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 trapframe *frame) 332 { 333 struct reg reg, *rp; 334 struct rm_priotracker tracker; 335 proc_t *p = curproc; 336 uintptr_t pc; 337 uintptr_t new_pc = 0; 338 fasttrap_bucket_t *bucket; 339 fasttrap_tracepoint_t *tp, tp_local; 340 pid_t pid; 341 dtrace_icookie_t cookie; 342 uint_t is_enabled = 0; 343 344 fill_regs(curthread, ®); 345 rp = ® 346 pc = rp->pc; 347 348 /* 349 * It's possible that a user (in a veritable orgy of bad planning) 350 * could redirect this thread's flow of control before it reached the 351 * return probe fasttrap. In this case we need to kill the process 352 * since it's in a unrecoverable state. 353 */ 354 if (curthread->t_dtrace_step) { 355 ASSERT(curthread->t_dtrace_on); 356 fasttrap_sigtrap(p, curthread, pc); 357 return (0); 358 } 359 360 /* 361 * Clear all user tracing flags. 362 */ 363 curthread->t_dtrace_ft = 0; 364 curthread->t_dtrace_pc = 0; 365 curthread->t_dtrace_npc = 0; 366 curthread->t_dtrace_scrpc = 0; 367 curthread->t_dtrace_astpc = 0; 368 369 rm_rlock(&fasttrap_tp_lock, &tracker); 370 pid = p->p_pid; 371 bucket = &fasttrap_tpoints.fth_table[FASTTRAP_TPOINTS_INDEX(pid, pc)]; 372 373 /* 374 * Lookup the tracepoint that the process just hit. 375 */ 376 for (tp = bucket->ftb_data; tp != NULL; tp = tp->ftt_next) { 377 if (pid == tp->ftt_pid && pc == tp->ftt_pc && 378 tp->ftt_proc->ftpc_acount != 0) 379 break; 380 } 381 382 /* 383 * If we couldn't find a matching tracepoint, either a tracepoint has 384 * been inserted without using the pid<pid> ioctl interface (see 385 * fasttrap_ioctl), or somehow we have mislaid this tracepoint. 386 */ 387 if (tp == NULL) { 388 rm_runlock(&fasttrap_tp_lock, &tracker); 389 return (-1); 390 } 391 392 if (tp->ftt_ids != NULL) { 393 fasttrap_id_t *id; 394 395 for (id = tp->ftt_ids; id != NULL; id = id->fti_next) { 396 fasttrap_probe_t *probe = id->fti_probe; 397 398 if (id->fti_ptype == DTFTP_ENTRY) { 399 /* 400 * We note that this was an entry 401 * probe to help ustack() find the 402 * first caller. 403 */ 404 cookie = dtrace_interrupt_disable(); 405 DTRACE_CPUFLAG_SET(CPU_DTRACE_ENTRY); 406 dtrace_probe(probe->ftp_id, rp->fixreg[3], 407 rp->fixreg[4], rp->fixreg[5], rp->fixreg[6], 408 rp->fixreg[7]); 409 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY); 410 dtrace_interrupt_enable(cookie); 411 } else if (id->fti_ptype == DTFTP_IS_ENABLED) { 412 /* 413 * Note that in this case, we don't 414 * call dtrace_probe() since it's only 415 * an artificial probe meant to change 416 * the flow of control so that it 417 * encounters the true probe. 418 */ 419 is_enabled = 1; 420 } else if (probe->ftp_argmap == NULL) { 421 dtrace_probe(probe->ftp_id, rp->fixreg[3], 422 rp->fixreg[4], rp->fixreg[5], rp->fixreg[6], 423 rp->fixreg[7]); 424 } else { 425 uintptr_t t[5]; 426 427 fasttrap_usdt_args(probe, rp, 428 sizeof (t) / sizeof (t[0]), t); 429 430 dtrace_probe(probe->ftp_id, t[0], t[1], 431 t[2], t[3], t[4]); 432 } 433 } 434 } 435 436 /* 437 * We're about to do a bunch of work so we cache a local copy of 438 * the tracepoint to emulate the instruction, and then find the 439 * tracepoint again later if we need to light up any return probes. 