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1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * #pragma ident "@(#)fasttrap_isa.c 1.27 08/04/09 SMI"
29 */
30
31 #ifdef KERNEL
32 #ifndef _KERNEL
33 #define _KERNEL /* Solaris vs. Darwin */
34 #endif
35 #endif
36
37 #include <sys/fasttrap_isa.h>
38 #include <sys/fasttrap_impl.h>
39 #include <sys/dtrace.h>
40 #include <sys/dtrace_impl.h>
41 extern dtrace_id_t dtrace_probeid_error;
42
43 #include "fasttrap_regset.h"
44
45 #include <sys/dtrace_ptss.h>
46 #include <kern/debug.h>
47
48 #include <machine/pal_routines.h>
49
50 /* Solaris proc_t is the struct. Darwin's proc_t is a pointer to it. */
51 #define proc_t struct proc /* Steer clear of the Darwin typedef for proc_t */
52
53 /*
54 * Lossless User-Land Tracing on x86
55 * ---------------------------------
56 *
57 * The execution of most instructions is not dependent on the address; for
58 * these instructions it is sufficient to copy them into the user process's
59 * address space and execute them. To effectively single-step an instruction
60 * in user-land, we copy out the following sequence of instructions to scratch
61 * space in the user thread's ulwp_t structure.
62 *
63 * We then set the program counter (%eip or %rip) to point to this scratch
64 * space. Once execution resumes, the original instruction is executed and
65 * then control flow is redirected to what was originally the subsequent
66 * instruction. If the kernel attemps to deliver a signal while single-
67 * stepping, the signal is deferred and the program counter is moved into the
68 * second sequence of instructions. The second sequence ends in a trap into
69 * the kernel where the deferred signal is then properly handled and delivered.
70 *
71 * For instructions whose execute is position dependent, we perform simple
72 * emulation. These instructions are limited to control transfer
73 * instructions in 32-bit mode, but in 64-bit mode there's the added wrinkle
74 * of %rip-relative addressing that means that almost any instruction can be
75 * position dependent. For all the details on how we emulate generic
76 * instructions included %rip-relative instructions, see the code in
77 * fasttrap_pid_probe() below where we handle instructions of type
78 * FASTTRAP_T_COMMON (under the header: Generic Instruction Tracing).
79 */
80
81 #define FASTTRAP_MODRM_MOD(modrm) (((modrm) >> 6) & 0x3)
82 #define FASTTRAP_MODRM_REG(modrm) (((modrm) >> 3) & 0x7)
83 #define FASTTRAP_MODRM_RM(modrm) ((modrm) & 0x7)
84 #define FASTTRAP_MODRM(mod, reg, rm) (((mod) << 6) | ((reg) << 3) | (rm))
85
86 #define FASTTRAP_SIB_SCALE(sib) (((sib) >> 6) & 0x3)
87 #define FASTTRAP_SIB_INDEX(sib) (((sib) >> 3) & 0x7)
88 #define FASTTRAP_SIB_BASE(sib) ((sib) & 0x7)
89
90 #define FASTTRAP_REX_W(rex) (((rex) >> 3) & 1)
91 #define FASTTRAP_REX_R(rex) (((rex) >> 2) & 1)
92 #define FASTTRAP_REX_X(rex) (((rex) >> 1) & 1)
93 #define FASTTRAP_REX_B(rex) ((rex) & 1)
94 #define FASTTRAP_REX(w, r, x, b) \
95 (0x40 | ((w) << 3) | ((r) << 2) | ((x) << 1) | (b))
96
97 /*
98 * Single-byte op-codes.
99 */
100 #define FASTTRAP_PUSHL_EBP 0x55
101
102 #define FASTTRAP_JO 0x70
103 #define FASTTRAP_JNO 0x71
104 #define FASTTRAP_JB 0x72
105 #define FASTTRAP_JAE 0x73
106 #define FASTTRAP_JE 0x74
107 #define FASTTRAP_JNE 0x75
108 #define FASTTRAP_JBE 0x76
109 #define FASTTRAP_JA 0x77
110 #define FASTTRAP_JS 0x78
111 #define FASTTRAP_JNS 0x79
112 #define FASTTRAP_JP 0x7a
113 #define FASTTRAP_JNP 0x7b
114 #define FASTTRAP_JL 0x7c
115 #define FASTTRAP_JGE 0x7d
116 #define FASTTRAP_JLE 0x7e
117 #define FASTTRAP_JG 0x7f
118
119 #define FASTTRAP_NOP 0x90
120
121 #define FASTTRAP_MOV_EAX 0xb8
122 #define FASTTRAP_MOV_ECX 0xb9
123
124 #define FASTTRAP_RET16 0xc2
125 #define FASTTRAP_RET 0xc3
126
127 #define FASTTRAP_LOOPNZ 0xe0
128 #define FASTTRAP_LOOPZ 0xe1
129 #define FASTTRAP_LOOP 0xe2
130 #define FASTTRAP_JCXZ 0xe3
131
132 #define FASTTRAP_CALL 0xe8
133 #define FASTTRAP_JMP32 0xe9
134 #define FASTTRAP_JMP8 0xeb
135
136 #define FASTTRAP_INT3 0xcc
137 #define FASTTRAP_INT 0xcd
138 #define T_DTRACE_RET 0x7f
139
140 #define FASTTRAP_2_BYTE_OP 0x0f
141 #define FASTTRAP_GROUP5_OP 0xff
142
143 /*
144 * Two-byte op-codes (second byte only).
145 */
146 #define FASTTRAP_0F_JO 0x80
147 #define FASTTRAP_0F_JNO 0x81
148 #define FASTTRAP_0F_JB 0x82
149 #define FASTTRAP_0F_JAE 0x83
150 #define FASTTRAP_0F_JE 0x84
151 #define FASTTRAP_0F_JNE 0x85
152 #define FASTTRAP_0F_JBE 0x86
153 #define FASTTRAP_0F_JA 0x87
154 #define FASTTRAP_0F_JS 0x88
155 #define FASTTRAP_0F_JNS 0x89
156 #define FASTTRAP_0F_JP 0x8a
157 #define FASTTRAP_0F_JNP 0x8b
158 #define FASTTRAP_0F_JL 0x8c
159 #define FASTTRAP_0F_JGE 0x8d
160 #define FASTTRAP_0F_JLE 0x8e
161 #define FASTTRAP_0F_JG 0x8f
162
163 #define FASTTRAP_EFLAGS_OF 0x800
164 #define FASTTRAP_EFLAGS_DF 0x400
165 #define FASTTRAP_EFLAGS_SF 0x080
166 #define FASTTRAP_EFLAGS_ZF 0x040
167 #define FASTTRAP_EFLAGS_AF 0x010
168 #define FASTTRAP_EFLAGS_PF 0x004
169 #define FASTTRAP_EFLAGS_CF 0x001
170
171 /*
172 * Instruction prefixes.
173 */
174 #define FASTTRAP_PREFIX_OPERAND 0x66
175 #define FASTTRAP_PREFIX_ADDRESS 0x67
176 #define FASTTRAP_PREFIX_CS 0x2E
177 #define FASTTRAP_PREFIX_DS 0x3E
178 #define FASTTRAP_PREFIX_ES 0x26
179 #define FASTTRAP_PREFIX_FS 0x64
180 #define FASTTRAP_PREFIX_GS 0x65
181 #define FASTTRAP_PREFIX_SS 0x36
182 #define FASTTRAP_PREFIX_LOCK 0xF0
183 #define FASTTRAP_PREFIX_REP 0xF3
184 #define FASTTRAP_PREFIX_REPNE 0xF2
185
186 #define FASTTRAP_NOREG 0xff
187
188 /*
189 * Map between instruction register encodings and the kernel constants which
190 * correspond to indicies into struct regs.
191 */
192
193 /*
194 * APPLE NOTE: We are cheating here. The regmap is used to decode which register
195 * a given instruction is trying to reference. OS X does not have extended registers
196 * for 32 bit apps, but the *order* is the same. So for 32 bit state, we will return:
197 *
198 * REG_RAX -> EAX
199 * REG_RCX -> ECX
200 * ...
201 * REG_RDI -> EDI
202 *
203 * The fasttrap_getreg function knows how to make the correct transformation.
204 */
205 #if __sol64 || defined(__APPLE__)
206 static const uint8_t regmap[16] = {
207 REG_RAX, REG_RCX, REG_RDX, REG_RBX, REG_RSP, REG_RBP, REG_RSI, REG_RDI,
208 REG_R8, REG_R9, REG_R10, REG_R11, REG_R12, REG_R13, REG_R14, REG_R15,
209 };
210 #else
211 static const uint8_t regmap[8] = {
212 EAX, ECX, EDX, EBX, UESP, EBP, ESI, EDI
213 };
214 #endif
215
216 static user_addr_t fasttrap_getreg(x86_saved_state_t *, uint_t);
217
218 static uint64_t
219 fasttrap_anarg(x86_saved_state_t *regs, int function_entry, int argno)
220 {
221 uint64_t value;
222 int shift = function_entry ? 1 : 0;
223
224 x86_saved_state64_t *regs64;
225 x86_saved_state32_t *regs32;
226 unsigned int p_model;
227
228 if (is_saved_state64(regs)) {
229 regs64 = saved_state64(regs);
230 regs32 = NULL;
231 p_model = DATAMODEL_LP64;
232 } else {
233 regs64 = NULL;
234 regs32 = saved_state32(regs);
235 p_model = DATAMODEL_ILP32;
236 }
237
238 if (p_model == DATAMODEL_LP64) {
239 user_addr_t stack;
240
241 /*
242 * In 64-bit mode, the first six arguments are stored in
243 * registers.
244 */
245 if (argno < 6)
246 return ((&regs64->rdi)[argno]);
247
248 stack = regs64->isf.rsp + sizeof(uint64_t) * (argno - 6 + shift);
249 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
250 value = dtrace_fuword64(stack);
251 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR);
252 } else {
253 uint32_t *stack = (uint32_t *)(uintptr_t)(regs32->uesp);
254 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
255 value = dtrace_fuword32((user_addr_t)(unsigned long)&stack[argno + shift]);
256 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR);
257 }
258
259 return (value);
260 }
261
262 /*ARGSUSED*/
263 int
264 fasttrap_tracepoint_init(proc_t *p, fasttrap_tracepoint_t *tp, user_addr_t pc,
265 fasttrap_probe_type_t type)
266 {
267 #pragma unused(type)
268 uint8_t instr[FASTTRAP_MAX_INSTR_SIZE + 10];
269 size_t len = FASTTRAP_MAX_INSTR_SIZE;
270 size_t first = MIN(len, PAGE_SIZE - (pc & PAGE_MASK));
271 uint_t start = 0;
272 size_t size;
273 int rmindex;
274 uint8_t seg, rex = 0;
275 unsigned int p_model = (p->p_flag & P_LP64) ? DATAMODEL_LP64 : DATAMODEL_ILP32;
276
277 /*
278 * Read the instruction at the given address out of the process's
279 * address space. We don't have to worry about a debugger
280 * changing this instruction before we overwrite it with our trap
281 * instruction since P_PR_LOCK is set. Since instructions can span
282 * pages, we potentially read the instruction in two parts. If the
283 * second part fails, we just zero out that part of the instruction.
