The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/arm/arm/trap.c

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    1 /*      $NetBSD: fault.c,v 1.45 2003/11/20 14:44:36 scw Exp $   */
    2 
    3 /*-
    4  * Copyright 2004 Olivier Houchard
    5  * Copyright 2003 Wasabi Systems, Inc.
    6  * All rights reserved.
    7  *
    8  * Written by Steve C. Woodford for Wasabi Systems, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed for the NetBSD Project by
   21  *      Wasabi Systems, Inc.
   22  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
   23  *    or promote products derived from this software without specific prior
   24  *    written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
   30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   36  * POSSIBILITY OF SUCH DAMAGE.
   37  */
   38 /*-
   39  * Copyright (c) 1994-1997 Mark Brinicombe.
   40  * Copyright (c) 1994 Brini.
   41  * All rights reserved.
   42  *
   43  * This code is derived from software written for Brini by Mark Brinicombe
   44  *
   45  * Redistribution and use in source and binary forms, with or without
   46  * modification, are permitted provided that the following conditions
   47  * are met:
   48  * 1. Redistributions of source code must retain the above copyright
   49  *    notice, this list of conditions and the following disclaimer.
   50  * 2. Redistributions in binary form must reproduce the above copyright
   51  *    notice, this list of conditions and the following disclaimer in the
   52  *    documentation and/or other materials provided with the distribution.
   53  * 3. All advertising materials mentioning features or use of this software
   54  *    must display the following acknowledgement:
   55  *      This product includes software developed by Brini.
   56  * 4. The name of the company nor the name of the author may be used to
   57  *    endorse or promote products derived from this software without specific
   58  *    prior written permission.
   59  *
   60  * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
   61  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   62  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   63  * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
   64  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   65  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   66  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   67  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   68  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   69  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   70  * SUCH DAMAGE.
   71  *
   72  * RiscBSD kernel project
   73  *
   74  * fault.c
   75  *
   76  * Fault handlers
   77  *
   78  * Created      : 28/11/94
   79  */
   80 
   81 
   82 #include "opt_ktrace.h"
   83 
   84 #include <sys/cdefs.h>
   85 __FBSDID("$FreeBSD: releng/8.1/sys/arm/arm/trap.c 200443 2009-12-12 20:06:25Z kib $");
   86 
   87 #include <sys/param.h>
   88 #include <sys/systm.h>
   89 #include <sys/proc.h>
   90 #include <sys/kernel.h>
   91 #include <sys/lock.h>
   92 #include <sys/mutex.h>
   93 #include <sys/syscall.h>
   94 #include <sys/sysent.h>
   95 #include <sys/signalvar.h>
   96 #include <sys/ktr.h>
   97 #ifdef KTRACE
   98 #include <sys/uio.h>
   99 #include <sys/ktrace.h>
  100 #endif
  101 #include <sys/ptrace.h>
  102 #include <sys/pioctl.h>
  103 
  104 #include <vm/vm.h>
  105 #include <vm/pmap.h>
  106 #include <vm/vm_kern.h>
  107 #include <vm/vm_map.h>
  108 #include <vm/vm_extern.h>
  109 
  110 #include <machine/cpuconf.h>
  111 #include <machine/vmparam.h>
  112 #include <machine/frame.h>
  113 #include <machine/cpu.h>
  114 #include <machine/intr.h>
  115 #include <machine/pcb.h>
  116 #include <machine/proc.h>
  117 #include <machine/swi.h>
  118 
  119 #include <security/audit/audit.h>
  120 
  121 #ifdef KDB
  122 #include <sys/kdb.h>
  123 #endif
  124 
  125 
  126 void swi_handler(trapframe_t *);
  127 void undefinedinstruction(trapframe_t *);
  128 
  129 #include <machine/disassem.h>
  130 #include <machine/machdep.h>
  131  
  132 extern char fusubailout[];
  133 extern char *syscallnames[];
  134 
  135 #ifdef DEBUG
  136 int last_fault_code;    /* For the benefit of pmap_fault_fixup() */
  137 #endif
  138 
  139 #if defined(CPU_ARM7TDMI)
  140 /* These CPUs may need data/prefetch abort fixups */
  141 #define CPU_ABORT_FIXUP_REQUIRED
  142 #endif
  143 
  144 struct ksig {
  145         int signb;
  146         u_long code;
  147 };
  148 struct data_abort {
  149         int (*func)(trapframe_t *, u_int, u_int, struct thread *, struct ksig *);
  150         const char *desc;
  151 };
  152 
  153 static int dab_fatal(trapframe_t *, u_int, u_int, struct thread *, struct ksig *);
  154 static int dab_align(trapframe_t *, u_int, u_int, struct thread *, struct ksig *);
  155 static int dab_buserr(trapframe_t *, u_int, u_int, struct thread *, struct ksig *);
  156 
  157 static const struct data_abort data_aborts[] = {
  158         {dab_fatal,     "Vector Exception"},
  159         {dab_align,     "Alignment Fault 1"},
  160         {dab_fatal,     "Terminal Exception"},
  161         {dab_align,     "Alignment Fault 3"},
  162         {dab_buserr,    "External Linefetch Abort (S)"},
  163         {NULL,          "Translation Fault (S)"},
  164         {dab_buserr,    "External Linefetch Abort (P)"},
  165         {NULL,          "Translation Fault (P)"},
  166         {dab_buserr,    "External Non-Linefetch Abort (S)"},
  167         {NULL,          "Domain Fault (S)"},
  168         {dab_buserr,    "External Non-Linefetch Abort (P)"},
  169         {NULL,          "Domain Fault (P)"},
  170         {dab_buserr,    "External Translation Abort (L1)"},
  171         {NULL,          "Permission Fault (S)"},
  172         {dab_buserr,    "External Translation Abort (L2)"},
  173         {NULL,          "Permission Fault (P)"}
  174 };
  175 
  176 /* Determine if a fault came from user mode */
  177 #define TRAP_USERMODE(tf)       ((tf->tf_spsr & PSR_MODE) == PSR_USR32_MODE)
  178 
  179 /* Determine if 'x' is a permission fault */
  180 #define IS_PERMISSION_FAULT(x)                                  \
  181         (((1 << ((x) & FAULT_TYPE_MASK)) &                      \
  182           ((1 << FAULT_PERM_P) | (1 << FAULT_PERM_S))) != 0)
  183 
  184 static __inline void
  185 call_trapsignal(struct thread *td, int sig, u_long code)
  186 {
  187         ksiginfo_t ksi;
  188 
  189         ksiginfo_init_trap(&ksi);
  190         ksi.ksi_signo = sig;
  191         ksi.ksi_code = (int)code;
  192         trapsignal(td, &ksi);
  193 }
  194 
  195 static __inline int
  196 data_abort_fixup(trapframe_t *tf, u_int fsr, u_int far, struct thread *td, struct ksig *ksig)
  197 {
  198 #ifdef CPU_ABORT_FIXUP_REQUIRED
  199         int error;
  200 
  201         /* Call the cpu specific data abort fixup routine */
  202         error = cpu_dataabt_fixup(tf);
  203         if (__predict_true(error != ABORT_FIXUP_FAILED))
  204                 return (error);
  205 
  206         /*
  207          * Oops, couldn't fix up the instruction
  208          */
  209         printf("data_abort_fixup: fixup for %s mode data abort failed.\n",
  210             TRAP_USERMODE(tf) ? "user" : "kernel");
  211         printf("pc = 0x%08x, opcode 0x%08x, insn = ", tf->tf_pc,
  212             *((u_int *)tf->tf_pc));
  213         disassemble(tf->tf_pc);
  214 
  215         /* Die now if this happened in kernel mode */
  216         if (!TRAP_USERMODE(tf))
  217                 dab_fatal(tf, fsr, far, td, NULL, ksig);
  218 
  219         return (error);
  220 #else
  221         return (ABORT_FIXUP_OK);
  222 #endif /* CPU_ABORT_FIXUP_REQUIRED */
  223 }
  224 
  225 void
  226 data_abort_handler(trapframe_t *tf)
  227 {
  228         struct vm_map *map;
  229         struct pcb *pcb;
  230         struct thread *td;
  231         u_int user, far, fsr;
  232         vm_prot_t ftype;
  233         void *onfault;
  234         vm_offset_t va;
  235         int error = 0;
  236         struct ksig ksig;
  237         struct proc *p;
  238         
  239 
  240         /* Grab FAR/FSR before enabling interrupts */
  241         far = cpu_faultaddress();
  242         fsr = cpu_faultstatus();
  243 #if 0
  244         printf("data abort: %p (from %p %p)\n", (void*)far, (void*)tf->tf_pc,
  245             (void*)tf->tf_svc_lr);
  246 #endif
  247 
  248         /* Update vmmeter statistics */
  249 #if 0
  250         vmexp.traps++;
  251 #endif
  252 
  253         td = curthread;
  254         p = td->td_proc;
  255 
  256         PCPU_INC(cnt.v_trap);
  257         /* Data abort came from user mode? */
  258         user = TRAP_USERMODE(tf);
  259 
  260         if (user) {
  261                 td->td_pticks = 0;
  262                 td->td_frame = tf;              
  263                 if (td->td_ucred != td->td_proc->p_ucred)
  264                         cred_update_thread(td);
  265                 
  266         }
  267         /* Grab the current pcb */
  268         pcb = td->td_pcb;
  269         /* Re-enable interrupts if they were enabled previously */
  270         if (td->td_md.md_spinlock_count == 0) {
  271                 if (__predict_true(tf->tf_spsr & I32_bit) == 0)
  272                         enable_interrupts(I32_bit);
  273                 if (__predict_true(tf->tf_spsr & F32_bit) == 0)
  274                         enable_interrupts(F32_bit);
  275         }
  276                 
  277 
  278         /* Invoke the appropriate handler, if necessary */
  279         if (__predict_false(data_aborts[fsr & FAULT_TYPE_MASK].func != NULL)) {
  280                 if ((data_aborts[fsr & FAULT_TYPE_MASK].func)(tf, fsr, far,
  281                     td, &ksig)) {
  282                         goto do_trapsignal;
  283                 }
  284                 goto out;
  285         }
  286 
  287         /*
  288          * At this point, we're dealing with one of the following data aborts:
  289          *
  290          *  FAULT_TRANS_S  - Translation -- Section
  291          *  FAULT_TRANS_P  - Translation -- Page
  292          *  FAULT_DOMAIN_S - Domain -- Section
  293          *  FAULT_DOMAIN_P - Domain -- Page
  294          *  FAULT_PERM_S   - Permission -- Section
  295          *  FAULT_PERM_P   - Permission -- Page
  296          *
  297          * These are the main virtual memory-related faults signalled by
  298          * the MMU.
