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  1. /*
  2.  * Copyright (C) 2001-2004 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.  
  36. void exception(void)
  37. {
  38.     int excno;
  39.     __u32 epc;
  40.     __u32 epc_shift = 0;
  41.     pri_t pri;
  42.    
  43.     pri = cpu_priority_high();
  44.     epc = cp0_epc_read();
  45.     cp0_status_write(cp0_status_read() & ~ cp0_status_exl_exception_bit);
  46.  
  47.     if (THREAD) {
  48.         THREAD->saved_pri = pri;
  49.         THREAD->saved_epc = epc;
  50.     }
  51.     /* decode exception number and process the exception */
  52.     switch (excno = (cp0_cause_read() >> 2) & 0x1f) {
  53.         case EXC_Int:
  54.             interrupt();
  55.             break;
  56.         case EXC_TLBL:
  57.         case EXC_TLBS:
  58.             tlb_invalid();
  59.             break;
  60.         case EXC_Mod:
  61.             panic("unhandled TLB Modification Exception\n");
  62.             break;
  63.         case EXC_AdEL:
  64.             panic("unhandled Address Error Exception - load or instruction fetch\n");
  65.             break;
  66.         case EXC_AdES:
  67.             panic("unhandled Address Error Exception - store\n");
  68.             break;
  69.         case EXC_IBE:
  70.             panic("unhandled Bus Error Exception - fetch instruction\n");
  71.             break;
  72.         case EXC_DBE:
  73.             panic("unhandled Bus Error Exception - data reference: load or store\n");
  74.             break;
  75.         case EXC_Bp:
  76.             /* it is necessary to not re-execute BREAK instruction after returning from Exception handler
  77.                (see page 138 in R4000 Manual for more information) */
  78.             epc_shift = 4;
  79.             break;
  80.         case EXC_RI:
  81.             panic("unhandled Reserved Instruction Exception\n");
  82.             break;
  83.         case EXC_CpU:
  84.             panic("unhandled Coprocessor Unusable Exception\n");
  85.             break;
  86.         case EXC_Ov:
  87.             panic("unhandled Arithmetic Overflow Exception\n");
  88.             break;
  89.         case EXC_Tr:
  90.             panic("unhandled Trap Exception\n");
  91.             break;
  92.         case EXC_VCEI:
  93.             panic("unhandled Virtual Coherency Exception - instruction\n");
  94.             break;
  95.         case EXC_FPE:
  96.             panic("unhandled Floating-Point Exception\n");
  97.             break;
  98.         case EXC_WATCH:
  99.             panic("unhandled reference to WatchHi/WatchLo address\n");
  100.             break;
  101.         case EXC_VCED:
  102.             panic("unhandled Virtual Coherency Exception - data\n");
  103.             break;
  104.         default:
  105.             panic("unhandled exception %d\n", excno);
  106.     }
  107.    
  108.     if (THREAD) {
  109.         pri = THREAD->saved_pri;
  110.         epc = THREAD->saved_epc;
  111.     }
  112.  
  113.     cp0_epc_write(epc + epc_shift);
  114.     cp0_status_write(cp0_status_read() | cp0_status_exl_exception_bit);
  115.     cpu_priority_restore(pri);
  116. }
  117.