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Rewrite brk() and sbrk()

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This change reduces the .bss memory requirement for all executables by
O(64kb). The brk system calls are now fully tested and figured out and
might be useful for tiny programs that only target System Five.
This commit is contained in:
Justine Tunney 2022-10-01 23:11:56 -07:00
parent bc8532688b
commit 5005f2e446
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
23 changed files with 643 additions and 294 deletions
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45
libc/intrin/bitop.h
View file

@ -1,45 +0,0 @@
#ifndef COSMOPOLITAN_LIBC_BITS_BITOP_H_
#define COSMOPOLITAN_LIBC_BITS_BITOP_H_
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_
#define bts(MEM, BIT) __BitOp("bts", BIT, MEM) /** bit test and set */
#define btr(MEM, BIT) __BitOp("btr", BIT, MEM) /** bit test and reset */
#define btc(MEM, BIT) __BitOp("btc", BIT, MEM) /** bit test and complement */
#define lockbts(MEM, BIT) __BitOp("lock bts", BIT, MEM)
#define lockbtr(MEM, BIT) __BitOp("lock btr", BIT, MEM)
#define lockbtc(MEM, BIT) __BitOp("lock btc", BIT, MEM)
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
#define __BitOp(OP, BIT, MEM) \
({ \
bool OldBit; \
if (__builtin_constant_p(BIT)) { \
asm(CFLAG_ASM(OP "%z1\t%2,%1") \
: CFLAG_CONSTRAINT(OldBit), \
"+m"((MEM)[(BIT) / (sizeof((MEM)[0]) * CHAR_BIT)]) \
: "J"((BIT) % (sizeof((MEM)[0]) * CHAR_BIT)) \
: "cc"); \
} else if (sizeof((MEM)[0]) == 2) { \
asm(CFLAG_ASM(OP "\t%w2,%1") \
: CFLAG_CONSTRAINT(OldBit), "+m"((MEM)[0]) \
: "r"(BIT) \
: "cc"); \
} else if (sizeof((MEM)[0]) == 4) { \
asm(CFLAG_ASM(OP "\t%k2,%1") \
: CFLAG_CONSTRAINT(OldBit), "+m"((MEM)[0]) \
: "r"(BIT) \
: "cc"); \
} else if (sizeof((MEM)[0]) == 8) { \
asm(CFLAG_ASM(OP "\t%q2,%1") \
: CFLAG_CONSTRAINT(OldBit), "+m"((MEM)[0]) \
: "r"(BIT) \
: "cc"); \
} \
OldBit; \
})
#endif /* __GNUC__ && !__STRICT_ANSI__ */
COSMOPOLITAN_C_END_
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
#endif /* COSMOPOLITAN_LIBC_BITS_BITOP_H_ */

11
libc/intrin/describeframe.c
View file

@ -19,7 +19,9 @@
#include "libc/dce.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/weaken.h"
#include "libc/macros.internal.h"
#include "libc/runtime/brk.internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/winargs.internal.h"
@ -28,6 +30,11 @@
#define UNSHADOW(x) ((int64_t)(MAX(0, (x)-0x7fff8000)) << 3)
#define FRAME(x) ((int)((x) >> 16))
forceinline pureconst bool IsBrkFrame(int x) {
unsigned char *p = (unsigned char *)((intptr_t)((uintptr_t)x << 32) >> 16);
return _weaken(__brk) && p >= _end && p < _weaken(__brk)->p;
}
static const char *GetFrameName(int x) {
if (!x) {
return "null";
@ -41,6 +48,8 @@ static const char *GetFrameName(int x) {
return "arena";
} else if (IsStaticStackFrame(x)) {
return "stack";
} else if (IsBrkFrame(x)) {
return "brk";
} else if (IsGfdsFrame(x)) {
return "g_fds";
} else if (IsZiposFrame(x)) {
@ -68,7 +77,7 @@ static const char *GetFrameName(int x) {
const char *(DescribeFrame)(char buf[32], int x) {
char *p;
if (IsShadowFrame(x)) {
ksnprintf(buf, 64, "%s %s %.8x", GetFrameName(x),
ksnprintf(buf, 32, "%s %s %.8x", GetFrameName(x),
GetFrameName(FRAME(UNSHADOW(ADDR(x)))), FRAME(UNSHADOW(ADDR(x))));
return buf;
} else {

37
libc/intrin/findmemoryinterval.c Normal file
View file

@ -0,0 +1,37 @@
/*-*- 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 2022 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/intrin/midpoint.h"
#include "libc/runtime/memtrack.internal.h"
noasan unsigned FindMemoryInterval(const struct MemoryIntervals *mm, int x) {
unsigned l, m, r;
l = 0;
r = mm->i;
while (l < r) {
m = _midpoint(l, r);
if (mm->p[m].y < x) {
l = m + 1;
} else {
r = m;
}
}
_unassert(l == mm->i || x <= mm->p[l].y);
return l;
}

12
libc/intrin/kprintf.greg.c
View file

@ -43,6 +43,7 @@
#include "libc/nt/runtime.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/nt/winsock.h"
#include "libc/runtime/brk.internal.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
@ -103,8 +104,17 @@ privileged static inline bool kistextpointer(const void *p) {
return _base <= (const unsigned char *)p && (const unsigned char *)p < _etext;
}
privileged static inline unsigned char *kend(void) {
unsigned char *p;
if (_weaken(__brk) && (p = _weaken(__brk)->p)) {
return p;
} else {
return _end;
}
}
privileged static inline bool kisimagepointer(const void *p) {
return _base <= (const unsigned char *)p && (const unsigned char *)p < _end;
return _base <= (const unsigned char *)p && (const unsigned char *)p < kend();
}
privileged static inline bool kischarmisaligned(const char *p, signed char t) {