  299          */
  300 
  301         /* fusubailout is used by [fs]uswintr to avoid page faulting */
  302         if (__predict_false(pcb->pcb_onfault == fusubailout)) {
  303                 tf->tf_r0 = EFAULT;
  304                 tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
  305                 return;
  306         }
  307 
  308         /*
  309          * Make sure the Program Counter is sane. We could fall foul of
  310          * someone executing Thumb code, in which case the PC might not
  311          * be word-aligned. This would cause a kernel alignment fault
  312          * further down if we have to decode the current instruction.
  313          * XXX: It would be nice to be able to support Thumb at some point.
  314          */
  315         if (__predict_false((tf->tf_pc & 3) != 0)) {
  316                 if (user) {
  317                         /*
  318                          * Give the user an illegal instruction signal.
  319                          */
  320                         /* Deliver a SIGILL to the process */
  321                         ksig.signb = SIGILL;
  322                         ksig.code = 0;
  323                         goto do_trapsignal;
  324                 }
  325 
  326                 /*
  327                  * The kernel never executes Thumb code.
  328                  */
  329                 printf("\ndata_abort_fault: Misaligned Kernel-mode "
  330                     "Program Counter\n");
  331                 dab_fatal(tf, fsr, far, td, &ksig);
  332         }
  333 
  334         /* See if the cpu state needs to be fixed up */
  335         switch (data_abort_fixup(tf, fsr, far, td, &ksig)) {
  336         case ABORT_FIXUP_RETURN:
  337                 return;
  338         case ABORT_FIXUP_FAILED:
  339                 /* Deliver a SIGILL to the process */
  340                 ksig.signb = SIGILL;
  341                 ksig.code = 0;
  342                 goto do_trapsignal;
  343         default:
  344                 break;
  345         }
  346 
  347         va = trunc_page((vm_offset_t)far);
  348 
  349         /*
  350          * It is only a kernel address space fault iff:
  351          *      1. user == 0  and
  352          *      2. pcb_onfault not set or
  353          *      3. pcb_onfault set and not LDRT/LDRBT/STRT/STRBT instruction.
  354          */
  355         if (user == 0 && (va >= VM_MIN_KERNEL_ADDRESS ||
  356             (va < VM_MIN_ADDRESS && vector_page == ARM_VECTORS_LOW)) &&
  357             __predict_true((pcb->pcb_onfault == NULL ||
  358              (ReadWord(tf->tf_pc) & 0x05200000) != 0x04200000))) {
  359                 map = kernel_map;
  360 
  361                 /* Was the fault due to the FPE/IPKDB ? */
  362                 if (__predict_false((tf->tf_spsr & PSR_MODE)==PSR_UND32_MODE)) {
  363 
  364                         /*
  365                          * Force exit via userret()
  366                          * This is necessary as the FPE is an extension to
  367                          * userland that actually runs in a priveledged mode
  368                          * but uses USR mode permissions for its accesses.
  369                          */
  370                         user = 1;
  371                         ksig.signb = SIGSEGV;
  372                         ksig.code = 0;
  373                         goto do_trapsignal;
  374                 }
  375         } else {
  376                 map = &td->td_proc->p_vmspace->vm_map;
  377         }
  378 
  379         /*
  380          * We need to know whether the page should be mapped
  381          * as R or R/W. The MMU does not give us the info as
  382          * to whether the fault was caused by a read or a write.
  383          *
  384          * However, we know that a permission fault can only be
  385          * the result of a write to a read-only location, so
  386          * we can deal with those quickly.
  387          *
  388          * Otherwise we need to disassemble the instruction
  389          * responsible to determine if it was a write.
