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Fix mmap MT bug on Windows

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This commit is contained in:
Justine Tunney 2024-10-31 23:06:06 -07:00
parent 9add248c9b
commit 913b573661
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GPG key ID: BE714B4575D6E328
2 changed files with 9 additions and 11 deletions
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3
libc/intrin/maps.h
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@ -32,7 +32,7 @@ struct Maps {
_Atomic(uintptr_t) freed; _Atomic(uintptr_t) freed;
size_t count; size_t count;
size_t pages; size_t pages;
_Atomic(char *) pick; char *pick;
struct Map stack; struct Map stack;
struct Map guard; struct Map guard;
}; };
@ -49,7 +49,6 @@ bool __maps_lock(void);
void __maps_check(void); void __maps_check(void);
void __maps_unlock(void); void __maps_unlock(void);
void *__maps_randaddr(void); void *__maps_randaddr(void);
void *__maps_pickaddr(size_t);
void __maps_add(struct Map *); void __maps_add(struct Map *);
void __maps_free(struct Map *); void __maps_free(struct Map *);
void __maps_insert(struct Map *); void __maps_insert(struct Map *);

17
libc/intrin/mmap.c
View file

@ -411,22 +411,21 @@ void *__maps_randaddr(void) {
return (void *)addr; return (void *)addr;
} }
void *__maps_pickaddr(size_t size) { static void *__maps_pickaddr(size_t size) {
char *addr; char *addr;
__maps_lock();
for (int try = 0; try < MAX_TRIES; ++try) { for (int try = 0; try < MAX_TRIES; ++try) {
addr = atomic_exchange_explicit(&__maps.pick, 0, memory_order_acq_rel); addr = __maps.pick;
__maps.pick = 0;
if (!addr) if (!addr)
addr = __maps_randaddr(); addr = __maps_randaddr();
__maps_lock(); if (!__maps_overlaps(addr, size, __pagesize)) {
bool overlaps = __maps_overlaps(addr, size, __pagesize); __maps.pick = addr + ((size + __gransize - 1) & __gransize);
__maps_unlock(); __maps_unlock();
if (!overlaps) {
atomic_store_explicit(&__maps.pick,
addr + ((size + __gransize - 1) & __gransize),
memory_order_release);
return addr; return addr;
} }
} }
__maps_unlock();
return 0; return 0;
} }