The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/trap.c

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    1 /*-
    2  * Copyright (C) 1994, David Greenman
    3  * Copyright (c) 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the University of Utah, and William Jolitz.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. All advertising materials mentioning features or use of this software
   18  *    must display the following acknowledgement:
   19  *      This product includes software developed by the University of
   20  *      California, Berkeley and its contributors.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      from: @(#)trap.c        7.4 (Berkeley) 5/13/91
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: releng/9.0/sys/i386/i386/trap.c 227946 2011-11-24 18:44:14Z rstone $");
   42 
   43 /*
   44  * 386 Trap and System call handling
   45  */
   46 
   47 #include "opt_clock.h"
   48 #include "opt_cpu.h"
   49 #include "opt_hwpmc_hooks.h"
   50 #include "opt_isa.h"
   51 #include "opt_kdb.h"
   52 #include "opt_kdtrace.h"
   53 #include "opt_npx.h"
   54 #include "opt_trap.h"
   55 
   56 #include <sys/param.h>
   57 #include <sys/bus.h>
   58 #include <sys/systm.h>
   59 #include <sys/proc.h>
   60 #include <sys/pioctl.h>
   61 #include <sys/ptrace.h>
   62 #include <sys/kdb.h>
   63 #include <sys/kernel.h>
   64 #include <sys/ktr.h>
   65 #include <sys/lock.h>
   66 #include <sys/mutex.h>
   67 #include <sys/resourcevar.h>
   68 #include <sys/signalvar.h>
   69 #include <sys/syscall.h>
   70 #include <sys/sysctl.h>
   71 #include <sys/sysent.h>
   72 #include <sys/uio.h>
   73 #include <sys/vmmeter.h>
   74 #ifdef HWPMC_HOOKS
   75 #include <sys/pmckern.h>
   76 #endif
   77 #include <security/audit/audit.h>
   78 
   79 #include <vm/vm.h>
   80 #include <vm/vm_param.h>
   81 #include <vm/pmap.h>
   82 #include <vm/vm_kern.h>
   83 #include <vm/vm_map.h>
   84 #include <vm/vm_page.h>
   85 #include <vm/vm_extern.h>
   86 
   87 #include <machine/cpu.h>
   88 #include <machine/intr_machdep.h>
   89 #include <x86/mca.h>
   90 #include <machine/md_var.h>
   91 #include <machine/pcb.h>
   92 #ifdef SMP
   93 #include <machine/smp.h>
   94 #endif
   95 #include <machine/tss.h>
   96 #include <machine/vm86.h>
   97 
   98 #ifdef POWERFAIL_NMI
   99 #include <sys/syslog.h>
  100 #include <machine/clock.h>
  101 #endif
  102 
  103 #ifdef KDTRACE_HOOKS
  104 #include <sys/dtrace_bsd.h>
  105 
  106 /*
  107  * This is a hook which is initialised by the dtrace module
  108  * to handle traps which might occur during DTrace probe
  109  * execution.
  110  */
  111 dtrace_trap_func_t      dtrace_trap_func;
  112 
  113 dtrace_doubletrap_func_t        dtrace_doubletrap_func;
  114 
  115 /*
  116  * This is a hook which is initialised by the systrace module
  117  * when it is loaded. This keeps the DTrace syscall provider
  118  * implementation opaque. 
  119  */
  120 systrace_probe_func_t   systrace_probe_func;
  121 
  122 /*
  123  * These hooks are necessary for the pid, usdt and fasttrap providers.
  124  */
  125 dtrace_fasttrap_probe_ptr_t     dtrace_fasttrap_probe_ptr;
  126 dtrace_pid_probe_ptr_t          dtrace_pid_probe_ptr;
  127 dtrace_return_probe_ptr_t       dtrace_return_probe_ptr;
  128 #endif
  129 
  130 extern void trap(struct trapframe *frame);
  131 extern void syscall(struct trapframe *frame);
  132 
  133 static int trap_pfault(struct trapframe *, int, vm_offset_t);
  134 static void trap_fatal(struct trapframe *, vm_offset_t);
  135 void dblfault_handler(void);
  136 
  137 extern inthand_t IDTVEC(lcall_syscall);
  138 
  139 #define MAX_TRAP_MSG            33
  140 static char *trap_msg[] = {
  141         "",                                     /*  0 unused */
  142         "privileged instruction fault",         /*  1 T_PRIVINFLT */
  143         "",                                     /*  2 unused */
  144         "breakpoint instruction fault",         /*  3 T_BPTFLT */
  145         "",                                     /*  4 unused */
  146         "",                                     /*  5 unused */
  147         "arithmetic trap",                      /*  6 T_ARITHTRAP */
  148         "",                                     /*  7 unused */
  149         "",                                     /*  8 unused */
  150         "general protection fault",             /*  9 T_PROTFLT */
  151         "trace trap",                           /* 10 T_TRCTRAP */
  152         "",                                     /* 11 unused */
  153         "page fault",                           /* 12 T_PAGEFLT */
  154         "",                                     /* 13 unused */
  155         "alignment fault",                      /* 14 T_ALIGNFLT */
  156         "",                                     /* 15 unused */
