From ddf69464149d0e750249b0e83f8fe4fe018d2b2d Mon Sep 17 00:00:00 2001
From: SDK Chan <sdkchan@eden-emu.dev>
Date: Thu, 21 Aug 2025 12:30:20 +0000
Subject: [PATCH] [core] Finalize AliasRegionExtraSize

---
 src/core/hle/kernel/k_page_table_base.cpp  | 17 +++++++++++++++++
 src/core/hle/kernel/k_page_table_base.h    | 16 +++++-----------
 src/core/hle/kernel/k_process_page_table.h |  2 +-
 src/core/hle/kernel/svc_types.h            |  8 ++++++--
 4 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/core/hle/kernel/k_page_table_base.cpp b/src/core/hle/kernel/k_page_table_base.cpp
index 19cdf4f3ac..ea4d3d67ad 100644
--- a/src/core/hle/kernel/k_page_table_base.cpp
+++ b/src/core/hle/kernel/k_page_table_base.cpp
@@ -290,6 +290,23 @@ Result KPageTableBase::InitializeForProcess(Svc::CreateProcessFlag as_type, bool
         alloc_start = process_code_end;
         alloc_size = GetInteger(end) - GetInteger(process_code_end);
     }
+
+    // FW 18+: Apply extra region size calculations for already available region size
+    const auto as_mask = Svc::CreateProcessFlag::AddressSpaceMask;
+    const bool is_64bit_as = (as_type & as_mask) == Svc::CreateProcessFlag::AddressSpace64Bit;
+
+    if (is_64bit_as && (as_type & Svc::CreateProcessFlag::EnableAliasRegionExtraSize)
+        != static_cast<Svc::CreateProcessFlag>(0) && alias_region_size) {
+        const size_t address_space_size = (GetInteger(end) - GetInteger(start));
+
+        // Same as address_space_size/8 but faster due to bit shifting operation
+        const size_t alias_region_extra_size = address_space_size >> 3;
+        alias_region_size += alias_region_extra_size;
+
+        // Store for later processing
+        m_alias_region_extra_size = alias_region_extra_size;
+    }
+
     const size_t needed_size =
         (alias_region_size + heap_region_size + stack_region_size + kernel_map_region_size);
     R_UNLESS(alloc_size >= needed_size, ResultOutOfMemory);
diff --git a/src/core/hle/kernel/k_page_table_base.h b/src/core/hle/kernel/k_page_table_base.h
index d0921356cf..fc5d3876c7 100644
--- a/src/core/hle/kernel/k_page_table_base.h
+++ b/src/core/hle/kernel/k_page_table_base.h
@@ -211,6 +211,7 @@ private:
     size_t m_mapped_unsafe_physical_memory{};
     size_t m_mapped_insecure_memory{};
     size_t m_mapped_ipc_server_memory{};
+    size_t m_alias_region_extra_size{};
     mutable KLightLock m_general_lock;
     mutable KLightLock m_map_physical_memory_lock;
     KLightLock m_device_map_lock;
@@ -698,6 +699,10 @@ public:
         return m_alias_code_region_end - m_alias_code_region_start;
     }
 
+    size_t GetAliasRegionExtraSize() const {
+        return m_alias_region_extra_size;
+    }
+
     size_t GetNormalMemorySize() const {
         // Lock the table.
         KScopedLightLock lk(m_general_lock);
@@ -718,17 +723,6 @@ public:
         return m_address_space_width;
     }
 
-    size_t CalculateAliasRegionExtraSize() const {
-        const size_t baseline = 64ull << 30;   // Mostly appropriate for DRAM values <= 8GB
-        const size_t region = GetAliasRegionSize();
-
-        if (region > baseline) {
-            return region - baseline;
-        }
-
-        return 0;
-    }
-
 public:
     // Linear mapped
     static u8* GetLinearMappedVirtualPointer(KernelCore& kernel, KPhysicalAddress addr) {
diff --git a/src/core/hle/kernel/k_process_page_table.h b/src/core/hle/kernel/k_process_page_table.h
index 6890a2d40e..0601f9f6d8 100644
--- a/src/core/hle/kernel/k_process_page_table.h
+++ b/src/core/hle/kernel/k_process_page_table.h
@@ -414,7 +414,7 @@ public:
         return m_page_table.GetAliasRegionSize();
     }
     size_t GetAliasRegionExtraSize() const {
-        return m_page_table.CalculateAliasRegionExtraSize();
+        return m_page_table.GetAliasRegionExtraSize();
     }
     size_t GetStackRegionSize() const {
         return m_page_table.GetStackRegionSize();
diff --git a/src/core/hle/kernel/svc_types.h b/src/core/hle/kernel/svc_types.h
index d02548ba73..5e573df5da 100644
--- a/src/core/hle/kernel/svc_types.h
+++ b/src/core/hle/kernel/svc_types.h
@@ -153,7 +153,7 @@ enum class InfoType : u32 {
     ThreadTickCount = 25,
     IsSvcPermitted = 26,
     IoRegionHint = 27,
-    AliasRegionExtraSize = 28,
+    AliasRegionExtraSize = 28,
 
     MesosphereMeta = 65000,
     MesosphereCurrentProcess = 65001,
@@ -643,9 +643,13 @@ enum class CreateProcessFlag : u32 {
     // 11.x+ DisableDeviceAddressSpaceMerge.
     DisableDeviceAddressSpaceMerge = (1 << 12),
 
+    // 18.x+ Add extra size to the already available AliasRegionSize
+    EnableAliasRegionExtraSize = (1 << 13),
+
     // Mask of all flags.
     All = Is64Bit | AddressSpaceMask | EnableDebug | EnableAslr | IsApplication |
-          PoolPartitionMask | OptimizeMemoryAllocation | DisableDeviceAddressSpaceMerge,
+          PoolPartitionMask | OptimizeMemoryAllocation | DisableDeviceAddressSpaceMerge |
+          EnableAliasRegionExtraSize,
 };
 DECLARE_ENUM_FLAG_OPERATORS(CreateProcessFlag);