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