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Fixed the stack switching.

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It isn't possible to access memory between changing the stack and setting the cr3 register. 
A page fault needs a valid kmode stack which is possible not available.

svn path=/trunk/; revision=15129
This commit is contained in:
Hartmut Birr 2005-05-08 15:59:07 +00:00
parent f4ce8b5664
commit 6e529ef561
1 changed files with 13 additions and 12 deletions
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25
reactos/ntoskrnl/ke/i386/ctxswitch.S
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@ -152,26 +152,27 @@ SaveTrapFrameForKDB_Return:
/* Save the stack pointer in this processors TSS */
mov ebp, [ebx+KPCR_TSS]
push ss:[ebp+KTSS_ESP0]
/* Check if address space switch is needed */
mov eax, [esi+KTHREAD_APCSTATE_PROCESS]
cmp eax, [edi+KTHREAD_APCSTATE_PROCESS]
mov eax, [eax+KPROCESS_DIRECTORY_TABLE_BASE]
/* Switch stacks */
mov [edi+KTHREAD_KERNEL_STACK], esp
mov esp, [esi+KTHREAD_KERNEL_STACK]
/*
* Sadly, ROS memory management is screwed up, so
* we must change the address space here.
*/
mov eax, [esi+KTHREAD_APCSTATE_PROCESS]
mov eax, [eax+KPROCESS_DIRECTORY_TABLE_BASE]
mov cr3, eax
jz NoAddressSpaceSwitch
/* Switch address space */
mov cr3, eax
NoAddressSpaceSwitch:
/* Stack is OK, safe to enable interrupts now */
sti
/* Check if address space switch is needed */
mov eax, [edi+KTHREAD_APCSTATE_PROCESS]
cmp eax, [esi+KTHREAD_APCSTATE_PROCESS]
/* Check if address space switch is needed (the result from above is valid) */
/* If they match, then use the fast-path and skip all this */
jz SameProcess