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/cpuset.h>
  34 #include <sys/kernel.h>
  35 #include <sys/malloc.h>
  36 #include <sys/kmem.h>
  37 #include <sys/smp.h>
  38 #include <sys/dtrace_impl.h>
  39 #include <sys/dtrace_bsd.h>
  40 #include <machine/clock.h>
  41 #include <machine/frame.h>
  42 #include <vm/pmap.h>
  43
  44 extern uintptr_t        kernelbase;
  45 extern uintptr_t        dtrace_in_probe_addr;
  46 extern int              dtrace_in_probe;
  47
  48 int dtrace_invop(uintptr_t, uintptr_t *, uintptr_t);
  49
  50 typedef struct dtrace_invop_hdlr {
  51         int (*dtih_func)(uintptr_t, uintptr_t *, uintptr_t);
  52         struct dtrace_invop_hdlr *dtih_next;
  53 } dtrace_invop_hdlr_t;
  54
  55 dtrace_invop_hdlr_t *dtrace_invop_hdlr;
  56
  57 int
  58 dtrace_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax)
  59 {
  60         dtrace_invop_hdlr_t *hdlr;
  61         int rval;
  62
  63         for (hdlr = dtrace_invop_hdlr; hdlr != NULL; hdlr = hdlr->dtih_next)
  64                 if ((rval = hdlr->dtih_func(addr, stack, eax)) != 0)
  65                         return (rval);
  66
  67         return (0);
  68 }
  69
  70 void
  71 dtrace_invop_add(int (*func)(uintptr_t, uintptr_t *, uintptr_t))
  72 {
  73         dtrace_invop_hdlr_t *hdlr;
  74
  75         hdlr = kmem_alloc(sizeof (dtrace_invop_hdlr_t), KM_SLEEP);
  76         hdlr->dtih_func = func;
  77         hdlr->dtih_next = dtrace_invop_hdlr;
  78         dtrace_invop_hdlr = hdlr;
  79 }
  80
  81 void
  82 dtrace_invop_remove(int (*func)(uintptr_t, uintptr_t *, uintptr_t))
  83 {
  84         dtrace_invop_hdlr_t *hdlr = dtrace_invop_hdlr, *prev = NULL;
  85
  86         for (;;) {
  87                 if (hdlr == NULL)
  88                         panic("attempt to remove non-existent invop handler");
  89
  90                 if (hdlr->dtih_func == func)
  91                         break;
  92
  93                 prev = hdlr;
  94                 hdlr = hdlr->dtih_next;
  95         }
  96
  97         if (prev == NULL) {
  98                 ASSERT(dtrace_invop_hdlr == hdlr);
  99                 dtrace_invop_hdlr = hdlr->dtih_next;
 100         } else {
 101                 ASSERT(dtrace_invop_hdlr != hdlr);
 102                 prev->dtih_next = hdlr->dtih_next;
 103         }
 104
 105         kmem_free(hdlr, 0);
 106 }
 107
 108 void
 109 dtrace_toxic_ranges(void (*func)(uintptr_t base, uintptr_t limit))
 110 {
 111         (*func)(0, kernelbase);
 112 }
 113
 114 void
 115 dtrace_xcall(processorid_t cpu, dtrace_xcall_t func, void *arg)
 116 {
 117         cpuset_t cpus;
 118
 119         if (cpu == DTRACE_CPUALL)
 120                 cpus = all_cpus;
 121         else
 122                 CPU_SETOF(cpu, &cpus);
 123
 124         smp_rendezvous_cpus(cpus, smp_no_rendevous_barrier, func,
 125             smp_no_rendevous_barrier, arg);
 126 }
 127
 128 static void
 129 dtrace_sync_func(void)
 130 {
 131 }
 132
 133 void
 134 dtrace_sync(void)
 135 {
 136         dtrace_xcall(DTRACE_CPUALL, (dtrace_xcall_t)dtrace_sync_func, NULL);
 137 }
 138
 139 #ifdef notyet
 140 int (*dtrace_fasttrap_probe_ptr)(struct regs *);
 141 int (*dtrace_pid_probe_ptr)(struct regs *);
 142 int (*dtrace_return_probe_ptr)(struct regs *);
 143
 144 void
 145 dtrace_user_probe(struct regs *rp, caddr_t addr, processorid_t cpuid)
 146 {
 147         krwlock_t *rwp;
 148         proc_t *p = curproc;
 149         extern void trap(struct regs *, caddr_t, processorid_t);
 150
 151         if (USERMODE(rp->r_cs) || (rp->r_ps & PS_VM)) {
 152                 if (curthread->t_cred != p->p_cred) {
 153                         cred_t *oldcred = curthread->t_cred;
 154                         /*
 155                          * DTrace accesses t_cred in probe context.  t_cred
 156                          * must always be either NULL, or point to a valid,
 157                          * allocated cred structure.