  157         "",                                     /* 16 unused */
  158         "",                                     /* 17 unused */
  159         "integer divide fault",                 /* 18 T_DIVIDE */
  160         "non-maskable interrupt trap",          /* 19 T_NMI */
  161         "overflow trap",                        /* 20 T_OFLOW */
  162         "FPU bounds check fault",               /* 21 T_BOUND */
  163         "FPU device not available",             /* 22 T_DNA */
  164         "double fault",                         /* 23 T_DOUBLEFLT */
  165         "FPU operand fetch fault",              /* 24 T_FPOPFLT */
  166         "invalid TSS fault",                    /* 25 T_TSSFLT */
  167         "segment not present fault",            /* 26 T_SEGNPFLT */
  168         "stack fault",                          /* 27 T_STKFLT */
  169         "machine check trap",                   /* 28 T_MCHK */
  170         "SIMD floating-point exception",        /* 29 T_XMMFLT */
  171         "reserved (unknown) fault",             /* 30 T_RESERVED */
  172         "",                                     /* 31 unused (reserved) */
  173         "DTrace pid return trap",               /* 32 T_DTRACE_RET */
  174         "DTrace fasttrap probe trap",           /* 33 T_DTRACE_PROBE */
  175 
  176 };
  177 
  178 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
  179 extern int has_f00f_bug;
  180 #endif
  181 
  182 #ifdef KDB
  183 static int kdb_on_nmi = 1;
  184 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW,
  185         &kdb_on_nmi, 0, "Go to KDB on NMI");
  186 TUNABLE_INT("machdep.kdb_on_nmi", &kdb_on_nmi);
  187 #endif
  188 static int panic_on_nmi = 1;
  189 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW,
  190         &panic_on_nmi, 0, "Panic on NMI");
  191 TUNABLE_INT("machdep.panic_on_nmi", &panic_on_nmi);
  192 static int prot_fault_translation = 0;
  193 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RW,
  194         &prot_fault_translation, 0, "Select signal to deliver on protection fault");
  195 
  196 /*
  197  * Exception, fault, and trap interface to the FreeBSD kernel.
  198  * This common code is called from assembly language IDT gate entry
  199  * routines that prepare a suitable stack frame, and restore this
  200  * frame after the exception has been processed.
  201  */
  202 
  203 void
  204 trap(struct trapframe *frame)
  205 {
  206         struct thread *td = curthread;
  207         struct proc *p = td->td_proc;
  208         int i = 0, ucode = 0, code;
  209         u_int type;
  210         register_t addr = 0;
  211         vm_offset_t eva;
  212         ksiginfo_t ksi;
  213 #ifdef POWERFAIL_NMI
  214         static int lastalert = 0;
  215 #endif
  216 
  217         PCPU_INC(cnt.v_trap);
  218         type = frame->tf_trapno;
  219 
  220 #ifdef SMP
  221         /* Handler for NMI IPIs used for stopping CPUs. */
  222         if (type == T_NMI) {
  223                  if (ipi_nmi_handler() == 0)
  224                            goto out;
  225         }
  226 #endif /* SMP */
  227 
  228 #ifdef KDB
  229         if (kdb_active) {
  230                 kdb_reenter();
  231                 goto out;
  232         }
  233 #endif
  234 
  235         if (type == T_RESERVED) {
  236                 trap_fatal(frame, 0);
  237                 goto out;
  238         }
  239 
  240 #ifdef  HWPMC_HOOKS
  241         /*
  242          * CPU PMCs interrupt using an NMI so we check for that first.
  243          * If the HWPMC module is active, 'pmc_hook' will point to
  244          * the function to be called.  A return value of '1' from the
  245          * hook means that the NMI was handled by it and that we can
  246          * return immediately.
  247          */
  248         if (type == T_NMI && pmc_intr &&
  249             (*pmc_intr)(PCPU_GET(cpuid), frame))
  250             goto out;
  251 #endif
  252 
  253         if (type == T_MCHK) {
  254                 if (!mca_intr())
  255                         trap_fatal(frame, 0);
  256                 goto out;
  257         }
  258 
  259 #ifdef KDTRACE_HOOKS
  260         /*
  261          * A trap can occur while DTrace executes a probe. Before
  262          * executing the probe, DTrace blocks re-scheduling and sets
  263          * a flag in it's per-cpu flags to indicate that it doesn't
  264          * want to fault. On returning from the probe, the no-fault
  265          * flag is cleared and finally re-scheduling is enabled.
  266          *
  267          * If the DTrace kernel module has registered a trap handler,
  268          * call it and if it returns non-zero, assume that it has
  269          * handled the trap and modified the trap frame so that this
  270          * function can return normally.
