The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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/6.2/sys/i386/i386/trap.c 161901 2006-09-02 17:12:46Z rwatson $");
   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_ktrace.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 KTRACE
   75 #include <sys/ktrace.h>
   76 #endif
   77 #ifdef HWPMC_HOOKS
   78 #include <sys/pmckern.h>
   79 #endif
   80 #include <security/audit/audit.h>
   81 
   82 #include <vm/vm.h>
   83 #include <vm/vm_param.h>
   84 #include <vm/pmap.h>
   85 #include <vm/vm_kern.h>
   86 #include <vm/vm_map.h>
   87 #include <vm/vm_page.h>
   88 #include <vm/vm_extern.h>
   89 
   90 #include <machine/cpu.h>
   91 #include <machine/intr_machdep.h>
   92 #include <machine/md_var.h>
   93 #include <machine/pcb.h>
   94 #ifdef SMP
   95 #include <machine/smp.h>
   96 #endif
   97 #include <machine/tss.h>
   98 #include <machine/vm86.h>
   99 
  100 #ifdef POWERFAIL_NMI
  101 #include <sys/syslog.h>
  102 #include <machine/clock.h>
  103 #endif
  104 
  105 extern void trap(struct trapframe frame);
  106 extern void syscall(struct trapframe frame);
  107 
  108 static int trap_pfault(struct trapframe *, int, vm_offset_t);
  109 static void trap_fatal(struct trapframe *, vm_offset_t);
  110 void dblfault_handler(void);
  111 
  112 extern inthand_t IDTVEC(lcall_syscall);
  113 
  114 #define MAX_TRAP_MSG            30
  115 static char *trap_msg[] = {
  116         "",                                     /*  0 unused */
  117         "privileged instruction fault",         /*  1 T_PRIVINFLT */
  118         "",                                     /*  2 unused */
  119         "breakpoint instruction fault",         /*  3 T_BPTFLT */
  120         "",                                     /*  4 unused */
  121         "",                                     /*  5 unused */
  122         "arithmetic trap",                      /*  6 T_ARITHTRAP */
  123         "",                                     /*  7 unused */
  124         "",                                     /*  8 unused */
  125         "general protection fault",             /*  9 T_PROTFLT */
  126         "trace trap",                           /* 10 T_TRCTRAP */
  127         "",                                     /* 11 unused */
  128         "page fault",                           /* 12 T_PAGEFLT */
  129         "",                                     /* 13 unused */
  130         "alignment fault",                      /* 14 T_ALIGNFLT */
  131         "",                                     /* 15 unused */
  132         "",                                     /* 16 unused */
  133         "",                                     /* 17 unused */
  134         "integer divide fault",                 /* 18 T_DIVIDE */
  135         "non-maskable interrupt trap",          /* 19 T_NMI */
  136         "overflow trap",                        /* 20 T_OFLOW */
  137         "FPU bounds check fault",               /* 21 T_BOUND */
  138         "FPU device not available",             /* 22 T_DNA */
  139         "double fault",                         /* 23 T_DOUBLEFLT */
  140         "FPU operand fetch fault",              /* 24 T_FPOPFLT */
  141         "invalid TSS fault",                    /* 25 T_TSSFLT */
  142         "segment not present fault",            /* 26 T_SEGNPFLT */
  143         "stack fault",                          /* 27 T_STKFLT */
  144         "machine check trap",                   /* 28 T_MCHK */
  145         "SIMD floating-point exception",        /* 29 T_XMMFLT */
  146         "reserved (unknown) fault",             /* 30 T_RESERVED */
  147 };
  148 
  149 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
  150 extern int has_f00f_bug;
  151 #endif
  152 
  153 #ifdef KDB
  154 static int kdb_on_nmi = 1;
  155 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW,
  156         &kdb_on_nmi, 0, "Go to KDB on NMI");
  157 #endif
  158 static int panic_on_nmi = 1;
  159 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW,
  160         &panic_on_nmi, 0, "Panic on NMI");
  161 
  162 #ifdef WITNESS
  163 extern char *syscallnames[];
  164 #endif
  165 
  166 /*
  167  * Exception, fault, and trap interface to the FreeBSD kernel.
  168  * This common code is called from assembly language IDT gate entry
  169  * routines that prepare a suitable stack frame, and restore this
  170  * frame after the exception has been processed.
