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 #include <sys/fasttrap_isa.h> 32 #include <sys/fasttrap_impl.h> 33 #include <sys/dtrace.h> 34 #include <sys/dtrace_impl.h> 35 #include <sys/cmn_err.h> 36 #include <sys/types.h> 37 #include <sys/dtrace_bsd.h> 38 #include <sys/proc.h> 39 #include <sys/reg.h> 40 #include <sys/rmlock.h> 41 #include <cddl/dev/dtrace/dtrace_cddl.h> 42 #include <cddl/dev/dtrace/x86/regset.h> 43 #include <machine/segments.h> 44 #include <machine/pcb.h> 45 #include <machine/trap.h> 46 #include <sys/sysmacros.h> 47 #include <sys/ptrace.h> 48 49 #ifdef __i386__ 50 #define r_rax r_eax 51 #define r_rbx r_ebx 52 #define r_rip r_eip 53 #define r_rflags r_eflags 54 #define r_rsp r_esp 55 #define r_rbp r_ebp 56 #endif 57 58 /* 59 * Lossless User-Land Tracing on x86 60 * --------------------------------- 61 * 62 * The execution of most instructions is not dependent on the address; for 63 * these instructions it is sufficient to copy them into the user process's 64 * address space and execute them. To effectively single-step an instruction 65 * in user-land, we copy out the following sequence of instructions to scratch 66 * space in the user thread's ulwp_t structure. 67 * 68 * We then set the program counter (%eip or %rip) to point to this scratch 69 * space. Once execution resumes, the original instruction is executed and 70 * then control flow is redirected to what was originally the subsequent 71 * instruction. If the kernel attemps to deliver a signal while single- 72 * stepping, the signal is deferred and the program counter is moved into the 73 * second sequence of instructions. The second sequence ends in a trap into 74 * the kernel where the deferred signal is then properly handled and delivered. 75 * 76 * For instructions whose execute is position dependent, we perform simple 77 * emulation. These instructions are limited to control transfer 78 * instructions in 32-bit mode, but in 64-bit mode there's the added wrinkle 79 * of %rip-relative addressing that means that almost any instruction can be 80 * position dependent. For all the details on how we emulate generic 81 * instructions included %rip-relative instructions, see the code in 82 * fasttrap_pid_probe() below where we handle instructions of type 83 * FASTTRAP_T_COMMON (under the header: Generic Instruction Tracing). 84 */ 85 86 #define FASTTRAP_MODRM_MOD(modrm) (((modrm) >> 6) & 0x3) 87 #define FASTTRAP_MODRM_REG(modrm) (((modrm) >> 3) & 0x7) 88 #define FASTTRAP_MODRM_RM(modrm) ((modrm) & 0x7) 89 #define FASTTRAP_MODRM(mod, reg, rm) (((mod) << 6) | ((reg) << 3) | (rm)) 90 91 #define FASTTRAP_SIB_SCALE(sib) (((sib) >> 6) & 0x3) 92 #define FASTTRAP_SIB_INDEX(sib) (((sib) >> 3) & 0x7) 93 #define FASTTRAP_SIB_BASE(sib) ((sib) & 0x7) 94 95 #define FASTTRAP_REX_W(rex) (((rex) >> 3) & 1) 96 #define FASTTRAP_REX_R(rex) (((rex) >> 2) & 1) 97 #define FASTTRAP_REX_X(rex) (((rex) >> 1) & 1) 98 #define FASTTRAP_REX_B(rex) ((rex) & 1) 99 #define FASTTRAP_REX(w, r, x, b) \ 100 (0x40 | ((w) << 3) | ((r) << 2) | ((x) << 1) | (b)) 101 102 /* 103 * Single-byte op-codes. 104 */ 105 #define FASTTRAP_PUSHL_EBP 0x55 106 107 #define FASTTRAP_JO 0x70 108 #define FASTTRAP_JNO 0x71 109 #define FASTTRAP_JB 0x72 110 #define FASTTRAP_JAE 0x73 111 #define FASTTRAP_JE 0x74 112 #define FASTTRAP_JNE 0x75 113 #define FASTTRAP_JBE 0x76 114 #define FASTTRAP_JA 0x77 115 #define FASTTRAP_JS 0x78 116 #define FASTTRAP_JNS 0x79 117 #define FASTTRAP_JP 0x7a 118 #define FASTTRAP_JNP 0x7b 119 #define FASTTRAP_JL 0x7c 120 #define FASTTRAP_JGE 0x7d 121 #define FASTTRAP_JLE 0x7e 122 #define FASTTRAP_JG 0x7f 123 124 #define FASTTRAP_NOP 0x90 125 126 #define FASTTRAP_MOV_EAX 0xb8 127 #define FASTTRAP_MOV_ECX 0xb9 128 129 #define FASTTRAP_RET16 0xc2 130 #define FASTTRAP_RET 0xc3 131 132 #define FASTTRAP_LOOPNZ 0xe0 133 #define FASTTRAP_LOOPZ 0xe1 134 #define FASTTRAP_LOOP 0xe2 135 #define FASTTRAP_JCXZ 0xe3 136 137 #define FASTTRAP_CALL 0xe8 138 #define FASTTRAP_JMP32 0xe9 139 #define FASTTRAP_JMP8 0xeb 140 141 #define FASTTRAP_INT3 0xcc 142 #define FASTTRAP_INT 0xcd 143 144 #define FASTTRAP_2_BYTE_OP 0x0f 145 #define FASTTRAP_GROUP5_OP 0xff 146 147 /* 148 * Two-byte op-codes (second byte only). 149 */ 150 #define FASTTRAP_0F_JO 0x80 151 #define FASTTRAP_0F_JNO 0x81 152 #define FASTTRAP_0F_JB 0x82 153 #define FASTTRAP_0F_JAE 0x83 154 #define FASTTRAP_0F_JE 0x84 155 #define FASTTRAP_0F_JNE 0x85 156 #define FASTTRAP_0F_JBE 0x86 157 #define FASTTRAP_0F_JA 0x87 158 #define FASTTRAP_0F_JS 0x88 159 #define FASTTRAP_0F_JNS 0x89 160 #define FASTTRAP_0F_JP 0x8a 161 #define FASTTRAP_0F_JNP 0x8b 162 #define FASTTRAP_0F_JL 0x8c 163 #define FASTTRAP_0F_JGE 0x8d 164 #define FASTTRAP_0F_JLE 0x8e 165 #define FASTTRAP_0F_JG 0x8f 166 167 #define FASTTRAP_EFLAGS_OF 0x800 168 #define FASTTRAP_EFLAGS_DF 0x400 169 #define FASTTRAP_EFLAGS_SF 0x080 170 #define FASTTRAP_EFLAGS_ZF 0x040 171 #define FASTTRAP_EFLAGS_AF 0x010 172 #define FASTTRAP_EFLAGS_PF 0x004 173 #define FASTTRAP_EFLAGS_CF 0x001 174 175 /* 176 * Instruction prefixes. 177 */ 178 #define FASTTRAP_PREFIX_OPERAND 0x66 179 #define FASTTRAP_PREFIX_ADDRESS 0x67 180 #define FASTTRAP_PREFIX_CS 0x2E 181 #define FASTTRAP_PREFIX_DS 0x3E 182 #define FASTTRAP_PREFIX_ES 0x26 183 #define FASTTRAP_PREFIX_FS 0x64 184 #define FASTTRAP_PREFIX_GS 0x65 185 #define FASTTRAP_PREFIX_SS 0x36 186 #define FASTTRAP_PREFIX_LOCK 0xF0 187 #define FASTTRAP_PREFIX_REP 0xF3 188 #define FASTTRAP_PREFIX_REPNE 0xF2 189 190 #define FASTTRAP_NOREG 0xff 191 192 /* 193 * Map between instruction register encodings and the kernel constants which 194 * correspond to indicies into struct regs. 195 */ 196 #ifdef __amd64 197 static const uint8_t regmap[16] = { 198 REG_RAX, REG_RCX, REG_RDX, REG_RBX, REG_RSP, REG_RBP, REG_RSI, REG_RDI, 199 REG_R8, REG_R9, REG_R10, REG_R11, REG_R12, REG_R13, REG_R14, REG_R15, 200 }; 201 #else 202 static const uint8_t regmap[8] = { 203 EAX, ECX, EDX, EBX, UESP, EBP, ESI, EDI 204 }; 205 #endif 206 207 static ulong_t fasttrap_getreg(struct reg *, uint_t); 208 209 static uint64_t 210 fasttrap_anarg(struct reg *rp, int function_entry, int argno) 211 { 212 uint64_t value = 0; 213 int shift = function_entry ? 1 : 0; 214 215 #ifdef __amd64 216 if (curproc->p_model == DATAMODEL_LP64) { 217 uintptr_t *stack; 218 219 /* 220 * In 64-bit mode, the first six arguments are stored in 221 * registers. 222 */ 223 if (argno < 6) 224 switch (argno) { 225 case 0: 226 return (rp->r_rdi); 227 case 1: 228 return (rp->r_rsi); 229 case 2: 230 return (rp->r_rdx); 231 case 3: 232 return (rp->r_rcx); 233 case 4: 234 return (rp->r_r8); 235 case 5: 236 return (rp->r_r9); 237 } 238 239 stack = (uintptr_t *)rp->r_rsp; 240 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT); 241 value = dtrace_fulword(&stack[argno - 6 + shift]); 242 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR); 243 } else { 244 #endif 245 uint32_t *stack = (uint32_t *)rp->r_rsp; 246 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT); 247 value = dtrace_fuword32(&stack[argno + shift]); 248 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR); 249 #ifdef __amd64 250 } 251 #endif 252 253 return (value); 254 } 255 256 /*ARGSUSED*/ 257 int 258 fasttrap_tracepoint_init(proc_t *p, fasttrap_tracepoint_t *tp, uintptr_t pc, 259 fasttrap_probe_type_t type) 260 { 261 uint8_t instr[FASTTRAP_MAX_INSTR_SIZE + 10]; 262 size_t len = FASTTRAP_MAX_INSTR_SIZE; 263 size_t first = MIN(len, PAGESIZE - (pc & PAGEOFFSET)); 264 uint_t start = 0; 265 int rmindex, size; 266 uint8_t seg, rex = 0; 267 268 /* 269 * Read the instruction at the given address out of the process's 270 * address space. We don't have to worry about a debugger 271 * changing this instruction before we overwrite it with our trap 272 * instruction since P_PR_LOCK is set. Since instructions can span 273 * pages, we potentially read the instruction in two parts. If the 274 * second part fails, we just zero out that part of the instruction. 275 */ 276 if (uread(p, &instr[0], first, pc) != 0) 277 return (-1); 278 if (len > first && 279 uread(p, &instr[first], len - first, pc + first) != 0) { 280 bzero(&instr[first], len - first); 281 len = first; 282 } 283 284 /* 285 * If the disassembly fails, then we have a malformed instruction. 286 */ 287 if ((size = dtrace_instr_size_isa(instr, p->p_model, &rmindex)) <= 0) 288 return (-1); 289 290 /* 291 * Make sure the disassembler isn't completely broken. 292 */ 293 ASSERT(-1 <= rmindex && rmindex < size); 294 295 /* 296 * If the computed size is greater than the number of bytes read, 297 * then it was a malformed instruction possibly because it fell on a 298 * page boundary and the subsequent page was missing or because of 299 * some malicious user. 300 */ 301 if (size > len) 302 return (-1); 303 304 tp->ftt_size = (uint8_t)size; 305 tp->ftt_segment = FASTTRAP_SEG_NONE; 306 307 /* 308 * Find the start of the instruction's opcode by processing any 309 * legacy prefixes. 310 */ 311 for (;;) { 312 seg = 0; 313 switch (instr[start]) { 314 case FASTTRAP_PREFIX_SS: 315 seg++; 316 /*FALLTHRU*/ 317 case FASTTRAP_PREFIX_GS: 318 seg++; 319 /*FALLTHRU*/ 320 case FASTTRAP_PREFIX_FS: 321 seg++; 322 /*FALLTHRU*/ 323 case FASTTRAP_PREFIX_ES: 324 seg++; 325 /*FALLTHRU*/ 326 case FASTTRAP_PREFIX_DS: 327 seg++; 328 /*FALLTHRU*/ 329 case FASTTRAP_PREFIX_CS: 330 seg++; 331 /*FALLTHRU*/ 332 case FASTTRAP_PREFIX_OPERAND: 333 case FASTTRAP_PREFIX_ADDRESS: 334 case FASTTRAP_PREFIX_LOCK: 335 case FASTTRAP_PREFIX_REP: 336 case FASTTRAP_PREFIX_REPNE: 337 if (seg != 0) { 338 /* 339 * It's illegal for an instruction to specify 340 * two segment prefixes -- give up on this 341 * illegal instruction. 342 */ 343 if (tp->ftt_segment != FASTTRAP_SEG_NONE) 344 return (-1); 345 346 tp->ftt_segment = seg; 347 } 348 start++; 349 continue; 350 } 351 break; 352 } 353 354 #ifdef __amd64 355 /* 356 * Identify the REX prefix on 64-bit processes. 357 */ 358 if (p->p_model == DATAMODEL_LP64 && (instr[start] & 0xf0) == 0x40) 359 rex = instr[start++]; 360 #endif 361 362 /* 363 * Now that we're pretty sure that the instruction is okay, copy the 364 * valid part to the tracepoint. 365 */ 366 bcopy(instr, tp->ftt_instr, FASTTRAP_MAX_INSTR_SIZE); 367 368 tp->ftt_type = FASTTRAP_T_COMMON; 369 if (instr[start] == FASTTRAP_2_BYTE_OP) { 370 switch (instr[start + 1]) { 371 case FASTTRAP_0F_JO: 372 case FASTTRAP_0F_JNO: 373 case FASTTRAP_0F_JB: 374 case FASTTRAP_0F_JAE: 375 case FASTTRAP_0F_JE: 376 case FASTTRAP_0F_JNE: 377 case FASTTRAP_0F_JBE: 378 case FASTTRAP_0F_JA: 379 case FASTTRAP_0F_JS: 380 case FASTTRAP_0F_JNS: 381 case FASTTRAP_0F_JP: 382 case FASTTRAP_0F_JNP: 383 case FASTTRAP_0F_JL: 384 case FASTTRAP_0F_JGE: 385 case FASTTRAP_0F_JLE: 386 case FASTTRAP_0F_JG: 387 tp->ftt_type = FASTTRAP_T_JCC; 388 tp->ftt_code = (instr[start + 1] & 0x0f) | FASTTRAP_JO; 389 tp->ftt_dest = pc + tp->ftt_size + 390 /* LINTED - alignment */ 391 *(int32_t *)&instr[start + 2]; 392 break; 393 } 394 } else if (instr[start] == FASTTRAP_GROUP5_OP) { 395 uint_t mod = FASTTRAP_MODRM_MOD(instr[start + 1]); 396 uint_t reg = FASTTRAP_MODRM_REG(instr[start + 1]); 397 uint_t rm = FASTTRAP_MODRM_RM(instr[start + 1]); 398 399 if (reg == 2 || reg == 4) { 400 uint_t i, sz; 401 402 if (reg == 2) 403 tp->ftt_type = FASTTRAP_T_CALL; 404 else 405 tp->ftt_type = FASTTRAP_T_JMP; 406 407 if (mod == 3) 408 tp->ftt_code = 2; 409 else 410 tp->ftt_code = 1; 411 412 ASSERT(p->p_model == DATAMODEL_LP64 || rex == 0); 413 414 /* 415 * See AMD x86-64 Architecture Programmer's Manual 416 * Volume 3, Section 1.2.7, Table 1-12, and 417 * Appendix A.3.1, Table A-15. 418 */ 419 if (mod != 3 && rm == 4) { 420 uint8_t sib = instr[start + 2]; 421 uint_t index = FASTTRAP_SIB_INDEX(sib); 422 uint_t base = FASTTRAP_SIB_BASE(sib); 423 424 tp->ftt_scale = FASTTRAP_SIB_SCALE(sib); 425 426 tp->ftt_index = (index == 4) ? 427 FASTTRAP_NOREG : 428 regmap[index | (FASTTRAP_REX_X(rex) << 3)]; 429 tp->ftt_base = (mod == 0 && base == 5) ? 430 FASTTRAP_NOREG : 431 regmap[base | (FASTTRAP_REX_B(rex) << 3)]; 432 433 i = 3; 434 sz = mod == 1 ? 1 : 4; 435 } else { 436 /* 437 * In 64-bit mode, mod == 0 and r/m == 5 438 * denotes %rip-relative addressing; in 32-bit 439 * mode, the base register isn't used. In both 440 * modes, there is a 32-bit operand. 441 */ 442 if (mod == 0 && rm == 5) { 443 #ifdef __amd64 444 if (p->p_model == DATAMODEL_LP64) 445 tp->ftt_base = REG_RIP; 446 else 447 #endif 448 tp->ftt_base = FASTTRAP_NOREG; 449 sz = 4; 450 } else { 451 uint8_t base = rm | 452 (FASTTRAP_REX_B(rex) << 3); 453 454 tp->ftt_base = regmap[base]; 455 sz = mod == 1 ? 1 : mod == 2 ? 4 : 0; 456 } 457 tp->ftt_index = FASTTRAP_NOREG; 458 i = 2; 459 } 460 461 if (sz == 1) { 462 tp->ftt_dest = *(int8_t *)&instr[start + i]; 463 } else if (sz == 4) { 464 /* LINTED - alignment */ 465 tp->ftt_dest = *(int32_t *)&instr[start + i]; 466 } else { 467 tp->ftt_dest = 0; 468 } 469 } 470 } else { 471 switch (instr[start]) { 472 case FASTTRAP_RET: 473 tp->ftt_type = FASTTRAP_T_RET; 474 break; 475 476 case FASTTRAP_RET16: 477 tp->ftt_type = FASTTRAP_T_RET16; 478 /* LINTED - alignment */ 479 tp->ftt_dest = *(uint16_t *)&instr[start + 1]; 480 break; 481 482 case FASTTRAP_JO: 483 case FASTTRAP_JNO: 484 case FASTTRAP_JB: 485 case FASTTRAP_JAE: 486 case FASTTRAP_JE: 487 case FASTTRAP_JNE: 488 case FASTTRAP_JBE: 489 case FASTTRAP_JA: 490 case FASTTRAP_JS: 491 case FASTTRAP_JNS: 492 case FASTTRAP_JP: 493 case FASTTRAP_JNP: 494 case FASTTRAP_JL: 495 case FASTTRAP_JGE: 496 case FASTTRAP_JLE: 497 case FASTTRAP_JG: 498 tp->ftt_type = FASTTRAP_T_JCC; 499 tp->ftt_code = instr[start]; 500 tp->ftt_dest = pc + tp->ftt_size + 501 (int8_t)instr[start + 1]; 502 break; 503 504 case FASTTRAP_LOOPNZ: 505 case FASTTRAP_LOOPZ: 506 case FASTTRAP_LOOP: 507 tp->ftt_type = FASTTRAP_T_LOOP; 508 tp->ftt_code = instr[start]; 509 tp->ftt_dest = pc + tp->ftt_size + 510 (int8_t)instr[start + 1]; 511 break; 512 513 case FASTTRAP_JCXZ: 514 tp->ftt_type = FASTTRAP_T_JCXZ; 515 tp->ftt_dest = pc + tp->ftt_size + 516 (int8_t)instr[start + 1]; 517 break; 518 519 case FASTTRAP_CALL: 520 tp->ftt_type = FASTTRAP_T_CALL; 521 tp->ftt_dest = pc + tp->ftt_size + 522 /* LINTED - alignment */ 523 *(int32_t *)&instr[start + 1]; 524 tp->ftt_code = 0; 525 break; 526 527 case FASTTRAP_JMP32: 528 tp->ftt_type = FASTTRAP_T_JMP; 529 tp->ftt_dest = pc + tp->ftt_size + 530 /* LINTED - alignment */ 531 *(int32_t *)&instr[start + 1]; 532 break; 533 case FASTTRAP_JMP8: 534 tp->ftt_type = FASTTRAP_T_JMP; 535 tp->ftt_dest = pc + tp->ftt_size + 536 (int8_t)instr[start + 1]; 537 break; 538 539 case FASTTRAP_PUSHL_EBP: 540 if (start == 0) 541 tp->ftt_type = FASTTRAP_T_PUSHL_EBP; 542 break; 543 544 case FASTTRAP_NOP: 545 #ifdef __amd64 546 ASSERT(p->p_model == DATAMODEL_LP64 || rex == 0); 547 548 /* 549 * On amd64 we have to be careful not to confuse a nop 550 * (actually xchgl %eax, %eax) with an instruction using 551 * the same opcode, but that does something different 552 * (e.g. xchgl %r8d, %eax or xcghq %r8, %rax). 553 */ 554 if (FASTTRAP_REX_B(rex) == 0) 555 #endif 556 tp->ftt_type = FASTTRAP_T_NOP; 557 break; 558 559 case FASTTRAP_INT3: 560 /* 561 * The pid provider shares the int3 trap with debugger 562 * breakpoints so we can't instrument them. 563 */ 564 ASSERT(instr[start] == FASTTRAP_INSTR); 565 return (-1); 566 567 case FASTTRAP_INT: 568 /* 569 * Interrupts seem like they could be traced with 570 * no negative implications, but it's possible that 571 * a thread could be redirected by the trap handling 572 * code which would eventually return to the 573 * instruction after the interrupt. If the interrupt 574 * were in our scratch space, the subsequent 575 * instruction might be overwritten before we return. 576 * Accordingly we refuse to instrument any interrupt. 577 */ 578 return (-1); 579 } 580 } 581 582 #ifdef __amd64 583 if (p->p_model == DATAMODEL_LP64 && tp->ftt_type == FASTTRAP_T_COMMON) { 584 /* 585 * If the process is 64-bit and the instruction type is still 586 * FASTTRAP_T_COMMON -- meaning we're going to copy it out an 587 * execute it -- we need to watch for %rip-relative 588 * addressing mode. See the portion of fasttrap_pid_probe() 589 * below where we handle tracepoints with type 590 * FASTTRAP_T_COMMON for how we emulate instructions that 591 * employ %rip-relative addressing. 592 */ 593 if (rmindex != -1) { 594 uint_t mod = FASTTRAP_MODRM_MOD(instr[rmindex]); 595 uint_t reg = FASTTRAP_MODRM_REG(instr[rmindex]); 596 uint_t rm = FASTTRAP_MODRM_RM(instr[rmindex]); 597 598 ASSERT(rmindex > start); 599 600 if (mod == 0 && rm == 5) { 601 /* 602 * We need to be sure to avoid other 603 * registers used by this instruction. While 604 * the reg field may determine the op code 605 * rather than denoting a register, assuming 606 * that it denotes a register is always safe. 607 * We leave the REX field intact and use 608 * whatever value's there for simplicity. 609 */ 610 if (reg != 0) { 611 tp->ftt_ripmode = FASTTRAP_RIP_1 | 612 (FASTTRAP_RIP_X * 613 FASTTRAP_REX_B(rex)); 614 rm = 0; 615 } else { 616 tp->ftt_ripmode = FASTTRAP_RIP_2 | 617 (FASTTRAP_RIP_X * 618 FASTTRAP_REX_B(rex)); 619 rm = 1; 620 } 621 622 tp->ftt_modrm = tp->ftt_instr[rmindex]; 623 tp->ftt_instr[rmindex] = 624 FASTTRAP_MODRM(2, reg, rm); 625 } 626 } 627 } 628 #endif 629 630 return (0); 631 } 632 633 int 634 fasttrap_tracepoint_install(proc_t *p, fasttrap_tracepoint_t *tp) 635 { 636 fasttrap_instr_t instr = FASTTRAP_INSTR; 637 638 if (uwrite(p, &instr, 1, tp->ftt_pc) != 0) 639 return (-1); 640 641 return (0); 642 } 643 644 int 645 fasttrap_tracepoint_remove(proc_t *p, fasttrap_tracepoint_t *tp) 646 { 647 uint8_t instr; 648 649 /* 650 * Distinguish between read or write failures and a changed 651 * instruction. 652 */ 653 if (uread(p, &instr, 1, tp->ftt_pc) != 0) 654 return (0); 655 if (instr != FASTTRAP_INSTR) 656 return (0); 657 if (uwrite(p, &tp->ftt_instr[0], 1, tp->ftt_pc) != 0) 658 return (-1); 659 660 return (0); 661 } 662 663 #ifdef __amd64 664 static uintptr_t 665 fasttrap_fulword_noerr(const void *uaddr) 666 { 667 uintptr_t ret; 668 669 if ((ret = fasttrap_fulword(uaddr)) != -1) 670 return (ret); 671 672 return (0); 673 } 674 #endif 675 676 static uint32_t 677 fasttrap_fuword32_noerr(const void *uaddr) 678 { 679 uint32_t ret; 680 681 if ((ret = fasttrap_fuword32(uaddr)) != -1) 682 return (ret); 683 684 return (0); 685 } 686 687 static void 688 fasttrap_return_common(struct reg *rp, uintptr_t pc, pid_t pid, 689 uintptr_t new_pc) 690 { 691 fasttrap_tracepoint_t *tp; 692 fasttrap_bucket_t *bucket; 693 fasttrap_id_t *id; 694 struct rm_priotracker tracker; 695 696 rm_rlock(&fasttrap_tp_lock, &tracker); 697 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)]; 698 699 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) { 700 if (pid == tp->ftt_pid && pc == tp->ftt_pc && 701 tp->ftt_proc->ftpc_acount != 0) 702 break; 703 } 704 705 /* 706 * Don't sweat it if we can't find the tracepoint again; unlike 707 * when we're in fasttrap_pid_probe(), finding the tracepoint here 708 * is not essential to the correct execution of the process. 