  390          */
  391         if (IS_PERMISSION_FAULT(fsr)) {
  392                 ftype = VM_PROT_WRITE; 
  393         } else {
  394                 u_int insn = ReadWord(tf->tf_pc);
  395 
  396                 if (((insn & 0x0c100000) == 0x04000000) ||      /* STR/STRB */
  397                     ((insn & 0x0e1000b0) == 0x000000b0) ||      /* STRH/STRD */
  398                     ((insn & 0x0a100000) == 0x08000000))        /* STM/CDT */
  399                 {
  400                         ftype = VM_PROT_WRITE; 
  401         }
  402                 else
  403                 if ((insn & 0x0fb00ff0) == 0x01000090)          /* SWP */
  404                         ftype = VM_PROT_READ | VM_PROT_WRITE; 
  405                 else
  406                         ftype = VM_PROT_READ; 
  407         }
  408 
  409         /*
  410          * See if the fault is as a result of ref/mod emulation,
  411          * or domain mismatch.
  412          */
  413 #ifdef DEBUG
  414         last_fault_code = fsr;
  415 #endif
  416         if (pmap_fault_fixup(vmspace_pmap(td->td_proc->p_vmspace), va, ftype,
  417             user)) {
  418                 goto out;
  419         }
  420 
  421         onfault = pcb->pcb_onfault;
  422         pcb->pcb_onfault = NULL;
  423         if (map != kernel_map) {
  424                 PROC_LOCK(p);
  425                 p->p_lock++;
  426                 PROC_UNLOCK(p);
  427         }
  428         error = vm_fault(map, va, ftype, (ftype & VM_PROT_WRITE) ? 
  429             VM_FAULT_DIRTY : VM_FAULT_NORMAL);
  430         pcb->pcb_onfault = onfault;
  431 
  432         if (map != kernel_map) {
  433                 PROC_LOCK(p);
  434                 p->p_lock--;
  435                 PROC_UNLOCK(p);
  436         }
  437         if (__predict_true(error == 0))
  438                 goto out;
  439         if (user == 0) {
  440                 if (pcb->pcb_onfault) {
  441                         tf->tf_r0 = error;
  442                         tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
  443                         return;
  444                 }
  445 
  446                 printf("\nvm_fault(%p, %x, %x, 0) -> %x\n", map, va, ftype,
  447                     error);
  448                 dab_fatal(tf, fsr, far, td, &ksig);
  449         }
  450 
  451 
  452         if (error == ENOMEM) {
  453                 printf("VM: pid %d (%s), uid %d killed: "
  454                     "out of swap\n", td->td_proc->p_pid, td->td_name,
  455                     (td->td_proc->p_ucred) ?
  456                      td->td_proc->p_ucred->cr_uid : -1);
  457                 ksig.signb = SIGKILL;
  458         } else {
  459                 ksig.signb = SIGSEGV;
  460         }
  461         ksig.code = 0;
  462 do_trapsignal:
  463         call_trapsignal(td, ksig.signb, ksig.code);
  464 out:
  465         /* If returning to user mode, make sure to invoke userret() */
  466         if (user)
  467                 userret(td, tf);
  468 }
  469 
  470 /*
  471  * dab_fatal() handles the following data aborts:
  472  *
  473  *  FAULT_WRTBUF_0 - Vector Exception
  474  *  FAULT_WRTBUF_1 - Terminal Exception
  475  *
  476  * We should never see these on a properly functioning system.
  477  *
  478  * This function is also called by the other handlers if they
  479  * detect a fatal problem.
  480  *
  481  * Note: If 'l' is NULL, we assume we're dealing with a prefetch abort.
  482  */
  483 static int
  484 dab_fatal(trapframe_t *tf, u_int fsr, u_int far, struct thread *td, struct ksig *ksig)
  485 {
  486         const char *mode;
  487 
  488         mode = TRAP_USERMODE(tf) ? "user" : "kernel";
  489 
  490         disable_interrupts(I32_bit|F32_bit);
  491         if (td != NULL) {
  492                 printf("Fatal %s mode data abort: '%s'\n", mode,
  493                     data_aborts[fsr & FAULT_TYPE_MASK].desc);
  494                 printf("trapframe: %p\nFSR=%08x, FAR=", tf, fsr);
  495                 if ((fsr & FAULT_IMPRECISE) == 0)
  496                         printf("%08x, ", far);
  497                 else
  498                         printf("Invalid,  ");
  499                 printf("spsr=%08x\n", tf->tf_spsr);
  500         } else {
  501                 printf("Fatal %s mode prefetch abort at 0x%08x\n",
  502                     mode, tf->tf_pc);
  503                 printf("trapframe: %p, spsr=%08x\n", tf, tf->tf_spsr);
  504         }
  505 
  506         printf("r0 =%08x, r1 =%08x, r2 =%08x, r3 =%08x\n",
  507             tf->tf_r0, tf->tf_r1, tf->tf_r2, tf->tf_r3);
  508         printf("r4 =%08x, r5 =%08x, r6 =%08x, r7 =%08x\n",
  509             tf->tf_r4, tf->tf_r5, tf->tf_r6, tf->tf_r7);
  510         printf("r8 =%08x, r9 =%08x, r10=%08x, r11=%08x\n",
  511             tf->tf_r8, tf->tf_r9, tf->tf_r10, tf->tf_r11);
  512         printf("r12=%08x, ", tf->tf_r12);
  513 
  514         if (TRAP_USERMODE(tf))
  515                 printf("usp=%08x, ulr=%08x",
  516                     tf->tf_usr_sp, tf->tf_usr_lr);
  517         else
  518                 printf("ssp=%08x, slr=%08x",
  519                     tf->tf_svc_sp, tf->tf_svc_lr);
  520         printf(", pc =%08x\n\n", tf->tf_pc);
  521 
  522 #ifdef KDB
  523         if (debugger_on_panic || kdb_active)
  524                 kdb_trap(fsr, 0, tf);
  525 #endif
  526         panic("Fatal abort");
  527         /*NOTREACHED*/
  528 }
  529 
  530 /*
  531  * dab_align() handles the following data aborts:
  532  *
  533  *  FAULT_ALIGN_0 - Alignment fault
  534  *  FAULT_ALIGN_1 - Alignment fault
  535  *
  536  * These faults are fatal if they happen in kernel mode. Otherwise, we
  537  * deliver a bus error to the process.
  538  */
  539 static int
  540 dab_align(trapframe_t *tf, u_int fsr, u_int far, struct thread *td, struct ksig *ksig)
  541 {
  542 
  543         /* Alignment faults are always fatal if they occur in kernel mode */
  544         if (!TRAP_USERMODE(tf)) {
  545                 if (!td || !td->td_pcb->pcb_onfault)
  546                         dab_fatal(tf, fsr, far, td, ksig);
  547                 tf->tf_r0 = EFAULT;
  548                 tf->tf_pc = (int)td->td_pcb->pcb_onfault;
  549                 return (0);
  550         }
  551 
  552         /* pcb_onfault *must* be NULL at this point */
  553 
  554         /* See if the cpu state needs to be fixed up */
  555         (void) data_abort_fixup(tf, fsr, far, td, ksig);
  556 
  557         /* Deliver a bus error signal to the process */
  558         ksig->code = 0;
  559         ksig->signb = SIGBUS;
  560         td->td_frame = tf;
  561 
  562         return (1);
  563 }
  564 
  565 /*
  566  * dab_buserr() handles the following data aborts:
  567  *
  568  *  FAULT_BUSERR_0 - External Abort on Linefetch -- Section
  569  *  FAULT_BUSERR_1 - External Abort on Linefetch -- Page
  570  *  FAULT_BUSERR_2 - External Abort on Non-linefetch -- Section
  571  *  FAULT_BUSERR_3 - External Abort on Non-linefetch -- Page
  572  *  FAULT_BUSTRNL1 - External abort on Translation -- Level 1
  573  *  FAULT_BUSTRNL2 - External abort on Translation -- Level 2
  574  *
  575  * If pcb_onfault is set, flag the fault and return to the handler.
  576  * If the fault occurred in user mode, give the process a SIGBUS.
  577  *
  578  * Note: On XScale, FAULT_BUSERR_0, FAULT_BUSERR_1, and FAULT_BUSERR_2
  579  * can be flagged as imprecise in the FSR. This causes a real headache
  580  * since some of the machine state is lost. In this case, tf->tf_pc
  581  * may not actually point to the offending instruction. In fact, if
  582  * we've taken a double abort fault, it generally points somewhere near
  583  * the top of "data_abort_entry" in exception.S.
  584  *
  585  * In all other cases, these data aborts are considered fatal.
  586  */
  587 static int
  588 dab_buserr(trapframe_t *tf, u_int fsr, u_int far, struct thread *td, struct ksig *ksig)
  589 {
  590         struct pcb *pcb = td->td_pcb;
  591 
  592 #ifdef __XSCALE__
  593         if ((fsr & FAULT_IMPRECISE) != 0 &&
  594             (tf->tf_spsr & PSR_MODE) == PSR_ABT32_MODE) {
  595                 /*
  596                  * Oops, an imprecise, double abort fault. We've lost the
  597                  * r14_abt/spsr_abt values corresponding to the original
  598                  * abort, and the spsr saved in the trapframe indicates
  599                  * ABT mode.
  600                  */
  601                 tf->tf_spsr &= ~PSR_MODE;
  602 
  603                 /*
  604                  * We use a simple heuristic to determine if the double abort
  605                  * happened as a result of a kernel or user mode access.
  606                  * If the current trapframe is at the top of the kernel stack,
  607                  * the fault _must_ have come from user mode.
  608                  */
  609                 if (tf != ((trapframe_t *)pcb->un_32.pcb32_sp) - 1) {
  610                         /*
  611                          * Kernel mode. We're either about to die a
  612                          * spectacular death, or pcb_onfault will come
  613                          * to our rescue. Either way, the current value
  614                          * of tf->tf_pc is irrelevant.
