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WIP FPC-III support
[linux/fpc-iii.git] / arch / x86 / net / bpf_jit_comp.c
blob796506dcfc42e86484a8eb27b69ce8a14c2776c0
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * bpf_jit_comp.c: BPF JIT compiler
4 *
5 * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com)
6 * Internal BPF Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
7 */
8 #include <linux/netdevice.h>
9 #include <linux/filter.h>
10 #include <linux/if_vlan.h>
11 #include <linux/bpf.h>
12 #include <linux/memory.h>
13 #include <linux/sort.h>
14 #include <asm/extable.h>
15 #include <asm/set_memory.h>
16 #include <asm/nospec-branch.h>
17 #include <asm/text-patching.h>
18 #include <asm/asm-prototypes.h>
19
20 static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
21 {
22 if (len == 1)
23 *ptr = bytes;
24 else if (len == 2)
25 *(u16 *)ptr = bytes;
26 else {
27 *(u32 *)ptr = bytes;
28 barrier();
29 }
30 return ptr + len;
31 }
32
33 #define EMIT(bytes, len) \
34 do { prog = emit_code(prog, bytes, len); cnt += len; } while (0)
35
36 #define EMIT1(b1) EMIT(b1, 1)
37 #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
38 #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
39 #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
40
41 #define EMIT1_off32(b1, off) \
42 do { EMIT1(b1); EMIT(off, 4); } while (0)
43 #define EMIT2_off32(b1, b2, off) \
44 do { EMIT2(b1, b2); EMIT(off, 4); } while (0)
45 #define EMIT3_off32(b1, b2, b3, off) \
46 do { EMIT3(b1, b2, b3); EMIT(off, 4); } while (0)
47 #define EMIT4_off32(b1, b2, b3, b4, off) \
48 do { EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0)
49
50 static bool is_imm8(int value)
51 {
52 return value <= 127 && value >= -128;
53 }
54
55 static bool is_simm32(s64 value)
56 {
57 return value == (s64)(s32)value;
58 }
59
60 static bool is_uimm32(u64 value)
61 {
62 return value == (u64)(u32)value;
63 }
64
65 /* mov dst, src */
66 #define EMIT_mov(DST, SRC) \
67 do { \
68 if (DST != SRC) \
69 EMIT3(add_2mod(0x48, DST, SRC), 0x89, add_2reg(0xC0, DST, SRC)); \
70 } while (0)
71
72 static int bpf_size_to_x86_bytes(int bpf_size)
73 {
74 if (bpf_size == BPF_W)
75 return 4;
76 else if (bpf_size == BPF_H)
77 return 2;
78 else if (bpf_size == BPF_B)
79 return 1;
80 else if (bpf_size == BPF_DW)
81 return 4; /* imm32 */
82 else
83 return 0;
84 }
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_JL 0x7C
97 #define X86_JGE 0x7D
98 #define X86_JLE 0x7E
99 #define X86_JG 0x7F
100
101 /* Pick a register outside of BPF range for JIT internal work */
102 #define AUX_REG (MAX_BPF_JIT_REG + 1)
103 #define X86_REG_R9 (MAX_BPF_JIT_REG + 2)
104
105 /*
106 * The following table maps BPF registers to x86-64 registers.
107 *
108 * x86-64 register R12 is unused, since if used as base address
109 * register in load/store instructions, it always needs an
110 * extra byte of encoding and is callee saved.
111 *
112 * x86-64 register R9 is not used by BPF programs, but can be used by BPF
113 * trampoline. x86-64 register R10 is used for blinding (if enabled).
114 */
115 static const int reg2hex[] = {
116 [BPF_REG_0] = 0, /* RAX */
117 [BPF_REG_1] = 7, /* RDI */
118 [BPF_REG_2] = 6, /* RSI */
119 [BPF_REG_3] = 2, /* RDX */
120 [BPF_REG_4] = 1, /* RCX */
121 [BPF_REG_5] = 0, /* R8 */
122 [BPF_REG_6] = 3, /* RBX callee saved */
123 [BPF_REG_7] = 5, /* R13 callee saved */
124 [BPF_REG_8] = 6, /* R14 callee saved */
125 [BPF_REG_9] = 7, /* R15 callee saved */
126 [BPF_REG_FP] = 5, /* RBP readonly */
127 [BPF_REG_AX] = 2, /* R10 temp register */
128 [AUX_REG] = 3, /* R11 temp register */
129 [X86_REG_R9] = 1, /* R9 register, 6th function argument */
130 };
131
132 static const int reg2pt_regs[] = {
133 [BPF_REG_0] = offsetof(struct pt_regs, ax),
134 [BPF_REG_1] = offsetof(struct pt_regs, di),
135 [BPF_REG_2] = offsetof(struct pt_regs, si),
136 [BPF_REG_3] = offsetof(struct pt_regs, dx),
137 [BPF_REG_4] = offsetof(struct pt_regs, cx),
138 [BPF_REG_5] = offsetof(struct pt_regs, r8),
139 [BPF_REG_6] = offsetof(struct pt_regs, bx),
140 [BPF_REG_7] = offsetof(struct pt_regs, r13),
141 [BPF_REG_8] = offsetof(struct pt_regs, r14),
142 [BPF_REG_9] = offsetof(struct pt_regs, r15),
143 };
144
145 /*
146 * is_ereg() == true if BPF register 'reg' maps to x86-64 r8..r15
147 * which need extra byte of encoding.
148 * rax,rcx,...,rbp have simpler encoding
149 */
150 static bool is_ereg(u32 reg)
151 {
152 return (1 << reg) & (BIT(BPF_REG_5) |
153 BIT(AUX_REG) |
154 BIT(BPF_REG_7) |
155 BIT(BPF_REG_8) |
156 BIT(BPF_REG_9) |
157 BIT(X86_REG_R9) |
158 BIT(BPF_REG_AX));
159 }
160
161 /*
162 * is_ereg_8l() == true if BPF register 'reg' is mapped to access x86-64
163 * lower 8-bit registers dil,sil,bpl,spl,r8b..r15b, which need extra byte
164 * of encoding. al,cl,dl,bl have simpler encoding.
165 */
166 static bool is_ereg_8l(u32 reg)
167 {
168 return is_ereg(reg) ||
169 (1 << reg) & (BIT(BPF_REG_1) |
170 BIT(BPF_REG_2) |
171 BIT(BPF_REG_FP));
172 }
173
174 static bool is_axreg(u32 reg)
175 {
176 return reg == BPF_REG_0;
177 }
178
179 /* Add modifiers if 'reg' maps to x86-64 registers R8..R15 */
180 static u8 add_1mod(u8 byte, u32 reg)
181 {
182 if (is_ereg(reg))
183 byte |= 1;
184 return byte;
185 }
186
187 static u8 add_2mod(u8 byte, u32 r1, u32 r2)
188 {
189 if (is_ereg(r1))
190 byte |= 1;
191 if (is_ereg(r2))
192 byte |= 4;
193 return byte;
194 }
195
196 /* Encode 'dst_reg' register into x86-64 opcode 'byte' */
197 static u8 add_1reg(u8 byte, u32 dst_reg)
198 {
199 return byte + reg2hex[dst_reg];
200 }
201
202 /* Encode 'dst_reg' and 'src_reg' registers into x86-64 opcode 'byte' */
203 static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg)
204 {
205 return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3);
206 }
207
208 static void jit_fill_hole(void *area, unsigned int size)
209 {
210 /* Fill whole space with INT3 instructions */
211 memset(area, 0xcc, size);
212 }
213
214 struct jit_context {
215 int cleanup_addr; /* Epilogue code offset */
216 };
217
218 /* Maximum number of bytes emitted while JITing one eBPF insn */
219 #define BPF_MAX_INSN_SIZE 128
220 #define BPF_INSN_SAFETY 64
221
222 /* Number of bytes emit_patch() needs to generate instructions */
223 #define X86_PATCH_SIZE 5
224 /* Number of bytes that will be skipped on tailcall */
225 #define X86_TAIL_CALL_OFFSET 11
226
227 static void push_callee_regs(u8 **pprog, bool *callee_regs_used)
228 {
229 u8 *prog = *pprog;
230 int cnt = 0;
231
232 if (callee_regs_used[0])
233 EMIT1(0x53); /* push rbx */
234 if (callee_regs_used[1])
235 EMIT2(0x41, 0x55); /* push r13 */
236 if (callee_regs_used[2])
237 EMIT2(0x41, 0x56); /* push r14 */
238 if (callee_regs_used[3])
239 EMIT2(0x41, 0x57); /* push r15 */
240 *pprog = prog;
241 }
242
243 static void pop_callee_regs(u8 **pprog, bool *callee_regs_used)
244 {
245 u8 *prog = *pprog;
246 int cnt = 0;
247
248 if (callee_regs_used[3])
249 EMIT2(0x41, 0x5F); /* pop r15 */
250 if (callee_regs_used[2])
251 EMIT2(0x41, 0x5E); /* pop r14 */
252 if (callee_regs_used[1])
253 EMIT2(0x41, 0x5D); /* pop r13 */
254 if (callee_regs_used[0])
255 EMIT1(0x5B); /* pop rbx */
256 *pprog = prog;
257 }
258
259 /*
260 * Emit x86-64 prologue code for BPF program.
