sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c

   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 #if defined(sun)
  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 #if defined(sun)
  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 <cddl/dev/dtrace/dtrace_cddl.h>
  47 #include <sys/types.h>
  48 #include <sys/proc.h>
  49 #include <sys/dtrace_bsd.h>
  50 #include <cddl/dev/dtrace/x86/regset.h>
  51 #include <machine/segments.h>
  52 #include <machine/reg.h>
  53 #include <machine/pcb.h>
  54 #endif
  55 #include <sys/sysmacros.h>
  56 #if defined(sun)
  57 #include <sys/trap.h>
  58 #include <sys/archsystm.h>
  59 #else
  60 #include <sys/ptrace.h>
  61
  62 static int
  63 proc_ops(int op, proc_t *p, void *kaddr, off_t uaddr, size_t len)
  64 {
  65         struct iovec iov;
  66         struct uio uio;
  67
  68         iov.iov_base = kaddr;
  69         iov.iov_len = len;
  70         uio.uio_offset = uaddr;
  71         uio.uio_iov = &iov;
  72         uio.uio_resid = len;
  73         uio.uio_iovcnt = 1;
  74         uio.uio_segflg = UIO_SYSSPACE;
  75         uio.uio_td = curthread;
  76         uio.uio_rw = op;
  77         PHOLD(p);
  78         if (proc_rwmem(p, &uio) != 0) {
  79                 PRELE(p);
  80                 return (-1);
  81         }
  82         PRELE(p);
  83
  84         return (0);
  85 }
  86
  87 static int
  88 uread(proc_t *p, void *kaddr, size_t len, uintptr_t uaddr)
  89 {
  90
  91         return (proc_ops(UIO_READ, p, kaddr, uaddr, len));
  92 }
  93
  94 static int
  95 uwrite(proc_t *p, void *kaddr, size_t len, uintptr_t uaddr)
  96 {
  97
  98         return (proc_ops(UIO_WRITE, p, kaddr, uaddr, len));
  99 }
 100 #endif /* sun */
 101 #ifdef __i386__
 102 #define r_rax   r_eax
 103 #define r_rbx   r_ebx
 104 #define r_rip   r_eip
 105 #define r_rflags r_eflags
 106 #define r_rsp   r_esp
 107 #define r_rbp   r_ebp
 108 #endif
 109
 110 /*
 111  * Lossless User-Land Tracing on x86
 112  * ---------------------------------
 113  *
 114  * The execution of most instructions is not dependent on the address; for
 115  * these instructions it is sufficient to copy them into the user process's
 116  * address space and execute them. To effectively single-step an instruction
 117  * in user-land, we copy out the following sequence of instructions to scratch
 118  * space in the user thread's ulwp_t structure.
 119  *
 120  * We then set the program counter (%eip or %rip) to point to this scratch
 121  * space. Once execution resumes, the original instruction is executed and
 122  * then control flow is redirected to what was originally the subsequent
 123  * instruction. If the kernel attemps to deliver a signal while single-
 124  * stepping, the signal is deferred and the program counter is moved into the
 125  * second sequence of instructions. The second sequence ends in a trap into
 126  * the kernel where the deferred signal is then properly handled and delivered.
 127  *
 128  * For instructions whose execute is position dependent, we perform simple
 129  * emulation. These instructions are limited to control transfer
 130  * instructions in 32-bit mode, but in 64-bit mode there's the added wrinkle
 131  * of %rip-relative addressing that means that almost any instruction can be
 132  * position dependent. For all the details on how we emulate generic
 133  * instructions included %rip-relative instructions, see the code in
 134  * fasttrap_pid_probe() below where we handle instructions of type
 135  * FASTTRAP_T_COMMON (under the header: Generic Instruction Tracing).
 136  */
 137
 138 #define FASTTRAP_MODRM_MOD(modrm)       (((modrm) >> 6) & 0x3)
 139 #define FASTTRAP_MODRM_REG(modrm)       (((modrm) >> 3) & 0x7)
 140 #define FASTTRAP_MODRM_RM(modrm)        ((modrm) & 0x7)
 141 #define FASTTRAP_MODRM(mod, reg, rm)    (((mod) << 6) | ((reg) << 3) | (rm))
 142
 143 #define FASTTRAP_SIB_SCALE(sib)         (((sib) >> 6) & 0x3)
 144 #define FASTTRAP_SIB_INDEX(sib)         (((sib) >> 3) & 0x7)
 145 #define FASTTRAP_SIB_BASE(sib)          ((sib) & 0x7)
 146
 147 #define FASTTRAP_REX_W(rex)             (((rex) >> 3) & 1)
 148 #define FASTTRAP_REX_R(rex)             (((rex) >> 2) & 1)
 149 #define FASTTRAP_REX_X(rex)             (((rex) >> 1) & 1)
 150 #define FASTTRAP_REX_B(rex)             ((rex) & 1)
 151 #define FASTTRAP_REX(w, r, x, b)        \
 152         (0x40 | ((w) << 3) | ((r) << 2) | ((x) << 1) | (b))
 153
 154 /*
 155  * Single-byte op-codes.
 156  */
 157 #define FASTTRAP_PUSHL_EBP      0x55
 158
 159 #define FASTTRAP_JO             0x70
 160 #define FASTTRAP_JNO            0x71
 161 #define FASTTRAP_JB             0x72
 162 #define FASTTRAP_JAE            0x73
 163 #define FASTTRAP_JE             0x74
 164 #define FASTTRAP_JNE            0x75
 165 #define FASTTRAP_JBE            0x76
 166 #define FASTTRAP_JA             0x77
 167 #define FASTTRAP_JS             0x78
 168 #define FASTTRAP_JNS            0x79
 169 #define FASTTRAP_JP             0x7a
 170 #define FASTTRAP_JNP            0x7b
 171 #define FASTTRAP_JL             0x7c
 172 #define FASTTRAP_JGE            0x7d
 173 #define FASTTRAP_JLE            0x7e
 174 #define FASTTRAP_JG             0x7f
 175
 176 #define FASTTRAP_NOP            0x90
 177
 178 #define FASTTRAP_MOV_EAX        0xb8
 179 #define FASTTRAP_MOV_ECX        0xb9
 180
 181 #define FASTTRAP_RET16          0xc2
 182 #define FASTTRAP_RET            0xc3
 183
 184 #define FASTTRAP_LOOPNZ         0xe0
 185 #define FASTTRAP_LOOPZ          0xe1
 186 #define FASTTRAP_LOOP           0xe2
 187 #define FASTTRAP_JCXZ           0xe3
 188
 189 #define FASTTRAP_CALL           0xe8
 190 #define FASTTRAP_JMP32          0xe9
 191 #define FASTTRAP_JMP8           0xeb
 192
 193 #define FASTTRAP_INT3           0xcc
 194 #define FASTTRAP_INT            0xcd
 195
 196 #define FASTTRAP_2_BYTE_OP      0x0f
 197 #define FASTTRAP_GROUP5_OP      0xff
 198
 199 /*
 200  * Two-byte op-codes (second byte only).
 201  */
 202 #define FASTTRAP_0F_JO          0x80
 203 #define FASTTRAP_0F_JNO         0x81
 204 #define FASTTRAP_0F_JB          0x82
 205 #define FASTTRAP_0F_JAE         0x83
 206 #define FASTTRAP_0F_JE          0x84
 207 #define FASTTRAP_0F_JNE         0x85
 208 #define FASTTRAP_0F_JBE         0x86
 209 #define FASTTRAP_0F_JA          0x87
 210 #define FASTTRAP_0F_JS          0x88
 211 #define FASTTRAP_0F_JNS         0x89
 212 #define FASTTRAP_0F_JP          0x8a
 213 #define FASTTRAP_0F_JNP         0x8b
 214 #define FASTTRAP_0F_JL          0x8c
 215 #define FASTTRAP_0F_JGE         0x8d
 216 #define FASTTRAP_0F_JLE         0x8e
 217 #define FASTTRAP_0F_JG          0x8f
 218
 219 #define FASTTRAP_EFLAGS_OF      0x800
 220 #define FASTTRAP_EFLAGS_DF      0x400
 221 #define FASTTRAP_EFLAGS_SF      0x080
 222 #define FASTTRAP_EFLAGS_ZF      0x040
 223 #define FASTTRAP_EFLAGS_AF      0x010
 224 #define FASTTRAP_EFLAGS_PF      0x004
 225 #define FASTTRAP_EFLAGS_CF      0x001
 226
 227 /*
 228  * Instruction prefixes.
 229  */
 230 #define FASTTRAP_PREFIX_OPERAND 0x66
 231 #define FASTTRAP_PREFIX_ADDRESS 0x67
 232 #define FASTTRAP_PREFIX_CS      0x2E
 233 #define FASTTRAP_PREFIX_DS      0x3E
 234 #define FASTTRAP_PREFIX_ES      0x26
 235 #define FASTTRAP_PREFIX_FS      0x64
 236 #define FASTTRAP_PREFIX_GS      0x65
 237 #define FASTTRAP_PREFIX_SS      0x36
 238 #define FASTTRAP_PREFIX_LOCK    0xF0
 239 #define FASTTRAP_PREFIX_REP     0xF3
 240 #define FASTTRAP_PREFIX_REPNE   0xF2
 241
 242 #define FASTTRAP_NOREG  0xff
 243
 244 /*
 245  * Map between instruction register encodings and the kernel constants which
 246  * correspond to indicies into struct regs.
 247  */
 248 #ifdef __amd64
 249 static const uint8_t regmap[16] = {
 250         REG_RAX, REG_RCX, REG_RDX, REG_RBX, REG_RSP, REG_RBP, REG_RSI, REG_RDI,
 251         REG_R8, REG_R9, REG_R10, REG_R11, REG_R12, REG_R13, REG_R14, REG_R15,
 252 };
 253 #else
 254 static const uint8_t regmap[8] = {
 255         EAX, ECX, EDX, EBX, UESP, EBP, ESI, EDI
 256 };
 257 #endif
 258
 259 static ulong_t fasttrap_getreg(struct reg *, uint_t);
 260
 261 static uint64_t
 262 fasttrap_anarg(struct reg *rp, int function_entry, int argno)
 263 {
 264         uint64_t value = 0;
 265         int shift = function_entry ? 1 : 0;
 266
 267 #ifdef __amd64
 268         if (curproc->p_model == DATAMODEL_LP64) {
 269                 uintptr_t *stack;
 270
 271                 /*
 272                  * In 64-bit mode, the first six arguments are stored in
 273                  * registers.
 274                  */
 275                 if (argno < 6)
 276                         switch (argno) {
 277                         case 0:
 278                                 return (rp->r_rdi);
 279                         case 1:
 280                                 return (rp->r_rsi);
 281                         case 2:
 282                                 return (rp->r_rdx);
 283                         case 3:
 284                                 return (rp->r_rcx);
 285                         case 4:
 286                                 return (rp->r_r8);
 287                         case 5:
 288                                 return (rp->r_r9);
 289                         }
 290
 291                 stack = (uintptr_t *)rp->r_rsp;
 292                 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
 293                 value = dtrace_fulword(&stack[argno - 6 + shift]);
 294                 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR);
 295         } else {
 296 #endif
 297 #ifdef __i386
 298                 uint32_t *stack = (uint32_t *)rp->r_esp;
 299                 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
 300                 value = dtrace_fuword32(&stack[argno + shift]);
 301                 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR);
 302 #endif
 303 #ifdef __amd64
 304         }
 305 #endif
 306
 307         return (value);
 308 }
 309
 310 /*ARGSUSED*/
 311 int
 312 fasttrap_tracepoint_init(proc_t *p, fasttrap_tracepoint_t *tp, uintptr_t pc,
 313     fasttrap_probe_type_t type)
 314 {
 315         uint8_t instr[FASTTRAP_MAX_INSTR_SIZE + 10];
 316         size_t len = FASTTRAP_MAX_INSTR_SIZE;
 317         size_t first = MIN(len, PAGESIZE - (pc & PAGEOFFSET));
 318         uint_t start = 0;
 319         int rmindex, size;
 320         uint8_t seg, rex = 0;
 321
 322         /*
 323          * Read the instruction at the given address out of the process's
 324          * address space. We don't have to worry about a debugger
 325          * changing this instruction before we overwrite it with our trap
 326          * instruction since P_PR_LOCK is set. Since instructions can span
 327          * pages, we potentially read the instruction in two parts. If the
 328          * second part fails, we just zero out that part of the instruction.
 329          */
 330         if (uread(p, &instr[0], first, pc) != 0)
 331                 return (-1);
 332         if (len > first &&
 333             uread(p, &instr[first], len - first, pc + first) != 0) {
 334                 bzero(&instr[first], len - first);
 335                 len = first;
 336         }
 337
 338         /*
 339          * If the disassembly fails, then we have a malformed instruction.
 340          */
 341         if ((size = dtrace_instr_size_isa(instr, p->p_model, &rmindex)) <= 0)
 342                 return (-1);
 343
 344         /*
 345          * Make sure the disassembler isn't completely broken.
 346          */
 347         ASSERT(-1 <= rmindex && rmindex < size);
 348
 349         /*
 350          * If the computed size is greater than the number of bytes read,
 351          * then it was a malformed instruction possibly because it fell on a
 352          * page boundary and the subsequent page was missing or because of
 353          * some malicious user.
 354          */
 355         if (size > len)
 356                 return (-1);
 357
 358         tp->ftt_size = (uint8_t)size;
 359         tp->ftt_segment = FASTTRAP_SEG_NONE;
 360
 361         /*
 362          * Find the start of the instruction's opcode by processing any
 363          * legacy prefixes.
 364          */
 365         for (;;) {
 366                 seg = 0;
 367                 switch (instr[start]) {
 368                 case FASTTRAP_PREFIX_SS:
 369                         seg++;
 370                         /*FALLTHRU*/
 371                 case FASTTRAP_PREFIX_GS:
 372                         seg++;
 373                         /*FALLTHRU*/
 374                 case FASTTRAP_PREFIX_FS:
 375                         seg++;
 376                         /*FALLTHRU*/
 377                 case FASTTRAP_PREFIX_ES:
 378                         seg++;
 379                         /*FALLTHRU*/
 380                 case FASTTRAP_PREFIX_DS:
 381                         seg++;
 382                         /*FALLTHRU*/
 383                 case FASTTRAP_PREFIX_CS:
 384                         seg++;
 385                         /*FALLTHRU*/
 386                 case FASTTRAP_PREFIX_OPERAND:
 387                 case FASTTRAP_PREFIX_ADDRESS:
 388                 case FASTTRAP_PREFIX_LOCK:
 389                 case FASTTRAP_PREFIX_REP:
 390                 case FASTTRAP_PREFIX_REPNE:
 391                         if (seg != 0) {
 392                                 /*
 393                                  * It's illegal for an instruction to specify
 394                                  * two segment prefixes -- give up on this
 395                                  * illegal instruction.
 396                                  */
 397                                 if (tp->ftt_segment != FASTTRAP_SEG_NONE)
 398                                         return (-1);
 399
 400                                 tp->ftt_segment = seg;
 401                         }
 402                         start++;
 403                         continue;
 404                 }
 405                 break;
 406         }
 407
 408 #ifdef __amd64
 409         /*
 410          * Identify the REX prefix on 64-bit processes.
 411          */
 412         if (p->p_model == DATAMODEL_LP64 && (instr[start] & 0xf0) == 0x40)
 413                 rex = instr[start++];
 414 #endif
 415
 416         /*
 417          * Now that we're pretty sure that the instruction is okay, copy the
 418          * valid part to the tracepoint.
 419          */
 420         bcopy(instr, tp->ftt_instr, FASTTRAP_MAX_INSTR_SIZE);
 421
 422         tp->ftt_type = FASTTRAP_T_COMMON;
 423         if (instr[start] == FASTTRAP_2_BYTE_OP) {
 424                 switch (instr[start + 1]) {
 425                 case FASTTRAP_0F_JO:
 426                 case FASTTRAP_0F_JNO:
 427                 case FASTTRAP_0F_JB:
 428                 case FASTTRAP_0F_JAE:
 429                 case FASTTRAP_0F_JE:
 430                 case FASTTRAP_0F_JNE:
 431                 case FASTTRAP_0F_JBE:
 432                 case FASTTRAP_0F_JA:
 433                 case FASTTRAP_0F_JS:
 434                 case FASTTRAP_0F_JNS:
 435                 case FASTTRAP_0F_JP:
 436                 case FASTTRAP_0F_JNP:
 437                 case FASTTRAP_0F_JL:
 438                 case FASTTRAP_0F_JGE:
 439                 case FASTTRAP_0F_JLE:
 440                 case FASTTRAP_0F_JG:
 441                         tp->ftt_type = FASTTRAP_T_JCC;
 442                         tp->ftt_code = (instr[start + 1] & 0x0f) | FASTTRAP_JO;
 443                         tp->ftt_dest = pc + tp->ftt_size +
 444                             /* LINTED - alignment */
 445                             *(int32_t *)&instr[start + 2];
 446                         break;
 447                 }
 448         } else if (instr[start] == FASTTRAP_GROUP5_OP) {
 449                 uint_t mod = FASTTRAP_MODRM_MOD(instr[start + 1]);
 450                 uint_t reg = FASTTRAP_MODRM_REG(instr[start + 1]);
 451                 uint_t rm = FASTTRAP_MODRM_RM(instr[start + 1]);
 452
 453                 if (reg == 2 || reg == 4) {
 454                         uint_t i, sz;
 455
 456                         if (reg == 2)
 457                                 tp->ftt_type = FASTTRAP_T_CALL;
 458                         else
 459                                 tp->ftt_type = FASTTRAP_T_JMP;
 460
 461                         if (mod == 3)
 462                                 tp->ftt_code = 2;
 463                         else
 464                                 tp->ftt_code = 1;
 465
 466                         ASSERT(p->p_model == DATAMODEL_LP64 || rex == 0);
 467
 468                         /*
 469                          * See AMD x86-64 Architecture Programmer's Manual
 470                          * Volume 3, Section 1.2.7, Table 1-12, and
 471                          * Appendix A.3.1, Table A-15.
