56 lines
3.1 KiB
C
56 lines
3.1 KiB
C
/*-*- 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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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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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/macros.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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uint64_t *entry, paddr, vaddr;
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struct SmapEntry *smap, *hole;
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for (smap = hole = e820, vaddr = IMAGE_BASE_VIRTUAL; smap->size; ++smap) {
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while (smap->size && smap->type != kMemoryUsable) smap++;
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paddr = ROUNDUP(MAX(IMAGE_BASE_PHYSICAL, 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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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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}
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}
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