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Diffstat (limited to 'libgloss/mips/entry.S')
| -rw-r--r-- | libgloss/mips/entry.S | 281 |
1 files changed, 0 insertions, 281 deletions
diff --git a/libgloss/mips/entry.S b/libgloss/mips/entry.S deleted file mode 100644 index 3630c552f..000000000 --- a/libgloss/mips/entry.S +++ /dev/null @@ -1,281 +0,0 @@ -/* entry.S - exception handler for emulating MIPS16 'entry' and 'exit' - pseudo-instructions. These instructions are generated by the compiler - when the -mentry switch is used. The instructions are not implemented - in the MIPS16 CPU; hence the exception handler that emulates them. - - This module contains the following public functions: - - * void __install_entry_handler(void); - - This function installs the entry/exit exception handler. It should - be called before executing any MIPS16 functions that were compiled with - -mentry, typically before main() is called. - - * void __remove_entry_handler(void); - - This function removes the entry/exit exception handler. It should - be called when the program is exiting, or when it is known that no - more MIPS16 functions compiled with -mentry will be called. -*/ - -#ifdef __mips16 -/* This file contains 32 bit assembly code. */ - .set nomips16 -#endif - -#include "regs.S" - -#define CAUSE_EXCMASK 0x3c /* mask for ExcCode in Cause Register */ -#define EXC_RI 0x28 /* 101000 == 10 << 2 */ - -/* Set DEBUG to 1 to enable recording of the last 16 interrupt causes. */ - -#define DEBUG 0 - -#if DEBUG - - .sdata -int_count: - .space 4 /* interrupt count modulo 16 */ -int_cause: - .space 4*16 /* last 16 interrupt causes */ -#endif - - .text - - .set noreorder /* Do NOT reorder instructions */ - - -/* __entry_exit_handler - the reserved instruction exception handler - that emulates the entry and exit instruction. */ - -__entry_exit_handler: - .set noat /* Do NOT use at register */ -#if DEBUG -/* Must avoid using 'la' pseudo-op because it uses gp register, which - may not have a good value in an exception handler. */ - -# la k0, int_count /* intcount = (intcount + 1) & 0xf */ - lui k0 ,%hi(int_count) - addiu k0, k0 ,%lo(int_count) - lw k1, (k0) - addiu k1, k1, 1 - andi k1, k1, 0x0f - sw k1, (k0) -# la k0, int_cause /* k1 = &int_cause[intcount] */ - lui k0, %hi(int_cause) - addiu k0, k0, %lo(int_cause) - sll k1, k1, 2 - add k1, k1, k0 -#endif - mfc0 k0, C0_CAUSE /* Fetch cause */ -#if DEBUG - sw k0, -4(k1) /* Save exception cause in buffer */ -#endif - mfc0 k1, C0_EPC /* Check for Reserved Inst. without */ - and k0, CAUSE_EXCMASK /* destroying any register */ - subu k0, EXC_RI - bne k0, zero, check_others /* Sorry, go do something else */ - - and k0, k1, 1 /* Check for TR mode (pc.0 = 1) */ - beq k0, zero, ri_in_32 /* Sorry, RI in 32-bit mode */ - xor k1, 1 - -/* Since we now are going to emulate or die, we can use all the T-registers */ -/* that MIPS16 does not use (at, t0-t8), and we don't have to save them. */ - - .set at /* Now it's ok to use at again */ - -#if 0 - j leave - rfe -#endif - - lhu t0, 0(k1) /* Fetch the offending instruction */ - xor t8, k1, 1 /* Prepare t8 for exit */ - and t1, t0, 0xf81f /* Check for entry/exit opcode */ - bne t1, 0xe809, other_ri - -deareg: and t1, t0, 0x0700 /* Isolate the three a-bits */ - srl t1, 6 /* Adjust them so x4 is applied */ - slt t2, t1, 17 /* See if this is the exit instruction */ - beqz t2, doexit - la t2, savea - subu t2, t1 - jr t2 /* Jump into the instruction table */ - rfe /* We run the rest in user-mode */ - - /* This is the entry instruction! */ - sw a3, 12(sp) /* 4: a0-a3 saved */ - sw a2, 8(sp) /* 3: a0-a2 saved */ - sw a1, 4(sp) /* 2: a0-a1 saved */ - sw a0, 0(sp) /* 1: a0 saved */ -savea: /* 0: No arg regs saved */ - -dera: and t1, t0, 0x0020 /* Isolate the