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bpf: Make the bpf_prog_array_map more generic
[linux-2.6/btrfs-unstable.git] / arch / x86 / net / bpf_jit_comp.c
blob70efcd0940f9f34b8649872b5b1ac44853a8e5f0
1 /* bpf_jit_comp.c : BPF JIT compiler
2 *
3 * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com)
4 * Internal BPF Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; version 2
9 * of the License.
10 */
11 #include <linux/netdevice.h>
12 #include <linux/filter.h>
13 #include <linux/if_vlan.h>
14 #include <asm/cacheflush.h>
15 #include <linux/bpf.h>
16
17 int bpf_jit_enable __read_mostly;
18
19 /*
20 * assembly code in arch/x86/net/bpf_jit.S
21 */
22 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
23 extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[];
24 extern u8 sk_load_byte_positive_offset[];
25 extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[];
26 extern u8 sk_load_byte_negative_offset[];
27
28 static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
29 {
30 if (len == 1)
31 *ptr = bytes;
32 else if (len == 2)
33 *(u16 *)ptr = bytes;
34 else {
35 *(u32 *)ptr = bytes;
36 barrier();
37 }
38 return ptr + len;
39 }
40
41 #define EMIT(bytes, len) \
42 do { prog = emit_code(prog, bytes, len); cnt += len; } while (0)
43
44 #define EMIT1(b1) EMIT(b1, 1)
45 #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
46 #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
47 #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
48 #define EMIT1_off32(b1, off) \
49 do {EMIT1(b1); EMIT(off, 4); } while (0)
50 #define EMIT2_off32(b1, b2, off) \
51 do {EMIT2(b1, b2); EMIT(off, 4); } while (0)
52 #define EMIT3_off32(b1, b2, b3, off) \
53 do {EMIT3(b1, b2, b3); EMIT(off, 4); } while (0)
54 #define EMIT4_off32(b1, b2, b3, b4, off) \
55 do {EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0)
56
57 static bool is_imm8(int value)
58 {
59 return value <= 127 && value >= -128;
60 }
61
62 static bool is_simm32(s64 value)
63 {
64 return value == (s64) (s32) value;
65 }
66
67 /* mov dst, src */
68 #define EMIT_mov(DST, SRC) \
69 do {if (DST != SRC) \
70 EMIT3(add_2mod(0x48, DST, SRC), 0x89, add_2reg(0xC0, DST, SRC)); \
71 } while (0)
72
73 static int bpf_size_to_x86_bytes(int bpf_size)
74 {
75 if (bpf_size == BPF_W)
76 return 4;
77 else if (bpf_size == BPF_H)
78 return 2;
79 else if (bpf_size == BPF_B)
80 return 1;
81 else if (bpf_size == BPF_DW)
82 return 4; /* imm32 */
83 else
84 return 0;
85 }
86
87 /* list of x86 cond jumps opcodes (. + s8)
88 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
89 */
90 #define X86_JB 0x72
91 #define X86_JAE 0x73
92 #define X86_JE 0x74
93 #define X86_JNE 0x75
94 #define X86_JBE 0x76
95 #define X86_JA 0x77
96 #define X86_JGE 0x7D
97 #define X86_JG 0x7F
98
99 static void bpf_flush_icache(void *start, void *end)
100 {
101 mm_segment_t old_fs = get_fs();
102
103 set_fs(KERNEL_DS);
104 smp_wmb();
105 flush_icache_range((unsigned long)start, (unsigned long)end);
106 set_fs(old_fs);
107 }
108
109 #define CHOOSE_LOAD_FUNC(K, func) \
110 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
111
112 /* pick a register outside of BPF range for JIT internal work */
113 #define AUX_REG (MAX_BPF_REG + 1)
114
115 /* the following table maps BPF registers to x64 registers.
116 * x64 register r12 is unused, since if used as base address register
117 * in load/store instructions, it always needs an extra byte of encoding
118 */
119 static const int reg2hex[] = {
120 [BPF_REG_0] = 0, /* rax */
121 [BPF_REG_1] = 7, /* rdi */
122 [BPF_REG_2] = 6, /* rsi */
123 [BPF_REG_3] = 2, /* rdx */
124 [BPF_REG_4] = 1, /* rcx */
125 [BPF_REG_5] = 0, /* r8 */
126 [BPF_REG_6] = 3, /* rbx callee saved */
127 [BPF_REG_7] = 5, /* r13 callee saved */
128 [BPF_REG_8] = 6, /* r14 callee saved */
129 [BPF_REG_9] = 7, /* r15 callee saved */
130 [BPF_REG_FP] = 5, /* rbp readonly */
131 [AUX_REG] = 3, /* r11 temp register */
132 };
133
134 /* is_ereg() == true if BPF register 'reg' maps to x64 r8..r15
135 * which need extra byte of encoding.
136 * rax,rcx,...,rbp have simpler encoding
137 */
138 static bool is_ereg(u32 reg)
139 {
140 return (1 << reg) & (BIT(BPF_REG_5) |
141 BIT(AUX_REG) |
142 BIT(BPF_REG_7) |
143 BIT(BPF_REG_8) |
144 BIT(BPF_REG_9));
145 }
146
147 /* add modifiers if 'reg' maps to x64 registers r8..r15 */
148 static u8 add_1mod(u8 byte, u32 reg)
149 {
150 if (is_ereg(reg))
151 byte |= 1;
152 return byte;
153 }
154
155 static u8 add_2mod(u8 byte, u32 r1, u32 r2)
156 {
157 if (is_ereg(r1))
158 byte |= 1;
159 if (is_ereg(r2))
160 byte |= 4;
161 return byte;
162 }
163
164 /* encode 'dst_reg' register into x64 opcode 'byte' */
165 static u8 add_1reg(u8 byte, u32 dst_reg)
166 {
167 return byte + reg2hex[dst_reg];
168 }
169
170 /* encode 'dst_reg' and 'src_reg' registers into x64 opcode 'byte' */
171 static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg)
172 {
173 return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3);
174 }
175
176 static void jit_fill_hole(void *area, unsigned int size)
177 {
178 /* fill whole space with int3 instructions */
179 memset(area, 0xcc, size);
180 }
181
182 struct jit_context {
183 int cleanup_addr; /* epilogue code offset */
184 bool seen_ld_abs;
185 };
186
187 /* maximum number of bytes emitted while JITing one eBPF insn */
188 #define BPF_MAX_INSN_SIZE 128
189 #define BPF_INSN_SAFETY 64
190
191 #define STACKSIZE \
192 (MAX_BPF_STACK + \
193 32 /* space for rbx, r13, r14, r15 */ + \
194 8 /* space for skb_copy_bits() buffer */)
195
196 #define PROLOGUE_SIZE 51
197
198 /* emit x64 prologue code for BPF program and check it's size.
199 * bpf_tail_call helper will skip it while jumping into another program
200 */
201 static void emit_prologue(u8 **pprog)
202 {
203 u8 *prog = *pprog;
204 int cnt = 0;
205
206 EMIT1(0x55); /* push rbp */
207 EMIT3(0x48, 0x89, 0xE5); /* mov rbp,rsp */
208
209 /* sub rsp, STACKSIZE */
210 EMIT3_off32(0x48, 0x81, 0xEC, STACKSIZE);
211
212 /* all classic BPF filters use R6(rbx) save it */
213
214 /* mov qword ptr [rbp-X],rbx */
215 EMIT3_off32(0x48, 0x89, 0x9D, -STACKSIZE);
216
217 /* bpf_convert_filter() maps classic BPF register X to R7 and uses R8
218 * as temporary, so all tcpdump filters need to spill/fill R7(r13) and
219 * R8(r14). R9(r15) spill could be made conditional, but there is only
220 * one 'bpf_error' return path out of helper functions inside bpf_jit.S
221 * The overhead of extra spill is negligible for any filter other
222 * than synthetic ones. Therefore not worth adding complexity.
223 */
224
225 /* mov qword ptr [rbp-X],r13 */
226 EMIT3_off32(0x4C, 0x89, 0xAD, -STACKSIZE + 8);
227 /* mov qword ptr [rbp-X],r14 */
228 EMIT3_off32(0x4C, 0x89, 0xB5, -STACKSIZE + 16);
229 /* mov qword ptr [rbp-X],r15 */
230 EMIT3_off32(0x4C, 0x89, 0xBD, -STACKSIZE + 24);
231
232 /* clear A and X registers */
233 EMIT2(0x31, 0xc0); /* xor eax, eax */
234 EMIT3(0x4D, 0x31, 0xED); /* xor r13, r13 */
235
236 /* clear tail_cnt: mov qword ptr [rbp-X], rax */
237 EMIT3_off32(0x48, 0x89, 0x85, -STACKSIZE + 32);
238
239 BUILD_BUG_ON(cnt != PROLOGUE_SIZE);
240 *pprog = prog;
241 }
242
243 /* generate the following code:
244 * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
245 * if (index >= array->map.max_entries)
246 * goto out;
247 * if (++tail_call_cnt > MAX_TAIL_CALL_CNT)
248 * goto out;
249 * prog = array->ptrs[index];
250 * if (prog == NULL)
251 * goto out;
252 * goto *(prog->bpf_func + prologue_size);
253 * out:
254 */
255 static void emit_bpf_tail_call(u8 **pprog)
256 {
257 u8 *prog = *pprog;
258 int label1, label2, label3;
259 int cnt = 0;
260
261 /* rdi - pointer to ctx
262 * rsi - pointer to bpf_array
263 * rdx - index in bpf_array
264 */
265
266 /* if (index >= array->map.max_entries)
267 * goto out;
268 */
269 EMIT4(0x48, 0x8B, 0x46, /* mov rax, qword ptr [rsi + 16] */
270 offsetof(struct bpf_array, map.max_entries));
271 EMIT3(0x48, 0x39, 0xD0); /* cmp rax, rdx */
272 #define OFFSET1 47 /* number of bytes to jump */
273 EMIT2(X86_JBE, OFFSET1); /* jbe out */