709 */ 710 if (tp == NULL) { 711 rm_runlock(&fasttrap_tp_lock, &tracker); 712 return; 713 } 714 715 for (id = tp->ftt_retids; id != NULL; id = id->fti_next) { 716 /* 717 * If there's a branch that could act as a return site, we 718 * need to trace it, and check here if the program counter is 719 * external to the function. 720 */ 721 if (tp->ftt_type != FASTTRAP_T_RET && 722 tp->ftt_type != FASTTRAP_T_RET16 && 723 new_pc - id->fti_probe->ftp_faddr < 724 id->fti_probe->ftp_fsize) 725 continue; 726 727 dtrace_probe(id->fti_probe->ftp_id, 728 pc - id->fti_probe->ftp_faddr, 729 rp->r_rax, rp->r_rbx, 0, 0); 730 } 731 732 rm_runlock(&fasttrap_tp_lock, &tracker); 733 } 734 735 static void 736 fasttrap_sigsegv(proc_t *p, kthread_t *t, uintptr_t addr) 737 { 738 ksiginfo_t ksi; 739 740 ksiginfo_init(&ksi); 741 ksi.ksi_signo = SIGSEGV; 742 ksi.ksi_code = SEGV_MAPERR; 743 ksi.ksi_addr = (caddr_t)addr; 744 PROC_LOCK(p); 745 (void)tdksignal(t, SIGSEGV, &ksi); 746 PROC_UNLOCK(p); 747 } 748 749 #ifdef __amd64 750 static void 751 fasttrap_usdt_args64(fasttrap_probe_t *probe, struct reg *rp, int argc, 752 uintptr_t *argv) 753 { 754 int i, x, cap = MIN(argc, probe->ftp_nargs); 755 uintptr_t *stack = (uintptr_t *)rp->r_rsp; 756 757 for (i = 0; i < cap; i++) { 758 x = probe->ftp_argmap[i]; 759 760 if (x < 6) 761 argv[i] = (&rp->r_rdi)[x]; 762 else 763 argv[i] = fasttrap_fulword_noerr(&stack[x]); 764 } 765 766 for (; i < argc; i++) { 767 argv[i] = 0; 768 } 769 } 770 #endif 771 772 static void 773 fasttrap_usdt_args32(fasttrap_probe_t *probe, struct reg *rp, int argc, 774 uint32_t *argv) 775 { 776 int i, x, cap = MIN(argc, probe->ftp_nargs); 777 uint32_t *stack = (uint32_t *)rp->r_rsp; 778 779 for (i = 0; i < cap; i++) { 780 x = probe->ftp_argmap[i]; 781 782 argv[i] = fasttrap_fuword32_noerr(&stack[x]); 783 } 784 785 for (; i < argc; i++) { 786 argv[i] = 0; 787 } 788 } 789 790 static int 791 fasttrap_do_seg(fasttrap_tracepoint_t *tp, struct reg *rp, uintptr_t *addr) 792 { 793 proc_t *p = curproc; 794 #ifdef __i386__ 795 struct segment_descriptor *desc; 796 #else 797 struct user_segment_descriptor *desc; 798 #endif 799 uint16_t sel = 0, ndx, type; 800 uintptr_t limit; 801 802 switch (tp->ftt_segment) { 803 case FASTTRAP_SEG_CS: 804 sel = rp->r_cs; 805 break; 806 case FASTTRAP_SEG_DS: 807 sel = rp->r_ds; 808 break; 809 case FASTTRAP_SEG_ES: 810 sel = rp->r_es; 811 break; 812 case FASTTRAP_SEG_FS: 813 sel = rp->r_fs; 814 break; 815 case FASTTRAP_SEG_GS: 816 sel = rp->r_gs; 817 break; 818 case FASTTRAP_SEG_SS: 819 sel = rp->r_ss; 820 break; 821 } 822 823 /* 824 * Make sure the given segment register specifies a user priority 825 * selector rather than a kernel selector. 826 */ 827 if (ISPL(sel) != SEL_UPL) 828 return (-1); 829 830 ndx = IDXSEL(sel); 831 832 /* 833 * Check the bounds and grab the descriptor out of the specified 834 * descriptor table. 835 */ 836 if (ISLDT(sel)) { 837 #ifdef __i386__ 838 if (ndx > p->p_md.md_ldt->ldt_len) 839 return (-1); 840 841 desc = (struct segment_descriptor *) 842 p->p_md.md_ldt[ndx].ldt_base; 843 #else 844 if (ndx > max_ldt_segment) 845 return (-1); 846 847 desc = (struct user_segment_descriptor *) 848 p->p_md.md_ldt[ndx].ldt_base; 849 #endif 850 851 } else { 852 if (ndx >= NGDT) 853 return (-1); 854 855 #ifdef __i386__ 856 desc = &gdt[ndx].sd; 857 #else 858 desc = PCPU_PTR(gdt)[ndx]; 859 #endif 860 } 861 862 /* 863 * The descriptor must have user privilege level and it must be 864 * present in memory. 865 */ 866 if (desc->sd_dpl != SEL_UPL || desc->sd_p != 1) 867 return (-1); 868 869 type = desc->sd_type; 870 871 /* 872 * If the S bit in the type field is not set, this descriptor can 873 * only be used in system context. 874 */ 875 if ((type & 0x10) != 0x10) 876 return (-1); 877 878 limit = USD_GETLIMIT(desc) * (desc->sd_gran ? PAGESIZE : 1); 879 880 if (tp->ftt_segment == FASTTRAP_SEG_CS) { 881 /* 882 * The code/data bit and readable bit must both be set. 883 */ 884 if ((type & 0xa) != 0xa) 885 return (-1); 886 887 if (*addr > limit) 888 return (-1); 889 } else { 890 /* 891 * The code/data bit must be clear. 892 */ 893 if ((type & 0x8) != 0) 894 return (-1); 895 896 /* 897 * If the expand-down bit is clear, we just check the limit as 898 * it would naturally be applied. Otherwise, we need to check 899 * that the address is the range [limit + 1 .. 0xffff] or 900 * [limit + 1 ... 0xffffffff] depending on if the default 901 * operand size bit is set. 902 */ 903 if ((type & 0x4) == 0) { 904 if (*addr > limit) 905 return (-1); 906 } else if (desc->sd_def32) { 907 if (*addr < limit + 1 || 0xffff < *addr) 908 return (-1); 909 } else { 910 if (*addr < limit + 1 || 0xffffffff < *addr) 911 return (-1); 912 } 913 } 914 915 *addr += USD_GETBASE(desc); 916 917 return (0); 918 } 919 920 int 921 fasttrap_pid_probe(struct trapframe *tf) 922 { 923 struct reg reg, *rp; 924 proc_t *p = curproc, *pp; 925 struct rm_priotracker tracker; 926 uint64_t gen; 927 uintptr_t pc; 928 uintptr_t new_pc = 0; 929 fasttrap_bucket_t *bucket; 930 fasttrap_tracepoint_t *tp, tp_local; 931 pid_t pid; 932 dtrace_icookie_t cookie; 933 uint_t is_enabled = 0; 934 935 fill_frame_regs(tf, ®); 936 rp = ® 937 938 pc = rp->r_rip - 1; 939 940 /* 941 * It's possible that a user (in a veritable orgy of bad planning) 942 * could redirect this thread's flow of control before it reached the 943 * return probe fasttrap. In this case we need to kill the process 944 * since it's in a unrecoverable state. 945 */ 946 if (curthread->t_dtrace_step) { 947 ASSERT(curthread->t_dtrace_on); 948 fasttrap_sigtrap(p, curthread, pc); 949 return (0); 950 } 951 952 /* 953 * Clear all user tracing flags. 954 */ 955 curthread->t_dtrace_ft = 0; 956 curthread->t_dtrace_pc = 0; 957 curthread->t_dtrace_npc = 0; 958 curthread->t_dtrace_scrpc = 0; 959 curthread->t_dtrace_astpc = 0; 960 #ifdef __amd64 961 curthread->t_dtrace_regv = 0; 962 #endif 963 964 /* 965 * Treat a child created by a call to vfork(2) as if it were its 966 * parent. We know that there's only one thread of control in such a 967 * process: this one. 968 */ 969 pp = p; 970 sx_slock(&proctree_lock); 971 while (pp->p_vmspace == pp->p_pptr->p_vmspace) 972 pp = pp->p_pptr; 973 pid = pp->p_pid; 974 if (pp != p) { 975 PROC_LOCK(pp); 976 if ((pp->p_flag & P_WEXIT) != 0) { 977 /* 978 * This can happen if the child was created with 979 * rfork(2). Userspace tracing cannot work reliably in 980 * such a scenario, but we can at least try. 981 */ 982 PROC_UNLOCK(pp); 983 sx_sunlock(&proctree_lock); 984 return (-1); 985 } 986 _PHOLD_LITE(pp); 987 PROC_UNLOCK(pp); 988 } 989 sx_sunlock(&proctree_lock); 990 991 rm_rlock(&fasttrap_tp_lock, &tracker); 992 993 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)]; 994 995 /* 996 * Lookup the tracepoint that the process just hit. 997 */ 998 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) { 999 if (pid == tp->ftt_pid && pc == tp->ftt_pc && 1000 tp->ftt_proc->ftpc_acount != 0) 1001 break; 1002 } 1003 1004 /* 1005 * If we couldn't find a matching tracepoint, either a tracepoint has 1006 * been inserted without using the pid<pid> ioctl interface (see 1007 * fasttrap_ioctl), or somehow we have mislaid this tracepoint. 1008 */ 1009 if (tp == NULL) { 1010 rm_runlock(&fasttrap_tp_lock, &tracker); 1011 gen = atomic_load_acq_64(&pp->p_fasttrap_tp_gen); 1012 if (pp != p) 1013 PRELE(pp); 1014 if (curthread->t_fasttrap_tp_gen != gen) { 1015 /* 1016 * At least one tracepoint associated with this PID has 1017 * been removed from the table since #BP was raised. 1018 * Speculate that we hit a tracepoint that has since 1019 * been removed, and retry the instruction. 1020 */ 1021 curthread->t_fasttrap_tp_gen = gen; 1022 #ifdef __amd64 1023 tf->tf_rip = pc; 1024 #else 1025 tf->tf_eip = pc; 1026 #endif 1027 return (0); 1028 } 1029 return (-1); 1030 } 1031 if (pp != p) 1032 PRELE(pp); 1033 1034 /* 1035 * Set the program counter to the address of the traced instruction 1036 * so that it looks right in ustack() output. 1037 */ 1038 rp->r_rip = pc; 1039 1040 if (tp->ftt_ids != NULL) { 1041 fasttrap_id_t *id; 1042 1043 #ifdef __amd64 1044 if (p->p_model == DATAMODEL_LP64) { 1045 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) { 1046 fasttrap_probe_t *probe = id->fti_probe; 1047 1048 if (id->fti_ptype == DTFTP_ENTRY) { 1049 /* 1050 * We note that this was an entry 1051 * probe to help ustack() find the 1052 * first caller. 1053 */ 1054 cookie = dtrace_interrupt_disable(); 1055 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY); 1056 dtrace_probe(probe->ftp_id, rp->r_rdi, 1057 rp->r_rsi, rp->r_rdx, rp->r_rcx, 1058 rp->r_r8); 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, rp->r_rdi, 1072 rp->r_rsi, rp->r_rdx, rp->r_rcx, 1073 rp->r_r8); 1074 } else { 1075 uintptr_t t[5]; 1076 1077 fasttrap_usdt_args64(probe, rp, 1078 sizeof (t) / sizeof (t[0]), t); 1079 1080 dtrace_probe(probe->ftp_id, t[0], t[1], 1081 t[2], t[3], t[4]); 1082 } 1083 } 1084 } else { 1085 #endif 1086 uintptr_t s0, s1, s2, s3, s4, s5; 1087 uint32_t *stack = (uint32_t *)rp->r_rsp; 1088 1089 /* 1090 * In 32-bit mode, all arguments are passed on the 1091 * stack. If this is a function entry probe, we need 1092 * to skip the first entry on the stack as it 1093 * represents the return address rather than a 1094 * parameter to the function. 1095 */ 1096 s0 = fasttrap_fuword32_noerr(&stack[0]); 1097 s1 = fasttrap_fuword32_noerr(&stack[1]); 1098 s2 = fasttrap_fuword32_noerr(&stack[2]); 1099 s3 = fasttrap_fuword32_noerr(&stack[3]); 1100 s4 = fasttrap_fuword32_noerr(&stack[4]); 1101 s5 = fasttrap_fuword32_noerr(&stack[5]); 1102 1103 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) { 1104 fasttrap_probe_t *probe = id->fti_probe; 1105 1106 if (id->fti_ptype == DTFTP_ENTRY) { 1107 /* 1108 * We note that this was an entry 1109 * probe to help ustack() find the 1110 * first caller. 1111 */ 1112 cookie = dtrace_interrupt_disable(); 1113 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY); 1114 dtrace_probe(probe->ftp_id, s1, s2, 1115 s3, s4, s5); 1116 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY); 1117 dtrace_interrupt_enable(cookie); 1118 } else if (id->fti_ptype == DTFTP_IS_ENABLED) { 1119 /* 1120 * Note that in this case, we don't 1121 * call dtrace_probe() since it's only 1122 * an artificial probe meant to change 1123 * the flow of control so that it 1124 * encounters the true probe. 1125 */ 1126 is_enabled = 1; 1127 } else if (probe->ftp_argmap == NULL) { 1128 dtrace_probe(probe->ftp_id, s0, s1, 1129 s2, s3, s4); 1130 } else { 1131 uint32_t t[5]; 1132 1133 fasttrap_usdt_args32(probe, rp, 1134 sizeof (t) / sizeof (t[0]), t); 1135 1136 dtrace_probe(probe->ftp_id, t[0], t[1], 1137 t[2], t[3], t[4]); 1138 } 1139 } 1140 #ifdef __amd64 1141 } 1142 #endif 1143 } 1144 1145 /* 1146 * We're about to do a bunch of work so we cache a local copy of 1147 * the tracepoint to emulate the instruction, and then find the 1148 * tracepoint again later if we need to light up any return probes. 1149 */ 1150 tp_local = *tp; 1151 rm_runlock(&fasttrap_tp_lock, &tracker); 1152 tp = &tp_local; 1153 1154 /* 1155 * Set the program counter to appear as though the traced instruction 1156 * had completely executed. This ensures that fasttrap_getreg() will 1157 * report the expected value for REG_RIP. 1158 */ 1159 rp->r_rip = pc + tp->ftt_size; 1160 1161 /* 1162 * If there's an is-enabled probe connected to this tracepoint it 1163 * means that there was a 'xorl %eax, %eax' or 'xorq %rax, %rax' 1164 * instruction that was placed there by DTrace when the binary was 1165 * linked. As this probe is, in fact, enabled, we need to stuff 1 1166 * into %eax or %rax. Accordingly, we can bypass all the instruction 1167 * emulation logic since we know the inevitable result. It's possible 1168 * that a user could construct a scenario where the 'is-enabled' 1169 * probe was on some other instruction, but that would be a rather 1170 * exotic way to shoot oneself in the foot. 1171 */ 1172 if (is_enabled) { 1173 rp->r_rax = 1; 1174 new_pc = rp->r_rip; 1175 goto done; 1176 } 1177 1178 /* 1179 * We emulate certain types of instructions to ensure correctness 1180 * (in the case of position dependent instructions) or optimize 1181 * common cases. The rest we have the thread execute back in user- 1182 * land. 1183 */ 1184 switch (tp->ftt_type) { 1185 case FASTTRAP_T_RET: 1186 case FASTTRAP_T_RET16: 1187 { 1188 uintptr_t dst = 0; 1189 uintptr_t addr = 0; 1190 int ret = 0; 1191 1192 /* 1193 * We have to emulate _every_ facet of the behavior of a ret 1194 * instruction including what happens if the load from %esp 1195 * fails; in that case, we send a SIGSEGV. 