projects / mirror_edk2.git / blame
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|---|---|---|
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1 | ;------------------------------------------------------------------------------\r |
| 2 | ;\r | |
| 3 | ; Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>\r | |
| 4 | ; This program and the accompanying materials\r | |
| 5 | ; are licensed and made available under the terms and conditions of the BSD License\r | |
| 6 | ; which accompanies this distribution. The full text of the license may be found at\r | |
| 7 | ; http://opensource.org/licenses/bsd-license.php.\r | |
| 8 | ;\r | |
| 9 | ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
| 10 | ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
| 11 | ;\r | |
| 12 | ; Module Name:\r | |
| 13 | ;\r | |
| 14 | ; DisablePaging64.Asm\r | |
| 15 | ;\r | |
| 16 | ; Abstract:\r | |
| 17 | ;\r | |
| 18 | ; AsmDisablePaging64 function\r | |
| 19 | ;\r | |
| 20 | ; Notes:\r | |
| 21 | ;\r | |
| 22 | ;------------------------------------------------------------------------------\r | |
| 23 | \r | |
| 24 | DEFAULT REL\r | |
| 25 | SECTION .text\r | |
| 26 | \r | |
| 27 | ;------------------------------------------------------------------------------\r | |
| 28 | ; VOID\r | |
| 29 | ; EFIAPI\r | |
| 30 | ; InternalX86DisablePaging64 (\r | |
| 31 | ; IN UINT16 Cs,\r | |
| 32 | ; IN UINT32 EntryPoint,\r | |
| 33 | ; IN UINT32 Context1, OPTIONAL\r | |
| 34 | ; IN UINT32 Context2, OPTIONAL\r | |
| 35 | ; IN UINT32 NewStack\r | |
| 36 | ; );\r | |
| 37 | ;------------------------------------------------------------------------------\r | |
| 38 | global ASM_PFX(InternalX86DisablePaging64)\r | |
| 39 | ASM_PFX(InternalX86DisablePaging64):\r | |
| 40 | cli\r | |
| 41 | lea rsi, [.0] ; rsi <- The start address of transition code\r | |
| 42 | mov edi, [rsp + 0x28] ; rdi <- New stack\r | |
| 43 | lea rax, [mTransitionEnd] ; rax <- end of transition code\r | |
| 44 | sub rax, rsi ; rax <- The size of transition piece code\r | |
| 45 | add rax, 4 ; Round RAX up to the next 4 byte boundary\r | |
| 46 | and al, 0xfc\r | |
| 47 | sub rdi, rax ; rdi <- Use stack to hold transition code\r | |
| 48 | mov r10d, edi ; r10 <- The start address of transicition code below 4G\r | |
| 49 | push rcx ; save rcx to stack\r | |
| 50 | mov rcx, rax ; rcx <- The size of transition piece code\r | |
| 51 | rep movsb ; copy transition code to top of new stack which must be below 4GB\r | |
| 52 | pop rcx ; restore rcx\r | |
| 53 | \r | |
| 54 | mov esi, r8d\r | |
| 55 | mov edi, r9d\r | |
| 56 | mov eax, r10d ; eax <- start of the transition code on the stack\r | |
| 57 | sub eax, 4 ; eax <- One slot below transition code on the stack\r | |
| 58 | push rcx ; push Cs to stack\r | |
| 59 | push r10 ; push address of tansition code on stack\r | |
| 60 | DB 0x48 ; prefix to composite "retq" with next "retf"\r | |
| 61 | retf ; Use far return to load CS register from stack\r | |
| 62 | \r | |
| 63 | ; Start of transition code\r | |
| 64 | .0:\r | |
| 65 | mov esp, eax ; set up new stack\r | |
| 66 | mov rax, cr0\r | |
| 67 | btr eax, 31 ; Clear CR0.PG\r | |
| 68 | mov cr0, rax ; disable paging and caches\r | |
| 69 | \r | |
| 70 | mov ebx, edx ; save EntryPoint to rbx, for rdmsr will overwrite rdx\r | |
| 71 | mov ecx, 0xc0000080\r | |
| 72 | rdmsr\r | |
| 73 | and ah, ~ 1 ; clear LME\r | |
| 74 | wrmsr\r | |
| 75 | mov rax, cr4\r | |
| 76 | and al, ~ (1 << 5) ; clear PAE\r | |
| 77 | mov cr4, rax\r | |
| 78 | push rdi ; push Context2\r | |
| 79 | push rsi ; push Context1\r | |
| 80 | call rbx ; transfer control to EntryPoint\r | |
| 81 | hlt ; no one should get here\r | |
| 82 | \r | |
| 83 | mTransitionEnd:\r | |
| 84 | \r |