  271          */
  272         if (type == T_DTRACE_PROBE || type == T_DTRACE_RET ||
  273             type == T_BPTFLT) {
  274                 struct reg regs;
  275 
  276                 fill_frame_regs(frame, &regs);
  277                 if (type == T_DTRACE_PROBE &&
  278                     dtrace_fasttrap_probe_ptr != NULL &&
  279                     dtrace_fasttrap_probe_ptr(&regs) == 0)
  280                         goto out;
  281                 if (type == T_BPTFLT &&
  282                     dtrace_pid_probe_ptr != NULL &&
  283                     dtrace_pid_probe_ptr(&regs) == 0)
  284                         goto out;
  285                 if (type == T_DTRACE_RET &&
  286                     dtrace_return_probe_ptr != NULL &&
  287                     dtrace_return_probe_ptr(&regs) == 0)
  288                         goto out;
  289         }
  290         if ((type == T_PROTFLT || type == T_PAGEFLT) &&
  291             dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type))
  292                 goto out;
  293 #endif
  294 
  295         if ((frame->tf_eflags & PSL_I) == 0) {
  296                 /*
  297                  * Buggy application or kernel code has disabled
  298                  * interrupts and then trapped.  Enabling interrupts
  299                  * now is wrong, but it is better than running with
  300                  * interrupts disabled until they are accidentally
  301                  * enabled later.
  302                  */
  303                 if (ISPL(frame->tf_cs) == SEL_UPL || (frame->tf_eflags & PSL_VM))
  304                         uprintf(
  305                             "pid %ld (%s): trap %d with interrupts disabled\n",
  306                             (long)curproc->p_pid, curthread->td_name, type);
  307                 else if (type != T_BPTFLT && type != T_TRCTRAP &&
  308                          frame->tf_eip != (int)cpu_switch_load_gs) {
  309                         /*
  310                          * XXX not quite right, since this may be for a
  311                          * multiple fault in user mode.
  312                          */
  313                         printf("kernel trap %d with interrupts disabled\n",
  314                             type);
  315                         /*
  316                          * Page faults need interrupts disabled until later,
  317                          * and we shouldn't enable interrupts while holding
  318                          * a spin lock or if servicing an NMI.
  319                          */
  320                         if (type != T_NMI && type != T_PAGEFLT &&
  321                             td->td_md.md_spinlock_count == 0)
  322                                 enable_intr();
  323                 }
  324         }
  325         eva = 0;
  326         code = frame->tf_err;
  327         if (type == T_PAGEFLT) {
  328                 /*
  329                  * For some Cyrix CPUs, %cr2 is clobbered by
  330                  * interrupts.  This problem is worked around by using
  331                  * an interrupt gate for the pagefault handler.  We
  332                  * are finally ready to read %cr2 and then must
  333                  * reenable interrupts.
  334                  *
  335                  * If we get a page fault while in a critical section, then
  336                  * it is most likely a fatal kernel page fault.  The kernel
  337                  * is already going to panic trying to get a sleep lock to
  338                  * do the VM lookup, so just consider it a fatal trap so the
  339                  * kernel can print out a useful trap message and even get
  340                  * to the debugger.
  341                  *
  342                  * If we get a page fault while holding a non-sleepable
  343                  * lock, then it is most likely a fatal kernel page fault.
  344                  * If WITNESS is enabled, then it's going to whine about
  345                  * bogus LORs with various VM locks, so just skip to the
  346                  * fatal trap handling directly.
  347                  */
  348                 eva = rcr2();
  349                 if (td->td_critnest != 0 ||
  350                     WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL,
  351                     "Kernel page fault") != 0)
  352                         trap_fatal(frame, eva);
  353                 else
  354                         enable_intr();
  355         }
  356 
  357         if ((ISPL(frame->tf_cs) == SEL_UPL) ||
  358             ((frame->tf_eflags & PSL_VM) && 
  359                 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) {
  360                 /* user trap */
  361 
  362                 td->td_pticks = 0;
  363                 td->td_frame = frame;
  364                 addr = frame->tf_eip;
  365                 if (td->td_ucred != p->p_ucred) 
  366                         cred_update_thread(td);
  367 
  368                 switch (type) {
  369                 case T_PRIVINFLT:       /* privileged instruction fault */
  370                         i = SIGILL;
  371                         ucode = ILL_PRVOPC;
  372                         break;
  373 
  374                 case T_BPTFLT:          /* bpt instruction fault */
  375                 case T_TRCTRAP:         /* trace trap */
  376                         enable_intr();
  377                         frame->tf_eflags &= ~PSL_T;
  378                         i = SIGTRAP;
  379                         ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
  380                         break;
  381 
  382                 case T_ARITHTRAP:       /* arithmetic trap */
  383 #ifdef DEV_NPX
  384                         ucode = npxtrap();
  385                         if (ucode == -1)
  386                                 goto userout;
  387 #else
  388                         ucode = 0;
  389 #endif
  390                         i = SIGFPE;
  391                         break;
  392 
  393                         /*
  394                          * The following two traps can happen in
  395                          * vm86 mode, and, if so, we want to handle
  396                          * them specially.
  397                          */
  398                 case T_PROTFLT:         /* general protection fault */
  399                 case T_STKFLT:          /* stack fault */
  400                         if (frame->tf_eflags & PSL_VM) {
  401                                 i = vm86_emulate((struct vm86frame *)frame);
  402                                 if (i == 0)
  403                                         goto user;
  404                                 break;
  405                         }
  406                         i = SIGBUS;
  407                         ucode = (type == T_PROTFLT) ? BUS_OBJERR : BUS_ADRERR;
  408                         break;
  409                 case T_SEGNPFLT:        /* segment not present fault */
  410                         i = SIGBUS;
  411                         ucode = BUS_ADRERR;
  412                         break;
  413                 case T_TSSFLT:          /* invalid TSS fault */
  414                         i = SIGBUS;
  415                         ucode = BUS_OBJERR;
  416                         break;
  417                 case T_DOUBLEFLT:       /* double fault */
  418                 default:
  419                         i = SIGBUS;
  420                         ucode = BUS_OBJERR;
  421                         break;
  422 
  423                 case T_PAGEFLT:         /* page fault */
  424 
  425                         i = trap_pfault(frame, TRUE, eva);
  426 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
  427                         if (i == -2) {
  428                                 /*
  429                                  * The f00f hack workaround has triggered, so
  430                                  * treat the fault as an illegal instruction 
  431                                  * (T_PRIVINFLT) instead of a page fault.
  432                                  */
  433                                 type = frame->tf_trapno = T_PRIVINFLT;
  434 
  435                                 /* Proceed as in that case. */
  436                                 ucode = ILL_PRVOPC;
  437                                 i = SIGILL;
  438                                 break;
  439                         }
  440 #endif
  441                         if (i == -1)
  442                                 goto userout;
  443                         if (i == 0)
  444                                 goto user;
  445 
  446                         if (i == SIGSEGV)
  447                                 ucode = SEGV_MAPERR;
  448                         else {
  449                                 if (prot_fault_translation == 0) {
  450                                         /*
  451                                          * Autodetect.
  452                                          * This check also covers the images
  453                                          * without the ABI-tag ELF note.
  454                                          */
  455                                         if (SV_CURPROC_ABI() == SV_ABI_FREEBSD
  456                                             && p->p_osrel >= P_OSREL_SIGSEGV) {
  457                                                 i = SIGSEGV;
  458                                                 ucode = SEGV_ACCERR;
  459                                         } else {
  460                                                 i = SIGBUS;
  461                                                 ucode = BUS_PAGE_FAULT;
  462                                         }
  463                                 } else if (prot_fault_translation == 1) {
  464                                         /*
  465                                          * Always compat mode.
  466                                          */
  467                                         i = SIGBUS;
  468                                         ucode = BUS_PAGE_FAULT;
  469                                 } else {
  470                                         /*
  471                                          * Always SIGSEGV mode.
  472                                          */
  473                                         i = SIGSEGV;
  474                                         ucode = SEGV_ACCERR;
  475                                 }
  476                         }
  477                         addr = eva;
  478                         break;
  479 
  480                 case T_DIVIDE:          /* integer divide fault */
  481                         ucode = FPE_INTDIV;
  482                         i = SIGFPE;
  483                         break;
  484 
  485 #ifdef DEV_ISA
  486                 case T_NMI:
  487 #ifdef POWERFAIL_NMI
  488 #ifndef TIMER_FREQ
  489 #  define TIMER_FREQ 1193182
  490 #endif
  491                         if (time_second - lastalert > 10) {
  492                                 log(LOG_WARNING, "NMI: power fail\n");
  493                                 sysbeep(880, hz);
  494                                 lastalert = time_second;
  495                         }
  496                         goto userout;
  497 #else /* !POWERFAIL_NMI */
  498                         /* machine/parity/power fail/"kitchen sink" faults */
  499                         if (isa_nmi(code) == 0) {
  500 #ifdef KDB
  501                                 /*
  502                                  * NMI can be hooked up to a pushbutton
  503                                  * for debugging.
  504                                  */
  505                                 if (kdb_on_nmi) {
  506                                         printf ("NMI ... going to debugger\n");
  507                                         kdb_trap(type, 0, frame);
  508                                 }
  509 #endif /* KDB */
  510                                 goto userout;
  511                         } else if (panic_on_nmi)
  512                                 panic("NMI indicates hardware failure");
  513                         break;
  514 #endif /* POWERFAIL_NMI */
  515 #endif /* DEV_ISA */
  516 
  517                 case T_OFLOW:           /* integer overflow fault */
  518                         ucode = FPE_INTOVF;
  519                         i = SIGFPE;
  520                         break;
  521 
  522                 case T_BOUND:           /* bounds check fault */
  523                         ucode = FPE_FLTSUB;
  524                         i = SIGFPE;
  525                         break;
  526 
  527                 case T_DNA:
  528 #ifdef DEV_NPX
  529                         KASSERT(PCB_USER_FPU(td->td_pcb),
  530                             ("kernel FPU ctx has leaked"));
  531                         /* transparent fault (due to context switch "late") */
  532                         if (npxdna())
  533                                 goto userout;
  534 #endif
  535                         uprintf("pid %d killed due to lack of floating point\n",
  536                                 p->p_pid);
  537                         i = SIGKILL;
  538                         ucode = 0;
  539                         break;
  540 
  541                 case T_FPOPFLT:         /* FPU operand fetch fault */
  542                         ucode = ILL_COPROC;
  543                         i = SIGILL;
  544                         break;
  545 
  546                 case T_XMMFLT:          /* SIMD floating-point exception */
  547                         ucode = 0; /* XXX */
  548                         i = SIGFPE;
  549                         break;
  550                 }
  551         } else {
  552                 /* kernel trap */
  553 
  554                 KASSERT(cold || td->td_ucred != NULL,
  555                     ("kernel trap doesn't have ucred"));
  556                 switch (type) {
  557                 case T_PAGEFLT:                 /* page fault */
  558                         (void) trap_pfault(frame, FALSE, eva);
  559                         goto out;
  560 
  561                 case T_DNA:
  562 #ifdef DEV_NPX
  563                         KASSERT(!PCB_USER_FPU(td->td_pcb),
  564                             ("Unregistered use of FPU in kernel"));
  565                         if (npxdna())
  566                                 goto out;
  567 #endif
  568                         break;
  569 
  570                 case T_ARITHTRAP:       /* arithmetic trap */
  571                 case T_XMMFLT:          /* SIMD floating-point exception */
  572                 case T_FPOPFLT:         /* FPU operand fetch fault */
  573                         /*
  574                          * XXXKIB for now disable any FPU traps in kernel
  575                          * handler registration seems to be overkill
  576                          */
  577                         trap_fatal(frame, 0);
  578                         goto out;
  579 
  580                         /*
  581                          * The following two traps can happen in
  582                          * vm86 mode, and, if so, we want to handle
  583                          * them specially.
  584                          */
  585                 case T_PROTFLT:         /* general protection fault */
  586                 case T_STKFLT:          /* stack fault */
  587                         if (frame->tf_eflags & PSL_VM) {
  588                                 i = vm86_emulate((struct vm86frame *)frame);
  589                                 if (i != 0)
  590                                         /*
  591                                          * returns to original process
  592                                          */
  593                                         vm86_trap((struct vm86frame *)frame);
  594                                 goto out;
  595                         }
  596                         if (type == T_STKFLT)
  597                                 break;
  598 
  599                         /* FALL THROUGH */
  600 
  601                 case T_SEGNPFLT:        /* segment not present fault */
  602                         if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)
  603                                 break;
  604 
  605                         /*
  606                          * Invalid %fs's and %gs's can be created using
  607                          * procfs or PT_SETREGS or by invalidating the
  608                          * underlying LDT entry.  This causes a fault
  609                          * in kernel mode when the kernel attempts to
  610                          * switch contexts.  Lose the bad context
  611                          * (XXX) so that we can continue, and generate
  612                          * a signal.
  613                          */
  614                         if (frame->tf_eip == (int)cpu_switch_load_gs) {
  615                                 PCPU_GET(curpcb)->pcb_gs = 0;
  616 #if 0                           
  617                                 PROC_LOCK(p);
  618                                 kern_psignal(p, SIGBUS);
  619                                 PROC_UNLOCK(p);
  620 #endif                          
  621                                 goto out;
  622                         }
  623 
  624                         if (td->td_intr_nesting_level != 0)
  625                                 break;
  626 
  627                         /*
  628                          * Invalid segment selectors and out of bounds
  629                          * %eip's and %esp's can be set up in user mode.
  630                          * This causes a fault in kernel mode when the
  631                          * kernel tries to return to user mode.  We want
  632                          * to get this fault so that we can fix the
  633                          * problem here and not have to check all the
  634                          * selectors and pointers when the user changes
  635                          * them.
  636                          */
  637                         if (frame->tf_eip == (int)doreti_iret) {
  638                                 frame->tf_eip = (int)doreti_iret_fault;
  639                                 goto out;
  640                         }
  641                         if (frame->tf_eip == (int)doreti_popl_ds) {
  642                                 frame->tf_eip = (int)doreti_popl_ds_fault;
  643                                 goto out;
  644                         }
  645                         if (frame->tf_eip == (int)doreti_popl_es) {
  646                                 frame->tf_eip = (int)doreti_popl_es_fault;
  647                                 goto out;
  648                         }
  649                         if (frame->tf_eip == (int)doreti_popl_fs) {
  650                                 frame->tf_eip = (int)doreti_popl_fs_fault;
  651                                 goto out;
  652                         }
  653                         if (PCPU_GET(curpcb)->pcb_onfault != NULL) {
  654                                 frame->tf_eip =
  655                                     (int)PCPU_GET(curpcb)->pcb_onfault;
  656                                 goto out;
  657                         }
  658                         break;
  659 
  660                 case T_TSSFLT:
  661                         /*
  662                          * PSL_NT can be set in user mode and isn't cleared
  663                          * automatically when the kernel is entered.  This
  664                          * causes a TSS fault when the kernel attempts to
  665                          * `iret' because the TSS link is uninitialized.  We
  666                          * want to get this fault so that we can fix the
  667                          * problem here and not every time the kernel is
  668                          * entered.
  669                          */
  670                         if (frame->tf_eflags & PSL_NT) {
  671                                 frame->tf_eflags &= ~PSL_NT;
  672                                 goto out;
  673                         }
  674                         break;
  675 
  676                 case T_TRCTRAP:  /* trace trap */
  677                         if (frame->tf_eip == (int)IDTVEC(lcall_syscall)) {
  678                                 /*
  679                                  * We've just entered system mode via the
  680                                  * syscall lcall.  Continue single stepping
  681                                  * silently until the syscall handler has
  682                                  * saved the flags.
  683                                  */
  684                                 goto out;
  685                         }
  686                         if (frame->tf_eip == (int)IDTVEC(lcall_syscall) + 1) {
  687                                 /*
  688                                  * The syscall handler has now saved the
  689                                  * flags.  Stop single stepping it.
