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