4fbbf651d7
__from_data16 and __from_text16 now take a pointer to a
.data16/.text16 variable, and return the real-mode offset within the
appropriate segment. This matches the use case for every occurrence
of these macros, and prevents potential future bugs such as that fixed
in commit d51d80f
. (The bug arose essentially because "&pointer" is
still syntactically valid.)
234 lines
6.8 KiB
C
234 lines
6.8 KiB
C
#ifndef LIBKIR_H
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#define LIBKIR_H
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#include "realmode.h"
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#ifndef ASSEMBLY
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/*
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* Full API documentation for these functions is in realmode.h.
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*
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*/
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/* Access to variables in .data16 and .text16 in a way compatible with librm */
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#define __data16( variable ) variable
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#define __data16_array( variable, array ) variable array
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#define __bss16( variable ) variable
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#define __bss16_array( variable, array ) variable array
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#define __text16( variable ) variable
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#define __text16_array( variable,array ) variable array
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#define __use_data16( variable ) variable
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#define __use_text16( variable ) variable
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#define __from_data16( pointer ) pointer
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#define __from_text16( pointer ) pointer
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/* Real-mode data and code segments */
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static inline __attribute__ (( always_inline )) unsigned int _rm_cs ( void ) {
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uint16_t cs;
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__asm__ __volatile__ ( "movw %%cs, %w0" : "=r" ( cs ) );
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return cs;
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}
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static inline __attribute__ (( always_inline )) unsigned int _rm_ds ( void ) {
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uint16_t ds;
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__asm__ __volatile__ ( "movw %%ds, %w0" : "=r" ( ds ) );
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return ds;
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}
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#define rm_cs ( _rm_cs() )
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#define rm_ds ( _rm_ds() )
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/* Copy to/from base memory */
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static inline void copy_to_real_libkir ( unsigned int dest_seg,
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unsigned int dest_off,
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const void *src, size_t n ) {
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unsigned int discard_D, discard_S, discard_c;
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__asm__ __volatile__ ( "pushw %%es\n\t"
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"movw %3, %%es\n\t"
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"rep movsb\n\t"
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"popw %%es\n\t"
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: "=D" ( discard_D ), "=S" ( discard_S ),
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"=c" ( discard_c )
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: "r" ( dest_seg ), "D" ( dest_off ),
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"S" ( src ),
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"c" ( n )
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: "memory" );
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}
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static inline void copy_from_real_libkir ( void *dest,
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unsigned int src_seg,
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unsigned int src_off,
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size_t n ) {
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unsigned int discard_D, discard_S, discard_c;
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__asm__ __volatile__ ( "pushw %%ds\n\t"
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"movw %4, %%ds\n\t"
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"rep movsb\n\t"
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"popw %%ds\n\t"
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: "=D" ( discard_D ), "=S" ( discard_S ),
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"=c" ( discard_c )
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: "D" ( dest ),
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"r" ( src_seg ), "S" ( src_off ),
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"c" ( n )
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: "memory" );
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}
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#define copy_to_real copy_to_real_libkir
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#define copy_from_real copy_from_real_libkir
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/*
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* Transfer individual values to/from base memory. There may well be
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* a neater way to do this. We have two versions: one for constant
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* offsets (where the mov instruction must be of the form "mov
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* %es:123, %xx") and one for non-constant offsets (where the mov
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* instruction must be of the form "mov %es:(%xx), %yx". If it's
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* possible to incorporate both forms into one __asm__ instruction, I
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* don't know how to do it.
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*
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* Ideally, the mov instruction should be "mov%z0"; the "%z0" is meant
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* to expand to either "b", "w" or "l" depending on the size of
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* operand 0. This would remove the (minor) ambiguity in the mov
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* instruction. However, gcc on at least my system barfs with an
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* "internal compiler error" when confronted with %z0.
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*
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*/
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#define put_real_kir_const_off( var, seg, off ) \
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__asm__ ( "movw %w1, %%es\n\t" \
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"mov %0, %%es:%c2\n\t" \
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"pushw %%ds\n\t" /* restore %es */ \
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"popw %%es\n\t" \
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: \
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: "r,r" ( var ), "rm,rm" ( seg ), "i,!r" ( off ) \
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)
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#define put_real_kir_nonconst_off( var, seg, off ) \
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__asm__ ( "movw %w1, %%es\n\t" \
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"mov %0, %%es:(%2)\n\t" \
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"pushw %%ds\n\t" /* restore %es */ \
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"popw %%es\n\t" \
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: \
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: "r" ( var ), "rm" ( seg ), "r" ( off ) \
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)
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#define put_real_kir( var, seg, off ) \
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do { \
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if ( __builtin_constant_p ( off ) ) \
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put_real_kir_const_off ( var, seg, off ); \
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else \
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put_real_kir_nonconst_off ( var, seg, off ); \
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} while ( 0 )
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#define get_real_kir_const_off( var, seg, off ) \
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__asm__ ( "movw %w1, %%es\n\t" \
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"mov %%es:%c2, %0\n\t" \
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"pushw %%ds\n\t" /* restore %es */ \
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"popw %%es\n\t" \
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: "=r,r" ( var ) \
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: "rm,rm" ( seg ), "i,!r" ( off ) \
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)
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#define get_real_kir_nonconst_off( var, seg, off ) \
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__asm__ ( "movw %w1, %%es\n\t" \
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"mov %%es:(%2), %0\n\t" \
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"pushw %%ds\n\t" /* restore %es */ \
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"popw %%es\n\t" \
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: "=r" ( var ) \
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: "rm" ( seg ), "r" ( off ) \
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)
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#define get_real_kir( var, seg, off ) \
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do { \
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if ( __builtin_constant_p ( off ) ) \
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get_real_kir_const_off ( var, seg, off ); \
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else \
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get_real_kir_nonconst_off ( var, seg, off ); \
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} while ( 0 )
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#define put_real put_real_kir
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#define get_real get_real_kir
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/**
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* A pointer to a user buffer
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*
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* This is actually a struct segoff, but encoded as a uint32_t to
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* ensure that gcc passes it around efficiently.
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*/
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typedef uint32_t userptr_t;
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/**
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* Copy data to user buffer
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*
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* @v buffer User buffer
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* @v offset Offset within user buffer
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* @v src Source
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* @v len Length
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*/
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static inline __attribute__ (( always_inline )) void
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copy_to_user ( userptr_t buffer, off_t offset, const void *src, size_t len ) {
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copy_to_real ( ( buffer >> 16 ), ( ( buffer & 0xffff ) + offset ),
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src, len );
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}
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/**
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* Copy data from user buffer
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*
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* @v dest Destination
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* @v buffer User buffer
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* @v offset Offset within user buffer
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* @v len Length
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*/
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static inline __attribute__ (( always_inline )) void
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copy_from_user ( void *dest, userptr_t buffer, off_t offset, size_t len ) {
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copy_from_real ( dest, ( buffer >> 16 ),
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( ( buffer & 0xffff ) + offset ), len );
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}
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/**
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* Convert segment:offset address to user buffer
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*
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* @v segment Real-mode segment
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* @v offset Real-mode offset
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* @ret buffer User buffer
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*/
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static inline __attribute__ (( always_inline )) userptr_t
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real_to_user ( unsigned int segment, unsigned int offset ) {
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return ( ( segment << 16 ) | offset );
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}
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/**
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* Convert virtual address to user buffer
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*
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* @v virtual Virtual address
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* @ret buffer User buffer
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*
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* This constructs a user buffer from an ordinary pointer. Use it
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* when you need to pass a pointer to an internal buffer to a function
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* that expects a @c userptr_t.
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*/
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static inline __attribute__ (( always_inline )) userptr_t
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virt_to_user ( void * virtual ) {
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return real_to_user ( rm_ds, ( intptr_t ) virtual );
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}
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/* TEXT16_CODE: declare a fragment of code that resides in .text16 */
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#define TEXT16_CODE( asm_code_str ) \
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".section \".text16\", \"ax\", @progbits\n\t" \
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".code16\n\t" \
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".arch i386\n\t" \
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asm_code_str "\n\t" \
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".code16gcc\n\t" \
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".previous\n\t"
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/* REAL_CODE: declare a fragment of code that executes in real mode */
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#define REAL_CODE( asm_code_str ) \
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".code16\n\t" \
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asm_code_str "\n\t" \
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".code16gcc\n\t"
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#endif /* ASSEMBLY */
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#endif /* LIBKIR_H */
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