  690                                  */
  691                                 frame->tf_eflags &= ~PSL_T;
  692                                 goto out;
  693                         }
  694                         /*
  695                          * Ignore debug register trace traps due to
  696                          * accesses in the user's address space, which
  697                          * can happen under several conditions such as
  698                          * if a user sets a watchpoint on a buffer and
  699                          * then passes that buffer to a system call.
  700                          * We still want to get TRCTRAPS for addresses
  701                          * in kernel space because that is useful when
  702                          * debugging the kernel.
  703                          */
  704                         if (user_dbreg_trap() && 
  705                            !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)) {
  706                                 /*
  707                                  * Reset breakpoint bits because the
  708                                  * processor doesn't
  709                                  */
  710                                 load_dr6(rdr6() & 0xfffffff0);
  711                                 goto out;
  712                         }
  713                         /*
  714                          * FALLTHROUGH (TRCTRAP kernel mode, kernel address)
  715                          */
  716                 case T_BPTFLT:
  717                         /*
  718                          * If KDB is enabled, let it handle the debugger trap.
  719                          * Otherwise, debugger traps "can't happen".
  720                          */
  721 #ifdef KDB
  722                         if (kdb_trap(type, 0, frame))
  723                                 goto out;
  724 #endif
  725                         break;
  726 
  727 #ifdef DEV_ISA
  728                 case T_NMI:
  729 #ifdef POWERFAIL_NMI
  730                         if (time_second - lastalert > 10) {
  731                                 log(LOG_WARNING, "NMI: power fail\n");
  732                                 sysbeep(880, hz);
  733                                 lastalert = time_second;
  734                         }
  735                         goto out;
  736 #else /* !POWERFAIL_NMI */
  737                         /* machine/parity/power fail/"kitchen sink" faults */
  738                         if (isa_nmi(code) == 0) {
  739 #ifdef KDB
  740                                 /*
  741                                  * NMI can be hooked up to a pushbutton
  742                                  * for debugging.
  743                                  */
  744                                 if (kdb_on_nmi) {
  745                                         printf ("NMI ... going to debugger\n");
  746                                         kdb_trap(type, 0, frame);
  747                                 }
  748 #endif /* KDB */
  749                                 goto out;
  750                         } else if (panic_on_nmi == 0)
  751                                 goto out;
  752                         /* FALLTHROUGH */
  753 #endif /* POWERFAIL_NMI */
  754 #endif /* DEV_ISA */
  755                 }
  756 
  757                 trap_fatal(frame, eva);
  758                 goto out;
  759         }
  760 
  761         /* Translate fault for emulators (e.g. Linux) */
  762         if (*p->p_sysent->sv_transtrap)
  763                 i = (*p->p_sysent->sv_transtrap)(i, type);
  764 
  765         ksiginfo_init_trap(&ksi);
  766         ksi.ksi_signo = i;
  767         ksi.ksi_code = ucode;
  768         ksi.ksi_addr = (void *)addr;
  769         ksi.ksi_trapno = type;
  770         trapsignal(td, &ksi);
  771 
  772 #ifdef DEBUG
  773         if (type <= MAX_TRAP_MSG) {
  774                 uprintf("fatal process exception: %s",
  775                         trap_msg[type]);
  776                 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
  777                         uprintf(", fault VA = 0x%lx", (u_long)eva);
  778                 uprintf("\n");
  779         }
  780 #endif
  781 
  782 user:
  783         userret(td, frame);
  784         mtx_assert(&Giant, MA_NOTOWNED);
  785         KASSERT(PCB_USER_FPU(td->td_pcb),
  786             ("Return from trap with kernel FPU ctx leaked"));
  787 userout:
  788 out:
  789         return;
  790 }
  791 
  792 static int
  793 trap_pfault(frame, usermode, eva)
  794         struct trapframe *frame;
  795         int usermode;
  796         vm_offset_t eva;
  797 {
  798         vm_offset_t va;
  799         struct vmspace *vm = NULL;
  800         vm_map_t map;
  801         int rv = 0;
  802         vm_prot_t ftype;
  803         struct thread *td = curthread;
  804         struct proc *p = td->td_proc;
  805 
  806         va = trunc_page(eva);
  807         if (va >= KERNBASE) {
  808                 /*
  809                  * Don't allow user-mode faults in kernel address space.
  810                  * An exception:  if the faulting address is the invalid
  811                  * instruction entry in the IDT, then the Intel Pentium
  812                  * F00F bug workaround was triggered, and we need to
  813                  * treat it is as an illegal instruction, and not a page
  814                  * fault.
  815                  */
  816 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
  817                 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug)
  818                         return -2;
  819 #endif
  820                 if (usermode)
  821                         goto nogo;
  822 
  823                 map = kernel_map;
  824         } else {
  825                 /*
  826                  * This is a fault on non-kernel virtual memory.
  827                  * vm is initialized above to NULL. If curproc is NULL
  828                  * or curproc->p_vmspace is NULL the fault is fatal.