 158                          */
 159                         curthread->t_cred = crgetcred();
 160                         crfree(oldcred);
 161                 }
 162         }
 163
 164         if (rp->r_trapno == T_DTRACE_RET) {
 165                 uint8_t step = curthread->t_dtrace_step;
 166                 uint8_t ret = curthread->t_dtrace_ret;
 167                 uintptr_t npc = curthread->t_dtrace_npc;
 168
 169                 if (curthread->t_dtrace_ast) {
 170                         aston(curthread);
 171                         curthread->t_sig_check = 1;
 172                 }
 173
 174                 /*
 175                  * Clear all user tracing flags.
 176                  */
 177                 curthread->t_dtrace_ft = 0;
 178
 179                 /*
 180                  * If we weren't expecting to take a return probe trap, kill
 181                  * the process as though it had just executed an unassigned
 182                  * trap instruction.
 183                  */
 184                 if (step == 0) {
 185                         tsignal(curthread, SIGILL);
 186                         return;
 187                 }
 188
 189                 /*
 190                  * If we hit this trap unrelated to a return probe, we're
 191                  * just here to reset the AST flag since we deferred a signal
 192                  * until after we logically single-stepped the instruction we
 193                  * copied out.
 194                  */
 195                 if (ret == 0) {
 196                         rp->r_pc = npc;
 197                         return;
 198                 }
 199
 200                 /*
 201                  * We need to wait until after we've called the
 202                  * dtrace_return_probe_ptr function pointer to set %pc.
 203                  */
 204                 rwp = &CPU->cpu_ft_lock;
 205                 rw_enter(rwp, RW_READER);
 206                 if (dtrace_return_probe_ptr != NULL)
 207                         (void) (*dtrace_return_probe_ptr)(rp);
 208                 rw_exit(rwp);
 209                 rp->r_pc = npc;
 210
 211         } else if (rp->r_trapno == T_DTRACE_PROBE) {
 212                 rwp = &CPU->cpu_ft_lock;
 213                 rw_enter(rwp, RW_READER);
 214                 if (dtrace_fasttrap_probe_ptr != NULL)
 215                         (void) (*dtrace_fasttrap_probe_ptr)(rp);
 216                 rw_exit(rwp);
 217
 218         } else if (rp->r_trapno == T_BPTFLT) {
 219                 uint8_t instr;
 220                 rwp = &CPU->cpu_ft_lock;
 221
 222                 /*
 223                  * The DTrace fasttrap provider uses the breakpoint trap
 224                  * (int 3). We let DTrace take the first crack at handling
 225                  * this trap; if it's not a probe that DTrace knowns about,
 226                  * we call into the trap() routine to handle it like a
 227                  * breakpoint placed by a conventional debugger.
 228                  */
 229                 rw_enter(rwp, RW_READER);
 230                 if (dtrace_pid_probe_ptr != NULL &&
 231                     (*dtrace_pid_probe_ptr)(rp) == 0) {
 232                         rw_exit(rwp);
 233                         return;
 234                 }
 235                 rw_exit(rwp);
 236
 237                 /*
 238                  * If the instruction that caused the breakpoint trap doesn't
 239                  * look like an int 3 anymore, it may be that this tracepoint
 240                  * was removed just after the user thread executed it. In
 241                  * that case, return to user land to retry the instuction.
 242                  */
 243                 if (fuword8((void *)(rp->r_pc - 1), &instr) == 0 &&
 244                     instr != FASTTRAP_INSTR) {
 245                         rp->r_pc--;
 246                         return;
 247                 }
 248
 249                 trap(rp, addr, cpuid);
 250
 251         } else {
 252                 trap(rp, addr, cpuid);
 253         }
 254 }
 255
 256 void
 257 dtrace_safe_synchronous_signal(void)
 258 {
 259         kthread_t *t = curthread;
 260         struct regs *rp = lwptoregs(ttolwp(t));
 261         size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
 262
 263         ASSERT(t->t_dtrace_on);
 264
 265         /*
 266          * If we're not in the range of scratch addresses, we're not actually
 267          * tracing user instructions so turn off the flags. If the instruction
 268          * we copied out caused a synchonous trap, reset the pc back to its
 269          * original value and turn off the flags.