  171  */
  172 
  173 void
  174 trap(frame)
  175         struct trapframe frame;
  176 {
  177         struct thread *td = curthread;
  178         struct proc *p = td->td_proc;
  179         u_int sticks = 0;
  180         int i = 0, ucode = 0, type, code;
  181         vm_offset_t eva;
  182 #ifdef POWERFAIL_NMI
  183         static int lastalert = 0;
  184 #endif
  185 
  186         PCPU_LAZY_INC(cnt.v_trap);
  187         type = frame.tf_trapno;
  188 
  189 #ifdef KDB_STOP_NMI
  190         /* Handler for NMI IPIs used for debugging */
  191         if (type == T_NMI) {
  192                  if (ipi_nmi_handler() == 0)
  193                            goto out;
  194         }
  195 #endif /* KDB_STOP_NMI */
  196 
  197 #ifdef KDB
  198         if (kdb_active) {
  199                 kdb_reenter();
  200                 goto out;
  201         }
  202 #endif
  203 
  204 #ifdef  HWPMC_HOOKS
  205         /*
  206          * CPU PMCs interrupt using an NMI so we check for that first.
  207          * If the HWPMC module is active, 'pmc_hook' will point to
  208          * the function to be called.  A return value of '1' from the
  209          * hook means that the NMI was handled by it and that we can
  210          * return immediately.
  211          */
  212         if (type == T_NMI && pmc_intr &&
  213             (*pmc_intr)(PCPU_GET(cpuid), (uintptr_t) frame.tf_eip,
  214                 TRAPF_USERMODE(&frame)))
  215             goto out;
  216 #endif
  217 
  218         if ((frame.tf_eflags & PSL_I) == 0) {
  219                 /*
  220                  * Buggy application or kernel code has disabled
  221                  * interrupts and then trapped.  Enabling interrupts
  222                  * now is wrong, but it is better than running with
  223                  * interrupts disabled until they are accidentally
  224                  * enabled later.
  225                  */
  226                 if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM))
  227                         printf(
  228                             "pid %ld (%s): trap %d with interrupts disabled\n",
  229                             (long)curproc->p_pid, curproc->p_comm, type);
  230                 else if (type != T_BPTFLT && type != T_TRCTRAP &&
  231                          frame.tf_eip != (int)cpu_switch_load_gs) {
  232                         /*
  233                          * XXX not quite right, since this may be for a
  234                          * multiple fault in user mode.
  235                          */
  236                         printf("kernel trap %d with interrupts disabled\n",
  237                             type);
  238                         /*
  239                          * Page faults need interrupts disabled until later,
  240                          * and we shouldn't enable interrupts while in a
  241                          * critical section or if servicing an NMI.
  242                          */
  243                         if (type != T_NMI && type != T_PAGEFLT &&
  244                             td->td_critnest == 0)
  245                                 enable_intr();
  246                 }
  247         }
  248 
  249         eva = 0;
  250         code = frame.tf_err;
  251         if (type == T_PAGEFLT) {
  252                 /*
  253                  * For some Cyrix CPUs, %cr2 is clobbered by
  254                  * interrupts.  This problem is worked around by using
  255                  * an interrupt gate for the pagefault handler.  We
  256                  * are finally ready to read %cr2 and then must
  257                  * reenable interrupts.
  258                  *
  259                  * If we get a page fault while in a critical section, then
  260                  * it is most likely a fatal kernel page fault.  The kernel
  261                  * is already going to panic trying to get a sleep lock to
  262                  * do the VM lookup, so just consider it a fatal trap so the
  263                  * kernel can print out a useful trap message and even get
  264                  * to the debugger.
  265                  */
  266                 eva = rcr2();
  267                 if (td->td_critnest == 0)
  268                         enable_intr();
  269                 else
  270                         trap_fatal(&frame, eva);
  271         }
  272 
  273         if ((ISPL(frame.tf_cs) == SEL_UPL) ||
  274             ((frame.tf_eflags & PSL_VM) && 
  275                 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) {
  276                 /* user trap */
  277 
  278                 sticks = td->td_sticks;
  279                 td->td_frame = &frame;
  280                 if (td->td_ucred != p->p_ucred) 
  281                         cred_update_thread(td);
  282 
  283                 switch (type) {
  284                 case T_PRIVINFLT:       /* privileged instruction fault */
  285                         ucode = type;
  286                         i = SIGILL;
  287                         break;
  288 
  289                 case T_BPTFLT:          /* bpt instruction fault */
  290                 case T_TRCTRAP:         /* trace trap */
  291                         enable_intr();
  292                         frame.tf_eflags &= ~PSL_T;
  293                         i = SIGTRAP;
  294                         break;
  295 
  296                 case T_ARITHTRAP:       /* arithmetic trap */
  297 #ifdef DEV_NPX
  298                         ucode = npxtrap();
  299                         if (ucode == -1)
  300                                 goto userout;
  301 #else
  302                         ucode = code;
  303 #endif
  304                         i = SIGFPE;
  305                         break;
  306 
  307                         /*
  308                          * The following two traps can happen in
  309                          * vm86 mode, and, if so, we want to handle
  310                          * them specially.
  311                          */
  312                 case T_PROTFLT:         /* general protection fault */
  313                 case T_STKFLT:          /* stack fault */
  314                         if (frame.tf_eflags & PSL_VM) {
  315                                 i = vm86_emulate((struct vm86frame *)&frame);
  316                                 if (i == 0)
  317                                         goto user;
  318                                 break;
  319                         }
  320                         /* FALLTHROUGH */
  321 
  322                 case T_SEGNPFLT:        /* segment not present fault */
  323                 case T_TSSFLT:          /* invalid TSS fault */
  324                 case T_DOUBLEFLT:       /* double fault */
  325                 default:
  326                         ucode = code + BUS_SEGM_FAULT ;
  327                         i = SIGBUS;
  328                         break;
  329 
  330                 case T_PAGEFLT:         /* page fault */
  331                         if (td->td_pflags & TDP_SA)
  332                                 thread_user_enter(td);
  333 
  334                         i = trap_pfault(&frame, TRUE, eva);
  335 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
  336                         if (i == -2) {
  337                                 /*
  338                                  * The f00f hack workaround has triggered, so
  339                                  * treat the fault as an illegal instruction 
  340                                  * (T_PRIVINFLT) instead of a page fault.
  341                                  */
  342                                 type = frame.tf_trapno = T_PRIVINFLT;
  343 
  344                                 /* Proceed as in that case. */
  345                                 ucode = type;
  346                                 i = SIGILL;
  347                                 break;
  348                         }
  349 #endif
  350                         if (i == -1)
  351                                 goto userout;
  352                         if (i == 0)
  353                                 goto user;
  354 
  355                         ucode = T_PAGEFLT;
  356                         break;
  357 
  358                 case T_DIVIDE:          /* integer divide fault */
  359                         ucode = FPE_INTDIV;
  360                         i = SIGFPE;
  361                         break;
  362 
  363 #ifdef DEV_ISA
  364                 case T_NMI:
  365 #ifdef POWERFAIL_NMI
  366 #ifndef TIMER_FREQ
  367 #  define TIMER_FREQ 1193182
  368 #endif
  369                         mtx_lock(&Giant);
  370                         if (time_second - lastalert > 10) {
  371                                 log(LOG_WARNING, "NMI: power fail\n");
  372                                 sysbeep(TIMER_FREQ/880, hz);
  373                                 lastalert = time_second;
  374                         }
  375                         mtx_unlock(&Giant);
  376                         goto userout;
  377 #else /* !POWERFAIL_NMI */
  378                         /* machine/parity/power fail/"kitchen sink" faults */
  379                         /* XXX Giant */
  380                         if (isa_nmi(code) == 0) {
  381 #ifdef KDB
  382                                 /*
  383                                  * NMI can be hooked up to a pushbutton
  384                                  * for debugging.
  385                                  */
  386                                 if (kdb_on_nmi) {
  387                                         printf ("NMI ... going to debugger\n");
  388                                         kdb_trap(type, 0, &frame);
  389                                 }
  390 #endif /* KDB */
  391                                 goto userout;
  392                         } else if (panic_on_nmi)
  393                                 panic("NMI indicates hardware failure");
  394                         break;
  395 #endif /* POWERFAIL_NMI */
  396 #endif /* DEV_ISA */
  397 
  398                 case T_OFLOW:           /* integer overflow fault */
  399                         ucode = FPE_INTOVF;
  400                         i = SIGFPE;
  401                         break;
  402 
  403                 case T_BOUND:           /* bounds check fault */
  404                         ucode = FPE_FLTSUB;
  405                         i = SIGFPE;
  406                         break;
  407 
  408                 case T_DNA:
  409 #ifdef DEV_NPX
  410                         /* transparent fault (due to context switch "late") */
  411                         if (npxdna())
  412                                 goto userout;
  413 #endif
  414                         i = SIGFPE;
  415                         ucode = FPE_FPU_NP_TRAP;
  416                         break;
  417 
  418                 case T_FPOPFLT:         /* FPU operand fetch fault */
  419                         ucode = T_FPOPFLT;
  420                         i = SIGILL;
  421                         break;
  422 
  423                 case T_XMMFLT:          /* SIMD floating-point exception */
  424                         ucode = 0; /* XXX */
  425                         i = SIGFPE;
  426                         break;
  427                 }
  428         } else {
  429                 /* kernel trap */
  430 
  431                 KASSERT(cold || td->td_ucred != NULL,
  432                     ("kernel trap doesn't have ucred"));
  433                 switch (type) {
  434                 case T_PAGEFLT:                 /* page fault */
  435                         (void) trap_pfault(&frame, FALSE, eva);
  436                         goto out;
  437 
  438                 case T_DNA:
  439 #ifdef DEV_NPX
  440                         /*
  441                          * The kernel is apparently using npx for copying.