284 */
285 /*
286 * APPLE NOTE: Of course, we do not have a P_PR_LOCK, so this is racey...
287 */
288 if (uread(p, &instr[0], first, pc) != 0)
289 return (-1);
290 if (len > first &&
291 uread(p, &instr[first], len - first, pc + first) != 0) {
292 bzero(&instr[first], len - first);
293 len = first;
294 }
295
296 /*
297 * If the disassembly fails, then we have a malformed instruction.
298 */
299 if ((size = dtrace_instr_size_isa(instr, p_model, &rmindex)) <= 0)
300 return (-1);
301
302 /*
303 * Make sure the disassembler isn't completely broken.
304 */
305 ASSERT(-1 <= rmindex && rmindex < (int)size);
306
307 /*
308 * If the computed size is greater than the number of bytes read,
309 * then it was a malformed instruction possibly because it fell on a
310 * page boundary and the subsequent page was missing or because of
311 * some malicious user.
312 */
313 if (size > len)
314 return (-1);
315
316 tp->ftt_size = (uint8_t)size;
317 tp->ftt_segment = FASTTRAP_SEG_NONE;
318
319 /*
320 * Find the start of the instruction's opcode by processing any
321 * legacy prefixes.
322 */
323 for (;;) {
324 seg = 0;
325 switch (instr[start]) {
326 case FASTTRAP_PREFIX_SS:
327 seg++;
328 /*FALLTHRU*/
329 case FASTTRAP_PREFIX_GS:
330 seg++;
331 /*FALLTHRU*/
332 case FASTTRAP_PREFIX_FS:
333 seg++;
334 /*FALLTHRU*/
335 case FASTTRAP_PREFIX_ES:
336 seg++;
337 /*FALLTHRU*/
338 case FASTTRAP_PREFIX_DS:
339 seg++;
340 /*FALLTHRU*/
341 case FASTTRAP_PREFIX_CS:
342 seg++;
343 /*FALLTHRU*/
344 case FASTTRAP_PREFIX_OPERAND:
345 case FASTTRAP_PREFIX_ADDRESS:
346 case FASTTRAP_PREFIX_LOCK:
347 case FASTTRAP_PREFIX_REP:
348 case FASTTRAP_PREFIX_REPNE:
349 if (seg != 0) {
350 /*
351 * It's illegal for an instruction to specify
352 * two segment prefixes -- give up on this
353 * illegal instruction.
354 */
355 if (tp->ftt_segment != FASTTRAP_SEG_NONE)
356 return (-1);
357
358 tp->ftt_segment = seg;
359 }
360 start++;
361 continue;
362 }
363 break;
364 }
365
366 #if __sol64 || defined(__APPLE__)
367 /*
368 * Identify the REX prefix on 64-bit processes.
369 */
370 if (p_model == DATAMODEL_LP64 && (instr[start] & 0xf0) == 0x40)
371 rex = instr[start++];
372 #endif
373
374 /*
375 * Now that we're pretty sure that the instruction is okay, copy the
376 * valid part to the tracepoint.
377 */
378 bcopy(instr, tp->ftt_instr, FASTTRAP_MAX_INSTR_SIZE);
379
380 tp->ftt_type = FASTTRAP_T_COMMON;
381 if (instr[start] == FASTTRAP_2_BYTE_OP) {
382 switch (instr[start + 1]) {
383 case FASTTRAP_0F_JO:
384 case FASTTRAP_0F_JNO:
385 case FASTTRAP_0F_JB:
386 case FASTTRAP_0F_JAE:
387 case FASTTRAP_0F_JE:
388 case FASTTRAP_0F_JNE:
389 case FASTTRAP_0F_JBE:
390 case FASTTRAP_0F_JA:
391 case FASTTRAP_0F_JS:
392 case FASTTRAP_0F_JNS:
393 case FASTTRAP_0F_JP:
394 case FASTTRAP_0F_JNP:
395 case FASTTRAP_0F_JL:
396 case FASTTRAP_0F_JGE:
397 case FASTTRAP_0F_JLE:
398 case FASTTRAP_0F_JG:
399 tp->ftt_type = FASTTRAP_T_JCC;
400 tp->ftt_code = (instr[start + 1] & 0x0f) | FASTTRAP_JO;
401 tp->ftt_dest = pc + tp->ftt_size +
402 /* LINTED - alignment */
403 *(int32_t *)&instr[start + 2];
404 break;
405 }
406 } else if (instr[start] == FASTTRAP_GROUP5_OP) {
407 uint_t mod = FASTTRAP_MODRM_MOD(instr[start + 1]);
408 uint_t reg = FASTTRAP_MODRM_REG(instr[start + 1]);
409 uint_t rm = FASTTRAP_MODRM_RM(instr[start + 1]);
410
411 if (reg == 2 || reg == 4) {
412 uint_t i, sz;
413
414 if (reg == 2)
415 tp->ftt_type = FASTTRAP_T_CALL;
416 else
417 tp->ftt_type = FASTTRAP_T_JMP;
418
419 if (mod == 3)
420 tp->ftt_code = 2;
421 else
422 tp->ftt_code = 1;
423
424 ASSERT(p_model == DATAMODEL_LP64 || rex == 0);
425
426 /*
427 * See AMD x86-64 Architecture Programmer's Manual
428 * Volume 3, Section 1.2.7, Table 1-12, and
429 * Appendix A.3.1, Table A-15.
430 */
431 if (mod != 3 && rm == 4) {
432 uint8_t sib = instr[start + 2];
433 uint_t index = FASTTRAP_SIB_INDEX(sib);
434 uint_t base = FASTTRAP_SIB_BASE(sib);
435
436 tp->ftt_scale = FASTTRAP_SIB_SCALE(sib);
437
438 tp->ftt_index = (index == 4) ?
439 FASTTRAP_NOREG :
440 regmap[index | (FASTTRAP_REX_X(rex) << 3)];
441 tp->ftt_base = (mod == 0 && base == 5) ?
442 FASTTRAP_NOREG :
443 regmap[base | (FASTTRAP_REX_B(rex) << 3)];
444
445 i = 3;
446 sz = mod == 1 ? 1 : 4;
447 } else {
448 /*
449 * In 64-bit mode, mod == 0 and r/m == 5
450 * denotes %rip-relative addressing; in 32-bit
451 * mode, the base register isn't used. In both
452 * modes, there is a 32-bit operand.
453 */
454 if (mod == 0 && rm == 5) {
455 #if __sol64 || defined(__APPLE__)
456 if (p_model == DATAMODEL_LP64)
457 tp->ftt_base = REG_RIP;
458 else
459 #endif
460 tp->ftt_base = FASTTRAP_NOREG;
461 sz = 4;
462 } else {
463 uint8_t base = rm |
464 (FASTTRAP_REX_B(rex) << 3);
465
466 tp->ftt_base = regmap[base];
467 sz = mod == 1 ? 1 : mod == 2 ? 4 : 0;
468 }
469 tp->ftt_index = FASTTRAP_NOREG;
470 i = 2;
471 }
472
473 if (sz == 1) {
474 tp->ftt_dest = *(int8_t *)&instr[start + i];
475 } else if (sz == 4) {
476 /* LINTED - alignment */
477 tp->ftt_dest = *(int32_t *)&instr[start + i];
478 } else {
479 tp->ftt_dest = 0;
480 }
481 }
482 } else {
483 switch (instr[start]) {
484 case FASTTRAP_RET:
485 tp->ftt_type = FASTTRAP_T_RET;
486 break;
487
488 case FASTTRAP_RET16:
489 tp->ftt_type = FASTTRAP_T_RET16;
490 /* LINTED - alignment */
491 tp->ftt_dest = *(uint16_t *)&instr[start + 1];
492 break;
493
494 case FASTTRAP_JO:
495 case FASTTRAP_JNO:
496 case FASTTRAP_JB:
497 case FASTTRAP_JAE:
498 case FASTTRAP_JE:
499 case FASTTRAP_JNE:
500 case FASTTRAP_JBE:
501 case FASTTRAP_JA:
502 case FASTTRAP_JS:
503 case FASTTRAP_JNS:
504 case FASTTRAP_JP:
505 case FASTTRAP_JNP:
506 case FASTTRAP_JL:
507 case FASTTRAP_JGE:
508 case FASTTRAP_JLE:
509 case FASTTRAP_JG:
510 tp->ftt_type = FASTTRAP_T_JCC;
511 tp->ftt_code = instr[start];
512 tp->ftt_dest = pc + tp->ftt_size +
513 (int8_t)instr[start + 1];
514 break;
515
516 case FASTTRAP_LOOPNZ:
517 case FASTTRAP_LOOPZ:
518 case FASTTRAP_LOOP:
519 tp->ftt_type = FASTTRAP_T_LOOP;
520 tp->ftt_code = instr[start];
521 tp->ftt_dest = pc + tp->ftt_size +
522 (int8_t)instr[start + 1];
523 break;
524
525 case FASTTRAP_JCXZ:
526 tp->ftt_type = FASTTRAP_T_JCXZ;
527 tp->ftt_dest = pc + tp->ftt_size +
528 (int8_t)instr[start + 1];
529 break;
530
531 case FASTTRAP_CALL:
532 tp->ftt_type = FASTTRAP_T_CALL;
533 tp->ftt_dest = pc + tp->ftt_size +
534 /* LINTED - alignment */
535 *(int32_t *)&instr[start + 1];
536 tp->ftt_code = 0;
537 break;
538
539 case FASTTRAP_JMP32:
540 tp->ftt_type = FASTTRAP_T_JMP;
541 tp->ftt_dest = pc + tp->ftt_size +
542 /* LINTED - alignment */
543 *(int32_t *)&instr[start + 1];
544 break;
545 case FASTTRAP_JMP8:
546 tp->ftt_type = FASTTRAP_T_JMP;
547 tp->ftt_dest = pc + tp->ftt_size +
548 (int8_t)instr[start + 1];
549 break;
550
551 case FASTTRAP_PUSHL_EBP:
552 if (start == 0)
553 tp->ftt_type = FASTTRAP_T_PUSHL_EBP;
554 break;
555
556 case FASTTRAP_NOP:
557 #if __sol64 || defined(__APPLE__)
558 ASSERT(p_model == DATAMODEL_LP64 || rex == 0);
559
560 /*
561 * On sol64 we have to be careful not to confuse a nop
562 * (actually xchgl %eax, %eax) with an instruction using
563 * the same opcode, but that does something different
564 * (e.g. xchgl %r8d, %eax or xcghq %r8, %rax).
