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  1. /*
  2.  * Copyright (C) 2003-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <arch/exception.h>
  30. #include <arch/interrupt.h>
  31. #include <panic.h>
  32. #include <arch/cp0.h>
  33. #include <arch/types.h>
  34. #include <arch.h>
  35. #include <debug.h>
  36. #include <proc/thread.h>
  37.  
  38. void exception(struct exception_regdump *pstate)
  39. {
  40.     int cause;
  41.     int excno;
  42.     __u32 epc_shift = 0;
  43.  
  44.     ASSERT(CPU != NULL);
  45.  
  46.     /*
  47.      * NOTE ON OPERATION ORDERING
  48.      *
  49.      * On entry, interrupts_disable() must be called before
  50.      * exception bit is cleared.
  51.      */
  52.  
  53.     interrupts_disable();
  54.     cp0_status_write(cp0_status_read() & ~ (cp0_status_exl_exception_bit |
  55.                         cp0_status_um_bit));
  56.  
  57.     /* Save pstate so that the threads can access it */
  58.     /* If THREAD->pstate is set, this is nested exception,
  59.      * do not rewrite it
  60.      */
  61.     if (THREAD && !THREAD->pstate)
  62.         THREAD->pstate = pstate;
  63.  
  64.     cause = cp0_cause_read();
  65.     excno = cp0_cause_excno(cause);
  66.     /* decode exception number and process the exception */
  67.     switch (excno) {
  68.         case EXC_Int:
  69.             interrupt(pstate);
  70.             break;
  71.         case EXC_TLBL:
  72.         case EXC_TLBS:
  73.             tlb_invalid(pstate);
  74.             break;
  75.         case EXC_CpU:
  76. #ifdef FPU_LAZY    
  77.             if (cp0_cause_coperr(cause) == fpu_cop_id)
  78.                 scheduler_fpu_lazy_request();
  79.             else
  80. #endif
  81.                 panic("unhandled Coprocessor Unusable Exception\n");
  82.             break;
  83.         case EXC_Mod:
  84.             tlb_modified(pstate);
  85.             break;
  86.         case EXC_AdEL:
  87.             panic("unhandled Address Error Exception - load or instruction fetch\n");
  88.             break;
  89.         case EXC_AdES:
  90.             panic("unhandled Address Error Exception - store\n");
  91.             break;
  92.         case EXC_IBE:
  93.             panic("unhandled Bus Error Exception - fetch instruction\n");
  94.             break;
  95.         case EXC_DBE:
  96.             panic("unhandled Bus Error Exception - data reference: load or store\n");
  97.             break;
  98.         case EXC_Bp:
  99.             /* it is necessary to not re-execute BREAK instruction after returning from Exception handler
  100.                (see page 138 in R4000 Manual for more information) */
  101.             epc_shift = 4;
  102.             break;
  103.         case EXC_RI:
  104.             panic("unhandled Reserved Instruction Exception\n");
  105.             break;
  106.         case EXC_Ov:
  107.             panic("unhandled Arithmetic Overflow Exception\n");
  108.             break;
  109.         case EXC_Tr:
  110.             panic("unhandled Trap Exception\n");
  111.             break;
  112.         case EXC_VCEI:
  113.             panic("unhandled Virtual Coherency Exception - instruction\n");
  114.             break;
  115.         case EXC_FPE:
  116.             panic("unhandled Floating-Point Exception\n");
  117.             break;
  118.         case EXC_WATCH:
  119.             panic("unhandled reference to WatchHi/WatchLo address\n");
  120.             break;
  121.         case EXC_VCED:
  122.             panic("unhandled Virtual Coherency Exception - data\n");
  123.             break;
  124.         default:
  125.             panic("unhandled exception %d\n", excno);
  126.     }
  127.    
  128.     pstate->epc += epc_shift;
  129.     /* Set to NULL, so that we can still support nested
  130.      * exceptions
  131.      * TODO: We should probably set EXL bit before this command,
  132.      * nesting. On the other hand, if some exception occurs between
  133.      * here and ERET, it won't set anything on the pstate anyway.
  134.      */
  135.     if (THREAD)
  136.         THREAD->pstate = NULL;
  137. }
  138.