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 * Portions Copyright 2010 The FreeBSD Foundation
22 *
23 * $FreeBSD$
24 */
25
26 /*
27 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
28 * Use is subject to license terms.
29 */
30
31 #ifdef illumos
32 #pragma ident "%Z%%M% %I% %E% SMI"
33 #endif
34
35 #include <sys/fasttrap_isa.h>
36 #include <sys/fasttrap_impl.h>
37 #include <sys/dtrace.h>
38 #include <sys/dtrace_impl.h>
39 #include <sys/cmn_err.h>
40 #ifdef illumos
41 #include <sys/regset.h>
42 #include <sys/privregs.h>
43 #include <sys/segments.h>
44 #include <sys/x86_archext.h>
45 #else
46 #include <sys/types.h>
47 #include <sys/dtrace_bsd.h>
48 #include <sys/proc.h>
49 #include <sys/rmlock.h>
50 #include <cddl/dev/dtrace/dtrace_cddl.h>
51 #include <cddl/dev/dtrace/x86/regset.h>
52 #include <machine/segments.h>
53 #include <machine/reg.h>
54 #include <machine/pcb.h>
55 #endif
56 #include <sys/sysmacros.h>
57 #ifdef illumos
58 #include <sys/trap.h>
59 #include <sys/archsystm.h>
60 #else
61 #include <sys/ptrace.h>
62 #endif /* illumos */
63
64 #ifdef __i386__
65 #define r_rax r_eax
66 #define r_rbx r_ebx
67 #define r_rip r_eip
68 #define r_rflags r_eflags
69 #define r_rsp r_esp
70 #define r_rbp r_ebp
71 #endif
72
73 /*
74 * Lossless User-Land Tracing on x86
75 * ---------------------------------
76 *
77 * The execution of most instructions is not dependent on the address; for
78 * these instructions it is sufficient to copy them into the user process's
79 * address space and execute them. To effectively single-step an instruction
80 * in user-land, we copy out the following sequence of instructions to scratch
81 * space in the user thread's ulwp_t structure.
82 *
83 * We then set the program counter (%eip or %rip) to point to this scratch
84 * space. Once execution resumes, the original instruction is executed and
85 * then control flow is redirected to what was originally the subsequent
86 * instruction. If the kernel attemps to deliver a signal while single-
87 * stepping, the signal is deferred and the program counter is moved into the
88 * second sequence of instructions. The second sequence ends in a trap into
89 * the kernel where the deferred signal is then properly handled and delivered.
90 *
91 * For instructions whose execute is position dependent, we perform simple
92 * emulation. These instructions are limited to control transfer
93 * instructions in 32-bit mode, but in 64-bit mode there's the added wrinkle
94 * of %rip-relative addressing that means that almost any instruction can be
95 * position dependent. For all the details on how we emulate generic
96 * instructions included %rip-relative instructions, see the code in
97 * fasttrap_pid_probe() below where we handle instructions of type
98 * FASTTRAP_T_COMMON (under the header: Generic Instruction Tracing).
99 */
100
101 #define FASTTRAP_MODRM_MOD(modrm) (((modrm) >> 6) & 0x3)
102 #define FASTTRAP_MODRM_REG(modrm) (((modrm) >> 3) & 0x7)
103 #define FASTTRAP_MODRM_RM(modrm) ((modrm) & 0x7)
104 #define FASTTRAP_MODRM(mod, reg, rm) (((mod) << 6) | ((reg) << 3) | (rm))
105
106 #define FASTTRAP_SIB_SCALE(sib) (((sib) >> 6) & 0x3)
107 #define FASTTRAP_SIB_INDEX(sib) (((sib) >> 3) & 0x7)
108 #define FASTTRAP_SIB_BASE(sib) ((sib) & 0x7)
109
110 #define FASTTRAP_REX_W(rex) (((rex) >> 3) & 1)
111 #define FASTTRAP_REX_R(rex) (((rex) >> 2) & 1)
112 #define FASTTRAP_REX_X(rex) (((rex) >> 1) & 1)
113 #define FASTTRAP_REX_B(rex) ((rex) & 1)
114 #define FASTTRAP_REX(w, r, x, b) \
115 (0x40 | ((w) << 3) | ((r) << 2) | ((x) << 1) | (b))
116
117 /*
118 * Single-byte op-codes.
119 */
120 #define FASTTRAP_PUSHL_EBP 0x55
121
122 #define FASTTRAP_JO 0x70
123 #define FASTTRAP_JNO 0x71
124 #define FASTTRAP_JB 0x72
125 #define FASTTRAP_JAE 0x73
126 #define FASTTRAP_JE 0x74
127 #define FASTTRAP_JNE 0x75
128 #define FASTTRAP_JBE 0x76
129 #define FASTTRAP_JA 0x77
130 #define FASTTRAP_JS 0x78
131 #define FASTTRAP_JNS 0x79
132 #define FASTTRAP_JP 0x7a
133 #define FASTTRAP_JNP 0x7b
134 #define FASTTRAP_JL 0x7c
135 #define FASTTRAP_JGE 0x7d
136 #define FASTTRAP_JLE 0x7e
137 #define FASTTRAP_JG 0x7f
138
139 #define FASTTRAP_NOP 0x90
140
141 #define FASTTRAP_MOV_EAX 0xb8
142 #define FASTTRAP_MOV_ECX 0xb9
143
144 #define FASTTRAP_RET16 0xc2
145 #define FASTTRAP_RET 0xc3
146
147 #define FASTTRAP_LOOPNZ 0xe0
148 #define FASTTRAP_LOOPZ 0xe1
149 #define FASTTRAP_LOOP 0xe2
150 #define FASTTRAP_JCXZ 0xe3
151
152 #define FASTTRAP_CALL 0xe8
153 #define FASTTRAP_JMP32 0xe9
154 #define FASTTRAP_JMP8 0xeb
155
156 #define FASTTRAP_INT3 0xcc
157 #define FASTTRAP_INT 0xcd
158
159 #define FASTTRAP_2_BYTE_OP 0x0f
160 #define FASTTRAP_GROUP5_OP 0xff
161
162 /*
163 * Two-byte op-codes (second byte only).
164 */
165 #define FASTTRAP_0F_JO 0x80
166 #define FASTTRAP_0F_JNO 0x81
167 #define FASTTRAP_0F_JB 0x82
168 #define FASTTRAP_0F_JAE 0x83
169 #define FASTTRAP_0F_JE 0x84
170 #define FASTTRAP_0F_JNE 0x85
171 #define FASTTRAP_0F_JBE 0x86
172 #define FASTTRAP_0F_JA 0x87
173 #define FASTTRAP_0F_JS 0x88
174 #define FASTTRAP_0F_JNS 0x89
175 #define FASTTRAP_0F_JP 0x8a
176 #define FASTTRAP_0F_JNP 0x8b
177 #define FASTTRAP_0F_JL 0x8c
178 #define FASTTRAP_0F_JGE 0x8d
179 #define FASTTRAP_0F_JLE 0x8e
180 #define FASTTRAP_0F_JG 0x8f
181
182 #define FASTTRAP_EFLAGS_OF 0x800
183 #define FASTTRAP_EFLAGS_DF 0x400
184 #define FASTTRAP_EFLAGS_SF 0x080
185 #define FASTTRAP_EFLAGS_ZF 0x040
186 #define FASTTRAP_EFLAGS_AF 0x010
187 #define FASTTRAP_EFLAGS_PF 0x004
188 #define FASTTRAP_EFLAGS_CF 0x001
189
190 /*
191 * Instruction prefixes.
192 */
193 #define FASTTRAP_PREFIX_OPERAND 0x66
194 #define FASTTRAP_PREFIX_ADDRESS 0x67
195 #define FASTTRAP_PREFIX_CS 0x2E
196 #define FASTTRAP_PREFIX_DS 0x3E
197 #define FASTTRAP_PREFIX_ES 0x26
198 #define FASTTRAP_PREFIX_FS 0x64
199 #define FASTTRAP_PREFIX_GS 0x65
200 #define FASTTRAP_PREFIX_SS 0x36
201 #define FASTTRAP_PREFIX_LOCK 0xF0
202 #define FASTTRAP_PREFIX_REP 0xF3
203 #define FASTTRAP_PREFIX_REPNE 0xF2
204
205 #define FASTTRAP_NOREG 0xff
206
207 /*
208 * Map between instruction register encodings and the kernel constants which
209 * correspond to indicies into struct regs.
210 */
211 #ifdef __amd64
212 static const uint8_t regmap[16] = {
213 REG_RAX, REG_RCX, REG_RDX, REG_RBX, REG_RSP, REG_RBP, REG_RSI, REG_RDI,
214 REG_R8, REG_R9, REG_R10, REG_R11, REG_R12, REG_R13, REG_R14, REG_R15,
215 };
216 #else
217 static const uint8_t regmap[8] = {
218 EAX, ECX, EDX, EBX, UESP, EBP, ESI, EDI
219 };
220 #endif
221
222 static ulong_t fasttrap_getreg(struct reg *, uint_t);
223
224 static uint64_t
fasttrap_anarg(struct reg * rp,int function_entry,int argno)225 fasttrap_anarg(struct reg *rp, int function_entry, int argno)
226 {
227 uint64_t value = 0;
228 int shift = function_entry ? 1 : 0;
229
230 #ifdef __amd64
231 if (curproc->p_model == DATAMODEL_LP64) {
232 uintptr_t *stack;
233
234 /*
235 * In 64-bit mode, the first six arguments are stored in
236 * registers.
237 */
238 if (argno < 6)
239 switch (argno) {
240 case 0:
241 return (rp->r_rdi);
242 case 1:
243 return (rp->r_rsi);
244 case 2:
245 return (rp->r_rdx);
246 case 3:
247 return (rp->r_rcx);
248 case 4:
249 return (rp->r_r8);
250 case 5:
251 return (rp->r_r9);
252 }
253
254 stack = (uintptr_t *)rp->r_rsp;
255 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
256 value = dtrace_fulword(&stack[argno - 6 + shift]);
257 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR);
258 } else {
259 #endif
260 uint32_t *stack = (uint32_t *)rp->r_rsp;
261 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
262 value = dtrace_fuword32(&stack[argno + shift]);
263 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR);
264 #ifdef __amd64
265 }
266 #endif
267
268 return (value);
269 }
270
271 /*ARGSUSED*/
272 int
fasttrap_tracepoint_init(proc_t * p,fasttrap_tracepoint_t * tp,uintptr_t pc,fasttrap_probe_type_t type)273 fasttrap_tracepoint_init(proc_t *p, fasttrap_tracepoint_t *tp, uintptr_t pc,
274 fasttrap_probe_type_t type)
275 {
276 uint8_t instr[FASTTRAP_MAX_INSTR_SIZE + 10];
277 size_t len = FASTTRAP_MAX_INSTR_SIZE;
278 size_t first = MIN(len, PAGESIZE - (pc & PAGEOFFSET));
279 uint_t start = 0;
280 int rmindex, size;
281 uint8_t seg, rex = 0;
282
283 /*
284 * Read the instruction at the given address out of the process's
285 * address space. We don't have to worry about a debugger
286 * changing this instruction before we overwrite it with our trap
287 * instruction since P_PR_LOCK is set. Since instructions can span
288 * pages, we potentially read the instruction in two parts. If the
289 * second part fails, we just zero out that part of the instruction.
290 */
291 if (uread(p, &instr[0], first, pc) != 0)
292 return (-1);
293 if (len > first &&
294 uread(p, &instr[first], len - first, pc + first) != 0) {
295 bzero(&instr[first], len - first);
296 len = first;
297 }
298
299 /*
300 * If the disassembly fails, then we have a malformed instruction.
301 */
302 if ((size = dtrace_instr_size_isa(instr, p->p_model, &rmindex)) <= 0)
303 return (-1);
304
305 /*
306 * Make sure the disassembler isn't completely broken.
307 */
308 ASSERT(-1 <= rmindex && rmindex < size);
309
310 /*
311 * If the computed size is greater than the number of bytes read,
312 * then it was a malformed instruction possibly because it fell on a
313 * page boundary and the subsequent page was missing or because of
314 * some malicious user.
315 */
316 if (size > len)
317 return (-1);
318
319 tp->ftt_size = (uint8_t)size;
320 tp->ftt_segment = FASTTRAP_SEG_NONE;
321
322 /*
323 * Find the start of the instruction's opcode by processing any
324 * legacy prefixes.
325 */
326 for (;;) {
327 seg = 0;
328 switch (instr[start]) {
329 case FASTTRAP_PREFIX_SS:
330 seg++;
331 /*FALLTHRU*/
332 case FASTTRAP_PREFIX_GS:
333 seg++;
334 /*FALLTHRU*/
335 case FASTTRAP_PREFIX_FS:
336 seg++;
337 /*FALLTHRU*/
338 case FASTTRAP_PREFIX_ES:
339 seg++;
340 /*FALLTHRU*/
341 case FASTTRAP_PREFIX_DS:
342 seg++;
343 /*FALLTHRU*/
344 case FASTTRAP_PREFIX_CS:
345 seg++;
346 /*FALLTHRU*/
347 case FASTTRAP_PREFIX_OPERAND:
348 case FASTTRAP_PREFIX_ADDRESS:
349 case FASTTRAP_PREFIX_LOCK:
350 case FASTTRAP_PREFIX_REP:
351 case FASTTRAP_PREFIX_REPNE:
352 if (seg != 0) {
353 /*
354 * It's illegal for an instruction to specify
355 * two segment prefixes -- give up on this
356 * illegal instruction.
357 */
358 if (tp->ftt_segment != FASTTRAP_SEG_NONE)
359 return (-1);
360
361 tp->ftt_segment = seg;
362 }
363 start++;
364 continue;
365 }
366 break;
367 }
368
369 #ifdef __amd64
370 /*
371 * Identify the REX prefix on 64-bit processes.
372 */
373 if (p->p_model == DATAMODEL_LP64 && (instr[start] & 0xf0) == 0x40)
374 rex = instr[start++];
375 #endif
376
377 /*
378 * Now that we're pretty sure that the instruction is okay, copy the
379 * valid part to the tracepoint.
380 */
381 bcopy(instr, tp->ftt_instr, FASTTRAP_MAX_INSTR_SIZE);
382
383 tp->ftt_type = FASTTRAP_T_COMMON;
384 if (instr[start] == FASTTRAP_2_BYTE_OP) {
385 switch (instr[start + 1]) {
386 case FASTTRAP_0F_JO:
387 case FASTTRAP_0F_JNO:
388 case FASTTRAP_0F_JB:
389 case FASTTRAP_0F_JAE:
390 case FASTTRAP_0F_JE:
391 case FASTTRAP_0F_JNE:
392 case FASTTRAP_0F_JBE:
393 case FASTTRAP_0F_JA:
394 case FASTTRAP_0F_JS:
395 case FASTTRAP_0F_JNS:
396 case FASTTRAP_0F_JP:
397 case FASTTRAP_0F_JNP:
398 case FASTTRAP_0F_JL:
399 case FASTTRAP_0F_JGE:
400 case FASTTRAP_0F_JLE:
401 case FASTTRAP_0F_JG:
402 tp->ftt_type = FASTTRAP_T_JCC;
403 tp->ftt_code = (instr[start + 1] & 0x0f) | FASTTRAP_JO;
404 tp->ftt_dest = pc + tp->ftt_size +
405 /* LINTED - alignment */
406 *(int32_t *)&instr[start + 2];
407 break;
408 }
409 } else if (instr[start] == FASTTRAP_GROUP5_OP) {
410 uint_t mod = FASTTRAP_MODRM_MOD(instr[start + 1]);
411 uint_t reg = FASTTRAP_MODRM_REG(instr[start + 1]);
412 uint_t rm = FASTTRAP_MODRM_RM(instr[start + 1]);
413
414 if (reg == 2 || reg == 4) {
415 uint_t i, sz;
416
417 if (reg == 2)
418 tp->ftt_type = FASTTRAP_T_CALL;
419 else
420 tp->ftt_type = FASTTRAP_T_JMP;
421
422 if (mod == 3)
423 tp->ftt_code = 2;
424 else
425 tp->ftt_code = 1;
426
427 ASSERT(p->p_model == DATAMODEL_LP64 || rex == 0);
428
429 /*
430 * See AMD x86-64 Architecture Programmer's Manual
431 * Volume 3, Section 1.2.7, Table 1-12, and
432 * Appendix A.3.1, Table A-15.
433 */
434 if (mod != 3 && rm == 4) {
435 uint8_t sib = instr[start + 2];
436 uint_t index = FASTTRAP_SIB_INDEX(sib);
437 uint_t base = FASTTRAP_SIB_BASE(sib);
438
439 tp->ftt_scale = FASTTRAP_SIB_SCALE(sib);
440
441 tp->ftt_index = (index == 4) ?
