43 lines
2.5 KiB
C
43 lines
2.5 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/lib/pc.h"
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#include "libc/assert.h"
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static textreal uint64_t __pushpagetable(uint64_t *ptsp) {
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return (*ptsp -= PAGESIZE) | PAGE_V | PAGE_RW;
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}
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textreal uint64_t *__getpagetableentry(int64_t vaddr, unsigned depth,
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struct PageTable *pml4t,
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uint64_t *ptsp) {
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uint64_t *entry;
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unsigned char shift;
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assert(depth <= 3);
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assert(!(*ptsp & 0xfff));
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assert(!((uintptr_t)pml4t & 0xfff));
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shift = 39;
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for (;;) {
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entry = &pml4t->p[(vaddr >> shift) & 511];
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if (!depth--) return entry;
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shift -= 9;
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if (!*entry) *entry = __pushpagetable(ptsp);
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pml4t = (void *)(*entry & PAGE_TA);
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}
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}
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