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