442 FASTTRAP_NOREG :
443 regmap[index | (FASTTRAP_REX_X(rex) << 3)];
444 tp->ftt_base = (mod == 0 && base == 5) ?
445 FASTTRAP_NOREG :
446 regmap[base | (FASTTRAP_REX_B(rex) << 3)];
447
448 i = 3;
449 sz = mod == 1 ? 1 : 4;
450 } else {
451 /*
452 * In 64-bit mode, mod == 0 and r/m == 5
453 * denotes %rip-relative addressing; in 32-bit
454 * mode, the base register isn't used. In both
455 * modes, there is a 32-bit operand.
456 */
457 if (mod == 0 && rm == 5) {
458 #ifdef __amd64
459 if (p->p_model == DATAMODEL_LP64)
460 tp->ftt_base = REG_RIP;
461 else
462 #endif
463 tp->ftt_base = FASTTRAP_NOREG;
464 sz = 4;
465 } else {
466 uint8_t base = rm |
467 (FASTTRAP_REX_B(rex) << 3);
468
469 tp->ftt_base = regmap[base];
470 sz = mod == 1 ? 1 : mod == 2 ? 4 : 0;
471 }
472 tp->ftt_index = FASTTRAP_NOREG;
473 i = 2;
474 }
475
476 if (sz == 1) {
477 tp->ftt_dest = *(int8_t *)&instr[start + i];
478 } else if (sz == 4) {
479 /* LINTED - alignment */
480 tp->ftt_dest = *(int32_t *)&instr[start + i];
481 } else {
482 tp->ftt_dest = 0;
483 }
484 }
485 } else {
486 switch (instr[start]) {
487 case FASTTRAP_RET:
488 tp->ftt_type = FASTTRAP_T_RET;
489 break;
490
491 case FASTTRAP_RET16:
492 tp->ftt_type = FASTTRAP_T_RET16;
493 /* LINTED - alignment */
494 tp->ftt_dest = *(uint16_t *)&instr[start + 1];
495 break;
496
497 case FASTTRAP_JO:
498 case FASTTRAP_JNO:
499 case FASTTRAP_JB:
500 case FASTTRAP_JAE:
501 case FASTTRAP_JE:
502 case FASTTRAP_JNE:
503 case FASTTRAP_JBE:
504 case FASTTRAP_JA:
505 case FASTTRAP_JS:
506 case FASTTRAP_JNS:
507 case FASTTRAP_JP:
508 case FASTTRAP_JNP:
509 case FASTTRAP_JL:
510 case FASTTRAP_JGE:
511 case FASTTRAP_JLE:
512 case FASTTRAP_JG:
513 tp->ftt_type = FASTTRAP_T_JCC;
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_LOOPNZ:
520 case FASTTRAP_LOOPZ:
521 case FASTTRAP_LOOP:
522 tp->ftt_type = FASTTRAP_T_LOOP;
523 tp->ftt_code = instr[start];
524 tp->ftt_dest = pc + tp->ftt_size +
525 (int8_t)instr[start + 1];
526 break;
527
528 case FASTTRAP_JCXZ:
529 tp->ftt_type = FASTTRAP_T_JCXZ;
530 tp->ftt_dest = pc + tp->ftt_size +
531 (int8_t)instr[start + 1];
532 break;
533
534 case FASTTRAP_CALL:
535 tp->ftt_type = FASTTRAP_T_CALL;
536 tp->ftt_dest = pc + tp->ftt_size +
537 /* LINTED - alignment */
538 *(int32_t *)&instr[start + 1];
539 tp->ftt_code = 0;
540 break;
541
542 case FASTTRAP_JMP32:
543 tp->ftt_type = FASTTRAP_T_JMP;
544 tp->ftt_dest = pc + tp->ftt_size +
545 /* LINTED - alignment */
546 *(int32_t *)&instr[start + 1];
547 break;
548 case FASTTRAP_JMP8:
549 tp->ftt_type = FASTTRAP_T_JMP;
550 tp->ftt_dest = pc + tp->ftt_size +
551 (int8_t)instr[start + 1];
552 break;
553
554 case FASTTRAP_PUSHL_EBP:
555 if (start == 0)
556 tp->ftt_type = FASTTRAP_T_PUSHL_EBP;
557 break;
558
559 case FASTTRAP_NOP:
560 #ifdef __amd64
561 ASSERT(p->p_model == DATAMODEL_LP64 || rex == 0);
562
563 /*
564 * On amd64 we have to be careful not to confuse a nop
565 * (actually xchgl %eax, %eax) with an instruction using
566 * the same opcode, but that does something different
567 * (e.g. xchgl %r8d, %eax or xcghq %r8, %rax).
568 */
569 if (FASTTRAP_REX_B(rex) == 0)
570 #endif
571 tp->ftt_type = FASTTRAP_T_NOP;
572 break;
573
574 case FASTTRAP_INT3:
575 /*
576 * The pid provider shares the int3 trap with debugger
577 * breakpoints so we can't instrument them.
578 */
579 ASSERT(instr[start] == FASTTRAP_INSTR);
580 return (-1);
581
582 case FASTTRAP_INT:
583 /*
584 * Interrupts seem like they could be traced with
585 * no negative implications, but it's possible that
586 * a thread could be redirected by the trap handling
587 * code which would eventually return to the
588 * instruction after the interrupt. If the interrupt
589 * were in our scratch space, the subsequent
590 * instruction might be overwritten before we return.
591 * Accordingly we refuse to instrument any interrupt.
592 */
593 return (-1);
594 }
595 }
596
597 #ifdef __amd64
598 if (p->p_model == DATAMODEL_LP64 && tp->ftt_type == FASTTRAP_T_COMMON) {
599 /*
600 * If the process is 64-bit and the instruction type is still
601 * FASTTRAP_T_COMMON -- meaning we're going to copy it out an
602 * execute it -- we need to watch for %rip-relative
603 * addressing mode. See the portion of fasttrap_pid_probe()
604 * below where we handle tracepoints with type
605 * FASTTRAP_T_COMMON for how we emulate instructions that
606 * employ %rip-relative addressing.
607 */
608 if (rmindex != -1) {
609 uint_t mod = FASTTRAP_MODRM_MOD(instr[rmindex]);
610 uint_t reg = FASTTRAP_MODRM_REG(instr[rmindex]);
611 uint_t rm = FASTTRAP_MODRM_RM(instr[rmindex]);
612
613 ASSERT(rmindex > start);
614
615 if (mod == 0 && rm == 5) {
616 /*
617 * We need to be sure to avoid other
618 * registers used by this instruction. While
619 * the reg field may determine the op code
620 * rather than denoting a register, assuming
621 * that it denotes a register is always safe.
622 * We leave the REX field intact and use
623 * whatever value's there for simplicity.
624 */
625 if (reg != 0) {
626 tp->ftt_ripmode = FASTTRAP_RIP_1 |
627 (FASTTRAP_RIP_X *
628 FASTTRAP_REX_B(rex));
629 rm = 0;
630 } else {
631 tp->ftt_ripmode = FASTTRAP_RIP_2 |
632 (FASTTRAP_RIP_X *
633 FASTTRAP_REX_B(rex));
634 rm = 1;
635 }
636
637 tp->ftt_modrm = tp->ftt_instr[rmindex];
638 tp->ftt_instr[rmindex] =
639 FASTTRAP_MODRM(2, reg, rm);
640 }
641 }
642 }
643 #endif
644
645 return (0);
646 }
647
648 int
fasttrap_tracepoint_install(proc_t * p,fasttrap_tracepoint_t * tp)649 fasttrap_tracepoint_install(proc_t *p, fasttrap_tracepoint_t *tp)
650 {
651 fasttrap_instr_t instr = FASTTRAP_INSTR;
652
653 if (uwrite(p, &instr, 1, tp->ftt_pc) != 0)
654 return (-1);
655
656 return (0);
657 }
658
659 int
fasttrap_tracepoint_remove(proc_t * p,fasttrap_tracepoint_t * tp)660 fasttrap_tracepoint_remove(proc_t *p, fasttrap_tracepoint_t *tp)
661 {
662 uint8_t instr;
663
664 /*
665 * Distinguish between read or write failures and a changed
666 * instruction.