 270          */
 271         if (rp->r_pc < t->t_dtrace_scrpc ||
 272             rp->r_pc > t->t_dtrace_astpc + isz) {
 273                 t->t_dtrace_ft = 0;
 274         } else if (rp->r_pc == t->t_dtrace_scrpc ||
 275             rp->r_pc == t->t_dtrace_astpc) {
 276                 rp->r_pc = t->t_dtrace_pc;
 277                 t->t_dtrace_ft = 0;
 278         }
 279 }
 280
 281 int
 282 dtrace_safe_defer_signal(void)
 283 {
 284         kthread_t *t = curthread;
 285         struct regs *rp = lwptoregs(ttolwp(t));
 286         size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
 287
 288         ASSERT(t->t_dtrace_on);
 289
 290         /*
 291          * If we're not in the range of scratch addresses, we're not actually
 292          * tracing user instructions so turn off the flags.
 293          */
 294         if (rp->r_pc < t->t_dtrace_scrpc ||
 295             rp->r_pc > t->t_dtrace_astpc + isz) {
 296                 t->t_dtrace_ft = 0;
 297                 return (0);
 298         }
 299
 300         /*
 301          * If we've executed the original instruction, but haven't performed
 302          * the jmp back to t->t_dtrace_npc or the clean up of any registers
 303          * used to emulate %rip-relative instructions in 64-bit mode, do that
 304          * here and take the signal right away. We detect this condition by
 305          * seeing if the program counter is the range [scrpc + isz, astpc).
 306          */
 307         if (t->t_dtrace_astpc - rp->r_pc <
 308             t->t_dtrace_astpc - t->t_dtrace_scrpc - isz) {
 309 #ifdef __amd64
 310                 /*
 311                  * If there is a scratch register and we're on the
 312                  * instruction immediately after the modified instruction,
 313                  * restore the value of that scratch register.
 314                  */
 315                 if (t->t_dtrace_reg != 0 &&
 316                     rp->r_pc == t->t_dtrace_scrpc + isz) {
 317                         switch (t->t_dtrace_reg) {
 318                         case REG_RAX:
 319                                 rp->r_rax = t->t_dtrace_regv;
 320                                 break;
 321                         case REG_RCX:
 322                                 rp->r_rcx = t->t_dtrace_regv;
 323                                 break;
 324                         case REG_R8:
 325                                 rp->r_r8 = t->t_dtrace_regv;
 326                                 break;
 327                         case REG_R9:
 328                                 rp->r_r9 = t->t_dtrace_regv;
 329                                 break;
 330                         }
 331                 }
 332 #endif
 333                 rp->r_pc = t->t_dtrace_npc;
 334                 t->t_dtrace_ft = 0;
 335                 return (0);
 336         }
 337
 338         /*
 339          * Otherwise, make sure we'll return to the kernel after executing
 340          * the copied out instruction and defer the signal.
 341          */
 342         if (!t->t_dtrace_step) {
 343                 ASSERT(rp->r_pc < t->t_dtrace_astpc);
 344                 rp->r_pc += t->t_dtrace_astpc - t->t_dtrace_scrpc;
 345                 t->t_dtrace_step = 1;
 346         }
 347
 348         t->t_dtrace_ast = 1;
 349
 350         return (1);
 351 }
 352 #endif
 353
 354 static int64_t  tgt_cpu_tsc;
 355 static int64_t  hst_cpu_tsc;
 356 static int64_t  tsc_skew[MAXCPU];
 357 static uint64_t nsec_scale;
 358
 359 /* See below for the explanation of this macro. */
 360 #define SCALE_SHIFT     28
 361
 362 static void
 363 dtrace_gethrtime_init_cpu(void *arg)
 364 {
 365         uintptr_t cpu = (uintptr_t) arg;
 366
 367         if (cpu == curcpu)
 368                 tgt_cpu_tsc = rdtsc();
 369         else
 370                 hst_cpu_tsc = rdtsc();
 371 }
 372
 373 static void
 374 dtrace_gethrtime_init(void *arg)
 375 {
 376         cpuset_t map;
 377         struct pcpu *pc;
 378         uint64_t tsc_f;
 379         int i;
 380
 381         /*
 382          * Get TSC frequency known at this moment.
 383          * This should be constant if TSC is invariant.
 384          * Otherwise tick->time conversion will be inaccurate, but
 385          * will preserve monotonic property of TSC.
 386          */
 387         tsc_f = atomic_load_acq_64(&tsc_freq);
 388
 389         /*
 390          * The following line checks that nsec_scale calculated below
 391          * doesn't overflow 32-bit unsigned integer, so that it can multiply
 392          * another 32-bit integer without overflowing 64-bit.