274 label1 = cnt;
275
276 /* if (tail_call_cnt > MAX_TAIL_CALL_CNT)
277 * goto out;
278 */
279 EMIT2_off32(0x8B, 0x85, -STACKSIZE + 36); /* mov eax, dword ptr [rbp - 516] */
280 EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */
281 #define OFFSET2 36
282 EMIT2(X86_JA, OFFSET2); /* ja out */
283 label2 = cnt;
284 EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */
285 EMIT2_off32(0x89, 0x85, -STACKSIZE + 36); /* mov dword ptr [rbp - 516], eax */
286
287 /* prog = array->ptrs[index]; */
288 EMIT4_off32(0x48, 0x8D, 0x84, 0xD6, /* lea rax, [rsi + rdx * 8 + offsetof(...)] */
289 offsetof(struct bpf_array, ptrs));
290 EMIT3(0x48, 0x8B, 0x00); /* mov rax, qword ptr [rax] */
291
292 /* if (prog == NULL)
293 * goto out;
294 */
295 EMIT4(0x48, 0x83, 0xF8, 0x00); /* cmp rax, 0 */
296 #define OFFSET3 10
297 EMIT2(X86_JE, OFFSET3); /* je out */
298 label3 = cnt;
299
300 /* goto *(prog->bpf_func + prologue_size); */
301 EMIT4(0x48, 0x8B, 0x40, /* mov rax, qword ptr [rax + 32] */
302 offsetof(struct bpf_prog, bpf_func));
303 EMIT4(0x48, 0x83, 0xC0, PROLOGUE_SIZE); /* add rax, prologue_size */
304
305 /* now we're ready to jump into next BPF program
306 * rdi == ctx (1st arg)
307 * rax == prog->bpf_func + prologue_size
308 */
309 EMIT2(0xFF, 0xE0); /* jmp rax */
310
311 /* out: */
312 BUILD_BUG_ON(cnt - label1 != OFFSET1);
313 BUILD_BUG_ON(cnt - label2 != OFFSET2);
314 BUILD_BUG_ON(cnt - label3 != OFFSET3);
315 *pprog = prog;
316 }
317
318
319 static void emit_load_skb_data_hlen(u8 **pprog)
320 {
321 u8 *prog = *pprog;
322 int cnt = 0;
323
324 /* r9d = skb->len - skb->data_len (headlen)
325 * r10 = skb->data
326 */
327 /* mov %r9d, off32(%rdi) */
328 EMIT3_off32(0x44, 0x8b, 0x8f, offsetof(struct sk_buff, len));
329
330 /* sub %r9d, off32(%rdi) */
331 EMIT3_off32(0x44, 0x2b, 0x8f, offsetof(struct sk_buff, data_len));
332
333 /* mov %r10, off32(%rdi) */
334 EMIT3_off32(0x4c, 0x8b, 0x97, offsetof(struct sk_buff, data));
335 *pprog = prog;
336 }
337
338 static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
339 int oldproglen, struct jit_context *ctx)
340 {
341 struct bpf_insn *insn = bpf_prog->insnsi;
342 int insn_cnt = bpf_prog->len;
343 bool seen_ld_abs = ctx->seen_ld_abs | (oldproglen == 0);
344 bool seen_exit = false;
345 u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY];
346 int i, cnt = 0;
347 int proglen = 0;
348 u8 *prog = temp;
349
350 emit_prologue(&prog);
351
352 if (seen_ld_abs)
353 emit_load_skb_data_hlen(&prog);
354
355 for (i = 0; i < insn_cnt; i++, insn++) {
356 const s32 imm32 = insn->imm;
357 u32 dst_reg = insn->dst_reg;
358 u32 src_reg = insn->src_reg;
359 u8 b1 = 0, b2 = 0, b3 = 0;
360 s64 jmp_offset;
361 u8 jmp_cond;
362 bool reload_skb_data;
363 int ilen;
364 u8 *func;
365
366 switch (insn->code) {
367 /* ALU */
368 case BPF_ALU | BPF_ADD | BPF_X:
369 case BPF_ALU | BPF_SUB | BPF_X:
370 case BPF_ALU | BPF_AND | BPF_X:
371 case BPF_ALU | BPF_OR | BPF_X:
372 case BPF_ALU | BPF_XOR | BPF_X:
373 case BPF_ALU64 | BPF_ADD | BPF_X:
374 case BPF_ALU64 | BPF_SUB | BPF_X:
375 case BPF_ALU64 | BPF_AND | BPF_X:
376 case BPF_ALU64 | BPF_OR | BPF_X:
377 case BPF_ALU64 | BPF_XOR | BPF_X:
378 switch (BPF_OP(insn->code)) {
379 case BPF_ADD: b2 = 0x01; break;
380 case BPF_SUB: b2 = 0x29; break;
381 case BPF_AND: b2 = 0x21; break;
382 case BPF_OR: b2 = 0x09; break;
383 case BPF_XOR: b2 = 0x31; break;
384 }
385 if (BPF_CLASS(insn->code) == BPF_ALU64)
386 EMIT1(add_2mod(0x48, dst_reg, src_reg));
387 else if (is_ereg(dst_reg) || is_ereg(src_reg))
388 EMIT1(add_2mod(0x40, dst_reg, src_reg));
389 EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg));
390 break;
391
392 /* mov dst, src */
393 case BPF_ALU64 | BPF_MOV | BPF_X:
394 EMIT_mov(dst_reg, src_reg);
395 break;
396
397 /* mov32 dst, src */
398 case BPF_ALU | BPF_MOV | BPF_X:
399 if (is_ereg(dst_reg) || is_ereg(src_reg))
400 EMIT1(add_2mod(0x40, dst_reg, src_reg));
401 EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg));
