You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
91 lines
4.0 KiB
91 lines
4.0 KiB
/*-*- 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 │ |
|
│ │ |
|
│ This program is free software; you can redistribute it and/or modify │ |
|
│ it under the terms of the GNU General Public License as published by │ |
|
│ the Free Software Foundation; version 2 of the License. │ |
|
│ │ |
|
│ This program is distributed in the hope that it will be useful, but │ |
|
│ WITHOUT ANY WARRANTY; without even the implied warranty of │ |
|
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │ |
|
│ General Public License for more details. │ |
|
│ │ |
|
│ You should have received a copy of the GNU General Public License │ |
|
│ along with this program; if not, write to the Free Software │ |
|
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │ |
|
│ 02110-1301 USA │ |
|
╚─────────────────────────────────────────────────────────────────────────────*/ |
|
#include "libc/assert.h" |
|
#include "libc/bits/bits.h" |
|
#include "libc/bits/popcnt.h" |
|
#include "libc/bits/safemacros.h" |
|
#include "libc/calls/calls.h" |
|
#include "libc/runtime/buffer.h" |
|
#include "libc/runtime/mappings.h" |
|
#include "libc/runtime/runtime.h" |
|
#include "libc/str/str.h" |
|
#include "libc/sysv/consts/prot.h" |
|
|
|
#define kGuard PAGESIZE |
|
#define kGrain FRAMESIZE |
|
|
|
/** |
|
* Allocates page-guarded buffer. |
|
* |
|
* ┌─────────────────────────────────────┬s─i─g─s─e─g─v┐ |
|
* │ 𝑣₀..𝑣ₙ₋₁ │𝑣ₙ..𝑣ₙ₊₄₀₉₆₋₁│ |
|
* └─────────────────────────────────────┴s─i─g─s─e─g─v┘ |
|
* |
|
* @param b is metadata object owned by caller, initialized to zero for |
|
* first call; subsequent calls will resize |
|
* @param a is alignment requirement in bytes, e.g. 1,2,4,8,16,... |
|
* @param n is buffer size in bytes |
|
* @return b->p |
|
* @see ralloc() |
|
*/ |
|
void *balloc(struct GuardedBuffer *b, unsigned a, size_t n) { |
|
int rc; |
|
char *p; |
|
size_t mi, need; |
|
struct AddrSize az; |
|
struct MemoryCoord mc; |
|
|
|
assert(a >= 1); |
|
assert(a <= kGuard); |
|
assert(kGuard < kGrain); |
|
assert(popcnt(a) == 1); |
|
assert(popcnt(kGuard) == 1); |
|
assert(popcnt(kGrain) == 1); |
|
assert(n < 0x800000000000ul - kGrain - kGuard); |
|
|
|
if (n) { |
|
az.addr = 0; |
|
az.size = 0; |
|
n = roundup(n, a); |
|
need = roundup(n + kGuard, kGrain); |
|
if (b->p) { |
|
mc = ADDRSIZE_TO_COORD(b->p, 1); |
|
mi = findmapping(mc.y); |
|
if (mi && ISOVERLAPPING(mc, _mm.p[mi - 1])) { |
|
az = COORD_TO_ADDRSIZE(_mm.p[mi - 1]); |
|
if (az.size < need) { |
|
rc = munmap(az.addr, az.size); |
|
assert(rc != -1); |
|
az.addr = NULL; |
|
az.size = 0; |
|
} |
|
} |
|
} |
|
if (!az.size) { |
|
if ((p = mapanon(need)) == MAP_FAILED) abort(); |
|
if (mprotect(p + need - kGuard, kGuard, PROT_NONE) == -1) abort(); |
|
} else { |
|
p = az.addr; |
|
} |
|
b->p = p + need - kGuard - n; |
|
} |
|
|
|
return b->p; |
|
}
|
|
|