mirror of
https://github.com/xcat2/xNBA.git
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102 lines
2.2 KiB
ArmAsm
102 lines
2.2 KiB
ArmAsm
/*
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* Functions to support the virtual addressing method of relocation
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* that Etherboot uses.
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*
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*/
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#include "virtaddr.h"
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.arch i386
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.text
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.code32
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/****************************************************************************
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* _virt_to_phys (virtual addressing)
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*
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* Switch from virtual to flat physical addresses. %esp is adjusted
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* to a physical value. Segment registers are set to flat physical
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* selectors. All other registers are preserved. Flags are
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* preserved.
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*
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* Parameters: none
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* Returns: none
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****************************************************************************
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*/
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.globl _virt_to_phys
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_virt_to_phys:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Change return address to a physical address */
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movl virt_offset, %ebp
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addl %ebp, 12(%esp)
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/* Switch to physical code segment */
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pushl $PHYSICAL_CS
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leal 1f(%ebp), %eax
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pushl %eax
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lret
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1:
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/* Reload other segment registers and adjust %esp */
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movl $PHYSICAL_DS, %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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movl %eax, %ss
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addl %ebp, %esp
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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/****************************************************************************
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* _phys_to_virt (flat physical addressing)
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*
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* Switch from flat physical to virtual addresses. %esp is adjusted
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* to a virtual value. Segment registers are set to virtual
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* selectors. All other registers are preserved. Flags are
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* preserved.
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*
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* Note that this depends on the GDT already being correctly set up
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* (e.g. by a call to run_here()).
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*
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* Parameters: none
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* Returns: none
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****************************************************************************
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*/
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.globl _phys_to_virt
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_phys_to_virt:
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/* Preserve registers and flags */
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pushfl
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pushl %eax
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pushl %ebp
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/* Switch to virtual code segment */
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ljmp $VIRTUAL_CS, $1f
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1:
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/* Reload data segment registers */
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movl $VIRTUAL_DS, %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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/* Reload stack segment and adjust %esp */
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movl virt_offset, %ebp
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movl %eax, %ss
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subl %ebp, %esp
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/* Change the return address to a virtual address */
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subl %ebp, 12(%esp)
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/* Restore registers and flags, and return */
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popl %ebp
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popl %eax
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popfl
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ret
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