sys/cddl/dev/dtrace/i386/dtrace_subr.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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  *
  22  * $FreeBSD$
  23  *
  24  */
  25 /*
  26  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/systm.h>
  32 #include <sys/types.h>
  33 #include <sys/kernel.h>
  34 #include <sys/malloc.h>
  35 #include <sys/kmem.h>
  36 #include <sys/smp.h>
  37 #include <sys/dtrace_impl.h>
  38 #include <sys/dtrace_bsd.h>
  39 #include <machine/clock.h>
  40 #include <machine/frame.h>
  41 #include <vm/pmap.h>
  42
  43 extern uintptr_t        kernelbase;
  44 extern uintptr_t        dtrace_in_probe_addr;
  45 extern int              dtrace_in_probe;
  46
  47 int dtrace_invop(uintptr_t, uintptr_t *, uintptr_t);
  48
  49 typedef struct dtrace_invop_hdlr {
  50         int (*dtih_func)(uintptr_t, uintptr_t *, uintptr_t);
  51         struct dtrace_invop_hdlr *dtih_next;
  52 } dtrace_invop_hdlr_t;
  53
  54 dtrace_invop_hdlr_t *dtrace_invop_hdlr;
  55
  56 int
  57 dtrace_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax)
  58 {
  59         dtrace_invop_hdlr_t *hdlr;
  60         int rval;
  61
  62         for (hdlr = dtrace_invop_hdlr; hdlr != NULL; hdlr = hdlr->dtih_next)
  63                 if ((rval = hdlr->dtih_func(addr, stack, eax)) != 0)
  64                         return (rval);
  65
  66         return (0);
  67 }
  68
  69 void
  70 dtrace_invop_add(int (*func)(uintptr_t, uintptr_t *, uintptr_t))
  71 {
  72         dtrace_invop_hdlr_t *hdlr;
  73
  74         hdlr = kmem_alloc(sizeof (dtrace_invop_hdlr_t), KM_SLEEP);
  75         hdlr->dtih_func = func;
  76         hdlr->dtih_next = dtrace_invop_hdlr;
  77         dtrace_invop_hdlr = hdlr;
  78 }
  79
  80 void
  81 dtrace_invop_remove(int (*func)(uintptr_t, uintptr_t *, uintptr_t))
  82 {
  83         dtrace_invop_hdlr_t *hdlr = dtrace_invop_hdlr, *prev = NULL;
  84
  85         for (;;) {
  86                 if (hdlr == NULL)
  87                         panic("attempt to remove non-existent invop handler");
  88
  89                 if (hdlr->dtih_func == func)
  90                         break;
  91
  92                 prev = hdlr;
  93                 hdlr = hdlr->dtih_next;
  94         }
  95
  96         if (prev == NULL) {
  97                 ASSERT(dtrace_invop_hdlr == hdlr);
  98                 dtrace_invop_hdlr = hdlr->dtih_next;
  99         } else {
 100                 ASSERT(dtrace_invop_hdlr != hdlr);
 101                 prev->dtih_next = hdlr->dtih_next;
 102         }
 103
 104         kmem_free(hdlr, 0);
 105 }
 106
 107 void
 108 dtrace_toxic_ranges(void (*func)(uintptr_t base, uintptr_t limit))
 109 {
 110         (*func)(0, kernelbase);
 111 }
 112
 113 void
 114 dtrace_xcall(processorid_t cpu, dtrace_xcall_t func, void *arg)
 115 {
 116         cpumask_t cpus;
 117
 118         critical_enter();
 119
 120         if (cpu == DTRACE_CPUALL)
 121                 cpus = all_cpus;
 122         else
 123                 cpus = (cpumask_t) (1 << cpu);
 124
 125         /* If the current CPU is in the set, call the function directly: */
 126         if ((cpus & (1 << curcpu)) != 0) {
 127                 (*func)(arg);
 128
 129                 /* Mask the current CPU from the set */
 130                 cpus &= ~(1 << curcpu);
 131         }
 132
 133         /* If there are any CPUs in the set, cross-call to those CPUs */
 134         if (cpus != 0)
 135                 smp_rendezvous_cpus(cpus, NULL, func, smp_no_rendevous_barrier, arg);
 136
 137         critical_exit();
 138 }
 139
 140 static void
 141 dtrace_sync_func(void)
 142 {
 143 }
 144
 145 void
 146 dtrace_sync(void)
 147 {
 148         dtrace_xcall(DTRACE_CPUALL, (dtrace_xcall_t)dtrace_sync_func, NULL);
 149 }
 150
 151 #ifdef notyet
 152 int (*dtrace_fasttrap_probe_ptr)(struct regs *);
 153 int (*dtrace_pid_probe_ptr)(struct regs *);
 154 int (*dtrace_return_probe_ptr)(struct regs *);
 155
 156 void
 157 dtrace_user_probe(struct regs *rp, caddr_t addr, processorid_t cpuid)
 158 {
 159         krwlock_t *rwp;
 160         proc_t *p = curproc;
 161         extern void trap(struct regs *, caddr_t, processorid_t);
 162
 163         if (USERMODE(rp->r_cs) || (rp->r_ps & PS_VM)) {
 164                 if (curthread->t_cred != p->p_cred) {
 165                         cred_t *oldcred = curthread->t_cred;
 166                         /*
 167                          * DTrace accesses t_cred in probe context.  t_cred
 168                          * must always be either NULL, or point to a valid,
 169                          * allocated cred structure.
