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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [arch/] [mips/] [kernel/] [head.S] - Rev 1275
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994, 1995 Waldorf Electronics
* Written by Ralf Baechle and Andreas Busse
* Copyright (C) 1995 - 1999 Ralf Baechle
* Copyright (C) 1996 Paul M. Antoine
* Modified for DECStation and hence R3000 support by Paul M. Antoine
* Further modifications by David S. Miller and Harald Koerfgen
* Copyright (C) 1999 Silicon Graphics, Inc.
*
* Kevin Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/threads.h>
#include <asm/asm.h>
#include <asm/current.h>
#include <asm/offset.h>
#include <asm/pgtable-bits.h>
#include <asm/processor.h>
#include <asm/regdef.h>
#include <asm/cachectl.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>
.text
/*
* Reserved space for exception handlers.
* Necessary for machines which link their kernels at KSEG0.
*/
.fill 0x400
/* The following two symbols are used for kernel profiling. */
EXPORT(stext)
EXPORT(_stext)
__INIT
/* Cache Error */
LEAF(except_vec2_generic)
.set noreorder
.set noat
.set mips0
/*
* This is a very bad place to be. Our cache error
* detection has triggered. If we have write-back data
* in the cache, we may not be able to recover. As a
* first-order desperate measure, turn off KSEG0 cacheing.
*/
mfc0 k0,CP0_CONFIG
li k1,~CONF_CM_CMASK
and k0,k0,k1
ori k0,k0,CONF_CM_UNCACHED
mtc0 k0,CP0_CONFIG
/* Give it a few cycles to sink in... */
nop
nop
nop
j cache_parity_error
nop
END(except_vec2_generic)
.set at
/*
* Special interrupt vector for embedded MIPS. This is a
* dedicated interrupt vector which reduces interrupt processing
* overhead. The jump instruction will be inserted here at
* initialization time. This handler may only be 8 bytes in
* size!
*/
NESTED(except_vec4, 0, sp)
1: j 1b /* Dummy, will be replaced */
nop
END(except_vec4)
/*
* EJTAG debug exception handler.
* The EJTAG debug exception entry point is 0xbfc00480, which
* normally is in the boot PROM, so the boot PROM must do a
* unconditional jump to this vector.
*/
NESTED(except_vec_ejtag_debug, 0, sp)
j ejtag_debug_handler
nop
END(except_vec_ejtag_debug)
__FINIT
/*
* EJTAG debug exception handler.
*/
NESTED(ejtag_debug_handler, PT_SIZE, sp)
.set noat
.set noreorder
mtc0 k0, CP0_DESAVE
mfc0 k0, CP0_DEBUG
sll k0, k0, 30 # Check for SDBBP.
bgez k0, ejtag_return
la k0, ejtag_debug_buffer
sw k1, 0(k0)
SAVE_ALL
jal ejtag_exception_handler
move a0, sp
RESTORE_ALL
la k0, ejtag_debug_buffer
lw k1, 0(k0)
ejtag_return:
mfc0 k0, CP0_DESAVE
.set mips32
deret
.set mips0
nop
.set at
END(ejtag_debug_handler)
__INIT
/*
* NMI debug exception handler for MIPS reference boards.
* The NMI debug exception entry point is 0xbfc00000, which
* normally is in the boot PROM, so the boot PROM must do a
* unconditional jump to this vector.
*/
NESTED(except_vec_nmi, 0, sp)
j nmi_handler
nop
END(except_vec_nmi)
__FINIT
NESTED(nmi_handler, PT_SIZE, sp)
.set noat
.set noreorder
.set mips3
SAVE_ALL
jal nmi_exception_handler
move a0, sp
RESTORE_ALL
eret
.set at
.set mips0
END(nmi_handler)
__INIT
/*
* Kernel entry point
*/
NESTED(kernel_entry, 16, sp)
.set noreorder
/*
* The firmware/bootloader passes argc/argp/envp
* to us as arguments. But clear bss first because
* the romvec and other important info is stored there
* by prom_init().
*/
la t0, _edata
sw zero, (t0)
la t1, (_end - 4)
1:
addiu t0, 4
bne t0, t1, 1b
sw zero, (t0)
/*
* Stack for kernel and init, current variable
*/
la $28, init_task_union
addiu t0, $28, KERNEL_STACK_SIZE-32
subu sp, t0, 4*SZREG
sw t0, kernelsp
jal init_arch
nop
END(kernel_entry)
#ifdef CONFIG_SMP
/*
* SMP slave cpus entry point. Board specific code for bootstrap calls this
* function after setting up the stack and gp registers.
*/
LEAF(smp_bootstrap)
.set push
.set noreorder
mtc0 zero, CP0_WIRED
CLI
mfc0 t0, CP0_STATUS
li t1, ~(ST0_CU1|ST0_CU2|ST0_CU3|ST0_KX|ST0_SX|ST0_UX)
and t0, t1
or t0, (ST0_CU0);
jal start_secondary
mtc0 t0, CP0_STATUS
.set pop
END(smp_bootstrap)
#endif
__FINIT
/*
* This buffer is reserved for the use of the EJTAG debug
* handler.
*/
.data
EXPORT(ejtag_debug_buffer)
.fill 4
.comm kernelsp, NR_CPUS * 8, 8
.comm pgd_current, NR_CPUS * 8, 8
.macro page name, order=0
.globl \name
\name: .size \name, (_PAGE_SIZE << \order)
.org . + (_PAGE_SIZE << \order)
.type \name, @object
.endm
.data
.align 12
page swapper_pg_dir, _PGD_ORDER
page empty_bad_page, 0
page empty_bad_page_table, 0
page invalid_pte_table, 0
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