  615                          */
  616                         tf->tf_spsr |= PSR_SVC32_MODE;
  617                         if (pcb->pcb_onfault == NULL)
  618                                 printf("\nKernel mode double abort!\n");
  619                 } else {
  620                         /*
  621                          * User mode. We've lost the program counter at the
  622                          * time of the fault (not that it was accurate anyway;
  623                          * it's not called an imprecise fault for nothing).
  624                          * About all we can do is copy r14_usr to tf_pc and
  625                          * hope for the best. The process is about to get a
  626                          * SIGBUS, so it's probably history anyway.
  627                          */
  628                         tf->tf_spsr |= PSR_USR32_MODE;
  629                         tf->tf_pc = tf->tf_usr_lr;
  630                 }
  631         }
  632 
  633         /* FAR is invalid for imprecise exceptions */
  634         if ((fsr & FAULT_IMPRECISE) != 0)
  635                 far = 0;
  636 #endif /* __XSCALE__ */
  637 
  638         if (pcb->pcb_onfault) {
  639                 tf->tf_r0 = EFAULT;
  640                 tf->tf_pc = (register_t)(intptr_t) pcb->pcb_onfault;
  641                 return (0);
  642         }
  643 
  644         /* See if the cpu state needs to be fixed up */
  645         (void) data_abort_fixup(tf, fsr, far, td, ksig);
  646 
  647         /*
  648          * At this point, if the fault happened in kernel mode, we're toast
  649          */
  650         if (!TRAP_USERMODE(tf))
  651                 dab_fatal(tf, fsr, far, td, ksig);
  652 
  653         /* Deliver a bus error signal to the process */
  654         ksig->signb = SIGBUS;
  655         ksig->code = 0;
  656         td->td_frame = tf;
  657 
  658         return (1);
  659 }
  660 
  661 static __inline int
  662 prefetch_abort_fixup(trapframe_t *tf, struct ksig *ksig)
  663 {
  664 #ifdef CPU_ABORT_FIXUP_REQUIRED
  665         int error;
  666 
  667         /* Call the cpu specific prefetch abort fixup routine */
  668         error = cpu_prefetchabt_fixup(tf);
  669         if (__predict_true(error != ABORT_FIXUP_FAILED))
  670                 return (error);
  671 
  672         /*
  673          * Oops, couldn't fix up the instruction
  674          */
  675         printf(
  676             "prefetch_abort_fixup: fixup for %s mode prefetch abort failed.\n",
  677             TRAP_USERMODE(tf) ? "user" : "kernel");
  678         printf("pc = 0x%08x, opcode 0x%08x, insn = ", tf->tf_pc,
  679             *((u_int *)tf->tf_pc));
  680         disassemble(tf->tf_pc);
  681 
  682         /* Die now if this happened in kernel mode */
  683         if (!TRAP_USERMODE(tf))
  684                 dab_fatal(tf, 0, tf->tf_pc, NULL, ksig);
  685 
  686         return (error);
  687 #else
  688         return (ABORT_FIXUP_OK);
  689 #endif /* CPU_ABORT_FIXUP_REQUIRED */
  690 }
  691 
  692 /*
  693  * void prefetch_abort_handler(trapframe_t *tf)
  694  *
  695  * Abort handler called when instruction execution occurs at
  696  * a non existent or restricted (access permissions) memory page.
  697  * If the address is invalid and we were in SVC mode then panic as
  698  * the kernel should never prefetch abort.
  699  * If the address is invalid and the page is mapped then the user process
  700  * does no have read permission so send it a signal.
  701  * Otherwise fault the page in and try again.
