736 lines
24 KiB
NASM
736 lines
24 KiB
NASM
title "Context Swap"
|
|
;++
|
|
;
|
|
; Copyright (c) 2000 Microsoft Corporation
|
|
;
|
|
; Module Name:
|
|
;
|
|
; ctxswap.asm
|
|
;
|
|
; Abstract:
|
|
;
|
|
; This module implements the code necessary to field the dispatch interrupt
|
|
; and perform context switching.
|
|
;
|
|
; Author:
|
|
;
|
|
; David N. Cutler (davec) 26-Aug-2000
|
|
;
|
|
; Environment:
|
|
;
|
|
; Kernel mode only.
|
|
;
|
|
;--
|
|
|
|
include ksamd64.inc
|
|
|
|
extern KeAcquireQueuedSpinLockAtDpcLevel:proc
|
|
extern KeAcquireQueuedSpinLockRaiseToSynch:proc
|
|
extern KeBugCheck:proc
|
|
extern KeReleaseQueuedSpinLock:proc
|
|
extern KeReleaseQueuedSpinLockFromDpcLevel:proc
|
|
extern KiDeliverApc:proc
|
|
extern KiDispatcherLock:qword
|
|
extern KiQuantumEnd:proc
|
|
extern KiReadyThread:proc
|
|
extern KiRetireDpcList:proc
|
|
extern __imp_HalRequestSoftwareInterrupt:qword
|
|
|
|
subttl "Unlock Dispatcher Database"
|
|
;++
|
|
;
|
|
; VOID
|
|
; KiUnlockDispatcherDatabase (
|
|
; IN KIRQL OldIrql
|
|
; )
|
|
;
|
|
; Routine Description:
|
|
;
|
|
; This routine is entered at SYNCH_LEVEL with the dispatcher database
|
|
; locked. Its function is to either unlock the dispatcher database and
|
|
; return or initiate a context switch if another thread has been selected
|
|
; for execution.
|
|
;
|
|
; Arguments:
|
|
;
|
|
; OldIrql (cl) - Supplies the IRQL when the dispatcher database lock was
|
|
; acquired.
|
|
;
|
|
; Return Value:
|
|
;
|
|
; None.
|
|
;
|
|
;--
|
|
|
|
UdFrame struct
|
|
P1Home dq ? ; queued spin lock number parameter
|
|
P2Home dq ? ; previous IRQL paramater
|
|
SavedIrql db ? ; saved previous IRQL
|
|
Fill db 7 dup (?) ; fill to 8 mod 16
|
|
UdFrame ends
|
|
|
|
NESTED_ENTRY KiUnlockDispatcherDatabase, _TEXT$00
|
|
|
|
alloc_stack (sizeof UdFrame) ; allocate stack frame
|
|
|
|
END_PROLOGUE
|
|
|
|
;
|
|
; Check if a new thread is scheduled for execution.
|
|
;
|
|
|
|
cmp qword ptr gs:[PcNextThread], 0 ; check if thread scheduled
|
|
jne short KiUD30 ; if ne, new thread scheduled
|
|
|
|
;
|
|
; Release dispatcher database lock, lower IRQL to its previous level,
|
|
; and return.
|
|
;
|
|
|
|
ifndef NT_UP
|
|
|
|
KiUD10: mov dl, cl ; set old IRQL value
|
|
mov ecx, LockQueueDispatcherLock ; set lock queue number
|
|
call KeReleaseQueuedSpinLock ; release dispatcher lock
|
|
|
|
else
|
|
|
|
KiUD10: movzx ecx, cl ; set IRQL to previous level
|
|
|
|
SetIrql ;
|
|
|
|
endif
|
|
|
|
add rsp, sizeof UdFrame ; deallocate stack frame
|
|
ret ; return
|
|
|
|
;
|
|
; A new thread has been selected to run on the current processor, but the new
|
|
; IRQL is not below dispatch level. If the current processor is not executing
|
|
; a DPC, then request a dispatch interrupt on the current processor.
|
|
;
|
|
|
|
KiUD20: cmp qword ptr gs:[PcDpcRoutineActive], 0 ; check if DPC routine active
|
|
jne short KiUD10 ; if ne, DPC routine is active
|
|
mov UdFrame.SavedIrql[rsp], cl ; save previous IRQL
|
|
mov cl, DISPATCH_LEVEL ; request dispatch interrupt
|
|
call __imp_HalRequestSoftwareInterrupt ;
|
|
mov cl, UdFrame.SavedIrql[rsp] ; restore previous IRQL
|
|
jmp short KiUD10
|
|
|
|
;
|
|
; Check if the previous IRQL is less than dispatch level.