667 */
668 if (uread(p, &instr, 1, tp->ftt_pc) != 0)
669 return (0);
670 if (instr != FASTTRAP_INSTR)
671 return (0);
672 if (uwrite(p, &tp->ftt_instr[0], 1, tp->ftt_pc) != 0)
673 return (-1);
674
675 return (0);
676 }
677
678 #ifdef __amd64
679 static uintptr_t
fasttrap_fulword_noerr(const void * uaddr)680 fasttrap_fulword_noerr(const void *uaddr)
681 {
682 uintptr_t ret;
683
684 if ((ret = fasttrap_fulword(uaddr)) != -1)
685 return (ret);
686
687 return (0);
688 }
689 #endif
690
691 static uint32_t
fasttrap_fuword32_noerr(const void * uaddr)692 fasttrap_fuword32_noerr(const void *uaddr)
693 {
694 uint32_t ret;
695
696 if ((ret = fasttrap_fuword32(uaddr)) != -1)
697 return (ret);
698
699 return (0);
700 }
701
702 static void
fasttrap_return_common(struct reg * rp,uintptr_t pc,pid_t pid,uintptr_t new_pc)703 fasttrap_return_common(struct reg *rp, uintptr_t pc, pid_t pid,
704 uintptr_t new_pc)
705 {
706 fasttrap_tracepoint_t *tp;
707 fasttrap_bucket_t *bucket;
708 fasttrap_id_t *id;
709 #ifdef illumos
710 kmutex_t *pid_mtx;
711
712 pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
713 mutex_enter(pid_mtx);
714 #else
715 struct rm_priotracker tracker;
716
717 rm_rlock(&fasttrap_tp_lock, &tracker);
718 #endif
719 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
720
721 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
722 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
723 tp->ftt_proc->ftpc_acount != 0)
724 break;
725 }
726
727 /*
728 * Don't sweat it if we can't find the tracepoint again; unlike
729 * when we're in fasttrap_pid_probe(), finding the tracepoint here
730 * is not essential to the correct execution of the process.
731 */
732 if (tp == NULL) {
733 #ifdef illumos
734 mutex_exit(pid_mtx);
735 #else
736 rm_runlock(&fasttrap_tp_lock, &tracker);
737 #endif
738 return;
739 }
740
741 for (id = tp->ftt_retids; id != NULL; id = id->fti_next) {
742 /*
743 * If there's a branch that could act as a return site, we
744 * need to trace it, and check here if the program counter is
745 * external to the function.
746 */
747 if (tp->ftt_type != FASTTRAP_T_RET &&
748 tp->ftt_type != FASTTRAP_T_RET16 &&
749 new_pc - id->fti_probe->ftp_faddr <
750 id->fti_probe->ftp_fsize)
751 continue;
752
753 dtrace_probe(id->fti_probe->ftp_id,
754 pc - id->fti_probe->ftp_faddr,
755 rp->r_rax, rp->r_rbx, 0, 0);
756 }
757
758 #ifdef illumos
759 mutex_exit(pid_mtx);
760 #else
761 rm_runlock(&fasttrap_tp_lock, &tracker);
762 #endif
763 }
764
765 static void
fasttrap_sigsegv(proc_t * p,kthread_t * t,uintptr_t addr)766 fasttrap_sigsegv(proc_t *p, kthread_t *t, uintptr_t addr)
767 {
768 #ifdef illumos
769 sigqueue_t *sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
770
771 sqp->sq_info.si_signo = SIGSEGV;
772 sqp->sq_info.si_code = SEGV_MAPERR;
773 sqp->sq_info.si_addr = (caddr_t)addr;
774
775 mutex_enter(&p->p_lock);
776 sigaddqa(p, t, sqp);
777 mutex_exit(&p->p_lock);
778
779 if (t != NULL)
780 aston(t);
781 #else
782 ksiginfo_t *ksi = kmem_zalloc(sizeof (ksiginfo_t), KM_SLEEP);
783
784 ksiginfo_init(ksi);
785 ksi->ksi_signo = SIGSEGV;
786 ksi->ksi_code = SEGV_MAPERR;
787 ksi->ksi_addr = (caddr_t)addr;
788 (void) tdksignal(t, SIGSEGV, ksi);
789 #endif
790 }
791
792 #ifdef __amd64
793 static void
fasttrap_usdt_args64(fasttrap_probe_t * probe,struct reg * rp,int argc,uintptr_t * argv)794 fasttrap_usdt_args64(fasttrap_probe_t *probe, struct reg *rp, int argc,
795 uintptr_t *argv)
796 {
797 int i, x, cap = MIN(argc, probe->ftp_nargs);
798 uintptr_t *stack = (uintptr_t *)rp->r_rsp;
799
800 for (i = 0; i < cap; i++) {
801 x = probe->ftp_argmap[i];
802
803 if (x < 6)
804 argv[i] = (&rp->r_rdi)[x];
805 else
806 argv[i] = fasttrap_fulword_noerr(&stack[x]);
807 }
808
809 for (; i < argc; i++) {
810 argv[i] = 0;
811 }
812 }
813 #endif
814
815 static void
fasttrap_usdt_args32(fasttrap_probe_t * probe,struct reg * rp,int argc,uint32_t * argv)816 fasttrap_usdt_args32(fasttrap_probe_t *probe, struct reg *rp, int argc,
817 uint32_t *argv)
818 {
819 int i, x, cap = MIN(argc, probe->ftp_nargs);
820 uint32_t *stack = (uint32_t *)rp->r_rsp;
821
822 for (i = 0; i < cap; i++) {
823 x = probe->ftp_argmap[i];
824
825 argv[i] = fasttrap_fuword32_noerr(&stack[x]);
826 }
827
828 for (; i < argc; i++) {
829 argv[i] = 0;
830 }
831 }
832
833 static int
fasttrap_do_seg(fasttrap_tracepoint_t * tp,struct reg * rp,uintptr_t * addr)834 fasttrap_do_seg(fasttrap_tracepoint_t *tp, struct reg *rp, uintptr_t *addr)
835 {
836 proc_t *p = curproc;
837 #ifdef __i386__
838 struct segment_descriptor *desc;
839 #else
840 struct user_segment_descriptor *desc;
841 #endif
842 uint16_t sel = 0, ndx, type;
843 uintptr_t limit;
844
845 switch (tp->ftt_segment) {
846 case FASTTRAP_SEG_CS:
847 sel = rp->r_cs;
848 break;
849 case FASTTRAP_SEG_DS:
850 sel = rp->r_ds;
851 break;
852 case FASTTRAP_SEG_ES:
853 sel = rp->r_es;
854 break;
855 case FASTTRAP_SEG_FS:
856 sel = rp->r_fs;
857 break;
858 case FASTTRAP_SEG_GS:
859 sel = rp->r_gs;
860 break;
861 case FASTTRAP_SEG_SS:
862 sel = rp->r_ss;
863 break;
864 }
865
866 /*
867 * Make sure the given segment register specifies a user priority
868 * selector rather than a kernel selector.
869 */
870 if (ISPL(sel) != SEL_UPL)
871 return (-1);
872
873 ndx = IDXSEL(sel);
874
875 /*
876 * Check the bounds and grab the descriptor out of the specified
877 * descriptor table.
878 */
879 if (ISLDT(sel)) {
880 #ifdef __i386__
881 if (ndx > p->p_md.md_ldt->ldt_len)
882 return (-1);
883
884 desc = (struct segment_descriptor *)
885 p->p_md.md_ldt[ndx].ldt_base;
886 #else
887 if (ndx > max_ldt_segment)
888 return (-1);
889
890 desc = (struct user_segment_descriptor *)
891 p->p_md.md_ldt[ndx].ldt_base;
892 #endif
893
894 } else {
895 if (ndx >= NGDT)
896 return (-1);
897
898 #ifdef __i386__
899 desc = &gdt[ndx].sd;
900 #else
901 desc = &gdt[ndx];
902 #endif
903 }
904
905 /*
906 * The descriptor must have user privilege level and it must be
907 * present in memory.
908 */
909 if (desc->sd_dpl != SEL_UPL || desc->sd_p != 1)
910 return (-1);
911
912 type = desc->sd_type;
913
914 /*
915 * If the S bit in the type field is not set, this descriptor can
916 * only be used in system context.
917 */
918 if ((type & 0x10) != 0x10)
919 return (-1);
920
921 limit = USD_GETLIMIT(desc) * (desc->sd_gran ? PAGESIZE : 1);
922
923 if (tp->ftt_segment == FASTTRAP_SEG_CS) {
924 /*
925 * The code/data bit and readable bit must both be set.
926 */
927 if ((type & 0xa) != 0xa)
928 return (-1);
929
930 if (*addr > limit)
931 return (-1);
932 } else {
933 /*
934 * The code/data bit must be clear.
