src/arch/i386/include/libkir.h

   1 #ifndef LIBKIR_H
   2 #define LIBKIR_H
   3
   4 #include "realmode.h"
   5
   6 #ifndef ASSEMBLY
   7
   8 /*
   9  * Full API documentation for these functions is in realmode.h.
  10  *
  11  */
  12
  13 /* Access to variables in .data16 and .text16 in a way compatible with librm */
  14 #define __data16( variable ) variable
  15 #define __data16_array( variable, array ) variable array
  16 #define __bss16( variable ) variable
  17 #define __bss16_array( variable, array ) variable array
  18 #define __text16( variable ) variable
  19 #define __text16_array( variable,array ) variable array
  20 #define __use_data16( variable ) variable
  21 #define __use_text16( variable ) variable
  22 #define __from_data16( pointer ) pointer
  23 #define __from_text16( pointer ) pointer
  24
  25 /* Real-mode data and code segments */
  26 static inline __attribute__ (( always_inline )) unsigned int _rm_cs ( void ) {
  27         uint16_t cs;
  28         __asm__ __volatile__ ( "movw %%cs, %w0" : "=r" ( cs ) );
  29         return cs;
  30 }
  31
  32 static inline __attribute__ (( always_inline )) unsigned int _rm_ds ( void ) {
  33         uint16_t ds;
  34         __asm__ __volatile__ ( "movw %%ds, %w0" : "=r" ( ds ) );
  35         return ds;
  36 }
  37
  38 #define rm_cs ( _rm_cs() )
  39 #define rm_ds ( _rm_ds() )
  40
  41 /* Copy to/from base memory */
  42
  43 static inline void copy_to_real_libkir ( unsigned int dest_seg,
  44                                          unsigned int dest_off,
  45                                          const void *src, size_t n ) {
  46         unsigned int discard_D, discard_S, discard_c;
  47
  48         __asm__ __volatile__ ( "pushw %%es\n\t"
  49                                "movw %3, %%es\n\t"
  50                                "rep movsb\n\t"
  51                                "popw %%es\n\t"
  52                                : "=D" ( discard_D ), "=S" ( discard_S ),
  53                                  "=c" ( discard_c )
  54                                : "r" ( dest_seg ), "D" ( dest_off ),
  55                                  "S" ( src ),
  56                                  "c" ( n )
  57                                : "memory" );
  58 }
  59
  60 static inline void copy_from_real_libkir ( void *dest,
  61                                            unsigned int src_seg,
  62                                            unsigned int src_off,
  63                                            size_t n ) {
  64         unsigned int discard_D, discard_S, discard_c;
  65
  66         __asm__ __volatile__ ( "pushw %%ds\n\t"
  67                                "movw %4, %%ds\n\t"
  68                                "rep movsb\n\t"
  69                                "popw %%ds\n\t"
  70                                : "=D" ( discard_D ), "=S" ( discard_S ),
  71                                  "=c" ( discard_c )
  72                                : "D" ( dest ),
  73                                  "r" ( src_seg ), "S" ( src_off ),
  74                                  "c" ( n )
  75                                : "memory" );
  76 }
  77
  78 #define copy_to_real copy_to_real_libkir
  79 #define copy_from_real copy_from_real_libkir
  80
  81 /*
  82  * Transfer individual values to/from base memory.  There may well be
  83  * a neater way to do this.  We have two versions: one for constant
  84  * offsets (where the mov instruction must be of the form "mov
  85  * %es:123, %xx") and one for non-constant offsets (where the mov
  86  * instruction must be of the form "mov %es:(%xx), %yx".  If it's
  87  * possible to incorporate both forms into one __asm__ instruction, I
  88  * don't know how to do it.
  89  *
  90  * Ideally, the mov instruction should be "mov%z0"; the "%z0" is meant
  91  * to expand to either "b", "w" or "l" depending on the size of
  92  * operand 0.  This would remove the (minor) ambiguity in the mov
  93  * instruction.  However, gcc on at least my system barfs with an
  94  * "internal compiler error" when confronted with %z0.
