ldtmanag.c

freedos32的源代码

}


/* fd32_set_segment_limit - Implementation of DPMI 0.9 service 0008h
 *                          "Set Segment Limit"
 *
 * This code is based on CWSDPMI 5.0, file exphdlr.c
 * by Salvo Isaja
 *
 * FIX ME: DPMI Specifications indicate the following error codes to return
 *         that are currently not considered (by CWSDPMI too, however):
 *
 *           8021h  invalid value (CX <> 0 on a 16-bit DPMI host; or the
 *                  limit is greater than 1 MB, but the low twelve bits are
 *                  not set)
 *           8025h  invalid linear address (changing the limit would cause
 *                  the descriptor to reference a linear address range
 *                  outside that allowed for DPMI clients.)
 *
 * FIX ME: The DPMI Specifications say also that:
 *         A DPMI 1.0 host will reload any segment registers which contain
 *         the selector specified in register BX. It is suggested that
 *         DPMI 0.9 hosts also implement this.
 */
int fd32_set_segment_limit(WORD Selector, DWORD Limit)
{
  WORD i,j,k;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Set Segment Limit: Selector 0x%x  Limit 0x%lx\n",Selector,Limit);
#endif

  ErrorCode = sel_to_ldt_index(Selector, &i);
  if (ErrorCode < 0) {
    return ErrorCode;
  }

  j = (WORD) Limit;
  k = Limit >> 16;

  if (k > 0xF)
  {
    j = (j >> 12) | (k << 4);
    k = 0x80 | (k >> 12);
  }

  DESCRIPTOR_TABLE(i).lim_lo  = j;
  DESCRIPTOR_TABLE(i).gran   &= 0x70;
  DESCRIPTOR_TABLE(i).gran   |= k;

  return NO_ERROR;
}


/* fd32_set_descriptor_access_rights - Implementation of DPMI 0.9 service 0009h
 *                                     "Set Descriptor Access Rights"
 *
 * This code is based on CWSDPMI 5.0, file exphdlr.c
 * by Salvo Isaja
 *
 * FIX ME: DPMI Specifications indicate the following error codes to return
 *         that are currently not considered (by CWSDPMI too, however):
 *
 *           8021h  invalid value (access rights/type bytes invalid)
 *           8025h  invalid linear address (changing the access rights/type
 *                  bytes would cause the descriptor to reference a linear
 *                  address range outside that allowed for DPMI clients.)
 *
 * FIX ME: The DPMI Specifications say also that:
 *         A DPMI 1.0 host will reload any segment registers which contain
 *         the selector specified in register BX. It is suggested that
 *         DPMI 0.9 hosts also implement this.
 */
int fd32_set_descriptor_access_rights(WORD Selector, WORD Rights)
{
  WORD i;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Set Descriptor Access Rights: Selector 0x%x   Rights 0x%x\n", Selector, Rights);
#endif

  ErrorCode = sel_to_ldt_index(Selector,&i);
  if (ErrorCode < 0) {
    return ErrorCode;
  }

  DESCRIPTOR_TABLE(i).access = 0x10 | (BYTE) Rights;
  DESCRIPTOR_TABLE(i).gran   = (0x0F & DESCRIPTOR_TABLE(i).gran) | ((Rights >> 8) & 0xD0);

  return NO_ERROR;
}


/* fd32_create_alias_descriptor - Implementation of DPMI 0.9 service 000Ah
 *                                "Create Alias Descriptor"
 *
 * This code is based on CWSDPMI 5.0, file exphdlr.c
 * by Salvo Isaja
 */
int fd32_create_alias_descriptor(WORD Selector)
{
  WORD Source, Dest, new_selector;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Create Alias Descriptor: Selector 0x%x\n", Selector);
#endif

  ErrorCode = sel_to_ldt_index(Selector, &Source);
  if (ErrorCode < 0) return ErrorCode;

