;------------------------------------------------------------------------------ ;
; Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
; This program and the accompanying materials
; are licensed and made available under the terms and conditions of the BSD License
; which accompanies this distribution.  The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php.
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;
; Module Name:
;
;   MpFuncs.nasm
;
; Abstract:
;
;   This is the assembly code for MP support
;
;-------------------------------------------------------------------------------

%include "MpEqu.inc"
extern ASM_PFX(InitializeFloatingPointUnits)

SECTION .text

;-------------------------------------------------------------------------------------
;RendezvousFunnelProc  procedure follows. All APs execute their procedure. This
;procedure serializes all the AP processors through an Init sequence. It must be
;noted that APs arrive here very raw...ie: real mode, no stack.
;ALSO THIS PROCEDURE IS EXECUTED BY APs ONLY ON 16 BIT MODE. HENCE THIS PROC
;IS IN MACHINE CODE.
;-------------------------------------------------------------------------------------
global ASM_PFX(RendezvousFunnelProc)
ASM_PFX(RendezvousFunnelProc):
RendezvousFunnelProcStart:
; At this point CS = 0x(vv00) and ip= 0x0.
BITS 16
    mov        ebp, eax                        ; save BIST information

    mov        ax, cs
    mov        ds, ax
    mov        es, ax
    mov        ss, ax
    xor        ax, ax
    mov        fs, ax
    mov        gs, ax

    mov        si,  BufferStartLocation
    mov        ebx, [si]

    mov        si,  ModeOffsetLocation
    mov        eax, [si]
    mov        si,  CodeSegmentLocation
    mov        edx, [si]
    mov        di,  ax
    sub        di,  02h
    mov        [di], dx
    sub        di,  04h
    add        eax, ebx
    mov        [di],eax

    mov        si,  DataSegmentLocation
    mov        edx, [si]

    mov        si, GdtrLocation
o32 lgdt       [cs:si]

    mov        si, IdtrLocation
o32 lidt       [cs:si]

    xor        ax,  ax
    mov        ds,  ax

    mov        eax, cr0                        ;Get control register 0
    or         eax, 000000003h                 ;Set PE bit (bit #0) & MP
    mov        cr0, eax

    jmp        0:strict dword 0                ; far jump to protected mode
BITS 32
Flat32Start:                                   ; protected mode entry point
    mov        ds, dx
    mov        es, dx
    mov        fs, dx
    mov        gs, dx
    mov        ss, dx

    mov        esi, ebx
    mov        edi, esi
    add        edi, LockLocation
    mov        eax, NotVacantFlag

TestLock:
    xchg       [edi], eax
    cmp        eax, NotVacantFlag
    jz         TestLock

    mov        edi, esi
    add        edi, NumApsExecutingLoction
    inc        dword [edi]
    mov        ebx, [edi]

ProgramStack:
    mov        edi, esi
    add        edi, StackSizeLocation
    mov        eax, [edi]
    mov        edi, esi
    add        edi, StackStartAddressLocation
    add        eax, [edi]
    mov        esp, eax
    mov        [edi], eax

Releaselock:
    mov        eax, VacantFlag
    mov        edi, esi
    add        edi, LockLocation
    xchg       [edi], eax

CProcedureInvoke:
    push       ebp               ; push BIST data at top of AP stack
    xor        ebp, ebp          ; clear ebp for call stack trace
    push       ebp
    mov        ebp, esp

    mov        eax, ASM_PFX(InitializeFloatingPointUnits)
    call       eax               ; Call assembly function to initialize FPU per UEFI spec

    push       ebx               ; Push NumApsExecuting
    mov        eax, esi
    add        eax, LockLocation
    push       eax               ; push address of exchange info data buffer

    mov        edi, esi
    add        edi, ApProcedureLocation
    mov        eax, [edi]

    call       eax               ; invoke C function

    jmp        $                 ; never reach here
RendezvousFunnelProcEnd:

;-------------------------------------------------------------------------------------
;  AsmGetAddressMap (&AddressMap);
;-------------------------------------------------------------------------------------
global ASM_PFX(AsmGetAddressMap)
ASM_PFX(AsmGetAddressMap):
    pushad
    mov        ebp,esp

    mov        ebx,  [ebp + 24h]
    mov        dword [ebx], RendezvousFunnelProcStart
    mov        dword [ebx +  4h], Flat32Start - RendezvousFunnelProcStart
    mov        dword [ebx +  8h], RendezvousFunnelProcEnd - RendezvousFunnelProcStart

    popad
    ret

;-------------------------------------------------------------------------------------
;AsmExchangeRole procedure follows. This procedure executed by current BSP, that is
;about to become an AP. It switches it'stack with the current AP.
;AsmExchangeRole (IN   CPU_EXCHANGE_INFO    *MyInfo, IN   CPU_EXCHANGE_INFO    *OthersInfo);
;-------------------------------------------------------------------------------------
global ASM_PFX(AsmExchangeRole)
ASM_PFX(AsmExchangeRole):
    ; DO NOT call other functions in this function, since 2 CPU may use 1 stack
    ; at the same time. If 1 CPU try to call a function, stack will be corrupted.
    pushad
    mov        ebp,esp

    ; esi contains MyInfo pointer
    mov        esi, [ebp + 24h]

    ; edi contains OthersInfo pointer
    mov        edi, [ebp + 28h]

    ;Store EFLAGS, GDTR and IDTR register to stack
    pushfd
    mov        eax, cr4
    push       eax       ; push cr4 firstly
    mov        eax, cr0
    push       eax

    sgdt       [esi + 8]
    sidt       [esi + 14]

    ; Store the its StackPointer
    mov        [esi + 4],esp

    ; update its switch state to STORED
    mov        byte [esi], CPU_SWITCH_STATE_STORED

WaitForOtherStored:
    ; wait until the other CPU finish storing its state
    cmp        byte [edi], CPU_SWITCH_STATE_STORED
    jz         OtherStored
    pause
    jmp        WaitForOtherStored

OtherStored:
    ; Since another CPU already stored its state, load them
    ; load GDTR value
    lgdt       [edi + 8]

    ; load IDTR value
    lidt       [edi + 14]

    ; load its future StackPointer
    mov        esp, [edi + 4]

    ; update the other CPU's switch state to LOADED
    mov        byte [edi], CPU_SWITCH_STATE_LOADED

WaitForOtherLoaded:
    ; wait until the other CPU finish loading new state,
    ; otherwise the data in stack may corrupt
    cmp        byte [esi], CPU_SWITCH_STATE_LOADED
    jz         OtherLoaded
    pause
    jmp        WaitForOtherLoaded

OtherLoaded:
    ; since the other CPU already get the data it want, leave this procedure
    pop        eax
    mov        cr0, eax
    pop        eax
    mov        cr4, eax
    popfd

    popad
    ret