  829                  */
  830                 if (p != NULL)
  831                         vm = p->p_vmspace;
  832 
  833                 if (vm == NULL)
  834                         goto nogo;
  835 
  836                 map = &vm->vm_map;
  837                 if (!usermode && (td->td_intr_nesting_level != 0 ||
  838                     PCPU_GET(curpcb)->pcb_onfault == NULL)) {
  839                         trap_fatal(frame, eva);
  840                         return (-1);
  841                 }
  842         }
  843 
  844         /*
  845          * PGEX_I is defined only if the execute disable bit capability is
  846          * supported and enabled.
  847          */
  848         if (frame->tf_err & PGEX_W)
  849                 ftype = VM_PROT_WRITE;
  850 #ifdef PAE
  851         else if ((frame->tf_err & PGEX_I) && pg_nx != 0)
  852                 ftype = VM_PROT_EXECUTE;
  853 #endif
  854         else
  855                 ftype = VM_PROT_READ;
  856 
  857         if (map != kernel_map) {
  858                 /*
  859                  * Keep swapout from messing with us during this
  860                  *      critical time.
  861                  */
  862                 PROC_LOCK(p);
  863                 ++p->p_lock;
  864                 PROC_UNLOCK(p);
  865 
  866                 /* Fault in the user page: */
  867                 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
  868 
  869                 PROC_LOCK(p);
  870                 --p->p_lock;
  871                 PROC_UNLOCK(p);
  872         } else {
  873                 /*
  874                  * Don't have to worry about process locking or stacks in the
  875                  * kernel.
  876                  */
  877                 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
  878         }
  879         if (rv == KERN_SUCCESS)
  880                 return (0);
  881 nogo:
  882         if (!usermode) {
  883                 if (td->td_intr_nesting_level == 0 &&
  884                     PCPU_GET(curpcb)->pcb_onfault != NULL) {
  885                         frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault;
  886                         return (0);
  887                 }
  888                 trap_fatal(frame, eva);
  889                 return (-1);
  890         }
  891 
  892         return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
  893 }
  894 
  895 static void
  896 trap_fatal(frame, eva)
  897         struct trapframe *frame;
  898         vm_offset_t eva;
  899 {
  900         int code, ss, esp;
  901         u_int type;
  902         struct soft_segment_descriptor softseg;
  903         char *msg;
  904 
  905         code = frame->tf_err;
  906         type = frame->tf_trapno;
  907         sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg);
  908 
  909         if (type <= MAX_TRAP_MSG)
  910                 msg = trap_msg[type];
  911         else
  912                 msg = "UNKNOWN";
  913         printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg,
  914             frame->tf_eflags & PSL_VM ? "vm86" :
  915             ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel");
  916 #ifdef SMP
  917         /* two separate prints in case of a trap on an unmapped page */
  918         printf("cpuid = %d; ", PCPU_GET(cpuid));
  919         printf("apic id = %02x\n", PCPU_GET(apic_id));
  920 #endif
  921         if (type == T_PAGEFLT) {
  922                 printf("fault virtual address   = 0x%x\n", eva);
  923                 printf("fault code              = %s %s, %s\n",
  924                         code & PGEX_U ? "user" : "supervisor",
  925                         code & PGEX_W ? "write" : "read",
  926                         code & PGEX_P ? "protection violation" : "page not present");
  927         }
  928         printf("instruction pointer     = 0x%x:0x%x\n",
  929                frame->tf_cs & 0xffff, frame->tf_eip);
  930         if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) {
  931                 ss = frame->tf_ss & 0xffff;
  932                 esp = frame->tf_esp;
  933         } else {
  934                 ss = GSEL(GDATA_SEL, SEL_KPL);
  935                 esp = (int)&frame->tf_esp;
  936         }
  937         printf("stack pointer           = 0x%x:0x%x\n", ss, esp);
  938         printf("frame pointer           = 0x%x:0x%x\n", ss, frame->tf_ebp);
  939         printf("code segment            = base 0x%x, limit 0x%x, type 0x%x\n",
  940                softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type);
  941         printf("                        = DPL %d, pres %d, def32 %d, gran %d\n",
  942                softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32,
  943                softseg.ssd_gran);
  944         printf("processor eflags        = ");
  945         if (frame->tf_eflags & PSL_T)
  946                 printf("trace trap, ");
  947         if (frame->tf_eflags & PSL_I)
  948                 printf("interrupt enabled, ");
  949         if (frame->tf_eflags & PSL_NT)
  950                 printf("nested task, ");
  951         if (frame->tf_eflags & PSL_RF)
  952                 printf("resume, ");
  953         if (frame->tf_eflags & PSL_VM)
  954                 printf("vm86, ");
  955         printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12);
  956         printf("current process         = ");
  957         if (curproc) {
  958                 printf("%lu (%s)\n", (u_long)curproc->p_pid, curthread->td_name);
  959         } else {
  960                 printf("Idle\n");
  961         }
  962 
  963 #ifdef KDB
  964         if (debugger_on_panic || kdb_active) {
  965                 frame->tf_err = eva;    /* smuggle fault address to ddb */
  966                 if (kdb_trap(type, 0, frame)) {
  967                         frame->tf_err = code;   /* restore error code */
  968                         return;
  969                 }
  970                 frame->tf_err = code;           /* restore error code */
  971         }
  972 #endif
  973         printf("trap number             = %d\n", type);
  974         if (type <= MAX_TRAP_MSG)
  975                 panic("%s", trap_msg[type]);
  976         else
  977                 panic("unknown/reserved trap");
  978 }
  979 
  980 /*
  981  * Double fault handler. Called when a fault occurs while writing
  982  * a frame for a trap/exception onto the stack. This usually occurs
  983  * when the stack overflows (such is the case with infinite recursion,
  984  * for example).
