358 lines
14 KiB
ArmAsm
358 lines
14 KiB
ArmAsm
// TITLE("Call Out to User Mode")
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// Copyright (c) 1994 Microsoft Corporation
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// Module Name:
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// callout.s
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// Abstract:
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// This module implements the code necessary to call out from kernel mode to user mode.
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// Author:
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// David N. Cutler (davec) 29-Oct-1994
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// Environment:
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// Kernel mode only.
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// Revision History:
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#include "ksmips.h"
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// Define external variables that can be addressed using GP.
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.extern KeUserCallbackDispatcher 4
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SBTTL("Call User Mode Function")
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// NTSTATUS KiCallUserMode (IN PVOID *OutputBuffer, IN PULONG OutputLength)
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// Routine Description:
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// This function calls a user mode function.
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// N.B. This function calls out to user mode and the NtCallbackReturn
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// function returns back to the caller of this function. Therefore, the stack layout must be consistent between the two routines.
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// Arguments:
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// OutputBuffer (a0) - Supplies a pointer to the variable that receivies the address of the output buffer.
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// OutputLength (a1) - Supplies a pointer to a variable that receives the length of the output buffer.
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// Return Value:
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// The final status of the call out function is returned as the status of the function.
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// N.B. This function does not return to its caller. A return to the
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// caller is executed when a NtCallbackReturn system service is executed.
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// N.B. This function does return to its caller if a kernel stack expansion is required and the attempted expansion fails.
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NESTED_ENTRY(KiCallUserMode, CuFrameLength, zero)
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subu sp,sp,CuFrameLength // allocate stack frame
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sw ra,CuRa(sp) // save return address
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// Save nonvolatile integer registers.
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sw s0,CuS0(sp) // save integer registers s0-s8
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sw s1,CuS1(sp) //
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sw s2,CuS2(sp) //
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sw s3,CuS3(sp) //
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sw s4,CuS4(sp) //
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sw s5,CuS5(sp) //
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sw s6,CuS6(sp) //
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sw s7,CuS7(sp) //
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sw s8,CuS8(sp) //
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// Save nonvolatile floating registers.
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sdc1 f20,CuF20(sp) // save floating registers f20-f31
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sdc1 f22,CuF22(sp) //
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sdc1 f24,CuF24(sp) //
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sdc1 f26,CuF26(sp) //
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sdc1 f28,CuF28(sp) //
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sdc1 f30,CuF30(sp) //
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PROLOGUE_END
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// Save argument registers.
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sw a0,CuA0(sp) // save output buffer address
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sw a1,CuA1(sp) // save output length address
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// Check if sufficient room is available on the kernel stack for another system call.
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lw t0,KiPcr + PcCurrentThread(zero) // get current thread address
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lw t1,KiPcr + PcInitialStack(zero) // get initial stack address
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lw t2,ThStackLimit(t0) // get current stack limit
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subu t3,sp,KERNEL_LARGE_STACK_COMMIT // compute bottom address
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sltu t4,t3,t2 // check if limit exceeded
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beq zero,t4,10f // if eq, limit not exceeded
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move a0,sp // set current kernel stack address
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jal MmGrowKernelStack // attempt to grow the kernel stack
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lw t0,KiPcr + PcCurrentThread(zero) // get current thread address
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lw t1,KiPcr + PcInitialStack(zero) // get initial stack address
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lw t2,ThStackLimit(t0) // get expanded stack limit
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bne zero,v0,20f // if ne, attempt to grow failed
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sw t2,KiPcr + PcStackLimit(zero) // set expanded stack limit
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// Get the address of the current thread and save the previous trap frame
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// and callback stack addresses in the current frame. Also save the new
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// callback stack address in the thread object.
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10: lw s8,ThTrapFrame(t0) // get trap frame address
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lw t2,ThCallbackStack(t0) // get callback stack address
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sw t1,CuInStk(sp) // save initial stack address
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sw s8,CuTrFr(sp) // save trap frame address
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sw t2,CuCbStk(sp) // save callback stack address
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sw sp,ThCallbackStack(t0) // set callback stack address
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// Restore state and callback to user mode.
