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379cd77078
On Windows, mmap() now chooses addresses transactionally. It reduces the risk of badness when interacting with the WIN32 memory manager. We don't throw darts anymore. There is also no more retry limit, since we recover from mystery maps more gracefully. The subroutine for combining adjacent maps has been rewritten for clarity. The print maps subroutine is better This change goes to great lengths to perfect the stack overflow code. On Windows you can now longjmp() out of a crash signal handler. Guard pages previously weren't being restored properly by the signal handler. That's fixed, so on Windows you can now handle a stack overflow multiple times. Great thought has been put into selecting the perfect SIGSTKSZ constants so you can save sigaltstack() memory. You can now use kprintf() with 512 bytes of stack available. The guard pages beneath the main stack are now recorded in the memory manager. This change fixes getcontext() so it works right with the %rax register.
54 lines
3 KiB
C
54 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 et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 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/sections.internal.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/thread/posixthread.internal.h"
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#include "libc/thread/tls.h"
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/**
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* Computes safer buffer size for alloca().
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*
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* @param want defines an upper limit on the return value
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* @param extraspace is how much stack caller needs that isn't buffer
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* @return number of bytes to use for your buffer, or negative if the
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* allocation would likely cause a stack overflow
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*/
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privileged optimizesize long __get_safe_size(long want, long extraspace) {
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if (!__tls_enabled)
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return want;
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struct PosixThread *pt;
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struct CosmoTib *tib = __get_tls_privileged();
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long bottom, sp = GetStackPointer();
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if (sp >= (long)tib->tib_sigstack_addr &&
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sp < (long)tib->tib_sigstack_addr + tib->tib_sigstack_size) {
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bottom = (long)tib->tib_sigstack_addr;
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} else if ((pt = (struct PosixThread *)tib->tib_pthread) &&
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sp >= (long)pt->pt_attr.__stackaddr &&
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sp < (long)pt->pt_attr.__stackaddr + pt->pt_attr.__stacksize) {
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bottom = (long)pt->pt_attr.__stackaddr;
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} else {
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return want;
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}
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long size = sp - bottom - extraspace;
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if (size > want)
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size = want;
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return size;
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}
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