 170                          */
 171                         curthread->t_cred = crgetcred();
 172                         crfree(oldcred);
 173                 }
 174         }
 175
 176         if (rp->r_trapno == T_DTRACE_RET) {
 177                 uint8_t step = curthread->t_dtrace_step;
 178                 uint8_t ret = curthread->t_dtrace_ret;
 179                 uintptr_t npc = curthread->t_dtrace_npc;
 180
 181                 if (curthread->t_dtrace_ast) {
 182                         aston(curthread);
 183                         curthread->t_sig_check = 1;
 184                 }
 185
 186                 /*
 187                  * Clear all user tracing flags.
 188                  */
 189                 curthread->t_dtrace_ft = 0;
 190
 191                 /*
 192                  * If we weren't expecting to take a return probe trap, kill
 193                  * the process as though it had just executed an unassigned
 194                  * trap instruction.
 195                  */
 196                 if (step == 0) {
 197                         tsignal(curthread, SIGILL);
 198                         return;
 199                 }
 200
 201                 /*
 202                  * If we hit this trap unrelated to a return probe, we're
 203                  * just here to reset the AST flag since we deferred a signal
 204                  * until after we logically single-stepped the instruction we
 205                  * copied out.
 206                  */
 207                 if (ret == 0) {
 208                         rp->r_pc = npc;
 209                         return;
 210                 }
 211
 212                 /*
 213                  * We need to wait until after we've called the
 214                  * dtrace_return_probe_ptr function pointer to set %pc.
 215                  */
 216                 rwp = &CPU->cpu_ft_lock;
 217                 rw_enter(rwp, RW_READER);
 218                 if (dtrace_return_probe_ptr != NULL)
 219                         (void) (*dtrace_return_probe_ptr)(rp);
 220                 rw_exit(rwp);
 221                 rp->r_pc = npc;
 222
 223         } else if (rp->r_trapno == T_DTRACE_PROBE) {
 224                 rwp = &CPU->cpu_ft_lock;
 225                 rw_enter(rwp, RW_READER);
 226                 if (dtrace_fasttrap_probe_ptr != NULL)
 227                         (void) (*dtrace_fasttrap_probe_ptr)(rp);
 228                 rw_exit(rwp);
 229
 230         } else if (rp->r_trapno == T_BPTFLT) {
 231                 uint8_t instr;
 232                 rwp = &CPU->cpu_ft_lock;
 233
 234                 /*
 235                  * The DTrace fasttrap provider uses the breakpoint trap
 236                  * (int 3). We let DTrace take the first crack at handling
 237                  * this trap; if it's not a probe that DTrace knowns about,
 238                  * we call into the trap() routine to handle it like a
 239                  * breakpoint placed by a conventional debugger.
 240                  */
 241                 rw_enter(rwp, RW_READER);
 242                 if (dtrace_pid_probe_ptr != NULL &&
 243                     (*dtrace_pid_probe_ptr)(rp) == 0) {
 244                         rw_exit(rwp);
 245                         return;
 246                 }
 247                 rw_exit(rwp);
 248
 249                 /*
 250                  * If the instruction that caused the breakpoint trap doesn't
 251                  * look like an int 3 anymore, it may be that this tracepoint
 252                  * was removed just after the user thread executed it. In
 253                  * that case, return to user land to retry the instuction.
 254                  */
 255                 if (fuword8((void *)(rp->r_pc - 1), &instr) == 0 &&
 256                     instr != FASTTRAP_INSTR) {
 257                         rp->r_pc--;
 258                         return;
 259                 }
 260
 261                 trap(rp, addr, cpuid);
 262
 263         } else {
 264                 trap(rp, addr, cpuid);
 265         }
 266 }
 267
 268 void
 269 dtrace_safe_synchronous_signal(void)
 270 {
 271         kthread_t *t = curthread;
 272         struct regs *rp = lwptoregs(ttolwp(t));
 273         size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
 274
 275         ASSERT(t->t_dtrace_on);
 276
 277         /*
 278          * If we're not in the range of scratch addresses, we're not actually
 279          * tracing user instructions so turn off the flags. If the instruction
 280          * we copied out caused a synchonous trap, reset the pc back to its
 281          * original value and turn off the flags.
 282          */
 283         if (rp->r_pc < t->t_dtrace_scrpc ||
 284             rp->r_pc > t->t_dtrace_astpc + isz) {
 285                 t->t_dtrace_ft = 0;
 286         } else if (rp->r_pc == t->t_dtrace_scrpc ||
 287             rp->r_pc == t->t_dtrace_astpc) {
 288                 rp->r_pc = t->t_dtrace_pc;
 289                 t->t_dtrace_ft = 0;
 290         }
 291 }
 292
 293 int
 294 dtrace_safe_defer_signal(void)
 295 {
 296         kthread_t *t = curthread;
 297         struct regs *rp = lwptoregs(ttolwp(t));
 298         size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
 299
 300         ASSERT(t->t_dtrace_on);
 301
 302         /*
 303          * If we're not in the range of scratch addresses, we're not actually
 304          * tracing user instructions so turn off the flags.
 305          */
 306         if (rp->r_pc < t->t_dtrace_scrpc ||
 307             rp->r_pc > t->t_dtrace_astpc + isz) {
 308                 t->t_dtrace_ft = 0;
 309                 return (0);
 310         }
 311
 312         /*
 313          * If we've executed the original instruction, but haven't performed
 314          * the jmp back to t->t_dtrace_npc or the clean up of any registers
 315          * used to emulate %rip-relative instructions in 64-bit mode, do that
 316          * here and take the signal right away. We detect this condition by
 317          * seeing if the program counter is the range [scrpc + isz, astpc).
 318          */
 319         if (t->t_dtrace_astpc - rp->r_pc <
 320             t->t_dtrace_astpc - t->t_dtrace_scrpc - isz) {
 321 #ifdef __amd64
 322                 /*
 323                  * If there is a scratch register and we're on the
 324                  * instruction immediately after the modified instruction,
 325                  * restore the value of that scratch register.
 326                  */
 327                 if (t->t_dtrace_reg != 0 &&
 328                     rp->r_pc == t->t_dtrace_scrpc + isz) {
 329                         switch (t->t_dtrace_reg) {
 330                         case REG_RAX:
 331                                 rp->r_rax = t->t_dtrace_regv;
 332                                 break;
 333                         case REG_RCX:
 334                                 rp->r_rcx = t->t_dtrace_regv;
 335                                 break;
 336                         case REG_R8:
 337                                 rp->r_r8 = t->t_dtrace_regv;
 338                                 break;
 339                         case REG_R9:
 340                                 rp->r_r9 = t->t_dtrace_regv;
 341                                 break;
 342                         }
 343                 }
 344 #endif
 345                 rp->r_pc = t->t_dtrace_npc;
 346                 t->t_dtrace_ft = 0;
 347                 return (0);
 348         }
 349
 350         /*
 351          * Otherwise, make sure we'll return to the kernel after executing
 352          * the copied out instruction and defer the signal.
 353          */
 354         if (!t->t_dtrace_step) {
 355                 ASSERT(rp->r_pc < t->t_dtrace_astpc);
 356                 rp->r_pc += t->t_dtrace_astpc - t->t_dtrace_scrpc;
 357                 t->t_dtrace_step = 1;
 358         }
 359
 360         t->t_dtrace_ast = 1;
 361
 362         return (1);
 363 }
 364 #endif
 365
 366 static int64_t  tgt_cpu_tsc;
 367 static int64_t  hst_cpu_tsc;
 368 static int64_t  tsc_skew[MAXCPU];
 369
 370 static void
 371 dtrace_gethrtime_init_sync(void *arg)
 372 {
 373 #ifdef CHECK_SYNC
 374         /*
 375          * Delay this function from returning on one
 376          * of the CPUs to check that the synchronisation
 377          * works.