  702  */
  703 void
  704 prefetch_abort_handler(trapframe_t *tf)
  705 {
  706         struct thread *td;
  707         struct proc * p;
  708         struct vm_map *map;
  709         vm_offset_t fault_pc, va;
  710         int error = 0;
  711         struct ksig ksig;
  712 
  713 
  714 #if 0
  715         /* Update vmmeter statistics */
  716         uvmexp.traps++;
  717 #endif
  718 #if 0
  719         printf("prefetch abort handler: %p %p\n", (void*)tf->tf_pc,
  720             (void*)tf->tf_usr_lr);
  721 #endif
  722         
  723         td = curthread;
  724         p = td->td_proc;
  725         PCPU_INC(cnt.v_trap);
  726 
  727         if (TRAP_USERMODE(tf)) {
  728                 td->td_frame = tf;
  729                 if (td->td_ucred != td->td_proc->p_ucred)
  730                         cred_update_thread(td);
  731         }
  732         fault_pc = tf->tf_pc;
  733         if (td->td_md.md_spinlock_count == 0) {
  734                 if (__predict_true(tf->tf_spsr & I32_bit) == 0)
  735                         enable_interrupts(I32_bit);
  736                 if (__predict_true(tf->tf_spsr & F32_bit) == 0)
  737                         enable_interrupts(F32_bit);
  738         }
  739          
  740 
  741                        
  742         /* See if the cpu state needs to be fixed up */
  743         switch (prefetch_abort_fixup(tf, &ksig)) {
  744         case ABORT_FIXUP_RETURN:
  745                 return;
  746         case ABORT_FIXUP_FAILED:
  747                 /* Deliver a SIGILL to the process */
  748                 ksig.signb = SIGILL;
  749                 ksig.code = 0;
  750                 td->td_frame = tf;
  751                 goto do_trapsignal;
  752         default:
  753                 break;
  754         }
  755 
  756         /* Prefetch aborts cannot happen in kernel mode */
  757         if (__predict_false(!TRAP_USERMODE(tf)))
  758                 dab_fatal(tf, 0, tf->tf_pc, NULL, &ksig);
  759         td->td_pticks = 0;
  760 
  761 
  762         /* Ok validate the address, can only execute in USER space */
  763         if (__predict_false(fault_pc >= VM_MAXUSER_ADDRESS ||
  764             (fault_pc < VM_MIN_ADDRESS && vector_page == ARM_VECTORS_LOW))) {
  765                 ksig.signb = SIGSEGV;
  766                 ksig.code = 0;
  767                 goto do_trapsignal;
  768         }
  769 
  770         map = &td->td_proc->p_vmspace->vm_map;
  771         va = trunc_page(fault_pc);
  772 
  773         /*
  774          * See if the pmap can handle this fault on its own...
  775          */
  776 #ifdef DEBUG
  777         last_fault_code = -1;
  778 #endif
  779         if (pmap_fault_fixup(map->pmap, va, VM_PROT_READ, 1))
  780                 goto out;
  781 
  782         if (map != kernel_map) {
  783                 PROC_LOCK(p);
  784                 p->p_lock++;
  785                 PROC_UNLOCK(p);
  786         }
  787 
  788         error = vm_fault(map, va, VM_PROT_READ | VM_PROT_EXECUTE,
  789             VM_FAULT_NORMAL);
  790         if (map != kernel_map) {
  791                 PROC_LOCK(p);
  792                 p->p_lock--;
  793                 PROC_UNLOCK(p);
  794         }
  795 
  796         if (__predict_true(error == 0))
  797                 goto out;
  798 
  799         if (error == ENOMEM) {
  800                 printf("VM: pid %d (%s), uid %d killed: "
  801                     "out of swap\n", td->td_proc->p_pid, td->td_name,
  802                     (td->td_proc->p_ucred) ?
  803                      td->td_proc->p_ucred->cr_uid : -1);
  804                 ksig.signb = SIGKILL;
  805         } else {
  806                 ksig.signb = SIGSEGV;
  807         }
  808         ksig.code = 0;
  809 
  810 do_trapsignal:
  811         call_trapsignal(td, ksig.signb, ksig.code);
  812 
  813 out:
  814         userret(td, tf);
  815 
  816 }
  817 
  818 extern int badaddr_read_1(const uint8_t *, uint8_t *);
  819 extern int badaddr_read_2(const uint16_t *, uint16_t *);
  820 extern int badaddr_read_4(const uint32_t *, uint32_t *);
  821 /*
  822  * Tentatively read an 8, 16, or 32-bit value from 'addr'.
  823  * If the read succeeds, the value is written to 'rptr' and zero is returned.
  824  * Else, return EFAULT.
  825  */
  826 int
  827 badaddr_read(void *addr, size_t size, void *rptr)
  828 {
  829         union {
  830                 uint8_t v1;
  831                 uint16_t v2;
  832                 uint32_t v4;
  833         } u;
  834         int rv;
  835 
  836         cpu_drain_writebuf();
  837 
  838         /* Read from the test address. */
  839         switch (size) {
  840         case sizeof(uint8_t):
  841                 rv = badaddr_read_1(addr, &u.v1);
  842                 if (rv == 0 && rptr)
  843                         *(uint8_t *) rptr = u.v1;
  844                 break;
  845 
  846         case sizeof(uint16_t):
  847                 rv = badaddr_read_2(addr, &u.v2);
  848                 if (rv == 0 && rptr)
  849                         *(uint16_t *) rptr = u.v2;
  850                 break;
  851 
  852         case sizeof(uint32_t):
  853                 rv = badaddr_read_4(addr, &u.v4);
  854                 if (rv == 0 && rptr)
  855                         *(uint32_t *) rptr = u.v4;
  856                 break;
  857 
  858         default:
  859                 panic("badaddr: invalid size (%lu)", (u_long) size);
  860         }
  861 
  862         /* Return EFAULT if the address was invalid, else zero */
  863         return (rv);
  864 }
  865 
  866 #define MAXARGS 8
  867 static void
  868 syscall(struct thread *td, trapframe_t *frame, u_int32_t insn)
  869 {
  870         struct proc *p = td->td_proc;
  871         int code, error;
  872         u_int nap, nargs;
  873         register_t *ap, *args, copyargs[MAXARGS];
  874         struct sysent *callp;
  875 
  876         PCPU_INC(cnt.v_syscall);
  877         td->td_pticks = 0;
  878         if (td->td_ucred != td->td_proc->p_ucred)
  879                 cred_update_thread(td);
  880         switch (insn & SWI_OS_MASK) {
  881         case 0: /* XXX: we need our own one. */
  882                 nap = 4;
  883                 break;
  884         default:
  885                 call_trapsignal(td, SIGILL, 0);
  886                 userret(td, frame);
  887                 return;
  888         }
  889         code = insn & 0x000fffff;                
  890         td->td_pticks = 0;
  891         ap = &frame->tf_r0;
  892         if (code == SYS_syscall) {
  893                 code = *ap++;
  894                 
  895                 nap--;
  896         } else if (code == SYS___syscall) {
  897                 code = ap[_QUAD_LOWWORD];
  898                 nap -= 2;
  899                 ap += 2;
  900         }
  901         if (p->p_sysent->sv_mask)
  902                 code &= p->p_sysent->sv_mask;
  903         if (code >= p->p_sysent->sv_size)
  904                 callp = &p->p_sysent->sv_table[0];
  905         else
  906                 callp = &p->p_sysent->sv_table[code];
  907         nargs = callp->sy_narg;
  908         memcpy(copyargs, ap, nap * sizeof(register_t));
  909         if (nargs > nap) {
  910                 error = copyin((void *)frame->tf_usr_sp, copyargs + nap,
  911                     (nargs - nap) * sizeof(register_t));
  912                 if (error)
  913                         goto bad;
  914         }
  915         args = copyargs;
  916         error = 0;
  917 #ifdef KTRACE
  918         if (KTRPOINT(td, KTR_SYSCALL))
  919                 ktrsyscall(code, nargs, args);
  920 #endif
  921                 
  922         CTR4(KTR_SYSC, "syscall enter thread %p pid %d proc %s code %d", td,
  923             td->td_proc->p_pid, td->td_name, code);
  924         if (error == 0) {
  925                 td->td_retval[0] = 0;
  926                 td->td_retval[1] = 0;
  927                 STOPEVENT(p, S_SCE, callp->sy_narg);
  928                 PTRACESTOP_SC(p, td, S_PT_SCE);
  929                 AUDIT_SYSCALL_ENTER(code, td);
  930                 error = (*callp->sy_call)(td, args);
  931                 AUDIT_SYSCALL_EXIT(error, td);
  932                 KASSERT(td->td_ar == NULL, 
  933                     ("returning from syscall with td_ar set!"));
  934         }
  935 bad:
  936         cpu_set_syscall_retval(td, error);
  937 
  938         WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning",
  939             (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???");
  940         KASSERT(td->td_critnest == 0,
  941             ("System call %s returning in a critical section",
  942             (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"));
  943         KASSERT(td->td_locks == 0,
  944             ("System call %s returning with %d locks held",
  945             (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???",
  946             td->td_locks));
  947 
  948         userret(td, frame);
  949         CTR4(KTR_SYSC, "syscall exit thread %p pid %d proc %s code %d", td,
  950             td->td_proc->p_pid, td->td_name, code);
  951         
  952         STOPEVENT(p, S_SCX, code);
  953         PTRACESTOP_SC(p, td, S_PT_SCX);
  954 #ifdef KTRACE
  955         if (KTRPOINT(td, KTR_SYSRET))
  956                 ktrsysret(code, error, td->td_retval[0]);
  957 #endif
  958 }
  959 
  960 void
  961 swi_handler(trapframe_t *frame)
  962 {
  963         struct thread *td = curthread;
  964         uint32_t insn;
  965 
  966         td->td_frame = frame;
  967         
  968         td->td_pticks = 0;
  969         /*
  970          * Make sure the program counter is correctly aligned so we
  971          * don't take an alignment fault trying to read the opcode.
  972          */
  973         if (__predict_false(((frame->tf_pc - INSN_SIZE) & 3) != 0)) {
  974                 call_trapsignal(td, SIGILL, 0);
  975                 userret(td, frame);
  976                 return;
  977         }
  978         insn = *(u_int32_t *)(frame->tf_pc - INSN_SIZE);
  979         /*
  980          * Enable interrupts if they were enabled before the exception.
  981          * Since all syscalls *should* come from user mode it will always
  982          * be safe to enable them, but check anyway. 
  983          */       
  984         if (td->td_md.md_spinlock_count == 0) {
  985                 if (__predict_true(frame->tf_spsr & I32_bit) == 0)
  986                         enable_interrupts(I32_bit);
  987                 if (__predict_true(frame->tf_spsr & F32_bit) == 0)
  988                         enable_interrupts(F32_bit);
  989         }
  990          
  991         syscall(td, frame, insn);
  992 }
  993 

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