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lw t2,TrFsr(s8) // get previous floating status
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li t3,CU1_ENABLE // set coprocessor 1 enable bits
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.set noreorder
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.set noat
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cfc1 t4,fsr // get current floating status
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mtc0 t3,psr // disable interrupts - 3 cycle hazzard
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ctc1 t2,fsr // restore previous floating status
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lw t3,TrPsr(s8) // get previous processor status
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sw sp,ThInitialStack(t0) // reset initial stack address
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sw sp,KiPcr + PcInitialStack(zero) //
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sw t4,CuFsr(sp) // save current floating status
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lw t4,KeUserCallbackDispatcher // set continuation address
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// If a user mode APC is pending, then request an APC interrupt.
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lbu t1,ThApcState + AsUserApcPending(t0) // get user APC pending
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sb zero,ThAlerted(t0) // clear kernel mode alerted
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mfc0 t2,cause // get exception cause register
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sll t1,t1,(APC_LEVEL + CAUSE_INTPEND - 1) // shift APC pending
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or t2,t2,t1 // merge possilbe APC interrupt request
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mtc0 t2,cause // set exception cause register
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// Save the new processor status and continuation PC in the PCR so a TB
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// miss is not possible, then restore the volatile register state.
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sw t3,KiPcr + PcSavedT7(zero) // save processor status
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j KiServiceExit // join common code
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sw t4,KiPcr + PcSavedEpc(zero) // save continuation address
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.set at
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.set reorder
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// An attempt to grow the kernel stack failed.
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20: lw ra,CuRa(sp) // restore return address
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addu sp,sp,CuFrameLength // deallocate stack frame
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j ra // return
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.end KiCalluserMode
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SBTTL("Switch Kernel Stack")
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// PVOID KeSwitchKernelStack (IN PVOID StackBase, IN PVOID StackLimit)
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// Routine Description:
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// This function switches to the specified large kernel stack.
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// N.B. This function can ONLY be called when there are no variables
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// in the stack that refer to other variables in the stack, i.e., there are no pointers into the stack.
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// Arguments:
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// StackBase (a0) - Supplies a pointer to the base of the new kernel stack.
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// StackLimit (a1) - supplies a pointer to the limit of the new kernel stack.
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// Return Value:
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// The old kernel stack is returned as the function value.
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.struct 0
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.space 4 * 4 // argument register save area
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SsRa: .space 4 // saved return address
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SsSp: .space 4 // saved new stack pointer
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.space 2 * 4 // fill
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SsFrameLength: // length of stack frame
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SsA0: .space 4 // saved argument registers a0-a1
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SsA1: .space 4 //
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NESTED_ENTRY(KeSwitchKernelStack, SsFrameLength, zero)
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subu sp,sp,SsFrameLength // allocate stack frame
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sw ra,SsRa(sp) // save return address
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PROLOGUE_END
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// Save the address of the new stack and copy the old stack to the new
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// stack.
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lw t0,KiPcr + PcCurrentThread(zero) // get current thread address
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sw a0,SsA0(sp) // save new kernel stack base address
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sw a1,SsA1(sp) // save new kernel stack limit address
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lw a2,ThStackBase(t0) // get current stack base address
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lw a3,ThTrapFrame(t0) // get current trap frame address
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addu a3,a3,a0 // relocate current trap frame address
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subu a3,a3,a2 //
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sw a3,ThTrapFrame(t0) //
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move a1,sp // set source address of copy
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subu a2,a2,sp // compute length of copy
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subu a0,a0,a2 // set destination address of copy
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sw a0,SsSp(sp) // save new stack pointer address
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jal RtlMoveMemory // copy old stack to new stack
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// Switch to new kernel stack and return the address of the old kernel
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// stack.