402 break;
403
404 /* neg dst */
405 case BPF_ALU | BPF_NEG:
406 case BPF_ALU64 | BPF_NEG:
407 if (BPF_CLASS(insn->code) == BPF_ALU64)
408 EMIT1(add_1mod(0x48, dst_reg));
409 else if (is_ereg(dst_reg))
410 EMIT1(add_1mod(0x40, dst_reg));
411 EMIT2(0xF7, add_1reg(0xD8, dst_reg));
412 break;
413
414 case BPF_ALU | BPF_ADD | BPF_K:
415 case BPF_ALU | BPF_SUB | BPF_K:
416 case BPF_ALU | BPF_AND | BPF_K:
417 case BPF_ALU | BPF_OR | BPF_K:
418 case BPF_ALU | BPF_XOR | BPF_K:
419 case BPF_ALU64 | BPF_ADD | BPF_K:
420 case BPF_ALU64 | BPF_SUB | BPF_K:
421 case BPF_ALU64 | BPF_AND | BPF_K:
422 case BPF_ALU64 | BPF_OR | BPF_K:
423 case BPF_ALU64 | BPF_XOR | BPF_K:
424 if (BPF_CLASS(insn->code) == BPF_ALU64)
425 EMIT1(add_1mod(0x48, dst_reg));
426 else if (is_ereg(dst_reg))
427 EMIT1(add_1mod(0x40, dst_reg));
428
429 switch (BPF_OP(insn->code)) {
430 case BPF_ADD: b3 = 0xC0; break;
431 case BPF_SUB: b3 = 0xE8; break;
432 case BPF_AND: b3 = 0xE0; break;
433 case BPF_OR: b3 = 0xC8; break;
434 case BPF_XOR: b3 = 0xF0; break;
435 }
436
437 if (is_imm8(imm32))
438 EMIT3(0x83, add_1reg(b3, dst_reg), imm32);
439 else
440 EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32);
441 break;
442
443 case BPF_ALU64 | BPF_MOV | BPF_K:
444 /* optimization: if imm32 is positive,
445 * use 'mov eax, imm32' (which zero-extends imm32)
446 * to save 2 bytes
447 */
448 if (imm32 < 0) {
449 /* 'mov rax, imm32' sign extends imm32 */
450 b1 = add_1mod(0x48, dst_reg);
451 b2 = 0xC7;
452 b3 = 0xC0;
453 EMIT3_off32(b1, b2, add_1reg(b3, dst_reg), imm32);
454 break;
455 }
456
457 case BPF_ALU | BPF_MOV | BPF_K:
458 /* mov %eax, imm32 */
459 if (is_ereg(dst_reg))
460 EMIT1(add_1mod(0x40, dst_reg));
461 EMIT1_off32(add_1reg(0xB8, dst_reg), imm32);
462 break;
463
464 case BPF_LD | BPF_IMM | BPF_DW:
465 if (insn[1].code != 0 || insn[1].src_reg != 0 ||
466 insn[1].dst_reg != 0 || insn[1].off != 0) {
467 /* verifier must catch invalid insns */
468 pr_err("invalid BPF_LD_IMM64 insn\n");
469 return -EINVAL;
470 }
471
472 /* movabsq %rax, imm64 */
473 EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg));
474 EMIT(insn[0].imm, 4);
475 EMIT(insn[1].imm, 4);
476
477 insn++;
478 i++;
479 break;
480
481 /* dst %= src, dst /= src, dst %= imm32, dst /= imm32 */
482 case BPF_ALU | BPF_MOD | BPF_X:
483 case BPF_ALU | BPF_DIV | BPF_X:
484 case BPF_ALU | BPF_MOD | BPF_K:
485 case BPF_ALU | BPF_DIV | BPF_K:
486 case BPF_ALU64 | BPF_MOD | BPF_X:
487 case BPF_ALU64 | BPF_DIV | BPF_X:
488 case BPF_ALU64 | BPF_MOD | BPF_K:
489 case BPF_ALU64 | BPF_DIV | BPF_K:
490 EMIT1(0x50); /* push rax */
491 EMIT1(0x52); /* push rdx */
492
493 if (BPF_SRC(insn->code) == BPF_X)
494 /* mov r11, src_reg */
495 EMIT_mov(AUX_REG, src_reg);
496 else
497 /* mov r11, imm32 */
498 EMIT3_off32(0x49, 0xC7, 0xC3, imm32);
499
500 /* mov rax, dst_reg */
501 EMIT_mov(BPF_REG_0, dst_reg);
502
503 /* xor edx, edx
504 * equivalent to 'xor rdx, rdx', but one byte less
505 */
506 EMIT2(0x31, 0xd2);
507
508 if (BPF_SRC(insn->code) == BPF_X) {
509 /* if (src_reg == 0) return 0 */
510
511 /* cmp r11, 0 */
512 EMIT4(0x49, 0x83, 0xFB, 0x00);
513
514 /* jne .+9 (skip over pop, pop, xor and jmp) */
515 EMIT2(X86_JNE, 1 + 1 + 2 + 5);
516 EMIT1(0x5A); /* pop rdx */
517 EMIT1(0x58); /* pop rax */
518 EMIT2(0x31, 0xc0); /* xor eax, eax */
519
520 /* jmp cleanup_addr
521 * addrs[i] - 11, because there are 11 bytes
522 * after this insn: div, mov, pop, pop, mov
523 */
524 jmp_offset = ctx->cleanup_addr - (addrs[i] - 11);
525 EMIT1_off32(0xE9, jmp_offset);
526 }
527
528 if (BPF_CLASS(insn->code) == BPF_ALU64)
529 /* div r11 */
530 EMIT3(0x49, 0xF7, 0xF3);
531 else
532 /* div r11d */
533 EMIT3(0x41, 0xF7, 0xF3);
534
535 if (BPF_OP(insn->code) == BPF_MOD)
536 /* mov r11, rdx */
537 EMIT3(0x49, 0x89, 0xD3);
538 else
539 /* mov r11, rax */
540 EMIT3(0x49, 0x89, 0xC3);
541
542 EMIT1(0x5A); /* pop rdx */
543 EMIT1(0x58); /* pop rax */
544
545 /* mov dst_reg, r11 */
