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author | fishsoupisgood <github@madingley.org> | 2019-04-29 01:17:54 +0100 |
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committer | fishsoupisgood <github@madingley.org> | 2019-05-27 03:43:43 +0100 |
commit | 3f2546b2ef55b661fd8dd69682b38992225e86f6 (patch) | |
tree | 65ca85f13617aee1dce474596800950f266a456c /roms/ipxe/src/arch/i386/core/virtaddr.S | |
download | qemu-master.tar.gz qemu-master.tar.bz2 qemu-master.zip |
Diffstat (limited to 'roms/ipxe/src/arch/i386/core/virtaddr.S')
-rw-r--r-- | roms/ipxe/src/arch/i386/core/virtaddr.S | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/roms/ipxe/src/arch/i386/core/virtaddr.S b/roms/ipxe/src/arch/i386/core/virtaddr.S new file mode 100644 index 00000000..5e5d7735 --- /dev/null +++ b/roms/ipxe/src/arch/i386/core/virtaddr.S @@ -0,0 +1,145 @@ +/* + * Functions to support the virtual addressing method of relocation + * that Etherboot uses. + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ) + +#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 */ + cli + 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. + * + * 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 */ + cli + 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 + +/**************************************************************************** + * _intr_to_virt (virtual code segment, virtual or physical stack segment) + * + * Switch from virtual code segment with either a virtual or physical + * stack segment to using virtual addressing. %esp is adjusted if + * necessary to a virtual value. Segment registers are set to virtual + * selectors. All other registers are preserved. Flags are + * preserved. + * + * Parameters: none + * Returns: none + **************************************************************************** + */ + .globl _intr_to_virt +_intr_to_virt: + /* Preserve registers and flags */ + pushfl + pushl %eax + pushl %ebp + + /* Check whether stack segment is physical or virtual */ + movl %ss, %eax + cmpw $VIRTUAL_DS, %ax + movl $VIRTUAL_DS, %eax + + /* Reload data segment registers */ + movl %eax, %ds + movl %eax, %es + movl %eax, %fs + movl %eax, %gs + + /* Reload stack segment and adjust %esp if necessary */ + je 1f + movl virt_offset, %ebp + movl %eax, %ss + subl %ebp, %esp +1: + /* Restore registers and flags, and return */ + popl %ebp + popl %eax + popfl + ret |