// Expand or shrink a chunk returned by allocate_chunk().
// The chunk is never moved.
//
// Returns 0 if fail to expand (shrink will always succeed). Returns old
// size if successful.
size_t OsMemory_adjust_chunk(address chunk_ptr, size_t new_committed_size) {
ChunkInfo* ci = get_chunk_info(chunk_ptr);
size_t old_size = ci->size;
size_t new_size = page_align_up(new_committed_size);
if (new_size <= ci->mmaped_size) {
int rv;
if (new_size < old_size) {
rv = protect_area(chunk_ptr + new_size, old_size - new_size);
} else {
rv = unprotect_area(chunk_ptr, new_size);
}
GUARANTEE(rv == 0, "mprotect must succeed");
ci->size = new_size;
return old_size;
}
new_size = page_align_up(new_size - ci->mmaped_size);
if (anon_mmap(chunk_ptr + ci->mmaped_size, new_size) == NULL) {
return 0;
}
ci->mmaped_size += new_size;
ci->size = ci->mmaped_size;
unprotect_area(chunk_ptr, ci->size);
return old_size;
}
address OsMemory_allocate_chunk(size_t initial_size,
size_t max_size, size_t alignment)
{
// make it page aligned
max_size = page_align_up(max_size);
address chunk = anon_mmap(NULL, max_size);
if (chunk == MAP_FAILED) {
return NULL;
}
GUARANTEE((juint)chunk % alignment == 0, "must be aligned");
GUARANTEE((juint)chunk % SysPageSize == 0, "must be page aligned");
size_t aligned_size = page_align_up(initial_size);
alloc_chunk(chunk, aligned_size, max_size);
if (max_size > aligned_size) {
protect_area(chunk + aligned_size, max_size - aligned_size);
}
return chunk;
}
protected_area_ptr
new_protected_area(BytePtr start, BytePtr end, lisp_protection_kind reason, natural protsize, Boolean now)
{
protected_area_ptr p = malloc(sizeof(protected_area));
if (p == NULL) return NULL;
p->protsize = protsize;
p->nprot = 0;
p->start = start;
p->end = end;
p->why = reason;
p->next = AllProtectedAreas;
AllProtectedAreas = p;
if (now) {
protect_area(p);
}
return p;
}