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Simplify memory manager

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This commit is contained in:
Justine Tunney 2024-07-04 10:52:16 -07:00
parent 5a9a08d1cf
commit 01587de761
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GPG key ID: BE714B4575D6E328
40 changed files with 451 additions and 311 deletions
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63
libc/intrin/mprotect.c
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@ -59,56 +59,57 @@ int __mprotect(char *addr, size_t size, int prot) {
return 0;
// unix checks prot before checking size
int pagesz = getauxval(AT_PAGESZ);
if ((intptr_t)addr & (pagesz - 1))
int pagesz = getpagesize();
if (((intptr_t)addr & (pagesz - 1)) || (uintptr_t)addr + size < size)
return einval();
// normalize size
size = (size + pagesz - 1) & -pagesz;
// change mappings
int rc = 0;
__maps_lock();
struct Dll *cur;
bool found = false;
struct Map *map = __maps.maps;
struct Map **prev = &__maps.maps;
while (map) {
if (__maps_lock()) {
__maps_unlock();
return edeadlk();
}
for (cur = dll_first(__maps.used); cur; cur = dll_next(__maps.used, cur)) {
struct Map *map = MAP_CONTAINER(cur);
char *map_addr = map->addr;
size_t map_size = map->size;
struct Map *next = map->next;
char *beg = MAX(addr, map_addr);
char *end = MIN(addr + PGUP(size), map_addr + PGUP(map_size));
char *end = MIN(addr + size, map_addr + PGUP(map_size));
if (beg < end) {
found = true;
if (addr <= map_addr && addr + PGUP(size) >= map_addr + PGUP(map_size)) {
if (addr <= map_addr && addr + size >= map_addr + PGUP(map_size)) {
// change protection of entire mapping
if (!__mprotect_chunk(map_addr, map_size, prot, map->iscow)) {
map->prot = prot;
} else {
rc = -1;
}
} else if (IsWindows()) {
// windows does allow changing protection at 4096 byte chunks
// however we currently don't have data structures that track
// this within the 64 kb map granules that can't be broken up
if (__mprotect_chunk(beg, end - beg, prot, map->iscow) == -1)
rc = -1;
} else if (addr <= map_addr) {
// cleave lefthand side of mapping
// change lefthand side of mapping
size_t left = PGUP(addr + size - map_addr);
size_t right = map_size - left;
struct Map *leftmap;
if ((leftmap = __maps_alloc())) {
if (!__mprotect_chunk(map_addr, left, prot, false)) {
leftmap->next = map;
leftmap->addr = map_addr;
leftmap->size = left;
leftmap->prot = prot;
leftmap->off = map->off;
leftmap->flags = map->flags;
leftmap->iscow = map->iscow;
leftmap->readonlyfile = map->readonlyfile;
leftmap->hand = map->hand;
map->addr += left;
map->size = right;
map->hand = -1;
if (!(map->flags & MAP_ANONYMOUS))
map->off += left;
dll_make_first(&__maps.used, &leftmap->elem);
*prev = leftmap;
__maps.count += 1;
__maps_check();
} else {
@ -118,26 +119,28 @@ int __mprotect(char *addr, size_t size, int prot) {
} else {
rc = -1;
}
} else if (addr + PGUP(size) >= map_addr + PGUP(map_size)) {
// cleave righthand side of mapping
} else if (addr + size >= map_addr + PGUP(map_size)) {
// change righthand side of mapping
size_t left = addr - map_addr;
size_t right = map_addr + map_size - addr;
struct Map *leftmap;
if ((leftmap = __maps_alloc())) {
if (!__mprotect_chunk(map_addr + left, right, prot, false)) {
leftmap->next = map;
leftmap->addr = map_addr;
leftmap->size = left;
leftmap->off = map->off;
leftmap->prot = map->prot;
leftmap->flags = map->flags;
leftmap->iscow = map->iscow;
leftmap->readonlyfile = map->readonlyfile;
leftmap->hand = map->hand;
map->addr += left;
map->size = right;
map->prot = prot;
map->hand = -1;
if (!(map->flags & MAP_ANONYMOUS))
map->off += left;
dll_make_first(&__maps.used, &leftmap->elem);
*prev = leftmap;
__maps.count += 1;
__maps_check();
} else {
@ -148,34 +151,36 @@ int __mprotect(char *addr, size_t size, int prot) {
rc = -1;
}
} else {
// punch hole in mapping
// change middle of mapping
size_t left = addr - map_addr;
size_t middle = PGUP(size);
size_t middle = size;
size_t right = map_size - middle - left;
struct Map *leftmap;
if ((leftmap = __maps_alloc())) {
struct Map *midlmap;
if ((midlmap = __maps_alloc())) {
if (!__mprotect_chunk(map_addr + left, middle, prot, false)) {
leftmap->next = midlmap;
leftmap->addr = map_addr;
leftmap->size = left;
leftmap->off = map->off;
leftmap->prot = map->prot;
leftmap->flags = map->flags;
midlmap->next = map;
leftmap->iscow = map->iscow;
leftmap->readonlyfile = map->readonlyfile;
leftmap->hand = map->hand;
midlmap->addr = map_addr + left;
midlmap->size = middle;
midlmap->off = (map->flags & MAP_ANONYMOUS) ? 0 : map->off + left;
midlmap->prot = prot;
midlmap->flags = map->flags;
midlmap->hand = -1;
map->addr += left + middle;
map->size = right;
map->hand = -1;
if (!(map->flags & MAP_ANONYMOUS))
map->off += left + middle;
dll_make_first(&__maps.used, &leftmap->elem);
dll_make_first(&__maps.used, &midlmap->elem);
*prev = leftmap;
dll_make_first(&__maps.used, &leftmap->elem);
__maps.count += 2;
__maps_check();
} else {
@ -192,8 +197,6 @@ int __mprotect(char *addr, size_t size, int prot) {
}
}
}
prev = &map->next;
map = next;
}
// allow user to change mappings unknown to cosmo runtime