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 2013 Justin Hibbits */ 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #include <sys/fasttrap_isa.h> 28 #include <sys/fasttrap_impl.h> 29 #include <sys/dtrace.h> 30 #include <sys/dtrace_impl.h> 31 #include <cddl/dev/dtrace/dtrace_cddl.h> 32 #include <sys/proc.h> 33 #include <sys/types.h> 34 #include <sys/uio.h> 35 #include <sys/ptrace.h> 36 #include <sys/rmlock.h> 37 #include <sys/sysent.h> 38 39 #define OP(x) ((x) >> 26) 40 #define OPX(x) (((x) >> 2) & 0x3FF) 41 #define OP_BO(x) (((x) & 0x03E00000) >> 21) 42 #define OP_BI(x) (((x) & 0x001F0000) >> 16) 43 #define OP_RS(x) (((x) & 0x03E00000) >> 21) 44 #define OP_RA(x) (((x) & 0x001F0000) >> 16) 45 #define OP_RB(x) (((x) & 0x0000F100) >> 11) 46 47 int 48 fasttrap_tracepoint_install(proc_t *p, fasttrap_tracepoint_t *tp) 49 { 50 fasttrap_instr_t instr = FASTTRAP_INSTR; 51 52 if (uwrite(p, &instr, 4, tp->ftt_pc) != 0) 53 return (-1); 54 55 return (0); 56 } 57 58 int 59 fasttrap_tracepoint_remove(proc_t *p, fasttrap_tracepoint_t *tp) 60 { 61 uint32_t instr; 62 63 /* 64 * Distinguish between read or write failures and a changed 65 * instruction. 66 */ 67 if (uread(p, &instr, 4, tp->ftt_pc) != 0) 68 return (0); 69 if (instr != FASTTRAP_INSTR) 70 return (0); 71 if (uwrite(p, &tp->ftt_instr, 4, tp->ftt_pc) != 0) 72 return (-1); 73 74 return (0); 75 } 76 77 int 78 fasttrap_tracepoint_init(proc_t *p, fasttrap_tracepoint_t *tp, uintptr_t pc, 79 fasttrap_probe_type_t type) 80 { 81 uint32_t instr; 82 //int32_t disp; 83 84 /* 85 * Read the instruction at the given address out of the process's 86 * address space. We don't have to worry about a debugger 87 * changing this instruction before we overwrite it with our trap 88 * instruction since P_PR_LOCK is set. 89 */ 90 if (uread(p, &instr, 4, pc) != 0) 91 return (-1); 92 93 /* 94 * Decode the instruction to fill in the probe flags. We can have 95 * the process execute most instructions on its own using a pc/npc 96 * trick, but pc-relative control transfer present a problem since 97 * we're relocating the instruction. We emulate these instructions 98 * in the kernel. We assume a default type and over-write that as 99 * needed. 100 * 101 * pc-relative instructions must be emulated for correctness; 102 * other instructions (which represent a large set of commonly traced 103 * instructions) are emulated or otherwise optimized for performance. 104 */ 105 tp->ftt_type = FASTTRAP_T_COMMON; 106 tp->ftt_instr = instr; 107 108 switch (OP(instr)) { 109 /* The following are invalid for trapping (invalid opcodes, tw/twi). */ 110 case 0: 111 case 1: 112 case 2: 113 case 4: 114 case 5: 115 case 6: 116 case 30: 117 case 39: 118 case 58: 119 case 62: 120 case 3: /* twi */ 121 return (-1); 122 case 31: /* tw */ 123 if (OPX(instr) == 4) 124 return (-1); 125 else if (OPX(instr) == 444 && OP_RS(instr) == OP_RA(instr) && 126 OP_RS(instr) == OP_RB(instr)) 127 tp->ftt_type = FASTTRAP_T_NOP; 128 break; 129 case 16: 130 tp->ftt_type = FASTTRAP_T_BC; 131 tp->ftt_dest = instr & 0x0000FFFC; /* Extract target address */ 132 if (instr & 0x00008000) 133 tp->ftt_dest |= 0xFFFF0000; 134 /* Use as offset if not absolute address. */ 135 if (!(instr & 0x02)) 136 tp->ftt_dest += pc; 137 tp->ftt_bo = OP_BO(instr); 138 tp->ftt_bi = OP_BI(instr); 139 break; 140 case 18: 141 tp->ftt_type = FASTTRAP_T_B; 142 tp->ftt_dest = instr & 0x03FFFFFC; /* Extract target address */ 143 if (instr & 0x02000000) 144 tp->ftt_dest |= 0xFC000000; 145 /* Use as offset if not absolute address. */ 146 if (!(instr & 0x02)) 147 tp->ftt_dest += pc; 148 break; 149 case 19: 150 switch (OPX(instr)) { 151 case 528: /* bcctr */ 152 tp->ftt_type = FASTTRAP_T_BCTR; 153 tp->ftt_bo = OP_BO(instr); 154 tp->ftt_bi = OP_BI(instr); 155 break; 156 case 16: /* bclr */ 157 tp->ftt_type = FASTTRAP_T_BCTR; 158 tp->ftt_bo = OP_BO(instr); 159 tp->ftt_bi = OP_BI(instr); 160 break; 161 }; 162 break; 163 case 24: 164 if (OP_RS(instr) == OP_RA(instr) && 165 (instr & 0x0000FFFF) == 0) 166 tp->ftt_type = FASTTRAP_T_NOP; 167 break; 168 }; 169 170 /* 171 * We don't know how this tracepoint is going to be used, but in case 172 * it's used as part of a function return probe, we need to indicate 173 * whether it's always a return site or only potentially a return 174 * site. If it's part of a return probe, it's always going to be a 175 * return from that function if it's a restore instruction or if 176 * the previous instruction was a return. If we could reliably 177 * distinguish jump tables from return sites, this wouldn't be 178 * necessary. 179 */ 180 #if 0 181 if (tp->ftt_type != FASTTRAP_T_RESTORE && 182 (uread(p, &instr, 4, pc - sizeof (instr)) != 0 || 183 !(OP(instr) == 2 && OP3(instr) == OP3_RETURN))) 184 tp->ftt_flags |= FASTTRAP_F_RETMAYBE; 185 #endif 186 187 return (0); 188 } 189 190 static uint64_t 191 fasttrap_anarg(struct reg *rp, int argno) 192 { 193 uint64_t value; 194 proc_t *p = curproc; 195 196 /* The first 8 arguments are in registers. */ 197 if (argno < 8) 198 return rp->fixreg[argno + 3]; 199 200 /* Arguments on stack start after SP+LR (2 register slots). */ 201 if (SV_PROC_FLAG(p, SV_ILP32)) { 202 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT); 203 value = dtrace_fuword32((void *)(rp->fixreg[1] + 8 + 204 ((argno - 8) * sizeof(uint32_t)))); 205 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR); 206 } else { 207 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT); 208 value = dtrace_fuword64((void *)(rp->fixreg[1] + 48 + 209 ((argno - 8) * sizeof(uint64_t)))); 210 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT | CPU_DTRACE_BADADDR); 211 } 212 return value; 213 } 214 215 uint64_t 216 fasttrap_pid_getarg(void *arg, dtrace_id_t id, void *parg, int argno, 217 int aframes) 218 { 219 struct reg r; 220 221 fill_regs(curthread, &r); 222 223 return (fasttrap_anarg(&r, argno)); 224 } 225 226 uint64_t 227 fasttrap_usdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno, 228 int aframes) 229 { 230 struct reg r; 231 232 fill_regs(curthread, &r); 233 234 return (fasttrap_anarg(&r, argno)); 235 } 236 237 static void 238 fasttrap_usdt_args(fasttrap_probe_t *probe, struct reg *rp, int argc, 239 uintptr_t *argv) 240 { 241 int i, x, cap = MIN(argc, probe->ftp_nargs); 242 243 for (i = 0; i < cap; i++) { 244 x = probe->ftp_argmap[i]; 245 246 if (x < 8) 247 argv[i] = rp->fixreg[x]; 248 else 249 if (SV_PROC_FLAG(curproc, SV_ILP32)) 250 argv[i] = fuword32((void *)(rp->fixreg[1] + 8 + 251 (x * sizeof(uint32_t)))); 252 else 253 argv[i] = fuword64((void *)(rp->fixreg[1] + 48 + 254 (x * sizeof(uint64_t)))); 255 } 256 257 for (; i < argc; i++) { 258 argv[i] = 0; 259 } 260 } 261 262 static void 263 fasttrap_return_common(struct reg *rp, uintptr_t pc, pid_t pid, 264 uintptr_t new_pc) 265 { 266 struct rm_priotracker tracker; 267 fasttrap_tracepoint_t *tp; 268 fasttrap_bucket_t *bucket; 269 fasttrap_id_t *id; 270 271 rm_rlock(&fasttrap_tp_lock, &tracker); 272 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)]; 273 274 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) { 275 if (pid == tp->ftt_pid && pc == tp->ftt_pc && 276 tp->ftt_proc->ftpc_acount != 0) 277 break; 278 } 279 280 /* 281 * Don't sweat it if we can't find the tracepoint again; unlike 282 * when we're in fasttrap_pid_probe(), finding the tracepoint here 283 * is not essential to the correct execution of the process. 