4(0xa7580000);
299 }
300 }
301
302 static int bpf_jit_insn(struct bpf_jit *jit, struct sock_filter *filter,
303 unsigned int *addrs, int i, int last)
304 {
305 unsigned int K;
306 int offset;
307 unsigned int mask;
308
309 K = filter->k;
310 switch (filter->code) {
311 case BPF_S_ALU_ADD_X: /* A += X */
312 jit->seen |= SEEN_XREG;
313 /* ar %r5,%r12 */
314 EMIT2(0x1a5c);
315 break;
316 case BPF_S_ALU_ADD_K: /* A += K */
317 if (!K)
318 break;
319 if (K <= 16383)
320 /* ahi %r5,<K> */
321 EMIT4_IMM(0xa75a0000, K);
322 else if (test_facility(21))
323 /* alfi %r5,<K> */
324 EMIT6_IMM(0xc25b0000, K);
325 else
326 /* a %r5,<d(K)>(%r13) */
327 EMIT4_DISP(0x5a50d000, EMIT_CONST(K));
328 break;
329 case BPF_S_ALU_SUB_X: /* A -= X */
330 jit->seen |= SEEN_XREG;
331 /* sr %r5,%r12 */
332 EMIT2(0x1b5c);
333 break;
334 case BPF_S_ALU_SUB_K: /* A -= K */
335 if (!K)
336 break;
337 if (K <= 16384)
338 /* ahi %r5,-K */
339 EMIT4_IMM(0xa75a0000, -K);
340 else if (test_facility(21))
341 /* alfi %r5,-K */
342 EMIT6_IMM(0xc25b0000, -K);
343 else
344 /* s %r5,<d(K)>(%r13) */
345 EMIT4_DISP(0x5b50d000, EMIT_CONST(K));
346 break;
347 case BPF_S_ALU_MUL_X: /* A *= X */
348 jit->seen |= SEEN_XREG;
349 /* msr %r5,%r12 */
350 EMIT4(0xb252005c);
351 break;
352 case BPF_S_ALU_MUL_K: /* A *= K */
353 if (K <= 16383)
354 /* mhi %r5,K */
355 EMIT4_IMM(0xa75c0000, K);
356 else if (test_facility(34))
357 /* msfi %r5,<K> */
358 EMIT6_IMM(0xc2510000, K);
359 else
360 /* ms %r5,<d(K)>(%r13) */
361 EMIT4_DISP(0x7150d000, EMIT_CONST(K));
362 break;
363 case BPF_S_ALU_DIV_X: /* A /= X */
364 jit->seen |= SEEN_XREG | SEEN_RET0;
365 /* ltr %r12,%r12 */
366 EMIT2(0x12cc);
367 /* jz <ret0> */
368 EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
369 /* lhi %r4,0 */
370 EMIT4(0xa7480000);
371 /* dr %r4,%r12 */
372 EMIT2(0x1d4c);
373 break;
374 case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K) */
375 /* m %r4,<d(K)>(%r13) */
376 EMIT4_DISP(0x5c40d000, EMIT_CONST(K));
377 /* lr %r5,%r4 */
378 EMIT2(0x1854);
379 break;
380 case BPF_S_ALU_MOD_X: /* A %= X */
381 jit->seen |= SEEN_XREG | SEEN_RET0;
382 /* ltr %r12,%r12 */
383 EMIT2(0x12cc);
384 /* jz <ret0> */
385 EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
386 /* lhi %r4,0 */
387 EMIT4(0xa7480000);
388 /* dr %r4,%r12 */
389 EMIT2(0x1d4c);
390 /* lr %r5,%r4 */
391 EMIT2(0x1854);
392 break;
393 case BPF_S_ALU_MOD_K: /* A %= K */
394 /* lhi %r4,0 */
395 EMIT4(0xa7480000);
396 /* d %r4,<d(K)>(%r13) */
397 EMIT4_DISP(0x5d40d000, EMIT_CONST(K));
398 /* lr %r5,%r4 */
399 EMIT2(0x1854);
400 break;
401 case BPF_S_ALU_AND_X: /* A &= X */
402 jit->seen |= SEEN_XREG;
403 /* nr %r5,%r12 */
404 EMIT2(0x145c);
405 break;
406 case BPF_S_ALU_AND_K: /* A &= K */
407 if (test_facility(21))
408 /* nilf %r5,<K> */
409 EMIT6_IMM(0xc05b0000, K);
410 else
411 /* n %r5,<d(K)>(%r13) */
412 EMIT4_DISP(0x5450d000, EMIT_CONST(K));
413 break;
414 case BPF_S_ALU_OR_X: /* A |= X */
415 jit->seen |= SEEN_XREG;
416 /* or %r5,%r12 */
417 EMIT2(0x165c);
418 break;
419 case BPF_S_ALU_OR_K: /* A |= K */
420 if (test_facility(21))
421 /* oilf %r5,<K> */
422 EMIT6_IMM(0xc05d0000, K);
423 else
424 /* o %r5,<d(K)>(%r13) */
425 EMIT4_DISP(0x5650d000, EMIT_CONST(K));
426 break;
427 case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
428 case BPF_S_ALU_XOR_X:
429 jit->seen |= SEEN_XREG;
430 /* xr %r5,%r12 */
431 EMIT2(0x175c);
432 break;
433 case BPF_S_ALU_XOR_K: /* A ^= K */
434 if (!K)
435 break;
436 /* x %r5,<d(K)>(%r13) */
437 EMIT4_DISP(0x5750d000, EMIT_CONST(K));
438 break;
439 case BPF_S_ALU_LSH_X: /* A <<= X; */
440 jit->seen |= SEEN_XREG;
441 /* sll %r5,0(%r12) */
442 EMIT4(0x8950c000);
443 break;
444 case BPF_S_ALU_LSH_K: /* A <<= K */
445 if (K == 0)
446 break;
447 /* sll %r5,K */
448 EMIT4_DISP(0x89500000, K);
449 break;
450 case BPF_S_ALU_RSH_X: /* A >>= X; */
451 jit->seen |= SEEN_XREG;
452 /* srl %r5,0(%r12) */
453 EMIT4(0x8850c000);
454 break;
455 case BPF_S_ALU_RSH_K: /* A >>= K; */
456 if (K == 0)
457 break;
458 /* srl %r5,K */
459 EMIT4_DISP(0x88500000, K);
460 break;
461 case BPF_S_ALU_NEG: /* A = -A */
462 /* lnr %r5,%r5 */
463 EMIT2(0x1155);
464 break;
465 case BPF_S_JMP_JA: /* ip += K */
466 offset = addrs[i + K] + jit->start - jit->prg;
467 EMIT4_PCREL(0xa7f40000, offset);
468 break;
469 case BPF_S_JMP_JGT_K: /* ip += (A > K) ? jt : jf */
470 mask = 0x200000; /* jh */
471 goto kbranch;
472 case BPF_S_JMP_JGE_K: /* ip += (A >= K) ? jt : jf */
473 mask = 0xa00000; /* jhe */
474 goto kbranch;
475 case BPF_S_JMP_JEQ_K: /* ip += (A == K) ? jt : jf */
476 mask = 0x800000; /* je */
477 kbranch: /* Emit compare if the branch targets are different */
478 if (filter->jt != filter->jf) {
479 if (K <= 16383)
480 /* chi %r5,<K> */
481 EMIT4_IMM(0xa75e0000, K);
482 else if (test_facility(21))
483 /* clfi %r5,<K> */
484 EMIT6_IMM(0xc25f0000, K);
485 else
486 /* c %r5,<d(K)>(%r13) */
487 EMIT4_DISP(0x5950d000, EMIT_CONST(K));
488 }
489 branch: if (filter->jt == filter->jf) {
490 if (filter->jt == 0)
491 break;
492 /* j <jt> */
493 offset = addrs[i + filter->jt] + jit->start - jit->prg;
494 EMIT4_PCREL(0xa7f40000, offset);
495 break;
496 }
497 if (filter->jt != 0) {
498 /* brc <mask>,<jt> */
499 offset = addrs[i + filter->jt] + jit->start - jit->prg;
500 EMIT4_PCREL(0xa7040000 | mask, offset);
501 }
502 if (filter->jf != 0) {
503 /* brc <mask^15>,<jf> */
504 offset = addrs[i + filter->jf] + jit->start - jit->prg;
505 EMIT4_PCREL(0xa7040000 | (mask ^ 0xf00000), offset);
506 }
507 break;
508 case BPF_S_JMP_JSET_K: /* ip += (A & K) ? jt : jf */
509 mask = 0x700000; /* jnz */
510 /* Emit test if the branch targets are different */
511 if (filter->jt != filter->jf) {
512 if (K > 65535) {
513 /* lr %r4,%r5 */
514 EMIT2(0x1845);
515 /* n %r4,<d(K)>(%r13) */
516 EMIT4_DISP(0x5440d000, EMIT_CONST(K));
517 } else
518 /* tmll %r5,K */
519 EMIT4_IMM(0xa7510000, K);
520 }
521 goto branch;
522 case BPF_S_JMP_JGT_X: /* ip += (A > X) ? jt : jf */
523 mask = 0x200000; /* jh */
524 goto xbranch;
525 case BPF_S_JMP_JGE_X: /* ip += (A >= X) ? jt : jf */
526 mask = 0xa00000; /* jhe */
527 goto xbranch;
528 case BPF_S_JMP_JEQ_X: /* ip += (A == X) ? jt : jf */
529 mask = 0x800000; /* je */
530 xbranch: /* Emit compare if the branch targets are different */
531 if (filter->jt != filter->jf) {
532 jit->seen |= SEEN_XREG;
533 /* cr %r5,%r12 */
534 EMIT2(0x195c);
535 }
536 goto branch;
537 case BPF_S_JMP_JSET_X: /* ip += (A & X) ? jt : jf */
538 mask = 0x700000; /* jnz */
539 /* Emit test if the branch targets are different */
540 if (filter->jt != filter->jf) {
541 jit->seen |= SEEN_XREG;
542 /* lr %r4,%r5 */
543 EMIT2(0x1845);
544 /* nr %r4,%r12 */
545 EMIT2(0x144c);
546 }
547 goto branch;
548 case BPF_S_LD_W_ABS: /* A = *(u32 *) (skb->data+K) */
549 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_WORD;
550 offset = jit->off_load_word;
551 goto load_abs;
552 case BPF_S_LD_H_ABS: /* A = *(u16 *) (skb->data+K) */
553 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_HALF;
554 offset = jit->off_load_half;
555 goto load_abs;
556 case BPF_S_LD_B_ABS: /* A = *(u8 *) (skb->data+K) */
557 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_BYTE;
558 offset = jit->off_load_byte;
559 load_abs: if ((int) K < 0)
560 goto out;
561 call_fn: /* lg %r1,<d(function)>(%r13) */
562 EMIT6_DISP(0xe310d000, 0x0004, offset);
563 /* l %r3,<d(K)>(%r13) */
564 EMIT4_DISP(0x5830d000, EMIT_CONST(K));
565 /* basr %r8,%r1 */
566 EMIT2(0x0d81);
567 /* jnz <ret0> */
568 EMIT4_PCREL(0xa7740000, (jit->ret0_ip - jit->prg));
569 break;
570 case BPF_S_LD_W_IND: /* A = *(u32 *) (skb->data+K+X) */
571 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IWORD;
572 offset = jit->off_load_iword;
573 goto call_fn;
574 case BPF_S_LD_H_IND: /* A = *(u16 *) (skb->data+K+X) */
575 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IHALF;
576 offset = jit->off_load_ihalf;
577 goto call_fn;
578 case BPF_S_LD_B_IND: /* A = *(u8 *) (skb->data+K+X) */
579 jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IBYTE;
580 offset = jit->off_load_ibyte;
581 goto call_fn;
582 case BPF_S_LDX_B_MSH:
583 /* X = (*(u8 *)(skb->data+K) & 0xf) << 2 */
584 jit->seen |= SEEN_RET0;
585 if ((int) K < 0) {
586 /* j <ret0> */
587 EMIT4_PCREL(0xa7f40000, (jit->ret0_ip - jit->prg));
588 break;
589 }
590 jit->seen |= SEEN_DATAREF | SEEN_LOAD_BMSH;
591 offset = jit->off_load_bmsh;
592 goto call_fn;
593 case BPF_S_LD_W_LEN: /* A = skb->len; */
594 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
595 /* l %r5,<d(len)>(%r2) */
596 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, len));
597 break;
598 case BPF_S_LDX_W_LEN: /* X = skb->len; */
599 jit->seen |= SEEN_XREG;
600 /* l %r12,<d(len)>(%r2) */
601 EMIT4_DISP(0x58c02000, offsetof(struct sk_buff, len));
602 break;
603 case BPF_S_LD_IMM: /* A = K */
604 if (K <= 16383)
605 /* lhi %r5,K */
606 EMIT4_IMM(0xa7580000, K);
607 else if (test_facility(21))
608 /* llilf %r5,<K> */
609 EMIT6_IMM(0xc05f0000, K);
610 else
611 /* l %r5,<d(K)>(%r13) */
612 EMIT4_DISP(0x5850d000, EMIT_CONST(K));
613 break;
614 case BPF_S_LDX_IMM: /* X = K */
615 jit->seen |= SEEN_XREG;
616 if (K <= 16383)
617 /* lhi %r12,<K> */
618 EMIT4_IMM(0xa7c80000, K);
619 else if (test_facility(21))
620 /* llilf %r12,<K> */
621 EMIT6_IMM(0xc0cf0000, K);
622 else
623 /* l %r12,<d(K)>(%r13) */
624 EMIT4_DISP(0x58c0d000, EMIT_CONST(K));
625 break;
626 case BPF_S_LD_MEM: /* A = mem[K] */
627 jit->seen |= SEEN_MEM;
628 /* l %r5,<K>(%r15) */
629 EMIT4_DISP(0x5850f000,
630 (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
631 break;
632 case BPF_S_LDX_MEM: /* X = mem[K] */
633 jit->seen |= SEEN_XREG | SEEN_MEM;
634 /* l %r12,<K>(%r15) */
635 EMIT4_DISP(0x58c0f000,
636 (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
637 break;
638 case BPF_S_MISC_TAX: /* X = A */
639 jit->seen |= SEEN_XREG;
640 /* lr %r12,%r5 */
641 EMIT2(0x18c5);
642 break;
643 case BPF_S_MISC_TXA: /* A = X */
644 jit->seen |= SEEN_XREG;
645 /* lr %r5,%r12 */
646 EMIT2(0x185c);
647 break;
648 case BPF_S_RET_K:
649 if (K == 0) {
650 jit->seen |= SEEN_RET0;
651 if (last)
652 break;
653 /* j <ret0> */
654 EMIT4_PCREL(0xa7f40000, jit->ret0_ip - jit->prg);
655 } else {
656 if (K <= 16383)
657 /* lghi %r2,K */
658 EMIT4_IMM(0xa7290000, K);
659 else
660 /* llgf %r2,<K>(%r13) */
661 EMIT6_DISP(0xe320d000, 0x0016, EMIT_CONST(K));
662 /* j <exit> */
663 if (last && !(jit->seen & SEEN_RET0))
664 break;
665 EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
666 }
667 break;
668 case BPF_S_RET_A:
669 /* llgfr %r2,%r5 */
670 EMIT4(0xb9160025);
671 /* j <exit> */
672 EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
673 break;
674 case BPF_S_ST: /* mem[K] = A */
675 jit->seen |= SEEN_MEM;
676 /* st %r5,<K>(%r15) */
677 EMIT4_DISP(0x5050f000,
678 (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
679 break;
680 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
681 jit->seen |= SEEN_XREG | SEEN_MEM;
682 /* st %r12,<K>(%r15) */
683 EMIT4_DISP(0x50c0f000,
684 (jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
685 break;
686 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
687 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
688 /* lhi %r5,0 */
689 EMIT4(0xa7580000);
690 /* icm %r5,3,<d(protocol)>(%r2) */
691 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, protocol));
692 break;
693 case BPF_S_ANC_IFINDEX: /* if (!skb->dev) return 0;
694 * A = skb->dev->ifindex */
695 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
696 jit->seen |= SEEN_RET0;
697 /* lg %r1,<d(dev)>(%r2) */
698 EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
699 /* ltgr %r1,%r1 */
700 EMIT4(0xb9020011);
701 /* jz <ret0> */
702 EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
703 /* l %r5,<d(ifindex)>(%r1) */
704 EMIT4_DISP(0x58501000, offsetof(struct net_device, ifindex));
705 break;
706 case BPF_S_ANC_MARK: /* A = skb->mark */
707 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
708 /* l %r5,<d(mark)>(%r2) */
709 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, mark));
710 break;
711 case BPF_S_ANC_QUEUE: /* A = skb->queue_mapping */
712 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
713 /* lhi %r5,0 */
714 EMIT4(0xa7580000);
715 /* icm %r5,3,<d(queue_mapping)>(%r2) */
716 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, queue_mapping));
717 break;
718 case BPF_S_ANC_HATYPE: /* if (!skb->dev) return 0;
719 * A = skb->dev->type */
720 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
721 jit->seen |= SEEN_RET0;
722 /* lg %r1,<d(dev)>(%r2) */
723 EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
724 /* ltgr %r1,%r1 */
725 EMIT4(0xb9020011);
726 /* jz <ret0> */
727 EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
728 /* lhi %r5,0 */
729 EMIT4(0xa7580000);
730 /* icm %r5,3,<d(type)>(%r1) */
731 EMIT4_DISP(0xbf531000, offsetof(struct net_device, type));
732 break;
733 case BPF_S_ANC_RXHASH: /* A = skb->rxhash */
734 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
735 /* l %r5,<d(rxhash)>(%r2) */
736 EMIT4_DISP(0x58502000, offsetof(struct sk_buff, rxhash));
737 break;
738 case BPF_S_ANC_VLAN_TAG:
739 case BPF_S_ANC_VLAN_TAG_PRESENT:
740 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
741 BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
742 /* lhi %r5,0 */
743 EMIT4(0xa7580000);
744 /* icm %r5,3,<d(vlan_tci)>(%r2) */
745 EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, vlan_tci));
746 if (filter->code == BPF_S_ANC_VLAN_TAG) {
747 /* nill %r5,0xefff */
748 EMIT4_IMM(0xa5570000, ~VLAN_TAG_PRESENT);
749 } else {
750 /* nill %r5,0x1000 */
751 EMIT4_IMM(0xa5570000, VLAN_TAG_PRESENT);
752 /* srl %r5,12 */
753 EMIT4_DISP(0x88500000, 12);
754 }
755 break;
756 case BPF_S_ANC_PKTTYPE:
757 if (pkt_type_offset < 0)
758 goto out;
759 /* lhi %r5,0 */
760 EMIT4(0xa7580000);
761 /* ic %r5,<d(pkt_type_offset)>(%r2) */
762 EMIT4_DISP(0x43502000, pkt_type_offset);
763 /* srl %r5,5 */
764 EMIT4_DISP(0x88500000, 5);
765 break;
766 case BPF_S_ANC_CPU: /* A = smp_processor_id() */
767 #ifdef CONFIG_SMP
768 /* l %r5,<d(cpu_nr)> */
769 EMIT4_DISP(0x58500000, offsetof(struct _lowcore, cpu_nr));
770 #else
771 /* lhi %r5,0 */
772 EMIT4(0xa7580000);
773 #endif
774 break;
775 default: /* too complex, give up */
776 goto out;
777 }
778 addrs[i] = jit->prg - jit->start;
779 return 0;
780 out:
781 return -1;
782 }
783
784 /*
785 * Note: for security reasons, bpf code will follow a randomly
786 * sized amount of illegal instructions.
787 */
788 struct bpf_binary_header {
789 unsigned int pages;
790 u8 image[];
791 };
792
793 static struct bpf_binary_header *bpf_alloc_binary(unsigned int bpfsize,
794 u8 **image_ptr)
795 {
796 struct bpf_binary_header *header;
797 unsigned int sz, hole;
798
799 /* Most BPF filters are really small, but if some of them fill a page,
800 * allow at least 128 extra bytes for illegal instructions.
801 */
802 sz = round_up(bpfsize + sizeof(*header) + 128, PAGE_SIZE);
803 header = module_alloc(sz);
804 if (!header)
805 return NULL;
806 memset(header, 0, sz);
807 header->pages = sz / PAGE_SIZE;
808 hole = sz - bpfsize + sizeof(*header);
809 /* Insert random number of illegal instructions before BPF code
810 * and make sure the first instruction starts at an even address.
811 */
812 *image_ptr = &header->image[(prandom_u32() % hole) & -2];
813 return header;
814 }
815
816 void bpf_jit_compile(struct sk_filter *fp)
817 {
818 struct bpf_binary_header *header = NULL;
819 unsigned long size, prg_len, lit_len;
820 struct bpf_jit jit, cjit;
821 unsigned int *addrs;
822 int pass, i;
823
824 if (!bpf_jit_enable)
825 return;
826 addrs = kcalloc(fp->len, sizeof(*addrs), GFP_KERNEL);
827 if (addrs == NULL)
828 return;
829 memset(&jit, 0, sizeof(cjit));
830 memset(&cjit, 0, sizeof(cjit));
831
832 for (pass = 0; pass < 10; pass++) {
833 jit.prg = jit.start;
834 jit.lit = jit.mid;
835
836 bpf_jit_prologue(&jit);
837 bpf_jit_noleaks(&jit, fp->insns);
838 for (i = 0; i < fp->len; i++) {
839 if (bpf_jit_insn(&jit, fp->insns + i, addrs, i,
840 i == fp->len - 1))
841 goto out;
842 }
843 bpf_jit_epilogue(&jit);
844 if (jit.start) {
845 WARN_ON(jit.prg > cjit.prg || jit.lit > cjit.lit);
846 if (memcmp(&jit, &cjit, sizeof(jit)) == 0)
847 break;
848 } else if (jit.prg == cjit.prg && jit.lit == cjit.lit) {
849 prg_len = jit.prg - jit.start;
850 lit_len = jit.lit - jit.mid;
851 size = prg_len + lit_len;
852 if (size >= BPF_SIZE_MAX)
853 goto out;
854 header = bpf_alloc_binary(size, &jit.start);
855 if (!header)
856 goto out;
857 jit.prg = jit.mid = jit.start + prg_len;
858 jit.lit = jit.end = jit.start + prg_len + lit_len;
859 jit.base_ip += (unsigned long) jit.start;
860 jit.exit_ip += (unsigned long) jit.start;
861 jit.ret0_ip += (unsigned long) jit.start;
862 }
863 cjit = jit;
864 }
865 if (bpf_jit_enable > 1) {
866 bpf_jit_dump(fp->len, jit.end - jit.start, pass, jit.start);
867 if (jit.start)
868 print_fn_code(jit.start, jit.mid - jit.start);
869 }
870 if (jit.start) {
871 set_memory_ro((unsigned long)header, header->pages);
872 fp->bpf_func = (void *) jit.start;
873 }
874 out:
875 kfree(addrs);
876 }
877
878 void bpf_jit_free(struct sk_filter *fp)
879 {
880 unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
881 struct bpf_binary_header *header = (void *)addr;
882
883 if (fp->bpf_func == sk_run_filter)
884 return;
885 set_memory_rw(addr, header->pages);
886 module_free(NULL, header);
887 }
CRIS linux kernel tree