 378          */
 379         uintptr_t cpu = (uintptr_t) arg;
 380
 381         if (cpu == curcpu) {
 382                 int i;
 383                 for (i = 0; i < 1000000000; i++)
 384                         tgt_cpu_tsc = rdtsc();
 385                 tgt_cpu_tsc = 0;
 386         }
 387 #endif
 388 }
 389
 390 static void
 391 dtrace_gethrtime_init_cpu(void *arg)
 392 {
 393         uintptr_t cpu = (uintptr_t) arg;
 394
 395         if (cpu == curcpu)
 396                 tgt_cpu_tsc = rdtsc();
 397         else
 398                 hst_cpu_tsc = rdtsc();
 399 }
 400
 401 static void
 402 dtrace_gethrtime_init(void *arg)
 403 {
 404         cpumask_t map;
 405         int i;
 406         struct pcpu *cp;
 407
 408         /* The current CPU is the reference one. */
 409         tsc_skew[curcpu] = 0;
 410
 411         for (i = 0; i <= mp_maxid; i++) {
 412                 if (i == curcpu)
 413                         continue;
 414
 415                 if ((cp = pcpu_find(i)) == NULL)
 416                         continue;
 417
 418                 map = 0;
 419                 map |= (1 << curcpu);
 420                 map |= (1 << i);
 421
 422                 smp_rendezvous_cpus(map, dtrace_gethrtime_init_sync,
 423                     dtrace_gethrtime_init_cpu,
 424                     smp_no_rendevous_barrier, (void *)(uintptr_t) i);
 425
 426                 tsc_skew[i] = tgt_cpu_tsc - hst_cpu_tsc;
 427         }
 428 }
 429
 430 SYSINIT(dtrace_gethrtime_init, SI_SUB_SMP, SI_ORDER_ANY, dtrace_gethrtime_init, NULL);
 431
 432 /*
 433  * DTrace needs a high resolution time function which can
 434  * be called from a probe context and guaranteed not to have
 435  * instrumented with probes itself.
 436  *
 437  * Returns nanoseconds since boot.
 438  */
 439 uint64_t
 440 dtrace_gethrtime()
 441 {
 442         return ((rdtsc() + tsc_skew[curcpu]) * (int64_t) 1000000000 / tsc_freq);
 443 }
 444
 445 uint64_t
 446 dtrace_gethrestime(void)
 447 {
 448         printf("%s(%d): XXX\n",__func__,__LINE__);
 449         return (0);
 450 }
 451
 452 /* Function to handle DTrace traps during probes. See i386/i386/trap.c */
 453 int
 454 dtrace_trap(struct trapframe *frame, u_int type)
 455 {
 456         /*
 457          * A trap can occur while DTrace executes a probe. Before
 458          * executing the probe, DTrace blocks re-scheduling and sets
 459          * a flag in it's per-cpu flags to indicate that it doesn't
 460          * want to fault. On returning from the the probe, the no-fault
 461          * flag is cleared and finally re-scheduling is enabled.
 462          *
 463          * Check if DTrace has enabled 'no-fault' mode:
 464          *
 465          */
 466         if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) != 0) {
 467                 /*
 468                  * There are only a couple of trap types that are expected.
 469                  * All the rest will be handled in the usual way.
 470                  */
 471                 switch (type) {
 472                 /* General protection fault. */
 473                 case T_PROTFLT:
 474                         /* Flag an illegal operation. */
 475                         cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
 476
 477                         /*
 478                          * Offset the instruction pointer to the instruction
 479                          * following the one causing the fault.
 480                          */
 481                         frame->tf_eip += dtrace_instr_size((u_char *) frame->tf_eip);
 482                         return (1);
 483                 /* Page fault. */
 484                 case T_PAGEFLT:
 485                         /* Flag a bad address. */
 486                         cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_BADADDR;
 487                         cpu_core[curcpu].cpuc_dtrace_illval = rcr2();
 488
 489                         /*
 490                          * Offset the instruction pointer to the instruction
 491                          * following the one causing the fault.
 492                          */
 493                         frame->tf_eip += dtrace_instr_size((u_char *) frame->tf_eip);
 494                         return (1);
 495                 default:
 496                         /* Handle all other traps in the usual way. */
 497                         break;
 498                 }
 499         }
 500
 501         /* Handle the trap in the usual way. */
 502         return (0);
 503 }