#------------------------------------------------------------------------------ # # Copyright (c) 2006 - 2009, Intel Corporation # All rights reserved. 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: # # DisablePaging64.S # # Abstract: # # AsmDisablePaging64 function # # Notes: # #------------------------------------------------------------------------------ #------------------------------------------------------------------------------ # VOID # EFIAPI # InternalX86DisablePaging64 ( # IN UINT16 Cs, # IN UINT32 EntryPoint, # IN UINT32 Context1, OPTIONAL # IN UINT32 Context2, OPTIONAL # IN UINT32 NewStack # ); #------------------------------------------------------------------------------ ASM_GLOBAL ASM_PFX(InternalX86DisablePaging64) ASM_PFX(InternalX86DisablePaging64): cli lea L1(%rip), %rsi # rsi <- The start address of transition code mov 0x28(%rsp), %edi # rdi <- New stack lea _mTransitionEnd(%rip), %rax # rax <- end of transition code sub %rsi, %rax # rax <- The size of transition piece code add $4, %rax # round rax up to the next 4 byte boundary and $0x0fffffffc, %rax sub %rax, %rdi # rdi <- use stack to hold transition code mov %edi, %r10d # r10 <- The start address of transicition code below 4G push %rcx # save rcx to stack mov %rax, %rcx # rcx <- The size of transition piece code rep movsb # copy transition code to (new stack - 64byte) below 4G pop %rcx # restore rcx mov %r8d, %esi mov %r9d, %edi mov %r10d, %eax sub $4, %eax push %rcx # push Cs to stack push %r10 # push address of transition code on stack .byte 0x48, 0xcb # retq: Use far return to load CS register from stack # (Use raw byte code since some GNU assemblers generates incorrect code for "retq") L1: mov %eax,%esp # set up new stack mov %cr0,%rax btr $0x1f,%eax # clear CR0.PG mov %rax,%cr0 # disable paging mov %edx,%ebx # save EntryPoint to ebx, for rdmsr will overwrite edx mov $0xc0000080,%ecx rdmsr and $0xfe,%ah # clear LME wrmsr mov %cr4,%rax and $0xdf,%al # clear PAE mov %rax,%cr4 push %rdi # push Context2 push %rsi # push Context1 callq *%rbx # transfer control to EntryPoint jmp . # no one should get here _mTransitionEnd :