int NaClFindAddressSpace(uintptr_t *addr, size_t memory_size) {
return NaClFindAddressSpaceRandomized(addr, memory_size, 0);
}
/*
* NaClAllocatePow2AlignedMemory is for allocating a large amount of
* memory of mem_sz bytes that must be address aligned, so that
* log_alignment low-order address bits must be zero.
*
* Returns the aligned region on success, or NULL on failure.
*/
static void *NaClAllocatePow2AlignedMemory(size_t mem_sz,
size_t log_alignment,
enum NaClAslrMode aslr_mode) {
uintptr_t pow2align;
size_t request_size;
uintptr_t unrounded_addr;
uintptr_t rounded_addr;
size_t extra;
int found_memory;
pow2align = ((uintptr_t) 1) << log_alignment;
request_size = mem_sz + pow2align;
NaClLog(4,
"%"MSGWIDTH"s %016"NACL_PRIxS"\n",
" Ask:",
request_size);
if (NACL_ENABLE_ASLR == aslr_mode) {
found_memory = NaClFindAddressSpaceRandomized(
&unrounded_addr,
request_size,
MAX_ADDRESS_RANDOMIZATION_ATTEMPTS);
} else {
found_memory = NaClFindAddressSpace(&unrounded_addr, request_size);
}
if (!found_memory) {
NaClLog(LOG_FATAL,
"NaClAllocatePow2AlignedMemory: Failed to reserve %"NACL_PRIxS
" bytes of address space\n",
request_size);
}
NaClLog(4,
"%"MSGWIDTH"s %016"NACL_PRIxPTR"\n",
"orig memory at",
unrounded_addr);
rounded_addr = (unrounded_addr + (pow2align - 1)) & ~(pow2align - 1);
extra = rounded_addr - unrounded_addr;
if (0 != extra) {
NaClLog(4,
"%"MSGWIDTH"s %016"NACL_PRIxPTR", %016"NACL_PRIxS"\n",
"Freeing front:",
unrounded_addr,
extra);
if (-1 == munmap((void *) unrounded_addr, extra)) {
perror("munmap (front)");
NaClLog(LOG_FATAL,
"NaClAllocatePow2AlignedMemory: munmap front failed\n");
}
}
extra = pow2align - extra;
if (0 != extra) {
NaClLog(4,
"%"MSGWIDTH"s %016"NACL_PRIxPTR", %016"NACL_PRIxS"\n",
"Freeing tail:",
rounded_addr + mem_sz,
extra);
if (-1 == munmap((void *) (rounded_addr + mem_sz),
extra)) {
perror("munmap (end)");
NaClLog(LOG_FATAL,
"NaClAllocatePow2AlignedMemory: munmap tail failed\n");
}
}
NaClLog(4,
"%"MSGWIDTH"s %016"NACL_PRIxPTR"\n",
"Aligned memory:",
rounded_addr);
/*
* we could also mmap again at rounded_addr w/o MAP_NORESERVE etc to
* ensure that we have the memory, but that's better done in another
* utility function. the semantics here is no paging space
* reserved, as in Windows MEM_RESERVE without MEM_COMMIT.
*/
return (void *) rounded_addr;
}