 472                          */
 473                         if (mod != 3 && rm == 4) {
 474                                 uint8_t sib = instr[start + 2];
 475                                 uint_t index = FASTTRAP_SIB_INDEX(sib);
 476                                 uint_t base = FASTTRAP_SIB_BASE(sib);
 477
 478                                 tp->ftt_scale = FASTTRAP_SIB_SCALE(sib);
 479
 480                                 tp->ftt_index = (index == 4) ?
 481                                     FASTTRAP_NOREG :
 482                                     regmap[index | (FASTTRAP_REX_X(rex) << 3)];
 483                                 tp->ftt_base = (mod == 0 && base == 5) ?
 484                                     FASTTRAP_NOREG :
 485                                     regmap[base | (FASTTRAP_REX_B(rex) << 3)];
 486
 487                                 i = 3;
 488                                 sz = mod == 1 ? 1 : 4;
 489                         } else {
 490                                 /*
 491                                  * In 64-bit mode, mod == 0 and r/m == 5
 492                                  * denotes %rip-relative addressing; in 32-bit
 493                                  * mode, the base register isn't used. In both
 494                                  * modes, there is a 32-bit operand.
 495                                  */
 496                                 if (mod == 0 && rm == 5) {
 497 #ifdef __amd64
 498                                         if (p->p_model == DATAMODEL_LP64)
 499                                                 tp->ftt_base = REG_RIP;
 500                                         else
 501 #endif
 502                                                 tp->ftt_base = FASTTRAP_NOREG;
 503                                         sz = 4;
 504                                 } else  {
 505                                         uint8_t base = rm |
 506                                             (FASTTRAP_REX_B(rex) << 3);
 507
 508                                         tp->ftt_base = regmap[base];
 509                                         sz = mod == 1 ? 1 : mod == 2 ? 4 : 0;
 510                                 }
 511                                 tp->ftt_index = FASTTRAP_NOREG;
 512                                 i = 2;
 513                         }
 514
 515                         if (sz == 1) {
 516                                 tp->ftt_dest = *(int8_t *)&instr[start + i];
 517                         } else if (sz == 4) {
 518                                 /* LINTED - alignment */
 519                                 tp->ftt_dest = *(int32_t *)&instr[start + i];
 520                         } else {
 521                                 tp->ftt_dest = 0;
 522                         }
 523                 }
 524         } else {
 525                 switch (instr[start]) {
 526                 case FASTTRAP_RET:
 527                         tp->ftt_type = FASTTRAP_T_RET;
 528                         break;
 529
 530                 case FASTTRAP_RET16:
 531                         tp->ftt_type = FASTTRAP_T_RET16;
 532                         /* LINTED - alignment */
 533                         tp->ftt_dest = *(uint16_t *)&instr[start + 1];
 534                         break;
 535
 536                 case FASTTRAP_JO:
 537                 case FASTTRAP_JNO:
 538                 case FASTTRAP_JB:
 539                 case FASTTRAP_JAE:
 540                 case FASTTRAP_JE:
 541                 case FASTTRAP_JNE:
 542                 case FASTTRAP_JBE:
 543                 case FASTTRAP_JA:
 544                 case FASTTRAP_JS:
 545                 case FASTTRAP_JNS:
 546                 case FASTTRAP_JP:
 547                 case FASTTRAP_JNP:
 548                 case FASTTRAP_JL:
 549                 case FASTTRAP_JGE:
 550                 case FASTTRAP_JLE:
 551                 case FASTTRAP_JG:
 552                         tp->ftt_type = FASTTRAP_T_JCC;
 553                         tp->ftt_code = instr[start];
 554                         tp->ftt_dest = pc + tp->ftt_size +
 555                             (int8_t)instr[start + 1];
 556                         break;
 557
 558                 case FASTTRAP_LOOPNZ:
 559                 case FASTTRAP_LOOPZ:
 560                 case FASTTRAP_LOOP:
 561                         tp->ftt_type = FASTTRAP_T_LOOP;
 562                         tp->ftt_code = instr[start];
 563                         tp->ftt_dest = pc + tp->ftt_size +
 564                             (int8_t)instr[start + 1];
 565                         break;
 566
 567                 case FASTTRAP_JCXZ:
 568                         tp->ftt_type = FASTTRAP_T_JCXZ;
 569                         tp->ftt_dest = pc + tp->ftt_size +
 570                             (int8_t)instr[start + 1];
 571                         break;
 572
 573                 case FASTTRAP_CALL:
 574                         tp->ftt_type = FASTTRAP_T_CALL;
 575                         tp->ftt_dest = pc + tp->ftt_size +
 576                             /* LINTED - alignment */
 577                             *(int32_t *)&instr[start + 1];
 578                         tp->ftt_code = 0;
 579                         break;
 580
 581                 case FASTTRAP_JMP32:
 582                         tp->ftt_type = FASTTRAP_T_JMP;
 583                         tp->ftt_dest = pc + tp->ftt_size +
 584                             /* LINTED - alignment */
 585                             *(int32_t *)&instr[start + 1];
 586                         break;
 587                 case FASTTRAP_JMP8:
 588                         tp->ftt_type = FASTTRAP_T_JMP;
 589                         tp->ftt_dest = pc + tp->ftt_size +
 590                             (int8_t)instr[start + 1];
 591                         break;
 592
 593                 case FASTTRAP_PUSHL_EBP:
 594                         if (start == 0)
 595                                 tp->ftt_type = FASTTRAP_T_PUSHL_EBP;
 596                         break;
 597
 598                 case FASTTRAP_NOP:
 599 #ifdef __amd64
 600                         ASSERT(p->p_model == DATAMODEL_LP64 || rex == 0);
 601
 602                         /*
 603                          * On amd64 we have to be careful not to confuse a nop
 604                          * (actually xchgl %eax, %eax) with an instruction using
 605                          * the same opcode, but that does something different
 606                          * (e.g. xchgl %r8d, %eax or xcghq %r8, %rax).
 607                          */
 608                         if (FASTTRAP_REX_B(rex) == 0)
 609 #endif
 610                                 tp->ftt_type = FASTTRAP_T_NOP;
 611                         break;
 612
 613                 case FASTTRAP_INT3:
 614                         /*
 615                          * The pid provider shares the int3 trap with debugger
 616                          * breakpoints so we can't instrument them.
 617                          */
 618                         ASSERT(instr[start] == FASTTRAP_INSTR);
 619                         return (-1);
 620
 621                 case FASTTRAP_INT:
 622                         /*
 623                          * Interrupts seem like they could be traced with
 624                          * no negative implications, but it's possible that
 625                          * a thread could be redirected by the trap handling
 626                          * code which would eventually return to the
 627                          * instruction after the interrupt. If the interrupt
 628                          * were in our scratch space, the subsequent
 629                          * instruction might be overwritten before we return.
 630                          * Accordingly we refuse to instrument any interrupt.
 631                          */
 632                         return (-1);
 633                 }
 634         }
 635
 636 #ifdef __amd64
 637         if (p->p_model == DATAMODEL_LP64 && tp->ftt_type == FASTTRAP_T_COMMON) {
 638                 /*
 639                  * If the process is 64-bit and the instruction type is still
 640                  * FASTTRAP_T_COMMON -- meaning we're going to copy it out an
 641                  * execute it -- we need to watch for %rip-relative
 642                  * addressing mode. See the portion of fasttrap_pid_probe()
 643                  * below where we handle tracepoints with type
 644                  * FASTTRAP_T_COMMON for how we emulate instructions that
 645                  * employ %rip-relative addressing.
 646                  */
 647                 if (rmindex != -1) {
 648                         uint_t mod = FASTTRAP_MODRM_MOD(instr[rmindex]);
 649                         uint_t reg = FASTTRAP_MODRM_REG(instr[rmindex]);
 650                         uint_t rm = FASTTRAP_MODRM_RM(instr[rmindex]);
 651
 652                         ASSERT(rmindex > start);
 653
 654                         if (mod == 0 && rm == 5) {
 655                                 /*
 656                                  * We need to be sure to avoid other
 657                                  * registers used by this instruction. While
 658                                  * the reg field may determine the op code
 659                                  * rather than denoting a register, assuming
 660                                  * that it denotes a register is always safe.
 661                                  * We leave the REX field intact and use
 662                                  * whatever value's there for simplicity.
 663                                  */
 664                                 if (reg != 0) {
 665                                         tp->ftt_ripmode = FASTTRAP_RIP_1 |
 666                                             (FASTTRAP_RIP_X *
 667                                             FASTTRAP_REX_B(rex));
 668                                         rm = 0;
 669                                 } else {
 670                                         tp->ftt_ripmode = FASTTRAP_RIP_2 |
 671                                             (FASTTRAP_RIP_X *
 672                                             FASTTRAP_REX_B(rex));
 673                                         rm = 1;
 674                                 }
 675
 676                                 tp->ftt_modrm = tp->ftt_instr[rmindex];
 677                                 tp->ftt_instr[rmindex] =
 678                                     FASTTRAP_MODRM(2, reg, rm);
 679                         }
 680                 }
 681         }
 682 #endif
 683
 684         return (0);
 685 }
 686
 687 int
 688 fasttrap_tracepoint_install(proc_t *p, fasttrap_tracepoint_t *tp)
 689 {
 690         fasttrap_instr_t instr = FASTTRAP_INSTR;
 691
 692         if (uwrite(p, &instr, 1, tp->ftt_pc) != 0)
 693                 return (-1);
 694
 695         return (0);
 696 }
 697
 698 int
 699 fasttrap_tracepoint_remove(proc_t *p, fasttrap_tracepoint_t *tp)
 700 {
 701         uint8_t instr;
 702
 703         /*
 704          * Distinguish between read or write failures and a changed
 705          * instruction.