440 */ 441 tp_local = *tp; 442 rm_runlock(&fasttrap_tp_lock, &tracker); 443 tp = &tp_local; 444 445 /* 446 * If there's an is-enabled probe connected to this tracepoint it 447 * means that there was a 'xor r3, r3, r3' 448 * instruction that was placed there by DTrace when the binary was 449 * linked. As this probe is, in fact, enabled, we need to stuff 1 450 * into R3. Accordingly, we can bypass all the instruction 451 * emulation logic since we know the inevitable result. It's possible 452 * that a user could construct a scenario where the 'is-enabled' 453 * probe was on some other instruction, but that would be a rather 454 * exotic way to shoot oneself in the foot. 455 */ 456 if (is_enabled) { 457 rp->fixreg[3] = 1; 458 new_pc = rp->pc + 4; 459 goto done; 460 } 461 462 463 switch (tp->ftt_type) { 464 case FASTTRAP_T_NOP: 465 new_pc = rp->pc + 4; 466 break; 467 case FASTTRAP_T_BC: 468 if (!fasttrap_branch_taken(tp->ftt_bo, tp->ftt_bi, rp)) 469 break; 470 /* FALLTHROUGH */ 471 case FASTTRAP_T_B: 472 if (tp->ftt_instr & 0x01) 473 rp->lr = rp->pc + 4; 474 new_pc = tp->ftt_dest; 475 break; 476 case FASTTRAP_T_BLR: 477 case FASTTRAP_T_BCTR: 478 if (!fasttrap_branch_taken(tp->ftt_bo, tp->ftt_bi, rp)) 479 break; 480 /* FALLTHROUGH */ 481 if (tp->ftt_type == FASTTRAP_T_BCTR) 482 new_pc = rp->ctr; 483 else 484 new_pc = rp->lr; 485 if (tp->ftt_instr & 0x01) 486 rp->lr = rp->pc + 4; 487 break; 488 case FASTTRAP_T_COMMON: 489 break; 490 }; 491 done: 492 /* 493 * If there were no return probes when we first found the tracepoint, 494 * we should feel no obligation to honor any return probes that were 495 * subsequently enabled -- they'll just have to wait until the next 496 * time around. 497 */ 498 if (tp->ftt_retids != NULL) { 499 /* 500 * We need to wait until the results of the instruction are 501 * apparent before invoking any return probes. If this 502 * instruction was emulated we can just call 503 * fasttrap_return_common(); if it needs to be executed, we 504 * need to wait until the user thread returns to the kernel. 505 */ 506 if (tp->ftt_type != FASTTRAP_T_COMMON) { 507 fasttrap_return_common(rp, pc, pid, new_pc); 508 } else { 509 ASSERT(curthread->t_dtrace_ret != 0); 510 ASSERT(curthread->t_dtrace_pc == pc); 511 ASSERT(curthread->t_dtrace_scrpc != 0); 512 ASSERT(new_pc == curthread->t_dtrace_astpc); 513 } 514 } 515 516 rp->pc = new_pc; 517 set_regs(curthread, rp); 518 519 return (0); 520 } 521 522 int 523 fasttrap_return_probe(struct trapframe *tf) 524 { 525 struct reg reg, *rp; 526 proc_t *p = curproc; 527 uintptr_t pc = curthread->t_dtrace_pc; 528 uintptr_t npc = curthread->t_dtrace_npc; 529 530 curthread->t_dtrace_pc = 0; 531 curthread->t_dtrace_npc = 0; 532 curthread->t_dtrace_scrpc = 0; 533 curthread->t_dtrace_astpc = 0; 534 535 fill_regs(curthread, ®); 536 rp = ® 537 538 /* 539 * We set rp->pc to the address of the traced instruction so 540 * that it appears to dtrace_probe() that we're on the original 541 * instruction. 542 */ 543 rp->pc = pc; 544 545 fasttrap_return_common(rp, pc, p->p_pid, npc); 546 547 return (0); 548 } 549