cosmopolitan/libc/runtime/munmap.c
Justine Tunney 6f7d0cb1c3
Pay off more technical debt
This makes breaking changes to add underscores to many non-standard
function names provided by the c library. MODE=tiny is now tinier and
we now use smaller locks that are better for tiny apps in this mode.
Some headers have been renamed to be in the same folder as the build
package, so it'll be easier to know which build dependency is needed.
Certain old misguided interfaces have been removed. Intel intrinsics
headers are now listed in libc/isystem (but not in the amalgamation)
to help further improve open source compatibility. Header complexity
has also been reduced. Lastly, more shell scripts are now available.
2022-09-12 23:36:56 -07:00

172 lines
6.2 KiB
C

/*-*- 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/calls/state.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/likely.h"
#include "libc/intrin/strace.internal.h"
#include "libc/log/backtrace.internal.h"
#include "libc/log/libfatal.internal.h"
#include "libc/log/log.h"
#include "libc/macros.internal.h"
#include "libc/runtime/directmap.internal.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"
#define IP(X) (intptr_t)(X)
#define ALIGNED(p) (!(IP(p) & (FRAMESIZE - 1)))
#define ADDR(x) ((int64_t)((uint64_t)(x) << 32) >> 16)
#define FRAME(x) ((int)((intptr_t)(x) >> 16))
static noasan int Munmap(char *, size_t);
static noasan void MunmapShadow(char *p, size_t n) {
intptr_t a, b, x, y;
KERNTRACE("MunmapShadow(%p, %'zu)", p, n);
a = ((intptr_t)p >> 3) + 0x7fff8000;
b = a + (n >> 3);
if (IsMemtracked(FRAME(a), FRAME(b - 1))) {
x = ROUNDUP(a, FRAMESIZE);
y = ROUNDDOWN(b, FRAMESIZE);
if (0 && x < y) {
// delete shadowspace if unmapping ≥512kb. in practice it has
// to be >1mb since we can only unmap it if it's aligned, and
// as such we poison the edges if there are any.
__repstosb((void *)a, kAsanUnmapped, x - a);
Munmap((void *)x, y - x);
__repstosb((void *)y, kAsanUnmapped, b - y);
} else {
// otherwise just poison and assume reuse
__repstosb((void *)a, kAsanUnmapped, b - a);
}
} else {
STRACE("unshadow(%.12p, %p) EFAULT", a, b - a);
}
}
// our api supports doing things like munmap(0, 0x7fffffffffff) but some
// platforms (e.g. openbsd) require that we know the specific intervals
// or else it returns EINVAL. so we munmap a piecewise.
static noasan void MunmapImpl(char *p, size_t n) {
char *q;
size_t m;
intptr_t a, b, c;
int i, l, r, rc, beg, end;
KERNTRACE("MunmapImpl(%p, %'zu)", p, n);
l = FRAME(p);
r = FRAME(p + n - 1);
i = FindMemoryInterval(&_mmi, l);
for (; i < _mmi.i && r >= _mmi.p[i].x; ++i) {
if (l >= _mmi.p[i].x && r <= _mmi.p[i].y) {
// it's contained within the entry
beg = l;
end = r;
} else if (l <= _mmi.p[i].x && r >= _mmi.p[i].x) {
// it overlaps with the lefthand side of the entry
beg = _mmi.p[i].x;
end = MIN(r, _mmi.p[i].y);
} else if (l <= _mmi.p[i].y && r >= _mmi.p[i].y) {
// it overlaps with the righthand side of the entry
beg = MAX(_mmi.p[i].x, l);
end = _mmi.p[i].y;
} else {
// shouldn't be possible
assert(!"binary search panic");
continue;
}
// openbsd even requires that if we mapped, for instance a 5 byte
// file, that we be sure to call munmap(file, 5). let's abstract!
a = ADDR(beg);
b = ADDR(end) + FRAMESIZE;
c = ADDR(_mmi.p[i].x) + _mmi.p[i].size;
q = (char *)a;
m = MIN(b, c) - a;
if (!IsWindows()) {
rc = sys_munmap(q, m);
assert(!rc);
} else {
// Handled by UntrackMemoryIntervals() on Windows
}
if (IsAsan() && !OverlapsShadowSpace(p, n)) {
MunmapShadow(q, m);
}
}
}
static noasan int Munmap(char *p, size_t n) {
unsigned i;
char poison;
intptr_t a, b, x, y;
assert(!__vforked);
if (UNLIKELY(!n)) {
STRACE("n=0");
return einval();
}
if (UNLIKELY(!IsLegalSize(n))) {
STRACE("n isn't 48-bit");
return einval();
}
if (UNLIKELY(!IsLegalPointer(p))) {
STRACE("p isn't 48-bit");
return einval();
}
if (UNLIKELY(!IsLegalPointer(p + (n - 1)))) {
STRACE("p+(n-1) isn't 48-bit");
return einval();
}
if (UNLIKELY(!ALIGNED(p))) {
STRACE("p isn't 64kb aligned");
return einval();
}
MunmapImpl(p, n);
return UntrackMemoryIntervals(p, n);
}
/**
* Releases memory pages.
*
* @param p is the beginning of the memory region to unmap
* @param n is the number of bytes to be unmapped
* @return 0 on success, or -1 w/ errno
* @raises EINVAL if `n == 0`
* @raises EINVAL if `n` isn't 48-bit
* @raises EINVAL if `p+(n-1)` isn't 48-bit
* @raises EINVAL if `p` isn't 65536-byte aligned
*/
int munmap(void *p, size_t n) {
int rc;
size_t toto;
__mmi_lock();
rc = Munmap(p, n);
#if SYSDEBUG
toto = __strace > 0 ? GetMemtrackSize(&_mmi) : 0;
#endif
__mmi_unlock();
STRACE("munmap(%.12p, %'zu) → %d% m (%'zu bytes total)", p, n, rc, toto);
return rc;
}