1196 */ 1197 #ifdef __amd64 1198 if (p->p_model == DATAMODEL_NATIVE) { 1199 ret = dst = fasttrap_fulword((void *)rp->r_rsp); 1200 addr = rp->r_rsp + sizeof (uintptr_t); 1201 } else { 1202 #endif 1203 uint32_t dst32; 1204 ret = dst32 = fasttrap_fuword32((void *)rp->r_rsp); 1205 dst = dst32; 1206 addr = rp->r_rsp + sizeof (uint32_t); 1207 #ifdef __amd64 1208 } 1209 #endif 1210 1211 if (ret == -1) { 1212 fasttrap_sigsegv(p, curthread, rp->r_rsp); 1213 new_pc = pc; 1214 break; 1215 } 1216 1217 if (tp->ftt_type == FASTTRAP_T_RET16) 1218 addr += tp->ftt_dest; 1219 1220 rp->r_rsp = addr; 1221 new_pc = dst; 1222 break; 1223 } 1224 1225 case FASTTRAP_T_JCC: 1226 { 1227 uint_t taken = 0; 1228 1229 switch (tp->ftt_code) { 1230 case FASTTRAP_JO: 1231 taken = (rp->r_rflags & FASTTRAP_EFLAGS_OF) != 0; 1232 break; 1233 case FASTTRAP_JNO: 1234 taken = (rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0; 1235 break; 1236 case FASTTRAP_JB: 1237 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) != 0; 1238 break; 1239 case FASTTRAP_JAE: 1240 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) == 0; 1241 break; 1242 case FASTTRAP_JE: 1243 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0; 1244 break; 1245 case FASTTRAP_JNE: 1246 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0; 1247 break; 1248 case FASTTRAP_JBE: 1249 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) != 0 || 1250 (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0; 1251 break; 1252 case FASTTRAP_JA: 1253 taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) == 0 && 1254 (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0; 1255 break; 1256 case FASTTRAP_JS: 1257 taken = (rp->r_rflags & FASTTRAP_EFLAGS_SF) != 0; 1258 break; 1259 case FASTTRAP_JNS: 1260 taken = (rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0; 1261 break; 1262 case FASTTRAP_JP: 1263 taken = (rp->r_rflags & FASTTRAP_EFLAGS_PF) != 0; 1264 break; 1265 case FASTTRAP_JNP: 1266 taken = (rp->r_rflags & FASTTRAP_EFLAGS_PF) == 0; 1267 break; 1268 case FASTTRAP_JL: 1269 taken = ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) != 1270 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0); 1271 break; 1272 case FASTTRAP_JGE: 1273 taken = ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) == 1274 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0); 1275 break; 1276 case FASTTRAP_JLE: 1277 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0 || 1278 ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) != 1279 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0); 1280 break; 1281 case FASTTRAP_JG: 1282 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0 && 1283 ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) == 1284 ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0); 1285 break; 1286 1287 } 1288 1289 if (taken) 1290 new_pc = tp->ftt_dest; 1291 else 1292 new_pc = pc + tp->ftt_size; 1293 break; 1294 } 1295 1296 case FASTTRAP_T_LOOP: 1297 { 1298 uint_t taken = 0; 1299 #ifdef __amd64 1300 greg_t cx = rp->r_rcx--; 1301 #else 1302 greg_t cx = rp->r_ecx--; 1303 #endif 1304 1305 switch (tp->ftt_code) { 1306 case FASTTRAP_LOOPNZ: 1307 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0 && 1308 cx != 0; 1309 break; 1310 case FASTTRAP_LOOPZ: 1311 taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0 && 1312 cx != 0; 1313 break; 1314 case FASTTRAP_LOOP: 1315 taken = (cx != 0); 1316 break; 1317 } 1318 1319 if (taken) 1320 new_pc = tp->ftt_dest; 1321 else 1322 new_pc = pc + tp->ftt_size; 1323 break; 1324 } 1325 1326 case FASTTRAP_T_JCXZ: 1327 { 1328 #ifdef __amd64 1329 greg_t cx = rp->r_rcx; 1330 #else 1331 greg_t cx = rp->r_ecx; 1332 #endif 1333 1334 if (cx == 0) 1335 new_pc = tp->ftt_dest; 1336 else 1337 new_pc = pc + tp->ftt_size; 1338 break; 1339 } 1340 1341 case FASTTRAP_T_PUSHL_EBP: 1342 { 1343 int ret = 0; 1344 1345 #ifdef __amd64 1346 if (p->p_model == DATAMODEL_NATIVE) { 1347 rp->r_rsp -= sizeof (uintptr_t); 1348 ret = fasttrap_sulword((void *)rp->r_rsp, rp->r_rbp); 1349 } else { 1350 #endif 1351 rp->r_rsp -= sizeof (uint32_t); 1352 ret = fasttrap_suword32((void *)rp->r_rsp, rp->r_rbp); 1353 #ifdef __amd64 1354 } 1355 #endif 1356 1357 if (ret == -1) { 1358 fasttrap_sigsegv(p, curthread, rp->r_rsp); 1359 new_pc = pc; 1360 break; 1361 } 1362 1363 new_pc = pc + tp->ftt_size; 1364 break; 1365 } 1366 1367 case FASTTRAP_T_NOP: 1368 new_pc = pc + tp->ftt_size; 1369 break; 1370 1371 case FASTTRAP_T_JMP: 1372 case FASTTRAP_T_CALL: 1373 if (tp->ftt_code == 0) { 1374 new_pc = tp->ftt_dest; 1375 } else { 1376 uintptr_t value, addr = tp->ftt_dest; 1377 1378 if (tp->ftt_base != FASTTRAP_NOREG) 1379 addr += fasttrap_getreg(rp, tp->ftt_base); 1380 if (tp->ftt_index != FASTTRAP_NOREG) 1381 addr += fasttrap_getreg(rp, tp->ftt_index) << 1382 tp->ftt_scale; 1383 1384 if (tp->ftt_code == 1) { 1385 /* 1386 * If there's a segment prefix for this 1387 * instruction, we'll need to check permissions 1388 * and bounds on the given selector, and adjust 1389 * the address accordingly. 1390 */ 1391 if (tp->ftt_segment != FASTTRAP_SEG_NONE && 1392 fasttrap_do_seg(tp, rp, &addr) != 0) { 1393 fasttrap_sigsegv(p, curthread, addr); 1394 new_pc = pc; 1395 break; 1396 } 1397 1398 #ifdef __amd64 1399 if (p->p_model == DATAMODEL_NATIVE) { 1400 #endif 1401 if ((value = fasttrap_fulword((void *)addr)) 1402 == -1) { 1403 fasttrap_sigsegv(p, curthread, 1404 addr); 1405 new_pc = pc; 1406 break; 1407 } 1408 new_pc = value; 1409 #ifdef __amd64 1410 } else { 1411 uint32_t value32; 1412 addr = (uintptr_t)(uint32_t)addr; 1413 if ((value32 = fasttrap_fuword32((void *)addr)) 1414 == -1) { 1415 fasttrap_sigsegv(p, curthread, 1416 addr); 1417 new_pc = pc; 1418 break; 1419 } 1420 new_pc = value32; 1421 } 1422 #endif 1423 } else { 1424 new_pc = addr; 1425 } 1426 } 1427 1428 /* 1429 * If this is a call instruction, we need to push the return 1430 * address onto the stack. If this fails, we send the process 1431 * a SIGSEGV and reset the pc to emulate what would happen if 1432 * this instruction weren't traced. 