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

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * linux/arch/unicore32/boot/compressed/head.S
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  * Copyright (C) 2001-2010 GUAN Xue-tao
   8  */
   9 #include <linux/linkage.h>
  10 #include <mach/memory.h>
  11 
  12 #define csub    cmpsub
  13 #define cand    cmpand
  14 #define nop8    nop; nop; nop; nop; nop; nop; nop; nop
  15 
  16                 .section ".start", #alloc, #execinstr
  17                 .text
  18 start:
  19                 .type   start,#function
  20 
  21                 /* Initialize ASR, PRIV mode and INTR off */
  22                 mov     r0, #0xD3
  23                 mov.a   asr, r0
  24 
  25                 adr     r0, LC0
  26                 ldm     (r1, r2, r3, r5, r6, r7, r8), [r0]+
  27                 ldw     sp, [r0+], #28
  28                 sub.a   r0, r0, r1              @ calculate the delta offset
  29 
  30                 /*
  31                  * if delta is zero, we are running at the address
  32                  * we were linked at.
  33                  */
  34                 beq     not_relocated
  35 
  36                 /*
  37                  * We're running at a different address.  We need to fix
  38                  * up various pointers:
  39                  *   r5 - zImage base address (_start)
  40                  *   r7 - GOT start
  41                  *   r8 - GOT end
  42                  */
  43                 add     r5, r5, r0
  44                 add     r7, r7, r0
  45                 add     r8, r8, r0
  46 
  47                 /*
  48                  * we need to fix up pointers into the BSS region.
  49                  *   r2 - BSS start
  50                  *   r3 - BSS end
  51                  *   sp - stack pointer
  52                  */
  53                 add     r2, r2, r0
  54                 add     r3, r3, r0
  55                 add     sp, sp, r0
  56 
  57                 /*
  58                  * Relocate all entries in the GOT table.
  59                  * This fixes up the C references.
  60                  *   r7 - GOT start
  61                  *   r8 - GOT end
  62                  */
  63 1001:           ldw     r1, [r7+], #0
  64                 add     r1, r1, r0
  65                 stw.w   r1, [r7]+, #4
  66                 csub.a  r7, r8
  67                 bub     1001b
  68 
  69 not_relocated:
  70                 /*
  71                  * Clear BSS region.
  72                  *   r2 - BSS start
  73                  *   r3 - BSS end
  74                  */
  75                 mov     r0, #0
  76 1002:           stw.w   r0, [r2]+, #4
  77                 csub.a  r2, r3
  78                 bub     1002b
  79 
  80                 /*
  81                  * Turn on the cache.
  82                  */
  83                 mov     r0, #0
  84                 movc    p0.c5, r0, #28          @ cache invalidate all
  85                 nop8
  86                 movc    p0.c6, r0, #6           @ tlb invalidate all
  87                 nop8
  88 
  89                 mov     r0, #0x1c               @ en icache and wb dcache
  90                 movc    p0.c1, r0, #0
  91                 nop8
  92 
  93                 /*
  94                  * Set up some pointers, for starting decompressing.
  95                  */
  96 
  97                 mov     r1, sp                  @ malloc space above stack
  98                 add     r2, sp, #0x10000        @ 64k max
  99 
 100                 /*
 101                  * Check to see if we will overwrite ourselves.
 102                  *   r4 = final kernel address
 103                  *   r5 = start of this image
 104                  *   r6 = size of decompressed image
 105                  *   r2 = end of malloc space (and therefore this image)
 106                  * We basically want:
 107                  *   r4 >= r2 -> OK
 108                  *   r4 + image length <= r5 -> OK
 109                  */
 110                 ldw     r4, =KERNEL_IMAGE_START
 111                 csub.a  r4, r2
 112                 bea     wont_overwrite
 113                 add     r0, r4, r6
 114                 csub.a  r0, r5
 115                 beb     wont_overwrite
 116 
 117                 /*
 118                  * If overwrite, just print error message
 119                  */
 120                 b       __error_overwrite
 121 
 122                 /*
 123                  * We're not in danger of overwriting ourselves.
 124                  * Do this the simple way.
 125                  */
 126 wont_overwrite:
 127                 /*
 128                  * decompress_kernel:
 129                  *   r0: output_start
 130                  *   r1: free_mem_ptr_p
 131                  *   r2: free_mem_ptr_end_p
 132                  */
 133                 mov     r0, r4
 134                 b.l     decompress_kernel       @ C functions
 135 
 136                 /*
 137                  * Clean and flush the cache to maintain consistency.
 138                  */
 139                 mov     r0, #0
 140                 movc    p0.c5, r0, #14          @ flush dcache
 141                 nop8
 142                 movc    p0.c5, r0, #20          @ icache invalidate all
 143                 nop8
 144 
 145                 /*
 146                  * Turn off the Cache and MMU.
 147                  */
 148                 mov     r0, #0                  @ disable i/d cache and MMU
 149                 movc    p0.c1, r0, #0
 150                 nop8
 151 
 152                 mov     r0, #0                  @ must be zero
 153                 ldw     r4, =KERNEL_IMAGE_START
 154                 mov     pc, r4                  @ call kernel
 155 
 156 
 157                 .align  2
 158                 .type   LC0, #object
 159 LC0:            .word   LC0                     @ r1
 160                 .word   __bss_start             @ r2
 161                 .word   _end                    @ r3
 162                 .word   _start                  @ r5
 163                 .word   _image_size             @ r6
 164                 .word   _got_start              @ r7
 165                 .word   _got_end                @ r8
 166                 .word   decompress_stack_end    @ sp
 167                 .size   LC0, . - LC0
 168 
 169 print_string:
 170 #ifdef CONFIG_DEBUG_OCD
 171 2001:           ldb.w   r1, [r0]+, #1
 172                 csub.a  r1, #0
 173                 bne     2002f
 174                 mov     pc, lr
 175 2002:
 176                 movc    r2, p1.c0, #0
 177                 cand.a  r2, #2
 178                 bne     2002b
 179                 movc    p1.c1, r1, #1
 180                 csub.a  r1, #'\n'
 181                 cmoveq  r1, #'\r'
 182                 beq     2002b
 183                 b       2001b
 184 #else
 185                 mov     pc, lr
 186 #endif
 187 
 188 __error_overwrite:
 189                 adr     r0, str_error
 190                 b.l     print_string
 191 2001:           nop8
 192                 b       2001b
 193 str_error:      .asciz  "\nError: Kernel address OVERWRITE\n"
 194                 .align
 195 
 196                 .ltorg
 197 
 198                 .align  4
 199                 .section ".stack", "aw", %nobits
 200 decompress_stack:       .space  4096
 201 decompress_stack_end: