_vflat.asm

AT91RM9200-U-Boot at91rm9200u-boot移植源代码

cprocstart  InstallBankFunc

        ARG     codeLen:UINT, bankFunc:DPTR

        enter_c

        mov     esi,[bankFunc]      ; Copy the code into buffer
        mov     edi,offset BankFuncBuf
        mov     ecx,[codeLen]
    rep movsb
        mov     [BYTE edi],0C3h     ; Terminate the function with a near ret

        leave_c
        ret

cprocend

;----------------------------------------------------------------------------
; int InitPaging(void)
;----------------------------------------------------------------------------
; Initializes paging system. If paging is not enabled, builds a page table
; directory and page tables for physical memory
;
;   Exit:       0   - Successful
;               -1  - Couldn't initialize paging mechanism
;----------------------------------------------------------------------------
cprocstart  InitPaging

        push    ebx
        push    ecx
        push    edx
        push    esi
        push    edi

; Are we running under CauseWay?

        mov     ax,0FFF9h
        int     31h
        jc      @@NotCauseway
        cmp     ecx,"CAUS"
        jnz     @@NotCauseway
        cmp     edx,"EWAY"
        jnz     @@NotCauseway

        mov     [BOOL VF_haveCauseWay],1
        mov     [CauseWayDIRLinear],esi
        mov     [CauseWay1stLinear],edi

; Check for DPMI

        mov     ax,0ff00h
        push    es
        int     31h
        pop     es
        shr     edi,2
        and     edi,3
        cmp     edi,2
        jz      @@ErrExit               ; Not supported under DPMI

        mov     eax,[CauseWayDIRLinear]
        jmp     @@CopyCR3

@@NotCauseway:
        mov     ax,cs
        test    ax,3                    ; Which ring are we running
        jnz     @@ErrExit               ; Needs zero ring to access
                                        ; page tables (CR3)
        mov     eax,cr0                 ; Load CR0
        test    eax,80000000h           ; Is paging enabled?
        jz      @@ErrExit               ; No, we must have paging!

        mov     eax,cr3                 ; Load directory address
        and     eax,0FFFFF000h

@@CopyCR3:
        mov     [PDBR],eax              ; Save it
        mov     esi,eax
        mov     edi,offset pageDirectory
        mov     ecx,1024
        cld
        rep     movsd                   ; Copy the original page table directory
        cmp     [DWORD accessPageAddr],0; Check if we have allocated page
        jne     @@HaveRealMem           ; table already (we cant free it)

        mov     eax,0100h               ; DPMI DOS allocate
        mov     ebx,8192/16
        int     31h                     ; Allocate 8192 bytes
        and     eax,0FFFFh
        shl     eax,4                   ; EAX points to newly allocated memory
        add     eax,4095
        and     eax,0FFFFF000h          ; Page align
        mov     [accessPageAddr],eax

@@HaveRealMem:
        mov     eax,[accessPageAddr]    ; EAX -> page table in 1st Mb
        shr     eax,12
        and     eax,3FFh                ; Page table offset
        shl     eax,2
        cmp     [BOOL VF_haveCauseWay],0
        jz      @@NotCW0
        mov     ebx,[CauseWay1stLinear]
        jmp     @@Put1st

@@NotCW0:
        mov     ebx,[PDBR]
        mov     ebx,[ebx]
        and     ebx,0FFFFF000h          ; Page table for 1st megabyte

@@Put1st:
        add     eax,ebx
        mov     [accessPageTable],eax
        sub     eax,eax                 ; No error
        jmp     @@Exit

@@ErrExit:
        mov     eax,-1

@@Exit: pop     edi
        pop     esi
        pop     edx
        pop     ecx
        pop     ebx
        ret

cprocend

;----------------------------------------------------------------------------
; void ClosePaging(void)
;----------------------------------------------------------------------------
; Closes the paging system
;----------------------------------------------------------------------------
cprocstart  ClosePaging

        push    eax
        push    ecx
        push    edx
        push    esi
        push    edi

        mov     eax,[accessPageAddr]
        call    AccessPage              ; Restore AccessPage mapping
        mov     edi,[PDBR]
        mov     esi,offset pageDirectory
        mov     ecx,1024
        cld
        rep     movsd                   ; Restore the original page table directory

@@Exit: pop     edi
        pop     esi
        pop     edx
        pop     ecx
        pop     eax
        ret

cprocend

;----------------------------------------------------------------------------
; long AccessPage(long phys)
;----------------------------------------------------------------------------
; Maps a known page to given physical memory
;   Entry:      EAX - Physical memory
;   Exit:       EAX - Linear memory address of mapped phys mem
;----------------------------------------------------------------------------
cprocstatic     AccessPage

        push    edx
        mov     edx,[accessPageTable]
        or      eax,7
        mov     [edx],eax
        mov     eax,cr3
        mov     cr3,eax                 ; Update page table cache
        mov     eax,[accessPageAddr]
        pop     edx
        ret

cprocend

;----------------------------------------------------------------------------
; long GetPhysicalAddress(long linear)
;----------------------------------------------------------------------------
; Returns the physical address of linear address
;   Entry:      EAX - Linear address to convert
;   Exit:       EAX - Physical address
;----------------------------------------------------------------------------
cprocstatic     GetPhysicalAddress

        push    ebx
        push    edx
        mov     edx,eax
        shr     edx,22                  ; EDX is the directory offset
        mov     ebx,[PDBR]
        mov     edx,[edx*4+ebx]         ; Load page table address
        push    eax
        mov     eax,edx
        call    AccessPage              ; Access the page table
        mov     edx,eax
        pop     eax
        shr     eax,12
        and     eax,03FFh               ; EAX offset into page table
        mov     eax,[edx+eax*4]         ; Load physical address
        and     eax,0FFFFF000h
        pop     edx
        pop     ebx
        ret

cprocend

;----------------------------------------------------------------------------
; void CreatePageTable(long pageDEntry)
;----------------------------------------------------------------------------
; Creates a page table for specific address (4MB)
;       Entry:  EAX - Page directory entry (top 10-bits of address)
;----------------------------------------------------------------------------
cprocstatic     CreatePageTable

        push    ebx
        push    ecx
        push    edx
        push    edi
        mov     ebx,eax                 ; Save address
        mov     eax,8192
        push    eax
        call    VF_malloc              ; Allocate page table directory
        add     esp,4
        add     eax,0FFFh
        and     eax,0FFFFF000h          ; Page align (4KB)
        mov     edi,eax                 ; Save page table linear address
        sub     eax,eax                 ; Fill with zero
        mov     ecx,1024
        cld
        rep     stosd                   ; Clear page table
        sub     edi,4096
        mov     eax,edi
        call    GetPhysicalAddress
        mov     edx,[PDBR]
        or      eax,7                   ; Present/write/user bit
        mov     [edx+ebx*4],eax         ; Save physical address into page directory
        mov     eax,cr3
        mov     cr3,eax                 ; Update page table cache
        pop     edi
        pop     edx
        pop     ecx
        pop     ebx
        ret

cprocend

;----------------------------------------------------------------------------
; void MapPhysical2Linear(ulong pAddr, ulong lAddr, int pages, int flags);
;----------------------------------------------------------------------------
; Maps physical memory into linear memory
;   Entry:      pAddr   - Physical address
;               lAddr   - Linear address
;               pages   - Number of 4K pages to map
;               flags   - Page flags
;                           bit 0   =       present
;                           bit 1   =       Read(0)/Write(1)
;----------------------------------------------------------------------------
cprocstart  MapPhysical2Linear

        ARG     pAddr:ULONG, lAddr:ULONG, pages:UINT, pflags:UINT

        enter_c

        and     [ULONG pAddr],0FFFFF000h; Page boundary
        and     [ULONG lAddr],0FFFFF000h; Page boundary
        mov     ecx,[pflags]
        and     ecx,11b                 ; Just two bits
        or      ecx,100b                ; Supervisor bit
        mov     [pflags],ecx

        mov     edx,[lAddr]
        shr     edx,22                  ; EDX = Directory
        mov     esi,[PDBR]
        mov     edi,[pages]             ; EDI page count
        mov     ebx,[lAddr]

@@CreateLoop:
        mov     ecx,[esi+edx*4]         ; Load page table address
        test    ecx,1                   ; Is it present?
        jnz     @@TableOK
        mov     eax,edx
        call    CreatePageTable         ; Create a page table
@@TableOK:
        mov     eax,ebx
        shr     eax,12
        and     eax,3FFh
        sub     eax,1024
        neg     eax                     ; EAX = page count in this table
        inc     edx                     ; Next table
        mov     ebx,0                   ; Next time we'll map 1K pages
        sub     edi,eax                 ; Subtract mapped pages from page count
        jns     @@CreateLoop            ; Create more tables if necessary

        mov     ecx,[pages]             ; ECX = Page count
        mov     esi,[lAddr]
        shr     esi,12                  ; Offset part isn't needed
        mov     edi,[pAddr]
@@MappingLoop:
        mov     eax,esi
        shr     eax,10                  ; EAX = offset to page directory
        mov     ebx,[PDBR]
        mov     eax,[eax*4+ebx]         ; EAX = page table address
        call    AccessPage
        mov     ebx,esi
        and     ebx,3FFh                ; EBX = offset to page table
        mov     edx,edi
        add     edi,4096                ; Next physical address
        inc     esi                     ; Next linear page
        or      edx,[pflags]            ; Update flags...
        mov     [eax+ebx*4],edx         ; Store page table entry
        loop    @@MappingLoop
        mov     eax,cr3
        mov     cr3,eax                 ; Update page table cache

        leave_c
        ret

cprocend

endcodeseg  _vflat

endif

        END                     ; End of module