  442                          * XXX this should be fatal unless the kernel has
  443                          * registered such use.
  444                          */
  445                         if (npxdna())
  446                                 goto out;
  447 #endif
  448                         break;
  449 
  450                         /*
  451                          * The following two traps can happen in
  452                          * vm86 mode, and, if so, we want to handle
  453                          * them specially.
  454                          */
  455                 case T_PROTFLT:         /* general protection fault */
  456                 case T_STKFLT:          /* stack fault */
  457                         if (frame.tf_eflags & PSL_VM) {
  458                                 i = vm86_emulate((struct vm86frame *)&frame);
  459                                 if (i != 0)
  460                                         /*
  461                                          * returns to original process
  462                                          */
  463                                         vm86_trap((struct vm86frame *)&frame);
  464                                 goto out;
  465                         }
  466                         if (type == T_STKFLT)
  467                                 break;
  468 
  469                         /* FALL THROUGH */
  470 
  471                 case T_SEGNPFLT:        /* segment not present fault */
  472                         if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)
  473                                 break;
  474 
  475                         /*
  476                          * Invalid %fs's and %gs's can be created using
  477                          * procfs or PT_SETREGS or by invalidating the
  478                          * underlying LDT entry.  This causes a fault
  479                          * in kernel mode when the kernel attempts to
  480                          * switch contexts.  Lose the bad context
  481                          * (XXX) so that we can continue, and generate
  482                          * a signal.
  483                          */
  484                         if (frame.tf_eip == (int)cpu_switch_load_gs) {
  485                                 PCPU_GET(curpcb)->pcb_gs = 0;
  486 #if 0                           
  487                                 PROC_LOCK(p);
  488                                 psignal(p, SIGBUS);
  489                                 PROC_UNLOCK(p);
  490 #endif                          
  491                                 goto out;
  492                         }
  493 
  494                         if (td->td_intr_nesting_level != 0)
  495                                 break;
  496 
  497                         /*
  498                          * Invalid segment selectors and out of bounds
  499                          * %eip's and %esp's can be set up in user mode.
  500                          * This causes a fault in kernel mode when the
  501                          * kernel tries to return to user mode.  We want
  502                          * to get this fault so that we can fix the
  503                          * problem here and not have to check all the
  504                          * selectors and pointers when the user changes
  505                          * them.
  506                          */
  507                         if (frame.tf_eip == (int)doreti_iret) {
  508                                 frame.tf_eip = (int)doreti_iret_fault;
  509                                 goto out;
  510                         }
  511                         if (frame.tf_eip == (int)doreti_popl_ds) {
  512                                 frame.tf_eip = (int)doreti_popl_ds_fault;
  513                                 goto out;
  514                         }
  515                         if (frame.tf_eip == (int)doreti_popl_es) {
  516                                 frame.tf_eip = (int)doreti_popl_es_fault;
  517                                 goto out;
  518                         }
  519                         if (frame.tf_eip == (int)doreti_popl_fs) {
  520                                 frame.tf_eip = (int)doreti_popl_fs_fault;
  521                                 goto out;
  522                         }
  523                         if (PCPU_GET(curpcb)->pcb_onfault != NULL) {
  524                                 frame.tf_eip =
  525                                     (int)PCPU_GET(curpcb)->pcb_onfault;
  526                                 goto out;
  527                         }
  528                         break;
  529 
  530                 case T_TSSFLT:
  531                         /*
  532                          * PSL_NT can be set in user mode and isn't cleared
  533                          * automatically when the kernel is entered.  This
  534                          * causes a TSS fault when the kernel attempts to
  535                          * `iret' because the TSS link is uninitialized.  We
  536                          * want to get this fault so that we can fix the
  537                          * problem here and not every time the kernel is
  538                          * entered.
  539                          */
  540                         if (frame.tf_eflags & PSL_NT) {
  541                                 frame.tf_eflags &= ~PSL_NT;
  542                                 goto out;
  543                         }
  544                         break;
  545 
  546                 case T_TRCTRAP:  /* trace trap */
  547                         if (frame.tf_eip == (int)IDTVEC(lcall_syscall)) {
  548                                 /*
  549                                  * We've just entered system mode via the
  550                                  * syscall lcall.  Continue single stepping
  551                                  * silently until the syscall handler has
  552                                  * saved the flags.
  553                                  */
  554                                 goto out;
  555                         }
  556                         if (frame.tf_eip == (int)IDTVEC(lcall_syscall) + 1) {
  557                                 /*
  558                                  * The syscall handler has now saved the
  559                                  * flags.  Stop single stepping it.
  560                                  */
  561                                 frame.tf_eflags &= ~PSL_T;
  562                                 goto out;
  563                         }
  564                         /*
  565                          * Ignore debug register trace traps due to
  566                          * accesses in the user's address space, which
  567                          * can happen under several conditions such as
  568                          * if a user sets a watchpoint on a buffer and
  569                          * then passes that buffer to a system call.
  570                          * We still want to get TRCTRAPS for addresses
  571                          * in kernel space because that is useful when
  572                          * debugging the kernel.
  573                          */
  574                         /* XXX Giant */
  575                         if (user_dbreg_trap() && 
  576                            !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)) {
  577                                 /*
  578                                  * Reset breakpoint bits because the
  579                                  * processor doesn't
  580                                  */
  581                                 load_dr6(rdr6() & 0xfffffff0);
  582                                 goto out;
  583                         }
  584                         /*
  585                          * FALLTHROUGH (TRCTRAP kernel mode, kernel address)
  586                          */
  587                 case T_BPTFLT:
  588                         /*
  589                          * If KDB is enabled, let it handle the debugger trap.
  590                          * Otherwise, debugger traps "can't happen".
  591                          */
  592 #ifdef KDB
  593                         /* XXX Giant */
  594                         if (kdb_trap(type, 0, &frame))
  595                                 goto out;
  596 #endif
  597                         break;
  598 
  599 #ifdef DEV_ISA
  600                 case T_NMI:
  601 #ifdef POWERFAIL_NMI
  602                         mtx_lock(&Giant);
  603                         if (time_second - lastalert > 10) {
  604                                 log(LOG_WARNING, "NMI: power fail\n");
  605                                 sysbeep(TIMER_FREQ/880, hz);
  606                                 lastalert = time_second;
  607                         }
  608                         mtx_unlock(&Giant);
  609                         goto out;
  610 #else /* !POWERFAIL_NMI */
  611                         /* XXX Giant */
  612                         /* machine/parity/power fail/"kitchen sink" faults */
  613                         if (isa_nmi(code) == 0) {
  614 #ifdef KDB
  615                                 /*
  616                                  * NMI can be hooked up to a pushbutton
  617                                  * for debugging.
  618                                  */
  619                                 if (kdb_on_nmi) {
  620                                         printf ("NMI ... going to debugger\n");
  621                                         kdb_trap(type, 0, &frame);
  622                                 }
  623 #endif /* KDB */
  624                                 goto out;
  625                         } else if (panic_on_nmi == 0)
  626                                 goto out;
  627                         /* FALLTHROUGH */
  628 #endif /* POWERFAIL_NMI */
  629 #endif /* DEV_ISA */
  630                 }
  631 
  632                 trap_fatal(&frame, eva);
  633                 goto out;
  634         }
  635 
  636         /* Translate fault for emulators (e.g. Linux) */
  637         if (*p->p_sysent->sv_transtrap)
  638                 i = (*p->p_sysent->sv_transtrap)(i, type);
  639 
  640         trapsignal(td, i, ucode);
  641 
  642 #ifdef DEBUG
  643         if (type <= MAX_TRAP_MSG) {
  644                 uprintf("fatal process exception: %s",
  645                         trap_msg[type]);
  646                 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
  647                         uprintf(", fault VA = 0x%lx", (u_long)eva);
  648                 uprintf("\n");
  649         }
  650 #endif
  651 
  652 user:
  653         userret(td, &frame, sticks);
  654         mtx_assert(&Giant, MA_NOTOWNED);
  655 userout:
  656 out:
  657         return;
  658 }
  659 
  660 static int
  661 trap_pfault(frame, usermode, eva)
  662         struct trapframe *frame;
  663         int usermode;
  664         vm_offset_t eva;
  665 {
  666         vm_offset_t va;
  667         struct vmspace *vm = NULL;
  668         vm_map_t map = 0;
  669         int rv = 0;
  670         vm_prot_t ftype;
  671         struct thread *td = curthread;
  672         struct proc *p = td->td_proc;
  673 
  674         va = trunc_page(eva);
  675         if (va >= KERNBASE) {
  676                 /*
  677                  * Don't allow user-mode faults in kernel address space.
  678                  * An exception:  if the faulting address is the invalid
  679                  * instruction entry in the IDT, then the Intel Pentium
  680                  * F00F bug workaround was triggered, and we need to
  681                  * treat it is as an illegal instruction, and not a page
  682                  * fault.
  683                  */
  684 #if defined(I586_CPU) && !defined(NO_F00F_HACK)
  685                 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug)
  686                         return -2;
  687 #endif
  688                 if (usermode)
  689                         goto nogo;
  690 
  691                 map = kernel_map;
  692         } else {
  693                 /*
  694                  * This is a fault on non-kernel virtual memory.
  695                  * vm is initialized above to NULL. If curproc is NULL
  696                  * or curproc->p_vmspace is NULL the fault is fatal.
  697                  */
  698                 if (p != NULL)
  699                         vm = p->p_vmspace;
  700 
  701                 if (vm == NULL)
  702                         goto nogo;
  703 
  704                 map = &vm->vm_map;
  705         }
  706 
  707         if (frame->tf_err & PGEX_W)
  708                 ftype = VM_PROT_WRITE;
  709         else
  710                 ftype = VM_PROT_READ;
  711 
  712         if (map != kernel_map) {
  713                 /*
  714                  * Keep swapout from messing with us during this
  715                  *      critical time.
  716                  */
  717                 PROC_LOCK(p);
  718                 ++p->p_lock;
  719                 PROC_UNLOCK(p);
  720 
  721                 /* Fault in the user page: */
  722                 rv = vm_fault(map, va, ftype,
  723                               (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY
  724                                                       : VM_FAULT_NORMAL);
  725 
  726                 PROC_LOCK(p);
  727                 --p->p_lock;
  728                 PROC_UNLOCK(p);
  729         } else {
  730                 /*
  731                  * Don't have to worry about process locking or stacks in the
  732                  * kernel.
  733                  */
  734                 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
  735         }
  736         if (rv == KERN_SUCCESS)
  737                 return (0);
  738 nogo:
  739         if (!usermode) {
  740                 if (td->td_intr_nesting_level == 0 &&
  741                     PCPU_GET(curpcb)->pcb_onfault != NULL) {
  742                         frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault;
  743                         return (0);
  744                 }
  745                 trap_fatal(frame, eva);
  746                 return (-1);
  747         }
  748 
  749         /* kludge to pass faulting virtual address to sendsig */
  750         frame->tf_err = eva;
  751 
  752         return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
  753 }
  754 
  755 static void
  756 trap_fatal(frame, eva)
  757         struct trapframe *frame;
  758         vm_offset_t eva;
  759 {
  760         int code, type, ss, esp;
  761         struct soft_segment_descriptor softseg;
  762         char *msg;
  763 
  764         code = frame->tf_err;
  765         type = frame->tf_trapno;
  766         sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg);
  767 
  768         if (type <= MAX_TRAP_MSG)
  769                 msg = trap_msg[type];
  770         else
  771                 msg = "UNKNOWN";
  772         printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg,
  773             frame->tf_eflags & PSL_VM ? "vm86" :
  774             ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel");
  775 #ifdef SMP
  776         /* two separate prints in case of a trap on an unmapped page */
  777         printf("cpuid = %d; ", PCPU_GET(cpuid));
  778         printf("apic id = %02x\n", PCPU_GET(apic_id));
  779 #endif
  780         if (type == T_PAGEFLT) {
  781                 printf("fault virtual address   = 0x%x\n", eva);
  782                 printf("fault code              = %s %s, %s\n",
  783                         code & PGEX_U ? "user" : "supervisor",
  784                         code & PGEX_W ? "write" : "read",
  785                         code & PGEX_P ? "protection violation" : "page not present");
  786         }
  787         printf("instruction pointer     = 0x%x:0x%x\n",
  788                frame->tf_cs & 0xffff, frame->tf_eip);
  789         if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) {
  790                 ss = frame->tf_ss & 0xffff;
  791                 esp = frame->tf_esp;
  792         } else {
  793                 ss = GSEL(GDATA_SEL, SEL_KPL);
  794                 esp = (int)&frame->tf_esp;
  795         }
  796         printf("stack pointer           = 0x%x:0x%x\n", ss, esp);
  797         printf("frame pointer           = 0x%x:0x%x\n", ss, frame->tf_ebp);
  798         printf("code segment            = base 0x%x, limit 0x%x, type 0x%x\n",
  799                softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type);
  800         printf("                        = DPL %d, pres %d, def32 %d, gran %d\n",
  801                softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32,
  802                softseg.ssd_gran);
  803         printf("processor eflags        = ");
  804         if (frame->tf_eflags & PSL_T)
  805                 printf("trace trap, ");
  806         if (frame->tf_eflags & PSL_I)
  807                 printf("interrupt enabled, ");
  808         if (frame->tf_eflags & PSL_NT)
  809                 printf("nested task, ");
  810         if (frame->tf_eflags & PSL_RF)
  811                 printf("resume, ");
  812         if (frame->tf_eflags & PSL_VM)
  813                 printf("vm86, ");
  814         printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12);
  815         printf("current process         = ");
  816         if (curproc) {
  817                 printf("%lu (%s)\n",
  818                     (u_long)curproc->p_pid, curproc->p_comm ?