 706          */
 707         if (uread(p, &instr, 1, tp->ftt_pc) != 0)
 708                 return (0);
 709         if (instr != FASTTRAP_INSTR)
 710                 return (0);
 711         if (uwrite(p, &tp->ftt_instr[0], 1, tp->ftt_pc) != 0)
 712                 return (-1);
 713
 714         return (0);
 715 }
 716
 717 #ifdef __amd64
 718 static uintptr_t
 719 fasttrap_fulword_noerr(const void *uaddr)
 720 {
 721         uintptr_t ret;
 722
 723         if ((ret = fasttrap_fulword(uaddr)) != -1)
 724                 return (ret);
 725
 726         return (0);
 727 }
 728 #endif
 729
 730 #ifdef __i386__
 731 static uint32_t
 732 fasttrap_fuword32_noerr(const void *uaddr)
 733 {
 734         uint32_t ret;
 735
 736         if ((ret = fasttrap_fuword32(uaddr)) != -1)
 737                 return (ret);
 738
 739         return (0);
 740 }
 741 #endif
 742
 743 static void
 744 fasttrap_return_common(struct reg *rp, uintptr_t pc, pid_t pid,
 745     uintptr_t new_pc)
 746 {
 747         fasttrap_tracepoint_t *tp;
 748         fasttrap_bucket_t *bucket;
 749         fasttrap_id_t *id;
 750 #if defined(sun)
 751         kmutex_t *pid_mtx;
 752 #endif
 753
 754 #if defined(sun)
 755         pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
 756         mutex_enter(pid_mtx);
 757 #endif
 758         bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
 759
 760         for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
 761                 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
 762                     tp->ftt_proc->ftpc_acount != 0)
 763                         break;
 764         }
 765
 766         /*
 767          * Don't sweat it if we can't find the tracepoint again; unlike
 768          * when we're in fasttrap_pid_probe(), finding the tracepoint here
 769          * is not essential to the correct execution of the process.
 770          */
 771         if (tp == NULL) {
 772 #if defined(sun)
 773                 mutex_exit(pid_mtx);
 774 #endif
 775                 return;
 776         }
 777
 778         for (id = tp->ftt_retids; id != NULL; id = id->fti_next) {
 779                 /*
 780                  * If there's a branch that could act as a return site, we
 781                  * need to trace it, and check here if the program counter is
 782                  * external to the function.
 783                  */
 784                 if (tp->ftt_type != FASTTRAP_T_RET &&
 785                     tp->ftt_type != FASTTRAP_T_RET16 &&
 786                     new_pc - id->fti_probe->ftp_faddr <
 787                     id->fti_probe->ftp_fsize)
 788                         continue;
 789
 790                 dtrace_probe(id->fti_probe->ftp_id,
 791                     pc - id->fti_probe->ftp_faddr,
 792                     rp->r_rax, rp->r_rbx, 0, 0);
 793         }
 794
 795 #if defined(sun)
 796         mutex_exit(pid_mtx);
 797 #endif
 798 }
 799
 800 static void
 801 fasttrap_sigsegv(proc_t *p, kthread_t *t, uintptr_t addr)
 802 {
 803 #if defined(sun)
 804         sigqueue_t *sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
 805
 806         sqp->sq_info.si_signo = SIGSEGV;
 807         sqp->sq_info.si_code = SEGV_MAPERR;
 808         sqp->sq_info.si_addr = (caddr_t)addr;
 809
 810         mutex_enter(&p->p_lock);
 811         sigaddqa(p, t, sqp);
 812         mutex_exit(&p->p_lock);
 813
 814         if (t != NULL)
 815                 aston(t);
 816 #else
 817         ksiginfo_t *ksi = kmem_zalloc(sizeof (ksiginfo_t), KM_SLEEP);
 818
 819         ksiginfo_init(ksi);
 820         ksi->ksi_signo = SIGSEGV;
 821         ksi->ksi_code = SEGV_MAPERR;
 822         ksi->ksi_addr = (caddr_t)addr;
 823         (void) tdksignal(t, SIGSEGV, ksi);
 824 #endif
 825 }
 826
 827 #ifdef __amd64
 828 static void
 829 fasttrap_usdt_args64(fasttrap_probe_t *probe, struct reg *rp, int argc,
 830     uintptr_t *argv)
 831 {
 832         int i, x, cap = MIN(argc, probe->ftp_nargs);
 833         uintptr_t *stack = (uintptr_t *)rp->r_rsp;
 834
 835         for (i = 0; i < cap; i++) {
 836                 x = probe->ftp_argmap[i];
 837
 838                 if (x < 6)
 839                         argv[i] = (&rp->r_rdi)[x];
 840                 else
 841                         argv[i] = fasttrap_fulword_noerr(&stack[x]);
 842         }
 843
 844         for (; i < argc; i++) {
 845                 argv[i] = 0;
 846         }
 847 }
 848 #endif
 849
 850 #ifdef __i386__
 851 static void
 852 fasttrap_usdt_args32(fasttrap_probe_t *probe, struct reg *rp, int argc,
 853     uint32_t *argv)
 854 {
 855         int i, x, cap = MIN(argc, probe->ftp_nargs);
 856         uint32_t *stack = (uint32_t *)rp->r_rsp;
 857
 858         for (i = 0; i < cap; i++) {
 859                 x = probe->ftp_argmap[i];
 860
 861                 argv[i] = fasttrap_fuword32_noerr(&stack[x]);
 862         }
 863
 864         for (; i < argc; i++) {
 865                 argv[i] = 0;
 866         }
 867 }
 868 #endif
 869
 870 static int
 871 fasttrap_do_seg(fasttrap_tracepoint_t *tp, struct reg *rp, uintptr_t *addr)
 872 {
 873         proc_t *p = curproc;
 874 #ifdef __i386__
 875         struct segment_descriptor *desc;
 876 #else
 877         struct user_segment_descriptor *desc;
 878 #endif
 879         uint16_t sel = 0, ndx, type;
 880         uintptr_t limit;
 881
 882         switch (tp->ftt_segment) {
 883         case FASTTRAP_SEG_CS:
 884                 sel = rp->r_cs;
 885                 break;
 886         case FASTTRAP_SEG_DS:
 887                 sel = rp->r_ds;
 888                 break;
 889         case FASTTRAP_SEG_ES:
 890                 sel = rp->r_es;
 891                 break;
 892         case FASTTRAP_SEG_FS:
 893                 sel = rp->r_fs;
 894                 break;
 895         case FASTTRAP_SEG_GS:
 896                 sel = rp->r_gs;
 897                 break;
 898         case FASTTRAP_SEG_SS:
 899                 sel = rp->r_ss;
 900                 break;
 901         }
 902
 903         /*
 904          * Make sure the given segment register specifies a user priority
 905          * selector rather than a kernel selector.
 906          */
 907         if (ISPL(sel) != SEL_UPL)
 908                 return (-1);
 909
 910         ndx = IDXSEL(sel);
 911
 912         /*
 913          * Check the bounds and grab the descriptor out of the specified
 914          * descriptor table.
 915          */
 916         if (ISLDT(sel)) {
 917 #ifdef __i386__
 918                 if (ndx > p->p_md.md_ldt->ldt_len)
 919                         return (-1);
 920
 921                 desc = (struct segment_descriptor *)
 922                     p->p_md.md_ldt[ndx].ldt_base;
 923 #else
 924                 if (ndx > max_ldt_segment)
 925                         return (-1);
 926
 927                 desc = (struct user_segment_descriptor *)
 928                     p->p_md.md_ldt[ndx].ldt_base;
 929 #endif
 930
 931         } else {
 932                 if (ndx >= NGDT)
 933                         return (-1);
 934
 935 #ifdef __i386__
 936                 desc = &gdt[ndx].sd;
 937 #else
 938                 desc = &gdt[ndx];
 939 #endif
 940         }
 941
 942         /*
 943          * The descriptor must have user privilege level and it must be
 944          * present in memory.
 945          */
 946         if (desc->sd_dpl != SEL_UPL || desc->sd_p != 1)
 947                 return (-1);
 948
 949         type = desc->sd_type;
 950
 951         /*
 952          * If the S bit in the type field is not set, this descriptor can
 953          * only be used in system context.
 954          */
 955         if ((type & 0x10) != 0x10)
 956                 return (-1);
 957
 958         limit = USD_GETLIMIT(desc) * (desc->sd_gran ? PAGESIZE : 1);
 959
 960         if (tp->ftt_segment == FASTTRAP_SEG_CS) {
 961                 /*
 962                  * The code/data bit and readable bit must both be set.
 963                  */
 964                 if ((type & 0xa) != 0xa)
 965                         return (-1);
 966
 967                 if (*addr > limit)
 968                         return (-1);
 969         } else {
 970                 /*
 971                  * The code/data bit must be clear.
