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x86 bpf_jit: fix a bug in emitting the 16-bit immediate operand of AND
[deliverable/linux.git] / arch / x86 / net / bpf_jit_comp.c
CommitLineData
0a14842f
ED		 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++) {
d00a9dd2 154 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
0a14842f
ED		 155 /* no prologue/epilogue for trivial filters (RET something) */
156 proglen = 0;
157 prog = temp;
158
d00a9dd2 159 if (seen_or_pass0) {
0a14842f
ED		 160 EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
161 EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */
162 /* note : must save %rbx in case bpf_error is hit */
d00a9dd2 163 if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF))
0a14842f 164 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
d00a9dd2 165 if (seen_or_pass0 & SEEN_XREG)
0a14842f
ED		 166 CLEAR_X(); /* make sure we dont leek kernel memory */
167
168 /*
169 * If this filter needs to access skb data,
170 * loads r9 and r8 with :
171 * r9 = skb->len - skb->data_len
172 * r8 = skb->data
173 */
d00a9dd2 174 if (seen_or_pass0 & SEEN_DATAREF) {
0a14842f
ED		 175 if (offsetof(struct sk_buff, len) <= 127)
176 /* mov off8(%rdi),%r9d */
177 EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
178 else {
179 /* mov off32(%rdi),%r9d */
180 EMIT3(0x44, 0x8b, 0x8f);
181 EMIT(offsetof(struct sk_buff, len), 4);
182 }
183 if (is_imm8(offsetof(struct sk_buff, data_len)))
184 /* sub off8(%rdi),%r9d */
185 EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
186 else {
187 EMIT3(0x44, 0x2b, 0x8f);
188 EMIT(offsetof(struct sk_buff, data_len), 4);
189 }
190
191 if (is_imm8(offsetof(struct sk_buff, data)))
192 /* mov off8(%rdi),%r8 */
193 EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
194 else {
195 /* mov off32(%rdi),%r8 */
196 EMIT3(0x4c, 0x8b, 0x87);
197 EMIT(offsetof(struct sk_buff, data), 4);
198 }
199 }
200 }
201
202 switch (filter[0].code) {
203 case BPF_S_RET_K:
204 case BPF_S_LD_W_LEN:
205 case BPF_S_ANC_PROTOCOL:
206 case BPF_S_ANC_IFINDEX:
207 case BPF_S_ANC_MARK:
208 case BPF_S_ANC_RXHASH:
209 case BPF_S_ANC_CPU:
210 case BPF_S_ANC_QUEUE:
211 case BPF_S_LD_W_ABS:
212 case BPF_S_LD_H_ABS:
213 case BPF_S_LD_B_ABS:
214 /* first instruction sets A register (or is RET 'constant') */
215 break;
216 default:
217 /* make sure we dont leak kernel information to user */
218 CLEAR_A(); /* A = 0 */
219 }
220
221 for (i = 0; i < flen; i++) {
222 unsigned int K = filter[i].k;
223
224 switch (filter[i].code) {
225 case BPF_S_ALU_ADD_X: /* A += X; */
226 seen |= SEEN_XREG;
227 EMIT2(0x01, 0xd8); /* add %ebx,%eax */
228 break;
229 case BPF_S_ALU_ADD_K: /* A += K; */
230 if (!K)
231 break;
232 if (is_imm8(K))
233 EMIT3(0x83, 0xc0, K); /* add imm8,%eax */
234 else
235 EMIT1_off32(0x05, K); /* add imm32,%eax */
236 break;
237 case BPF_S_ALU_SUB_X: /* A -= X; */
238 seen |= SEEN_XREG;
239 EMIT2(0x29, 0xd8); /* sub %ebx,%eax */
240 break;
241 case BPF_S_ALU_SUB_K: /* A -= K */
242 if (!K)
243 break;
244 if (is_imm8(K))
245 EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
246 else
247 EMIT1_off32(0x2d, K); /* sub imm32,%eax */
248 break;
249 case BPF_S_ALU_MUL_X: /* A *= X; */
250 seen |= SEEN_XREG;
251 EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */
252 break;
253 case BPF_S_ALU_MUL_K: /* A *= K */
254 if (is_imm8(K))
255 EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
256 else {
257 EMIT2(0x69, 0xc0); /* imul imm32,%eax */
258 EMIT(K, 4);
259 }
260 break;
261 case BPF_S_ALU_DIV_X: /* A /= X; */
262 seen |= SEEN_XREG;
263 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
d00a9dd2
ED		 264 if (pc_ret0 > 0) {
265 /* addrs[pc_ret0 - 1] is start address of target
266 * (addrs[i] - 4) is the address following this jmp
267 * ("xor %edx,%edx; div %ebx" being 4 bytes long)
268 */
269 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
270 (addrs[i] - 4));