565 */
566 if (FASTTRAP_REX_B(rex) == 0)
567 #endif
568 tp->ftt_type = FASTTRAP_T_NOP;
569 break;
570
571 case FASTTRAP_INT3:
572 /*
573 * The pid provider shares the int3 trap with debugger
574 * breakpoints so we can't instrument them.
575 */
576 ASSERT(instr[start] == FASTTRAP_INSTR);
577 return (-1);
578
579 case FASTTRAP_INT:
580 /*
581 * Interrupts seem like they could be traced with
582 * no negative implications, but it's possible that
583 * a thread could be redirected by the trap handling
584 * code which would eventually return to the
585 * instruction after the interrupt. If the interrupt
586 * were in our scratch space, the subsequent
587 * instruction might be overwritten before we return.
588 * Accordingly we refuse to instrument any interrupt.
589 */
590 return (-1);
591 }
592 }
593
594 #if __sol64 || defined(__APPLE__)
595 if (p_model == DATAMODEL_LP64 && tp->ftt_type == FASTTRAP_T_COMMON) {
596 /*
597 * If the process is 64-bit and the instruction type is still
598 * FASTTRAP_T_COMMON -- meaning we're going to copy it out an
599 * execute it -- we need to watch for %rip-relative
600 * addressing mode. See the portion of fasttrap_pid_probe()
601 * below where we handle tracepoints with type
602 * FASTTRAP_T_COMMON for how we emulate instructions that
603 * employ %rip-relative addressing.
604 */
605 if (rmindex != -1) {
606 uint_t mod = FASTTRAP_MODRM_MOD(instr[rmindex]);
607 uint_t reg = FASTTRAP_MODRM_REG(instr[rmindex]);
608 uint_t rm = FASTTRAP_MODRM_RM(instr[rmindex]);
609
610 ASSERT(rmindex > (int)start);
611
612 if (mod == 0 && rm == 5) {
613 /*
614 * We need to be sure to avoid other
615 * registers used by this instruction. While
616 * the reg field may determine the op code
617 * rather than denoting a register, assuming
618 * that it denotes a register is always safe.
619 * We leave the REX field intact and use
620 * whatever value's there for simplicity.
621 */
622 if (reg != 0) {
623 tp->ftt_ripmode = FASTTRAP_RIP_1 |
624 (FASTTRAP_RIP_X *
625 FASTTRAP_REX_B(rex));
626 rm = 0;
627 } else {
628 tp->ftt_ripmode = FASTTRAP_RIP_2 |
629 (FASTTRAP_RIP_X *
630 FASTTRAP_REX_B(rex));
631 rm = 1;
632 }
633
634 tp->ftt_modrm = tp->ftt_instr[rmindex];
635 tp->ftt_instr[rmindex] =
636 FASTTRAP_MODRM(2, reg, rm);
637 }
638 }
639 }
640 #endif
641
642 return (0);
643 }
644
645 int
646 fasttrap_tracepoint_install(proc_t *p, fasttrap_tracepoint_t *tp)
647 {
648 fasttrap_instr_t instr = FASTTRAP_INSTR;
649
650 if (uwrite(p, &instr, 1, tp->ftt_pc) != 0)
651 return (-1);
652
653 return (0);
654 }
655
656 int
657 fasttrap_tracepoint_remove(proc_t *p, fasttrap_tracepoint_t *tp)
658 {
659 uint8_t instr;
660
661 /*
662 * Distinguish between read or write failures and a changed
663 * instruction.
664 */
665 if (uread(p, &instr, 1, tp->ftt_pc) != 0)
666 return (0);
667 if (instr != FASTTRAP_INSTR)
668 return (0);
669 if (uwrite(p, &tp->ftt_instr[0], 1, tp->ftt_pc) != 0)
670 return (-1);
671
672 return (0);
673 }
674
675 static void
676 fasttrap_return_common(x86_saved_state_t *regs, user_addr_t pc, pid_t pid,
677 user_addr_t new_pc)
678 {
679 x86_saved_state64_t *regs64;
680 x86_saved_state32_t *regs32;
681 unsigned int p_model;
682
683 dtrace_icookie_t cookie;
684
685 if (is_saved_state64(regs)) {
686 regs64 = saved_state64(regs);
687 regs32 = NULL;
688 p_model = DATAMODEL_LP64;
689 } else {
690 regs64 = NULL;
691 regs32 = saved_state32(regs);
692 p_model = DATAMODEL_ILP32;
693 }
694
695 fasttrap_tracepoint_t *tp;
696 fasttrap_bucket_t *bucket;
697 fasttrap_id_t *id;
698 lck_mtx_t *pid_mtx;
699
700 pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
701 lck_mtx_lock(pid_mtx);
702 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
703
704 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
705 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
706 tp->ftt_proc->ftpc_acount != 0)
707 break;
708 }
709
710 /*
711 * Don't sweat it if we can't find the tracepoint again; unlike
712 * when we're in fasttrap_pid_probe(), finding the tracepoint here
713 * is not essential to the correct execution of the process.
714 */
715 if (tp == NULL) {
716 lck_mtx_unlock(pid_mtx);
717 return;
718 }
719
720 for (id = tp->ftt_retids; id != NULL; id = id->fti_next) {
721 /*
722 * If there's a branch that could act as a return site, we
723 * need to trace it, and check here if the program counter is
724 * external to the function.
725 */
726 if (tp->ftt_type != FASTTRAP_T_RET &&
727 tp->ftt_type != FASTTRAP_T_RET16 &&
728 new_pc - id->fti_probe->ftp_faddr <
729 id->fti_probe->ftp_fsize)
730 continue;
731
732 /*
733 * Provide a hint to the stack trace functions to add the
734 * following pc to the top of the stack since it's missing
735 * on a return probe yet highly desirable for consistency.
736 */
737 cookie = dtrace_interrupt_disable();
738 cpu_core[CPU->cpu_id].cpuc_missing_tos = pc;
739 if (ISSET(current_proc()->p_lflag, P_LNOATTACH)) {
740 dtrace_probe(dtrace_probeid_error, 0 /* state */, id->fti_probe->ftp_id,
741 1 /* ndx */, -1 /* offset */, DTRACEFLT_UPRIV);
742 } else if (p_model == DATAMODEL_LP64) {
743 dtrace_probe(id->fti_probe->ftp_id,
744 pc - id->fti_probe->ftp_faddr,
745 regs64->rax, regs64->rdx, 0, 0);
746 } else {
747 dtrace_probe(id->fti_probe->ftp_id,
748 pc - id->fti_probe->ftp_faddr,
749 regs32->eax, regs32->edx, 0, 0);
750 }
751 /* remove the hint */
752 cpu_core[CPU->cpu_id].cpuc_missing_tos = 0;
753 dtrace_interrupt_enable(cookie);
754 }
755
756 lck_mtx_unlock(pid_mtx);
757 }
758
759 static void
760 fasttrap_sigsegv(proc_t *p, uthread_t t, user_addr_t addr)
761 {
762 proc_lock(p);
763
764 /* Set fault address and mark signal */
765 t->uu_code = addr;
766 t->uu_siglist |= sigmask(SIGSEGV);
767
768 /*
769 * XXX These two line may be redundant; if not, then we need
770 * XXX to potentially set the data address in the machine
771 * XXX specific thread state structure to indicate the address.
772 */
773 t->uu_exception = KERN_INVALID_ADDRESS; /* SIGSEGV */
774 t->uu_subcode = 0; /* XXX pad */
775
776 proc_unlock(p);
777
778 /* raise signal */
779 signal_setast(t->uu_context.vc_thread);
780 }
781
782 static void
783 fasttrap_usdt_args64(fasttrap_probe_t *probe, x86_saved_state64_t *regs64, int argc,
784 uint64_t *argv)
785 {
786 int i, x, cap = MIN(argc, probe->ftp_nargs);
787 user_addr_t stack = (user_addr_t)regs64->isf.rsp;
788
789 for (i = 0; i < cap; i++) {
790 x = probe->ftp_argmap[i];
791
792 if (x < 6) {
793 /* FIXME! This may be broken, needs testing */
794 argv[i] = (&regs64->rdi)[x];
795 } else {
796 fasttrap_fuword64_noerr(stack + (x * sizeof(uint64_t)), &argv[i]);
797 }
798 }
799
800 for (; i < argc; i++) {
801 argv[i] = 0;
802 }
803 }
804
805 static void
806 fasttrap_usdt_args32(fasttrap_probe_t *probe, x86_saved_state32_t *regs32, int argc,
807 uint32_t *argv)
808 {
809 int i, x, cap = MIN(argc, probe->ftp_nargs);
810 uint32_t *stack = (uint32_t *)(uintptr_t)(regs32->uesp);
811
812 for (i = 0; i < cap; i++) {
813 x = probe->ftp_argmap[i];
814
815 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[x], &argv[i]);
816 }
817
818 for (; i < argc; i++) {
819 argv[i] = 0;
820 }
821 }
822
823 /*
824 * FIXME!
825 */
826 static int
827 fasttrap_do_seg(fasttrap_tracepoint_t *tp, x86_saved_state_t *rp, user_addr_t *addr) // 64 bit
828 {
829 #pragma unused(tp, rp, addr)
830 printf("fasttrap_do_seg() called while unimplemented.\n");
831 #if 0
832 proc_t *p = curproc;
833 user_desc_t *desc;
834 uint16_t sel, ndx, type;
835 uintptr_t limit;
836
837 switch (tp->ftt_segment) {
838 case FASTTRAP_SEG_CS:
839 sel = rp->r_cs;
840 break;
841 case FASTTRAP_SEG_DS:
842 sel = rp->r_ds;
843 break;
844 case FASTTRAP_SEG_ES:
845 sel = rp->r_es;
846 break;
847 case FASTTRAP_SEG_FS:
848 sel = rp->r_fs;
849 break;
850 case FASTTRAP_SEG_GS:
851 sel = rp->r_gs;
852 break;
853 case FASTTRAP_SEG_SS:
854 sel = rp->r_ss;
855 break;
856 }
857
858 /*
859 * Make sure the given segment register specifies a user priority
860 * selector rather than a kernel selector.
