mirror of
https://github.com/jart/cosmopolitan.git
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63 lines
3 KiB
C
63 lines
3 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 2022 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 "libc/calls/calls.h"
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#include "libc/dce.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/intrin/asancodes.h"
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#include "libc/runtime/memtrack.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/stack.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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/**
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* Allocates stack.
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*
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* The size of your returned stack is always GetStackSize().
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*
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* The bottom 4096 bytes of your stack can't be used, since it's always
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* reserved for a read-only guard page. With ASAN it'll be poisoned too.
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*
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* The top 16 bytes of a stack can't be used due to openbsd:stackbound
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* and those bytes are also poisoned under ASAN build modes.
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*
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* @return stack bottom address on success, or null w/ errno
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*/
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void *_mapstack(void) {
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char *p;
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if ((p = mmap(0, GetStackSize(), PROT_READ | PROT_WRITE,
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MAP_STACK | MAP_ANONYMOUS, -1, 0)) != MAP_FAILED) {
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if (IsAsan()) {
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__asan_poison(p + GetStackSize() - 16, 16, kAsanStackOverflow);
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__asan_poison(p, 4096, kAsanStackOverflow);
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}
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return p;
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} else {
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return 0;
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}
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}
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/**
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* Frees stack.
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*
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* @param stk was allocated by _mapstack()
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*/
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int _freestack(void *stk) {
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return munmap(stk, GetStackSize());
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}
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