[core/loader] Implement a bit improper ASLR (#2945)

A bit improper of an ASLR - it does something but something good? Who knows...
All I know is that there is a non-uniform distrobution for rand() and that rng_seed is likely a better solution?
I don't know

Signed-off-by: lizzie lizzie@eden-emu.dev

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2945
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

1 files changed, 6 insertions, 10 deletions

diff --git a/src/core/hle/kernel/k_process.cpp b/src/core/hle/kernel/k_process.cpp
index 355a2a5f3b..322f971ba3 100644
--- a/src/core/hle/kernel/k_process.cpp
+++ b/src/core/hle/kernel/k_process.cpp
@@ -28,9 +28,6 @@ namespace Kernel {
 
 namespace {
 
-// TODO: Remove this workaround when proper ASLR is implemented for all address spaces.
-constexpr u64 CodeStartOffset = 0x500000UL;
-
 Result TerminateChildren(KernelCore& kernel, KProcess* process,
                          const KThread* thread_to_not_terminate) {
     // Request that all children threads terminate.
@@ -1157,7 +1154,7 @@ KProcess::KProcess(KernelCore& kernel)
 KProcess::~KProcess() = default;
 
 Result KProcess::LoadFromMetadata(const FileSys::ProgramMetadata& metadata, std::size_t code_size,
-                                  KProcessAddress aslr_space_start, bool is_hbl) {
+    KProcessAddress aslr_space_start, size_t aslr_space_offset, bool is_hbl) {
     // Create a resource limit for the process.
     const auto pool = static_cast<KMemoryManager::Pool>(metadata.GetPoolPartition());
     const auto physical_memory_size = m_kernel.MemoryManager().GetSize(pool);
@@ -1187,25 +1184,24 @@ Result KProcess::LoadFromMetadata(const FileSys::ProgramMetadata& metadata, std:
     // Set the address space type and code address.
     switch (metadata.GetAddressSpaceType()) {
     case FileSys::ProgramAddressSpaceType::Is39Bit:
-        flag |= Svc::CreateProcessFlag::AddressSpace64Bit;
-
         // For 39-bit processes, the ASLR region starts at 0x800'0000 and is ~512GiB large.
         // However, some (buggy) programs/libraries like skyline incorrectly depend on the
         // existence of ASLR pages before the entry point, so we will adjust the load address
         // to point to about 2GiB into the ASLR region.
-        code_address = 0x8000'0000;
+        flag |= Svc::CreateProcessFlag::AddressSpace64Bit;
+        code_address = 0x8000'0000 + aslr_space_offset;
         break;
     case FileSys::ProgramAddressSpaceType::Is36Bit:
         flag |= Svc::CreateProcessFlag::AddressSpace64BitDeprecated;
-        code_address = 0x800'0000;
+        code_address = 0x800'0000 + aslr_space_offset;
         break;
     case FileSys::ProgramAddressSpaceType::Is32Bit:
         flag |= Svc::CreateProcessFlag::AddressSpace32Bit;
-        code_address = 0x20'0000 + CodeStartOffset;
+        code_address = 0x20'0000 + aslr_space_offset;
         break;
     case FileSys::ProgramAddressSpaceType::Is32BitNoMap:
         flag |= Svc::CreateProcessFlag::AddressSpace32BitWithoutAlias;
-        code_address = 0x20'0000 + CodeStartOffset;
+        code_address = 0x20'0000 + aslr_space_offset;
         break;
     }