/*
* linux/arch/unicore32/boot/compressed/head.S
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Copyright (C) 2001-2010 GUAN Xue-tao
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <mach/memory.h>
#define csub cmpsub
#define cand cmpand
#define nop8 nop; nop; nop; nop; nop; nop; nop; nop
.section ".start", #alloc, #execinstr
.text
start:
.type start,#function
/* Initialize ASR, PRIV mode and INTR off */
mov r0, #0xD3
mov.a asr, r0
adr r0, LC0
ldm (r1, r2, r3, r5, r6, r7, r8), [r0]+
ldw sp, [r0+], #28
sub.a r0, r0, r1 @ calculate the delta offset
/*
* if delta is zero, we are running at the address
* we were linked at.
*/
beq not_relocated
/*
* We're running at a different address. We need to fix
* up various pointers:
* r5 - zImage base address (_start)
* r7 - GOT start
* r8 - GOT end
*/
add r5, r5, r0
add r7, r7, r0
add r8, r8, r0
/*
* we need to fix up pointers into the BSS region.
* r2 - BSS start
* r3 - BSS end
* sp - stack pointer
*/
add r2, r2, r0
add r3, r3, r0
add sp, sp, r0
/*
* Relocate all entries in the GOT table.
* This fixes up the C references.
* r7 - GOT start
* r8 - GOT end
*/
1001: ldw r1, [r7+], #0
add r1, r1, r0
stw.w r1, [r7]+, #4
csub.a r7, r8
bub 1001b
not_relocated:
/*
* Clear BSS region.
* r2 - BSS start
* r3 - BSS end
*/
mov r0, #0
1002: stw.w r0, [r2]+, #4
csub.a r2, r3
bub 1002b
/*
* Turn on the cache.
*/
mov r0, #0
movc p0.c5, r0, #28 @ cache invalidate all
nop8
movc p0.c6, r0, #6 @ tlb invalidate all
nop8
mov r0, #0x1c @ en icache and wb dcache
movc p0.c1, r0, #0
nop8
/*
* Set up some pointers, for starting decompressing.
*/
mov r1, sp @ malloc space above stack
add r2, sp, #0x10000 @ 64k max
/*
* Check to see if we will overwrite ourselves.
* r4 = final kernel address
* r5 = start of this image
* r6 = size of decompressed image
* r2 = end of malloc space (and therefore this image)
* We basically want:
* r4 >= r2 -> OK
* r4 + image length <= r5 -> OK
*/
ldw r4, =KERNEL_IMAGE_START
csub.a r4, r2
bea wont_overwrite
add r0, r4, r6
csub.a r0, r5
beb wont_overwrite
/*
* If overwrite, just print error message
*/
b __error_overwrite
/*
* We're not in danger of overwriting ourselves.
* Do this the simple way.
*/
wont_overwrite:
/*
* decompress_kernel:
* r0: output_start
* r1: free_mem_ptr_p
* r2: free_mem_ptr_end_p
*/
mov r0, r4
b.l decompress_kernel @ C functions
/*
* Clean and flush the cache to maintain consistency.
*/
mov r0, #0
movc p0.c5, r0, #14 @ flush dcache
nop8
movc p0.c5, r0, #20 @ icache invalidate all
nop8
/*
* Turn off the Cache and MMU.
*/
mov r0, #0 @ disable i/d cache and MMU
movc p0.c1, r0, #0
nop8
mov r0, #0 @ must be zero
ldw r4, =KERNEL_IMAGE_START
mov pc, r4 @ call kernel
.align 2
.type LC0, #object
LC0: .word LC0 @ r1
.word __bss_start @ r2
.word _end @ r3
.word _start @ r5
.word _image_size @ r6
.word _got_start @ r7
.word _got_end @ r8
.word decompress_stack_end @ sp
.size LC0, . - LC0
print_string:
#ifdef [31mCONFIG_DEBUG_OCD[0m
2001: ldb.w r1, [r0]+, #1
csub.a r1, #0
bne 2002f
mov pc, lr
2002:
movc r2, p1.c0, #0
cand.a r2, #2
bne 2002b
movc p1.c1, r1, #1
csub.a r1, #'\n'
cmoveq r1, #'\r'
beq 2002b
b 2001b
#else
mov pc, lr
#endif
__error_overwrite:
adr r0, str_error
b.l print_string
2001: nop8
b 2001b
str_error: .asciz "\nError: Kernel address OVERWRITE\n"
.align
.ltorg
.align 4
.section ".stack", "aw", %nobits
decompress_stack: .space 4096
decompress_stack_end: