kernel/arch/unicore32/boot/compressed/head.S

   1 /*
   2  * linux/arch/unicore32/boot/compressed/head.S
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/linkage.h>
  13 #include <mach/memory.h>
  14
  15 #define csub    cmpsub
  16 #define cand    cmpand
  17 #define nop8    nop; nop; nop; nop; nop; nop; nop; nop
  18
  19                 .section ".start", #alloc, #execinstr
  20                 .text
  21 start:
  22                 .type   start,#function
  23
  24                 /* Initialize ASR, PRIV mode and INTR off */
  25                 mov     r0, #0xD3
  26                 mov.a   asr, r0
  27
  28                 adr     r0, LC0
  29                 ldm     (r1, r2, r3, r5, r6, r7, r8), [r0]+
  30                 ldw     sp, [r0+], #28
  31                 sub.a   r0, r0, r1              @ calculate the delta offset
  32
  33                 /*
  34                  * if delta is zero, we are running at the address
  35                  * we were linked at.
  36                  */
  37                 beq     not_relocated
  38
  39                 /*
  40                  * We're running at a different address.  We need to fix
  41                  * up various pointers:
  42                  *   r5 - zImage base address (_start)
  43                  *   r7 - GOT start
  44                  *   r8 - GOT end
  45                  */
  46                 add     r5, r5, r0
  47                 add     r7, r7, r0
  48                 add     r8, r8, r0
  49
  50                 /*
  51                  * we need to fix up pointers into the BSS region.
  52                  *   r2 - BSS start
  53                  *   r3 - BSS end
  54                  *   sp - stack pointer
  55                  */
  56                 add     r2, r2, r0
  57                 add     r3, r3, r0
  58                 add     sp, sp, r0
  59
  60                 /*
  61                  * Relocate all entries in the GOT table.
  62                  * This fixes up the C references.
  63                  *   r7 - GOT start
  64                  *   r8 - GOT end
  65                  */
  66 1001:           ldw     r1, [r7+], #0
  67                 add     r1, r1, r0
  68                 stw.w   r1, [r7]+, #4
  69                 csub.a  r7, r8
  70                 bub     1001b
  71
  72 not_relocated:
  73                 /*
  74                  * Clear BSS region.
  75                  *   r2 - BSS start
  76                  *   r3 - BSS end
  77                  */
  78                 mov     r0, #0
  79 1002:           stw.w   r0, [r2]+, #4
  80                 csub.a  r2, r3
  81                 bub     1002b
  82
  83                 /*
  84                  * Turn on the cache.
  85                  */
  86                 mov     r0, #0
  87                 movc    p0.c5, r0, #28          @ cache invalidate all
  88                 nop8
  89                 movc    p0.c6, r0, #6           @ tlb invalidate all
  90                 nop8
  91
  92                 mov     r0, #0x1c               @ en icache and wb dcache
  93                 movc    p0.c1, r0, #0
  94                 nop8
  95
  96                 /*
  97                  * Set up some pointers, for starting decompressing.
  98                  */
  99
 100                 mov     r1, sp                  @ malloc space above stack
 101                 add     r2, sp, #0x10000        @ 64k max
 102
 103                 /*
 104                  * Check to see if we will overwrite ourselves.
 105                  *   r4 = final kernel address
 106                  *   r5 = start of this image
 107                  *   r6 = size of decompressed image
 108                  *   r2 = end of malloc space (and therefore this image)
 109                  * We basically want:
 110                  *   r4 >= r2 -> OK
 111                  *   r4 + image length <= r5 -> OK
 112                  */
 113                 ldw     r4, =KERNEL_IMAGE_START
 114                 csub.a  r4, r2
 115                 bea     wont_overwrite
 116                 add     r0, r4, r6
 117                 csub.a  r0, r5
 118                 beb     wont_overwrite
 119
 120                 /*
 121                  * If overwrite, just print error message
 122                  */
 123                 b       __error_overwrite
 124
 125                 /*
 126                  * We're not in danger of overwriting ourselves.
 127                  * Do this the simple way.
 128                  */
 129 wont_overwrite:
 130                 /*
 131                  * decompress_kernel:
 132                  *   r0: output_start
 133                  *   r1: free_mem_ptr_p
 134                  *   r2: free_mem_ptr_end_p
 135                  */
 136                 mov     r0, r4
 137                 b.l     decompress_kernel       @ C functions
 138
 139                 /*
 140                  * Clean and flush the cache to maintain consistency.
 141                  */
 142                 mov     r0, #0
 143                 movc    p0.c5, r0, #14          @ flush dcache
 144                 nop8
 145                 movc    p0.c5, r0, #20          @ icache invalidate all
 146                 nop8
 147
 148                 /*
 149                  * Turn off the Cache and MMU.
 150                  */
 151                 mov     r0, #0                  @ disable i/d cache and MMU
 152                 movc    p0.c1, r0, #0
 153                 nop8
 154
 155                 mov     r0, #0                  @ must be zero
 156                 ldw     r4, =KERNEL_IMAGE_START
 157                 mov     pc, r4                  @ call kernel
 158
 159
 160                 .align  2
 161                 .type   LC0, #object
 162 LC0:            .word   LC0                     @ r1
 163                 .word   __bss_start             @ r2
 164                 .word   _end                    @ r3
 165                 .word   _start                  @ r5
 166                 .word   _image_size             @ r6
 167                 .word   _got_start              @ r7
 168                 .word   _got_end                @ r8
 169                 .word   decompress_stack_end    @ sp
 170                 .size   LC0, . - LC0
 171
 172 print_string:
 173 #ifdef CONFIG_DEBUG_OCD
 174 2001:           ldb.w   r1, [r0]+, #1
 175                 csub.a  r1, #0
 176                 bne     2002f
 177                 mov     pc, lr
 178 2002:
 179                 movc    r2, p1.c0, #0
 180                 cand.a  r2, #2
 181                 bne     2002b
 182                 movc    p1.c1, r1, #1
 183                 csub.a  r1, #'\n'
 184                 cmoveq  r1, #'\r'
 185                 beq     2002b
 186                 b       2001b
 187 #else
 188                 mov     pc, lr
 189 #endif
 190
 191 __error_overwrite:
 192                 adr     r0, str_error
 193                 b.l     print_string
 194 2001:           nop8
 195                 b       2001b
 196 str_error:      .asciz  "\nError: Kernel address OVERWRITE\n"
 197                 .align
 198
 199                 .ltorg
 200
 201                 .align  4
 202                 .section ".stack", "aw", %nobits
 203 decompress_stack:       .space  4096
 204 decompress_stack_end: