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Bare metal: ensure area for identity page tables is zeroed first

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This commit is contained in:
tkchia 2022-09-11 21:55:44 +00:00
parent 577c0f6226
commit d94c373484
1 changed files with 11 additions and 3 deletions
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14
ape/ape.S
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@ -1392,9 +1392,16 @@ a20: cli
// Initializes long mode paging.
pinit: push %ds
push %es
#define SEG 0x79000
mov $SEG>>4,%ax
mov %ax,%ds
mov %ax,%es
xor %di,%di
xor %ax,%ax
mov $(0x7f000-SEG)/2,%cx
cld
rep stosw
movl $0x7d000+PAGE_V+PAGE_RW,0x7e000-SEG # PDPT←PML4T (+)
movl $0x7c000+PAGE_V+PAGE_RW,0x7e800-SEG # PDPT←PML4T (-)
movl $0x7b000+PAGE_V+PAGE_RW,0x7d000-SEG # PDT←PDPT (+)
@ -1403,13 +1410,14 @@ pinit: push %ds
movl $0x79000+PAGE_V+PAGE_RW,0x7a000-SEG # PD←PDT (-)
mov $512,%cx # PD±2MB
mov $PAGE_V+PAGE_RW,%eax
xor %si,%si
0: mov %eax,(%si)
xor %di,%di
0: stosl
add $0x1000,%eax
add $8,%si
scasl # di += 4
loop 0b
mov $0x7e000,%eax # PML4T←CR3
mov %eax,%cr3
pop %es
pop %ds
ret
.endfn pinit