60 lines
3.2 KiB
C
60 lines
3.2 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "ape/config.h"
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#include "ape/lib/pc.h"
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#include "libc/bits/bits.h"
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#include "libc/bits/safemacros.h"
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/**
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* Virtualizes physical memory.
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*
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* This function removes memory holes (discovered by e820() earlier) and
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* creates the illusion of flat contiguous memory for as much RAM as the
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* BIOS reports usable. Memory is safe to use and remap afterwards.
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*
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* @see ape/ape.S
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*/
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textreal void flattenhighmemory(struct SmapEntry *e820, struct PageTable *pml4t,
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uint64_t *ptsp) {
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struct SmapEntry *smap = e820;
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struct SmapEntry *hole = e820;
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uint64_t paddr = IMAGE_BASE_PHYSICAL;
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uint64_t vaddr = IMAGE_BASE_VIRTUAL;
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while (smap->size) {
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while (smap->size && smap->type != kMemoryUsable) smap++;
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paddr = roundup(max(paddr, smap->addr), PAGESIZE);
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while (paddr < rounddown(smap->addr + smap->size, PAGESIZE)) {
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while (hole->size &&
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(hole->type == kMemoryUsable || hole->addr + hole->size < paddr)) {
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hole++;
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}
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if (paddr >= hole->addr && paddr < hole->addr + hole->size) {
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paddr = roundup(hole->addr + hole->size, PAGESIZE);
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} else {
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uint64_t *entry = getpagetableentry(vaddr, 3, pml4t, ptsp);
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*entry = paddr | PAGE_V | PAGE_RW;
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vaddr += 0x1000;
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paddr += 0x1000;
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}
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}
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smap++;
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}
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}
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