 972                  */
 973                 if ((type & 0x8) != 0)
 974                         return (-1);
 975
 976                 /*
 977                  * If the expand-down bit is clear, we just check the limit as
 978                  * it would naturally be applied. Otherwise, we need to check
 979                  * that the address is the range [limit + 1 .. 0xffff] or
 980                  * [limit + 1 ... 0xffffffff] depending on if the default
 981                  * operand size bit is set.
 982                  */
 983                 if ((type & 0x4) == 0) {
 984                         if (*addr > limit)
 985                                 return (-1);
 986                 } else if (desc->sd_def32) {
 987                         if (*addr < limit + 1 || 0xffff < *addr)
 988                                 return (-1);
 989                 } else {
 990                         if (*addr < limit + 1 || 0xffffffff < *addr)
 991                                 return (-1);
 992                 }
 993         }
 994
 995         *addr += USD_GETBASE(desc);
 996
 997         return (0);
 998 }
 999
1000 int
1001 fasttrap_pid_probe(struct reg *rp)
1002 {
1003         proc_t *p = curproc;
1004 #if !defined(sun)
1005         proc_t *pp;
1006 #endif
1007         uintptr_t pc = rp->r_rip - 1;
1008         uintptr_t new_pc = 0;
1009         fasttrap_bucket_t *bucket;
1010 #if defined(sun)
1011         kmutex_t *pid_mtx;
1012 #endif
1013         fasttrap_tracepoint_t *tp, tp_local;
1014         pid_t pid;
1015         dtrace_icookie_t cookie;
1016         uint_t is_enabled = 0;
1017
1018         /*
1019          * It's possible that a user (in a veritable orgy of bad planning)
1020          * could redirect this thread's flow of control before it reached the
1021          * return probe fasttrap. In this case we need to kill the process
1022          * since it's in a unrecoverable state.
1023          */
1024         if (curthread->t_dtrace_step) {
1025                 ASSERT(curthread->t_dtrace_on);
1026                 fasttrap_sigtrap(p, curthread, pc);
1027                 return (0);
1028         }
1029
1030         /*
1031          * Clear all user tracing flags.
1032          */
1033         curthread->t_dtrace_ft = 0;
1034         curthread->t_dtrace_pc = 0;
1035         curthread->t_dtrace_npc = 0;
1036         curthread->t_dtrace_scrpc = 0;
1037         curthread->t_dtrace_astpc = 0;
1038 #ifdef __amd64
1039         curthread->t_dtrace_regv = 0;
1040 #endif
1041
1042         /*
1043          * Treat a child created by a call to vfork(2) as if it were its
1044          * parent. We know that there's only one thread of control in such a
1045          * process: this one.
1046          */
1047 #if defined(sun)
1048         while (p->p_flag & SVFORK) {
1049                 p = p->p_parent;
1050         }
1051
1052         pid = p->p_pid;
1053         pid_mtx = &cpu_core[CPU->cpu_id].cpuc_pid_lock;
1054         mutex_enter(pid_mtx);
1055 #else
1056         pp = p;
1057         sx_slock(&proctree_lock);
1058         while (pp->p_vmspace == pp->p_pptr->p_vmspace)
1059                 pp = pp->p_pptr;
1060         pid = pp->p_pid;
1061         sx_sunlock(&proctree_lock);
1062         pp = NULL;
1063
1064         PROC_LOCK(p);
1065         _PHOLD(p);
1066 #endif
1067
1068         bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)];
1069
1070         /*
1071          * Lookup the tracepoint that the process just hit.
1072          */
1073         for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) {
1074                 if (pid == tp->ftt_pid && pc == tp->ftt_pc &&
1075                     tp->ftt_proc->ftpc_acount != 0)
1076                         break;
1077         }
1078
1079         /*
1080          * If we couldn't find a matching tracepoint, either a tracepoint has
1081          * been inserted without using the pid<pid> ioctl interface (see
1082          * fasttrap_ioctl), or somehow we have mislaid this tracepoint.
1083          */
1084         if (tp == NULL) {
1085 #if defined(sun)
1086                 mutex_exit(pid_mtx);
1087 #else
1088                 _PRELE(p);
1089                 PROC_UNLOCK(p);
1090 #endif
1091                 return (-1);
1092         }
1093
1094         /*
1095          * Set the program counter to the address of the traced instruction
1096          * so that it looks right in ustack() output.
1097          */
1098         rp->r_rip = pc;
1099
1100         if (tp->ftt_ids != NULL) {
1101                 fasttrap_id_t *id;
1102
1103 #ifdef __amd64
1104                 if (p->p_model == DATAMODEL_LP64) {
1105                         for (id = tp->ftt_ids; id != NULL; id = id->fti_next) {
1106                                 fasttrap_probe_t *probe = id->fti_probe;
1107
1108                                 if (id->fti_ptype == DTFTP_ENTRY) {
1109                                         /*
1110                                          * We note that this was an entry
1111                                          * probe to help ustack() find the
1112                                          * first caller.
1113                                          */
1114                                         cookie = dtrace_interrupt_disable();
1115                                         DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY);
1116                                         dtrace_probe(probe->ftp_id, rp->r_rdi,
1117                                             rp->r_rsi, rp->r_rdx, rp->r_rcx,
1118                                             rp->r_r8);
1119                                         DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY);
1120                                         dtrace_interrupt_enable(cookie);
1121                                 } else if (id->fti_ptype == DTFTP_IS_ENABLED) {
1122                                         /*
1123                                          * Note that in this case, we don't
1124                                          * call dtrace_probe() since it's only
1125                                          * an artificial probe meant to change
1126                                          * the flow of control so that it
1127                                          * encounters the true probe.
1128                                          */
1129                                         is_enabled = 1;
1130                                 } else if (probe->ftp_argmap == NULL) {
1131                                         dtrace_probe(probe->ftp_id, rp->r_rdi,
1132                                             rp->r_rsi, rp->r_rdx, rp->r_rcx,
1133                                             rp->r_r8);
1134                                 } else {
1135                                         uintptr_t t[5];
1136
1137                                         fasttrap_usdt_args64(probe, rp,
1138                                             sizeof (t) / sizeof (t[0]), t);
1139
1140                                         dtrace_probe(probe->ftp_id, t[0], t[1],
1141                                             t[2], t[3], t[4]);
1142                                 }
1143                         }
1144                 } else {
1145 #else /* __amd64 */
1146                         uintptr_t s0, s1, s2, s3, s4, s5;
1147                         uint32_t *stack = (uint32_t *)rp->r_esp;
1148
1149                         /*
1150                          * In 32-bit mode, all arguments are passed on the
1151                          * stack. If this is a function entry probe, we need
1152                          * to skip the first entry on the stack as it
1153                          * represents the return address rather than a
1154                          * parameter to the function.
1155                          */
1156                         s0 = fasttrap_fuword32_noerr(&stack[0]);
1157                         s1 = fasttrap_fuword32_noerr(&stack[1]);
1158                         s2 = fasttrap_fuword32_noerr(&stack[2]);
1159                         s3 = fasttrap_fuword32_noerr(&stack[3]);
1160                         s4 = fasttrap_fuword32_noerr(&stack[4]);
1161                         s5 = fasttrap_fuword32_noerr(&stack[5]);
1162
1163                         for (id = tp->ftt_ids; id != NULL; id = id->fti_next) {
1164                                 fasttrap_probe_t *probe = id->fti_probe;
1165
1166                                 if (id->fti_ptype == DTFTP_ENTRY) {
1167                                         /*
1168                                          * We note that this was an entry
1169                                          * probe to help ustack() find the
1170                                          * first caller.
1171                                          */
1172                                         cookie = dtrace_interrupt_disable();
1173                                         DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY);
1174                                         dtrace_probe(probe->ftp_id, s1, s2,
1175                                             s3, s4, s5);
1176                                         DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY);
1177                                         dtrace_interrupt_enable(cookie);
1178                                 } else if (id->fti_ptype == DTFTP_IS_ENABLED) {
1179                                         /*
1180                                          * Note that in this case, we don't
1181                                          * call dtrace_probe() since it's only
1182                                          * an artificial probe meant to change
1183                                          * the flow of control so that it
1184                                          * encounters the true probe.
1185                                          */
1186                                         is_enabled = 1;
1187                                 } else if (probe->ftp_argmap == NULL) {
1188                                         dtrace_probe(probe->ftp_id, s0, s1,
1189                                             s2, s3, s4);
1190                                 } else {
1191                                         uint32_t t[5];
1192
1193                                         fasttrap_usdt_args32(probe, rp,
1194                                             sizeof (t) / sizeof (t[0]), t);
1195
1196                                         dtrace_probe(probe->ftp_id, t[0], t[1],
1197                                             t[2], t[3], t[4]);
1198                                 }
1199                         }
1200 #endif /* __amd64 */
1201 #ifdef __amd64
1202                 }
1203 #endif
1204         }
1205
1206         /*
1207          * We're about to do a bunch of work so we cache a local copy of
1208          * the tracepoint to emulate the instruction, and then find the
1209          * tracepoint again later if we need to light up any return probes.
1210          */
1211         tp_local = *tp;
1212 #if defined(sun)
1213         mutex_exit(pid_mtx);
1214 #else
1215         PROC_UNLOCK(p);
1216 #endif
1217         tp = &tp_local;
1218
1219         /*
1220          * Set the program counter to appear as though the traced instruction
1221          * had completely executed. This ensures that fasttrap_getreg() will
1222          * report the expected value for REG_RIP.
1223          */
1224         rp->r_rip = pc + tp->ftt_size;
1225
1226         /*
1227          * If there's an is-enabled probe connected to this tracepoint it
1228          * means that there was a 'xorl %eax, %eax' or 'xorq %rax, %rax'
1229          * instruction that was placed there by DTrace when the binary was
1230          * linked. As this probe is, in fact, enabled, we need to stuff 1
1231          * into %eax or %rax. Accordingly, we can bypass all the instruction
1232          * emulation logic since we know the inevitable result. It's possible
1233          * that a user could construct a scenario where the 'is-enabled'
1234          * probe was on some other instruction, but that would be a rather
1235          * exotic way to shoot oneself in the foot.
1236          */
1237         if (is_enabled) {
1238                 rp->r_rax = 1;
1239                 new_pc = rp->r_rip;
1240                 goto done;
1241         }
1242
1243         /*
1244          * We emulate certain types of instructions to ensure correctness
1245          * (in the case of position dependent instructions) or optimize
1246          * common cases. The rest we have the thread execute back in user-
1247          * land.
1248          */
1249         switch (tp->ftt_type) {
1250         case FASTTRAP_T_RET:
1251         case FASTTRAP_T_RET16:
1252         {
1253                 uintptr_t dst = 0;
1254                 uintptr_t addr = 0;
1255                 int ret = 0;
1256
1257                 /*
1258                  * We have to emulate _every_ facet of the behavior of a ret
1259                  * instruction including what happens if the load from %esp
1260                  * fails; in that case, we send a SIGSEGV.
1261                  */
1262 #ifdef __amd64
1263                 if (p->p_model == DATAMODEL_NATIVE) {
1264                         ret = dst = fasttrap_fulword((void *)rp->r_rsp);
1265                         addr = rp->r_rsp + sizeof (uintptr_t);
1266                 } else {
1267 #endif
1268 #ifdef __i386__
1269                         uint32_t dst32;
1270                         ret = dst32 = fasttrap_fuword32((void *)rp->r_esp);
1271                         dst = dst32;
1272                         addr = rp->r_esp + sizeof (uint32_t);
1273 #endif
1274 #ifdef __amd64
1275                 }
1276 #endif
1277
1278                 if (ret == -1) {
1279                         fasttrap_sigsegv(p, curthread, rp->r_rsp);
1280                         new_pc = pc;
1281                         break;
1282                 }
1283
1284                 if (tp->ftt_type == FASTTRAP_T_RET16)
1285                         addr += tp->ftt_dest;
1286
1287                 rp->r_rsp = addr;
1288                 new_pc = dst;
1289                 break;
1290         }
1291
1292         case FASTTRAP_T_JCC:
1293         {
1294                 uint_t taken = 0;
1295
1296                 switch (tp->ftt_code) {
1297                 case FASTTRAP_JO:
1298                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_OF) != 0;
1299                         break;
1300                 case FASTTRAP_JNO:
1301                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0;
1302                         break;
1303                 case FASTTRAP_JB:
1304                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) != 0;
1305                         break;
1306                 case FASTTRAP_JAE:
1307                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) == 0;
1308                         break;
1309                 case FASTTRAP_JE:
1310                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0;
1311                         break;
1312                 case FASTTRAP_JNE:
1313                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0;
1314                         break;
1315                 case FASTTRAP_JBE:
1316                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) != 0 ||
1317                             (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0;
1318                         break;
1319                 case FASTTRAP_JA:
1320                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_CF) == 0 &&
1321                             (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0;
1322                         break;
1323                 case FASTTRAP_JS:
1324                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_SF) != 0;
1325                         break;
1326                 case FASTTRAP_JNS:
1327                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0;
1328                         break;
1329                 case FASTTRAP_JP:
1330                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_PF) != 0;
1331                         break;
1332                 case FASTTRAP_JNP:
1333                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_PF) == 0;
1334                         break;
1335                 case FASTTRAP_JL:
1336                         taken = ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) !=
1337                             ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1338                         break;
1339                 case FASTTRAP_JGE:
1340                         taken = ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) ==
1341                             ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1342                         break;
1343                 case FASTTRAP_JLE:
1344                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0 ||
1345                             ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) !=
1346                             ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1347                         break;
1348                 case FASTTRAP_JG:
1349                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0 &&
1350                             ((rp->r_rflags & FASTTRAP_EFLAGS_SF) == 0) ==
1351                             ((rp->r_rflags & FASTTRAP_EFLAGS_OF) == 0);
1352                         break;
1353
1354                 }
1355
1356                 if (taken)
1357                         new_pc = tp->ftt_dest;
1358                 else
1359                         new_pc = pc + tp->ftt_size;
1360                 break;
1361         }
1362
1363         case FASTTRAP_T_LOOP:
1364         {
1365                 uint_t taken = 0;
1366 #ifdef __amd64
1367                 greg_t cx = rp->r_rcx--;
1368 #else
1369                 greg_t cx = rp->r_ecx--;
1370 #endif
1371
1372                 switch (tp->ftt_code) {
1373                 case FASTTRAP_LOOPNZ:
1374                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) == 0 &&
1375                             cx != 0;
1376                         break;
1377                 case FASTTRAP_LOOPZ:
1378                         taken = (rp->r_rflags & FASTTRAP_EFLAGS_ZF) != 0 &&
1379                             cx != 0;
1380                         break;
1381                 case FASTTRAP_LOOP:
1382                         taken = (cx != 0);
1383                         break;
1384                 }
1385
1386                 if (taken)
1387                         new_pc = tp->ftt_dest;
1388                 else
1389                         new_pc = pc + tp->ftt_size;
1390                 break;
1391         }
1392
1393         case FASTTRAP_T_JCXZ:
1394         {
1395 #ifdef __amd64
1396                 greg_t cx = rp->r_rcx;
1397 #else
1398                 greg_t cx = rp->r_ecx;
1399 #endif
1400
1401                 if (cx == 0)
1402                         new_pc = tp->ftt_dest;
1403                 else
1404                         new_pc = pc + tp->ftt_size;
1405                 break;
1406         }
1407
1408         case FASTTRAP_T_PUSHL_EBP:
1409         {
1410                 int ret = 0;
1411
1412 #ifdef __amd64
1413                 if (p->p_model == DATAMODEL_NATIVE) {
1414                         rp->r_rsp -= sizeof (uintptr_t);
1415                         ret = fasttrap_sulword((void *)rp->r_rsp, rp->r_rbp);
1416                 } else {
1417 #endif
1418 #ifdef __i386__
1419                         rp->r_rsp -= sizeof (uint32_t);
1420                         ret = fasttrap_suword32((void *)rp->r_rsp, rp->r_rbp);
1421 #endif
1422 #ifdef __amd64
1423                 }
1424 #endif
1425
1426                 if (ret == -1) {
1427                         fasttrap_sigsegv(p, curthread, rp->r_rsp);
1428                         new_pc = pc;
1429                         break;
1430                 }
1431
1432                 new_pc = pc + tp->ftt_size;
1433                 break;
1434         }
1435
1436         case FASTTRAP_T_NOP:
1437                 new_pc = pc + tp->ftt_size;
1438                 break;
1439
1440         case FASTTRAP_T_JMP:
1441         case FASTTRAP_T_CALL:
1442                 if (tp->ftt_code == 0) {
1443                         new_pc = tp->ftt_dest;
1444                 } else {
1445                         uintptr_t value, addr = tp->ftt_dest;
1446
1447                         if (tp->ftt_base != FASTTRAP_NOREG)
1448                                 addr += fasttrap_getreg(rp, tp->ftt_base);
1449                         if (tp->ftt_index != FASTTRAP_NOREG)
1450                                 addr += fasttrap_getreg(rp, tp->ftt_index) <<
1451                                     tp->ftt_scale;
1452
1453                         if (tp->ftt_code == 1) {
1454                                 /*
1455                                  * If there's a segment prefix for this
1456                                  * instruction, we'll need to check permissions
1457                                  * and bounds on the given selector, and adjust
1458                                  * the address accordingly.
1459                                  */
1460                                 if (tp->ftt_segment != FASTTRAP_SEG_NONE &&
1461                                     fasttrap_do_seg(tp, rp, &addr) != 0) {
1462                                         fasttrap_sigsegv(p, curthread, addr);
1463                                         new_pc = pc;
1464                                         break;
1465                                 }
1466
1467 #ifdef __amd64
1468                                 if (p->p_model == DATAMODEL_NATIVE) {
1469 #endif
1470                                         if ((value = fasttrap_fulword((void *)addr))
1471                                              == -1) {
1472                                                 fasttrap_sigsegv(p, curthread,
1473                                                     addr);
1474                                                 new_pc = pc;
1475                                                 break;
1476                                         }
1477                                         new_pc = value;
1478 #ifdef __amd64
1479                                 } else {
1480                                         uint32_t value32;
1481                                         addr = (uintptr_t)(uint32_t)addr;
1482                                         if ((value32 = fasttrap_fuword32((void *)addr))
1483                                             == -1) {
1484                                                 fasttrap_sigsegv(p, curthread,
1485                                                     addr);
1486                                                 new_pc = pc;
1487                                                 break;
1488                                         }
1489                                         new_pc = value32;
1490                                 }
1491 #endif
1492                         } else {
1493                                 new_pc = addr;
1494                         }
1495                 }
1496
1497                 /*
1498                  * If this is a call instruction, we need to push the return
1499                  * address onto the stack. If this fails, we send the process
1500                  * a SIGSEGV and reset the pc to emulate what would happen if
1501                  * this instruction weren't traced.