 393          * Thus minimum supported TSC frequency is 62.5MHz.
 394          */
 395         KASSERT(tsc_f > (NANOSEC >> (32 - SCALE_SHIFT)), ("TSC frequency is too low"));
 396
 397         /*
 398          * We scale up NANOSEC/tsc_f ratio to preserve as much precision
 399          * as possible.
 400          * 2^28 factor was chosen quite arbitrarily from practical
 401          * considerations:
 402          * - it supports TSC frequencies as low as 62.5MHz (see above);
 403          * - it provides quite good precision (e < 0.01%) up to THz
 404          *   (terahertz) values;
 405          */
 406         nsec_scale = ((uint64_t)NANOSEC << SCALE_SHIFT) / tsc_f;
 407
 408         /* The current CPU is the reference one. */
 409         sched_pin();
 410         tsc_skew[curcpu] = 0;
 411         CPU_FOREACH(i) {
 412                 if (i == curcpu)
 413                         continue;
 414
 415                 pc = pcpu_find(i);
 416                 CPU_SETOF(PCPU_GET(cpuid), &map);
 417                 CPU_SET(pc->pc_cpuid, &map);
 418
 419                 smp_rendezvous_cpus(map, NULL,
 420                     dtrace_gethrtime_init_cpu,
 421                     smp_no_rendevous_barrier, (void *)(uintptr_t) i);
 422
 423                 tsc_skew[i] = tgt_cpu_tsc - hst_cpu_tsc;
 424         }
 425         sched_unpin();
 426 }
 427
 428 SYSINIT(dtrace_gethrtime_init, SI_SUB_SMP, SI_ORDER_ANY, dtrace_gethrtime_init, NULL);
 429
 430 /*
 431  * DTrace needs a high resolution time function which can
 432  * be called from a probe context and guaranteed not to have
 433  * instrumented with probes itself.
 434  *
 435  * Returns nanoseconds since boot.
 436  */
 437 uint64_t
 438 dtrace_gethrtime()
 439 {
 440         uint64_t tsc;
 441         uint32_t lo;
 442         uint32_t hi;
 443
 444         /*
 445          * We split TSC value into lower and higher 32-bit halves and separately
 446          * scale them with nsec_scale, then we scale them down by 2^28
 447          * (see nsec_scale calculations) taking into account 32-bit shift of
 448          * the higher half and finally add.
 449          */
 450         tsc = rdtsc() + tsc_skew[curcpu];
 451         lo = tsc;
 452         hi = tsc >> 32;
 453         return (((lo * nsec_scale) >> SCALE_SHIFT) +
 454             ((hi * nsec_scale) << (32 - SCALE_SHIFT)));
 455 }
 456
 457 uint64_t
 458 dtrace_gethrestime(void)
 459 {
 460         printf("%s(%d): XXX\n",__func__,__LINE__);
 461         return (0);
 462 }
 463
 464 /* Function to handle DTrace traps during probes. See i386/i386/trap.c */
 465 int
 466 dtrace_trap(struct trapframe *frame, u_int type)
 467 {
 468         /*
 469          * A trap can occur while DTrace executes a probe. Before
 470          * executing the probe, DTrace blocks re-scheduling and sets
 471          * a flag in it's per-cpu flags to indicate that it doesn't
 472          * want to fault. On returning from the probe, the no-fault
 473          * flag is cleared and finally re-scheduling is enabled.
 474          *
 475          * Check if DTrace has enabled 'no-fault' mode:
 476          *
 477          */
 478         if ((cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT) != 0) {
 479                 /*
 480                  * There are only a couple of trap types that are expected.
 481                  * All the rest will be handled in the usual way.
 482                  */
 483                 switch (type) {
 484                 /* General protection fault. */
 485                 case T_PROTFLT:
 486                         /* Flag an illegal operation. */
 487                         cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
 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                 /* Page fault. */
 496                 case T_PAGEFLT:
 497                         /* Flag a bad address. */
 498                         cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_BADADDR;
 499                         cpu_core[curcpu].cpuc_dtrace_illval = rcr2();
 500
 501                         /*
 502                          * Offset the instruction pointer to the instruction
 503                          * following the one causing the fault.
 504                          */
 505                         frame->tf_eip += dtrace_instr_size((u_char *) frame->tf_eip);
 506                         return (1);
 507                 default:
 508                         /* Handle all other traps in the usual way. */
 509                         break;
 510                 }
 511         }
 512
 513         /* Handle the trap in the usual way. */
 514         return (0);
 515 }