284 */ 285 if (tp == NULL) { 286 rm_runlock(&fasttrap_tp_lock, &tracker); 287 return; 288 } 289 290 for (id = tp->ftt_retids; id != NULL; id = id->fti_next) { 291 /* 292 * If there's a branch that could act as a return site, we 293 * need to trace it, and check here if the program counter is 294 * external to the function. 295 */ 296 /* Skip function-local branches. */ 297 if ((new_pc - id->fti_probe->ftp_faddr) < id->fti_probe->ftp_fsize) 298 continue; 299 300 dtrace_probe(id->fti_probe->ftp_id, 301 pc - id->fti_probe->ftp_faddr, 302 rp->fixreg[3], rp->fixreg[4], 0, 0); 303 } 304 rm_runlock(&fasttrap_tp_lock, &tracker); 305 } 306 307 308 static int 309 fasttrap_branch_taken(int bo, int bi, struct reg *regs) 310 { 311 int crzero = 0; 312 313 /* Branch always? */ 314 if ((bo & 0x14) == 0x14) 315 return 1; 316 317 /* Handle decrementing ctr */ 318 if (!(bo & 0x04)) { 319 --regs->ctr; 320 crzero = (regs->ctr == 0); 321 if (bo & 0x10) { 322 return (!(crzero ^ (bo >> 1))); 323 } 324 } 325 326 return (crzero | (((regs->cr >> (31 - bi)) ^ (bo >> 3)) ^ 1)); 327 } 328 329 330 int 331 fasttrap_pid_probe(struct reg *rp) 332 { 333 struct rm_priotracker tracker; 334 proc_t *p = curproc; 335 uintptr_t pc = rp->pc; 336 uintptr_t new_pc = 0; 337 fasttrap_bucket_t *bucket; 338 fasttrap_tracepoint_t *tp, tp_local; 339 pid_t pid; 340 dtrace_icookie_t cookie; 341 uint_t is_enabled = 0; 342 343 /* 344 * It's possible that a user (in a veritable orgy of bad planning) 345 * could redirect this thread's flow of control before it reached the 346 * return probe fasttrap. In this case we need to kill the process 347 * since it's in a unrecoverable state. 348 */ 349 if (curthread->t_dtrace_step) { 350 ASSERT(curthread->t_dtrace_on); 351 fasttrap_sigtrap(p, curthread, pc); 352 return (0); 353 } 354 355 /* 356 * Clear all user tracing flags. 357 */ 358 curthread->t_dtrace_ft = 0; 359 curthread->t_dtrace_pc = 0; 360 curthread->t_dtrace_npc = 0; 361 curthread->t_dtrace_scrpc = 0; 362 curthread->t_dtrace_astpc = 0; 363 364 rm_rlock(&fasttrap_tp_lock, &tracker); 365 pid = p->p_pid; 366 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)]; 367 368 /* 369 * Lookup the tracepoint that the process just hit. 370 */ 371 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) { 372 if (pid == tp->ftt_pid && pc == tp->ftt_pc && 373 tp->ftt_proc->ftpc_acount != 0) 374 break; 375 } 376 377 /* 378 * If we couldn't find a matching tracepoint, either a tracepoint has 379 * been inserted without using the pid<pid> ioctl interface (see 380 * fasttrap_ioctl), or somehow we have mislaid this tracepoint. 381 */ 382 if (tp == NULL) { 383 rm_runlock(&fasttrap_tp_lock, &tracker); 384 return (-1); 385 } 386 387 if (tp->ftt_ids != NULL) { 388 fasttrap_id_t *id; 389 390 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) { 391 fasttrap_probe_t *probe = id->fti_probe; 392 393 if (id->fti_ptype == DTFTP_ENTRY) { 394 /* 395 * We note that this was an entry 396 * probe to help ustack() find the 397 * first caller. 398 */ 399 cookie = dtrace_interrupt_disable(); 400 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY); 401 dtrace_probe(probe->ftp_id, rp->fixreg[3], 402 rp->fixreg[4], rp->fixreg[5], rp->fixreg[6], 403 rp->fixreg[7]); 404 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY); 405 dtrace_interrupt_enable(cookie); 406 } else if (id->fti_ptype == DTFTP_IS_ENABLED) { 407 /* 408 * Note that in this case, we don't 409 * call dtrace_probe() since it's only 410 * an artificial probe meant to change 411 * the flow of control so that it 412 * encounters the true probe. 