save-ra bit */ - move t7, sp /* Temporary SP */ - beq t1, zero, desreg - subu sp, 32 /* Default SP adjustment */ - sw ra, -4(t7) - subu t7, 4 - -desreg: and t1, t0, 0x00c0 /* Isolate the two s-bits */ - beq t1, zero, leave - subu t1, 0x0040 - beq t1, zero, leave /* Only one to save... */ - sw s0, -4(t7) /* Do the first one */ - sw s1, -8(t7) /* Do the last one */ - -leave: jr t8 /* Exit to unmodified EPC */ - nop /* Urgh - the only nop!! */ - -doexf0: mtc1 v0,$f0 /* Copy float value */ - b doex2 - -doexf1: mtc1 v1,$f0 /* Copy double value */ - mtc1 v0,$f1 - b doex2 - -doexit: slt t2, t1, 21 - beq t2, zero, doexf0 - slt t2, t1, 25 - beq t2, zero, doexf1 - -doex2: and t1, t0, 0x0020 /* Isolate ra bit */ - beq t1, zero, dxsreg /* t1 holds ra-bit */ - addu t7, sp, 32 /* Temporary SP */ - lw ra, -4(t7) - subu t7, 4 - -dxsreg: and t1, t0, 0x00c0 /* Isolate the two s-bits */ - beq t1, zero, leavex - subu t1, 0x0040 - beq t1, zero, leavex /* Only one to save... */ - lw s0, -4(t7) /* Do the first one */ - lw s1, -8(t7) /* Do the last one */ - -leavex: jr ra /* Exit to ra */ - addu sp, 32 /* Clean up stack pointer */ - -/* Come here for exceptions we can't handle. */ - -ri_in_32: -other_ri: -check_others: /* call the previous handler */ - la k0,__previous - jr k0 - nop - -__exception_code: - .set noreorder - la k0, __entry_exit_handler -# lui k0, %hi(exception) -# addiu k0, k0, %lo(exception) - jr k0 - nop - .set reorder -__exception_code_end: - - .data -__previous: - .space (__exception_code_end - __exception_code) - .text - - -/* void __install_entry_handler(void) - - Install our entry/exit reserved instruction exception handler. -*/ - .ent __install_entry_handler - .globl __install_entry_handler -__install_entry_handler: - .set noreorder - mfc0 a0,C0_SR - nop - li a1,SR_BEV - and a1,a1,a0 - beq a1,$0,baseaddr - lui a0,0x8000 /* delay slot */ - lui a0,0xbfc0 - addiu a0,a0,0x0100 -baseaddr: - addiu a0,a0,0x080 /* a0 = base vector table address */ - li a1,(__exception_code_end - __exception_code) - la a2,__exception_code - la a3,__previous -/* there must be a better way of doing this???? */ -copyloop: - lw v0,0(a0) - sw v0,0(a3) - lw v0,0(a2) - sw v0,0(a0) - addiu a0,a0,4 - addiu a2,a2,4 - addiu a3,a3,4 - subu a1,a1,4 - bne a1,$0,copyloop - nop - j ra - nop - .set reorder - .end __install_entry_handler - - -/* void __remove_entry_handler(void); - - Remove our entry/exit reserved instruction exception handler. -*/ - - .ent __remove_entry_handler - .globl __remove_entry_handler -__remove_entry_handler: - .set noreorder - - mfc0 a0,C0_SR - nop - li a1,SR_BEV - and a1,a1,a0 - beq a1,$0,res_baseaddr - lui a0,0x8000 /* delay slot */ - lui a0,0xbfc0 - addiu a0,a0,0x0200 -res_baseaddr: - addiu a0,a0,0x0180 /* a0 = base vector table address */ - li a1,(__exception_code_end - __exception_code) - la a3,__previous - -/* there must be a better way of doing this???? */ -res_copyloop: - lw v0,0(a3) - sw v0,0(a0) - addiu a0,a0,4 - addiu a3,a3,4 - subu a1,a1,4 - bne a1,$0,res_copyloop - nop - j ra - nop - .set reorder - .end __remove_entry_handler - - -/* software_init_hook - install entry/exit handler and arrange to have it - removed at exit. This function is called by crt0.S. */ - - .text - .globl software_init_hook - .ent software_init_hook -software_init_hook: - .set noreorder - subu sp, sp, 8 /* allocate stack space */ - sw ra, 4(sp) /* save return address */ - jal __install_entry_handler /* install entry/exit handler */ - nop - lui a0, %hi(__remove_entry_handler) /* arrange for exit to */ - jal atexit /* de-install handler */ - addiu a0, a0, %lo(__remove_entry_handler) /* delay slot */ - lw ra, 4(sp) /* get return address */ - j ra /* return */ - addu sp, sp, 8 /* deallocate stack */ - .set reorder - .end software_init_hook |