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[WIP] Get bare metal working outside of an emulator (#609)

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You can now run bare metal on bare metal!

* Fix handling of int 0x15 eax = 0xe820 memory map
* Fix some issues in initial page table creation
* hello4.com now works outside emulators
* Ensure area for identity page tables are zeroed first
* Simplify logic for creating page table entries, this partly
  reverts 577c0f6226
* Add degenerate MBR partition entry, to ease testing

Co-authored-by: tkchia <tkchia-cosmo@gmx.com>
This commit is contained in:
tkchia 2022-09-13 17:01:49 +08:00 • committed by Justine Tunney
parent c03359c637
commit 116bda997e
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GPG key ID: BE714B4575D6E328
3 changed files with 55 additions and 35 deletions
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5
libc/intrin/mman.greg.c
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@ -74,6 +74,7 @@ noasan textreal uint64_t *__get_virtual(struct mman *mm, uint64_t *t,
if (!(*e & PAGE_V)) {
if (!maketables) return NULL;
if (!(p = __new_page(mm))) return NULL;
__clear_page(BANE + p);
*e = p | PAGE_V | PAGE_RW;
}
t = (uint64_t *)(BANE + (*e & PAGE_TA));
@ -117,7 +118,7 @@ static noasan textreal void __invert_memory(struct mman *mm, uint64_t *pml4t) {
uint64_t i, j, *m, p, pe;
for (i = 0; i < mm->e820n; ++i) {
for (p = mm->e820[i].addr, pe = mm->e820[i].addr + mm->e820[i].size;
p + 0x200000 < pe; p += 4096) {
p != pe + 0x200000; p += 4096) {
m = __get_virtual(mm, pml4t, BANE + p, true);
if (m && !(*m & PAGE_V)) {
*m = p | PAGE_V | PAGE_RW;
@ -150,7 +151,7 @@ noasan textreal void __map_phdrs(struct mman *mm, uint64_t *pml4t, uint64_t b) {
v = b + p->p_offset + i;
m = MAX(m, v);
} else {
v = __clear_page(__new_page(mm));
v = __clear_page(BANE + __new_page(mm));
}
*__get_virtual(mm, pml4t, p->p_vaddr + i, true) = (v & PAGE_TA) | f;
}