861 */
862 if (!SELISUPL(sel))
863 return (-1);
864
865 ndx = SELTOIDX(sel);
866
867 /*
868 * Check the bounds and grab the descriptor out of the specified
869 * descriptor table.
870 */
871 if (SELISLDT(sel)) {
872 if (ndx > p->p_ldtlimit)
873 return (-1);
874
875 desc = p->p_ldt + ndx;
876
877 } else {
878 if (ndx >= NGDT)
879 return (-1);
880
881 desc = cpu_get_gdt() + ndx;
882 }
883
884 /*
885 * The descriptor must have user privilege level and it must be
886 * present in memory.
887 */
888 if (desc->usd_dpl != SEL_UPL || desc->usd_p != 1)
889 return (-1);
890
891 type = desc->usd_type;
892
893 /*
894 * If the S bit in the type field is not set, this descriptor can
895 * only be used in system context.
896 */
897 if ((type & 0x10) != 0x10)
898 return (-1);
899
900 limit = USEGD_GETLIMIT(desc) * (desc->usd_gran ? PAGESIZE : 1);
901
902 if (tp->ftt_segment == FASTTRAP_SEG_CS) {
903 /*
904 * The code/data bit and readable bit must both be set.
905 */
906 if ((type & 0xa) != 0xa)
907 return (-1);
908
909 if (*addr > limit)
910 return (-1);
911 } else {
912 /*
913 * The code/data bit must be clear.
914 */
915 if ((type & 0x8) != 0)
916 return (-1);
917
918 /*
919 * If the expand-down bit is clear, we just check the limit as
920 * it would naturally be applied. Otherwise, we need to check
921 * that the address is the range [limit + 1 .. 0xffff] or
922 * [limit + 1 ... 0xffffffff] depending on if the default
923 * operand size bit is set.
924 */
925 if ((type & 0x4) == 0) {
926 if (*addr > limit)
927 return (-1);
928 } else if (desc->usd_def32) {
929 if (*addr < limit + 1 || 0xffff < *addr)
930 return (-1);
931 } else {
932 if (*addr < limit + 1 || 0xffffffff < *addr)
933 return (-1);
934 }
935 }
936
937 *addr += USEGD_GETBASE(desc);
938 #endif /* 0 */
939 return (0);
940 }
941
942 /*
943 * Due to variances between Solaris and xnu, I have split this into a 32 bit and 64 bit
944 * code path. It still takes an x86_saved_state_t* argument, because it must sometimes
945 * call other methods that require a x86_saved_state_t.
946 *
947 * NOTE!!!!
948 *
949 * Any changes made to this method must be echo'd in fasttrap_pid_probe64!
950 *
951 */
952 static int
953 fasttrap_pid_probe32(x86_saved_state_t *regs)
954 {
955 ASSERT(is_saved_state32(regs));
956
957 x86_saved_state32_t *regs32 = saved_state32(regs);
958 user_addr_t pc = regs32->eip - 1;
959 proc_t *p = current_proc();
960 user_addr_t new_pc = 0;
961 fasttrap_bucket_t *bucket;
962 lck_mtx_t *pid_mtx;
963 fasttrap_tracepoint_t *tp, tp_local;
964 pid_t pid;
965 dtrace_icookie_t cookie;
966 uint_t is_enabled = 0;
967
968 uthread_t uthread = (uthread_t)get_bsdthread_info(current_thread());
969
970 /*
971 * It's possible that a user (in a veritable orgy of bad planning)
972 * could redirect this thread's flow of control before it reached the
973 * return probe fasttrap. In this case we need to kill the process
974 * since it's in a unrecoverable state.
975 */
976 if (uthread->t_dtrace_step) {
977 ASSERT(uthread->t_dtrace_on);
978 fasttrap_sigtrap(p, uthread, pc);
979 return (0);
980 }
981
982 /*
983 * Clear all user tracing flags.
984 */
985 uthread->t_dtrace_ft = 0;
986 uthread->t_dtrace_pc = 0;
987 uthread->t_dtrace_npc = 0;
988 uthread->t_dtrace_scrpc = 0;
989 uthread->t_dtrace_astpc = 0;
990
991 /*
992 * Treat a child created by a call to vfork(2) as if it were its
993 * parent. We know that there's only one thread of control in such a
994 * process: this one.
995 */
996 /*
997 * APPLE NOTE: Terry says: "You need to hold the process locks (currently: kernel funnel) for this traversal"
998 * FIXME: How do we assert this?
999 */
1000 while (p->p_lflag & P_LINVFORK)
1001 p = p->p_pptr;
1002
1003 pid = p->p_pid;
1004 pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
1005 lck_mtx_lock(pid_mtx);
1006 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
1007
1008 /*
1009 * Lookup the tracepoint that the process just hit.
1010 */
1011 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
1012 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
1013 tp->ftt_proc->ftpc_acount != 0)
1014 break;
1015 }
1016
1017 /*
1018 * If we couldn't find a matching tracepoint, either a tracepoint has
1019 * been inserted without using the pid<pid> ioctl interface (see
1020 * fasttrap_ioctl), or somehow we have mislaid this tracepoint.
1021 */
1022 if (tp == NULL) {
1023 lck_mtx_unlock(pid_mtx);
1024 return (-1);
1025 }
1026
1027 /*
1028 * Set the program counter to the address of the traced instruction
1029 * so that it looks right in ustack() output.
1030 */
1031 regs32->eip = pc;
1032
1033 if (tp->ftt_ids != NULL) {
1034 fasttrap_id_t *id;
1035
1036 uint32_t s0, s1, s2, s3, s4, s5;
1037 uint32_t *stack = (uint32_t *)(uintptr_t)(regs32->uesp);
1038
1039 /*
1040 * In 32-bit mode, all arguments are passed on the
1041 * stack. If this is a function entry probe, we need
1042 * to skip the first entry on the stack as it
1043 * represents the return address rather than a
1044 * parameter to the function.
1045 */
1046 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[0], &s0);
1047 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[1], &s1);
1048 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[2], &s2);
1049 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[3], &s3);
1050 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[4], &s4);
1051 fasttrap_fuword32_noerr((user_addr_t)(unsigned long)&stack[5], &s5);
1052
1053 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) {
1054 fasttrap_probe_t *probe = id->fti_probe;
1055
1056 if (ISSET(current_proc()->p_lflag, P_LNOATTACH)) {
1057 dtrace_probe(dtrace_probeid_error, 0 /* state */, probe->ftp_id,
1058 1 /* ndx */, -1 /* offset */, DTRACEFLT_UPRIV);
1059 } else if (id->fti_ptype == DTFTP_ENTRY) {
1060 /*
1061 * We note that this was an entry
1062 * probe to help ustack() find the
1063 * first caller.
1064 */
1065 cookie = dtrace_interrupt_disable();
1066 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY);
1067 dtrace_probe(probe->ftp_id, s1, s2,
1068 s3, s4, s5);
1069 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY);
1070 dtrace_interrupt_enable(cookie);
1071 } else if (id->fti_ptype == DTFTP_IS_ENABLED) {
1072 /*
1073 * Note that in this case, we don't
1074 * call dtrace_probe() since it's only
1075 * an artificial probe meant to change
1076 * the flow of control so that it
1077 * encounters the true probe.
1078 */
1079 is_enabled = 1;
1080 } else if (probe->ftp_argmap == NULL) {
1081 dtrace_probe(probe->ftp_id, s0, s1,
1082 s2, s3, s4);
1083 } else {
1084 uint32_t t[5];
1085
1086 fasttrap_usdt_args32(probe, regs32,
1087 sizeof (t) / sizeof (t[0]), t);
1088
1089 dtrace_probe(probe->ftp_id, t[0], t[1],
1090 t[2], t[3], t[4]);
1091 }
1092
1093 /* APPLE NOTE: Oneshot probes get one and only one chance... */
1094 if (probe->ftp_prov->ftp_provider_type == DTFTP_PROVIDER_ONESHOT) {
1095 fasttrap_tracepoint_remove(p, tp);
1096 }
1097 }
1098 }
1099
1100 /*
1101 * We're about to do a bunch of work so we cache a local copy of
1102 * the tracepoint to emulate the instruction, and then find the
1103 * tracepoint again later if we need to light up any return probes.
1104 */
1105 tp_local = *tp;
1106 lck_mtx_unlock(pid_mtx);
1107 tp = &tp_local;
1108
1109 /*
1110 * Set the program counter to appear as though the traced instruction
1111 * had completely executed. This ensures that fasttrap_getreg() will
1112 * report the expected value for REG_RIP.
1113 */
1114 regs32->eip = pc + tp->ftt_size;
1115
1116 /*
1117 * If there's an is-enabled probe connected to this tracepoint it
1118 * means that there was a 'xorl %eax, %eax' or 'xorq %rax, %rax'
1119 * instruction that was placed there by DTrace when the binary was
1120 * linked. As this probe is, in fact, enabled, we need to stuff 1
1121 * into %eax or %rax. Accordingly, we can bypass all the instruction
1122 * emulation logic since we know the inevitable result. It's possible
1123 * that a user could construct a scenario where the 'is-enabled'
1124 * probe was on some other instruction, but that would be a rather
1125 * exotic way to shoot oneself in the foot.
1126 */
1127 if (is_enabled) {
1128 regs32->eax = 1;
1129 new_pc = regs32->eip;
1130 goto done;
1131 }
1132
1133 /*
1134 * We emulate certain types of instructions to ensure correctness
1135 * (in the case of position dependent instructions) or optimize
1136 * common cases. The rest we have the thread execute back in user-
1137 * land.
1138 */
1139 switch (tp->ftt_type) {
1140 case FASTTRAP_T_RET:
1141 case FASTTRAP_T_RET16:
1142 {
1143 user_addr_t dst;
1144 user_addr_t addr;
1145 int ret;
1146
1147 /*
1148 * We have to emulate _every_ facet of the behavior of a ret
1149 * instruction including what happens if the load from %esp
1150 * fails; in that case, we send a SIGSEGV.
