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cosmopolitan/libc/runtime/mremap.c
Justine Tunney 226aaf3547 Improve memory safety 
This commit makes numerous refinements to cosmopolitan memory handling.

The default stack size has been reduced from 2mb to 128kb. A new macro
is now provided so you can easily reconfigure the stack size to be any
value you want. Work around the breaking change by adding to your main:

    STATIC_STACK_SIZE(0x00200000);  // 2mb stack

If you're not sure how much stack you need, then you can use:

    STATIC_YOINK("stack_usage_logging");

After which you can `sort -nr o/$MODE/stack.log`. Based on the unit test
suite, nothing in the Cosmopolitan repository (except for Python) needs
a stack size greater than 30kb. There are also new macros for detecting
the size and address of the stack at runtime, e.g. GetStackAddr(). We
also now support sigaltstack() so if you want to see nice looking crash
reports whenever a stack overflow happens, you can put this in main():

    ShowCrashReports();

Under `make MODE=dbg` and `make MODE=asan` the unit testing framework
will now automatically print backtraces of memory allocations when
things like memory leaks happen. Bugs are now fixed in ASAN global
variable overrun detection. The memtrack and asan runtimes also handle
edge cases now. The new tools helped to identify a few memory leaks,
which are fixed by this change.

This change should fix an issue reported in #288 with ARG_MAX limits.
Fixing this doubled the performance of MKDEPS.COM and AR.COM yet again.
2021-10-13 17:27:13 -07:00