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lw t0,KiPcr + PcCurrentThread(zero) // get current thread address
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DISABLE_INTERRUPTS(t1) // disable interrupts
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lw v0,ThStackBase(t0) // get old kernel stack base address
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lw a0,SsA0(sp) // get new kernel stack base address
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lw a1,SsA1(sp) // get new kernel stack limit address
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sw a0,ThInitialStack(t0) // set new initial stack address
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sw a0,ThStackBase(t0) // set new stack base address
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sw a1,ThStackLimit(t0) // set new stack limit address
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li v1,TRUE // set large kernel stack TRUE
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sb v1,ThLargeStack(t0) //
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sw a0,KiPcr + PcInitialStack(zero) // set initial stack adddress
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sw a1,KiPcr + PcStackLimit(zero) // set stack limit
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lw sp,SsSp(sp) // switch to new kernel stack
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ENABLE_INTERRUPTS(t1) // enable interrupts
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lw ra,SsRa(sp) // restore return address
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addu sp,sp,SsFrameLength // deallocate stack frame
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j ra // return
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.end KeSwitchKernelStack
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SBTTL("Return from User Mode Callback")
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// NTSTATUS
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// NtCallbackReturn (
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// IN PVOID OutputBuffer OPTIONAL,
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// IN ULONG OutputLength,
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// IN NTSTATUS Status
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// )
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// Routine Description:
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// This function returns from a user mode callout to the kernel
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// mode caller of the user mode callback function.
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// N.B. This function returns to the function that called out to user
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// mode and the KiCallUserMode function calls out to user mode.
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// Therefore, the stack layout must be consistent between the
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// two routines.
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// Arguments:
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// OutputBuffer - Supplies an optional pointer to an output buffer.
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// OutputLength - Supplies the length of the output buffer.
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// Status - Supplies the status value returned to the caller of the
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// callback function.
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// Return Value:
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// If the callback return cannot be executed, then an error status is
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// returned. Otherwise, the specified callback status is returned to
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// the caller of the callback function.
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// N.B. This function returns to the function that called out to user
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// mode is a callout is currently active.
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LEAF_ENTRY(NtCallbackReturn)
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lw t0,KiPcr + PcCurrentThread(zero) // get current thread address
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lw t1,ThCallbackStack(t0) // get callback stack address
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beq zero,t1,10f // if eq, no callback stack present
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// Restore nonvolatile integer registers.
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lw s0,CuS0(t1) // restore integer registers s0-s8
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lw s1,CuS1(t1) //
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lw s2,CuS2(t1) //
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lw s3,CuS3(t1) //
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lw s4,CuS4(t1) //
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lw s5,CuS5(t1) //
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lw s6,CuS6(t1) //
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lw s7,CuS7(t1) //
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lw s8,CuS8(t1) //
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// Save nonvolatile floating registers.
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ldc1 f20,CuF20(t1) // restore floating registers f20-f31
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ldc1 f22,CuF22(t1) //
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ldc1 f24,CuF24(t1) //
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ldc1 f26,CuF26(t1) //
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ldc1 f28,CuF28(t1) //
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ldc1 f30,CuF30(t1) //
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// Restore the trap frame and callback stacks addresses, store the output
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// buffer address and length, restore the floating status, and set the
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// service status.
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lw t2,CuTrFr(t1) // get previous trap frame address
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lw t3,CuCbStk(t1) // get previous callback stack address
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lw t4,CuA0(t1) // get address to store output address
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lw t5,CuA1(t1) // get address to store output length
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lw t6,CuFsr(t1) // get previous floating status
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sw t2,ThTrapFrame(t0) // restore trap frame address
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sw t3,ThCallbackStack(t0) // restore callback stack address
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sw a0,0(t4) // store output buffer address
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sw a1,0(t5) // store output buffer length
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.set noreorder
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.set noat
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ctc1 t6,fsr // restore previous floating status
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.set at
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.set reorder
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move v0,a2 // set callback service status
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// Restore initial stack pointer, trim stackback to callback frame,
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// deallocate callback stack frame, and return to callback caller.
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lw t2,CuInStk(t1) // get previous initial stack
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DISABLE_INTERRUPTS(t3) // disable interrupts
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sw t2,ThInitialStack(t0) // restore initial stack address
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sw t2,KiPcr + PcInitialStack(zero) //
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move sp,t1 // trim stack back callback frame
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ENABLE_INTERRUPTS(t3) // enable interrupts
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lw ra,CuRa(sp) // restore return address
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addu sp,sp,CuFrameLength // deallocate stack frame
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j ra // return
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// No callback is currently active.
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10: li v0,STATUS_NO_CALLBACK_ACTIVE // set service status
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j ra // return
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.end NtCallbackReturn
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