1151 */
1152 uint32_t dst32;
1153 ret = fasttrap_fuword32((user_addr_t)regs32->uesp, &dst32);
1154 dst = dst32;
1155 addr = regs32->uesp + sizeof (uint32_t);
1156
1157 if (ret == -1) {
1158 fasttrap_sigsegv(p, uthread, (user_addr_t)regs32->uesp);
1159 new_pc = pc;
1160 break;
1161 }
1162
1163 if (tp->ftt_type == FASTTRAP_T_RET16)
1164 addr += tp->ftt_dest;
1165
1166 regs32->uesp = addr;
1167 new_pc = dst;
1168 break;
1169 }
1170
1171 case FASTTRAP_T_JCC:
1172 {
1173 uint_t taken;
1174
1175 switch (tp->ftt_code) {
1176 case FASTTRAP_JO:
1177 taken = (regs32->efl & FASTTRAP_EFLAGS_OF) != 0;
1178 break;
1179 case FASTTRAP_JNO:
1180 taken = (regs32->efl & FASTTRAP_EFLAGS_OF) == 0;
1181 break;
1182 case FASTTRAP_JB:
1183 taken = (regs32->efl & FASTTRAP_EFLAGS_CF) != 0;
1184 break;
1185 case FASTTRAP_JAE:
1186 taken = (regs32->efl & FASTTRAP_EFLAGS_CF) == 0;
1187 break;
1188 case FASTTRAP_JE:
1189 taken = (regs32->efl & FASTTRAP_EFLAGS_ZF) != 0;
1190 break;
1191 case FASTTRAP_JNE:
1192 taken = (regs32->efl & FASTTRAP_EFLAGS_ZF) == 0;
1193 break;
1194 case FASTTRAP_JBE:
1195 taken = (regs32->efl & FASTTRAP_EFLAGS_CF) != 0 ||
1196 (regs32->efl & FASTTRAP_EFLAGS_ZF) != 0;
1197 break;
1198 case FASTTRAP_JA:
1199 taken = (regs32->efl & FASTTRAP_EFLAGS_CF) == 0 &&
1200 (regs32->efl & FASTTRAP_EFLAGS_ZF) == 0;
1201 break;
1202 case FASTTRAP_JS:
1203 taken = (regs32->efl & FASTTRAP_EFLAGS_SF) != 0;
1204 break;
1205 case FASTTRAP_JNS:
1206 taken = (regs32->efl & FASTTRAP_EFLAGS_SF) == 0;
1207 break;
1208 case FASTTRAP_JP:
1209 taken = (regs32->efl & FASTTRAP_EFLAGS_PF) != 0;
1210 break;
1211 case FASTTRAP_JNP:
1212 taken = (regs32->efl & FASTTRAP_EFLAGS_PF) == 0;
1213 break;
1214 case FASTTRAP_JL:
1215 taken = ((regs32->efl & FASTTRAP_EFLAGS_SF) == 0) !=
1216 ((regs32->efl & FASTTRAP_EFLAGS_OF) == 0);
1217 break;
1218 case FASTTRAP_JGE:
1219 taken = ((regs32->efl & FASTTRAP_EFLAGS_SF) == 0) ==
1220 ((regs32->efl & FASTTRAP_EFLAGS_OF) == 0);
1221 break;
1222 case FASTTRAP_JLE:
1223 taken = (regs32->efl & FASTTRAP_EFLAGS_ZF) != 0 ||
1224 ((regs32->efl & FASTTRAP_EFLAGS_SF) == 0) !=
1225 ((regs32->efl & FASTTRAP_EFLAGS_OF) == 0);
1226 break;
1227 case FASTTRAP_JG:
1228 taken = (regs32->efl & FASTTRAP_EFLAGS_ZF) == 0 &&
1229 ((regs32->efl & FASTTRAP_EFLAGS_SF) == 0) ==
1230 ((regs32->efl & FASTTRAP_EFLAGS_OF) == 0);
1231 break;
1232 default:
1233 taken = FALSE;
1234 }
1235
1236 if (taken)
1237 new_pc = tp->ftt_dest;
1238 else
1239 new_pc = pc + tp->ftt_size;
1240 break;
1241 }
1242
1243 case FASTTRAP_T_LOOP:
1244 {
1245 uint_t taken;
1246 greg_t cx = regs32->ecx--;
1247
1248 switch (tp->ftt_code) {
1249 case FASTTRAP_LOOPNZ:
1250 taken = (regs32->efl & FASTTRAP_EFLAGS_ZF) == 0 &&
1251 cx != 0;
1252 break;
1253 case FASTTRAP_LOOPZ:
1254 taken = (regs32->efl & FASTTRAP_EFLAGS_ZF) != 0 &&
1255 cx != 0;
1256 break;
1257 case FASTTRAP_LOOP:
1258 taken = (cx != 0);
1259 break;
1260 default:
1261 taken = FALSE;
1262 }
1263
1264 if (taken)
1265 new_pc = tp->ftt_dest;
1266 else
1267 new_pc = pc + tp->ftt_size;
1268 break;
1269 }
1270
1271 case FASTTRAP_T_JCXZ:
1272 {
1273 greg_t cx = regs32->ecx;
1274
1275 if (cx == 0)
1276 new_pc = tp->ftt_dest;
1277 else
1278 new_pc = pc + tp->ftt_size;
1279 break;
1280 }
1281
1282 case FASTTRAP_T_PUSHL_EBP:
1283 {
1284 user_addr_t addr = regs32->uesp - sizeof (uint32_t);
1285 int ret = fasttrap_suword32(addr, (uint32_t)regs32->ebp);
1286
1287 if (ret == -1) {
1288 fasttrap_sigsegv(p, uthread, addr);
1289 new_pc = pc;
1290 break;
1291 }
1292
1293 regs32->uesp = addr;
1294 new_pc = pc + tp->ftt_size;
1295 break;
1296 }
1297
1298 case FASTTRAP_T_NOP:
1299 new_pc = pc + tp->ftt_size;
1300 break;
1301
1302 case FASTTRAP_T_JMP:
1303 case FASTTRAP_T_CALL:
1304 if (tp->ftt_code == 0) {
1305 new_pc = tp->ftt_dest;
1306 } else {
1307 user_addr_t /* value ,*/ addr = tp->ftt_dest;
1308
1309 if (tp->ftt_base != FASTTRAP_NOREG)
1310 addr += fasttrap_getreg(regs, tp->ftt_base);
1311 if (tp->ftt_index != FASTTRAP_NOREG)
1312 addr += fasttrap_getreg(regs, tp->ftt_index) <<
1313 tp->ftt_scale;
1314
1315 if (tp->ftt_code == 1) {
1316 /*
1317 * If there's a segment prefix for this
1318 * instruction, we'll need to check permissions
1319 * and bounds on the given selector, and adjust
1320 * the address accordingly.
1321 */
1322 if (tp->ftt_segment != FASTTRAP_SEG_NONE &&
1323 fasttrap_do_seg(tp, regs, &addr) != 0) {
1324 fasttrap_sigsegv(p, uthread, addr);
1325 new_pc = pc;
1326 break;
1327 }
1328
1329 uint32_t value32;
1330 addr = (user_addr_t)(uint32_t)addr;
1331 if (fasttrap_fuword32(addr, &value32) == -1) {
1332 fasttrap_sigsegv(p, uthread, addr);
1333 new_pc = pc;
1334 break;
1335 }
1336 new_pc = value32;
1337 } else {
1338 new_pc = addr;
1339 }
1340 }
1341
1342 /*
1343 * If this is a call instruction, we need to push the return
1344 * address onto the stack. If this fails, we send the process
1345 * a SIGSEGV and reset the pc to emulate what would happen if
1346 * this instruction weren't traced.
1347 */
1348 if (tp->ftt_type == FASTTRAP_T_CALL) {
1349 user_addr_t addr = regs32->uesp - sizeof (uint32_t);
1350 int ret = fasttrap_suword32(addr, (uint32_t)(pc + tp->ftt_size));
1351
1352 if (ret == -1) {
1353 fasttrap_sigsegv(p, uthread, addr);
1354 new_pc = pc;
1355 break;
1356 }
1357
1358 regs32->uesp = addr;
1359 }
1360 break;
1361
1362 case FASTTRAP_T_COMMON:
1363 {
1364 user_addr_t addr;
1365 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 7];
1366 uint_t i = 0;
1367
1368 /*
1369 * Generic Instruction Tracing
1370 * ---------------------------
1371 *
1372 * This is the layout of the scratch space in the user-land
1373 * thread structure for our generated instructions.
1374 *
1375 * 32-bit mode bytes
1376 * ------------------------ -----
1377 * a: <original instruction> <= 15
1378 * jmp <pc + tp->ftt_size> 5
1379 * b: <original instrction> <= 15
1380 * int T_DTRACE_RET 2
1381 * -----
1382 * <= 37
1383 *
1384 * 64-bit mode bytes
1385 * ------------------------ -----
1386 * a: <original instruction> <= 15
1387 * jmp 0(%rip) 6
1388 * <pc + tp->ftt_size> 8
1389 * b: <original instruction> <= 15
1390 * int T_DTRACE_RET 2
1391 * -----
1392 * <= 46
1393 *
1394 * The %pc is set to a, and curthread->t_dtrace_astpc is set
1395 * to b. If we encounter a signal on the way out of the
1396 * kernel, trap() will set %pc to curthread->t_dtrace_astpc
1397 * so that we execute the original instruction and re-enter
1398 * the kernel rather than redirecting to the next instruction.
1399 *
1400 * If there are return probes (so we know that we're going to
1401 * need to reenter the kernel after executing the original
1402 * instruction), the scratch space will just contain the
1403 * original instruction followed by an interrupt -- the same
1404 * data as at b.
1405 */
1406
1407 addr = uthread->t_dtrace_scratch->addr;
1408
1409 if (addr == 0LL) {
1410 fasttrap_sigtrap(p, uthread, pc); // Should be killing target proc
1411 new_pc = pc;
1412 break;
1413 }
1414
1415 ASSERT(tp->ftt_size < FASTTRAP_MAX_INSTR_SIZE);
1416
1417 uthread->t_dtrace_scrpc = addr;
1418 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
1419 i += tp->ftt_size;
1420
1421 /*
1422 * Set up the jmp to the next instruction; note that
1423 * the size of the traced instruction cancels out.
1424 */
1425 scratch[i++] = FASTTRAP_JMP32;
1426 /* LINTED - alignment */
1427 *(uint32_t *)&scratch[i] = pc - addr - 5;
1428 i += sizeof (uint32_t);
1429
1430 uthread->t_dtrace_astpc = addr + i;
1431 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
1432 i += tp->ftt_size;
1433 scratch[i++] = FASTTRAP_INT;
1434 scratch[i++] = T_DTRACE_RET;
1435
1436 ASSERT(i <= sizeof (scratch));
1437
1438 if (fasttrap_copyout(scratch, addr, i)) {
1439 fasttrap_sigtrap(p, uthread, pc);
1440 new_pc = pc;
1441 break;
1442 }
1443
1444 if (tp->ftt_retids != NULL) {
1445 uthread->t_dtrace_step = 1;
1446 uthread->t_dtrace_ret = 1;
1447 new_pc = uthread->t_dtrace_astpc;
1448 } else {
1449 new_pc = uthread->t_dtrace_scrpc;
1450 }
1451
1452 uthread->t_dtrace_pc = pc;
1453 uthread->t_dtrace_npc = pc + tp->ftt_size;
1454 uthread->t_dtrace_on = 1;
1455 break;
1456 }
1457
1458 default:
1459 panic("fasttrap: mishandled an instruction");
1460 }
1461
1462 done:
1463 /*
1464 * APPLE NOTE:
1465 *
1466 * We're setting this earlier than Solaris does, to get a "correct"
1467 * ustack() output. In the Sun code, a() -> b() -> c() -> d() is
1468 * reported at: d, b, a. The new way gives c, b, a, which is closer
1469 * to correct, as the return instruction has already exectued.
1470 */
1471 regs32->eip = new_pc;
1472
1473 /*
1474 * If there were no return probes when we first found the tracepoint,
1475 * we should feel no obligation to honor any return probes that were
1476 * subsequently enabled -- they'll just have to wait until the next
1477 * time around.
1478 */
1479 if (tp->ftt_retids != NULL) {
1480 /*
1481 * We need to wait until the results of the instruction are
1482 * apparent before invoking any return probes. If this
1483 * instruction was emulated we can just call
1484 * fasttrap_return_common(); if it needs to be executed, we
1485 * need to wait until the user thread returns to the kernel.
1486 */
1487 if (tp->ftt_type != FASTTRAP_T_COMMON) {
1488 fasttrap_return_common(regs, pc, pid, new_pc);
1489 } else {
1490 ASSERT(uthread->t_dtrace_ret != 0);
1491 ASSERT(uthread->t_dtrace_pc == pc);
1492 ASSERT(uthread->t_dtrace_scrpc != 0);
1493 ASSERT(new_pc == uthread->t_dtrace_astpc);
1494 }
1495 }
1496
1497 return (0);
1498 }
1499
1500 /*
1501 * Due to variances between Solaris and xnu, I have split this into a 32 bit and 64 bit
1502 * code path. It still takes an x86_saved_state_t* argument, because it must sometimes
1503 * call other methods that require a x86_saved_state_t.
1504 *
1505 * NOTE!!!!
1506 *
1507 * Any changes made to this method must be echo'd in fasttrap_pid_probe32!
1508 *
1509 */
1510 static int
1511 fasttrap_pid_probe64(x86_saved_state_t *regs)
1512 {
1513 ASSERT(is_saved_state64(regs));
1514
1515 x86_saved_state64_t *regs64 = saved_state64(regs);
1516 user_addr_t pc = regs64->isf.rip - 1;
1517 proc_t *p = current_proc();
1518 user_addr_t new_pc = 0;
1519 fasttrap_bucket_t *bucket;
1520 lck_mtx_t *pid_mtx;
1521 fasttrap_tracepoint_t *tp, tp_local;
1522 pid_t pid;
1523 dtrace_icookie_t cookie;
1524 uint_t is_enabled = 0;
1525
1526 uthread_t uthread = (uthread_t)get_bsdthread_info(current_thread());
1527
1528 /*
1529 * It's possible that a user (in a veritable orgy of bad planning)
1530 * could redirect this thread's flow of control before it reached the
1531 * return probe fasttrap. In this case we need to kill the process
1532 * since it's in a unrecoverable state.
1533 */
1534 if (uthread->t_dtrace_step) {
1535 ASSERT(uthread->t_dtrace_on);
1536 fasttrap_sigtrap(p, uthread, pc);
1537 return (0);
1538 }
1539
1540 /*
1541 * Clear all user tracing flags.
1542 */
1543 uthread->t_dtrace_ft = 0;
1544 uthread->t_dtrace_pc = 0;
1545 uthread->t_dtrace_npc = 0;
1546 uthread->t_dtrace_scrpc = 0;
1547 uthread->t_dtrace_astpc = 0;
1548 uthread->t_dtrace_regv = 0;
1549
1550 /*
1551 * Treat a child created by a call to vfork(2) as if it were its
1552 * parent. We know that there's only one thread of control in such a
1553 * process: this one.
1554 */
1555 /*
1556 * APPLE NOTE: Terry says: "You need to hold the process locks (currently: kernel funnel) for this traversal"
1557 * FIXME: How do we assert this?
1558 */
1559 while (p->p_lflag & P_LINVFORK)
1560 p = p->p_pptr;
1561
1562 pid = p->p_pid;
1563 pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
1564 lck_mtx_lock(pid_mtx);
1565 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
1566
1567 /*
1568 * Lookup the tracepoint that the process just hit.
1569 */
1570 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
1571 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
1572 tp->ftt_proc->ftpc_acount != 0)
1573 break;
1574 }
1575
1576 /*
1577 * If we couldn't find a matching tracepoint, either a tracepoint has
1578 * been inserted without using the pid<pid> ioctl interface (see
1579 * fasttrap_ioctl), or somehow we have mislaid this tracepoint.
1580 */
1581 if (tp == NULL) {
1582 lck_mtx_unlock(pid_mtx);
1583 return (-1);
1584 }
1585
1586 /*
1587 * Set the program counter to the address of the traced instruction
1588 * so that it looks right in ustack() output.
1589 */
1590 regs64->isf.rip = pc;
1591
1592 if (tp->ftt_ids != NULL) {
1593 fasttrap_id_t *id;
1594
1595 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) {
1596 fasttrap_probe_t *probe = id->fti_probe;
1597
1598 if (ISSET(current_proc()->p_lflag, P_LNOATTACH)) {
1599 dtrace_probe(dtrace_probeid_error, 0 /* state */, probe->ftp_id,
1600 1 /* ndx */, -1 /* offset */, DTRACEFLT_UPRIV);
1601 } else if (id->fti_ptype == DTFTP_ENTRY) {
1602 /*
1603 * We note that this was an entry
1604 * probe to help ustack() find the
1605 * first caller.
1606 */
1607 cookie = dtrace_interrupt_disable();
1608 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY);
1609 dtrace_probe(probe->ftp_id, regs64->rdi,
1610 regs64->rsi, regs64->rdx, regs64->rcx,
1611 regs64->r8);
1612 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY);
1613 dtrace_interrupt_enable(cookie);
1614 } else if (id->fti_ptype == DTFTP_IS_ENABLED) {
1615 /*
1616 * Note that in this case, we don't
1617 * call dtrace_probe() since it's only
1618 * an artificial probe meant to change
1619 * the flow of control so that it
1620 * encounters the true probe.
1621 */
1622 is_enabled = 1;
1623 } else if (probe->ftp_argmap == NULL) {
1624 dtrace_probe(probe->ftp_id, regs64->rdi,
1625 regs64->rsi, regs64->rdx, regs64->rcx,
1626 regs64->r8);
1627 } else {
1628 uint64_t t[5];
1629
1630 fasttrap_usdt_args64(probe, regs64,
1631 sizeof (t) / sizeof (t[0]), t);
1632
1633 dtrace_probe(probe->ftp_id, t[0], t[1],
1634 t[2], t[3], t[4]);
1635 }
1636
1637 /* APPLE NOTE: Oneshot probes get one and only one chance... */
1638 if (probe->ftp_prov->ftp_provider_type == DTFTP_PROVIDER_ONESHOT) {
1639 fasttrap_tracepoint_remove(p, tp);
1640 }
1641 }
1642 }
1643
1644 /*
1645 * We're about to do a bunch of work so we cache a local copy of
1646 * the tracepoint to emulate the instruction, and then find the
1647 * tracepoint again later if we need to light up any return probes.
1648 */
1649 tp_local = *tp;
1650 lck_mtx_unlock(pid_mtx);
1651 tp = &tp_local;
1652
1653 /*
1654 * Set the program counter to appear as though the traced instruction
1655 * had completely executed. This ensures that fasttrap_getreg() will
1656 * report the expected value for REG_RIP.
1657 */
1658 regs64->isf.rip = pc + tp->ftt_size;
1659
1660 /*
1661 * If there's an is-enabled probe connected to this tracepoint it
1662 * means that there was a 'xorl %eax, %eax' or 'xorq %rax, %rax'
1663 * instruction that was placed there by DTrace when the binary was
1664 * linked. As this probe is, in fact, enabled, we need to stuff 1
1665 * into %eax or %rax. Accordingly, we can bypass all the instruction
1666 * emulation logic since we know the inevitable result. It's possible
1667 * that a user could construct a scenario where the 'is-enabled'
1668 * probe was on some other instruction, but that would be a rather
1669 * exotic way to shoot oneself in the foot.
1670 */
1671 if (is_enabled) {
1672 regs64->rax = 1;
1673 new_pc = regs64->isf.rip;
1674 goto done;
1675 }
1676
1677 /*
1678 * We emulate certain types of instructions to ensure correctness
1679 * (in the case of position dependent instructions) or optimize
1680 * common cases. The rest we have the thread execute back in user-
1681 * land.
1682 */
1683 switch (tp->ftt_type) {
1684 case FASTTRAP_T_RET:
1685 case FASTTRAP_T_RET16:
1686 {
1687 user_addr_t dst;
1688 user_addr_t addr;
1689 int ret;
1690
1691 /*
1692 * We have to emulate _every_ facet of the behavior of a ret
1693 * instruction including what happens if the load from %esp
1694 * fails; in that case, we send a SIGSEGV.
1695 */
1696 ret = fasttrap_fuword64((user_addr_t)regs64->isf.rsp, &dst);
1697 addr = regs64->isf.rsp + sizeof (uint64_t);
1698
1699 if (ret == -1) {
1700 fasttrap_sigsegv(p, uthread, (user_addr_t)regs64->isf.rsp);
1701 new_pc = pc;
1702 break;
1703 }
1704
1705 if (tp->ftt_type == FASTTRAP_T_RET16)
1706 addr += tp->ftt_dest;
1707
1708 regs64->isf.rsp = addr;
1709 new_pc = dst;
1710 break;
1711 }
1712
1713 case FASTTRAP_T_JCC:
1714 {
1715 uint_t taken;
1716
1717 switch (tp->ftt_code) {
1718 case FASTTRAP_JO:
1719 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_OF) != 0;
1720 break;
1721 case FASTTRAP_JNO:
1722 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_OF) == 0;
1723 break;
1724 case FASTTRAP_JB:
1725 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_CF) != 0;
1726 break;
1727 case FASTTRAP_JAE:
1728 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_CF) == 0;
1729 break;
1730 case FASTTRAP_JE:
1731 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) != 0;
1732 break;
1733 case FASTTRAP_JNE:
1734 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) == 0;
1735 break;
1736 case FASTTRAP_JBE:
1737 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_CF) != 0 ||
1738 (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) != 0;
1739 break;
1740 case FASTTRAP_JA:
1741 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_CF) == 0 &&
1742 (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) == 0;
1743 break;
1744 case FASTTRAP_JS:
1745 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_SF) != 0;
1746 break;
1747 case FASTTRAP_JNS:
1748 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_SF) == 0;
1749 break;
1750 case FASTTRAP_JP:
1751 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_PF) != 0;
1752 break;
1753 case FASTTRAP_JNP:
1754 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_PF) == 0;
1755 break;
1756 case FASTTRAP_JL:
1757 taken = ((regs64->isf.rflags & FASTTRAP_EFLAGS_SF) == 0) !=
1758 ((regs64->isf.rflags & FASTTRAP_EFLAGS_OF) == 0);
1759 break;
1760 case FASTTRAP_JGE:
1761 taken = ((regs64->isf.rflags & FASTTRAP_EFLAGS_SF) == 0) ==
1762 ((regs64->isf.rflags & FASTTRAP_EFLAGS_OF) == 0);
1763 break;
1764 case FASTTRAP_JLE:
1765 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) != 0 ||
1766 ((regs64->isf.rflags & FASTTRAP_EFLAGS_SF) == 0) !=
1767 ((regs64->isf.rflags & FASTTRAP_EFLAGS_OF) == 0);
1768 break;
1769 case FASTTRAP_JG:
1770 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) == 0 &&
1771 ((regs64->isf.rflags & FASTTRAP_EFLAGS_SF) == 0) ==
1772 ((regs64->isf.rflags & FASTTRAP_EFLAGS_OF) == 0);
1773 break;
1774 default:
1775 taken = FALSE;
1776 }
1777
1778 if (taken)
1779 new_pc = tp->ftt_dest;
1780 else
1781 new_pc = pc + tp->ftt_size;
1782 break;
1783 }
1784
1785 case FASTTRAP_T_LOOP:
1786 {
1787 uint_t taken;
1788 uint64_t cx = regs64->rcx--;
1789
1790 switch (tp->ftt_code) {
1791 case FASTTRAP_LOOPNZ:
1792 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) == 0 &&
1793 cx != 0;
1794 break;
1795 case FASTTRAP_LOOPZ:
1796 taken = (regs64->isf.rflags & FASTTRAP_EFLAGS_ZF) != 0 &&
1797 cx != 0;
1798 break;
1799 case FASTTRAP_LOOP:
1800 taken = (cx != 0);
1801 break;
1802 default:
1803 taken = FALSE;
1804 }
1805
1806 if (taken)
1807 new_pc = tp->ftt_dest;
1808 else
1809 new_pc = pc + tp->ftt_size;
1810 break;
1811 }
1812
1813 case FASTTRAP_T_JCXZ:
1814 {
1815 uint64_t cx = regs64->rcx;
1816
1817 if (cx == 0)
1818 new_pc = tp->ftt_dest;
1819 else
1820 new_pc = pc + tp->ftt_size;
1821 break;
1822 }
1823
1824 case FASTTRAP_T_PUSHL_EBP:
1825 {
1826 user_addr_t addr = regs64->isf.rsp - sizeof (uint64_t);
1827 int ret = fasttrap_suword64(addr, (uint64_t)regs64->rbp);
1828
1829 if (ret == -1) {
1830 fasttrap_sigsegv(p, uthread, addr);
1831 new_pc = pc;
1832 break;
1833 }
1834
1835 regs64->isf.rsp = addr;
1836 new_pc = pc + tp->ftt_size;
1837 break;
1838 }
1839
1840 case FASTTRAP_T_NOP:
1841 new_pc = pc + tp->ftt_size;
1842 break;
1843
1844 case FASTTRAP_T_JMP:
1845 case FASTTRAP_T_CALL:
1846 if (tp->ftt_code == 0) {
1847 new_pc = tp->ftt_dest;
1848 } else {
1849 user_addr_t value, addr = tp->ftt_dest;
1850
1851 if (tp->ftt_base != FASTTRAP_NOREG)
1852 addr += fasttrap_getreg(regs, tp->ftt_base);
1853 if (tp->ftt_index != FASTTRAP_NOREG)
1854 addr += fasttrap_getreg(regs, tp->ftt_index) <<
1855 tp->ftt_scale;
1856
1857 if (tp->ftt_code == 1) {
1858 /*
1859 * If there's a segment prefix for this
1860 * instruction, we'll need to check permissions
1861 * and bounds on the given selector, and adjust
1862 * the address accordingly.
1863 */
1864 if (tp->ftt_segment != FASTTRAP_SEG_NONE &&
1865 fasttrap_do_seg(tp, regs, &addr) != 0) {
1866 fasttrap_sigsegv(p, uthread, addr);
1867 new_pc = pc;
1868 break;
1869 }
1870
1871 if (fasttrap_fuword64(addr, &value) == -1) {
1872 fasttrap_sigsegv(p, uthread, addr);
1873 new_pc = pc;
1874 break;
1875 }
1876 new_pc = value;
1877 } else {
1878 new_pc = addr;
1879 }
1880 }
1881
1882 /*
1883 * If this is a call instruction, we need to push the return
1884 * address onto the stack. If this fails, we send the process
1885 * a SIGSEGV and reset the pc to emulate what would happen if
1886 * this instruction weren't traced.
1887 */
1888 if (tp->ftt_type == FASTTRAP_T_CALL) {
1889 user_addr_t addr = regs64->isf.rsp - sizeof (uint64_t);
1890 int ret = fasttrap_suword64(addr, pc + tp->ftt_size);
1891
1892 if (ret == -1) {
1893 fasttrap_sigsegv(p, uthread, addr);
1894 new_pc = pc;
1895 break;
1896 }
1897
1898 regs64->isf.rsp = addr;
1899 }
1900 break;
1901
1902 case FASTTRAP_T_COMMON:
1903 {
1904 user_addr_t addr;
1905 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 22];
1906 uint_t i = 0;
1907
1908 /*
1909 * Generic Instruction Tracing
1910 * ---------------------------
1911 *
1912 * This is the layout of the scratch space in the user-land
1913 * thread structure for our generated instructions.
1914 *
1915 * 32-bit mode bytes
1916 * ------------------------ -----
1917 * a: <original instruction> <= 15
1918 * jmp <pc + tp->ftt_size> 5
1919 * b: <original instrction> <= 15
1920 * int T_DTRACE_RET 2
1921 * -----
1922 * <= 37
1923 *
1924 * 64-bit mode bytes
1925 * ------------------------ -----
1926 * a: <original instruction> <= 15
1927 * jmp 0(%rip) 6
1928 * <pc + tp->ftt_size> 8
1929 * b: <original instruction> <= 15
1930 * int T_DTRACE_RET 2
1931 * -----
1932 * <= 46
1933 *
1934 * The %pc is set to a, and curthread->t_dtrace_astpc is set
1935 * to b. If we encounter a signal on the way out of the
1936 * kernel, trap() will set %pc to curthread->t_dtrace_astpc
1937 * so that we execute the original instruction and re-enter
1938 * the kernel rather than redirecting to the next instruction.
1939 *
1940 * If there are return probes (so we know that we're going to
1941 * need to reenter the kernel after executing the original
1942 * instruction), the scratch space will just contain the
1943 * original instruction followed by an interrupt -- the same
1944 * data as at b.
1945 *
1946 * %rip-relative Addressing
1947 * ------------------------
1948 *
1949 * There's a further complication in 64-bit mode due to %rip-
1950 * relative addressing. While this is clearly a beneficial
1951 * architectural decision for position independent code, it's
1952 * hard not to see it as a personal attack against the pid
1953 * provider since before there was a relatively small set of
1954 * instructions to emulate; with %rip-relative addressing,
1955 * almost every instruction can potentially depend on the
1956 * address at which it's executed. Rather than emulating
1957 * the broad spectrum of instructions that can now be
1958 * position dependent, we emulate jumps and others as in
1959 * 32-bit mode, and take a different tack for instructions
1960 * using %rip-relative addressing.
1961 *
1962 * For every instruction that uses the ModRM byte, the
1963 * in-kernel disassembler reports its location. We use the
1964 * ModRM byte to identify that an instruction uses
1965 * %rip-relative addressing and to see what other registers
1966 * the instruction uses. To emulate those instructions,
1967 * we modify the instruction to be %rax-relative rather than
1968 * %rip-relative (or %rcx-relative if the instruction uses
1969 * %rax; or %r8- or %r9-relative if the REX.B is present so
1970 * we don't have to rewrite the REX prefix). We then load
1971 * the value that %rip would have been into the scratch
1972 * register and generate an instruction to reset the scratch
1973 * register back to its original value. The instruction
1974 * sequence looks like this:
1975 *
1976 * 64-mode %rip-relative bytes
1977 * ------------------------ -----
1978 * a: <modified instruction> <= 15
1979 * movq $<value>, %<scratch> 6
1980 * jmp 0(%rip) 6
1981 * <pc + tp->ftt_size> 8
1982 * b: <modified instruction> <= 15
1983 * int T_DTRACE_RET 2
1984 * -----
1985 * 52
1986 *
1987 * We set curthread->t_dtrace_regv so that upon receiving
1988 * a signal we can reset the value of the scratch register.
1989 */
1990
1991 addr = uthread->t_dtrace_scratch->addr;
1992
1993 if (addr == 0LL) {
1994 fasttrap_sigtrap(p, uthread, pc); // Should be killing target proc
1995 new_pc = pc;
1996 break;
1997 }
1998
1999 ASSERT(tp->ftt_size < FASTTRAP_MAX_INSTR_SIZE);
2000
2001 uthread->t_dtrace_scrpc = addr;
2002 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
2003 i += tp->ftt_size;
2004
2005 if (tp->ftt_ripmode != 0) {
2006 uint64_t* reg;
2007
2008 ASSERT(tp->ftt_ripmode &
2009 (FASTTRAP_RIP_1 | FASTTRAP_RIP_2));
2010
2011 /*
2012 * If this was a %rip-relative instruction, we change
2013 * it to be either a %rax- or %rcx-relative
2014 * instruction (depending on whether those registers
2015 * are used as another operand; or %r8- or %r9-
2016 * relative depending on the value of REX.B). We then
2017 * set that register and generate a movq instruction
2018 * to reset the value.