261 * bpf_tail_call helper will skip the first X86_TAIL_CALL_OFFSET bytes
262 * while jumping to another program
263 */
264 static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
265 bool tail_call_reachable, bool is_subprog)
266 {
267 u8 *prog = *pprog;
268 int cnt = X86_PATCH_SIZE;
269
270 /* BPF trampoline can be made to work without these nops,
271 * but let's waste 5 bytes for now and optimize later
272 */
273 memcpy(prog, ideal_nops[NOP_ATOMIC5], cnt);
274 prog += cnt;
275 if (!ebpf_from_cbpf) {
276 if (tail_call_reachable && !is_subprog)
277 EMIT2(0x31, 0xC0); /* xor eax, eax */
278 else
279 EMIT2(0x66, 0x90); /* nop2 */
280 }
281 EMIT1(0x55); /* push rbp */
282 EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
283 /* sub rsp, rounded_stack_depth */
284 if (stack_depth)
285 EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8));
286 if (tail_call_reachable)
287 EMIT1(0x50); /* push rax */
288 *pprog = prog;
289 }
290
291 static int emit_patch(u8 **pprog, void *func, void *ip, u8 opcode)
292 {
293 u8 *prog = *pprog;
294 int cnt = 0;
295 s64 offset;
296
297 offset = func - (ip + X86_PATCH_SIZE);
298 if (!is_simm32(offset)) {
299 pr_err("Target call %p is out of range\n", func);
300 return -ERANGE;
301 }
302 EMIT1_off32(opcode, offset);
303 *pprog = prog;
304 return 0;
305 }
306
307 static int emit_call(u8 **pprog, void *func, void *ip)
308 {
309 return emit_patch(pprog, func, ip, 0xE8);
310 }
311
312 static int emit_jump(u8 **pprog, void *func, void *ip)
313 {
314 return emit_patch(pprog, func, ip, 0xE9);
315 }
316
317 static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
318 void *old_addr, void *new_addr,
319 const bool text_live)
320 {
321 const u8 *nop_insn = ideal_nops[NOP_ATOMIC5];
322 u8 old_insn[X86_PATCH_SIZE];
323 u8 new_insn[X86_PATCH_SIZE];
324 u8 *prog;
325 int ret;
326
327 memcpy(old_insn, nop_insn, X86_PATCH_SIZE);
328 if (old_addr) {
329 prog = old_insn;
330 ret = t == BPF_MOD_CALL ?
331 emit_call(&prog, old_addr, ip) :
332 emit_jump(&prog, old_addr, ip);
333 if (ret)
334 return ret;
335 }
336
337 memcpy(new_insn, nop_insn, X86_PATCH_SIZE);
338 if (new_addr) {
339 prog = new_insn;
340 ret = t == BPF_MOD_CALL ?
341 emit_call(&prog, new_addr, ip) :
342 emit_jump(&prog, new_addr, ip);
343 if (ret)
344 return ret;
345 }
346
347 ret = -EBUSY;
348 mutex_lock(&text_mutex);
349 if (memcmp(ip, old_insn, X86_PATCH_SIZE))
350 goto out;
351 ret = 1;
352 if (memcmp(ip, new_insn, X86_PATCH_SIZE)) {
353 if (text_live)
354 text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL);
355 else
356 memcpy(ip, new_insn, X86_PATCH_SIZE);
357 ret = 0;
358 }
359 out:
360 mutex_unlock(&text_mutex);
361 return ret;
362 }
363
364 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
365 void *old_addr, void *new_addr)
366 {
367 if (!is_kernel_text((long)ip) &&
368 !is_bpf_text_address((long)ip))
369 /* BPF poking in modules is not supported */
370 return -EINVAL;
371
372 return __bpf_arch_text_poke(ip, t, old_addr, new_addr, true);
373 }
374
375 static int get_pop_bytes(bool *callee_regs_used)
376 {
377 int bytes = 0;
378
379 if (callee_regs_used[3])
380 bytes += 2;
381 if (callee_regs_used[2])
382 bytes += 2;
383 if (callee_regs_used[1])
384 bytes += 2;
385 if (callee_regs_used[0])
386 bytes += 1;
387
388 return bytes;
389 }
390
391 /*
392 * Generate the following code:
393 *
394 * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
395 * if (index >= array->map.max_entries)
396 * goto out;
397 * if (++tail_call_cnt > MAX_TAIL_CALL_CNT)
398 * goto out;
399 * prog = array->ptrs[index];
400 * if (prog == NULL)
401 * goto out;
402 * goto *(prog->bpf_func + prologue_size);
403 * out:
404 */
405 static void emit_bpf_tail_call_indirect(u8 **pprog, bool *callee_regs_used,
406 u32 stack_depth)
407 {
408 int tcc_off = -4 - round_up(stack_depth, 8);
409 u8 *prog = *pprog;
410 int pop_bytes = 0;
411 int off1 = 42;
412 int off2 = 31;
413 int off3 = 9;
414 int cnt = 0;
415
416 /* count the additional bytes used for popping callee regs from stack
417 * that need to be taken into account for each of the offsets that
418 * are used for bailing out of the tail call
419 */
420 pop_bytes = get_pop_bytes(callee_regs_used);
421 off1 += pop_bytes;
422 off2 += pop_bytes;
423 off3 += pop_bytes;
424
425 if (stack_depth) {
426 off1 += 7;
427 off2 += 7;
428 off3 += 7;
429 }
430
431 /*
432 * rdi - pointer to ctx
433 * rsi - pointer to bpf_array
434 * rdx - index in bpf_array
435 */
436
437 /*
438 * if (index >= array->map.max_entries)
439 * goto out;
440 */
441 EMIT2(0x89, 0xD2); /* mov edx, edx */
442 EMIT3(0x39, 0x56, /* cmp dword ptr [rsi + 16], edx */
443 offsetof(struct bpf_array, map.max_entries));
444 #define OFFSET1 (off1 + RETPOLINE_RCX_BPF_JIT_SIZE) /* Number of bytes to jump */
445 EMIT2(X86_JBE, OFFSET1); /* jbe out */
446
447 /*
448 * if (tail_call_cnt > MAX_TAIL_CALL_CNT)
449 * goto out;
450 */
451 EMIT2_off32(0x8B, 0x85, tcc_off); /* mov eax, dword ptr [rbp - tcc_off] */
452 EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */
453 #define OFFSET2 (off2 + RETPOLINE_RCX_BPF_JIT_SIZE)
454 EMIT2(X86_JA, OFFSET2); /* ja out */
455 EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */
456 EMIT2_off32(0x89, 0x85, tcc_off); /* mov dword ptr [rbp - tcc_off], eax */
457
458 /* prog = array->ptrs[index]; */
459 EMIT4_off32(0x48, 0x8B, 0x8C, 0xD6, /* mov rcx, [rsi + rdx * 8 + offsetof(...)] */
460 offsetof(struct bpf_array, ptrs));
461
462 /*
463 * if (prog == NULL)
464 * goto out;
465 */
466 EMIT3(0x48, 0x85, 0xC9); /* test rcx,rcx */
467 #define OFFSET3 (off3 + RETPOLINE_RCX_BPF_JIT_SIZE)
468 EMIT2(X86_JE, OFFSET3); /* je out */
469
470 *pprog = prog;
471 pop_callee_regs(pprog, callee_regs_used);
472 prog = *pprog;
473
474 EMIT1(0x58); /* pop rax */
475 if (stack_depth)
476 EMIT3_off32(0x48, 0x81, 0xC4, /* add rsp, sd */
477 round_up(stack_depth, 8));
478
479 /* goto *(prog->bpf_func + X86_TAIL_CALL_OFFSET); */
480 EMIT4(0x48, 0x8B, 0x49, /* mov rcx, qword ptr [rcx + 32] */
481 offsetof(struct bpf_prog, bpf_func));
482 EMIT4(0x48, 0x83, 0xC1, /* add rcx, X86_TAIL_CALL_OFFSET */
483 X86_TAIL_CALL_OFFSET);
484 /*
485 * Now we're ready to jump into next BPF program
486 * rdi == ctx (1st arg)
487 * rcx == prog->bpf_func + X86_TAIL_CALL_OFFSET
488 */
489 RETPOLINE_RCX_BPF_JIT();
490
491 /* out: */
492 *pprog = prog;
493 }
494
495 static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke,
496 u8 **pprog, int addr, u8 *image,
497 bool *callee_regs_used, u32 stack_depth)
498 {
499 int tcc_off = -4 - round_up(stack_depth, 8);
500 u8 *prog = *pprog;
501 int pop_bytes = 0;
502 int off1 = 20;
503 int poke_off;
504 int cnt = 0;
505
506 /* count the additional bytes used for popping callee regs to stack
507 * that need to be taken into account for jump offset that is used for
508 * bailing out from of the tail call when limit is reached
509 */
510 pop_bytes = get_pop_bytes(callee_regs_used);
511 off1 += pop_bytes;
512
513 /*
514 * total bytes for:
515 * - nop5/ jmpq $off
516 * - pop callee regs
517 * - sub rsp, $val if depth > 0
518 * - pop rax
519 */
520 poke_off = X86_PATCH_SIZE + pop_bytes + 1;
521 if (stack_depth) {
522 poke_off += 7;
523 off1 += 7;
524 }
525
526 /*
527 * if (tail_call_cnt > MAX_TAIL_CALL_CNT)
528 * goto out;
529 */
530 EMIT2_off32(0x8B, 0x85, tcc_off); /* mov eax, dword ptr [rbp - tcc_off] */
531 EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */
532 EMIT2(X86_JA, off1); /* ja out */
533 EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */
534 EMIT2_off32(0x89, 0x85, tcc_off); /* mov dword ptr [rbp - tcc_off], eax */
535
536 poke->tailcall_bypass = image + (addr - poke_off - X86_PATCH_SIZE);
537 poke->adj_off = X86_TAIL_CALL_OFFSET;
538 poke->tailcall_target = image + (addr - X86_PATCH_SIZE);
539 poke->bypass_addr = (u8 *)poke->tailcall_target + X86_PATCH_SIZE;
540
541 emit_jump(&prog, (u8 *)poke->tailcall_target + X86_PATCH_SIZE,
542 poke->tailcall_bypass);
543
544 *pprog = prog;
545 pop_callee_regs(pprog, callee_regs_used);
546 prog = *pprog;
547 EMIT1(0x58); /* pop rax */
548 if (stack_depth)
549 EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8));
550
551 memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE);
552 prog += X86_PATCH_SIZE;
553 /* out: */
554
555 *pprog = prog;
556 }
557
558 static void bpf_tail_call_direct_fixup(struct bpf_prog *prog)
559 {
560 struct bpf_jit_poke_descriptor *poke;
561 struct bpf_array *array;
562 struct bpf_prog *target;
563 int i, ret;
564
565 for (i = 0; i < prog->aux->size_poke_tab; i++) {
566 poke = &prog->aux->poke_tab[i];
567 WARN_ON_ONCE(READ_ONCE(poke->tailcall_target_stable));
568
569 if (poke->reason != BPF_POKE_REASON_TAIL_CALL)
570 continue;
571
572 array = container_of(poke->tail_call.map, struct bpf_array, map);
573 mutex_lock(&array->aux->poke_mutex);
574 target = array->ptrs[poke->tail_call.key];
575 if (target) {
576 /* Plain memcpy is used when image is not live yet
577 * and still not locked as read-only. Once poke
578 * location is active (poke->tailcall_target_stable),
579 * any parallel bpf_arch_text_poke() might occur
580 * still on the read-write image until we finally
581 * locked it as read-only. Both modifications on
582 * the given image are under text_mutex to avoid
583 * interference.
