sravan/system76-edk2
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix the bug in x64 thunk code that it cannot handle the case when GDT is loaded in above 4G table memory.

Browse Source 
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@8390 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
qhuang8
2009-05-26 11:41:12 +00:00
parent 57ee276f16
commit a148780114
2 changed files with 37 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
MdePkg/Library/BaseLib/X64/Thunk16.S
View File

@@ -264,7 +264,23 @@ ASM_PFX(InternalAsmThunk16):
shll $12,%eax # segment address in high order 16 bits
lea (_BackFromUserCode - ASM_PFX(m16Start))(%rdx), %ax
stosl # [edi] <- return address of user code
sgdt (SavedGdt - SavedCr4)(%rcx)
sgdt 0x60(%rsp) # save GDT stack in argument space
movzwq 0x60(%rsp), %r10 # r10 <- GDT limit
lea ((ASM_PFX(InternalAsmThunk16) - SavedCr4) + 0xf)(%rcx), %r11
andl $0xfffffff0, r11 # r11 <- 16-byte aligned shadowed GDT table in real mode buffer
movw %r10w, (SavedGdt - SavedCr4)(%rcx) # save the limit of shadowed GDT table
movq %r11, (SavedGdt - SavedCr4 + 0x2)(%rcx) # save the base address of shadowed GDT table
movq 0x62(%rsp) ,%rsi # rsi <- the original GDT base address
xchg %r10, %rcx # save rcx to r10 and initialize rcx to be the limit of GDT table
incq %rcx # rcx <- the size of memory to copy
xchg %r11, %rdi # save rdi to r11 and initialize rdi to the base address of shadowed GDT table
rep
movsb # perform memory copy to shadow GDT table
movq %r10, %rcx # restore the orignal rcx before memory copy
movq %r11, %rdi # restore the original rdi before memory copy
sidt 0x50(%rsp)
movq %cr0, %rax
movl %eax, (SavedCr0 - SavedCr4)(%rcx)
@@ -288,7 +304,8 @@ ASM_PFX(InternalAsmThunk16):
.byte _EntryPoint - SavedCr4
L_RetFromRealMode:
popfq
lidt 0x50(%rsp)
lgdt 0x60(%rsp) # restore protected mode GDTR
lidt 0x50(%rsp) # restore protected mode IDTR
lea -IA32_REGS_SIZE(%rbp), %eax
.byte 0x0f, 0xa9 # pop gs
.byte 0x0f, 0xa1 # pop fs