1502                  */
1503                 if (tp->ftt_type == FASTTRAP_T_CALL) {
1504                         int ret = 0;
1505                         uintptr_t addr = 0, pcps;
1506 #ifdef __amd64
1507                         if (p->p_model == DATAMODEL_NATIVE) {
1508                                 addr = rp->r_rsp - sizeof (uintptr_t);
1509                                 pcps = pc + tp->ftt_size;
1510                                 ret = fasttrap_sulword((void *)addr, pcps);
1511                         } else {
1512 #endif
1513                                 addr = rp->r_rsp - sizeof (uint32_t);
1514                                 pcps = (uint32_t)(pc + tp->ftt_size);
1515                                 ret = fasttrap_suword32((void *)addr, pcps);
1516 #ifdef __amd64
1517                         }
1518 #endif
1519
1520                         if (ret == -1) {
1521                                 fasttrap_sigsegv(p, curthread, addr);
1522                                 new_pc = pc;
1523                                 break;
1524                         }
1525
1526                         rp->r_rsp = addr;
1527                 }
1528
1529                 break;
1530
1531         case FASTTRAP_T_COMMON:
1532         {
1533                 uintptr_t addr;
1534 #if defined(__amd64)
1535                 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 22];
1536 #else
1537                 uint8_t scratch[2 * FASTTRAP_MAX_INSTR_SIZE + 7];
1538 #endif
1539                 uint_t i = 0;
1540 #if defined(sun)
1541                 klwp_t *lwp = ttolwp(curthread);
1542
1543                 /*
1544                  * Compute the address of the ulwp_t and step over the
1545                  * ul_self pointer. The method used to store the user-land
1546                  * thread pointer is very different on 32- and 64-bit
1547                  * kernels.
1548                  */
1549 #if defined(__amd64)
1550                 if (p->p_model == DATAMODEL_LP64) {
1551                         addr = lwp->lwp_pcb.pcb_fsbase;
1552                         addr += sizeof (void *);
1553                 } else {
1554                         addr = lwp->lwp_pcb.pcb_gsbase;
1555                         addr += sizeof (caddr32_t);
1556                 }
1557 #else
1558                 addr = USD_GETBASE(&lwp->lwp_pcb.pcb_gsdesc);
1559                 addr += sizeof (void *);
1560 #endif
1561 #else
1562                 fasttrap_scrspace_t *scrspace;
1563                 scrspace = fasttrap_scraddr(curthread, tp->ftt_proc);
1564                 if (scrspace == NULL) {
1565                         /*
1566                          * We failed to allocate scratch space for this thread.
1567                          * Try to write the original instruction back out and
1568                          * reset the pc.
1569                          */
1570                         if (fasttrap_copyout(tp->ftt_instr, (void *)pc,
1571                             tp->ftt_size))
1572                                 fasttrap_sigtrap(p, curthread, pc);
1573                         new_pc = pc;
1574                         break;
1575                 }
1576                 addr = scrspace->ftss_addr;
1577 #endif /* sun */
1578
1579                 /*
1580                  * Generic Instruction Tracing
1581                  * ---------------------------
1582                  *
1583                  * This is the layout of the scratch space in the user-land
1584                  * thread structure for our generated instructions.
1585                  *
1586                  *      32-bit mode                     bytes
1587                  *      ------------------------        -----
1588                  * a:   <original instruction>          <= 15
1589                  *      jmp     <pc + tp->ftt_size>         5
1590                  * b:   <original instruction>          <= 15
1591                  *      int     T_DTRACE_RET                2
1592                  *                                      -----
1593                  *                                      <= 37
1594                  *
1595                  *      64-bit mode                     bytes
1596                  *      ------------------------        -----
1597                  * a:   <original instruction>          <= 15
1598                  *      jmp     0(%rip)                     6
1599                  *      <pc + tp->ftt_size>                 8
1600                  * b:   <original instruction>          <= 15
1601                  *      int     T_DTRACE_RET                2
1602                  *                                      -----
1603                  *                                      <= 46
1604                  *
1605                  * The %pc is set to a, and curthread->t_dtrace_astpc is set
1606                  * to b. If we encounter a signal on the way out of the
1607                  * kernel, trap() will set %pc to curthread->t_dtrace_astpc
1608                  * so that we execute the original instruction and re-enter
1609                  * the kernel rather than redirecting to the next instruction.
1610                  *
1611                  * If there are return probes (so we know that we're going to
1612                  * need to reenter the kernel after executing the original
1613                  * instruction), the scratch space will just contain the
1614                  * original instruction followed by an interrupt -- the same
1615                  * data as at b.
1616                  *
1617                  * %rip-relative Addressing
1618                  * ------------------------
1619                  *
1620                  * There's a further complication in 64-bit mode due to %rip-
1621                  * relative addressing. While this is clearly a beneficial
1622                  * architectural decision for position independent code, it's
1623                  * hard not to see it as a personal attack against the pid
1624                  * provider since before there was a relatively small set of
1625                  * instructions to emulate; with %rip-relative addressing,
1626                  * almost every instruction can potentially depend on the
1627                  * address at which it's executed. Rather than emulating
1628                  * the broad spectrum of instructions that can now be
1629                  * position dependent, we emulate jumps and others as in
1630                  * 32-bit mode, and take a different tack for instructions
1631                  * using %rip-relative addressing.
1632                  *
1633                  * For every instruction that uses the ModRM byte, the
1634                  * in-kernel disassembler reports its location. We use the
1635                  * ModRM byte to identify that an instruction uses
1636                  * %rip-relative addressing and to see what other registers
1637                  * the instruction uses. To emulate those instructions,
1638                  * we modify the instruction to be %rax-relative rather than
1639                  * %rip-relative (or %rcx-relative if the instruction uses
1640                  * %rax; or %r8- or %r9-relative if the REX.B is present so
1641                  * we don't have to rewrite the REX prefix). We then load
1642                  * the value that %rip would have been into the scratch
1643                  * register and generate an instruction to reset the scratch
1644                  * register back to its original value. The instruction
1645                  * sequence looks like this:
1646                  *
1647                  *      64-mode %rip-relative           bytes
1648                  *      ------------------------        -----
1649                  * a:   <modified instruction>          <= 15
1650                  *      movq    $<value>, %<scratch>        6
1651                  *      jmp     0(%rip)                     6
1652                  *      <pc + tp->ftt_size>                 8
1653                  * b:   <modified instruction>          <= 15
1654                  *      int     T_DTRACE_RET                2
1655                  *                                      -----
1656                  *                                         52
1657                  *
1658                  * We set curthread->t_dtrace_regv so that upon receiving
1659                  * a signal we can reset the value of the scratch register.
1660                  */
1661
1662                 ASSERT(tp->ftt_size < FASTTRAP_MAX_INSTR_SIZE);
1663
1664                 curthread->t_dtrace_scrpc = addr;
1665                 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
1666                 i += tp->ftt_size;
1667
1668 #ifdef __amd64
1669                 if (tp->ftt_ripmode != 0) {
1670                         greg_t *reg = NULL;
1671
1672                         ASSERT(p->p_model == DATAMODEL_LP64);
1673                         ASSERT(tp->ftt_ripmode &
1674                             (FASTTRAP_RIP_1 | FASTTRAP_RIP_2));
1675
1676                         /*
1677                          * If this was a %rip-relative instruction, we change
1678                          * it to be either a %rax- or %rcx-relative
1679                          * instruction (depending on whether those registers
1680                          * are used as another operand; or %r8- or %r9-
1681                          * relative depending on the value of REX.B). We then
1682                          * set that register and generate a movq instruction
1683                          * to reset the value.
1684                          */
1685                         if (tp->ftt_ripmode & FASTTRAP_RIP_X)
1686                                 scratch[i++] = FASTTRAP_REX(1, 0, 0, 1);
1687                         else
1688                                 scratch[i++] = FASTTRAP_REX(1, 0, 0, 0);
1689
1690                         if (tp->ftt_ripmode & FASTTRAP_RIP_1)
1691                                 scratch[i++] = FASTTRAP_MOV_EAX;
1692                         else
1693                                 scratch[i++] = FASTTRAP_MOV_ECX;
1694
1695                         switch (tp->ftt_ripmode) {
1696                         case FASTTRAP_RIP_1:
1697                                 reg = &rp->r_rax;
1698                                 curthread->t_dtrace_reg = REG_RAX;
1699                                 break;
1700                         case FASTTRAP_RIP_2:
1701                                 reg = &rp->r_rcx;
1702                                 curthread->t_dtrace_reg = REG_RCX;
1703                                 break;
1704                         case FASTTRAP_RIP_1 | FASTTRAP_RIP_X:
1705                                 reg = &rp->r_r8;
1706                                 curthread->t_dtrace_reg = REG_R8;
1707                                 break;
1708                         case FASTTRAP_RIP_2 | FASTTRAP_RIP_X:
1709                                 reg = &rp->r_r9;
1710                                 curthread->t_dtrace_reg = REG_R9;
1711                                 break;
1712                         }
1713
1714                         /* LINTED - alignment */
1715                         *(uint64_t *)&scratch[i] = *reg;
1716                         curthread->t_dtrace_regv = *reg;
1717                         *reg = pc + tp->ftt_size;
1718                         i += sizeof (uint64_t);
1719                 }
1720 #endif
1721
1722                 /*
1723                  * Generate the branch instruction to what would have
1724                  * normally been the subsequent instruction. In 32-bit mode,
1725                  * this is just a relative branch; in 64-bit mode this is a
1726                  * %rip-relative branch that loads the 64-bit pc value
1727                  * immediately after the jmp instruction.
1728                  */
1729 #ifdef __amd64
1730                 if (p->p_model == DATAMODEL_LP64) {
1731                         scratch[i++] = FASTTRAP_GROUP5_OP;
1732                         scratch[i++] = FASTTRAP_MODRM(0, 4, 5);
1733                         /* LINTED - alignment */
1734                         *(uint32_t *)&scratch[i] = 0;
1735                         i += sizeof (uint32_t);
1736                         /* LINTED - alignment */
1737                         *(uint64_t *)&scratch[i] = pc + tp->ftt_size;
1738                         i += sizeof (uint64_t);
1739                 } else {
1740 #endif
1741 #ifdef __i386__
1742                         /*
1743                          * Set up the jmp to the next instruction; note that
1744                          * the size of the traced instruction cancels out.
1745                          */
1746                         scratch[i++] = FASTTRAP_JMP32;
1747                         /* LINTED - alignment */
1748                         *(uint32_t *)&scratch[i] = pc - addr - 5;
1749                         i += sizeof (uint32_t);
1750 #endif
1751 #ifdef __amd64
1752                 }
1753 #endif
1754
1755                 curthread->t_dtrace_astpc = addr + i;
1756                 bcopy(tp->ftt_instr, &scratch[i], tp->ftt_size);
1757                 i += tp->ftt_size;
1758                 scratch[i++] = FASTTRAP_INT;
1759                 scratch[i++] = T_DTRACE_RET;
1760
1761                 ASSERT(i <= sizeof (scratch));
1762
1763 #if defined(sun)
1764                 if (fasttrap_copyout(scratch, (char *)addr, i)) {
1765 #else
1766                 if (uwrite(p, scratch, i, addr)) {
1767 #endif
1768                         fasttrap_sigtrap(p, curthread, pc);
1769                         new_pc = pc;
1770                         break;
1771                 }
1772                 if (tp->ftt_retids != NULL) {
1773                         curthread->t_dtrace_step = 1;
1774                         curthread->t_dtrace_ret = 1;
1775                         new_pc = curthread->t_dtrace_astpc;
1776                 } else {
1777                         new_pc = curthread->t_dtrace_scrpc;
1778                 }
1779
1780                 curthread->t_dtrace_pc = pc;
1781                 curthread->t_dtrace_npc = pc + tp->ftt_size;
1782                 curthread->t_dtrace_on = 1;
1783                 break;
1784         }
1785
1786         default:
1787                 panic("fasttrap: mishandled an instruction");
1788         }
1789
1790 done:
1791         /*
1792          * If there were no return probes when we first found the tracepoint,
1793          * we should feel no obligation to honor any return probes that were
1794          * subsequently enabled -- they'll just have to wait until the next
1795          * time around.
1796          */
1797         if (tp->ftt_retids != NULL) {
1798                 /*
1799                  * We need to wait until the results of the instruction are
1800                  * apparent before invoking any return probes. If this
1801                  * instruction was emulated we can just call
1802                  * fasttrap_return_common(); if it needs to be executed, we
1803                  * need to wait until the user thread returns to the kernel.
1804                  */
1805                 if (tp->ftt_type != FASTTRAP_T_COMMON) {
1806                         /*
1807                          * Set the program counter to the address of the traced
1808                          * instruction so that it looks right in ustack()
1809                          * output. We had previously set it to the end of the
1810                          * instruction to simplify %rip-relative addressing.
1811                          */
1812                         rp->r_rip = pc;
1813
1814                         fasttrap_return_common(rp, pc, pid, new_pc);
1815                 } else {
1816                         ASSERT(curthread->t_dtrace_ret != 0);
1817                         ASSERT(curthread->t_dtrace_pc == pc);
1818                         ASSERT(curthread->t_dtrace_scrpc != 0);
1819                         ASSERT(new_pc == curthread->t_dtrace_astpc);
1820                 }
1821         }
1822
1823         rp->r_rip = new_pc;
1824
1825 #if !defined(sun)
1826         PROC_LOCK(p);
1827         proc_write_regs(curthread, rp);
1828         _PRELE(p);
1829         PROC_UNLOCK(p);
1830 #endif
1831
1832         return (0);
1833 }
1834
1835 int
1836 fasttrap_return_probe(struct reg *rp)
1837 {
1838         proc_t *p = curproc;
1839         uintptr_t pc = curthread->t_dtrace_pc;
1840         uintptr_t npc = curthread->t_dtrace_npc;
1841
1842         curthread->t_dtrace_pc = 0;
1843         curthread->t_dtrace_npc = 0;
1844         curthread->t_dtrace_scrpc = 0;
1845         curthread->t_dtrace_astpc = 0;
1846
1847 #if defined(sun)
1848         /*
1849          * Treat a child created by a call to vfork(2) as if it were its
1850          * parent. We know that there's only one thread of control in such a
1851          * process: this one.
1852          */
1853         while (p->p_flag & SVFORK) {
1854                 p = p->p_parent;
1855         }
1856 #endif
1857
1858         /*
1859          * We set rp->r_rip to the address of the traced instruction so
1860          * that it appears to dtrace_probe() that we're on the original
1861          * instruction, and so that the user can't easily detect our
1862          * complex web of lies. dtrace_return_probe() (our caller)
1863          * will correctly set %pc after we return.
1864          */
1865         rp->r_rip = pc;
1866
1867         fasttrap_return_common(rp, pc, p->p_pid, npc);
1868
1869         return (0);
1870 }
1871
1872 /*ARGSUSED*/
1873 uint64_t
1874 fasttrap_pid_getarg(void *arg, dtrace_id_t id, void *parg, int argno,
1875     int aframes)
1876 {
1877         struct reg r;
1878
1879         fill_regs(curthread, &r);
1880
1881         return (fasttrap_anarg(&r, 1, argno));
1882 }
1883
1884 /*ARGSUSED*/
1885 uint64_t
1886 fasttrap_usdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno,
1887     int aframes)
1888 {
1889         struct reg r;
1890
1891         fill_regs(curthread, &r);
1892
1893         return (fasttrap_anarg(&r, 0, argno));
1894 }
1895
1896 static ulong_t
1897 fasttrap_getreg(struct reg *rp, uint_t reg)
1898 {
1899 #ifdef __amd64
1900         switch (reg) {
1901         case REG_R15:           return (rp->r_r15);
1902         case REG_R14:           return (rp->r_r14);
1903         case REG_R13:           return (rp->r_r13);
1904         case REG_R12:           return (rp->r_r12);
1905         case REG_R11:           return (rp->r_r11);
1906         case REG_R10:           return (rp->r_r10);
1907         case REG_R9:            return (rp->r_r9);
1908         case REG_R8:            return (rp->r_r8);
1909         case REG_RDI:           return (rp->r_rdi);
1910         case REG_RSI:           return (rp->r_rsi);
1911         case REG_RBP:           return (rp->r_rbp);
1912         case REG_RBX:           return (rp->r_rbx);
1913         case REG_RDX:           return (rp->r_rdx);
1914         case REG_RCX:           return (rp->r_rcx);
1915         case REG_RAX:           return (rp->r_rax);
1916         case REG_TRAPNO:        return (rp->r_trapno);
1917         case REG_ERR:           return (rp->r_err);
1918         case REG_RIP:           return (rp->r_rip);
1919         case REG_CS:            return (rp->r_cs);
1920 #if defined(sun)
1921         case REG_RFL:           return (rp->r_rfl);
1922 #endif
1923         case REG_RSP:           return (rp->r_rsp);
1924         case REG_SS:            return (rp->r_ss);
1925         case REG_FS:            return (rp->r_fs);
1926         case REG_GS:            return (rp->r_gs);
1927         case REG_DS:            return (rp->r_ds);
1928         case REG_ES:            return (rp->r_es);
1929         case REG_FSBASE:        return (rdmsr(MSR_FSBASE));
1930         case REG_GSBASE:        return (rdmsr(MSR_GSBASE));
1931         }
1932
1933         panic("dtrace: illegal register constant");
1934         /*NOTREACHED*/
1935 #else
1936 #define _NGREG 19
1937         if (reg >= _NGREG)
1938                 panic("dtrace: illegal register constant");
1939
1940         return (((greg_t *)&rp->r_gs)[reg]);
1941 #endif
1942 }