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/*[
c_bsic.c
LOCAL CHAR SccsID[]="@(#)c_bsic.c 1.7 09/20/94";
Basic Protected Mode Support and Flag Support.
----------------------------------------------
]*/
#include <insignia.h>
#include <host_def.h>
#include <xt.h>
#include <c_main.h>
#include <c_addr.h>
#include <c_bsic.h>
#include <c_prot.h>
#include <c_seg.h>
#include <c_stack.h>
#include <c_xcptn.h>
#include <c_reg.h>
#include <c_page.h>
/*
=====================================================================
EXTERNAL ROUTINES START HERE.
=====================================================================
*/
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Determine 'super' type from access rights. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL ISM32
descriptor_super_type
IFN1(
IU16, AR /* (I) access rights */
)
{
ISM32 super;
switch ( super = GET_AR_SUPER(AR) )
{
case 0x0: case 0x8: case 0xa: case 0xd:
/* We have just one bad case */
return INVALID;
case 0x1: case 0x2: case 0x3:
case 0x4: case 0x5: case 0x6: case 0x7:
case 0x9: case 0xb: case 0xc: case 0xe: case 0xf:
/* system/control segments have one to one mapping */
return super;
case 0x10: case 0x11: case 0x12: case 0x13:
case 0x14: case 0x15: case 0x16: case 0x17:
case 0x18: case 0x19: case 0x1a: case 0x1b:
case 0x1c: case 0x1d: case 0x1e: case 0x1f:
/* data/code segments map as if accessed */
return super | ACCESSED;
}
/* We 'know' we never get here, but the C compiler doesn't */
return 0;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Set OF flag after multiple shift or rotate instruction. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
do_multiple_shiftrot_of
IFN1(
ISM32, new_of /* (I) overflow that would be written by last bit
shift or rotate */
)
{
SAVED IBOOL cold = TRUE;
SAVED IBOOL shiftrot_of_undef = FALSE;
if( cold )
{
/*
* Determine whether to have the multiple shift/rotates
* OF undefined or calculated by the count == 1 algorithm.
* The default is the count == 1 option.
*/
shiftrot_of_undef = ( host_getenv( "SHIFTROT_OF_UNDEF" ) != NULL );
cold = FALSE;
}
/*
There are three possible actions:-
1) Set OF based on the last bit shift or rotate.
2) Leave OF unchanged
3) Set OF to a specific undefined value.
*/
if( shiftrot_of_undef )
{
/* Set undefined flag(s) */
SET_OF(UNDEFINED_FLAG);
}
else
{
/* Just like count of one case */
SET_OF(new_of);
}
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Retrieve Intel EFLAGS register value */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL IU32
c_getEFLAGS IFN0()
{
IU32 flags;
flags = getFLAGS(); /* get lower word */
flags = flags | GET_VM() << 17 | GET_RF() << 16;
#ifdef SPC486
flags = flags | GET_AC() << 18;
#endif /* SPC486 */
return flags;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Retrieve Intel FLAGS register value */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL IU32
getFLAGS()
{
IU32 flags;
flags = GET_NT() << 14 | GET_IOPL() << 12 | GET_OF() << 11 |
GET_DF() << 10 | GET_IF() << 9 | GET_TF() << 8 |
GET_SF() << 7 | GET_ZF() << 6 | GET_AF() << 4 |
GET_PF() << 2 | GET_CF() | 0x2;
return flags;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Read a descriptor table at given linear address. */
/* Take #PF if descriptor not in linear address space. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
read_descriptor_linear
IFN2(
IU32, addr, /* (I) Linear address of descriptor */
CPU_DESCR *, descr /* (O) Pntr to our internal descriptor structure */
)
{
IU32 first_dword;
IU32 second_dword;
IU32 limit;
/*
The format of a 286 descriptor is:-
===========================
+1 | LIMIT 15-0 | +0
===========================
+3 | BASE 15-0 | +2
===========================
+5 | AR | BASE 23-16 | +4
===========================
+7 | RESERVED | +6
===========================
*/
/*
The format of a 386 descriptor is:-
============================= AR = Access Rights.
+1 | LIMIT 15-0 | +0 AVL = Available.
============================= D = Default Operand
+3 | BASE 15-0 | +2 Size, = 0 16-bit
============================= = 1 32-bit.
+5 | AR | BASE 23-16 | +4 G = Granularity,
============================= = 0 byte limit
| | | | |A|LIMIT| = 1 page limit.
+7 | BASE 31-24 |G|D|0|V|19-16| +6
| | | | |L| |
=============================
*/
/* read in descriptor with minimum interaction with memory */
first_dword = spr_read_dword(addr);
second_dword = spr_read_dword(addr+4);
/* load attributes and access rights */
descr->AR = second_dword >> 8 & WORD_MASK;
/* unpack the base */
descr->base = (first_dword >> 16) |
(second_dword << 16 & 0xff0000 ) |
(second_dword & 0xff000000);
/* unpack the limit */
limit = (first_dword & WORD_MASK) | (second_dword & 0xf0000);
if ( second_dword & BIT23_MASK )
{
/* Granularity Bit Set. Limit is expressed in pages
(4k bytes), convert to byte limit */
limit = limit << 12 | 0xfff;
}
descr->limit = limit;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Check for null selector */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL BOOL
selector_is_null
IFN1(
IU16, selector /* selector to be checked */
)
{
if ( GET_SELECTOR_INDEX(selector) == 0 && GET_SELECTOR_TI(selector) == 0 )
return TRUE;
return FALSE;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Check if selector outside bounds of GDT */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL BOOL
selector_outside_GDT
IFN2(
IU16, selector, /* (I) selector to be checked */
IU32 *, descr_addr /* (O) address of related descriptor */
)
{
IU16 offset;
offset = GET_SELECTOR_INDEX_TIMES8(selector);
/* make sure GDT then trap NULL selector or outside table */
if ( GET_SELECTOR_TI(selector) == 1 ||
offset == 0 || offset + 7 > GET_GDT_LIMIT() )
return TRUE;
*descr_addr = GET_GDT_BASE() + offset;
return FALSE;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Check if selector outside bounds of GDT or LDT */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL BOOL
selector_outside_GDT_LDT
IFN2(
IU16, selector, /* (I) selector to be checked */
IU32 *, descr_addr /* (O) address of related descriptor */
)
{
IU16 offset;
offset = GET_SELECTOR_INDEX_TIMES8(selector);
/* choose a table */
if ( GET_SELECTOR_TI(selector) == 0 )
{
/* GDT - trap NULL selector or outside table */
if ( offset == 0 || offset + 7 > GET_GDT_LIMIT() )
return TRUE;
*descr_addr = GET_GDT_BASE() + offset;
}
else
{
/* LDT - trap invalid LDT or outside table */
#ifndef DONT_CLEAR_LDTR_ON_INVALID
if ( GET_LDT_SELECTOR() <= 3 || offset + 7 > GET_LDT_LIMIT() )
#else
if ( GET_LDT_SELECTOR() == 0 || offset + 7 > GET_LDT_LIMIT() )
#endif /* DONT_CLEAR_LDTR_ON_INVALID */
return TRUE;
*descr_addr = GET_LDT_BASE() + offset;
}
return FALSE;
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Store new value in Intel EFLAGS register. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
c_setEFLAGS
IFN1(
IU32, flags
)
{
setFLAGS(flags); /* set lower word */
SET_RF((flags & BIT16_MASK) != 0);
if ( GET_CPL() == 0 )
SET_VM((flags & BIT17_MASK) != 0);
#ifdef SPC486
SET_AC((flags & BIT18_MASK) != 0);
#endif /* SPC486 */
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Store new value in Intel FLAGS register */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
setFLAGS
IFN1(
IU32, flags
)
{
SET_CF((flags & BIT0_MASK) != 0);
SET_PF((flags & BIT2_MASK) != 0);
SET_AF((flags & BIT4_MASK) != 0);
SET_ZF((flags & BIT6_MASK) != 0);
SET_SF((flags & BIT7_MASK) != 0);
SET_TF((flags & BIT8_MASK) != 0);
SET_DF((flags & BIT10_MASK) != 0);
SET_OF((flags & BIT11_MASK) != 0);
/* IF only updated if CPL <= IOPL */
if ( GET_CPL() <= GET_IOPL() )
SET_IF((flags & BIT9_MASK) != 0);
SET_NT((flags & BIT14_MASK) != 0);
/* IOPL only updated at highest privilege */
if ( GET_CPL() == 0 )
SET_IOPL((flags >> 12) & 3);
}
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