935 */
936 if ((type & 0x8) != 0)
937 return (-1);
938
939 /*
940 * If the expand-down bit is clear, we just check the limit as
941 * it would naturally be applied. Otherwise, we need to check
942 * that the address is the range [limit + 1 .. 0xffff] or
943 * [limit + 1 ... 0xffffffff] depending on if the default
944 * operand size bit is set.
945 */
946 if ((type & 0x4) == 0) {
947 if (*addr > limit)
948 return (-1);
949 } else if (desc->sd_def32) {
950 if (*addr < limit + 1 || 0xffff < *addr)
951 return (-1);
952 } else {
953 if (*addr < limit + 1 || 0xffffffff < *addr)
954 return (-1);
955 }
956 }
957
958 *addr += USD_GETBASE(desc);
959
960 return (0);
961 }
962
963 int
fasttrap_pid_probe(struct reg * rp)964 fasttrap_pid_probe(struct reg *rp)
965 {
966 proc_t *p = curproc;
967 #ifndef illumos
968 struct rm_priotracker tracker;
969 proc_t *pp;
970 #endif
971 uintptr_t pc = rp->r_rip - 1;
972 uintptr_t new_pc = 0;
973 fasttrap_bucket_t *bucket;
974 #ifdef illumos
975 kmutex_t *pid_mtx;
976 #endif
977 fasttrap_tracepoint_t *tp, tp_local;
978 pid_t pid;
979 dtrace_icookie_t cookie;
980 uint_t is_enabled = 0;
981
982 /*
983 * It's possible that a user (in a veritable orgy of bad planning)
984 * could redirect this thread's flow of control before it reached the
985 * return probe fasttrap. In this case we need to kill the process
986 * since it's in a unrecoverable state.
987 */
988 if (curthread->t_dtrace_step) {
989 ASSERT(curthread->t_dtrace_on);
990 fasttrap_sigtrap(p, curthread, pc);
991 return (0);
992 }
993
994 /*
995 * Clear all user tracing flags.
996 */
997 curthread->t_dtrace_ft = 0;
998 curthread->t_dtrace_pc = 0;
999 curthread->t_dtrace_npc = 0;
1000 curthread->t_dtrace_scrpc = 0;
1001 curthread->t_dtrace_astpc = 0;
1002 #ifdef __amd64
1003 curthread->t_dtrace_regv = 0;
1004 #endif
1005
1006 /*
1007 * Treat a child created by a call to vfork(2) as if it were its
1008 * parent. We know that there's only one thread of control in such a
1009 * process: this one.
1010 */
1011 #ifdef illumos
1012 while (p->p_flag & SVFORK) {
1013 p = p->p_parent;
1014 }
1015
1016 pid = p->p_pid;
1017 pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
1018 mutex_enter(pid_mtx);
1019 #else
1020 pp = p;
1021 sx_slock(&proctree_lock);
1022 while (pp->p_vmspace == pp->p_pptr->p_vmspace)
1023 pp = pp->p_pptr;
1024 pid = pp->p_pid;
1025 sx_sunlock(&proctree_lock);
1026 pp = NULL;
1027
1028 rm_rlock(&fasttrap_tp_lock, &tracker);
1029 #endif
1030
1031 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
1032
1033 /*
1034 * Lookup the tracepoint that the process just hit.
1035 */
1036 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
1037 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
1038 tp->ftt_proc->ftpc_acount != 0)
1039 break;
1040 }
1041
1042 /*
1043 * If we couldn't find a matching tracepoint, either a tracepoint has
1044 * been inserted without using the pid<pid> ioctl interface (see
1045 * fasttrap_ioctl), or somehow we have mislaid this tracepoint.
1046 */
1047 if (tp == NULL) {
1048 #ifdef illumos
1049 mutex_exit(pid_mtx);
1050 #else
1051 rm_runlock(&fasttrap_tp_lock, &tracker);
1052 #endif
1053 return (-1);
1054 }
1055
1056 /*
1057 * Set the program counter to the address of the traced instruction
1058 * so that it looks right in ustack() output.
1059 */
1060 rp->r_rip = pc;
1061
1062 if (tp->ftt_ids != NULL) {
1063 fasttrap_id_t *id;
1064
1065 #ifdef __amd64
1066 if (p->p_model == DATAMODEL_LP64) {
1067 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) {
1068 fasttrap_probe_t *probe = id->fti_probe;
1069
1070 if (id->fti_ptype == DTFTP_ENTRY) {
1071 /*
1072 * We note that this was an entry
1073 * probe to help ustack() find the
1074 * first caller.
1075 */
1076 cookie = dtrace_interrupt_disable();
1077 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY);
1078 dtrace_probe(probe->ftp_id, rp->r_rdi,
1079 rp->r_rsi, rp->r_rdx, rp->r_rcx,
1080 rp->r_r8);
1081 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY);
1082 dtrace_interrupt_enable(cookie);
1083 } else if (id->fti_ptype == DTFTP_IS_ENABLED) {
1084 /*
1085 * Note that in this case, we don't
1086 * call dtrace_probe() since it's only
1087 * an artificial probe meant to change
1088 * the flow of control so that it
1089 * encounters the true probe.
1090 */
1091 is_enabled = 1;
1092 } else if (probe->ftp_argmap == NULL) {
1093 dtrace_probe(probe->ftp_id, rp->r_rdi,
1094 rp->r_rsi, rp->r_rdx, rp->r_rcx,
1095 rp->r_r8);
1096 } else {
1097 uintptr_t t[5];
1098
1099 fasttrap_usdt_args64(probe, rp,
1100 sizeof (t) / sizeof (t[0]), t);
1101
1102 dtrace_probe(probe->ftp_id, t[0], t[1],
1103 t[2], t[3], t[4]);
1104 }
1105 }
1106 } else {
1107 #endif
1108 uintptr_t s0, s1, s2, s3, s4, s5;
1109 uint32_t *stack = (uint32_t *)rp->r_rsp;
1110
1111 /*
1112 * In 32-bit mode, all arguments are passed on the
1113 * stack. If this is a function entry probe, we need
1114 * to skip the first entry on the stack as it
1115 * represents the return address rather than a
1116 * parameter to the function.
1117 */
1118 s0 = fasttrap_fuword32_noerr(&stack[0]);
1119 s1 = fasttrap_fuword32_noerr(&stack[1]);
1120 s2 = fasttrap_fuword32_noerr(&stack[2]);
1121 s3 = fasttrap_fuword32_noerr(&stack[3]);
1122 s4 = fasttrap_fuword32_noerr(&stack[4]);
1123 s5 = fasttrap_fuword32_noerr(&stack[5]);
1124
1125 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) {
1126 fasttrap_probe_t *probe = id->fti_probe;
1127
1128 if (id->fti_ptype == DTFTP_ENTRY) {
1129 /*
1130 * We note that this was an entry
1131 * probe to help ustack() find the
1132 * first caller.
1133 */
1134 cookie = dtrace_interrupt_disable();
1135 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY);
1136 dtrace_probe(probe->ftp_id, s1, s2,
1137 s3, s4, s5);
1138 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY);
1139 dtrace_interrupt_enable(cookie);
1140 } else if (id->fti_ptype == DTFTP_IS_ENABLED) {
1141 /*
1142 * Note that in this case, we don't
1143 * call dtrace_probe() since it's only
1144 * an artificial probe meant to change
1145 * the flow of control so that it
1146 * encounters the true probe.
1147 */
1148 is_enabled = 1;
1149 } else if (probe->ftp_argmap == NULL) {
1150 dtrace_probe(probe->ftp_id, s0, s1,
1151 s2, s3, s4);
1152 } else {
1153 uint32_t t[5];
1154
1155 fasttrap_usdt_args32(probe, rp,
1156 sizeof (t) / sizeof (t[0]), t);
1157
1158 dtrace_probe(probe->ftp_id, t[0], t[1],
1159 t[2], t[3], t[4]);
1160 }
1161 }
1162 #ifdef __amd64
1163 }
1164 #endif
1165 }
1166
1167 /*
1168 * We're about to do a bunch of work so we cache a local copy of
1169 * the tracepoint to emulate the instruction, and then find the
1170 * tracepoint again later if we need to light up any return probes.
1171 */
1172 tp_local = *tp;
1173 #ifdef illumos
1174 mutex_exit(pid_mtx);
1175 #else
1176 rm_runlock(&fasttrap_tp_lock, &tracker);
1177 #endif
1178 tp = &tp_local;
1179
1180 /*
1181 * Set the program counter to appear as though the traced instruction
1182 * had completely executed. This ensures that fasttrap_getreg() will
1183 * report the expected value for REG_RIP.
1184 */
1185 rp->r_rip = pc + tp->ftt_size;
1186
1187 /*
1188 * If there's an is-enabled probe connected to this tracepoint it
1189 * means that there was a 'xorl %eax, %eax' or 'xorq %rax, %rax'
1190 * instruction that was placed there by DTrace when the binary was
1191 * linked. As this probe is, in fact, enabled, we need to stuff 1
1192 * into %eax or %rax. Accordingly, we can bypass all the instruction
1193 * emulation logic since we know the inevitable result. It's possible
1194 * that a user could construct a scenario where the 'is-enabled'
1195 * probe was on some other instruction, but that would be a rather
1196 * exotic way to shoot oneself in the foot.
1197 */
1198 if (is_enabled) {
1199 rp->r_rax = 1;
1200 new_pc = rp->r_rip;
1201 goto done;
1202 }
1203
1204 /*
1205 * We emulate certain types of instructions to ensure correctness
1206 * (in the case of position dependent instructions) or optimize
1207 * common cases. The rest we have the thread execute back in user-
1208 * land.
1209 */
1210 switch (tp->ftt_type) {
1211 case FASTTRAP_T_RET:
1212 case FASTTRAP_T_RET16:
1213 {
1214 uintptr_t dst = 0;
1215 uintptr_t addr = 0;
1216 int ret = 0;
1217
1218 /*
1219 * We have to emulate _every_ facet of the behavior of a ret
1220 * instruction including what happens if the load from %esp
1221 * fails; in that case, we send a SIGSEGV.
1222 */
1223 #ifdef __amd64
1224 if (p->p_model == DATAMODEL_NATIVE) {
1225 ret = dst = fasttrap_fulword((void *)rp->r_rsp);
1226 addr = rp->r_rsp + sizeof (uintptr_t);
1227 } else {
1228 #endif
1229 uint32_t dst32;
1230 ret = dst32 = fasttrap_fuword32((void *)rp->r_rsp);
1231 dst = dst32;
1232 addr = rp->r_rsp + sizeof (uint32_t);
1233 #ifdef __amd64
1234 }
1235 #endif
1236
1237 if (ret == -1) {
1238 fasttrap_sigsegv(p, curthread, rp->r_rsp);
1239 new_pc = pc;
1240 break;
1241 }
1242
1243 if (tp->ftt_type == FASTTRAP_T_RET16)
1244 addr += tp->ftt_dest;
1245
1246 rp->r_rsp = addr;
1247 new_pc = dst;
1248 break;
1249 }
1250
1251 case FASTTRAP_T_JCC:
1252 {
1253 uint_t taken = 0;
1254
1255 switch (tp->ftt_code) {
1256 case FASTTRAP_JO:
1257 taken = (rp->r_rflags & FASTTRAP_EFLAGS_OF) != 0;
1258 break;
1259 case FASTTRAP_JNO:
1260 taken = (rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0;
1261 break;
1262 case FASTTRAP_JB:
1263 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) != 0;
1264 break;
1265 case FASTTRAP_JAE:
1266 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) == 0;
1267 break;
1268 case FASTTRAP_JE:
1269 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0;
1270 break;
1271 case FASTTRAP_JNE:
1272 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0;
1273 break;
1274 case FASTTRAP_JBE:
1275 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) != 0 ||
1276 (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0;
1277 break;
1278 case FASTTRAP_JA:
1279 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) == 0 &&
1280 (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0;
1281 break;
1282 case FASTTRAP_JS:
1283 taken = (rp->r_rflags & FASTTRAP_EFLAGS_SF) != 0;
1284 break;
1285 case FASTTRAP_JNS:
1286 taken = (rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0;
1287 break;
1288 case FASTTRAP_JP:
1289 taken = (rp->r_rflags & FASTTRAP_EFLAGS_PF) != 0;
1290 break;
1291 case FASTTRAP_JNP:
1292 taken = (rp->r_rflags & FASTTRAP_EFLAGS_PF) == 0;
1293 break;
1294 case FASTTRAP_JL:
1295 taken = ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) !=
1296 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1297 break;
1298 case FASTTRAP_JGE:
1299 taken = ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) ==
1300 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1301 break;
1302 case FASTTRAP_JLE:
1303 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0 ||
1304 ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) !=
1305 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1306 break;
1307 case FASTTRAP_JG:
1308 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0 &&
1309 ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) ==
1310 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1311 break;
1312
1313 }
1314
1315 if (taken)
1316 new_pc = tp->ftt_dest;
1317 else
1318 new_pc = pc + tp->ftt_size;
1319 break;
1320 }
1321
1322 case FASTTRAP_T_LOOP:
1323 {
1324 uint_t taken = 0;
1325 #ifdef __amd64
1326 greg_t cx = rp->r_rcx--;
1327 #else
1328 greg_t cx = rp->r_ecx--;
1329 #endif
1330
1331 switch (tp->ftt_code) {
1332 case FASTTRAP_LOOPNZ:
1333 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0 &&
1334 cx != 0;
1335 break;
1336 case FASTTRAP_LOOPZ:
1337 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0 &&
1338 cx != 0;
1339 break;
1340 case FASTTRAP_LOOP:
1341 taken = (cx != 0);
1342 break;
1343 }
1344
1345 if (taken)
1346 new_pc = tp->ftt_dest;
1347 else
1348 new_pc = pc + tp->ftt_size;
1349 break;
1350 }
1351
1352 case FASTTRAP_T_JCXZ:
1353 {
1354 #ifdef __amd64
1355 greg_t cx = rp->r_rcx;
1356 #else
1357 greg_t cx = rp->r_ecx;
1358 #endif
1359
1360 if (cx == 0)
1361 new_pc = tp->ftt_dest;
1362 else
1363 new_pc = pc + tp->ftt_size;
1364 break;
1365 }
1366
1367 case FASTTRAP_T_PUSHL_EBP:
1368 {
1369 int ret = 0;
1370
1371 #ifdef __amd64
1372 if (p->p_model == DATAMODEL_NATIVE) {
1373 rp->r_rsp -= sizeof (uintptr_t);
1374 ret = fasttrap_sulword((void *)rp->r_rsp, rp->r_rbp);
1375 } else {
1376 #endif
1377 rp->r_rsp -= sizeof (uint32_t);
1378 ret = fasttrap_suword32((void *)rp->r_rsp, rp->r_rbp);
1379 #ifdef __amd64
1380 }
1381 #endif
1382
1383 if (ret == -1) {
1384 fasttrap_sigsegv(p, curthread, rp->r_rsp);
1385 new_pc = pc;
1386 break;
1387 }
1388
1389 new_pc = pc + tp->ftt_size;
1390 break;
1391 }
1392
1393 case FASTTRAP_T_NOP:
1394 new_pc = pc + tp->ftt_size;
1395 break;
1396
1397 case FASTTRAP_T_JMP:
1398 case FASTTRAP_T_CALL:
1399 if (tp->ftt_code == 0) {
1400 new_pc = tp->ftt_dest;
1401 } else {
1402 uintptr_t value, addr = tp->ftt_dest;
1403
1404 if (tp->ftt_base != FASTTRAP_NOREG)
1405 addr += fasttrap_getreg(rp, tp->ftt_base);
1406 if (tp->ftt_index != FASTTRAP_NOREG)
1407 addr += fasttrap_getreg(rp, tp->ftt_index) <<
1408 tp->ftt_scale;
1409
1410 if (tp->ftt_code == 1) {
1411 /*
1412 * If there's a segment prefix for this
1413 * instruction, we'll need to check permissions
1414 * and bounds on the given selector, and adjust
1415 * the address accordingly.
1416 */
1417 if (tp->ftt_segment != FASTTRAP_SEG_NONE &&
1418 fasttrap_do_seg(tp, rp, &addr) != 0) {
1419 fasttrap_sigsegv(p, curthread, addr);
1420 new_pc = pc;
1421 break;
1422 }
1423
1424 #ifdef __amd64
1425 if (p->p_model == DATAMODEL_NATIVE) {
1426 #endif
1427 if ((value = fasttrap_fulword((void *)addr))
1428 == -1) {
1429 fasttrap_sigsegv(p, curthread,
1430 addr);
1431 new_pc = pc;
1432 break;
1433 }
1434 new_pc = value;
1435 #ifdef __amd64
1436 } else {
1437 uint32_t value32;
1438 addr = (uintptr_t)(uint32_t)addr;
1439 if ((value32 = fasttrap_fuword32((void *)addr))
1440 == -1) {
1441 fasttrap_sigsegv(p, curthread,
1442 addr);
1443 new_pc = pc;
1444 break;
1445 }
1446 new_pc = value32;
1447 }
1448 #endif
1449 } else {
1450 new_pc = addr;
1451 }
1452 }
1453
1454 /*
1455 * If this is a call instruction, we need to push the return
1456 * address onto the stack. If this fails, we send the process
1457 * a SIGSEGV and reset the pc to emulate what would happen if
1458 * this instruction weren't traced.