  ErrorCode = fd32_allocate_descriptors(1);
  if (ErrorCode < 0) return ErrorCode;
  Dest = ErrorCode;
  /* We can safely ignore the exit code of the following */
  sel_to_ldt_index(Dest,&Dest);

  new_selector = INDEX_TO_SELECTOR(Dest);
  DESCRIPTOR_TABLE(Dest) = DESCRIPTOR_TABLE(Source);
  /* Data, exp-up, wrt */
  DESCRIPTOR_TABLE(Dest).access = 2 | (DESCRIPTOR_TABLE(Dest).access & 0xF0);

  return new_selector;
}


/* fd32_get_descriptor - Implementation of DPMI 0.9 service 000Bh
 *                       "Get Descriptor"
 *
 * FIX ME: CWSDPMI performs a check on the address of the destination
 *         buffer that I've ignored for simplicity.
 *         CWSDPMI also performs a more complicated copy process that
 *         is still unknown to me.
 *
 * This code is based on CWSDPMI 5.0, file exphdlr.c
 * by Salvo Isaja
 */
int fd32_get_descriptor(WORD Selector, WORD BufferSelector, DWORD BufferOffset)
{
  WORD i;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Get Descriptor: Selector 0x%x   Buffer: 0x%x:0x%lx\n",
                  Selector, BufferSelector, BufferOffset);
#endif

  /* TO DO: CHECK_POINTER(tss_ptr->tss_es, tss_ptr->tss_edi); */

  ErrorCode = sel_to_ldt_index(Selector, &i);
  if (ErrorCode < 0) return ErrorCode;

  /* The following assembly code copies the descriptor into */
  /* the buffer pointed by the specified 48-bit pointer.    */
  asm("push   %%es               \n"
      "mov    %%ax,%%es          \n"
      "mov    (%%ebx),%%edx      \n"
      "mov    %%edx,%%es:(%%edi) \n"
      "mov    4(%%ebx),%%edx     \n"
      "mov    %%edx,%%es:4(%%edi)\n"
      "pop    %%es               \n"
      :
      : "b" (&DESCRIPTOR_TABLE(i)), "a" (BufferSelector), "D" (BufferOffset)
      : "edx");
  return NO_ERROR;
}


/* fd32_set_descriptor - Implementation of DPMI 0.9 service 000Ch
 *                       "Set Descriptor"
 *
 * FIX ME: CWSDPMI performs a check on the address of the destination
 *         buffer that I've ignored for simplicity.
 *         CWSDPMI also performs a more complicated copy process that
 *         is still unknown to me.
 *
 * FIX ME: DPMI Specifications indicate the following error codes to return
 *         that are currently not considered (by CWSDPMI too, however):
 *
 *           8021h  invalid value (access rights/type bytes invalid)
 *           8025h  invalid linear address (descriptor references a linear
 *                  address range outside that allowed for DPMI clients)
 *
 * FIX ME: The DPMI Specifications say also that:
 *         "If the descriptor's present bit is not set, then the only error
 *          checking is that the client's CPL must be equal to the
 *          descriptor's DPL field and the "must be 1" bit in the descriptor's
 *          byte 5 must be set."
 *         This check is currently not performed by FD32 nor by CWSDPMI.
 *
 * FIX ME: The DPMI Specifications say also that:
 *         A DPMI 1.0 host will reload any segment registers which contain
 *         the selector specified in register BX. It is suggested that
 *         DPMI 0.9 hosts also implement this.
 *
 * This code is based on CWSDPMI 5.0, file exphdlr.c
 * by Salvo Isaja
 */
int fd32_set_descriptor(WORD Selector, WORD BufferSelector, DWORD BufferOffset)
{
  WORD i;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Set Descriptor: Selector 0x%x   Buffer: 0x%x:0x%lx\n",
                  Selector, BufferSelector, BufferOffset);
#endif

  /* TO DO: CHECK_POINTER(tss_ptr->tss_es, tss_ptr->tss_edi); */

  ErrorCode = sel_to_ldt_index(Selector, &i);
  if (ErrorCode < 0) return ErrorCode;

  /* The following assembly code copies the buffer pointed */
  /* by the specified 48-bit pointer into the descriptor.  */
  asm("push   %%es               \n"
      "mov    %%ax,%%es          \n"
      "mov    %%es:(%%ebx),%%edx \n"
      "mov    %%edx,(%%edi)      \n"
      "mov    %%es:4(%%ebx),%%edx\n"
      "mov    %%edx,4(%%edi)     \n"
      "pop    %%es               \n"
      :
      : "D" (&DESCRIPTOR_TABLE(i)), "a" (BufferSelector), "b" (BufferOffset)
      : "edx");
  DESCRIPTOR_TABLE(i).access |= 0x10; /* Make sure non-system, non-zero */
  return NO_ERROR;
}


