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better virtual base lookup algo for apple

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Signed-off-by: lizzie <lizzie@eden-emu.dev>
This commit is contained in:
lizzie 2025-09-21 04:16:12 +00:00 • committed by crueter
parent 46fca6c149
commit 7f00b0b885
1 changed files with 54 additions and 6 deletions
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60
src/common/host_memory.cpp
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@ -389,18 +389,65 @@ private:
#ifdef ARCHITECTURE_arm64
static void* ChooseVirtualBase(size_t virtual_size) {
constexpr uintptr_t Map39BitSize = (1ULL << 39);
constexpr uintptr_t Map36BitSize = (1ULL << 36);
// This is not a cryptographic application, we just want something random.
std::mt19937_64 rng;
#ifdef __APPLE__
// TODO: Fatal flaw, regions may change if map inserts elements, very rare, but MAY HAPPEN!
std::map<u64, u64> aspace_list;
kern_return_t krc = KERN_SUCCESS;
vm_address_t address = 0;
vm_size_t r_size = 0;
uint32_t depth = 1;
do {
struct vm_region_submap_info_64 info;
mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
krc = vm_region_recurse_64(mach_task_self(), &address, &r_size, &depth, (vm_region_info_64_t)&info, &count);
if (krc == KERN_INVALID_ADDRESS)
break;
if (info.is_submap){
depth++;
} else {
aspace_list.insert({ u64(address), u64(r_size) });
address += r_size;
}
} while(1);
for (auto it = aspace_list.begin(); it != aspace_list.end(); it++) {
auto const next = std::next(it);
// properties of hole
auto const addr = it->first + it->second;
auto const size = (next != aspace_list.end()) ? next->first - addr : std::numeric_limits<u64>::max() - addr;
ASSERT(next == aspace_list.end() || it->first < next->first);
if (size > virtual_size && uintptr_t(addr + size) >= Map36BitSize) {
// valid address for NCE
if (uintptr_t(addr) >= Map36BitSize) { //common case: hole after 39 bit
if (size >= virtual_size) {
void* p = mmap(reinterpret_cast<void*>(addr), virtual_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED)
continue;
return p;
}
// skip
} else { //edge case: hole before 39 bit
auto const rem_size = size - (Map36BitSize - uintptr_t(addr));
if (rem_size >= virtual_size) {
void* p = mmap(reinterpret_cast<void*>(Map36BitSize), virtual_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED)
continue;
return p;
}
// skip
}
}
}
UNREACHABLE();
#else
constexpr uintptr_t Map39BitSize = (1ULL << 39);
// We want to ensure we are allocating at an address aligned to the L2 block size.
// For Qualcomm devices, we must also allocate memory above 36 bits.
const size_t lower = Map36BitSize / HugePageSize;
const size_t upper = (Map39BitSize - virtual_size) / HugePageSize;
const size_t range = upper - lower;
// This is not a cryptographic application, we just want something random.
std::mt19937_64 rng;
// Try up to 64 times to allocate memory at random addresses in the range.
for (int i = 0; i < 64; i++) {
// Calculate a possible location.
@ -424,6 +471,7 @@ static void* ChooseVirtualBase(size_t virtual_size) {
}
return MAP_FAILED;
#endif
}
#else