OVMF VTF0 Reset Vector: Cleanup Global Descriptor Table (GDT)

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9676 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
jljusten 2010-01-04 16:18:09 +00:00
parent d22d1f535b
commit 141815f3c7
7 changed files with 57 additions and 64 deletions

View File

@ -63,78 +63,71 @@ gdtr:
ALIGN 16
;
; Macros for GDT entries
;
%define PRESENT_FLAG(p) (p << 7)
%define DPL(dpl) (dpl << 5)
%define SYSTEM_FLAG(s) (s << 4)
%define DESC_TYPE(t) (t)
; Type: data, expand-up, writable, accessed
%define DATA32_TYPE 3
; Type: execute, readable, expand-up, accessed
%define CODE32_TYPE 0xb
; Type: execute, readable, expand-up, accessed
%define CODE64_TYPE 0xb
%define GRANULARITY_FLAG(g) (g << 7)
%define DEFAULT_SIZE32(d) (d << 6)
%define CODE64_FLAG(l) (l << 5)
%define UPPER_LIMIT(l) (l)
;
; The Global Descriptor Table (GDT)
;
GDT_BASE:
; null descriptor
NULL_SEL equ $-GDT_BASE
dw 0 ; limit 15:0
dw 0 ; base 15:0
db 0 ; base 23:16
db 0 ; type
db 0 ; limit 19:16, flags
db 0 ; base 31:24
DW 0 ; limit 15:0
DW 0 ; base 15:0
DB 0 ; base 23:16
DB 0 ; sys flag, dpl, type
DB 0 ; limit 19:16, flags
DB 0 ; base 31:24
; linear data segment descriptor
LINEAR_SEL equ $-GDT_BASE
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 093h ; present, ring 0, data, expand-up, writable, accessed
db 0CFh ; page-granular, 32-bit
db 0
LINEAR_SEL equ $-GDT_BASE
DW 0xffff ; limit 15:0
DW 0 ; base 15:0
DB 0 ; base 23:16
DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(DATA32_TYPE)
DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf)
DB 0 ; base 31:24
; linear code segment descriptor
LINEAR_CODE_SEL equ $-GDT_BASE
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Bh ; present, ring 0, data, expand-up, writable, accessed
db 0CFh ; page-granular, 32-bit
db 0
LINEAR_CODE_SEL equ $-GDT_BASE
DW 0xffff ; limit 15:0
DW 0 ; base 15:0
DB 0 ; base 23:16
DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE32_TYPE)
DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf)
DB 0 ; base 31:24
; system data segment descriptor
SYS_DATA_SEL equ $-GDT_BASE
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 093h ; present, ring 0, data, expand-up, writable, accessed
db 0CFh ; page-granular, 32-bit
db 0
; system code segment descriptor
SYS_CODE_SEL equ $-GDT_BASE
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Bh ; present, ring 0, data, expand-up, writable, accessed
db 0CFh ; page-granular, 32-bit
db 0
; spare segment descriptor
LINEAR_CODE64_SEL equ $-GDT_BASE
DW -1 ; LimitLow
DW 0 ; BaseLow
DB 0 ; BaseMid
DB 9bh
DB 0afh ; LimitHigh (CS.L=1, CS.D=0)
DB 0 ; BaseHigh
; spare segment descriptor
SPARE4_SEL equ $-GDT_BASE
dw 0 ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 0 ; present, ring 0, data, expand-up, writable
db 0 ; page-granular, 32-bit
db 0
; spare segment descriptor
SPARE5_SEL equ $-GDT_BASE
dw 0 ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 0 ; present, ring 0, data, expand-up, writable
db 0 ; page-granular, 32-bit
db 0
%ifdef ARCH_X64
; linear code (64-bit) segment descriptor
LINEAR_CODE64_SEL equ $-GDT_BASE
DW 0xffff ; limit 15:0
DW 0 ; base 15:0
DB 0 ; base 23:16
DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE64_TYPE)
DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(0)|CODE64_FLAG(1)|UPPER_LIMIT(0xf)
DB 0 ; base 31:24
%endif
GDT_END: