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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. #include <debug.h>
  36.  
  37. void exception(void)
  38. {
  39.     int excno;
  40.     __u32 epc;
  41.     __u32 epc_shift = 0;
  42.     pri_t pri;
  43.  
  44.     ASSERT(CPU != NULL);
  45.  
  46.     /*
  47.      * NOTE ON OPERATION ORDERING
  48.      *
  49.      * On entry, cpu_priority_high() must be called before exception bit is cleared.
  50.      * On exit, exception bit must be set before cpu_priority_restore() is called.
  51.      */
  52.  
  53.     pri = cpu_priority_high();
  54.     epc = cp0_epc_read();
  55.     cp0_status_write(cp0_status_read() & ~ cp0_status_exl_exception_bit);
  56.  
  57.     if (THREAD) {
  58.         THREAD->saved_pri = pri;
  59.         THREAD->saved_epc = epc;
  60.     }
  61.     /* decode exception number and process the exception */
  62.     switch (excno = (cp0_cause_read() >> 2) & 0x1f) {
  63.         case EXC_Int:
  64.             interrupt();
  65.             break;
  66.         case EXC_TLBL:
  67.         case EXC_TLBS:
  68.             tlb_invalid();
  69.             break;
  70.         case EXC_Mod:
  71.             panic("unhandled TLB Modification Exception\n");
  72.             break;
  73.         case EXC_AdEL:
  74.             panic("unhandled Address Error Exception - load or instruction fetch\n");
  75.             break;
  76.         case EXC_AdES:
  77.             panic("unhandled Address Error Exception - store\n");
  78.             break;
  79.         case EXC_IBE:
  80.             panic("unhandled Bus Error Exception - fetch instruction\n");
  81.             break;
  82.         case EXC_DBE:
  83.             panic("unhandled Bus Error Exception - data reference: load or store\n");
  84.             break;
  85.         case EXC_Bp:
  86.             /* it is necessary to not re-execute BREAK instruction after returning from Exception handler
  87.                (see page 138 in R4000 Manual for more information) */
  88.             epc_shift = 4;
  89.             break;
  90.         case EXC_RI:
  91.             panic("unhandled Reserved Instruction Exception\n");
  92.             break;
  93.         case EXC_CpU:
  94.             panic("unhandled Coprocessor Unusable Exception\n");
  95.             break;
  96.         case EXC_Ov:
  97.             panic("unhandled Arithmetic Overflow Exception\n");
  98.             break;
  99.         case EXC_Tr:
  100.             panic("unhandled Trap Exception\n");
  101.             break;
  102.         case EXC_VCEI:
  103.             panic("unhandled Virtual Coherency Exception - instruction\n");
  104.             break;
  105.         case EXC_FPE:
  106.             panic("unhandled Floating-Point Exception\n");
  107.             break;
  108.         case EXC_WATCH:
  109.             panic("unhandled reference to WatchHi/WatchLo address\n");
  110.             break;
  111.         case EXC_VCED:
  112.             panic("unhandled Virtual Coherency Exception - data\n");
  113.             break;
  114.         default:
  115.             panic("unhandled exception %d\n", excno);
  116.     }
  117.    
  118.     if (THREAD) {
  119.         pri = THREAD->saved_pri;
  120.         epc = THREAD->saved_epc;
  121.     }
  122.  
  123.     cp0_epc_write(epc + epc_shift);
  124.     cp0_status_write(cp0_status_read() | cp0_status_exl_exception_bit);
  125.     cpu_priority_restore(pri);
  126. }
  127.