  95  *
  96  */
  97
  98 #define put_real_kir_const_off( var, seg, off )                              \
  99         __asm__ ( "movw %w1, %%es\n\t"                                       \
 100                   "mov %0, %%es:%c2\n\t"                                     \
 101                   "pushw %%ds\n\t" /* restore %es */                         \
 102                   "popw %%es\n\t"                                            \
 103                   :                                                          \
 104                   : "r,r" ( var ), "rm,rm" ( seg ), "i,!r" ( off )           \
 105                   )
 106
 107 #define put_real_kir_nonconst_off( var, seg, off )                           \
 108         __asm__ ( "movw %w1, %%es\n\t"                                       \
 109                   "mov %0, %%es:(%2)\n\t"                                    \
 110                   "pushw %%ds\n\t" /* restore %es */                         \
 111                   "popw %%es\n\t"                                            \
 112                   :                                                          \
 113                   : "r" ( var ), "rm" ( seg ), "r" ( off )                   \
 114                   )
 115
 116 #define put_real_kir( var, seg, off )                                        \
 117         do {                                                                 \
 118           if ( __builtin_constant_p ( off ) )                                \
 119                   put_real_kir_const_off ( var, seg, off );                  \
 120           else                                                               \
 121                   put_real_kir_nonconst_off ( var, seg, off );               \
 122         } while ( 0 )
 123
 124 #define get_real_kir_const_off( var, seg, off )                              \
 125         __asm__ ( "movw %w1, %%es\n\t"                                       \
 126                   "mov %%es:%c2, %0\n\t"                                     \
 127                   "pushw %%ds\n\t" /* restore %es */                         \
 128                   "popw %%es\n\t"                                            \
 129                   : "=r,r" ( var )                                           \
 130                   : "rm,rm" ( seg ), "i,!r" ( off )                          \
 131                   )
 132
 133 #define get_real_kir_nonconst_off( var, seg, off )                           \
 134         __asm__ ( "movw %w1, %%es\n\t"                                       \
 135                   "mov %%es:(%2), %0\n\t"                                    \
 136                   "pushw %%ds\n\t" /* restore %es */                         \
 137                   "popw %%es\n\t"                                            \
 138                   : "=r" ( var )                                             \
 139                   : "rm" ( seg ), "r" ( off )                                \
 140                   )
 141
 142 #define get_real_kir( var, seg, off )                                        \
 143         do {                                                                 \
 144           if ( __builtin_constant_p ( off ) )                                \
 145                   get_real_kir_const_off ( var, seg, off );                  \
 146           else                                                               \
 147                   get_real_kir_nonconst_off ( var, seg, off );               \
 148         } while ( 0 )
 149
 150 #define put_real put_real_kir
 151 #define get_real get_real_kir
 152
 153 /**
 154  * A pointer to a user buffer
 155  *
 156  * This is actually a struct segoff, but encoded as a uint32_t to
 157  * ensure that gcc passes it around efficiently.
 158  */
 159 typedef uint32_t userptr_t;
 160
 161 /**
 162  * Copy data to user buffer
 163  *
 164  * @v buffer    User buffer
 165  * @v offset    Offset within user buffer
 166  * @v src       Source
 167  * @v len       Length
 168  */
 169 static inline __attribute__ (( always_inline )) void
 170 copy_to_user ( userptr_t buffer, off_t offset, const void *src, size_t len ) {
 171         copy_to_real ( ( buffer >> 16 ), ( ( buffer & 0xffff ) + offset ),
 172                        src, len );
 173 }
 174
 175 /**
 176  * Copy data from user buffer
 177  *
 178  * @v dest      Destination
 179  * @v buffer    User buffer
 180  * @v offset    Offset within user buffer
 181  * @v len       Length
 182  */
 183 static inline __attribute__ (( always_inline )) void
 184 copy_from_user ( void *dest, userptr_t buffer, off_t offset, size_t len ) {
 185         copy_from_real ( dest, ( buffer >> 16 ),
 186                          ( ( buffer & 0xffff ) + offset ), len );
 187 }
 188
 189 /**
 190  * Convert segment:offset address to user buffer
 191  *
 192  * @v segment   Real-mode segment
 193  * @v offset    Real-mode offset
 194  * @ret buffer  User buffer
 195  */
 196 static inline __attribute__ (( always_inline )) userptr_t
 197 real_to_user ( unsigned int segment, unsigned int offset ) {
 198         return ( ( segment << 16 ) | offset );
 199 }
 200
 201 /**
 202  * Convert virtual address to user buffer
 203  *
 204  * @v virtual   Virtual address
 205  * @ret buffer  User buffer
 206  *
 207  * This constructs a user buffer from an ordinary pointer.  Use it
 208  * when you need to pass a pointer to an internal buffer to a function
 209  * that expects a @c userptr_t.
 210  */
 211 static inline __attribute__ (( always_inline )) userptr_t
 212 virt_to_user ( void * virtual ) {
 213         return real_to_user ( rm_ds, ( intptr_t ) virtual );
 214 }
 215
 216 /* TEXT16_CODE: declare a fragment of code that resides in .text16 */
 217 #define TEXT16_CODE( asm_code_str )                     \
 218         ".section \".text16\", \"ax\", @progbits\n\t"   \
 219         ".code16\n\t"                                   \
 220         ".arch i386\n\t"                                \
 221         asm_code_str "\n\t"                             \
 222         ".code16gcc\n\t"                                \
 223         ".previous\n\t"
 224
 225 /* REAL_CODE: declare a fragment of code that executes in real mode */
 226 #define REAL_CODE( asm_code_str )       \
 227         ".code16\n\t"                   \
 228         asm_code_str "\n\t"             \
 229         ".code16gcc\n\t"
 230
 231 #endif /* ASSEMBLY */
 232
 233 #endif /* LIBKIR_H */