1459 */
1460 if (tp->ftt_type == FASTTRAP_T_CALL) {
1461 int ret = 0;
1462 uintptr_t addr = 0, pcps;
1463 #ifdef __amd64
1464 if (p->p_model == DATAMODEL_NATIVE) {
1465 addr = rp->r_rsp - sizeof (uintptr_t);
1466 pcps = pc + tp->ftt_size;
1467 ret = fasttrap_sulword((void *)addr, pcps);
1468 } else {
1469 #endif
1470 addr = rp->r_rsp - sizeof (uint32_t);
1471 pcps = (uint32_t)(pc + tp->ftt_size);
1472 ret = fasttrap_suword32((void *)addr, pcps);
1473 #ifdef __amd64
1474 }
1475 #endif
1476
1477 if (ret == -1) {
1478 fasttrap_sigsegv(p, curthread, addr);
1479 new_pc = pc;
1480 break;
1481 }
1482
1483 rp->r_rsp = addr;
1484 }
1485
1486 break;
1487
1488 case FASTTRAP_T_COMMON:
1489 {
1490 uintptr_t addr;
1491 #if defined(__amd64)
1492 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 22];
1493 #else
1494 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 7];
1495 #endif
1496 uint_t i = 0;
1497 #ifdef illumos
1498 klwp_t *lwp = ttolwp(curthread);
1499
1500 /*
1501 * Compute the address of the ulwp_t and step over the
1502 * ul_self pointer. The method used to store the user-land
1503 * thread pointer is very different on 32- and 64-bit
1504 * kernels.
1505 */
1506 #if defined(__amd64)
1507 if (p->p_model == DATAMODEL_LP64) {
1508 addr = lwp->lwp_pcb.pcb_fsbase;
1509 addr += sizeof (void *);
1510 } else {
1511 addr = lwp->lwp_pcb.pcb_gsbase;
1512 addr += sizeof (caddr32_t);
1513 }
1514 #else
1515 addr = USD_GETBASE(&lwp->lwp_pcb.pcb_gsdesc);
1516 addr += sizeof (void *);
1517 #endif
1518 #else /* !illumos */
1519 fasttrap_scrspace_t *scrspace;
1520 scrspace = fasttrap_scraddr(curthread, tp->ftt_proc);
1521 if (scrspace == NULL) {
1522 /*
1523 * We failed to allocate scratch space for this thread.
1524 * Try to write the original instruction back out and
1525 * reset the pc.
1526 */
1527 if (fasttrap_copyout(tp->ftt_instr, (void *)pc,
1528 tp->ftt_size))
1529 fasttrap_sigtrap(p, curthread, pc);
1530 new_pc = pc;
1531 break;
1532 }
1533 addr = scrspace->ftss_addr;
1534 #endif /* illumos */
1535
1536 /*
1537 * Generic Instruction Tracing
1538 * ---------------------------
1539 *
1540 * This is the layout of the scratch space in the user-land
1541 * thread structure for our generated instructions.
1542 *
1543 * 32-bit mode bytes
1544 * ------------------------ -----
1545 * a: <original instruction> <= 15
1546 * jmp <pc + tp->ftt_size> 5
1547 * b: <original instruction> <= 15
1548 * int T_DTRACE_RET 2
1549 * -----
1550 * <= 37
1551 *
1552 * 64-bit mode bytes
1553 * ------------------------ -----
1554 * a: <original instruction> <= 15
1555 * jmp 0(%rip) 6
1556 * <pc + tp->ftt_size> 8
1557 * b: <original instruction> <= 15
1558 * int T_DTRACE_RET 2
1559 * -----
1560 * <= 46
1561 *
1562 * The %pc is set to a, and curthread->t_dtrace_astpc is set
1563 * to b. If we encounter a signal on the way out of the
1564 * kernel, trap() will set %pc to curthread->t_dtrace_astpc
1565 * so that we execute the original instruction and re-enter
1566 * the kernel rather than redirecting to the next instruction.
1567 *
1568 * If there are return probes (so we know that we're going to
1569 * need to reenter the kernel after executing the original
1570 * instruction), the scratch space will just contain the
1571 * original instruction followed by an interrupt -- the same
1572 * data as at b.
1573 *
1574 * %rip-relative Addressing
1575 * ------------------------
1576 *
1577 * There's a further complication in 64-bit mode due to %rip-
1578 * relative addressing. While this is clearly a beneficial
1579 * architectural decision for position independent code, it's
1580 * hard not to see it as a personal attack against the pid
1581 * provider since before there was a relatively small set of
1582 * instructions to emulate; with %rip-relative addressing,
1583 * almost every instruction can potentially depend on the
1584 * address at which it's executed. Rather than emulating
1585 * the broad spectrum of instructions that can now be
1586 * position dependent, we emulate jumps and others as in
1587 * 32-bit mode, and take a different tack for instructions
1588 * using %rip-relative addressing.
1589 *
1590 * For every instruction that uses the ModRM byte, the
1591 * in-kernel disassembler reports its location. We use the
1592 * ModRM byte to identify that an instruction uses
1593 * %rip-relative addressing and to see what other registers
1594 * the instruction uses. To emulate those instructions,
1595 * we modify the instruction to be %rax-relative rather than
1596 * %rip-relative (or %rcx-relative if the instruction uses
1597 * %rax; or %r8- or %r9-relative if the REX.B is present so
1598 * we don't have to rewrite the REX prefix). We then load
1599 * the value that %rip would have been into the scratch
1600 * register and generate an instruction to reset the scratch
1601 * register back to its original value. The instruction
1602 * sequence looks like this:
1603 *
1604 * 64-mode %rip-relative bytes
1605 * ------------------------ -----
1606 * a: <modified instruction> <= 15
1607 * movq $<value>, %<scratch> 6
1608 * jmp 0(%rip) 6
1609 * <pc + tp->ftt_size> 8
1610 * b: <modified instruction> <= 15
1611 * int T_DTRACE_RET 2
1612 * -----
1613 * 52
1614 *
1615 * We set curthread->t_dtrace_regv so that upon receiving
1616 * a signal we can reset the value of the scratch register.
1617 */
1618
1619 ASSERT(tp->ftt_size <= FASTTRAP_MAX_INSTR_SIZE);
1620
1621 curthread->t_dtrace_scrpc = addr;
1622 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
1623 i += tp->ftt_size;
1624
1625 #ifdef __amd64
1626 if (tp->ftt_ripmode != 0) {
1627 greg_t *reg = NULL;
1628
1629 ASSERT(p->p_model == DATAMODEL_LP64);
1630 ASSERT(tp->ftt_ripmode &
1631 (FASTTRAP_RIP_1 | FASTTRAP_RIP_2));
1632
1633 /*
1634 * If this was a %rip-relative instruction, we change
1635 * it to be either a %rax- or %rcx-relative
1636 * instruction (depending on whether those registers
1637 * are used as another operand; or %r8- or %r9-
1638 * relative depending on the value of REX.B). We then
1639 * set that register and generate a movq instruction
1640 * to reset the value.
1641 */
1642 if (tp->ftt_ripmode & FASTTRAP_RIP_X)
1643 scratch[i++] = FASTTRAP_REX(1, 0, 0, 1);
1644 else
1645 scratch[i++] = FASTTRAP_REX(1, 0, 0, 0);
1646
1647 if (tp->ftt_ripmode & FASTTRAP_RIP_1)
1648 scratch[i++] = FASTTRAP_MOV_EAX;
1649 else
1650 scratch[i++] = FASTTRAP_MOV_ECX;
1651
1652 switch (tp->ftt_ripmode) {
1653 case FASTTRAP_RIP_1:
1654 reg = &rp->r_rax;
1655 curthread->t_dtrace_reg = REG_RAX;
1656 break;
1657 case FASTTRAP_RIP_2:
1658 reg = &rp->r_rcx;
1659 curthread->t_dtrace_reg = REG_RCX;
1660 break;
1661 case FASTTRAP_RIP_1 | FASTTRAP_RIP_X:
1662 reg = &rp->r_r8;
1663 curthread->t_dtrace_reg = REG_R8;
1664 break;
1665 case FASTTRAP_RIP_2 | FASTTRAP_RIP_X:
1666 reg = &rp->r_r9;
1667 curthread->t_dtrace_reg = REG_R9;
1668 break;
1669 }
1670
1671 /* LINTED - alignment */
1672 *(uint64_t *)&scratch[i] = *reg;
1673 curthread->t_dtrace_regv = *reg;
1674 *reg = pc + tp->ftt_size;
1675 i += sizeof (uint64_t);
1676 }
1677 #endif
1678
1679 /*
1680 * Generate the branch instruction to what would have
1681 * normally been the subsequent instruction. In 32-bit mode,
1682 * this is just a relative branch; in 64-bit mode this is a
1683 * %rip-relative branch that loads the 64-bit pc value
1684 * immediately after the jmp instruction.
