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UefiCpuPkg/MpInitLib: split wake up buffer into two parts

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If PcdDxeNxMemoryProtectionPolicy is set to enable protection for memory
of EfiBootServicesCode, EfiConventionalMemory, the BIOS will hang at a page
fault exception during MP initialization.

The root cause is that the AP wake up buffer, which is below 1MB and used
to hold both AP init code and data, is type of EfiConventionalMemory (not
really allocated because of potential conflict with legacy code), and is
marked as non-executable. During the transition from real address mode
to long mode, the AP init code has to enable paging which will then cause
itself a page fault exception because it's just running in non-executable
memory.

The solution is splitting AP wake up buffer into two part: lower part is
still below 1MB and shared with legacy system, higher part is really
allocated memory of BootServicesCode type. The init code in the memory
below 1MB will not enable paging but just switch to protected mode and
jump to higher memory, in which the init code will enable paging and
switch to long mode.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
This commit is contained in:
Jian J Wang
2017-12-29 09:12:54 +08:00
committed by Ruiyu Ni
parent 4f10654e04
commit f32bfe6d06
8 changed files with 204 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
UefiCpuPkg/Library/MpInitLib/Ia32/MpFuncs.nasm
View File

@@ -48,34 +48,35 @@ BITS 16
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]
;
; Get start address of 32-bit code in low memory (<1MB)
;
mov edi, ModeTransitionMemoryLocation
mov si, GdtrLocation
o32 lgdt [cs:si]
mov si, IdtrLocation
o32 lidt [cs:si]
xor ax, ax
mov ds, ax
;
; Switch to protected mode
;
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
; Switch to 32-bit code in executable memory (>1MB)
o32 jmp far [cs:di]
;
; Following code may be copied to memory with type of EfiBootServicesCode.
; This is required at DXE phase if NX is enabled for EfiBootServicesCode of
; memory.
;
BITS 32
Flat32Start: ; protected mode entry point
mov ds, dx
@@ -266,6 +267,7 @@ ASM_PFX(AsmGetAddressMap):
mov dword [ebx + 8h], RendezvousFunnelProcEnd - RendezvousFunnelProcStart
mov dword [ebx + 0Ch], AsmRelocateApLoopStart
mov dword [ebx + 10h], AsmRelocateApLoopEnd - AsmRelocateApLoopStart
mov dword [ebx + 14h], Flat32Start - RendezvousFunnelProcStart
popad
ret