|
|
;
|
|
|
|
KiUD30: cmp cl, DISPATCH_LEVEL ; check if IRQL below dispatch level
|
|
jge short KiUD20 ; if ge, not below dispatch level
|
|
add rsp, sizeof UdFrame ; deallocate stack frame
|
|
jmp short KxUnlockDispatcherDatabase ; finish in common code
|
|
|
|
NESTED_END KiUnlockDispatcherDatabase, _TEXT$00
|
|
|
|
;
|
|
; There is a new thread scheduled for execution and the previous IRQL is
|
|
; less than dispatch level. Context switch to the new thread immediately.
|
|
;
|
|
; N.B. The following routine is entered by falling through the from above
|
|
; code.
|
|
;
|
|
; N.B. The following routine is carefully written as a nested function that
|
|
; appears to have been called directly by the caller of the above
|
|
; function which unlocks the dispatcher database.
|
|
;
|
|
; Arguments:
|
|
;
|
|
; OldIrql (cl) - Supplies the IRQL when the dispatcher database lock was
|
|
; acquired.
|
|
;
|
|
|
|
NESTED_ENTRY KxUnlockDispatcherDatabase, _TEXT$00
|
|
|
|
GENERATE_EXCEPTION_FRAME ; generate exception frame
|
|
|
|
mov rbx, gs:[PcCurrentPrcb] ; get current PRCB address
|
|
mov rsi, PbNextThread[rbx] ; get next thread address
|
|
mov rdi, PbCurrentThread[rbx] ; get current thread address
|
|
and qword ptr PbNextThread[rbx], 0 ; clear next thread address
|
|
mov PbCurrentThread[rbx], rsi ; set current thread address
|
|
mov ThWaitIrql[rdi], cl ; save previous IRQL
|
|
|
|
ifndef NT_UP
|
|
|
|
mov byte ptr ThIdleSwapBlock[rdi], 1 ; block swap from idle
|
|
|
|
endif
|
|
|
|
mov rcx, rdi ; set address of current thread
|
|
call KiReadyThread ; reready thread for execution
|
|
xor eax, eax ; set NPX save false
|
|
mov cl, ThWaitIrql[rdi] ; set APC interrupt bypass disable
|
|
|
|
ifndef NT_UP
|
|
|
|
xor edx, edx ; set swap from idle false
|
|
|
|
endif
|
|
|
|
call SwapContext ; swap context
|
|
movzx ecx, byte ptr ThWaitIrql[rsi] ; get original wait IRQL
|
|
or al, al ; check if kernel APC pending
|
|
jz short KiXD10 ; if z, no kernel APC pending
|
|
mov ecx, APC_LEVEL ; set IRQL to APC level
|
|
|
|
SetIrql ;
|
|
|
|
xor ecx, ecx ; set previous mode to kernel
|
|
xor edx, edx ; clear exception frame address
|
|
xor r8, r8 ; clear trap frame address
|
|
call KiDeliverApc ; deliver kernel mode APC
|
|
xor ecx, ecx ; set original wait IRQL
|
|
KiXD10: ; reference label
|
|
|
|
SetIrql ; set IRQL to previous level
|
|
|
|
RESTORE_EXCEPTION_STATE ; restore exception state/deallocate
|
|
|
|
ret ; return
|
|
|
|
NESTED_END KxUnlockDispatcherDatabase, _TEXT$00
|
|
|
|
subttl "Swap Context"
|
|
;++
|
|
;
|
|
; BOOLEAN
|
|
; KiSwapContext (
|
|
; IN PKTHREAD Thread
|
|
; )
|
|
;
|
|
; Routine Description:
|
|
;
|
|
; This function is a small wrapper that marshalls arguments and calls the
|
|
; actual swap context routine.
|
|
;
|
|
; Arguments:
|
|
;
|
|
; Thread (rcx) - Supplies the address of the new thread.
|
|
;
|
|
; Return Value:
|
|
;
|
|
; If a kernel APC is pending, then a value of TRUE is returned. Otherwise,
|
|
; a value of FALSE is returned.
|
|
;
|
|
;--
|
|
|
|
NESTED_ENTRY KiSwapContext, _TEXT$00
|
|
|
|
GENERATE_EXCEPTION_FRAME ; generate exception frame
|
|
|
|
mov rbx, gs:[PcCurrentPrcb] ; get current PRCB address
|
|
mov rsi, rcx ; set next thread address
|
|
mov rdi, PbCurrentThread[rbx] ; get current thread address
|
|
mov PbCurrentThread[rbx], rsi ; set current thread address
|
|
xor eax, eax ; set NPX save false
|
|
mov cl, ThWaitIrql[rdi] ; set APC interrupt bypass disable
|
|
|
|
ifndef NT_UP
|
|
|
|
xor edx, edx ; set swap from idle false
|
|
|
|
endif
|
|
|
|
call SwapContext ; swap context
|
|
|
|
RESTORE_EXCEPTION_STATE ; restore exception state/deallocate
|
|
|
|
ret ; return
|
|
|
|
NESTED_END KiSwapContext, _TEXT$00
|
|
|
|
subttl "Dispatch Interrupt"
|
|
;++
|
|
;
|
|
; Routine Description:
|
|
;
|
|
; This routine is entered as the result of a software interrupt generated
|
|
; at DISPATCH_LEVEL. Its function is to process the DPC list, and then
|
|
; perform a context switch if a new thread has been selected for execution
|
|
; on the current processor.
|
|
;
|
|
; This routine is entered at DISPATCH_LEVEL with the dispatcher database
|
|
; unlocked.
|
|
;
|
|
; Arguments:
|
|
;
|
|
; None
|
|
;
|
|
; Return Value:
|
|
;
|
|
; None.
|
|
;
|
|
;--
|
|
|
|
DiFrame struct
|
|
P1Home dq ? ; PRCB address parameter
|
|
Fill dq ? ; fill to 8 mod 16
|
|
SavedRbx dq ? ; saved RBX
|
|
DiFrame ends
|
|
|
|
NESTED_ENTRY KiDispatchInterrupt, _TEXT$00
|
|
|
|
push_reg rbx ; save nonvolatile register
|
|
alloc_stack (sizeof DiFrame - 8) ; allocate stack frame
|
|
|
|
END_PROLOGUE
|
|
|
|
mov rbx, gs:[PcCurrentPrcb] ; get current PRCB address
|
|
and dword ptr PbDpcInterruptRequested[rbx], 0 ; clear request
|
|
|
|
;
|
|
; Check if the DPC queue has any entries to process.
|
|
;
|
|
|
|
KiDI10: cli ; disable interrupts
|
|
mov eax, PbDpcQueueDepth[rbx] ; get DPC queue depth
|
|
or eax, PbTimerHand[rbx] ; merge timer hand value
|
|
jz short KiDI20 ; if z, no DPCs to process
|
|
mov PbSavedRsp[rbx], rsp ; save current stack pointer
|
|
mov rsp, PbDpcStack[rbx] ; set DPC stack pointer
|
|
mov rcx, rbx ; set PRCB address parameter
|
|
call KiRetireDpcList ; process the DPC list
|
|
mov rsp, PbSavedRsp[rbx] ; restore current stack pointer
|
|
|
|
;
|
|
; Check to determine if quantum end is requested.
|
|
;
|
|
|
|
KiDI20: sti ; enable interrupts
|
|
cmp dword ptr PbQuantumEnd[rbx], 0 ; check if quantum end request
|
|
je short KiDI50 ; if e, quantum end not requested
|
|
|
|
;
|
|
; Process quantum end event.
|
|
;
|
|
; N.B. If a new thread is selected as a result of processing the quantum end
|
|
; request, then the new thread is returned with the dispatcher database
|
|
; locked. Otherwise, NULL is returned with the dispatcher database
|
|
; unlocked.
|
|
;
|
|
|
|
and dword ptr PbQuantumEnd[rbx], 0 ; clear quantum end indicator
|
|
call KiQuantumEnd ; process quantum end
|
|
test rax, rax ; test if new thread selected
|
|
jnz short KiDI60 ; if ne, new thread selected
|
|
|
|
;
|
|
; A new thread has not been selected for execution. Restore nonvolatile
|
|
; registers, deallocate stack frame, and return.
|
|
;
|
|
|
|
KiDI30: mov rbx, DiFrame.SavedRbx[rsp] ; restore nonvolatile register
|
|
add rsp, sizeof DiFrame ; deallocate stack frame
|
|
ret ; return
|
|
|
|
;
|
|
; The dispatch lock could not be acquired. Lower IRQL to dispatch level, and
|
|
; loop processing the DPC list and quantum end events.