2019 */
2020 if (tp->ftt_ripmode & FASTTRAP_RIP_X)
2021 scratch[i++] = FASTTRAP_REX(1, 0, 0, 1);
2022 else
2023 scratch[i++] = FASTTRAP_REX(1, 0, 0, 0);
2024
2025 if (tp->ftt_ripmode & FASTTRAP_RIP_1)
2026 scratch[i++] = FASTTRAP_MOV_EAX;
2027 else
2028 scratch[i++] = FASTTRAP_MOV_ECX;
2029
2030 switch (tp->ftt_ripmode) {
2031 case FASTTRAP_RIP_1:
2032 reg = &regs64->rax;
2033 uthread->t_dtrace_reg = REG_RAX;
2034 break;
2035 case FASTTRAP_RIP_2:
2036 reg = &regs64->rcx;
2037 uthread->t_dtrace_reg = REG_RCX;
2038 break;
2039 case FASTTRAP_RIP_1 | FASTTRAP_RIP_X:
2040 reg = &regs64->r8;
2041 uthread->t_dtrace_reg = REG_R8;
2042 break;
2043 case FASTTRAP_RIP_2 | FASTTRAP_RIP_X:
2044 reg = &regs64->r9;
2045 uthread->t_dtrace_reg = REG_R9;
2046 break;
2047 default:
2048 reg = NULL;
2049 panic("unhandled ripmode in fasttrap_pid_probe64");
2050 }
2051
2052 /* LINTED - alignment */
2053 *(uint64_t *)&scratch[i] = *reg;
2054 uthread->t_dtrace_regv = *reg;
2055 *reg = pc + tp->ftt_size;
2056 i += sizeof (uint64_t);
2057 }
2058
2059 /*
2060 * Generate the branch instruction to what would have
2061 * normally been the subsequent instruction. In 32-bit mode,
2062 * this is just a relative branch; in 64-bit mode this is a
2063 * %rip-relative branch that loads the 64-bit pc value
2064 * immediately after the jmp instruction.
2065 */
2066 scratch[i++] = FASTTRAP_GROUP5_OP;
2067 scratch[i++] = FASTTRAP_MODRM(0, 4, 5);
2068 /* LINTED - alignment */
2069 *(uint32_t *)&scratch[i] = 0;
2070 i += sizeof (uint32_t);
2071 /* LINTED - alignment */
2072 *(uint64_t *)&scratch[i] = pc + tp->ftt_size;
2073 i += sizeof (uint64_t);
2074
2075 uthread->t_dtrace_astpc = addr + i;
2076 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
2077 i += tp->ftt_size;
2078 scratch[i++] = FASTTRAP_INT;
2079 scratch[i++] = T_DTRACE_RET;
2080
2081 ASSERT(i <= sizeof (scratch));
2082
2083 if (fasttrap_copyout(scratch, addr, i)) {
2084 fasttrap_sigtrap(p, uthread, pc);
2085 new_pc = pc;
2086 break;
2087 }
2088
2089 if (tp->ftt_retids != NULL) {
2090 uthread->t_dtrace_step = 1;
2091 uthread->t_dtrace_ret = 1;
2092 new_pc = uthread->t_dtrace_astpc;
2093 } else {
2094 new_pc = uthread->t_dtrace_scrpc;
2095 }
2096
2097 uthread->t_dtrace_pc = pc;
2098 uthread->t_dtrace_npc = pc + tp->ftt_size;
2099 uthread->t_dtrace_on = 1;
2100 break;
2101 }
2102
2103 default:
2104 panic("fasttrap: mishandled an instruction");
2105 }
2106
2107 done:
2108 /*
2109 * APPLE NOTE:
2110 *
2111 * We're setting this earlier than Solaris does, to get a "correct"
2112 * ustack() output. In the Sun code, a() -> b() -> c() -> d() is
2113 * reported at: d, b, a. The new way gives c, b, a, which is closer
2114 * to correct, as the return instruction has already exectued.
2115 */
2116 regs64->isf.rip = new_pc;
2117
2118
2119 /*
2120 * If there were no return probes when we first found the tracepoint,
2121 * we should feel no obligation to honor any return probes that were
2122 * subsequently enabled -- they'll just have to wait until the next
2123 * time around.
2124 */
2125 if (tp->ftt_retids != NULL) {
2126 /*
2127 * We need to wait until the results of the instruction are
2128 * apparent before invoking any return probes. If this
2129 * instruction was emulated we can just call
2130 * fasttrap_return_common(); if it needs to be executed, we
2131 * need to wait until the user thread returns to the kernel.
2132 */
2133 if (tp->ftt_type != FASTTRAP_T_COMMON) {
2134 fasttrap_return_common(regs, pc, pid, new_pc);
2135 } else {
2136 ASSERT(uthread->t_dtrace_ret != 0);
2137 ASSERT(uthread->t_dtrace_pc == pc);
2138 ASSERT(uthread->t_dtrace_scrpc != 0);
2139 ASSERT(new_pc == uthread->t_dtrace_astpc);
2140 }
2141 }
2142
2143 return (0);
2144 }
2145
2146 int
2147 fasttrap_pid_probe(x86_saved_state_t *regs)
2148 {
2149 if (is_saved_state64(regs))
2150 return fasttrap_pid_probe64(regs);
2151
2152 return fasttrap_pid_probe32(regs);
2153 }
2154
2155 int
2156 fasttrap_return_probe(x86_saved_state_t *regs)
2157 {
2158 x86_saved_state64_t *regs64;
2159 x86_saved_state32_t *regs32;
2160 unsigned int p_model;
2161
2162 if (is_saved_state64(regs)) {
2163 regs64 = saved_state64(regs);
2164 regs32 = NULL;
2165 p_model = DATAMODEL_LP64;
2166 } else {
2167 regs64 = NULL;
2168 regs32 = saved_state32(regs);
2169 p_model = DATAMODEL_ILP32;
2170 }
2171
2172 proc_t *p = current_proc();
2173 uthread_t uthread = (uthread_t)get_bsdthread_info(current_thread());
2174 user_addr_t pc = uthread->t_dtrace_pc;
2175 user_addr_t npc = uthread->t_dtrace_npc;
2176
2177 uthread->t_dtrace_pc = 0;
2178 uthread->t_dtrace_npc = 0;
2179 uthread->t_dtrace_scrpc = 0;
2180 uthread->t_dtrace_astpc = 0;
2181
2182 /*
2183 * Treat a child created by a call to vfork(2) as if it were its
2184 * parent. We know that there's only one thread of control in such a
2185 * process: this one.
2186 */
2187 /*
2188 * APPLE NOTE: Terry says: "You need to hold the process locks (currently: kernel funnel) for this traversal"
2189 * How do we assert this?
2190 */
2191 while (p->p_lflag & P_LINVFORK) {
2192 p = p->p_pptr;
2193 }
2194
2195 /*
2196 * We set rp->r_pc to the address of the traced instruction so
2197 * that it appears to dtrace_probe() that we're on the original
2198 * instruction, and so that the user can't easily detect our
2199 * complex web of lies. dtrace_return_probe() (our caller)
2200 * will correctly set %pc after we return.
2201 */
2202 if (p_model == DATAMODEL_LP64)
2203 regs64->isf.rip = pc;
2204 else
2205 regs32->eip = pc;
2206
2207 fasttrap_return_common(regs, pc, p->p_pid, npc);
2208
2209 return (0);
2210 }
2211
2212 uint64_t
2213 fasttrap_pid_getarg(void *arg, dtrace_id_t id, void *parg, int argno,
2214 int aframes)
2215 {
2216 pal_register_cache_state(current_thread(), VALID);
2217 #pragma unused(arg, id, parg, aframes)
2218 return (fasttrap_anarg((x86_saved_state_t *)find_user_regs(current_thread()), 1, argno));
2219 }
2220
2221 uint64_t
2222 fasttrap_usdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno,
2223 int aframes)
2224 {
2225 pal_register_cache_state(current_thread(), VALID);
2226 #pragma unused(arg, id, parg, aframes)
2227 return (fasttrap_anarg((x86_saved_state_t *)find_user_regs(current_thread()), 0, argno));
2228 }
2229
2230 /*
2231 * APPLE NOTE: See comments by regmap array definition. We are cheating
2232 * when returning 32 bit registers.
2233 */
2234 static user_addr_t
2235 fasttrap_getreg(x86_saved_state_t *regs, uint_t reg)
2236 {
2237 if (is_saved_state64(regs)) {
2238 x86_saved_state64_t *regs64 = saved_state64(regs);
2239
2240 switch (reg) {
2241 case REG_RAX: return regs64->rax;
2242 case REG_RCX: return regs64->rcx;
2243 case REG_RDX: return regs64->rdx;
2244 case REG_RBX: return regs64->rbx;
2245 case REG_RSP: return regs64->isf.rsp;
2246 case REG_RBP: return regs64->rbp;
2247 case REG_RSI: return regs64->rsi;
2248 case REG_RDI: return regs64->rdi;
2249 case REG_R8: return regs64->r8;
2250 case REG_R9: return regs64->r9;
2251 case REG_R10: return regs64->r10;
2252 case REG_R11: return regs64->r11;
2253 case REG_R12: return regs64->r12;
2254 case REG_R13: return regs64->r13;
2255 case REG_R14: return regs64->r14;
2256 case REG_R15: return regs64->r15;
2257 case REG_TRAPNO: return regs64->isf.trapno;
2258 case REG_ERR: return regs64->isf.err;
2259 case REG_RIP: return regs64->isf.rip;
2260 case REG_CS: return regs64->isf.cs;
2261 case REG_RFL: return regs64->isf.rflags;
2262 case REG_SS: return regs64->isf.ss;
2263 case REG_FS: return regs64->fs;
2264 case REG_GS: return regs64->gs;
2265 case REG_ES:
2266 case REG_DS:
2267 case REG_FSBASE:
2268 case REG_GSBASE:
2269 // Important to distinguish these requests (which should be legal) from other values.
2270 panic("dtrace: unimplemented x86_64 getreg()");
2271 }
2272
2273 panic("dtrace: unhandled x86_64 getreg() constant");
2274 } else {
2275 x86_saved_state32_t *regs32 = saved_state32(regs);
2276
2277 switch (reg) {
2278 case REG_RAX: return regs32->eax;
2279 case REG_RCX: return regs32->ecx;
2280 case REG_RDX: return regs32->edx;
2281 case REG_RBX: return regs32->ebx;
2282 case REG_RSP: return regs32->uesp;
2283 case REG_RBP: return regs32->ebp;
2284 case REG_RSI: return regs32->esi;
2285 case REG_RDI: return regs32->edi;
2286 }
2287
2288 panic("dtrace: unhandled i386 getreg() constant");
2289 }
2290
2291 return 0;
2292 }
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