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Diffstat (limited to 'private/ntos/fw/mips/j3trap.s')
| -rw-r--r-- | private/ntos/fw/mips/j3trap.s | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/private/ntos/fw/mips/j3trap.s b/private/ntos/fw/mips/j3trap.s new file mode 100644 index 000000000..2e4f7fabe --- /dev/null +++ b/private/ntos/fw/mips/j3trap.s @@ -0,0 +1,288 @@ +#if defined(JAZZ) && defined(R3000) + +/*++ + +Copyright (c) 1990 Microsoft Corporation + +Module Name: + + j3trap.s + +Abstract: + + This module will handle exceptions + It will save the state of the processor, check jump table + to see if it should dispatch somewhere, and then return to + monitor. + +Author: + + John Cooper (johncoop) 4-Oct-90 + +Environment: + + Kernel mode + +Revision History: + + +--*/ +// +// include header file +// + +#include "ksmips.h" +#include "selfmap.h" +#include "led.h" +#define PROM_BASE (KSEG1_BASE | 0x1fc00000) +#define PROM_ENTRY(x) (PROM_BASE + ((x) * 8)) + +.set noat +.set noreorder +.text + + + + .globl ExceptionDispatch +ExceptionDispatch: +/*++ + +Routine Description: + + This routine will use a lookup table based on the exception + cause, to call an exception handler. If the value in + lookup table is zero, the state of the machine is saved, + and control is passed to monitor. + The return value of the exception handler indicates where + control should go when the exception condition is cleared. + +Arguments: + + K1 - Contains the cause register. + +Return Value: + + None. + +--*/ + // + // Need to save return address before calling an exec. handler. + // + + li k0,GLOBAL_DATA_BASE // base of saved state + sw ra, 0x7C(k0) // save ra + + // + // Get jump vector from lookup table based on cause. + // Call handler if value is non-zero + // + li k0,EXCEPTION_JUMP_TABLE // base of jump table + addu k0,k0,k1 // add offset to base + lw k1,0(k0) // get jump vector from tbl + li k0,GOTO_MONITOR // go back to monitor by default + beq k1,zero,ExceptionReturn // go save state and call mon. + li ra,COMMONEXCEPTION // load this value into ra. + // this will get passed as + // argument to MonitorInit() + // which will then print a message + // saying a COMMONEXCEPTION occured. + // COMMON EXCEPTION is an unaligned #. + // if k1 != zero the jal reloads ra + jal k1 // with the right value. + nop // control will pass to the + // Exception Return routine next. + // return value from handler + // should be returned in k0. + // this is passed as argument + // to ExceptionReturn. + + .globl ExceptionReturn +ExceptionReturn: + +/*++ + +Routine Description: + + This routine will restore any registers that have been modified + by the trap handler. Control is then passed back to one + of three places. Either the monitor, the location stored in the + EPC, or the value supplied in the argumnet k0. + +Arguments: + + k0 - supplies indication of where to go after clearing exception. + if bits [1:0] are 00B then go to location indicated + in k0. if bits [1:0] are GOTO_MONITOR, then control + is passed to MonitorReInit(). if bits are GOTO_EPC then + control is returned to location where exception occured. + +Return Value: + + None. + +--*/ + + + // + // Return value from exec. handler is in k0. + // if low bits are 00, then return to value in k0 + // if low bits are 01, then return to Err PC + // if low bits are 10, then return to monitor + // + andi k1,k0,3 // k1 = k0 & 3 + beq k1,zero,returntok0 // go if return code is 0 + andi k1,k0,GOTO_EPC // k1 = k0 & 1 + bne k1,zero,returntoEPC // if bit1=1 then GOTO_EPC + andi k1,k0,GOTO_MONITOR // k1 = k0 & 2 + bne k1,zero,returntomonitor // if bit2=1 then GOTO_MONITOR + nop + b returntomonitor // default return action + nop +returntok0: + + // + // restore value to ra + // + + li k1,GLOBAL_DATA_BASE // base of saved state + lw ra, 0x7C(k1) // restore ra + + // + // return to value in k0 when clearing exception condition + // do this by putting k0 in EPC + // + j k0 // return to k0 + rfe // restore pre-exc state +returntoEPC: + + // + // restore value to ra + // + + li k1,GLOBAL_DATA_BASE // base of saved state + + // + // return to location where exeception was caused + // + mfc0 k0,epc // get return PC from cop0 + lw ra, 0x7C(k1) // restore ra + j k0 // jump to (EPC) + rfe // clear exception condition + +returntomonitor: + + // + // return to monitor by calling MonitorReInit() + // + //li k0,MONITOR_LINK_ADDRESS + //j k0 + //rfe // restore pre-exc state + li k0,PROM_ENTRY(14) + lui a0,LED_BLINK + jal k0 + ori a0,a0,0xFC + + .globl TLBMiss +TLBMiss: + +/*++ + +Routine Description: + + This routine will modifiy the TLB when a miss occurs. + It will take the failed virtual address and place it + in the TLB as a physical address. This will make + a one to one mapping between virtual and physical. + If the address is E2000000 - E3FFFFFF, then routine + will subtract off 52000000 for eisa spaces. + This routine is only expected to be used for the R3000 + + Note that the control from the exception vector is passed + to the dispatch routine. The dispatch routine calls this + routine - control is passed back to the dispatch routine. + +Arguments: + + None. + +Return Value: + + None. + +--*/ + + // + // load bad virtual address - the address that missed in TLB + // + + mfc0 k0,badvaddr + + // + // mask out page offset to get virtual page number. + // offset differs in size between R4000 and R3000 + // + + li k1,0xFFFFF000 + + and k0,k0,k1 + + // + // store bad virtual address in the EntryHi register to + // + + mtc0 k0,entryhi + + // + // check if value is between E2000000 - E3FFFFFF + // set bits in range (01FFFFFF) and compare to E3FFFFFF + // + + li k1,0x01FFFFFF + or k0,k0,k1 + li k1,0xE3FFFFFF + + bne k1,k0,noteisa + + // + // subtract off 52000000 + // + + mfc0 k0,entryhi + li k1,0x52000000 + sub k0,k0,k1 + nop + +noteisa: + // + // set non-cached, dirty, valid, and global bits + // + // + + li k1,(1<<ENTRYLO_D) + (1<<ENTRYLO_V) + (1<<ENTRYLO_G) + (1<<ENTRYLO_N) + or k0,k0,k1 + mtc0 k0,entrylo + + // + // set index to 63 to write the 63 entry. always replace this + // entry to preserve all the other entries. + // + + li k0,(63<<INDEX_INDEX) + mtc0 k0,index + nop + + // + // write the tlb entry. + // + + tlbwi + nop + + // + // return from exception - tell dispatch to go to EPC + // + + j ra + li k0,GOTO_EPC + +#endif // R3000 && JAZZ |