1685 */
1686 #ifdef __amd64
1687 if (p->p_model == DATAMODEL_LP64) {
1688 scratch[i++] = FASTTRAP_GROUP5_OP;
1689 scratch[i++] = FASTTRAP_MODRM(0, 4, 5);
1690 /* LINTED - alignment */
1691 *(uint32_t *)&scratch[i] = 0;
1692 i += sizeof (uint32_t);
1693 /* LINTED - alignment */
1694 *(uint64_t *)&scratch[i] = pc + tp->ftt_size;
1695 i += sizeof (uint64_t);
1696 } else {
1697 #endif
1698 /*
1699 * Set up the jmp to the next instruction; note that
1700 * the size of the traced instruction cancels out.
1701 */
1702 scratch[i++] = FASTTRAP_JMP32;
1703 /* LINTED - alignment */
1704 *(uint32_t *)&scratch[i] = pc - addr - 5;
1705 i += sizeof (uint32_t);
1706 #ifdef __amd64
1707 }
1708 #endif
1709
1710 curthread->t_dtrace_astpc = addr + i;
1711 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
1712 i += tp->ftt_size;
1713 scratch[i++] = FASTTRAP_INT;
1714 scratch[i++] = T_DTRACE_RET;
1715
1716 ASSERT(i <= sizeof (scratch));
1717
1718 #ifdef illumos
1719 if (fasttrap_copyout(scratch, (char *)addr, i)) {
1720 #else
1721 if (uwrite(p, scratch, i, addr)) {
1722 #endif
1723 fasttrap_sigtrap(p, curthread, pc);
1724 new_pc = pc;
1725 break;
1726 }
1727 if (tp->ftt_retids != NULL) {
1728 curthread->t_dtrace_step = 1;
1729 curthread->t_dtrace_ret = 1;
1730 new_pc = curthread->t_dtrace_astpc;
1731 } else {
1732 new_pc = curthread->t_dtrace_scrpc;
1733 }
1734
1735 curthread->t_dtrace_pc = pc;
1736 curthread->t_dtrace_npc = pc + tp->ftt_size;
1737 curthread->t_dtrace_on = 1;
1738 break;
1739 }
1740
1741 default:
1742 panic("fasttrap: mishandled an instruction");
1743 }
1744
1745 done:
1746 /*
1747 * If there were no return probes when we first found the tracepoint,
1748 * we should feel no obligation to honor any return probes that were
1749 * subsequently enabled -- they'll just have to wait until the next
1750 * time around.
1751 */
1752 if (tp->ftt_retids != NULL) {
1753 /*
1754 * We need to wait until the results of the instruction are
1755 * apparent before invoking any return probes. If this
1756 * instruction was emulated we can just call
1757 * fasttrap_return_common(); if it needs to be executed, we
1758 * need to wait until the user thread returns to the kernel.
1759 */
1760 if (tp->ftt_type != FASTTRAP_T_COMMON) {
1761 /*
1762 * Set the program counter to the address of the traced
1763 * instruction so that it looks right in ustack()
1764 * output. We had previously set it to the end of the
1765 * instruction to simplify %rip-relative addressing.
1766 */
1767 rp->r_rip = pc;
1768
1769 fasttrap_return_common(rp, pc, pid, new_pc);
1770 } else {
1771 ASSERT(curthread->t_dtrace_ret != 0);
1772 ASSERT(curthread->t_dtrace_pc == pc);
1773 ASSERT(curthread->t_dtrace_scrpc != 0);
1774 ASSERT(new_pc == curthread->t_dtrace_astpc);
1775 }
1776 }
1777
1778 rp->r_rip = new_pc;
1779
1780 #ifndef illumos
1781 PROC_LOCK(p);
1782 proc_write_regs(curthread, rp);
1783 PROC_UNLOCK(p);
1784 #endif
1785
1786 return (0);
1787 }
1788
1789 int
1790 fasttrap_return_probe(struct reg *rp)
1791 {
1792 proc_t *p = curproc;
1793 uintptr_t pc = curthread->t_dtrace_pc;
1794 uintptr_t npc = curthread->t_dtrace_npc;
1795
1796 curthread->t_dtrace_pc = 0;
1797 curthread->t_dtrace_npc = 0;
1798 curthread->t_dtrace_scrpc = 0;
1799 curthread->t_dtrace_astpc = 0;
1800
1801 #ifdef illumos
1802 /*
1803 * Treat a child created by a call to vfork(2) as if it were its
1804 * parent. We know that there's only one thread of control in such a
1805 * process: this one.
1806 */
1807 while (p->p_flag & SVFORK) {
1808 p = p->p_parent;
1809 }
1810 #endif
1811
1812 /*
1813 * We set rp->r_rip to the address of the traced instruction so
1814 * that it appears to dtrace_probe() that we're on the original
1815 * instruction, and so that the user can't easily detect our
1816 * complex web of lies. dtrace_return_probe() (our caller)
1817 * will correctly set %pc after we return.
1818 */
1819 rp->r_rip = pc;
1820
1821 fasttrap_return_common(rp, pc, p->p_pid, npc);
1822
1823 return (0);
1824 }
1825
1826 /*ARGSUSED*/
1827 uint64_t
1828 fasttrap_pid_getarg(void *arg, dtrace_id_t id, void *parg, int argno,
1829 int aframes)
1830 {
1831 struct reg r;
1832
1833 fill_regs(curthread, &r);
1834
1835 return (fasttrap_anarg(&r, 1, argno));
1836 }
1837
1838 /*ARGSUSED*/
1839 uint64_t
1840 fasttrap_usdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno,
1841 int aframes)
1842 {
1843 struct reg r;
1844
1845 fill_regs(curthread, &r);
1846
1847 return (fasttrap_anarg(&r, 0, argno));
1848 }
1849
1850 static ulong_t
1851 fasttrap_getreg(struct reg *rp, uint_t reg)
1852 {
1853 #ifdef __amd64
1854 switch (reg) {
1855 case REG_R15: return (rp->r_r15);
1856 case REG_R14: return (rp->r_r14);
1857 case REG_R13: return (rp->r_r13);
1858 case REG_R12: return (rp->r_r12);
1859 case REG_R11: return (rp->r_r11);
1860 case REG_R10: return (rp->r_r10);
1861 case REG_R9: return (rp->r_r9);
1862 case REG_R8: return (rp->r_r8);
1863 case REG_RDI: return (rp->r_rdi);
1864 case REG_RSI: return (rp->r_rsi);
1865 case REG_RBP: return (rp->r_rbp);
1866 case REG_RBX: return (rp->r_rbx);
1867 case REG_RDX: return (rp->r_rdx);
1868 case REG_RCX: return (rp->r_rcx);
1869 case REG_RAX: return (rp->r_rax);
1870 case REG_TRAPNO: return (rp->r_trapno);
1871 case REG_ERR: return (rp->r_err);
1872 case REG_RIP: return (rp->r_rip);
1873 case REG_CS: return (rp->r_cs);
1874 case REG_RFL: return (rp->r_rflags);
1875 case REG_RSP: return (rp->r_rsp);
1876 case REG_SS: return (rp->r_ss);
1877 case REG_FS: return (rp->r_fs);
1878 case REG_GS: return (rp->r_gs);
1879 case REG_DS: return (rp->r_ds);
1880 case REG_ES: return (rp->r_es);
1881 case REG_FSBASE: return (rdmsr(MSR_FSBASE));
1882 case REG_GSBASE: return (rdmsr(MSR_GSBASE));
1883 }
1884
1885 panic("dtrace: illegal register constant");
1886 /*NOTREACHED*/
1887 #else
1888 #define _NGREG 19
1889 if (reg >= _NGREG)
1890 panic("dtrace: illegal register constant");
1891
1892 return (((greg_t *)&rp->r_gs)[reg]);
1893 #endif
1894 }
1895