|
|
;
|
|
|
|
KiDI40: mov ecx, DISPATCH_LEVEL ; set IRQL to DISPATCH_LEVEL
|
|
|
|
SetIrql ;
|
|
|
|
jmp short KiDI10 ; try again
|
|
|
|
;
|
|
; Check to determine if a new thread has been selected for execution on this
|
|
; processor.
|
|
;
|
|
|
|
KiDI50: cmp qword ptr PbNextThread[rbx], 0 ; check if new thread selected
|
|
je short KiDI30 ; if eq, then no new thread
|
|
|
|
ifndef NT_UP
|
|
|
|
mov ecx, SYNCH_LEVEL ; set IRQL to SYNCH_LEVEL
|
|
|
|
SetIrql ;
|
|
|
|
lea rcx, KiDispatcherLock ; get dispatcher database lock address
|
|
lea rdx, PbLockQueue + (16 * LockQueueDispatcherLock)[rbx] ; lock queue
|
|
xor eax, eax ; set comperand value to NULL
|
|
lock cmpxchg [rcx], rdx ; try to acquire dispatcher lock
|
|
jnz short KiDI40 ; if nz, dispatcher lock not acquired
|
|
|
|
endif
|
|
|
|
mov rax, PbNextThread[rbx] ; get next thread address
|
|
|
|
;
|
|
; Swap context to a new thread.
|
|
;
|
|
|
|
KiDI60: add rsp, sizeof DiFrame - 8 ; deallocate stack frame
|
|
pop rbx ; restore nonvolatile register
|
|
jmp short KxDispatchInterrupt ; finish in common code
|
|
|
|
NESTED_END KiDispatchInterrupt, _TEXT$00
|
|
|
|
;
|
|
; There is a new thread scheduled for execution and the dispatcher lock
|
|
; has been acquired. Context switch to the new thread immediately.
|
|
;
|
|
; N.B. The following routine is entered by falling through from the above
|
|
; routine.
|
|
;
|
|
; N.B. The following routine is carefully written as a nested function that
|
|
; appears to have been called directly by the caller of the above
|
|
; function which processes the dispatch interrupt.
|
|
;
|
|
; Arguments:
|
|
;
|
|
; Thread (rax) - Supplies the address of the next thread to run on the
|
|
; current processor.
|
|
;
|
|
|
|
NESTED_ENTRY KxDispatchInterrupt, _TEXT$00
|
|
|
|
GENERATE_EXCEPTION_FRAME ; generate exception frame
|
|
|
|
mov rbx, gs:[PcCurrentPrcb] ; get current PRCB address
|
|
mov rsi, rax ; set address of next thread
|
|
mov rdi, PbCurrentThread[rbx] ; get current thread address
|
|
and qword ptr PbNextThread[rbx], 0 ; clear next thread address
|
|
mov PbCurrentThread[rbx], rsi ; set current thread address
|
|
|
|
ifndef NT_UP
|
|
|
|
mov byte ptr ThIdleSwapBlock[rdi], 1 ; block swap from idle
|
|
|
|
endif
|
|
|
|
mov rcx, rdi ; set address of current thread
|
|
call KiReadyThread ; reready thread for execution
|
|
mov eax, TRUE ; set NPX save true
|
|
mov cl, APC_LEVEL ; set APC interrupt bypass disable
|
|
|
|
ifndef NT_UP
|
|
|
|
xor edx, edx ; set swap from idle false
|
|
|
|
endif
|
|
|
|
call SwapContext ; call context swap routine
|
|
|
|
RESTORE_EXCEPTION_STATE ; restore exception state/deallocate
|
|
|
|
ret ; return
|
|
|
|
NESTED_END KxDispatchInterrupt, _TEXT$00
|
|
|
|
subttl "Swap Context"
|
|
;++
|
|
;
|
|
; Routine Description:
|
|
;
|
|
; This routine is called to swap context from one thread to the next. It
|
|
; swaps context, flushes the translation buffer, swaps the process address
|
|
; space if necessary, and returns to its caller.
|
|
;
|
|
; N.B. This routine is only called by code within this module and the idle
|
|
; thread code and uses special register calling conventions.
|
|
;
|
|
; Arguments:
|
|
;
|
|
; al - Supplies a boolean value that determines whether the full legacy
|
|
; floating state needs to be saved.
|
|
;
|
|
; cl - Supplies the APC interrupt bypass disable IRQL value.
|
|
;
|
|
; edx - Supplies a logical value that specifies whether the context swap
|
|
; is being called from the idle thread (MP systems only).
|
|
;
|
|
; rbx - Supplies the address of the current PRCB.
|
|
;
|
|
; rdi - Supplies the address of previous thread.
|
|
;
|
|
; rsi - Supplies the address of next thread.
|
|
;
|
|
; Return value:
|
|
;
|
|
; al - Supplies the kernel APC pending flag.
|
|
;
|
|
; rbx - Supplies the address of the current PRCB.
|
|
;
|
|
; rsi - Supplies the address of current thread.
|
|
;
|
|
;--
|
|
|
|
NESTED_ENTRY SwapContext, _TEXT$00
|
|
|
|
push_reg rbp ; save nonvolatile register
|
|
alloc_stack (KSWITCH_FRAME_LENGTH - (2 * 8)) ; allocate stack frame
|
|
|
|
END_PROLOGUE
|
|
|
|
mov SwNpxSave[rsp], al ; save NPX save
|
|
mov SwApcBypass[rsp], cl ; save APC bypass disable
|
|
|
|
;
|
|
; Set the new thread state to running.
|
|
;
|
|
; N.B. The state of the new thread MUST be set to running before releasing
|
|
; the dispatcher lock.
|
|
;
|
|
|
|
mov byte ptr ThState[rsi], Running ; set thread state to running
|
|
|
|
;
|
|
; Acquire the context swap lock so the address space of the previous process
|
|
; cannot be deleted, then release the dispatcher database lock.
|
|
;
|
|
; N.B. The context swap lock is used to protect the address space until the
|
|
; context switch has sufficiently progressed to the point where the
|
|
; previous process address space is no longer needed. This lock is also
|
|
; acquired by the reaper thread before it finishes thread termination.
|
|
;
|
|
|
|
|
|
ifndef NT_UP
|
|
|
|
test edx, edx ; test if call from idle thread
|
|
jnz short KiSC05 ; if nz, call from idle thread
|
|
lea rcx, PbLockQueue + (16 * LockQueueContextSwapLock)[rbx] ; lock queue
|
|
call KeAcquireQueuedSpinLockAtDpcLevel ; acquire context swap lock
|
|
lea rcx, PbLockQueue + (16 * LockQueueDispatcherLock)[rbx] ; lock queue
|
|
call KeReleaseQueuedSpinLockFromDpcLevel ; release dispatcher lock
|
|
|
|
endif
|
|
|
|
;
|
|
; Check if an attempt is being made to context switch while in a DPC routine.
|
|
;
|
|
|
|
KiSC05: cmp dword ptr PbDpcRoutineActive[rbx], 0 ; check if DPC active
|
|
jne KiSC60 ; if ne, DPC is active
|
|
|
|
;
|
|
; Accumulate the total time spent in a thread.
|
|
;
|
|
|
|
ifdef PERF_DATA
|
|
|
|
rdtsc ; read cycle counter
|
|
sub eax, PbThreadStartCount + 0[rbx] ; sub out thread start time
|
|
sbb edx, PbThreadStartCount + 4[rbx] ;
|
|
add EtPerformanceCountLow[rdi], eax ; accumlate thread run time
|
|
adc EtPerformanceCountHigh[rdi], edx ;
|
|
add PbThreadStartCount + 4[rbx], eax ; set new thread start time
|
|
adc PbThreadStartCount + 8[rbx], edx ;
|
|
|
|
endif
|
|
|
|
;
|
|
; Save the kernel mode XMM control/status register. If the current thread
|
|
; executes in user mode, then also save the legacy floating point state.
|
|
;
|
|
|
|
stmxcsr SwMxCsr[rsp] ; save kernel mode XMM control/status
|
|
cmp byte ptr ThNpxState[rdi], UserMode ; check if user mode thread
|
|
jne short KiSC10 ; if ne, not user mode thread
|
|
mov rbp, ThInitialStack[rdi] ; get previous thread initial stack
|
|
cmp byte ptr SwNpxSave[rsp], TRUE ; check if full save required
|
|
jne short KiSC07 ; if ne, full save not required
|
|
fnsaved [rbp] ; save full legacy floating point state
|
|
jmp short KiSC10 ;
|
|
|
|
;
|
|
; Full floating save not required.
|
|
;
|
|
|
|
KiSC07: fnstenvd [rbp] ; save legacy floating environment
|
|
|
|
;
|
|
; Switch kernel stacks.
|
|
;
|
|
|
|
KiSC10: mov ThKernelStack[rdi], rsp ; save old kernel stack pointer
|
|
mov rsp, ThKernelStack[rsi] ; get new kernel stack pointer
|
|
|
|
;
|
|
; Swap the process address space if the new process is not the same as the
|
|
; previous process.
|
|
;
|
|
|
|
mov rax, ThApcState + AsProcess[rdi] ; get previous process address
|
|
cmp rax, ThApcState + AsProcess[rsi] ; check if process address match
|
|
je short KiSC20 ; if e, process addresses match
|
|
mov r14, ThApcState + AsProcess[rsi] ; get new process address
|
|
|
|
;
|
|
; Update the processor set masks.
|
|
;
|
|
|
|
ifndef NT_UP
|
|
|
|
mov rcx, PbSetMember[rbx] ; get processor set member
|
|
xor PrActiveProcessors[rax], rcx ; clear bit in previous set
|
|
xor PrActiveProcessors[r14], rcx ; set bit in new set
|
|
|
|
if DBG
|
|
|
|
test PrActiveProcessors[rax], rcx ; test if bit clear in previous set
|
|
jnz short @f ; if nz, bit not clear in previous set
|
|
test PrActiveProcessors[r14], rcx ; test if bit set in new set
|
|
jnz short KiSC15 ; if nz, bit set in new set
|
|
@@: int 3 ; debug break - incorrect active mask
|
|
|
|
endif
|
|
|
|
endif
|
|
|
|
;
|
|
; Load new CR3 value which will flush the TB and set the IOPM map offset in
|
|
; the TSS.
|
|
;
|
|
|
|
KiSC15: mov r15, gs:[PcTss] ; get processor TSS address
|
|
mov cx, PrIopmOffset[r14] ; get process IOPM offset
|
|
mov TssIoMapBase[r15], cx ; set TSS IOPM offset
|
|
mov rax, PrDirectoryTableBase[r14] ; get new directory base
|
|
mov cr3, rax ; flush TLB and set new directory base
|
|
|
|
;
|
|
; Release the context swap lock.
|
|
;
|
|
|
|
KiSC20: mov byte ptr ThIdleSwapBlock[rdi], 0 ; unblock swap from idle
|
|
|
|
ifndef NT_UP
|
|
|
|
lea rcx, PbLockQueue + (16 * LockQueueContextSwapLock)[rbx] ; lock queue
|
|
call KeReleaseQueuedSpinLockFromDpcLevel ; release context swap lock
|
|
|
|
endif
|
|
|
|
;
|
|
; Set the new kernel stack base in the TSS.
|
|
;
|
|
|
|
mov r15, gs:[PcTss] ; get processor TSS address
|
|
mov rbp, ThInitialStack[rsi] ; get new stack base address
|
|
mov TssRsp0[r15], rbp ; set stack base address in TSS
|
|
|
|
;
|
|
; If the new thread executes in user mode, then restore the legacy floating
|
|
; state, load the compatibility mode TEB address, load the native user mode
|
|
; TEB address, and reload the segment registers if needed.
|
|
;
|
|
; N.B. The upper 32-bits of the compatibility mode TEB address are always
|
|
; zero.
|
|
;
|
|
|
|
cmp byte ptr ThNpxState[rsi], UserMode ; check if user mode thread
|
|
jne KiSC30 ; if ne, not user mode thread
|
|
cmp byte ptr SwNpxSave[rsp], TRUE ; check if full restore required
|
|
jne short KiSC22 ; if ne, full restore not required
|
|
mov cx, LfControlWord[rbp] ; save current control word
|
|
mov word ptr LfControlWord[rbp], 03fh ; set to mask all exceptions
|
|
frstord [rbp] ; restore legacy floating point state
|
|
mov LfControlWord[rbp], cx ; restore control word
|
|
fldcw word ptr LfControlWord[rbp] ; load legacy control word
|
|
jmp short KiSC24 ;
|
|
|
|
;
|
|
; Full legacy floating restore not required.
|
|
;
|
|
|
|
KiSC22: fldenv [rbp] ; restore legacy floating environment
|
|
|
|
;
|
|
; Set base of compatibility mode TEB.
|
|
;
|
|
|
|
KiSC24: mov eax, ThTeb[rsi] ; compute compatibility mode TEB address
|
|
add eax, CmThreadEnvironmentBlockOffset ;
|
|
mov rcx, gs:[PcGdt] ; get GDT base address
|
|
mov KgdtBaseLow + KGDT64_R3_CMTEB[rcx], ax ; set CMTEB base address
|
|
shr eax, 16 ;
|
|
mov KgdtBaseMiddle + KGDT64_R3_CMTEB[rcx], al ;
|
|
mov KgdtBaseHigh + KGDT64_R3_CMTEB[rcx], ah ;
|
|
|
|
;
|
|
; If the user segment selectors have been changed, then reload them with
|
|
; their cannonical values.
|
|
;
|
|
|
|
mov ax, ds ; compute sum of segment selectors
|
|
mov cx, es ;
|
|
add ax, cx ;
|
|
mov cx, gs ;
|
|
add ax, cx ;
|
|
cmp ax, ((KGDT64_R3_DATA or RPL_MASK) * 3) ; check if sum matches
|
|
je short KiSC25 ; if e, sum matches expected value
|
|
mov cx, KGDT64_R3_DATA or RPL_MASK ; reload user segment selectors
|
|
mov ds, cx ;
|
|
mov es, cx ;
|
|
|
|
;
|
|
; N.B. The following reload of the GS selector destroys the system MSR_GS_BASE
|
|
; register. Thus this sequence must be done with interrupt off.
|
|
;
|
|
|
|
mov eax, gs:[PcSelf] ; get current PCR address
|
|
mov edx, gs:[PcSelf + 4] ;
|
|
cli ; disable interrupts
|
|
mov gs, cx ; reload GS segment selector
|
|
mov ecx, MSR_GS_BASE ; get GS base MSR number
|
|
wrmsr ; write system PCR base address
|
|
sti ; enable interrupts
|
|
KiSC25: mov ax, KGDT64_R3_CMTEB or RPL_MASK ; reload FS segment selector
|
|
mov fs, ax ;
|
|
mov eax, ThTeb[rsi] ; get low part of user TEB address
|
|
mov edx, ThTeb + 4[rsi] ; get high part of user TEB address
|
|
mov gs:[PcTeb], eax ; set user TEB address in PCR
|
|
mov gs:[PcTeb + 4], edx ;
|
|
mov ecx, MSR_GS_SWAP ; get GS base swap MSR number
|
|
wrmsr ; write user TEB base address
|
|
|
|
;
|
|
; Restore kernel mode XMM control/status and update context switch counters.
|
|
;
|
|
|
|
KiSC30: ldmxcsr SwMxCsr[rsp] ; kernel mode XMM control/status
|
|
inc dword ptr ThContextSwitches[rsi] ; thread count
|
|
inc dword ptr PbContextSwitches[rbx] ; processor count
|
|
|
|
;
|
|
; If the new thread has a kernel mode APC pending, then request an APC
|
|
; interrupt if APC bypass is disabled.
|
|
;
|
|
|
|
mov al, ThApcState + AsKernelApcPending[rsi] ; get APC pending
|
|
test al, al ; test if kernel APC pending
|
|
jz short KiSC50 ; if z, kernel APC not pending
|
|
cmp byte ptr SwApcBypass[rsp], APC_LEVEL ; check if APC bypass enabled
|
|
jb short KiSC40 ; if b, APC bypass is enabled
|
|
mov cl, APC_LEVEL ; request APC interrupt
|
|
call __imp_HalRequestSoftwareInterrupt ;
|
|
clc ; clear carry flag
|
|
KiSC40: setb al ; set return value
|
|
KiSC50: add rsp, KSWITCH_FRAME_LENGTH - (2 * 8) ; deallocate stack frame
|
|
pop rbp ; restore nonvolatile register
|
|
ret ; return
|
|
|
|
;
|
|
; An attempt is being made to context switch while in a DPC routine. This is
|
|
; most likely caused by a DPC routine calling one of the wait functions.
|
|
;
|
|
|
|
KiSC60: mov ecx, ATTEMPTED_SWITCH_FROM_DPC ; set bug check code
|
|
call KeBugCheck ; bug check system - no return
|
|
ret ; return
|
|
|
|
NESTED_END SwapContext, _TEXT$00
|
|
|
|
end
|