arch/mips/kernel/head.S

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994, 1995 Waldorf Electronics
   7  * Written by Ralf Baechle and Andreas Busse
   8  * Copyright (C) 1994 - 99, 2003, 06 Ralf Baechle
   9  * Copyright (C) 1996 Paul M. Antoine
  10  * Modified for DECStation and hence R3000 support by Paul M. Antoine
  11  * Further modifications by David S. Miller and Harald Koerfgen
  12  * Copyright (C) 1999 Silicon Graphics, Inc.
  13  * Kevin Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
  14  * Copyright (C) 2000 MIPS Technologies, Inc.  All rights reserved.
  15  */
  16 #include <linux/init.h>
  17 #include <linux/threads.h>
  18
  19 #include <asm/addrspace.h>
  20 #include <asm/asm.h>
  21 #include <asm/asmmacro.h>
  22 #include <asm/irqflags.h>
  23 #include <asm/regdef.h>
  24 #include <asm/pgtable-bits.h>
  25 #include <asm/mipsregs.h>
  26 #include <asm/stackframe.h>
  27
  28 #include <kernel-entry-init.h>
  29
  30         /*
  31          * For the moment disable interrupts, mark the kernel mode and
  32          * set ST0_KX so that the CPU does not spit fire when using
  33          * 64-bit addresses.  A full initialization of the CPU's status
  34          * register is done later in per_cpu_trap_init().
  35          */
  36         .macro  setup_c0_status set clr
  37         .set    push
  38         mfc0    t0, CP0_STATUS
  39         or      t0, ST0_CU0|\set|0x1f|\clr
  40         xor     t0, 0x1f|\clr
  41         mtc0    t0, CP0_STATUS
  42         .set    noreorder
  43         sll     zero,3                          # ehb
  44         .set    pop
  45         .endm
  46
  47         .macro  setup_c0_status_pri
  48 #ifdef CONFIG_64BIT
  49         setup_c0_status ST0_KX 0
  50 #else
  51         setup_c0_status 0 0
  52 #endif
  53         .endm
  54
  55         .macro  setup_c0_status_sec
  56 #ifdef CONFIG_64BIT
  57         setup_c0_status ST0_KX ST0_BEV
  58 #else
  59         setup_c0_status 0 ST0_BEV
  60 #endif
  61         .endm
  62
  63 #ifndef CONFIG_NO_EXCEPT_FILL
  64         /*
  65          * Reserved space for exception handlers.
  66          * Necessary for machines which link their kernels at KSEG0.
  67          */
  68         .fill   0x400
  69 #endif
  70
  71 EXPORT(_stext)
  72
  73 #ifdef CONFIG_BOOT_RAW
  74         /*
  75          * Give us a fighting chance of running if execution beings at the
  76          * kernel load address.  This is needed because this platform does
  77          * not have a ELF loader yet.
  78          */
  79 FEXPORT(__kernel_entry)
  80         j       kernel_entry
  81 #endif
  82
  83         __REF
  84
  85 NESTED(kernel_entry, 16, sp)                    # kernel entry point
  86
  87         kernel_entry_setup                      # cpu specific setup
  88
  89         setup_c0_status_pri
  90
  91         /* We might not get launched at the address the kernel is linked to,
  92            so we jump there.  */
  93         PTR_LA  t0, 0f
  94         jr      t0
  95 0:
  96
  97         PTR_LA          t0, __bss_start         # clear .bss
  98         LONG_S          zero, (t0)
  99         PTR_LA          t1, __bss_stop - LONGSIZE
 100 1:
 101         PTR_ADDIU       t0, LONGSIZE
 102         LONG_S          zero, (t0)
 103         bne             t0, t1, 1b
 104
 105         LONG_S          a0, fw_arg0             # firmware arguments
 106         LONG_S          a1, fw_arg1
 107         LONG_S          a2, fw_arg2
 108         LONG_S          a3, fw_arg3
 109
 110         MTC0            zero, CP0_CONTEXT       # clear context register
 111         PTR_LA          $28, init_thread_union
 112         /* Set the SP after an empty pt_regs.  */
 113         PTR_LI          sp, _THREAD_SIZE - 32 - PT_SIZE
 114         PTR_ADDU        sp, $28
 115         back_to_back_c0_hazard
 116         set_saved_sp    sp, t0, t1
 117         PTR_SUBU        sp, 4 * SZREG           # init stack pointer
 118
 119         j               start_kernel
 120         END(kernel_entry)
 121
 122 #ifdef CONFIG_SMP
 123 /*
 124  * SMP slave cpus entry point.  Board specific code for bootstrap calls this
 125  * function after setting up the stack and gp registers.
 126  */
 127 NESTED(smp_bootstrap, 16, sp)
 128         smp_slave_setup
 129         setup_c0_status_sec
 130         j       start_secondary
 131         END(smp_bootstrap)
 132 #endif /* CONFIG_SMP */