  985  *
  986  * XXX Note that the current PTD gets replaced by IdlePTD when the
  987  * task switch occurs. This means that the stack that was active at
  988  * the time of the double fault is not available at <kstack> unless
  989  * the machine was idle when the double fault occurred. The downside
  990  * of this is that "trace <ebp>" in ddb won't work.
  991  */
  992 void
  993 dblfault_handler()
  994 {
  995 #ifdef KDTRACE_HOOKS
  996         if (dtrace_doubletrap_func != NULL)
  997                 (*dtrace_doubletrap_func)();
  998 #endif
  999         printf("\nFatal double fault:\n");
 1000         printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip));
 1001         printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp));
 1002         printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp));
 1003 #ifdef SMP
 1004         /* two separate prints in case of a trap on an unmapped page */
 1005         printf("cpuid = %d; ", PCPU_GET(cpuid));
 1006         printf("apic id = %02x\n", PCPU_GET(apic_id));
 1007 #endif
 1008         panic("double fault");
 1009 }
 1010 
 1011 int
 1012 cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 1013 {
 1014         struct proc *p;
 1015         struct trapframe *frame;
 1016         caddr_t params;
 1017         int error;
 1018 
 1019         p = td->td_proc;
 1020         frame = td->td_frame;
 1021 
 1022         params = (caddr_t)frame->tf_esp + sizeof(int);
 1023         sa->code = frame->tf_eax;
 1024 
 1025         /*
 1026          * Need to check if this is a 32 bit or 64 bit syscall.
 1027          */
 1028         if (sa->code == SYS_syscall) {
 1029                 /*
 1030                  * Code is first argument, followed by actual args.
 1031                  */
 1032                 sa->code = fuword(params);
 1033                 params += sizeof(int);
 1034         } else if (sa->code == SYS___syscall) {
 1035                 /*
 1036                  * Like syscall, but code is a quad, so as to maintain
 1037                  * quad alignment for the rest of the arguments.
 1038                  */
 1039                 sa->code = fuword(params);
 1040                 params += sizeof(quad_t);
 1041         }
 1042 
 1043         if (p->p_sysent->sv_mask)
 1044                 sa->code &= p->p_sysent->sv_mask;
 1045         if (sa->code >= p->p_sysent->sv_size)
 1046                 sa->callp = &p->p_sysent->sv_table[0];
 1047         else
 1048                 sa->callp = &p->p_sysent->sv_table[sa->code];
 1049         sa->narg = sa->callp->sy_narg;
 1050 
 1051         if (params != NULL && sa->narg != 0)
 1052                 error = copyin(params, (caddr_t)sa->args,
 1053                     (u_int)(sa->narg * sizeof(int)));
 1054         else
 1055                 error = 0;
 1056 
 1057         if (error == 0) {
 1058                 td->td_retval[0] = 0;
 1059                 td->td_retval[1] = frame->tf_edx;
 1060         }
 1061                 
 1062         return (error);
 1063 }
 1064 
 1065 #include "../../kern/subr_syscall.c"
 1066 
 1067 /*
 1068  *      syscall -       system call request C handler
 1069  *
 1070  *      A system call is essentially treated as a trap.
 1071  */
 1072 void
 1073 syscall(struct trapframe *frame)
 1074 {
 1075         struct thread *td;
 1076         struct syscall_args sa;
 1077         register_t orig_tf_eflags;
 1078         int error;
 1079         ksiginfo_t ksi;
 1080 
 1081 #ifdef DIAGNOSTIC
 1082         if (ISPL(frame->tf_cs) != SEL_UPL) {
 1083                 panic("syscall");
 1084                 /* NOT REACHED */
 1085         }
 1086 #endif
 1087         orig_tf_eflags = frame->tf_eflags;
 1088 
 1089         td = curthread;
 1090         td->td_frame = frame;
 1091 
 1092         error = syscallenter(td, &sa);
 1093 
 1094         /*
 1095          * Traced syscall.
 1096          */
 1097         if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) {
 1098                 frame->tf_eflags &= ~PSL_T;
 1099                 ksiginfo_init_trap(&ksi);
 1100                 ksi.ksi_signo = SIGTRAP;
 1101                 ksi.ksi_code = TRAP_TRACE;
 1102                 ksi.ksi_addr = (void *)frame->tf_eip;
 1103                 trapsignal(td, &ksi);
 1104         }
 1105 
 1106         KASSERT(PCB_USER_FPU(td->td_pcb),
 1107             ("System call %s returning with kernel FPU ctx leaked",
 1108              syscallname(td->td_proc, sa.code)));
 1109         KASSERT(td->td_pcb->pcb_save == &td->td_pcb->pcb_user_save,
 1110             ("System call %s returning with mangled pcb_save",
 1111              syscallname(td->td_proc, sa.code)));
 1112 
 1113         syscallret(td, error, &sa);
 1114 }

Cache object: f65573323c5529116dda4a55d545df4c


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