  819                     curproc->p_comm : "");
  820         } else {
  821                 printf("Idle\n");
  822         }
  823 
  824 #ifdef KDB
  825         if (debugger_on_panic || kdb_active) {
  826                 register_t eflags;
  827                 eflags = intr_disable();
  828                 if (kdb_trap(type, 0, frame)) {
  829                         intr_restore(eflags);
  830                         return;
  831                 }
  832                 intr_restore(eflags);
  833         }
  834 #endif
  835         printf("trap number             = %d\n", type);
  836         if (type <= MAX_TRAP_MSG)
  837                 panic("%s", trap_msg[type]);
  838         else
  839                 panic("unknown/reserved trap");
  840 }
  841 
  842 /*
  843  * Double fault handler. Called when a fault occurs while writing
  844  * a frame for a trap/exception onto the stack. This usually occurs
  845  * when the stack overflows (such is the case with infinite recursion,
  846  * for example).
  847  *
  848  * XXX Note that the current PTD gets replaced by IdlePTD when the
  849  * task switch occurs. This means that the stack that was active at
  850  * the time of the double fault is not available at <kstack> unless
  851  * the machine was idle when the double fault occurred. The downside
  852  * of this is that "trace <ebp>" in ddb won't work.
  853  */
  854 void
  855 dblfault_handler()
  856 {
  857         printf("\nFatal double fault:\n");
  858         printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip));
  859         printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp));
  860         printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp));
  861 #ifdef SMP
  862         /* two separate prints in case of a trap on an unmapped page */
  863         printf("cpuid = %d; ", PCPU_GET(cpuid));
  864         printf("apic id = %02x\n", PCPU_GET(apic_id));
  865 #endif
  866         panic("double fault");
  867 }
  868 
  869 /*
  870  *      syscall -       system call request C handler
  871  *
  872  *      A system call is essentially treated as a trap.
  873  */
  874 void
  875 syscall(frame)
  876         struct trapframe frame;
  877 {
  878         caddr_t params;
  879         struct sysent *callp;
  880         struct thread *td = curthread;
  881         struct proc *p = td->td_proc;
  882         register_t orig_tf_eflags;
  883         u_int sticks;
  884         int error;
  885         int narg;
  886         int args[8];
  887         u_int code;
  888 
  889         /*
  890          * note: PCPU_LAZY_INC() can only be used if we can afford
  891          * occassional inaccuracy in the count.
  892          */
  893         PCPU_LAZY_INC(cnt.v_syscall);
  894 
  895 #ifdef DIAGNOSTIC
  896         if (ISPL(frame.tf_cs) != SEL_UPL) {
  897                 mtx_lock(&Giant);       /* try to stabilize the system XXX */
  898                 panic("syscall");
  899                 /* NOT REACHED */
  900                 mtx_unlock(&Giant);
  901         }
  902 #endif
  903 
  904         sticks = td->td_sticks;
  905         td->td_frame = &frame;
  906         if (td->td_ucred != p->p_ucred) 
  907                 cred_update_thread(td);
  908         if (p->p_flag & P_SA)
  909                 thread_user_enter(td);
  910         params = (caddr_t)frame.tf_esp + sizeof(int);
  911         code = frame.tf_eax;
  912         orig_tf_eflags = frame.tf_eflags;
  913 
  914         if (p->p_sysent->sv_prepsyscall) {
  915                 /*
  916                  * The prep code is MP aware.
  917                  */
  918                 (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, &params);
  919         } else {
  920                 /*
  921                  * Need to check if this is a 32 bit or 64 bit syscall.
  922                  * fuword is MP aware.
  923                  */
  924                 if (code == SYS_syscall) {
  925                         /*
  926                          * Code is first argument, followed by actual args.
  927                          */
  928                         code = fuword(params);
  929                         params += sizeof(int);
  930                 } else if (code == SYS___syscall) {
  931                         /*
  932                          * Like syscall, but code is a quad, so as to maintain
  933                          * quad alignment for the rest of the arguments.
  934                          */
  935                         code = fuword(params);
  936                         params += sizeof(quad_t);
  937                 }
  938         }
  939 
  940         if (p->p_sysent->sv_mask)
  941                 code &= p->p_sysent->sv_mask;
  942 
  943         if (code >= p->p_sysent->sv_size)
  944                 callp = &p->p_sysent->sv_table[0];
  945         else
  946                 callp = &p->p_sysent->sv_table[code];
  947 
  948         narg = callp->sy_narg & SYF_ARGMASK;
  949 
  950         /*
  951          * copyin and the ktrsyscall()/ktrsysret() code is MP-aware
  952          */
  953         if (params != NULL && narg != 0)
  954                 error = copyin(params, (caddr_t)args,
  955                     (u_int)(narg * sizeof(int)));
  956         else
  957                 error = 0;
  958                 
  959 #ifdef KTRACE
  960         if (KTRPOINT(td, KTR_SYSCALL))
  961                 ktrsyscall(code, narg, args);
  962 #endif
  963 
  964         CTR4(KTR_SYSC, "syscall enter thread %p pid %d proc %s code %d", td,
  965             td->td_proc->p_pid, td->td_proc->p_comm, code);
  966 
  967         /*
  968          * Try to run the syscall without Giant if the syscall
  969          * is MP safe.
  970          */
  971         if ((callp->sy_narg & SYF_MPSAFE) == 0)
  972                 mtx_lock(&Giant);
  973 
  974         if (error == 0) {
  975                 td->td_retval[0] = 0;
  976                 td->td_retval[1] = frame.tf_edx;
  977 
  978                 STOPEVENT(p, S_SCE, narg);
  979 
  980                 PTRACESTOP_SC(p, td, S_PT_SCE);
  981 
  982                 AUDIT_SYSCALL_ENTER(code, td);
  983                 error = (*callp->sy_call)(td, args);
  984                 AUDIT_SYSCALL_EXIT(error, td);
  985         }
  986 
  987         switch (error) {
  988         case 0:
  989                 frame.tf_eax = td->td_retval[0];
  990                 frame.tf_edx = td->td_retval[1];
  991                 frame.tf_eflags &= ~PSL_C;
  992                 break;
  993 
  994         case ERESTART:
  995                 /*
  996                  * Reconstruct pc, assuming lcall $X,y is 7 bytes,
  997                  * int 0x80 is 2 bytes. We saved this in tf_err.
  998                  */
  999                 frame.tf_eip -= frame.tf_err;
 1000                 break;
 1001 
 1002         case EJUSTRETURN:
 1003                 break;
 1004 
 1005         default:
 1006                 if (p->p_sysent->sv_errsize) {
 1007                         if (error >= p->p_sysent->sv_errsize)
 1008                                 error = -1;     /* XXX */
 1009                         else
 1010                                 error = p->p_sysent->sv_errtbl[error];
 1011                 }
 1012                 frame.tf_eax = error;
 1013                 frame.tf_eflags |= PSL_C;
 1014                 break;
 1015         }
 1016 
 1017         /*
 1018          * Release Giant if we previously set it.
 1019          */
 1020         if ((callp->sy_narg & SYF_MPSAFE) == 0)
 1021                 mtx_unlock(&Giant);
 1022 
 1023         /*
 1024          * Traced syscall.
 1025          */
 1026         if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) {
 1027                 frame.tf_eflags &= ~PSL_T;
 1028                 trapsignal(td, SIGTRAP, 0);
 1029         }
 1030 
 1031         /*
 1032          * Handle reschedule and other end-of-syscall issues
 1033          */
 1034         userret(td, &frame, sticks);
 1035 
 1036         CTR4(KTR_SYSC, "syscall exit thread %p pid %d proc %s code %d", td,
 1037             td->td_proc->p_pid, td->td_proc->p_comm, code);
 1038 
 1039 #ifdef KTRACE
 1040         if (KTRPOINT(td, KTR_SYSRET))
 1041                 ktrsysret(code, error, td->td_retval[0]);
 1042 #endif
 1043 
 1044         /*
 1045          * This works because errno is findable through the
 1046          * register set.  If we ever support an emulation where this
 1047          * is not the case, this code will need to be revisited.
 1048          */
 1049         STOPEVENT(p, S_SCX, code);
 1050 
 1051         PTRACESTOP_SC(p, td, S_PT_SCX);
 1052 
 1053         WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning",
 1054             (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???");
 1055         mtx_assert(&sched_lock, MA_NOTOWNED);
 1056         mtx_assert(&Giant, MA_NOTOWNED);
 1057 }
 1058 

Cache object: 6b35003d47515e2142c29231dc602605


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