/* fd32_get_multiple_descriptors - Implementation of DPMI 1.0 service 000Eh
 *                                 "Get Multiple Descriptors"
 * by Salvo Isaja
 */
int fd32_get_multiple_descriptors(WORD Descriptors, WORD BufferSelector, DWORD BufferOffset)
{
  WORD i;
  WORD Selector;
  int  Count;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Get Multiple Descriptor: Descriptors: 0x%x   Buffer: 0x%x:0x%lx\n",
                  Descriptors, BufferSelector, BufferOffset);
#endif

  /* TO DO: CHECK_POINTER(tss_ptr->tss_es, tss_ptr->tss_edi); */

  asm("push %%fs     \n"
      "mov  %%ax,%%fs\n"
      :
      : "a" (BufferSelector));

  for (Count = 0; Count < Descriptors; Count++)
  {
    asm("mov %%fs:(%%edi),%%ax"
        : "=a" (Selector)
        : "D" (BufferOffset));

    ErrorCode = sel_to_ldt_index(Selector, &i);
    if (ErrorCode < 0) return ErrorCode; /* FIX ME: Should return Count */

    asm("mov (%%ebx),%%eax      \n"
        "mov %%eax,%%fs:2(%%edi)\n"
        "mov 4(%%ebx),%%eax     \n"
        "mov %%eax,%%fs:6(%%edi)\n"
        :
        : "b" (&DESCRIPTOR_TABLE(i)), "D" (BufferOffset)
        : "eax");
    BufferOffset += 10;
  }
  asm("pop %fs");
  return NO_ERROR;
}


/* fd32_set_multiple_descriptors - Implementation of DPMI 1.0 service 000Fh
 *                                 "Set Multiple Descriptors"
 * by Salvo Isaja
 *
 * FIX ME: DPMI Specifications indicate the following error codes to return
 *         that are currently not considered:
 *
 *           8021h  invalid value (access rights/type bytes invalid)
 *           8025h  invalid linear address (descriptor references a linear
 *                  address range outside that allowed for DPMI clients)
 *
 * FIX ME: The DPMI Specifications say also that:
 *         "If the descriptor's present bit is not set, then the only error
 *          checking is that the client's CPL must be equal to the
 *          descriptor's DPL field and the "must be 1" bit in the descriptor's
 *          byte 5 must be set."
 *         This check is currently not performed.
 *
 * FIX ME: The DPMI Specifications say also that:
 *         A DPMI 1.0 host will reload any segment registers which contain
 *         the selector specified in register BX. It is suggested that
 *         DPMI 0.9 hosts also implement this.
 */
int fd32_set_multiple_descriptors(WORD Descriptors, WORD BufferSelector, DWORD BufferOffset)
{
  WORD i;
  WORD Selector;
  int  Count;
  int  ErrorCode;

#ifdef __DEBUG__
  fd32_log_printf("[DPMI] Set Multiple Descriptor: Descriptors: 0x%x   Buffer: 0x%x:0x%lx\n",
                  Descriptors, BufferSelector, BufferOffset);
#endif

  /* TO DO: CHECK_POINTER(tss_ptr->tss_es, tss_ptr->tss_edi); */

  asm("push %%fs     \n"
      "mov  %%ax,%%fs\n"
      :
      : "a" (BufferSelector));

  for (Count = 0; Count < Descriptors; Count++)
  {
    asm("mov %%fs:(%%ebx),%%ax"
        : "=a" (Selector)
        : "b" (BufferOffset));

    ErrorCode = sel_to_ldt_index(Selector, &i);
    if (ErrorCode < 0) return ErrorCode; /* FIX ME: Should return Count */

    asm("mov %%fs:2(%%ebx),%%eax\n"
        "mov %%eax,(%%edi)      \n"
        "mov %%fs:6(%%ebx),%%eax\n"
        "mov %%eax,4(%%edi)     \n"
        :
        : "b" (BufferOffset), "D" (&DESCRIPTOR_TABLE(i))
        : "eax");
    BufferOffset += 10;
    DESCRIPTOR_TABLE(i).access |= 0x10; /* Make sure non-system, non-zero */
  }
  asm("pop %fs");
  return NO_ERROR;
}