546 EMIT_mov(dst_reg, AUX_REG);
547 break;
548
549 case BPF_ALU | BPF_MUL | BPF_K:
550 case BPF_ALU | BPF_MUL | BPF_X:
551 case BPF_ALU64 | BPF_MUL | BPF_K:
552 case BPF_ALU64 | BPF_MUL | BPF_X:
553 EMIT1(0x50); /* push rax */
554 EMIT1(0x52); /* push rdx */
555
556 /* mov r11, dst_reg */
557 EMIT_mov(AUX_REG, dst_reg);
558
559 if (BPF_SRC(insn->code) == BPF_X)
560 /* mov rax, src_reg */
561 EMIT_mov(BPF_REG_0, src_reg);
562 else
563 /* mov rax, imm32 */
564 EMIT3_off32(0x48, 0xC7, 0xC0, imm32);
565
566 if (BPF_CLASS(insn->code) == BPF_ALU64)
567 EMIT1(add_1mod(0x48, AUX_REG));
568 else if (is_ereg(AUX_REG))
569 EMIT1(add_1mod(0x40, AUX_REG));
570 /* mul(q) r11 */
571 EMIT2(0xF7, add_1reg(0xE0, AUX_REG));
572
573 /* mov r11, rax */
574 EMIT_mov(AUX_REG, BPF_REG_0);
575
576 EMIT1(0x5A); /* pop rdx */
577 EMIT1(0x58); /* pop rax */
578
579 /* mov dst_reg, r11 */
580 EMIT_mov(dst_reg, AUX_REG);
581 break;
582
583 /* shifts */
584 case BPF_ALU | BPF_LSH | BPF_K:
585 case BPF_ALU | BPF_RSH | BPF_K:
586 case BPF_ALU | BPF_ARSH | BPF_K:
587 case BPF_ALU64 | BPF_LSH | BPF_K:
588 case BPF_ALU64 | BPF_RSH | BPF_K:
589 case BPF_ALU64 | BPF_ARSH | BPF_K:
590 if (BPF_CLASS(insn->code) == BPF_ALU64)
591 EMIT1(add_1mod(0x48, dst_reg));
592 else if (is_ereg(dst_reg))
593 EMIT1(add_1mod(0x40, dst_reg));
594
595 switch (BPF_OP(insn->code)) {
596 case BPF_LSH: b3 = 0xE0; break;
597 case BPF_RSH: b3 = 0xE8; break;
598 case BPF_ARSH: b3 = 0xF8; break;
599 }
600 EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
601 break;
602
603 case BPF_ALU | BPF_LSH | BPF_X:
604 case BPF_ALU | BPF_RSH | BPF_X:
605 case BPF_ALU | BPF_ARSH | BPF_X:
606 case BPF_ALU64 | BPF_LSH | BPF_X:
607 case BPF_ALU64 | BPF_RSH | BPF_X:
608 case BPF_ALU64 | BPF_ARSH | BPF_X:
609
610 /* check for bad case when dst_reg == rcx */
611 if (dst_reg == BPF_REG_4) {
612 /* mov r11, dst_reg */
613 EMIT_mov(AUX_REG, dst_reg);
614 dst_reg = AUX_REG;
615 }
616
617 if (src_reg != BPF_REG_4) { /* common case */
618 EMIT1(0x51); /* push rcx */
619
620 /* mov rcx, src_reg */
621 EMIT_mov(BPF_REG_4, src_reg);
622 }
623
624 /* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */
625 if (BPF_CLASS(insn->code) == BPF_ALU64)
626 EMIT1(add_1mod(0x48, dst_reg));
627 else if (is_ereg(dst_reg))
628 EMIT1(add_1mod(0x40, dst_reg));
629
630 switch (BPF_OP(insn->code)) {
631 case BPF_LSH: b3 = 0xE0; break;
632 case BPF_RSH: b3 = 0xE8; break;
633 case BPF_ARSH: b3 = 0xF8; break;
634 }
635 EMIT2(0xD3, add_1reg(b3, dst_reg));
636
637 if (src_reg != BPF_REG_4)
638 EMIT1(0x59); /* pop rcx */
639
640 if (insn->dst_reg == BPF_REG_4)
641 /* mov dst_reg, r11 */
642 EMIT_mov(insn->dst_reg, AUX_REG);
643 break;
644
645 case BPF_ALU | BPF_END | BPF_FROM_BE:
646 switch (imm32) {
647 case 16:
648 /* emit 'ror %ax, 8' to swap lower 2 bytes */
649 EMIT1(0x66);
650 if (is_ereg(dst_reg))
651 EMIT1(0x41);
652 EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8);
653
654 /* emit 'movzwl eax, ax' */
655 if (is_ereg(dst_reg))
656 EMIT3(0x45, 0x0F, 0xB7);
657 else
658 EMIT2(0x0F, 0xB7);
659 EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
660 break;
661 case 32:
662 /* emit 'bswap eax' to swap lower 4 bytes */
663 if (is_ereg(dst_reg))
664 EMIT2(0x41, 0x0F);
665 else
666 EMIT1(0x0F);
667 EMIT1(add_1reg(0xC8, dst_reg));
668 break;
669 case 64:
670 /* emit 'bswap rax' to swap 8 bytes */
671 EMIT3(add_1mod(0x48, dst_reg), 0x0F,
672 add_1reg(0xC8, dst_reg));
673 break;
674 }
675 break;
676
677 case BPF_ALU | BPF_END | BPF_FROM_LE:
678 switch (imm32) {
679 case 16:
680 /* emit 'movzwl eax, ax' to zero extend 16-bit
681 * into 64 bit
682 */
683 if (is_ereg(dst_reg))
684 EMIT3(0x45, 0x0F, 0xB7);
685 else
686 EMIT2(0x0F, 0xB7);
687 EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
688 break;
689 case 32:
690 /* emit 'mov eax, eax' to clear upper 32-bits */
691 if (is_ereg(dst_reg))
692 EMIT1(0x45);
693 EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg));
694 break;
695 case 64:
696 /* nop */
697 break;
698 }
699 break;
700
701 /* ST: *(u8*)(dst_reg + off) = imm */
702 case BPF_ST | BPF_MEM | BPF_B:
703 if (is_ereg(dst_reg))
704 EMIT2(0x41, 0xC6);
705 else
706 EMIT1(0xC6);
707 goto st;
708 case BPF_ST | BPF_MEM | BPF_H:
709 if (is_ereg(dst_reg))
710 EMIT3(0x66, 0x41, 0xC7);
711 else
712 EMIT2(0x66, 0xC7);
713 goto st;
714 case BPF_ST | BPF_MEM | BPF_W:
715 if (is_ereg(dst_reg))
716 EMIT2(0x41, 0xC7);
717 else
718 EMIT1(0xC7);
719 goto st;
720 case BPF_ST | BPF_MEM | BPF_DW:
721 EMIT2(add_1mod(0x48, dst_reg), 0xC7);
722
723 st: if (is_imm8(insn->off))
724 EMIT2(add_1reg(0x40, dst_reg), insn->off);
725 else
726 EMIT1_off32(add_1reg(0x80, dst_reg), insn->off);
727
728 EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(insn->code)));
729 break;
730
731 /* STX: *(u8*)(dst_reg + off) = src_reg */
732 case BPF_STX | BPF_MEM | BPF_B:
733 /* emit 'mov byte ptr [rax + off], al' */
734 if (is_ereg(dst_reg) || is_ereg(src_reg) ||
735 /* have to add extra byte for x86 SIL, DIL regs */
736 src_reg == BPF_REG_1 || src_reg == BPF_REG_2)
737 EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88);
738 else
739 EMIT1(0x88);
740 goto stx;
741 case BPF_STX | BPF_MEM | BPF_H:
742 if (is_ereg(dst_reg) || is_ereg(src_reg))
743 EMIT3(0x66, add_2mod(0x40, dst_reg, src_reg), 0x89);
744 else
745 EMIT2(0x66, 0x89);
746 goto stx;
747 case BPF_STX | BPF_MEM | BPF_W:
748 if (is_ereg(dst_reg) || is_ereg(src_reg))
749 EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89);
750 else
751 EMIT1(0x89);
752 goto stx;
753 case BPF_STX | BPF_MEM | BPF_DW:
754 EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89);
755 stx: if (is_imm8(insn->off))
756 EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off);
757 else
758 EMIT1_off32(add_2reg(0x80, dst_reg, src_reg),
759 insn->off);
760 break;
761
762 /* LDX: dst_reg = *(u8*)(src_reg + off) */
763 case BPF_LDX | BPF_MEM | BPF_B:
764 /* emit 'movzx rax, byte ptr [rax + off]' */
765 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6);
766 goto ldx;
767 case BPF_LDX | BPF_MEM | BPF_H:
768 /* emit 'movzx rax, word ptr [rax + off]' */
769 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7);
770 goto ldx;
771 case BPF_LDX | BPF_MEM | BPF_W:
772 /* emit 'mov eax, dword ptr [rax+0x14]' */
773 if (is_ereg(dst_reg) || is_ereg(src_reg))
774 EMIT2(add_2mod(0x40, src_reg, dst_reg), 0x8B);
775 else
776 EMIT1(0x8B);
777 goto ldx;
778 case BPF_LDX | BPF_MEM | BPF_DW:
779 /* emit 'mov rax, qword ptr [rax+0x14]' */
780 EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B);
781 ldx: /* if insn->off == 0 we can save one extra byte, but
782 * special case of x86 r13 which always needs an offset
783 * is not worth the hassle
784 */
785 if (is_imm8(insn->off))
786 EMIT2(add_2reg(0x40, src_reg, dst_reg), insn->off);
787 else
788 EMIT1_off32(add_2reg(0x80, src_reg, dst_reg),
789 insn->off);
790 break;
791
792 /* STX XADD: lock *(u32*)(dst_reg + off) += src_reg */
793 case BPF_STX | BPF_XADD | BPF_W:
794 /* emit 'lock add dword ptr [rax + off], eax' */
795 if (is_ereg(dst_reg) || is_ereg(src_reg))
796 EMIT3(0xF0, add_2mod(0x40, dst_reg, src_reg), 0x01);
797 else
798 EMIT2(0xF0, 0x01);
799 goto xadd;
800 case BPF_STX | BPF_XADD | BPF_DW:
801 EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01);
802 xadd: if (is_imm8(insn->off))
803 EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off);
804 else
805 EMIT1_off32(add_2reg(0x80, dst_reg, src_reg),
806 insn->off);
807 break;
808
809 /* call */
810 case BPF_JMP | BPF_CALL:
811 func = (u8 *) __bpf_call_base + imm32;
812 jmp_offset = func - (image + addrs[i]);
813 if (seen_ld_abs) {
814 reload_skb_data = bpf_helper_changes_skb_data(func);
815 if (reload_skb_data) {
816 EMIT1(0x57); /* push %rdi */
817 jmp_offset += 22; /* pop, mov, sub, mov */
818 } else {
819 EMIT2(0x41, 0x52); /* push %r10 */
820 EMIT2(0x41, 0x51); /* push %r9 */
821 /* need to adjust jmp offset, since
822 * pop %r9, pop %r10 take 4 bytes after call insn
823 */
824 jmp_offset += 4;
825 }
826 }
827 if (!imm32 || !is_simm32(jmp_offset)) {
828 pr_err("unsupported bpf func %d addr %p image %p\n",
829 imm32, func, image);
830 return -EINVAL;
831 }
832 EMIT1_off32(0xE8, jmp_offset);
833 if (seen_ld_abs) {
834 if (reload_skb_data) {
835 EMIT1(0x5F); /* pop %rdi */
836 emit_load_skb_data_hlen(&prog);
837 } else {
838 EMIT2(0x41, 0x59); /* pop %r9 */
839 EMIT2(0x41, 0x5A); /* pop %r10 */
840 }
841 }
842 break;
843
844 case BPF_JMP | BPF_CALL | BPF_X:
845 emit_bpf_tail_call(&prog);
846 break;
847
848 /* cond jump */
849 case BPF_JMP | BPF_JEQ | BPF_X:
850 case BPF_JMP | BPF_JNE | BPF_X:
851 case BPF_JMP | BPF_JGT | BPF_X:
852 case BPF_JMP | BPF_JGE | BPF_X:
853 case BPF_JMP | BPF_JSGT | BPF_X:
854 case BPF_JMP | BPF_JSGE | BPF_X:
855 /* cmp dst_reg, src_reg */
856 EMIT3(add_2mod(0x48, dst_reg, src_reg), 0x39,
857 add_2reg(0xC0, dst_reg, src_reg));
858 goto emit_cond_jmp;
859
860 case BPF_JMP | BPF_JSET | BPF_X:
861 /* test dst_reg, src_reg */
862 EMIT3(add_2mod(0x48, dst_reg, src_reg), 0x85,
863 add_2reg(0xC0, dst_reg, src_reg));
864 goto emit_cond_jmp;
865
866 case BPF_JMP | BPF_JSET | BPF_K:
867 /* test dst_reg, imm32 */
868 EMIT1(add_1mod(0x48, dst_reg));
869 EMIT2_off32(0xF7, add_1reg(0xC0, dst_reg), imm32);
870 goto emit_cond_jmp;
871
872 case BPF_JMP | BPF_JEQ | BPF_K:
873 case BPF_JMP | BPF_JNE | BPF_K:
874 case BPF_JMP | BPF_JGT | BPF_K:
875 case BPF_JMP | BPF_JGE | BPF_K:
876 case BPF_JMP | BPF_JSGT | BPF_K:
877 case BPF_JMP | BPF_JSGE | BPF_K:
878 /* cmp dst_reg, imm8/32 */
879 EMIT1(add_1mod(0x48, dst_reg));
880
881 if (is_imm8(imm32))
882 EMIT3(0x83, add_1reg(0xF8, dst_reg), imm32);
883 else
884 EMIT2_off32(0x81, add_1reg(0xF8, dst_reg), imm32);
885
886 emit_cond_jmp: /* convert BPF opcode to x86 */
887 switch (BPF_OP(insn->code)) {
888 case BPF_JEQ:
889 jmp_cond = X86_JE;
890 break;
891 case BPF_JSET:
892 case BPF_JNE:
893 jmp_cond = X86_JNE;
894 break;
895 case BPF_JGT:
896 /* GT is unsigned '>', JA in x86 */
897 jmp_cond = X86_JA;
898 break;
899 case BPF_JGE:
900 /* GE is unsigned '>=', JAE in x86 */
901 jmp_cond = X86_JAE;
902 break;
903 case BPF_JSGT:
904 /* signed '>', GT in x86 */
905 jmp_cond = X86_JG;
906 break;
907 case BPF_JSGE:
908 /* signed '>=', GE in x86 */
909 jmp_cond = X86_JGE;
910 break;
911 default: /* to silence gcc warning */
912 return -EFAULT;
913 }
914 jmp_offset = addrs[i + insn->off] - addrs[i];
915 if (is_imm8(jmp_offset)) {
916 EMIT2(jmp_cond, jmp_offset);
917 } else if (is_simm32(jmp_offset)) {
918 EMIT2_off32(0x0F, jmp_cond + 0x10, jmp_offset);
919 } else {
920 pr_err("cond_jmp gen bug %llx\n", jmp_offset);
921 return -EFAULT;
922 }
923
924 break;
925
926 case BPF_JMP | BPF_JA:
927 jmp_offset = addrs[i + insn->off] - addrs[i];
928 if (!jmp_offset)
929 /* optimize out nop jumps */
930 break;
931 emit_jmp:
932 if (is_imm8(jmp_offset)) {
933 EMIT2(0xEB, jmp_offset);
934 } else if (is_simm32(jmp_offset)) {
935 EMIT1_off32(0xE9, jmp_offset);
936 } else {
937 pr_err("jmp gen bug %llx\n", jmp_offset);
938 return -EFAULT;
939 }
940 break;
941
942 case BPF_LD | BPF_IND | BPF_W:
943 func = sk_load_word;
944 goto common_load;
945 case BPF_LD | BPF_ABS | BPF_W:
946 func = CHOOSE_LOAD_FUNC(imm32, sk_load_word);
947 common_load:
948 ctx->seen_ld_abs = seen_ld_abs = true;
949 jmp_offset = func - (image + addrs[i]);
950 if (!func || !is_simm32(jmp_offset)) {
951 pr_err("unsupported bpf func %d addr %p image %p\n",
952 imm32, func, image);
953 return -EINVAL;
954 }
955 if (BPF_MODE(insn->code) == BPF_ABS) {
956 /* mov %esi, imm32 */
957 EMIT1_off32(0xBE, imm32);
958 } else {
959 /* mov %rsi, src_reg */
960 EMIT_mov(BPF_REG_2, src_reg);
961 if (imm32) {
962 if (is_imm8(imm32))
963 /* add %esi, imm8 */
964 EMIT3(0x83, 0xC6, imm32);
965 else
966 /* add %esi, imm32 */
967 EMIT2_off32(0x81, 0xC6, imm32);
968 }
969 }
970 /* skb pointer is in R6 (%rbx), it will be copied into
971 * %rdi if skb_copy_bits() call is necessary.
972 * sk_load_* helpers also use %r10 and %r9d.
973 * See bpf_jit.S
974 */
975 EMIT1_off32(0xE8, jmp_offset); /* call */
976 break;
977
978 case BPF_LD | BPF_IND | BPF_H:
979 func = sk_load_half;
980 goto common_load;
981 case BPF_LD | BPF_ABS | BPF_H:
982 func = CHOOSE_LOAD_FUNC(imm32, sk_load_half);
983 goto common_load;
984 case BPF_LD | BPF_IND | BPF_B:
985 func = sk_load_byte;
986 goto common_load;
987 case BPF_LD | BPF_ABS | BPF_B:
988 func = CHOOSE_LOAD_FUNC(imm32, sk_load_byte);
989 goto common_load;
990
991 case BPF_JMP | BPF_EXIT:
992 if (seen_exit) {
993 jmp_offset = ctx->cleanup_addr - addrs[i];
994 goto emit_jmp;
995 }
996 seen_exit = true;
997 /* update cleanup_addr */
998 ctx->cleanup_addr = proglen;
999 /* mov rbx, qword ptr [rbp-X] */
1000 EMIT3_off32(0x48, 0x8B, 0x9D, -STACKSIZE);
1001 /* mov r13, qword ptr [rbp-X] */
1002 EMIT3_off32(0x4C, 0x8B, 0xAD, -STACKSIZE + 8);
1003 /* mov r14, qword ptr [rbp-X] */
1004 EMIT3_off32(0x4C, 0x8B, 0xB5, -STACKSIZE + 16);
1005 /* mov r15, qword ptr [rbp-X] */
1006 EMIT3_off32(0x4C, 0x8B, 0xBD, -STACKSIZE + 24);
1007
1008 EMIT1(0xC9); /* leave */
1009 EMIT1(0xC3); /* ret */
1010 break;
1011
1012 default:
1013 /* By design x64 JIT should support all BPF instructions
1014 * This error will be seen if new instruction was added
1015 * to interpreter, but not to JIT
1016 * or if there is junk in bpf_prog
1017 */
1018 pr_err("bpf_jit: unknown opcode %02x\n", insn->code);
1019 return -EINVAL;
1020 }
1021
1022 ilen = prog - temp;
1023 if (ilen > BPF_MAX_INSN_SIZE) {
1024 pr_err("bpf_jit_compile fatal insn size error\n");
1025 return -EFAULT;
1026 }
1027
1028 if (image) {
1029 if (unlikely(proglen + ilen > oldproglen)) {
1030 pr_err("bpf_jit_compile fatal error\n");
1031 return -EFAULT;
1032 }
1033 memcpy(image + proglen, temp, ilen);
1034 }
1035 proglen += ilen;
1036 addrs[i] = proglen;
1037 prog = temp;
1038 }
1039 return proglen;
1040 }
1041
1042 void bpf_jit_compile(struct bpf_prog *prog)
1043 {
1044 }
1045
1046 void bpf_int_jit_compile(struct bpf_prog *prog)
1047 {
1048 struct bpf_binary_header *header = NULL;
1049 int proglen, oldproglen = 0;
1050 struct jit_context ctx = {};
1051 u8 *image = NULL;
1052 int *addrs;
1053 int pass;
1054 int i;
1055
1056 if (!bpf_jit_enable)
1057 return;
1058
1059 if (!prog || !prog->len)
1060 return;
1061
1062 addrs = kmalloc(prog->len * sizeof(*addrs), GFP_KERNEL);
1063 if (!addrs)
1064 return;
1065
1066 /* Before first pass, make a rough estimation of addrs[]
1067 * each bpf instruction is translated to less than 64 bytes
1068 */
1069 for (proglen = 0, i = 0; i < prog->len; i++) {
1070 proglen += 64;
1071 addrs[i] = proglen;
1072 }
1073 ctx.cleanup_addr = proglen;
1074
1075 /* JITed image shrinks with every pass and the loop iterates
1076 * until the image stops shrinking. Very large bpf programs
1077 * may converge on the last pass. In such case do one more
1078 * pass to emit the final image
1079 */
1080 for (pass = 0; pass < 10 || image; pass++) {
1081 proglen = do_jit(prog, addrs, image, oldproglen, &ctx);
1082 if (proglen <= 0) {
1083 image = NULL;
1084 if (header)
1085 bpf_jit_binary_free(header);
1086 goto out;
1087 }
1088 if (image) {
1089 if (proglen != oldproglen) {
1090 pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
1091 proglen, oldproglen);
1092 goto out;
1093 }
1094 break;
1095 }
1096 if (proglen == oldproglen) {
1097 header = bpf_jit_binary_alloc(proglen, &image,
1098 1, jit_fill_hole);
1099 if (!header)
1100 goto out;
1101 }
1102 oldproglen = proglen;
1103 }
1104
1105 if (bpf_jit_enable > 1)
1106 bpf_jit_dump(prog->len, proglen, pass + 1, image);
1107
1108 if (image) {
1109 bpf_flush_icache(header, image + proglen);
1110 set_memory_ro((unsigned long)header, header->pages);
1111 prog->bpf_func = (void *)image;
1112 prog->jited = true;
1113 }
1114 out:
1115 kfree(addrs);
1116 }
1117
1118 void bpf_jit_free(struct bpf_prog *fp)
1119 {
1120 unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
1121 struct bpf_binary_header *header = (void *)addr;
1122
1123 if (!fp->jited)
1124 goto free_filter;
1125
1126 set_memory_rw(addr, header->pages);
1127 bpf_jit_binary_free(header);
1128
1129 free_filter:
1130 bpf_prog_unlock_free(fp);
1131 }
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