271 } else {
0a14842f
ED		 272 EMIT_COND_JMP(X86_JNE, 2 + 5);
273 CLEAR_A();
274 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
275 }
276 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
277 break;
278 case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
279 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
280 EMIT(K, 4);
281 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
282 break;
283 case BPF_S_ALU_AND_X:
284 seen |= SEEN_XREG;
285 EMIT2(0x21, 0xd8); /* and %ebx,%eax */
286 break;
287 case BPF_S_ALU_AND_K:
288 if (K >= 0xFFFFFF00) {
289 EMIT2(0x24, K & 0xFF); /* and imm8,%al */
290 } else if (K >= 0xFFFF0000) {
291 EMIT2(0x66, 0x25); /* and imm16,%ax */
1d24fb36 292 EMIT(K, 2);
0a14842f
ED		 293 } else {
294 EMIT1_off32(0x25, K); /* and imm32,%eax */
295 }
296 break;
297 case BPF_S_ALU_OR_X:
298 seen |= SEEN_XREG;
299 EMIT2(0x09, 0xd8); /* or %ebx,%eax */
300 break;
301 case BPF_S_ALU_OR_K:
302 if (is_imm8(K))
303 EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
304 else
305 EMIT1_off32(0x0d, K); /* or imm32,%eax */
306 break;
307 case BPF_S_ALU_LSH_X: /* A <<= X; */
308 seen |= SEEN_XREG;
309 EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */
310 break;
311 case BPF_S_ALU_LSH_K:
312 if (K == 0)
313 break;
314 else if (K == 1)
315 EMIT2(0xd1, 0xe0); /* shl %eax */
316 else
317 EMIT3(0xc1, 0xe0, K);
318 break;
319 case BPF_S_ALU_RSH_X: /* A >>= X; */
320 seen |= SEEN_XREG;
321 EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */
322 break;
323 case BPF_S_ALU_RSH_K: /* A >>= K; */
324 if (K == 0)
325 break;
326 else if (K == 1)
327 EMIT2(0xd1, 0xe8); /* shr %eax */
328 else
329 EMIT3(0xc1, 0xe8, K);
330 break;
331 case BPF_S_ALU_NEG:
332 EMIT2(0xf7, 0xd8); /* neg %eax */
333 break;
334 case BPF_S_RET_K:
335 if (!K) {
336 if (pc_ret0 == -1)
337 pc_ret0 = i;
338 CLEAR_A();
339 } else {
340 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
341 }
342 /* fallinto */
343 case BPF_S_RET_A:
d00a9dd2 344 if (seen_or_pass0) {
0a14842f
ED		 345 if (i != flen - 1) {
346 EMIT_JMP(cleanup_addr - addrs[i]);
347 break;
348 }
d00a9dd2 349 if (seen_or_pass0 & SEEN_XREG)
0a14842f
ED		 350 EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */
351 EMIT1(0xc9); /* leaveq */
352 }
353 EMIT1(0xc3); /* ret */
354 break;
355 case BPF_S_MISC_TAX: /* X = A */
356 seen |= SEEN_XREG;
357 EMIT2(0x89, 0xc3); /* mov %eax,%ebx */
358 break;
359 case BPF_S_MISC_TXA: /* A = X */
360 seen |= SEEN_XREG;
361 EMIT2(0x89, 0xd8); /* mov %ebx,%eax */
362 break;
363 case BPF_S_LD_IMM: /* A = K */
364 if (!K)
365 CLEAR_A();
366 else
367 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
368 break;
369 case BPF_S_LDX_IMM: /* X = K */
370 seen |= SEEN_XREG;
371 if (!K)
372 CLEAR_X();
373 else
374 EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
375 break;
376 case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
377 seen |= SEEN_MEM;
378 EMIT3(0x8b, 0x45, 0xf0 - K*4);
379 break;
380 case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
381 seen |= SEEN_XREG | SEEN_MEM;
382 EMIT3(0x8b, 0x5d, 0xf0 - K*4);
383 break;
384 case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
385 seen |= SEEN_MEM;
386 EMIT3(0x89, 0x45, 0xf0 - K*4);
387 break;
388 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
389 seen |= SEEN_XREG | SEEN_MEM;
390 EMIT3(0x89, 0x5d, 0xf0 - K*4);
391 break;
392 case BPF_S_LD_W_LEN: /* A = skb->len; */
393 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
394 if (is_imm8(offsetof(struct sk_buff, len)))
395 /* mov off8(%rdi),%eax */
396 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
397 else {
398 EMIT2(0x8b, 0x87);
399 EMIT(offsetof(struct sk_buff, len), 4);
400 }
401 break;
402 case BPF_S_LDX_W_LEN: /* X = skb->len; */
403 seen |= SEEN_XREG;
404 if (is_imm8(offsetof(struct sk_buff, len)))
405 /* mov off8(%rdi),%ebx */
406 EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
407 else {
408 EMIT2(0x8b, 0x9f);
409 EMIT(offsetof(struct sk_buff, len), 4);
410 }
411 break;
412 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
413 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
414 if (is_imm8(offsetof(struct sk_buff, protocol))) {
415 /* movzwl off8(%rdi),%eax */
416 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
417 } else {
418 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
419 EMIT(offsetof(struct sk_buff, protocol), 4);
420 }
421 EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */
422 break;
423 case BPF_S_ANC_IFINDEX:
424 if (is_imm8(offsetof(struct sk_buff, dev))) {
425 /* movq off8(%rdi),%rax */
426 EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
427 } else {
428 EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
429 EMIT(offsetof(struct sk_buff, dev), 4);
430 }
431 EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */
432 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
433 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
434 EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */
435 EMIT(offsetof(struct net_device, ifindex), 4);
436 break;
437 case BPF_S_ANC_MARK:
438 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
439 if (is_imm8(offsetof(struct sk_buff, mark))) {
440 /* mov off8(%rdi),%eax */
441 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
442 } else {
443 EMIT2(0x8b, 0x87);
444 EMIT(offsetof(struct sk_buff, mark), 4);
445 }
446 break;
447 case BPF_S_ANC_RXHASH:
448 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
449 if (is_imm8(offsetof(struct sk_buff, rxhash))) {
450 /* mov off8(%rdi),%eax */
451 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
452 } else {
453 EMIT2(0x8b, 0x87);
454 EMIT(offsetof(struct sk_buff, rxhash), 4);
455 }
456 break;
457 case BPF_S_ANC_QUEUE:
458 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
459 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
460 /* movzwl off8(%rdi),%eax */
461 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
462 } else {
463 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
464 EMIT(offsetof(struct sk_buff, queue_mapping), 4);
465 }
466 break;
467 case BPF_S_ANC_CPU:
468#ifdef CONFIG_SMP
469 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
470 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
471#else
472 CLEAR_A();
473#endif
474 break;
475 case BPF_S_LD_W_ABS:
476 func = sk_load_word;
477common_load: seen |= SEEN_DATAREF;
dc72d99d
ED		 478 if ((int)K < 0) {
479 /* Abort the JIT because __load_pointer() is needed. */
0a14842f 480 goto out;
dc72d99d 481 }
0a14842f
ED		 482 t_offset = func - (image + addrs[i]);
483 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
484 EMIT1_off32(0xe8, t_offset); /* call */
485 break;
486 case BPF_S_LD_H_ABS:
487 func = sk_load_half;
488 goto common_load;
489 case BPF_S_LD_B_ABS:
490 func = sk_load_byte;
491 goto common_load;
492 case BPF_S_LDX_B_MSH:
493 if ((int)K < 0) {
dc72d99d
ED		 494 /* Abort the JIT because __load_pointer() is needed. */
495 goto out;
0a14842f
ED		 496 }
497 seen |= SEEN_DATAREF | SEEN_XREG;
498 t_offset = sk_load_byte_msh - (image + addrs[i]);
499 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
500 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
501 break;
502 case BPF_S_LD_W_IND:
503 func = sk_load_word_ind;
504common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG;
505 t_offset = func - (image + addrs[i]);
506 EMIT1_off32(0xbe, K); /* mov imm32,%esi */
507 EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */
508 break;
509 case BPF_S_LD_H_IND:
510 func = sk_load_half_ind;
511 goto common_load_ind;
512 case BPF_S_LD_B_IND:
513 func = sk_load_byte_ind;
514 goto common_load_ind;
515 case BPF_S_JMP_JA:
516 t_offset = addrs[i + K] - addrs[i];
517 EMIT_JMP(t_offset);
518 break;
519 COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
520 COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
521 COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
522 COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
523 COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
524 COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
525 COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
526 COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
527
528cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
529 t_offset = addrs[i + filter[i].jt] - addrs[i];
530
531 /* same targets, can avoid doing the test :) */
532 if (filter[i].jt == filter[i].jf) {
533 EMIT_JMP(t_offset);
534 break;
535 }
536
537 switch (filter[i].code) {
538 case BPF_S_JMP_JGT_X:
539 case BPF_S_JMP_JGE_X:
540 case BPF_S_JMP_JEQ_X:
541 seen |= SEEN_XREG;
542 EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
543 break;
544 case BPF_S_JMP_JSET_X:
545 seen |= SEEN_XREG;
546 EMIT2(0x85, 0xd8); /* test %ebx,%eax */
547 break;
548 case BPF_S_JMP_JEQ_K:
549 if (K == 0) {
550 EMIT2(0x85, 0xc0); /* test %eax,%eax */
551 break;
552 }
553 case BPF_S_JMP_JGT_K:
554 case BPF_S_JMP_JGE_K:
555 if (K <= 127)
556 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
557 else
558 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
559 break;
560 case BPF_S_JMP_JSET_K:
561 if (K <= 0xFF)
562 EMIT2(0xa8, K); /* test imm8,%al */
563 else if (!(K & 0xFFFF00FF))
564 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
565 else if (K <= 0xFFFF) {
566 EMIT2(0x66, 0xa9); /* test imm16,%ax */
567 EMIT(K, 2);
568 } else {
569 EMIT1_off32(0xa9, K); /* test imm32,%eax */
570 }
571 break;
572 }
573 if (filter[i].jt != 0) {
a03ffcf8
MK		 574 if (filter[i].jf && f_offset)
575 t_offset += is_near(f_offset) ? 2 : 5;
0a14842f
ED		 576 EMIT_COND_JMP(t_op, t_offset);
577 if (filter[i].jf)
578 EMIT_JMP(f_offset);
579 break;
580 }
581 EMIT_COND_JMP(f_op, f_offset);
582 break;
583 default:
584 /* hmm, too complex filter, give up with jit compiler */
585 goto out;
586 }
587 ilen = prog - temp;
588 if (image) {
589 if (unlikely(proglen + ilen > oldproglen)) {
590 pr_err("bpb_jit_compile fatal error\n");
591 kfree(addrs);
592 module_free(NULL, image);
593 return;
594 }
595 memcpy(image + proglen, temp, ilen);
596 }
597 proglen += ilen;
598 addrs[i] = proglen;
599 prog = temp;
600 }
601 /* last bpf instruction is always a RET :
602 * use it to give the cleanup instruction(s) addr
603 */
604 cleanup_addr = proglen - 1; /* ret */
d00a9dd2 605 if (seen_or_pass0)
0a14842f 606 cleanup_addr -= 1; /* leaveq */
d00a9dd2 607 if (seen_or_pass0 & SEEN_XREG)
0a14842f
ED		 608 cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
609
610 if (image) {
d00a9dd2
ED		 611 if (proglen != oldproglen)
612 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
0a14842f
ED		 613 break;
614 }
615 if (proglen == oldproglen) {
616 image = module_alloc(max_t(unsigned int,
617 proglen,
618 sizeof(struct work_struct)));
619 if (!image)
620 goto out;
621 }
622 oldproglen = proglen;
623 }
624 if (bpf_jit_enable > 1)
625 pr_err("flen=%d proglen=%u pass=%d image=%p\n",
626 flen, proglen, pass, image);
627
628 if (image) {
629 if (bpf_jit_enable > 1)
630 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
631 16, 1, image, proglen, false);
632
633 bpf_flush_icache(image, image + proglen);
634
635 fp->bpf_func = (void *)image;
636 }
637out:
638 kfree(addrs);
639 return;
640}
641
642static void jit_free_defer(struct work_struct *arg)
643{
644 module_free(NULL, arg);
645}
646
647/* run from softirq, we must use a work_struct to call
648 * module_free() from process context
649 */
650void bpf_jit_free(struct sk_filter *fp)
651{
652 if (fp->bpf_func != sk_run_filter) {
653 struct work_struct *work = (struct work_struct *)fp->bpf_func;
654
655 INIT_WORK(work, jit_free_defer);
656 schedule_work(work);
657 }
658}
Linux kernel - Deliverables
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