1433 */ 1434 if (tp->ftt_type == FASTTRAP_T_CALL) { 1435 int ret = 0; 1436 uintptr_t addr = 0, pcps; 1437 #ifdef __amd64 1438 if (p->p_model == DATAMODEL_NATIVE) { 1439 addr = rp->r_rsp - sizeof (uintptr_t); 1440 pcps = pc + tp->ftt_size; 1441 ret = fasttrap_sulword((void *)addr, pcps); 1442 } else { 1443 #endif 1444 addr = rp->r_rsp - sizeof (uint32_t); 1445 pcps = (uint32_t)(pc + tp->ftt_size); 1446 ret = fasttrap_suword32((void *)addr, pcps); 1447 #ifdef __amd64 1448 } 1449 #endif 1450 1451 if (ret == -1) { 1452 fasttrap_sigsegv(p, curthread, addr); 1453 new_pc = pc; 1454 break; 1455 } 1456 1457 rp->r_rsp = addr; 1458 } 1459 1460 break; 1461 1462 case FASTTRAP_T_COMMON: 1463 { 1464 uintptr_t addr; 1465 #if defined(__amd64) 1466 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 22]; 1467 #else 1468 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 7]; 1469 #endif 1470 uint_t i = 0; 1471 fasttrap_scrspace_t *scrspace; 1472 scrspace = fasttrap_scraddr(curthread, tp->ftt_proc); 1473 if (scrspace == NULL) { 1474 /* 1475 * We failed to allocate scratch space for this thread. 1476 * Try to write the original instruction back out and 1477 * reset the pc. 1478 */ 1479 if (fasttrap_copyout(tp->ftt_instr, (void *)pc, 1480 tp->ftt_size)) 1481 fasttrap_sigtrap(p, curthread, pc); 1482 new_pc = pc; 1483 break; 1484 } 1485 addr = scrspace->ftss_addr; 1486 1487 /* 1488 * Generic Instruction Tracing 1489 * --------------------------- 1490 * 1491 * This is the layout of the scratch space in the user-land 1492 * thread structure for our generated instructions. 1493 * 1494 * 32-bit mode bytes 1495 * ------------------------ ----- 1496 * a: <original instruction> <= 15 1497 * jmp <pc + tp->ftt_size> 5 1498 * b: <original instruction> <= 15 1499 * int T_DTRACE_RET 2 1500 * ----- 1501 * <= 37 1502 * 1503 * 64-bit mode bytes 1504 * ------------------------ ----- 1505 * a: <original instruction> <= 15 1506 * jmp 0(%rip) 6 1507 * <pc + tp->ftt_size> 8 1508 * b: <original instruction> <= 15 1509 * int T_DTRACE_RET 2 1510 * ----- 1511 * <= 46 1512 * 1513 * The %pc is set to a, and curthread->t_dtrace_astpc is set 1514 * to b. If we encounter a signal on the way out of the 1515 * kernel, trap() will set %pc to curthread->t_dtrace_astpc 1516 * so that we execute the original instruction and re-enter 1517 * the kernel rather than redirecting to the next instruction. 1518 * 1519 * If there are return probes (so we know that we're going to 1520 * need to reenter the kernel after executing the original 1521 * instruction), the scratch space will just contain the 1522 * original instruction followed by an interrupt -- the same 1523 * data as at b. 1524 * 1525 * %rip-relative Addressing 1526 * ------------------------ 1527 * 1528 * There's a further complication in 64-bit mode due to %rip- 1529 * relative addressing. While this is clearly a beneficial 1530 * architectural decision for position independent code, it's 1531 * hard not to see it as a personal attack against the pid 1532 * provider since before there was a relatively small set of 1533 * instructions to emulate; with %rip-relative addressing, 1534 * almost every instruction can potentially depend on the 1535 * address at which it's executed. Rather than emulating 1536 * the broad spectrum of instructions that can now be 1537 * position dependent, we emulate jumps and others as in 1538 * 32-bit mode, and take a different tack for instructions 1539 * using %rip-relative addressing. 1540 * 1541 * For every instruction that uses the ModRM byte, the 1542 * in-kernel disassembler reports its location. We use the 1543 * ModRM byte to identify that an instruction uses 1544 * %rip-relative addressing and to see what other registers 1545 * the instruction uses. To emulate those instructions, 1546 * we modify the instruction to be %rax-relative rather than 1547 * %rip-relative (or %rcx-relative if the instruction uses 1548 * %rax; or %r8- or %r9-relative if the REX.B is present so 1549 * we don't have to rewrite the REX prefix). We then load 1550 * the value that %rip would have been into the scratch 1551 * register and generate an instruction to reset the scratch 1552 * register back to its original value. The instruction 1553 * sequence looks like this: 1554 * 1555 * 64-mode %rip-relative bytes 1556 * ------------------------ ----- 1557 * a: <modified instruction> <= 15 1558 * movq $<value>, %<scratch> 6 1559 * jmp 0(%rip) 6 1560 * <pc + tp->ftt_size> 8 1561 * b: <modified instruction> <= 15 1562 * int T_DTRACE_RET 2 1563 * ----- 1564 * 52 1565 * 1566 * We set curthread->t_dtrace_regv so that upon receiving 1567 * a signal we can reset the value of the scratch register. 1568 */ 1569 1570 ASSERT(tp->ftt_size <= FASTTRAP_MAX_INSTR_SIZE); 1571 1572 curthread->t_dtrace_scrpc = addr; 1573 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size); 1574 i += tp->ftt_size; 1575 1576 #ifdef __amd64 1577 if (tp->ftt_ripmode != 0) { 1578 greg_t *reg = NULL; 1579 1580 ASSERT(p->p_model == DATAMODEL_LP64); 1581 ASSERT(tp->ftt_ripmode & 1582 (FASTTRAP_RIP_1 | FASTTRAP_RIP_2)); 1583 1584 /* 1585 * If this was a %rip-relative instruction, we change 1586 * it to be either a %rax- or %rcx-relative 1587 * instruction (depending on whether those registers 1588 * are used as another operand; or %r8- or %r9- 1589 * relative depending on the value of REX.B). We then 1590 * set that register and generate a movq instruction 1591 * to reset the value. 1592 */ 1593 if (tp->ftt_ripmode & FASTTRAP_RIP_X) 1594 scratch[i++] = FASTTRAP_REX(1, 0, 0, 1); 1595 else 1596 scratch[i++] = FASTTRAP_REX(1, 0, 0, 0); 1597 1598 if (tp->ftt_ripmode & FASTTRAP_RIP_1) 1599 scratch[i++] = FASTTRAP_MOV_EAX; 1600 else 1601 scratch[i++] = FASTTRAP_MOV_ECX; 1602 1603 switch (tp->ftt_ripmode) { 1604 case FASTTRAP_RIP_1: 1605 reg = &rp->r_rax; 1606 curthread->t_dtrace_reg = REG_RAX; 1607 break; 1608 case FASTTRAP_RIP_2: 1609 reg = &rp->r_rcx; 1610 curthread->t_dtrace_reg = REG_RCX; 1611 break; 1612 case FASTTRAP_RIP_1 | FASTTRAP_RIP_X: 1613 reg = &rp->r_r8; 1614 curthread->t_dtrace_reg = REG_R8; 1615 break; 1616 case FASTTRAP_RIP_2 | FASTTRAP_RIP_X: 1617 reg = &rp->r_r9; 1618 curthread->t_dtrace_reg = REG_R9; 1619 break; 1620 } 1621 1622 /* LINTED - alignment */ 1623 *(uint64_t *)&scratch[i] = *reg; 1624 curthread->t_dtrace_regv = *reg; 1625 *reg = pc + tp->ftt_size; 1626 i += sizeof (uint64_t); 1627 } 1628 #endif 1629 1630 /* 1631 * Generate the branch instruction to what would have 1632 * normally been the subsequent instruction. In 32-bit mode, 1633 * this is just a relative branch; in 64-bit mode this is a 1634 * %rip-relative branch that loads the 64-bit pc value 1635 * immediately after the jmp instruction. 1636 */ 1637 #ifdef __amd64 1638 if (p->p_model == DATAMODEL_LP64) { 1639 scratch[i++] = FASTTRAP_GROUP5_OP; 1640 scratch[i++] = FASTTRAP_MODRM(0, 4, 5); 1641 /* LINTED - alignment */ 1642 *(uint32_t *)&scratch[i] = 0; 1643 i += sizeof (uint32_t); 1644 /* LINTED - alignment */ 1645 *(uint64_t *)&scratch[i] = pc + tp->ftt_size; 1646 i += sizeof (uint64_t); 1647 } else { 1648 #endif 1649 /* 1650 * Set up the jmp to the next instruction; note that 1651 * the size of the traced instruction cancels out. 1652 */ 1653 scratch[i++] = FASTTRAP_JMP32; 1654 /* LINTED - alignment */ 1655 *(uint32_t *)&scratch[i] = pc - addr - 5; 1656 i += sizeof (uint32_t); 1657 #ifdef __amd64 1658 } 1659 #endif 1660 1661 curthread->t_dtrace_astpc = addr + i; 1662 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size); 1663 i += tp->ftt_size; 1664 scratch[i++] = FASTTRAP_INT; 1665 scratch[i++] = T_DTRACE_RET; 1666 1667 ASSERT(i <= sizeof (scratch)); 1668 1669 if (uwrite(curproc, scratch, i, addr) != 0) { 1670 fasttrap_sigtrap(p, curthread, pc); 1671 new_pc = pc; 1672 break; 1673 } 1674 if (tp->ftt_retids != NULL) { 1675 curthread->t_dtrace_step = 1; 1676 curthread->t_dtrace_ret = 1; 1677 new_pc = curthread->t_dtrace_astpc; 1678 } else { 1679 new_pc = curthread->t_dtrace_scrpc; 1680 } 1681 1682 curthread->t_dtrace_pc = pc; 1683 curthread->t_dtrace_npc = pc + tp->ftt_size; 1684 curthread->t_dtrace_on = 1; 1685 break; 1686 } 1687 1688 default: 1689 panic("fasttrap: mishandled an instruction"); 1690 } 1691 1692 done: 1693 /* 1694 * If there were no return probes when we first found the tracepoint, 1695 * we should feel no obligation to honor any return probes that were 1696 * subsequently enabled -- they'll just have to wait until the next 1697 * time around. 1698 */ 1699 if (tp->ftt_retids != NULL) { 1700 /* 1701 * We need to wait until the results of the instruction are 1702 * apparent before invoking any return probes. If this 1703 * instruction was emulated we can just call 1704 * fasttrap_return_common(); if it needs to be executed, we 1705 * need to wait until the user thread returns to the kernel. 1706 */ 1707 if (tp->ftt_type != FASTTRAP_T_COMMON) { 1708 /* 1709 * Set the program counter to the address of the traced 1710 * instruction so that it looks right in ustack() 1711 * output. We had previously set it to the end of the 1712 * instruction to simplify %rip-relative addressing. 1713 */ 1714 rp->r_rip = pc; 1715 1716 fasttrap_return_common(rp, pc, pid, new_pc); 1717 } else { 1718 ASSERT(curthread->t_dtrace_ret != 0); 1719 ASSERT(curthread->t_dtrace_pc == pc); 1720 ASSERT(curthread->t_dtrace_scrpc != 0); 1721 ASSERT(new_pc == curthread->t_dtrace_astpc); 1722 } 1723 } 1724 1725 rp->r_rip = new_pc; 1726 1727 PROC_LOCK(p); 1728 proc_write_regs(curthread, rp); 1729 PROC_UNLOCK(p); 1730 1731 return (0); 1732 } 1733 1734 int 1735 fasttrap_return_probe(struct trapframe *tf) 1736 { 1737 struct reg reg, *rp; 1738 proc_t *p = curproc; 1739 uintptr_t pc = curthread->t_dtrace_pc; 1740 uintptr_t npc = curthread->t_dtrace_npc; 1741 1742 fill_frame_regs(tf, ®); 1743 rp = ® 1744 1745 curthread->t_dtrace_pc = 0; 1746 curthread->t_dtrace_npc = 0; 1747 curthread->t_dtrace_scrpc = 0; 1748 curthread->t_dtrace_astpc = 0; 1749 1750 #ifdef illumos 1751 /* 1752 * Treat a child created by a call to vfork(2) as if it were its 1753 * parent. We know that there's only one thread of control in such a 1754 * process: this one. 1755 */ 1756 while (p->p_flag & SVFORK) { 1757 p = p->p_parent; 1758 } 1759 #endif 1760 1761 /* 1762 * We set rp->r_rip to the address of the traced instruction so 1763 * that it appears to dtrace_probe() that we're on the original 1764 * instruction. 1765 */ 1766 rp->r_rip = pc; 1767 1768 fasttrap_return_common(rp, pc, p->p_pid, npc); 1769 1770 return (0); 1771 } 1772 1773 /*ARGSUSED*/ 1774 uint64_t 1775 fasttrap_pid_getarg(void *arg, dtrace_id_t id, void *parg, int argno, 1776 int aframes) 1777 { 1778 struct reg r; 1779 1780 fill_regs(curthread, &r); 1781 1782 return (fasttrap_anarg(&r, 1, argno)); 1783 } 1784 1785 /*ARGSUSED*/ 1786 uint64_t 1787 fasttrap_usdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno, 1788 int aframes) 1789 { 1790 struct reg r; 1791 1792 fill_regs(curthread, &r); 1793 1794 return (fasttrap_anarg(&r, 0, argno)); 1795 } 1796 1797 static ulong_t 1798 fasttrap_getreg(struct reg *rp, uint_t reg) 1799 { 1800 #ifdef __amd64 1801 switch (reg) { 1802 case REG_R15: return (rp->r_r15); 1803 case REG_R14: return (rp->r_r14); 1804 case REG_R13: return (rp->r_r13); 1805 case REG_R12: return (rp->r_r12); 1806 case REG_R11: return (rp->r_r11); 1807 case REG_R10: return (rp->r_r10); 1808 case REG_R9: return (rp->r_r9); 1809 case REG_R8: return (rp->r_r8); 1810 case REG_RDI: return (rp->r_rdi); 1811 case REG_RSI: return (rp->r_rsi); 1812 case REG_RBP: return (rp->r_rbp); 1813 case REG_RBX: return (rp->r_rbx); 1814 case REG_RDX: return (rp->r_rdx); 1815 case REG_RCX: return (rp->r_rcx); 1816 case REG_RAX: return (rp->r_rax); 1817 case REG_TRAPNO: return (rp->r_trapno); 1818 case REG_ERR: return (rp->r_err); 1819 case REG_RIP: return (rp->r_rip); 1820 case REG_CS: return (rp->r_cs); 1821 case REG_RFL: return (rp->r_rflags); 1822 case REG_RSP: return (rp->r_rsp); 1823 case REG_SS: return (rp->r_ss); 1824 case REG_FS: return (rp->r_fs); 1825 case REG_GS: return (rp->r_gs); 1826 case REG_DS: return (rp->r_ds); 1827 case REG_ES: return (rp->r_es); 1828 case REG_FSBASE: return (rdmsr(MSR_FSBASE)); 1829 case REG_GSBASE: return (rdmsr(MSR_GSBASE)); 1830 } 1831 1832 panic("dtrace: illegal register constant"); 1833 /*NOTREACHED*/ 1834 #else 1835 #define _NGREG 19 1836 if (reg >= _NGREG) 1837 panic("dtrace: illegal register constant"); 1838 1839 return (((greg_t *)&rp->r_gs)[reg]); 1840 #endif 1841 } 1842