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/likely.h"
#include "libc/bits/weaken.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/sysdebug.internal.h"
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/log/libfatal.internal.h"
#include "libc/macros.internal.h"
#include "libc/nt/runtime.h"
#include "libc/runtime/directmap.internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/mremap.h"
#include "libc/sysv/errfuns.h"
#define IP(X) (intptr_t)(X)
#define VIP(X) (void *)IP(X)
#define SMALL(n) ((n) <= 0xffffffffffff)
#define ALIGNED(p) (!(IP(p) & (FRAMESIZE - 1)))
#define LEGAL(p) (-0x800000000000 <= IP(p) && IP(p) <= 0x7fffffffffff)
#define ADDR(x) ((int64_t)((uint64_t)(x) << 32) >> 16)
#define SHADE(x) (((intptr_t)(x) >> 3) + 0x7fff8000)
#define FRAME(x) ((int)((intptr_t)(x) >> 16))
static size_t GetMapSize(size_t i, size_t *j) {
size_t n;
n = (size_t)(_mmi.p[i].y - _mmi.p[i].x + 1) << 16;
while (i + 1 < _mmi.i) {
if (_mmi.p[i + 1].x != _mmi.p[i].y + 1) break;
++i;
n += (size_t)(_mmi.p[i].y - _mmi.p[i].x + 1) << 16;
}
*j = i;
return n;
}
static bool MustMoveMap(intptr_t y, size_t j) {
return ADDR(_mmi.p[j].y) + FRAMESIZE > y ||
(j + 1 < _mmi.i && ADDR(_mmi.p[j + 1].x) < y);
}
/**
* Extends and/or relocates memory pages.
*
* @param p is old address
* @param n is old size
* @param m is new size
* @param f should have MREMAP_MAYMOVE and may have MAP_FIXED
* @param q is new address
*/
void *mremap(void *p, size_t n, size_t m, int f, ... /* void *q */) {
enosys();
return MAP_FAILED;
void *q;
va_list va;
size_t i, j, k;
struct DirectMap dm;
int a, b, prot, flags;
if (UNLIKELY(!m)) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EINVAL (m=0)", p, n, m, f);
return VIP(einval());
}
if (UNLIKELY(!n)) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EOPNOTSUPP (n=0)", p, n, m, f);
return VIP(eopnotsupp());
}
if (UNLIKELY(!ALIGNED(n))) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EOPNOTSUPP (n align)", p, n, m, f);
return VIP(eopnotsupp());
}
if (UNLIKELY(!ALIGNED(m))) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EOPNOTSUPP (n align)", p, n, m, f);
return VIP(eopnotsupp());
}
if (UNLIKELY(!ALIGNED(p))) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EINVAL (64kb align)", p, n, m, f);
return VIP(einval());
}
if (UNLIKELY(!SMALL(n))) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EINVAL (n too big)", p, n, m, f);
return VIP(enomem());
}
if (UNLIKELY(!SMALL(m))) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EINVAL (m too big)", p, n, m, f);
return VIP(enomem());
}
if (f & ~(MREMAP_MAYMOVE | MREMAP_FIXED)) {
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x) EINVAL (bad flag)", p, n, m, f);
return VIP(einval());
}
if (!IsMemtracked(FRAME(p), FRAME((intptr_t)p + (n - 1)))) {
SYSDEBUG("munmap(0x%x, 0x%x) EFAULT (interval not tracked)", p, n);
return VIP(efault());
}
SYSDEBUG("mremap(0x%p, 0x%x, 0x%x, 0x%x)", p, n, m, f);
i = FindMemoryInterval(&_mmi, FRAME(p));
if (i >= _mmi.i) return VIP(efault());
flags = _mmi.p[i].flags;
if (!(flags & MAP_ANONYMOUS)) {
return VIP(eopnotsupp()); /* TODO */
}
if (f & MREMAP_FIXED) {
va_start(va, f);
q = va_arg(va, void *);
va_end(va);
if (!ALIGNED(q)) return VIP(einval());
return VIP(eopnotsupp()); /* TODO */
}
prot = _mmi.p[i].prot;
for (k = i + 1; k <= j; ++k) {
prot |= _mmi.p[k].prot;
if (_mmi.p[k].flags != flags) {
return VIP(enomem());
}
}
if (m == n) {
return p;
} else if (m < n) {
if (munmap((char *)p + n, m - n) != -1) {
return p;
} else {
return MAP_FAILED;
}
} else if (!MustMoveMap(j, (intptr_t)p + n)) {
dm = sys_mmap((char *)p + n, m - n, prot, flags | MAP_FIXED, -1, 0);
if (dm.addr == MAP_FAILED) return 0;
if (TrackMemoryInterval(&_mmi, ((uintptr_t)p + n) >> 16,
((uintptr_t)p + m - FRAMESIZE) >> 16, dm.maphandle,
prot, flags) != -1) {
if (weaken(__asan_map_shadow)) {
weaken(__asan_map_shadow)((uintptr_t)dm.addr, m - n);
}
return p;
} else {
abort();
}
} else if (!(f & MREMAP_MAYMOVE)) {
return VIP(enomem());
} else if (IsLinux()) {
a = (uint32_t)(kAutomapStart >> 16);
i = FindMemoryInterval(&_mmi, a);
if (i < _mmi.i) {
for (; i + 1 < _mmi.i; ++i) {
if (((size_t)(_mmi.p[i + 1].x - _mmi.p[i].y - 1) << 16) >= m) {
break;
}
}
if (__builtin_add_overflow(_mmi.p[i].y, 1, &a)) {
return VIP(enomem());
}
}
if (__builtin_add_overflow(a, (int)((m >> 16) - 1), &b)) {
return VIP(enomem());
}
q = sys_mremap((void *)p, n, m, MREMAP_MAYMOVE | MREMAP_FIXED,
(void *)ADDR(a));
SYSDEBUG("sys_mremap(0x%p, 0x%x, 0x%x, 0x%x, 0x%x) -> 0x%p", p, n, m,
MREMAP_MAYMOVE | MREMAP_FIXED, ADDR(a));
if (q == MAP_FAILED) return 0;
if (ReleaseMemoryIntervals(&_mmi, (uintptr_t)p >> 16,
((uintptr_t)p + n - FRAMESIZE) >> 16, 0) != -1 &&
TrackMemoryInterval(&_mmi, a, b, -1, prot, flags) != -1) {
if (weaken(__asan_poison)) {
if (!OverlapsShadowSpace(p, n)) {
weaken(__asan_poison)((intptr_t)p, n, kAsanUnmapped);
}
if (!OverlapsShadowSpace(q, m)) {
weaken(__asan_map_shadow)((intptr_t)q, m);
}
}
return (void *)ADDR(a);
} else {
abort();
}
} else if ((q = mmap(0, m, prot, flags, -1, 0)) != MAP_FAILED) {
memcpy(q, p, n);
munmap(p, n);
return q;
} else {
return q;
}
}
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