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Preserve GDT across prot_call().

This commit is contained in:
Michael Brown 2006-05-06 18:52:27 +00:00
parent dcc1b0054e
commit c10d1aa9d7
1 changed files with 12 additions and 6 deletions
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18
src/arch/i386/transitions/librm.S
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@ -335,7 +335,8 @@ rm_ds: .word 0
****************************************************************************
*/
#define PC_OFFSET_IX86 ( 0 )
#define PC_OFFSET_GDT ( 0 )
#define PC_OFFSET_IX86 ( PC_OFFSET_GDT + 8 /* pad to 8 to keep alignment */ )
#define PC_OFFSET_RETADDR ( PC_OFFSET_IX86 + SIZEOF_I386_ALL_REGS )
#define PC_OFFSET_FUNCTION ( PC_OFFSET_RETADDR + 4 )
#define PC_OFFSET_END ( PC_OFFSET_FUNCTION + 4 )
@ -344,7 +345,7 @@ rm_ds: .word 0
.code16
.globl prot_call
prot_call:
/* Preserve registers and flags on external RM stack */
/* Preserve registers, flags and GDT on external RM stack */
pushfl
pushal
pushw %gs
@ -353,6 +354,9 @@ prot_call:
pushw %ds
pushw %ss
pushw %cs
subw $8, %sp
movw %sp, %bp
sgdt (%bp)
/* For sanity's sake, clear the direction flag as soon as possible */
cld
@ -368,7 +372,8 @@ prot_call:
call gateA20_set
/* Call function */
pushl %esp
leal PC_OFFSET_IX86(%esp), %eax
pushl %eax
call *(PC_OFFSET_FUNCTION+4)(%esp)
popl %eax /* discard */
@ -379,9 +384,10 @@ prot_call:
.section ".text16"
.code16
1:
/* Restore registers and flags and return */
popw %ax /* skip %cs - it is already set */
popw %ax /* skip %ss - it is already set */
/* Reload GDT, restore registers and flags and return */
movw %sp, %bp
lgdt (%bp)
addw $12, %sp /* also skip %cs and %ss */
popw %ds
popw %es
popw %fs