e5a2072bd4
This patch adds a reg.h to the zImage code, with common definitions for accessing system registers. For now, this includes functions for retrieving the PVR and the stack pointer. This patch then uses the new reg.h to let start() display the running stack address without having to explicitly pass the stack as a parameter from the asm code. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>
92 lines
1.9 KiB
ArmAsm
92 lines
1.9 KiB
ArmAsm
/*
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* Copyright (C) Paul Mackerras 1997.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* NOTE: this code runs in 32 bit mode and is packaged as ELF32.
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*/
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#include "ppc_asm.h"
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.text
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/* a procedure descriptor used when booting this as a COFF file */
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_zimage_start_opd:
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.long _zimage_start, 0, 0, 0
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.weak _zimage_start
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.globl _zimage_start
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_zimage_start:
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.globl _zimage_start_lib
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_zimage_start_lib:
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/* Work out the offset between the address we were linked at
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and the address where we're running. */
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bl 1f
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1: mflr r0
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lis r9,1b@ha
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addi r9,r9,1b@l
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subf. r0,r9,r0
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beq 3f /* if running at same address as linked */
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/* The .got2 section contains a list of addresses, so add
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the address offset onto each entry. */
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lis r9,__got2_start@ha
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addi r9,r9,__got2_start@l
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lis r8,__got2_end@ha
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addi r8,r8,__got2_end@l
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subf. r8,r9,r8
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beq 3f
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srwi. r8,r8,2
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mtctr r8
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add r9,r0,r9
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2: lwz r8,0(r9)
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add r8,r8,r0
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stw r8,0(r9)
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addi r9,r9,4
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bdnz 2b
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/* Do a cache flush for our text, in case the loader didn't */
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3: lis r9,_start@ha
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addi r9,r9,_start@l
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add r9,r0,r9
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lis r8,_etext@ha
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addi r8,r8,_etext@l
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add r8,r0,r8
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4: dcbf r0,r9
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icbi r0,r9
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addi r9,r9,0x20
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cmplw cr0,r9,r8
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blt 4b
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sync
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isync
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/* Clear the BSS */
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lis r9,__bss_start@ha
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addi r9,r9,__bss_start@l
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lis r8,_end@ha
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addi r8,r8,_end@l
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li r0,0
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5: stw r0,0(r9)
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addi r9,r9,4
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cmplw cr0,r9,r8
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blt 5b
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/* Possibly set up a custom stack */
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.weak _platform_stack_top
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lis r8,_platform_stack_top@ha
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addi r8,r8,_platform_stack_top@l
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cmpwi r8,0
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beq 6f
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lwz r1,0(r8)
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li r0,0
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stwu r0,-16(r1) /* establish a stack frame */
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6:
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/* Call platform_init() */
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bl platform_init
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/* Call start */
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b start
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