584 */
585 ret = __bpf_arch_text_poke(poke->tailcall_target,
586 BPF_MOD_JUMP, NULL,
587 (u8 *)target->bpf_func +
588 poke->adj_off, false);
589 BUG_ON(ret < 0);
590 ret = __bpf_arch_text_poke(poke->tailcall_bypass,
591 BPF_MOD_JUMP,
592 (u8 *)poke->tailcall_target +
593 X86_PATCH_SIZE, NULL, false);
594 BUG_ON(ret < 0);
595 }
596 WRITE_ONCE(poke->tailcall_target_stable, true);
597 mutex_unlock(&array->aux->poke_mutex);
598 }
599 }
600
601 static void emit_mov_imm32(u8 **pprog, bool sign_propagate,
602 u32 dst_reg, const u32 imm32)
603 {
604 u8 *prog = *pprog;
605 u8 b1, b2, b3;
606 int cnt = 0;
607
608 /*
609 * Optimization: if imm32 is positive, use 'mov %eax, imm32'
610 * (which zero-extends imm32) to save 2 bytes.
611 */
612 if (sign_propagate && (s32)imm32 < 0) {
613 /* 'mov %rax, imm32' sign extends imm32 */
614 b1 = add_1mod(0x48, dst_reg);
615 b2 = 0xC7;
616 b3 = 0xC0;
617 EMIT3_off32(b1, b2, add_1reg(b3, dst_reg), imm32);
618 goto done;
619 }
620
621 /*
622 * Optimization: if imm32 is zero, use 'xor %eax, %eax'
623 * to save 3 bytes.
624 */
625 if (imm32 == 0) {
626 if (is_ereg(dst_reg))
627 EMIT1(add_2mod(0x40, dst_reg, dst_reg));
628 b2 = 0x31; /* xor */
629 b3 = 0xC0;
630 EMIT2(b2, add_2reg(b3, dst_reg, dst_reg));
631 goto done;
632 }
633
634 /* mov %eax, imm32 */
635 if (is_ereg(dst_reg))
636 EMIT1(add_1mod(0x40, dst_reg));
637 EMIT1_off32(add_1reg(0xB8, dst_reg), imm32);
638 done:
639 *pprog = prog;
640 }
641
642 static void emit_mov_imm64(u8 **pprog, u32 dst_reg,
643 const u32 imm32_hi, const u32 imm32_lo)
644 {
645 u8 *prog = *pprog;
646 int cnt = 0;
647
648 if (is_uimm32(((u64)imm32_hi << 32) | (u32)imm32_lo)) {
649 /*
650 * For emitting plain u32, where sign bit must not be
651 * propagated LLVM tends to load imm64 over mov32
652 * directly, so save couple of bytes by just doing
653 * 'mov %eax, imm32' instead.
654 */
655 emit_mov_imm32(&prog, false, dst_reg, imm32_lo);
656 } else {
657 /* movabsq %rax, imm64 */
658 EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg));
659 EMIT(imm32_lo, 4);
660 EMIT(imm32_hi, 4);
661 }
662
663 *pprog = prog;
664 }
665
666 static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg)
667 {
668 u8 *prog = *pprog;
669 int cnt = 0;
670
671 if (is64) {
672 /* mov dst, src */
673 EMIT_mov(dst_reg, src_reg);
674 } else {
675 /* mov32 dst, src */
676 if (is_ereg(dst_reg) || is_ereg(src_reg))
677 EMIT1(add_2mod(0x40, dst_reg, src_reg));
678 EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg));
679 }
680
681 *pprog = prog;
682 }
683
684 /* LDX: dst_reg = *(u8*)(src_reg + off) */
685 static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
686 {
687 u8 *prog = *pprog;
688 int cnt = 0;
689
690 switch (size) {
691 case BPF_B:
692 /* Emit 'movzx rax, byte ptr [rax + off]' */
693 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6);
694 break;
695 case BPF_H:
696 /* Emit 'movzx rax, word ptr [rax + off]' */
697 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7);
698 break;
699 case BPF_W:
700 /* Emit 'mov eax, dword ptr [rax+0x14]' */
701 if (is_ereg(dst_reg) || is_ereg(src_reg))
702 EMIT2(add_2mod(0x40, src_reg, dst_reg), 0x8B);
703 else
704 EMIT1(0x8B);
705 break;
706 case BPF_DW:
707 /* Emit 'mov rax, qword ptr [rax+0x14]' */
708 EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B);
709 break;
710 }
711 /*
712 * If insn->off == 0 we can save one extra byte, but
713 * special case of x86 R13 which always needs an offset
714 * is not worth the hassle
715 */
716 if (is_imm8(off))
717 EMIT2(add_2reg(0x40, src_reg, dst_reg), off);
718 else
719 EMIT1_off32(add_2reg(0x80, src_reg, dst_reg), off);
720 *pprog = prog;
721 }
722
723 /* STX: *(u8*)(dst_reg + off) = src_reg */
724 static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
725 {
726 u8 *prog = *pprog;
727 int cnt = 0;
728
729 switch (size) {
730 case BPF_B:
731 /* Emit 'mov byte ptr [rax + off], al' */
732 if (is_ereg(dst_reg) || is_ereg_8l(src_reg))
733 /* Add extra byte for eregs or SIL,DIL,BPL in src_reg */
734 EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88);
735 else
736 EMIT1(0x88);
737 break;
738 case BPF_H:
739 if (is_ereg(dst_reg) || is_ereg(src_reg))
740 EMIT3(0x66, add_2mod(0x40, dst_reg, src_reg), 0x89);
741 else
742 EMIT2(0x66, 0x89);
743 break;
744 case BPF_W:
745 if (is_ereg(dst_reg) || is_ereg(src_reg))
746 EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89);
747 else
748 EMIT1(0x89);
749 break;
750 case BPF_DW:
751 EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89);
752 break;
753 }
754 if (is_imm8(off))
755 EMIT2(add_2reg(0x40, dst_reg, src_reg), off);
756 else
757 EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), off);
758 *pprog = prog;
759 }
760
761 static bool ex_handler_bpf(const struct exception_table_entry *x,
762 struct pt_regs *regs, int trapnr,
763 unsigned long error_code, unsigned long fault_addr)
764 {
765 u32 reg = x->fixup >> 8;
766
767 /* jump over faulting load and clear dest register */
768 *(unsigned long *)((void *)regs + reg) = 0;
769 regs->ip += x->fixup & 0xff;
770 return true;
771 }
772
773 static void detect_reg_usage(struct bpf_insn *insn, int insn_cnt,
774 bool *regs_used, bool *tail_call_seen)
775 {
776 int i;
777
778 for (i = 1; i <= insn_cnt; i++, insn++) {
779 if (insn->code == (BPF_JMP | BPF_TAIL_CALL))
780 *tail_call_seen = true;
781 if (insn->dst_reg == BPF_REG_6 || insn->src_reg == BPF_REG_6)
782 regs_used[0] = true;
783 if (insn->dst_reg == BPF_REG_7 || insn->src_reg == BPF_REG_7)
784 regs_used[1] = true;
785 if (insn->dst_reg == BPF_REG_8 || insn->src_reg == BPF_REG_8)
786 regs_used[2] = true;
787 if (insn->dst_reg == BPF_REG_9 || insn->src_reg == BPF_REG_9)
788 regs_used[3] = true;
789 }
790 }
791
792 static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
793 int oldproglen, struct jit_context *ctx)
794 {
795 bool tail_call_reachable = bpf_prog->aux->tail_call_reachable;
796 struct bpf_insn *insn = bpf_prog->insnsi;
797 bool callee_regs_used[4] = {};
798 int insn_cnt = bpf_prog->len;
799 bool tail_call_seen = false;
800 bool seen_exit = false;
801 u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY];
802 int i, cnt = 0, excnt = 0;
803 int proglen = 0;
804 u8 *prog = temp;
805
806 detect_reg_usage(insn, insn_cnt, callee_regs_used,
807 &tail_call_seen);
808
809 /* tail call's presence in current prog implies it is reachable */
810 tail_call_reachable |= tail_call_seen;
811
812 emit_prologue(&prog, bpf_prog->aux->stack_depth,
813 bpf_prog_was_classic(bpf_prog), tail_call_reachable,
814 bpf_prog->aux->func_idx != 0);
815 push_callee_regs(&prog, callee_regs_used);
816 addrs[0] = prog - temp;
817
818 for (i = 1; i <= insn_cnt; i++, insn++) {
819 const s32 imm32 = insn->imm;
820 u32 dst_reg = insn->dst_reg;
821 u32 src_reg = insn->src_reg;
822 u8 b2 = 0, b3 = 0;
823 s64 jmp_offset;
824 u8 jmp_cond;
825 int ilen;
826 u8 *func;
827
828 switch (insn->code) {
829 /* ALU */
830 case BPF_ALU | BPF_ADD | BPF_X:
831 case BPF_ALU | BPF_SUB | BPF_X:
832 case BPF_ALU | BPF_AND | BPF_X:
833 case BPF_ALU | BPF_OR | BPF_X:
834 case BPF_ALU | BPF_XOR | BPF_X:
835 case BPF_ALU64 | BPF_ADD | BPF_X:
836 case BPF_ALU64 | BPF_SUB | BPF_X:
837 case BPF_ALU64 | BPF_AND | BPF_X:
838 case BPF_ALU64 | BPF_OR | BPF_X:
839 case BPF_ALU64 | BPF_XOR | BPF_X:
840 switch (BPF_OP(insn->code)) {
841 case BPF_ADD: b2 = 0x01; break;
842 case BPF_SUB: b2 = 0x29; break;
843 case BPF_AND: b2 = 0x21; break;
844 case BPF_OR: b2 = 0x09; break;
845 case BPF_XOR: b2 = 0x31; break;
846 }
847 if (BPF_CLASS(insn->code) == BPF_ALU64)
848 EMIT1(add_2mod(0x48, dst_reg, src_reg));
849 else if (is_ereg(dst_reg) || is_ereg(src_reg))
850 EMIT1(add_2mod(0x40, dst_reg, src_reg));
851 EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg));
852 break;
853
854 case BPF_ALU64 | BPF_MOV | BPF_X:
855 case BPF_ALU | BPF_MOV | BPF_X:
856 emit_mov_reg(&prog,
857 BPF_CLASS(insn->code) == BPF_ALU64,
858 dst_reg, src_reg);
859 break;
860
861 /* neg dst */
862 case BPF_ALU | BPF_NEG:
863 case BPF_ALU64 | BPF_NEG:
864 if (BPF_CLASS(insn->code) == BPF_ALU64)
865 EMIT1(add_1mod(0x48, dst_reg));
866 else if (is_ereg(dst_reg))
867 EMIT1(add_1mod(0x40, dst_reg));
868 EMIT2(0xF7, add_1reg(0xD8, dst_reg));
869 break;
870
871 case BPF_ALU | BPF_ADD | BPF_K:
872 case BPF_ALU | BPF_SUB | BPF_K:
873 case BPF_ALU | BPF_AND | BPF_K:
874 case BPF_ALU | BPF_OR | BPF_K:
875 case BPF_ALU | BPF_XOR | BPF_K:
876 case BPF_ALU64 | BPF_ADD | BPF_K:
877 case BPF_ALU64 | BPF_SUB | BPF_K:
878 case BPF_ALU64 | BPF_AND | BPF_K:
879 case BPF_ALU64 | BPF_OR | BPF_K:
880 case BPF_ALU64 | BPF_XOR | BPF_K:
881 if (BPF_CLASS(insn->code) == BPF_ALU64)
882 EMIT1(add_1mod(0x48, dst_reg));
883 else if (is_ereg(dst_reg))
884 EMIT1(add_1mod(0x40, dst_reg));
885
886 /*
887 * b3 holds 'normal' opcode, b2 short form only valid
888 * in case dst is eax/rax.
889 */
890 switch (BPF_OP(insn->code)) {
891 case BPF_ADD:
892 b3 = 0xC0;
893 b2 = 0x05;
894 break;
895 case BPF_SUB:
896 b3 = 0xE8;
897 b2 = 0x2D;
898 break;
899 case BPF_AND:
900 b3 = 0xE0;
901 b2 = 0x25;
902 break;
903 case BPF_OR:
904 b3 = 0xC8;
905 b2 = 0x0D;
906 break;
907 case BPF_XOR:
908 b3 = 0xF0;
909 b2 = 0x35;
910 break;
911 }
912
913 if (is_imm8(imm32))
914 EMIT3(0x83, add_1reg(b3, dst_reg), imm32);
915 else if (is_axreg(dst_reg))
916 EMIT1_off32(b2, imm32);
917 else
918 EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32);
919 break;
920
921 case BPF_ALU64 | BPF_MOV | BPF_K:
922 case BPF_ALU | BPF_MOV | BPF_K:
923 emit_mov_imm32(&prog, BPF_CLASS(insn->code) == BPF_ALU64,
924 dst_reg, imm32);
925 break;
926
927 case BPF_LD | BPF_IMM | BPF_DW:
928 emit_mov_imm64(&prog, dst_reg, insn[1].imm, insn[0].imm);
929 insn++;
930 i++;
931 break;
932
933 /* dst %= src, dst /= src, dst %= imm32, dst /= imm32 */
934 case BPF_ALU | BPF_MOD | BPF_X:
935 case BPF_ALU | BPF_DIV | BPF_X:
936 case BPF_ALU | BPF_MOD | BPF_K:
937 case BPF_ALU | BPF_DIV | BPF_K:
938 case BPF_ALU64 | BPF_MOD | BPF_X:
939 case BPF_ALU64 | BPF_DIV | BPF_X:
940 case BPF_ALU64 | BPF_MOD | BPF_K:
941 case BPF_ALU64 | BPF_DIV | BPF_K:
942 EMIT1(0x50); /* push rax */
943 EMIT1(0x52); /* push rdx */
944
945 if (BPF_SRC(insn->code) == BPF_X)
946 /* mov r11, src_reg */
947 EMIT_mov(AUX_REG, src_reg);
948 else
949 /* mov r11, imm32 */
950 EMIT3_off32(0x49, 0xC7, 0xC3, imm32);
951
952 /* mov rax, dst_reg */
953 EMIT_mov(BPF_REG_0, dst_reg);
954
955 /*
956 * xor edx, edx
957 * equivalent to 'xor rdx, rdx', but one byte less
958 */
959 EMIT2(0x31, 0xd2);
960
961 if (BPF_CLASS(insn->code) == BPF_ALU64)
962 /* div r11 */
963 EMIT3(0x49, 0xF7, 0xF3);
964 else
965 /* div r11d */
966 EMIT3(0x41, 0xF7, 0xF3);
967
968 if (BPF_OP(insn->code) == BPF_MOD)
969 /* mov r11, rdx */
970 EMIT3(0x49, 0x89, 0xD3);
971 else
972 /* mov r11, rax */
973 EMIT3(0x49, 0x89, 0xC3);
974
975 EMIT1(0x5A); /* pop rdx */
976 EMIT1(0x58); /* pop rax */
977
978 /* mov dst_reg, r11 */
979 EMIT_mov(dst_reg, AUX_REG);
980 break;
981
982 case BPF_ALU | BPF_MUL | BPF_K:
983 case BPF_ALU | BPF_MUL | BPF_X:
984 case BPF_ALU64 | BPF_MUL | BPF_K:
985 case BPF_ALU64 | BPF_MUL | BPF_X:
986 {
987 bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
988
989 if (dst_reg != BPF_REG_0)
990 EMIT1(0x50); /* push rax */
991 if (dst_reg != BPF_REG_3)
992 EMIT1(0x52); /* push rdx */
993
994 /* mov r11, dst_reg */
995 EMIT_mov(AUX_REG, dst_reg);
996
997 if (BPF_SRC(insn->code) == BPF_X)
998 emit_mov_reg(&prog, is64, BPF_REG_0, src_reg);
999 else
1000 emit_mov_imm32(&prog, is64, BPF_REG_0, imm32);
1001
1002 if (is64)
1003 EMIT1(add_1mod(0x48, AUX_REG));
1004 else if (is_ereg(AUX_REG))
1005 EMIT1(add_1mod(0x40, AUX_REG));
1006 /* mul(q) r11 */
1007 EMIT2(0xF7, add_1reg(0xE0, AUX_REG));
1008
1009 if (dst_reg != BPF_REG_3)
1010 EMIT1(0x5A); /* pop rdx */
1011 if (dst_reg != BPF_REG_0) {
1012 /* mov dst_reg, rax */
1013 EMIT_mov(dst_reg, BPF_REG_0);
1014 EMIT1(0x58); /* pop rax */
1015 }
1016 break;
1017 }
1018 /* Shifts */
1019 case BPF_ALU | BPF_LSH | BPF_K:
1020 case BPF_ALU | BPF_RSH | BPF_K:
1021 case BPF_ALU | BPF_ARSH | BPF_K:
1022 case BPF_ALU64 | BPF_LSH | BPF_K:
1023 case BPF_ALU64 | BPF_RSH | BPF_K:
1024 case BPF_ALU64 | BPF_ARSH | BPF_K:
1025 if (BPF_CLASS(insn->code) == BPF_ALU64)
1026 EMIT1(add_1mod(0x48, dst_reg));
1027 else if (is_ereg(dst_reg))
1028 EMIT1(add_1mod(0x40, dst_reg));
1029
1030 switch (BPF_OP(insn->code)) {
1031 case BPF_LSH: b3 = 0xE0; break;
1032 case BPF_RSH: b3 = 0xE8; break;
1033 case BPF_ARSH: b3 = 0xF8; break;
1034 }
1035
1036 if (imm32 == 1)
1037 EMIT2(0xD1, add_1reg(b3, dst_reg));
1038 else
1039 EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
1040 break;
1041
1042 case BPF_ALU | BPF_LSH | BPF_X:
1043 case BPF_ALU | BPF_RSH | BPF_X:
1044 case BPF_ALU | BPF_ARSH | BPF_X:
1045 case BPF_ALU64 | BPF_LSH | BPF_X:
1046 case BPF_ALU64 | BPF_RSH | BPF_X:
1047 case BPF_ALU64 | BPF_ARSH | BPF_X:
1048
1049 /* Check for bad case when dst_reg == rcx */
1050 if (dst_reg == BPF_REG_4) {
1051 /* mov r11, dst_reg */
1052 EMIT_mov(AUX_REG, dst_reg);
1053 dst_reg = AUX_REG;
1054 }
1055
1056 if (src_reg != BPF_REG_4) { /* common case */
1057 EMIT1(0x51); /* push rcx */
1058
1059 /* mov rcx, src_reg */
1060 EMIT_mov(BPF_REG_4, src_reg);
1061 }
1062
1063 /* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */
1064 if (BPF_CLASS(insn->code) == BPF_ALU64)
1065 EMIT1(add_1mod(0x48, dst_reg));
1066 else if (is_ereg(dst_reg))
1067 EMIT1(add_1mod(0x40, dst_reg));
1068
1069 switch (BPF_OP(insn->code)) {
1070 case BPF_LSH: b3 = 0xE0; break;
1071 case BPF_RSH: b3 = 0xE8; break;
1072 case BPF_ARSH: b3 = 0xF8; break;
1073 }
1074 EMIT2(0xD3, add_1reg(b3, dst_reg));
1075
1076 if (src_reg != BPF_REG_4)
1077 EMIT1(0x59); /* pop rcx */
1078
1079 if (insn->dst_reg == BPF_REG_4)
1080 /* mov dst_reg, r11 */
1081 EMIT_mov(insn->dst_reg, AUX_REG);
1082 break;
1083
1084 case BPF_ALU | BPF_END | BPF_FROM_BE:
1085 switch (imm32) {
1086 case 16:
1087 /* Emit 'ror %ax, 8' to swap lower 2 bytes */
1088 EMIT1(0x66);
1089 if (is_ereg(dst_reg))
1090 EMIT1(0x41);
1091 EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8);
1092
1093 /* Emit 'movzwl eax, ax' */
1094 if (is_ereg(dst_reg))
1095 EMIT3(0x45, 0x0F, 0xB7);
1096 else
1097 EMIT2(0x0F, 0xB7);
1098 EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
1099 break;
1100 case 32:
1101 /* Emit 'bswap eax' to swap lower 4 bytes */
1102 if (is_ereg(dst_reg))
1103 EMIT2(0x41, 0x0F);
1104 else
1105 EMIT1(0x0F);
1106 EMIT1(add_1reg(0xC8, dst_reg));
1107 break;
1108 case 64:
1109 /* Emit 'bswap rax' to swap 8 bytes */
1110 EMIT3(add_1mod(0x48, dst_reg), 0x0F,
1111 add_1reg(0xC8, dst_reg));
1112 break;
1113 }
1114 break;
1115
1116 case BPF_ALU | BPF_END | BPF_FROM_LE:
1117 switch (imm32) {
1118 case 16:
1119 /*
1120 * Emit 'movzwl eax, ax' to zero extend 16-bit
1121 * into 64 bit
1122 */
1123 if (is_ereg(dst_reg))
1124 EMIT3(0x45, 0x0F, 0xB7);
1125 else
1126 EMIT2(0x0F, 0xB7);
1127 EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
1128 break;
1129 case 32:
1130 /* Emit 'mov eax, eax' to clear upper 32-bits */
1131 if (is_ereg(dst_reg))
1132 EMIT1(0x45);
1133 EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg));
1134 break;
1135 case 64:
1136 /* nop */
1137 break;
1138 }
1139 break;
1140
1141 /* ST: *(u8*)(dst_reg + off) = imm */
1142 case BPF_ST | BPF_MEM | BPF_B:
1143 if (is_ereg(dst_reg))
1144 EMIT2(0x41, 0xC6);
1145 else
1146 EMIT1(0xC6);
1147 goto st;
1148 case BPF_ST | BPF_MEM | BPF_H:
1149 if (is_ereg(dst_reg))
1150 EMIT3(0x66, 0x41, 0xC7);
1151 else
1152 EMIT2(0x66, 0xC7);
1153 goto st;
1154 case BPF_ST | BPF_MEM | BPF_W:
1155 if (is_ereg(dst_reg))
1156 EMIT2(0x41, 0xC7);
1157 else
1158 EMIT1(0xC7);
1159 goto st;
1160 case BPF_ST | BPF_MEM | BPF_DW:
1161 EMIT2(add_1mod(0x48, dst_reg), 0xC7);
1162
1163 st: if (is_imm8(insn->off))
1164 EMIT2(add_1reg(0x40, dst_reg), insn->off);
1165 else
1166 EMIT1_off32(add_1reg(0x80, dst_reg), insn->off);
1167
1168 EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(insn->code)));
1169 break;
1170
1171 /* STX: *(u8*)(dst_reg + off) = src_reg */
1172 case BPF_STX | BPF_MEM | BPF_B:
1173 case BPF_STX | BPF_MEM | BPF_H:
1174 case BPF_STX | BPF_MEM | BPF_W:
1175 case BPF_STX | BPF_MEM | BPF_DW:
1176 emit_stx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
1177 break;
1178
1179 /* LDX: dst_reg = *(u8*)(src_reg + off) */
1180 case BPF_LDX | BPF_MEM | BPF_B:
1181 case BPF_LDX | BPF_PROBE_MEM | BPF_B:
1182 case BPF_LDX | BPF_MEM | BPF_H:
1183 case BPF_LDX | BPF_PROBE_MEM | BPF_H:
1184 case BPF_LDX | BPF_MEM | BPF_W:
1185 case BPF_LDX | BPF_PROBE_MEM | BPF_W:
1186 case BPF_LDX | BPF_MEM | BPF_DW:
1187 case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
1188 emit_ldx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
1189 if (BPF_MODE(insn->code) == BPF_PROBE_MEM) {
1190 struct exception_table_entry *ex;
1191 u8 *_insn = image + proglen;
1192 s64 delta;
1193
1194 if (!bpf_prog->aux->extable)
1195 break;
1196
1197 if (excnt >= bpf_prog->aux->num_exentries) {
1198 pr_err("ex gen bug\n");
1199 return -EFAULT;
1200 }
1201 ex = &bpf_prog->aux->extable[excnt++];
1202
1203 delta = _insn - (u8 *)&ex->insn;
1204 if (!is_simm32(delta)) {
1205 pr_err("extable->insn doesn't fit into 32-bit\n");
1206 return -EFAULT;
1207 }
1208 ex->insn = delta;
1209
1210 delta = (u8 *)ex_handler_bpf - (u8 *)&ex->handler;
1211 if (!is_simm32(delta)) {
1212 pr_err("extable->handler doesn't fit into 32-bit\n");
1213 return -EFAULT;
1214 }
1215 ex->handler = delta;
1216
1217 if (dst_reg > BPF_REG_9) {
1218 pr_err("verifier error\n");
1219 return -EFAULT;
1220 }
1221 /*
1222 * Compute size of x86 insn and its target dest x86 register.
1223 * ex_handler_bpf() will use lower 8 bits to adjust
1224 * pt_regs->ip to jump over this x86 instruction
1225 * and upper bits to figure out which pt_regs to zero out.
1226 * End result: x86 insn "mov rbx, qword ptr [rax+0x14]"
1227 * of 4 bytes will be ignored and rbx will be zero inited.
1228 */
1229 ex->fixup = (prog - temp) | (reg2pt_regs[dst_reg] << 8);
1230 }
1231 break;
1232
1233 /* STX XADD: lock *(u32*)(dst_reg + off) += src_reg */
1234 case BPF_STX | BPF_XADD | BPF_W:
1235 /* Emit 'lock add dword ptr [rax + off], eax' */
1236 if (is_ereg(dst_reg) || is_ereg(src_reg))
1237 EMIT3(0xF0, add_2mod(0x40, dst_reg, src_reg), 0x01);
1238 else
1239 EMIT2(0xF0, 0x01);
1240 goto xadd;
1241 case BPF_STX | BPF_XADD | BPF_DW:
1242 EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01);
1243 xadd: if (is_imm8(insn->off))
1244 EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off);
1245 else
1246 EMIT1_off32(add_2reg(0x80, dst_reg, src_reg),
1247 insn->off);
1248 break;
1249
1250 /* call */
1251 case BPF_JMP | BPF_CALL:
1252 func = (u8 *) __bpf_call_base + imm32;
1253 if (tail_call_reachable) {
1254 EMIT3_off32(0x48, 0x8B, 0x85,
1255 -(bpf_prog->aux->stack_depth + 8));
1256 if (!imm32 || emit_call(&prog, func, image + addrs[i - 1] + 7))
1257 return -EINVAL;
1258 } else {
1259 if (!imm32 || emit_call(&prog, func, image + addrs[i - 1]))
1260 return -EINVAL;
1261 }
1262 break;
1263
1264 case BPF_JMP | BPF_TAIL_CALL:
1265 if (imm32)
1266 emit_bpf_tail_call_direct(&bpf_prog->aux->poke_tab[imm32 - 1],
1267 &prog, addrs[i], image,
1268 callee_regs_used,
1269 bpf_prog->aux->stack_depth);
1270 else
1271 emit_bpf_tail_call_indirect(&prog,
1272 callee_regs_used,
1273 bpf_prog->aux->stack_depth);
1274 break;
1275
1276 /* cond jump */
1277 case BPF_JMP | BPF_JEQ | BPF_X:
1278 case BPF_JMP | BPF_JNE | BPF_X:
1279 case BPF_JMP | BPF_JGT | BPF_X:
1280 case BPF_JMP | BPF_JLT | BPF_X:
1281 case BPF_JMP | BPF_JGE | BPF_X:
1282 case BPF_JMP | BPF_JLE | BPF_X:
1283 case BPF_JMP | BPF_JSGT | BPF_X:
1284 case BPF_JMP | BPF_JSLT | BPF_X:
1285 case BPF_JMP | BPF_JSGE | BPF_X:
1286 case BPF_JMP | BPF_JSLE | BPF_X:
1287 case BPF_JMP32 | BPF_JEQ | BPF_X:
1288 case BPF_JMP32 | BPF_JNE | BPF_X:
1289 case BPF_JMP32 | BPF_JGT | BPF_X:
1290 case BPF_JMP32 | BPF_JLT | BPF_X:
1291 case BPF_JMP32 | BPF_JGE | BPF_X:
1292 case BPF_JMP32 | BPF_JLE | BPF_X:
1293 case BPF_JMP32 | BPF_JSGT | BPF_X:
1294 case BPF_JMP32 | BPF_JSLT | BPF_X:
1295 case BPF_JMP32 | BPF_JSGE | BPF_X:
1296 case BPF_JMP32 | BPF_JSLE | BPF_X:
1297 /* cmp dst_reg, src_reg */
1298 if (BPF_CLASS(insn->code) == BPF_JMP)
1299 EMIT1(add_2mod(0x48, dst_reg, src_reg));
1300 else if (is_ereg(dst_reg) || is_ereg(src_reg))
1301 EMIT1(add_2mod(0x40, dst_reg, src_reg));
1302 EMIT2(0x39, add_2reg(0xC0, dst_reg, src_reg));
1303 goto emit_cond_jmp;
1304
1305 case BPF_JMP | BPF_JSET | BPF_X:
1306 case BPF_JMP32 | BPF_JSET | BPF_X:
1307 /* test dst_reg, src_reg */
1308 if (BPF_CLASS(insn->code) == BPF_JMP)
1309 EMIT1(add_2mod(0x48, dst_reg, src_reg));
1310 else if (is_ereg(dst_reg) || is_ereg(src_reg))
1311 EMIT1(add_2mod(0x40, dst_reg, src_reg));
1312 EMIT2(0x85, add_2reg(0xC0, dst_reg, src_reg));
1313 goto emit_cond_jmp;
1314
1315 case BPF_JMP | BPF_JSET | BPF_K:
1316 case BPF_JMP32 | BPF_JSET | BPF_K:
1317 /* test dst_reg, imm32 */
1318 if (BPF_CLASS(insn->code) == BPF_JMP)
1319 EMIT1(add_1mod(0x48, dst_reg));
1320 else if (is_ereg(dst_reg))
1321 EMIT1(add_1mod(0x40, dst_reg));
1322 EMIT2_off32(0xF7, add_1reg(0xC0, dst_reg), imm32);
1323 goto emit_cond_jmp;
1324
1325 case BPF_JMP | BPF_JEQ | BPF_K:
1326 case BPF_JMP | BPF_JNE | BPF_K:
1327 case BPF_JMP | BPF_JGT | BPF_K:
1328 case BPF_JMP | BPF_JLT | BPF_K:
1329 case BPF_JMP | BPF_JGE | BPF_K:
1330 case BPF_JMP | BPF_JLE | BPF_K:
1331 case BPF_JMP | BPF_JSGT | BPF_K:
1332 case BPF_JMP | BPF_JSLT | BPF_K:
1333 case BPF_JMP | BPF_JSGE | BPF_K:
1334 case BPF_JMP | BPF_JSLE | BPF_K:
1335 case BPF_JMP32 | BPF_JEQ | BPF_K:
1336 case BPF_JMP32 | BPF_JNE | BPF_K:
1337 case BPF_JMP32 | BPF_JGT | BPF_K:
1338 case BPF_JMP32 | BPF_JLT | BPF_K:
1339 case BPF_JMP32 | BPF_JGE | BPF_K:
1340 case BPF_JMP32 | BPF_JLE | BPF_K:
1341 case BPF_JMP32 | BPF_JSGT | BPF_K:
1342 case BPF_JMP32 | BPF_JSLT | BPF_K:
1343 case BPF_JMP32 | BPF_JSGE | BPF_K:
1344 case BPF_JMP32 | BPF_JSLE | BPF_K:
1345 /* test dst_reg, dst_reg to save one extra byte */
1346 if (imm32 == 0) {
1347 if (BPF_CLASS(insn->code) == BPF_JMP)
1348 EMIT1(add_2mod(0x48, dst_reg, dst_reg));
1349 else if (is_ereg(dst_reg))
1350 EMIT1(add_2mod(0x40, dst_reg, dst_reg));
1351 EMIT2(0x85, add_2reg(0xC0, dst_reg, dst_reg));
1352 goto emit_cond_jmp;
1353 }
1354
1355 /* cmp dst_reg, imm8/32 */
1356 if (BPF_CLASS(insn->code) == BPF_JMP)
1357 EMIT1(add_1mod(0x48, dst_reg));
1358 else if (is_ereg(dst_reg))
1359 EMIT1(add_1mod(0x40, dst_reg));
1360
1361 if (is_imm8(imm32))
1362 EMIT3(0x83, add_1reg(0xF8, dst_reg), imm32);
1363 else
1364 EMIT2_off32(0x81, add_1reg(0xF8, dst_reg), imm32);
1365
1366 emit_cond_jmp: /* Convert BPF opcode to x86 */
1367 switch (BPF_OP(insn->code)) {
1368 case BPF_JEQ:
1369 jmp_cond = X86_JE;
1370 break;
1371 case BPF_JSET:
1372 case BPF_JNE:
1373 jmp_cond = X86_JNE;
1374 break;
1375 case BPF_JGT:
1376 /* GT is unsigned '>', JA in x86 */
1377 jmp_cond = X86_JA;
1378 break;
1379 case BPF_JLT:
1380 /* LT is unsigned '<', JB in x86 */
1381 jmp_cond = X86_JB;
1382 break;
1383 case BPF_JGE:
1384 /* GE is unsigned '>=', JAE in x86 */
1385 jmp_cond = X86_JAE;
1386 break;
1387 case BPF_JLE:
1388 /* LE is unsigned '<=', JBE in x86 */
1389 jmp_cond = X86_JBE;
1390 break;
1391 case BPF_JSGT:
1392 /* Signed '>', GT in x86 */
1393 jmp_cond = X86_JG;
1394 break;
1395 case BPF_JSLT:
1396 /* Signed '<', LT in x86 */
1397 jmp_cond = X86_JL;
1398 break;
1399 case BPF_JSGE:
1400 /* Signed '>=', GE in x86 */
1401 jmp_cond = X86_JGE;
1402 break;
1403 case BPF_JSLE:
1404 /* Signed '<=', LE in x86 */
1405 jmp_cond = X86_JLE;
1406 break;
1407 default: /* to silence GCC warning */
1408 return -EFAULT;
1409 }
1410 jmp_offset = addrs[i + insn->off] - addrs[i];
1411 if (is_imm8(jmp_offset)) {
1412 EMIT2(jmp_cond, jmp_offset);
1413 } else if (is_simm32(jmp_offset)) {
1414 EMIT2_off32(0x0F, jmp_cond + 0x10, jmp_offset);
1415 } else {
1416 pr_err("cond_jmp gen bug %llx\n", jmp_offset);
1417 return -EFAULT;
1418 }
1419
1420 break;
1421
1422 case BPF_JMP | BPF_JA:
1423 if (insn->off == -1)
1424 /* -1 jmp instructions will always jump
1425 * backwards two bytes. Explicitly handling
1426 * this case avoids wasting too many passes
1427 * when there are long sequences of replaced
1428 * dead code.
1429 */
1430 jmp_offset = -2;
1431 else
1432 jmp_offset = addrs[i + insn->off] - addrs[i];
1433
1434 if (!jmp_offset)
1435 /* Optimize out nop jumps */
1436 break;
1437 emit_jmp:
1438 if (is_imm8(jmp_offset)) {
1439 EMIT2(0xEB, jmp_offset);
1440 } else if (is_simm32(jmp_offset)) {
1441 EMIT1_off32(0xE9, jmp_offset);
1442 } else {
1443 pr_err("jmp gen bug %llx\n", jmp_offset);
1444 return -EFAULT;
1445 }
1446 break;
1447
1448 case BPF_JMP | BPF_EXIT:
1449 if (seen_exit) {
1450 jmp_offset = ctx->cleanup_addr - addrs[i];
1451 goto emit_jmp;
1452 }
1453 seen_exit = true;
1454 /* Update cleanup_addr */
1455 ctx->cleanup_addr = proglen;
1456 pop_callee_regs(&prog, callee_regs_used);
1457 EMIT1(0xC9); /* leave */
1458 EMIT1(0xC3); /* ret */
1459 break;
1460
1461 default:
1462 /*
1463 * By design x86-64 JIT should support all BPF instructions.
1464 * This error will be seen if new instruction was added
1465 * to the interpreter, but not to the JIT, or if there is
1466 * junk in bpf_prog.
1467 */
1468 pr_err("bpf_jit: unknown opcode %02x\n", insn->code);
1469 return -EINVAL;
1470 }
1471
1472 ilen = prog - temp;
1473 if (ilen > BPF_MAX_INSN_SIZE) {
1474 pr_err("bpf_jit: fatal insn size error\n");
1475 return -EFAULT;
1476 }
1477
1478 if (image) {
1479 if (unlikely(proglen + ilen > oldproglen)) {
1480 pr_err("bpf_jit: fatal error\n");
1481 return -EFAULT;
1482 }
1483 memcpy(image + proglen, temp, ilen);
1484 }
1485 proglen += ilen;
1486 addrs[i] = proglen;
1487 prog = temp;
1488 }
1489
1490 if (image && excnt != bpf_prog->aux->num_exentries) {
1491 pr_err("extable is not populated\n");
1492 return -EFAULT;
1493 }
1494 return proglen;
1495 }
1496
1497 static void save_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
1498 int stack_size)
1499 {
1500 int i;
1501 /* Store function arguments to stack.
1502 * For a function that accepts two pointers the sequence will be:
1503 * mov QWORD PTR [rbp-0x10],rdi
1504 * mov QWORD PTR [rbp-0x8],rsi
1505 */
1506 for (i = 0; i < min(nr_args, 6); i++)
1507 emit_stx(prog, bytes_to_bpf_size(m->arg_size[i]),
1508 BPF_REG_FP,
1509 i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
1510 -(stack_size - i * 8));
1511 }
1512
1513 static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
1514 int stack_size)
1515 {
1516 int i;
1517
1518 /* Restore function arguments from stack.
1519 * For a function that accepts two pointers the sequence will be:
1520 * EMIT4(0x48, 0x8B, 0x7D, 0xF0); mov rdi,QWORD PTR [rbp-0x10]
1521 * EMIT4(0x48, 0x8B, 0x75, 0xF8); mov rsi,QWORD PTR [rbp-0x8]
1522 */
1523 for (i = 0; i < min(nr_args, 6); i++)
1524 emit_ldx(prog, bytes_to_bpf_size(m->arg_size[i]),
1525 i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
1526 BPF_REG_FP,
1527 -(stack_size - i * 8));
1528 }
1529
1530 static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
1531 struct bpf_prog *p, int stack_size, bool mod_ret)
1532 {
1533 u8 *prog = *pprog;
1534 int cnt = 0;
1535
1536 if (p->aux->sleepable) {
1537 if (emit_call(&prog, __bpf_prog_enter_sleepable, prog))
1538 return -EINVAL;
1539 } else {
1540 if (emit_call(&prog, __bpf_prog_enter, prog))
1541 return -EINVAL;
1542 /* remember prog start time returned by __bpf_prog_enter */
1543 emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0);
1544 }
1545
1546 /* arg1: lea rdi, [rbp - stack_size] */
1547 EMIT4(0x48, 0x8D, 0x7D, -stack_size);
1548 /* arg2: progs[i]->insnsi for interpreter */
1549 if (!p->jited)
1550 emit_mov_imm64(&prog, BPF_REG_2,
1551 (long) p->insnsi >> 32,
1552 (u32) (long) p->insnsi);
1553 /* call JITed bpf program or interpreter */
1554 if (emit_call(&prog, p->bpf_func, prog))
1555 return -EINVAL;
1556
1557 /* BPF_TRAMP_MODIFY_RETURN trampolines can modify the return
1558 * of the previous call which is then passed on the stack to
1559 * the next BPF program.
1560 */
1561 if (mod_ret)
1562 emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
1563
1564 if (p->aux->sleepable) {
1565 if (emit_call(&prog, __bpf_prog_exit_sleepable, prog))
1566 return -EINVAL;
1567 } else {
1568 /* arg1: mov rdi, progs[i] */
1569 emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32,
1570 (u32) (long) p);
1571 /* arg2: mov rsi, rbx <- start time in nsec */
1572 emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6);
1573 if (emit_call(&prog, __bpf_prog_exit, prog))
1574 return -EINVAL;
1575 }
1576
1577 *pprog = prog;
1578 return 0;
1579 }
1580
1581 static void emit_nops(u8 **pprog, unsigned int len)
1582 {
1583 unsigned int i, noplen;
1584 u8 *prog = *pprog;
1585 int cnt = 0;
1586
1587 while (len > 0) {
1588 noplen = len;
1589
1590 if (noplen > ASM_NOP_MAX)
1591 noplen = ASM_NOP_MAX;
1592
1593 for (i = 0; i < noplen; i++)
1594 EMIT1(ideal_nops[noplen][i]);
1595 len -= noplen;
1596 }
1597
1598 *pprog = prog;
1599 }
1600
1601 static void emit_align(u8 **pprog, u32 align)
1602 {
1603 u8 *target, *prog = *pprog;
1604
1605 target = PTR_ALIGN(prog, align);
1606 if (target != prog)
1607 emit_nops(&prog, target - prog);
1608
1609 *pprog = prog;
1610 }
1611
1612 static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
1613 {
1614 u8 *prog = *pprog;
1615 int cnt = 0;
1616 s64 offset;
1617
1618 offset = func - (ip + 2 + 4);
1619 if (!is_simm32(offset)) {
1620 pr_err("Target %p is out of range\n", func);
1621 return -EINVAL;
1622 }
1623 EMIT2_off32(0x0F, jmp_cond + 0x10, offset);
1624 *pprog = prog;
1625 return 0;
1626 }
1627
1628 static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
1629 struct bpf_tramp_progs *tp, int stack_size)
1630 {
1631 int i;
1632 u8 *prog = *pprog;
1633
1634 for (i = 0; i < tp->nr_progs; i++) {
1635 if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size, false))
1636 return -EINVAL;
1637 }
1638 *pprog = prog;
1639 return 0;
1640 }
1641
1642 static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
1643 struct bpf_tramp_progs *tp, int stack_size,
1644 u8 **branches)
1645 {
1646 u8 *prog = *pprog;
1647 int i, cnt = 0;
1648
1649 /* The first fmod_ret program will receive a garbage return value.
1650 * Set this to 0 to avoid confusing the program.
1651 */
1652 emit_mov_imm32(&prog, false, BPF_REG_0, 0);
1653 emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
1654 for (i = 0; i < tp->nr_progs; i++) {
1655 if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size, true))
1656 return -EINVAL;
1657
1658 /* mod_ret prog stored return value into [rbp - 8]. Emit:
1659 * if (*(u64 *)(rbp - 8) != 0)
1660 * goto do_fexit;
1661 */
1662 /* cmp QWORD PTR [rbp - 0x8], 0x0 */
1663 EMIT4(0x48, 0x83, 0x7d, 0xf8); EMIT1(0x00);
1664
1665 /* Save the location of the branch and Generate 6 nops
1666 * (4 bytes for an offset and 2 bytes for the jump) These nops
1667 * are replaced with a conditional jump once do_fexit (i.e. the
1668 * start of the fexit invocation) is finalized.
1669 */
1670 branches[i] = prog;
1671 emit_nops(&prog, 4 + 2);
1672 }
1673
1674 *pprog = prog;
1675 return 0;
1676 }
1677
1678 /* Example:
1679 * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
1680 * its 'struct btf_func_model' will be nr_args=2
1681 * The assembly code when eth_type_trans is executing after trampoline:
1682 *
1683 * push rbp
1684 * mov rbp, rsp
1685 * sub rsp, 16 // space for skb and dev
1686 * push rbx // temp regs to pass start time
1687 * mov qword ptr [rbp - 16], rdi // save skb pointer to stack
1688 * mov qword ptr [rbp - 8], rsi // save dev pointer to stack
1689 * call __bpf_prog_enter // rcu_read_lock and preempt_disable
1690 * mov rbx, rax // remember start time in bpf stats are enabled
1691 * lea rdi, [rbp - 16] // R1==ctx of bpf prog
1692 * call addr_of_jited_FENTRY_prog
1693 * movabsq rdi, 64bit_addr_of_struct_bpf_prog // unused if bpf stats are off
1694 * mov rsi, rbx // prog start time
1695 * call __bpf_prog_exit // rcu_read_unlock, preempt_enable and stats math
1696 * mov rdi, qword ptr [rbp - 16] // restore skb pointer from stack
1697 * mov rsi, qword ptr [rbp - 8] // restore dev pointer from stack
1698 * pop rbx
1699 * leave
1700 * ret
1701 *
1702 * eth_type_trans has 5 byte nop at the beginning. These 5 bytes will be
1703 * replaced with 'call generated_bpf_trampoline'. When it returns
1704 * eth_type_trans will continue executing with original skb and dev pointers.
1705 *
1706 * The assembly code when eth_type_trans is called from trampoline:
1707 *
1708 * push rbp
1709 * mov rbp, rsp
1710 * sub rsp, 24 // space for skb, dev, return value
1711 * push rbx // temp regs to pass start time
1712 * mov qword ptr [rbp - 24], rdi // save skb pointer to stack
1713 * mov qword ptr [rbp - 16], rsi // save dev pointer to stack
1714 * call __bpf_prog_enter // rcu_read_lock and preempt_disable
1715 * mov rbx, rax // remember start time if bpf stats are enabled
1716 * lea rdi, [rbp - 24] // R1==ctx of bpf prog
1717 * call addr_of_jited_FENTRY_prog // bpf prog can access skb and dev
1718 * movabsq rdi, 64bit_addr_of_struct_bpf_prog // unused if bpf stats are off
1719 * mov rsi, rbx // prog start time
1720 * call __bpf_prog_exit // rcu_read_unlock, preempt_enable and stats math
1721 * mov rdi, qword ptr [rbp - 24] // restore skb pointer from stack
1722 * mov rsi, qword ptr [rbp - 16] // restore dev pointer from stack
1723 * call eth_type_trans+5 // execute body of eth_type_trans
1724 * mov qword ptr [rbp - 8], rax // save return value
1725 * call __bpf_prog_enter // rcu_read_lock and preempt_disable
1726 * mov rbx, rax // remember start time in bpf stats are enabled
1727 * lea rdi, [rbp - 24] // R1==ctx of bpf prog
1728 * call addr_of_jited_FEXIT_prog // bpf prog can access skb, dev, return value
1729 * movabsq rdi, 64bit_addr_of_struct_bpf_prog // unused if bpf stats are off
1730 * mov rsi, rbx // prog start time
1731 * call __bpf_prog_exit // rcu_read_unlock, preempt_enable and stats math
1732 * mov rax, qword ptr [rbp - 8] // restore eth_type_trans's return value
1733 * pop rbx
1734 * leave
1735 * add rsp, 8 // skip eth_type_trans's frame
1736 * ret // return to its caller
1737 */
1738 int arch_prepare_bpf_trampoline(void *image, void *image_end,
1739 const struct btf_func_model *m, u32 flags,
1740 struct bpf_tramp_progs *tprogs,
1741 void *orig_call)
1742 {
1743 int ret, i, cnt = 0, nr_args = m->nr_args;
1744 int stack_size = nr_args * 8;
1745 struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY];
1746 struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT];
1747 struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN];
1748 u8 **branches = NULL;
1749 u8 *prog;
1750
1751 /* x86-64 supports up to 6 arguments. 7+ can be added in the future */
1752 if (nr_args > 6)
1753 return -ENOTSUPP;
1754
1755 if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
1756 (flags & BPF_TRAMP_F_SKIP_FRAME))
1757 return -EINVAL;
1758
1759 if (flags & BPF_TRAMP_F_CALL_ORIG)
1760 stack_size += 8; /* room for return value of orig_call */
1761
1762 if (flags & BPF_TRAMP_F_SKIP_FRAME)
1763 /* skip patched call instruction and point orig_call to actual
1764 * body of the kernel function.
1765 */
1766 orig_call += X86_PATCH_SIZE;
1767
1768 prog = image;
1769
1770 EMIT1(0x55); /* push rbp */
1771 EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
1772 EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */
1773 EMIT1(0x53); /* push rbx */
1774
1775 save_regs(m, &prog, nr_args, stack_size);
1776
1777 if (fentry->nr_progs)
1778 if (invoke_bpf(m, &prog, fentry, stack_size))
1779 return -EINVAL;
1780
1781 if (fmod_ret->nr_progs) {
1782 branches = kcalloc(fmod_ret->nr_progs, sizeof(u8 *),
1783 GFP_KERNEL);
1784 if (!branches)
1785 return -ENOMEM;
1786
1787 if (invoke_bpf_mod_ret(m, &prog, fmod_ret, stack_size,
1788 branches)) {
1789 ret = -EINVAL;
1790 goto cleanup;
1791 }
1792 }
1793
1794 if (flags & BPF_TRAMP_F_CALL_ORIG) {
1795 if (fentry->nr_progs || fmod_ret->nr_progs)
1796 restore_regs(m, &prog, nr_args, stack_size);
1797
1798 /* call original function */
1799 if (emit_call(&prog, orig_call, prog)) {
1800 ret = -EINVAL;
1801 goto cleanup;
1802 }
1803 /* remember return value in a stack for bpf prog to access */
1804 emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
1805 }
1806
1807 if (fmod_ret->nr_progs) {
1808 /* From Intel 64 and IA-32 Architectures Optimization
1809 * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler
1810 * Coding Rule 11: All branch targets should be 16-byte
1811 * aligned.
1812 */
1813 emit_align(&prog, 16);
1814 /* Update the branches saved in invoke_bpf_mod_ret with the
1815 * aligned address of do_fexit.
1816 */
1817 for (i = 0; i < fmod_ret->nr_progs; i++)
1818 emit_cond_near_jump(&branches[i], prog, branches[i],
1819 X86_JNE);
1820 }
1821
1822 if (fexit->nr_progs)
1823 if (invoke_bpf(m, &prog, fexit, stack_size)) {
1824 ret = -EINVAL;
1825 goto cleanup;
1826 }
1827
1828 if (flags & BPF_TRAMP_F_RESTORE_REGS)
1829 restore_regs(m, &prog, nr_args, stack_size);
1830
1831 /* This needs to be done regardless. If there were fmod_ret programs,
1832 * the return value is only updated on the stack and still needs to be
1833 * restored to R0.
1834 */
1835 if (flags & BPF_TRAMP_F_CALL_ORIG)
1836 /* restore original return value back into RAX */
1837 emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);
1838
1839 EMIT1(0x5B); /* pop rbx */
1840 EMIT1(0xC9); /* leave */
1841 if (flags & BPF_TRAMP_F_SKIP_FRAME)
1842 /* skip our return address and return to parent */
1843 EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */
1844 EMIT1(0xC3); /* ret */
1845 /* Make sure the trampoline generation logic doesn't overflow */
1846 if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) {
1847 ret = -EFAULT;
1848 goto cleanup;
1849 }
1850 ret = prog - (u8 *)image;
1851
1852 cleanup:
1853 kfree(branches);
1854 return ret;
1855 }
1856
1857 static int emit_fallback_jump(u8 **pprog)
1858 {
1859 u8 *prog = *pprog;
1860 int err = 0;
1861
1862 #ifdef CONFIG_RETPOLINE
1863 /* Note that this assumes the the compiler uses external
1864 * thunks for indirect calls. Both clang and GCC use the same
1865 * naming convention for external thunks.
1866 */
1867 err = emit_jump(&prog, __x86_indirect_thunk_rdx, prog);
1868 #else
1869 int cnt = 0;
1870
1871 EMIT2(0xFF, 0xE2); /* jmp rdx */
1872 #endif
1873 *pprog = prog;
1874 return err;
1875 }
1876
1877 static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs)
1878 {
1879 u8 *jg_reloc, *prog = *pprog;
1880 int pivot, err, jg_bytes = 1, cnt = 0;
1881 s64 jg_offset;
1882
1883 if (a == b) {
1884 /* Leaf node of recursion, i.e. not a range of indices
1885 * anymore.
1886 */
1887 EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */
1888 if (!is_simm32(progs[a]))
1889 return -1;
1890 EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3),
1891 progs[a]);
1892 err = emit_cond_near_jump(&prog, /* je func */
1893 (void *)progs[a], prog,
1894 X86_JE);
1895 if (err)
1896 return err;
1897
1898 err = emit_fallback_jump(&prog); /* jmp thunk/indirect */
1899 if (err)
1900 return err;
1901
1902 *pprog = prog;
1903 return 0;
1904 }
1905
1906 /* Not a leaf node, so we pivot, and recursively descend into
1907 * the lower and upper ranges.
1908 */
1909 pivot = (b - a) / 2;
1910 EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */
1911 if (!is_simm32(progs[a + pivot]))
1912 return -1;
1913 EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), progs[a + pivot]);
1914
1915 if (pivot > 2) { /* jg upper_part */
1916 /* Require near jump. */
1917 jg_bytes = 4;
1918 EMIT2_off32(0x0F, X86_JG + 0x10, 0);
1919 } else {
1920 EMIT2(X86_JG, 0);
1921 }
1922 jg_reloc = prog;
1923
1924 err = emit_bpf_dispatcher(&prog, a, a + pivot, /* emit lower_part */
1925 progs);
1926 if (err)
1927 return err;
1928
1929 /* From Intel 64 and IA-32 Architectures Optimization
1930 * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler
1931 * Coding Rule 11: All branch targets should be 16-byte
1932 * aligned.
1933 */
1934 emit_align(&prog, 16);
1935 jg_offset = prog - jg_reloc;
1936 emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes);
1937
1938 err = emit_bpf_dispatcher(&prog, a + pivot + 1, /* emit upper_part */
1939 b, progs);
1940 if (err)
1941 return err;
1942
1943 *pprog = prog;
1944 return 0;
1945 }
1946
1947 static int cmp_ips(const void *a, const void *b)
1948 {
1949 const s64 *ipa = a;
1950 const s64 *ipb = b;
1951
1952 if (*ipa > *ipb)
1953 return 1;
1954 if (*ipa < *ipb)
1955 return -1;
1956 return 0;
1957 }
1958
1959 int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs)
1960 {
1961 u8 *prog = image;
1962
1963 sort(funcs, num_funcs, sizeof(funcs[0]), cmp_ips, NULL);
1964 return emit_bpf_dispatcher(&prog, 0, num_funcs - 1, funcs);
1965 }
1966
1967 struct x64_jit_data {
1968 struct bpf_binary_header *header;
1969 int *addrs;
1970 u8 *image;
1971 int proglen;
1972 struct jit_context ctx;
1973 };
1974
1975 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
1976 {
1977 struct bpf_binary_header *header = NULL;
1978 struct bpf_prog *tmp, *orig_prog = prog;
1979 struct x64_jit_data *jit_data;
1980 int proglen, oldproglen = 0;
1981 struct jit_context ctx = {};
1982 bool tmp_blinded = false;
1983 bool extra_pass = false;
1984 u8 *image = NULL;
1985 int *addrs;
1986 int pass;
1987 int i;
1988
1989 if (!prog->jit_requested)
1990 return orig_prog;
1991
1992 tmp = bpf_jit_blind_constants(prog);
1993 /*
1994 * If blinding was requested and we failed during blinding,
1995 * we must fall back to the interpreter.
1996 */
1997 if (IS_ERR(tmp))
1998 return orig_prog;
1999 if (tmp != prog) {
2000 tmp_blinded = true;
2001 prog = tmp;
2002 }
2003
2004 jit_data = prog->aux->jit_data;
2005 if (!jit_data) {
2006 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
2007 if (!jit_data) {
2008 prog = orig_prog;
2009 goto out;
2010 }
2011 prog->aux->jit_data = jit_data;
2012 }
2013 addrs = jit_data->addrs;
2014 if (addrs) {
2015 ctx = jit_data->ctx;
2016 oldproglen = jit_data->proglen;
2017 image = jit_data->image;
2018 header = jit_data->header;
2019 extra_pass = true;
2020 goto skip_init_addrs;
2021 }
2022 addrs = kmalloc_array(prog->len + 1, sizeof(*addrs), GFP_KERNEL);
2023 if (!addrs) {
2024 prog = orig_prog;
2025 goto out_addrs;
2026 }
2027
2028 /*
2029 * Before first pass, make a rough estimation of addrs[]
2030 * each BPF instruction is translated to less than 64 bytes
2031 */
2032 for (proglen = 0, i = 0; i <= prog->len; i++) {
2033 proglen += 64;
2034 addrs[i] = proglen;
2035 }
2036 ctx.cleanup_addr = proglen;
2037 skip_init_addrs:
2038
2039 /*
2040 * JITed image shrinks with every pass and the loop iterates
2041 * until the image stops shrinking. Very large BPF programs
2042 * may converge on the last pass. In such case do one more
2043 * pass to emit the final image.
2044 */
2045 for (pass = 0; pass < 20 || image; pass++) {
2046 proglen = do_jit(prog, addrs, image, oldproglen, &ctx);
2047 if (proglen <= 0) {
2048 out_image:
2049 image = NULL;
2050 if (header)
2051 bpf_jit_binary_free(header);
2052 prog = orig_prog;
2053 goto out_addrs;
2054 }
2055 if (image) {
2056 if (proglen != oldproglen) {
2057 pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
2058 proglen, oldproglen);
2059 goto out_image;
2060 }
2061 break;
2062 }
2063 if (proglen == oldproglen) {
2064 /*
2065 * The number of entries in extable is the number of BPF_LDX
2066 * insns that access kernel memory via "pointer to BTF type".
2067 * The verifier changed their opcode from LDX|MEM|size
2068 * to LDX|PROBE_MEM|size to make JITing easier.
2069 */
2070 u32 align = __alignof__(struct exception_table_entry);
2071 u32 extable_size = prog->aux->num_exentries *
2072 sizeof(struct exception_table_entry);
2073
2074 /* allocate module memory for x86 insns and extable */
2075 header = bpf_jit_binary_alloc(roundup(proglen, align) + extable_size,
2076 &image, align, jit_fill_hole);
2077 if (!header) {
2078 prog = orig_prog;
2079 goto out_addrs;
2080 }
2081 prog->aux->extable = (void *) image + roundup(proglen, align);
2082 }
2083 oldproglen = proglen;
2084 cond_resched();
2085 }
2086
2087 if (bpf_jit_enable > 1)
2088 bpf_jit_dump(prog->len, proglen, pass + 1, image);
2089
2090 if (image) {
2091 if (!prog->is_func || extra_pass) {
2092 bpf_tail_call_direct_fixup(prog);
2093 bpf_jit_binary_lock_ro(header);
2094 } else {
2095 jit_data->addrs = addrs;
2096 jit_data->ctx = ctx;
2097 jit_data->proglen = proglen;
2098 jit_data->image = image;
2099 jit_data->header = header;
2100 }
2101 prog->bpf_func = (void *)image;
2102 prog->jited = 1;
2103 prog->jited_len = proglen;
2104 } else {
2105 prog = orig_prog;
2106 }
2107
2108 if (!image || !prog->is_func || extra_pass) {
2109 if (image)
2110 bpf_prog_fill_jited_linfo(prog, addrs + 1);
2111 out_addrs:
2112 kfree(addrs);
2113 kfree(jit_data);
2114 prog->aux->jit_data = NULL;
2115 }
2116 out:
2117 if (tmp_blinded)
2118 bpf_jit_prog_release_other(prog, prog == orig_prog ?
2119 tmp : orig_prog);
2120 return prog;
2121 }
Linux with added FPC-III support