86 lines
2.4 KiB
C
86 lines
2.4 KiB
C
#ifndef VIRTADDR_H
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#define VIRTADDR_H
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/* Segment selectors as used in our protected-mode GDTs.
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*
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* Don't change these unless you really know what you're doing.
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*/
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#define PHYSICAL_CS 0x08
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#define PHYSICAL_DS 0x10
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#define VIRTUAL_CS 0x18
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#define VIRTUAL_DS 0x20
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#define LONG_CS 0x28
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#define LONG_DS 0x30
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#ifndef ASSEMBLY
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#include "stdint.h"
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#ifndef KEEP_IT_REAL
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/*
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* Without -DKEEP_IT_REAL, we are in 32-bit protected mode with a
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* fixed link address but an unknown physical start address. Our GDT
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* sets up code and data segments with an offset of virt_offset, so
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* that link-time addresses can still work.
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*
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*/
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/* C-callable function prototypes */
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extern void relocate_to ( uint32_t new_phys_addr );
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/* Variables in virtaddr.S */
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extern unsigned long virt_offset;
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/*
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* Convert between virtual and physical addresses
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*
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*/
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static inline unsigned long virt_to_phys ( volatile const void *virt_addr ) {
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return ( ( unsigned long ) virt_addr ) + virt_offset;
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}
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static inline void * phys_to_virt ( unsigned long phys_addr ) {
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return ( void * ) ( phys_addr - virt_offset );
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}
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#else /* KEEP_IT_REAL */
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/*
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* With -DKEEP_IT_REAL, we are in 16-bit real mode with fixed link
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* addresses and a segmented memory model. We have separate code and
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* data segments.
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*
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* Because we may be called in 16-bit protected mode (damn PXE spec),
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* we cannot simply assume that physical = segment * 16 + offset.
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* Instead, we have to look up the physical start address of the
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* segment in the !PXE structure. We have to assume that
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* virt_to_phys() is called only on pointers within the data segment,
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* because nothing passes segment information to us.
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*
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* We don't implement phys_to_virt at all, because there will be many
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* addresses that simply cannot be reached via a virtual address when
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* the virtual address space is limited to 64kB!
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*/
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static inline unsigned long virt_to_phys ( volatile const void *virt_addr ) {
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/* Cheat: just for now, do the segment*16+offset calculation */
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uint16_t ds;
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__asm__ ( "movw %%ds, %%ax" : "=a" ( ds ) : );
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return ( 16 * ds + ( ( unsigned long ) virt_addr ) );
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}
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/* Define it as a deprecated function so that we get compile-time
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* warnings, rather than just the link-time errors.
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*/
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extern void * phys_to_virt ( unsigned long phys_addr )
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__attribute__ ((deprecated));
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#endif /* KEEP_IT_REAL */
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#endif /* ASSEMBLY */
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#endif /* VIRTADDR_H */
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