413 */ 414 is_enabled = 1; 415 } else if (probe->ftp_argmap == NULL) { 416 dtrace_probe(probe->ftp_id, rp->fixreg[3], 417 rp->fixreg[4], rp->fixreg[5], rp->fixreg[6], 418 rp->fixreg[7]); 419 } else { 420 uintptr_t t[5]; 421 422 fasttrap_usdt_args(probe, rp, 423 sizeof (t) / sizeof (t[0]), t); 424 425 dtrace_probe(probe->ftp_id, t[0], t[1], 426 t[2], t[3], t[4]); 427 } 428 } 429 } 430 431 /* 432 * We're about to do a bunch of work so we cache a local copy of 433 * the tracepoint to emulate the instruction, and then find the 434 * tracepoint again later if we need to light up any return probes. 435 */ 436 tp_local = *tp; 437 rm_runlock(&fasttrap_tp_lock, &tracker); 438 tp = &tp_local; 439 440 /* 441 * If there's an is-enabled probe connected to this tracepoint it 442 * means that there was a 'xor r3, r3, r3' 443 * instruction that was placed there by DTrace when the binary was 444 * linked. As this probe is, in fact, enabled, we need to stuff 1 445 * into R3. Accordingly, we can bypass all the instruction 446 * emulation logic since we know the inevitable result. It's possible 447 * that a user could construct a scenario where the 'is-enabled' 448 * probe was on some other instruction, but that would be a rather 449 * exotic way to shoot oneself in the foot. 450 */ 451 if (is_enabled) { 452 rp->fixreg[3] = 1; 453 new_pc = rp->pc + 4; 454 goto done; 455 } 456 457 458 switch (tp->ftt_type) { 459 case FASTTRAP_T_NOP: 460 new_pc = rp->pc + 4; 461 break; 462 case FASTTRAP_T_BC: 463 if (!fasttrap_branch_taken(tp->ftt_bo, tp->ftt_bi, rp)) 464 break; 465 /* FALLTHROUGH */ 466 case FASTTRAP_T_B: 467 if (tp->ftt_instr & 0x01) 468 rp->lr = rp->pc + 4; 469 new_pc = tp->ftt_dest; 470 break; 471 case FASTTRAP_T_BLR: 472 case FASTTRAP_T_BCTR: 473 if (!fasttrap_branch_taken(tp->ftt_bo, tp->ftt_bi, rp)) 474 break; 475 /* FALLTHROUGH */ 476 if (tp->ftt_type == FASTTRAP_T_BCTR) 477 new_pc = rp->ctr; 478 else 479 new_pc = rp->lr; 480 if (tp->ftt_instr & 0x01) 481 rp->lr = rp->pc + 4; 482 break; 483 case FASTTRAP_T_COMMON: 484 break; 485 }; 486 done: 487 /* 488 * If there were no return probes when we first found the tracepoint, 489 * we should feel no obligation to honor any return probes that were 490 * subsequently enabled -- they'll just have to wait until the next 491 * time around. 492 */ 493 if (tp->ftt_retids != NULL) { 494 /* 495 * We need to wait until the results of the instruction are 496 * apparent before invoking any return probes. If this 497 * instruction was emulated we can just call 498 * fasttrap_return_common(); if it needs to be executed, we 499 * need to wait until the user thread returns to the kernel. 500 */ 501 if (tp->ftt_type != FASTTRAP_T_COMMON) { 502 fasttrap_return_common(rp, pc, pid, new_pc); 503 } else { 504 ASSERT(curthread->t_dtrace_ret != 0); 505 ASSERT(curthread->t_dtrace_pc == pc); 506 ASSERT(curthread->t_dtrace_scrpc != 0); 507 ASSERT(new_pc == curthread->t_dtrace_astpc); 508 } 509 } 510 511 rp->pc = new_pc; 512 set_regs(curthread, rp); 513 514 return (0); 515 } 516 517 int 518 fasttrap_return_probe(struct reg *rp) 519 { 520 proc_t *p = curproc; 521 uintptr_t pc = curthread->t_dtrace_pc; 522 uintptr_t npc = curthread->t_dtrace_npc; 523 524 curthread->t_dtrace_pc = 0; 525 curthread->t_dtrace_npc = 0; 526 curthread->t_dtrace_scrpc = 0; 527 curthread->t_dtrace_astpc = 0; 528 529 /* 530 * We set rp->pc to the address of the traced instruction so 531 * that it appears to dtrace_probe() that we're on the original 532 * instruction, and so that the user can't easily detect our 533 * complex web of lies. dtrace_return_probe() (our caller) 534 * will correctly set %pc after we return. 535 */ 536 rp->pc = pc; 537 538 fasttrap_return_common(rp, pc, p->p_pid, npc); 539 540 return (0); 541 } 542 543