From da76f651ec20ac3b5cb8ace65f543d246a6c8f0a Mon Sep 17 00:00:00 2001
From: OatmealDome <julian@oatmealdome.me>
Date: Sun, 27 Sep 2026 13:47:37 -0400
Subject: [PATCH] MemArenaDarwin: Eliminate use of mach_make_memory_entry_64

---
 Source/Core/Common/MemArena.h         |  1 -
 Source/Core/Common/MemArenaDarwin.cpp | 56 +++++++++------------------
 2 files changed, 19 insertions(+), 38 deletions(-)

diff --git a/Source/Core/Common/MemArena.h b/Source/Core/Common/MemArena.h
index 1a3093cc4d..9186bb0739 100644
--- a/Source/Core/Common/MemArena.h
+++ b/Source/Core/Common/MemArena.h
@@ -144,7 +144,6 @@ private:
 #elif defined(__APPLE__)
   vm_address_t m_shm_address = 0;
   vm_size_t m_shm_size = 0;
-  mem_entry_name_port_t m_shm_entry = MACH_PORT_NULL;
 
   vm_address_t m_region_address = 0;
   vm_size_t m_region_size = 0;
diff --git a/Source/Core/Common/MemArenaDarwin.cpp b/Source/Core/Common/MemArenaDarwin.cpp
index 0f6db28339..691660f462 100644
--- a/Source/Core/Common/MemArenaDarwin.cpp
+++ b/Source/Core/Common/MemArenaDarwin.cpp
@@ -25,36 +25,11 @@ void MemArena::GrabSHMSegment(size_t size, std::string_view base_name)
     return;
   }
 
-  memory_object_size_t entry_size = size;
-  // Large anonymous mappings are split into 128 MB chunks. Without MAP_MEM_VM_SHARE,
-  // mach_make_memory_entry_64 will only return an entry spanning the first chunk.
-  // Attempting to map through that entry will fail if it extends beyond the 128 MB
-  // boundary, which can happen when the sizes of MEM1/MEM2 are overridden.
-  constexpr vm_prot_t prot = VM_PROT_READ | VM_PROT_WRITE | MAP_MEM_VM_SHARE;
-
-  retval = mach_make_memory_entry_64(mach_task_self(), &entry_size, m_shm_address, prot,
-                                     &m_shm_entry, MACH_PORT_NULL);
-  if (retval != KERN_SUCCESS)
-  {
-    ERROR_LOG_FMT(MEMMAP, "GrabSHMSegment failed: mach_make_memory_entry_64 returned {0:#x}",
-                  retval);
-
-    m_shm_address = 0;
-    m_shm_entry = MACH_PORT_NULL;
-
-    return;
-  }
-
   m_shm_size = size;
 }
 
 void MemArena::ReleaseSHMSegment()
 {
-  if (m_shm_entry != MACH_PORT_NULL)
-  {
-    mach_port_deallocate(mach_task_self(), m_shm_entry);
-  }
-
   if (m_shm_address != 0)
   {
     vm_deallocate(mach_task_self(), m_shm_address, m_shm_size);
@@ -62,7 +37,6 @@ void MemArena::ReleaseSHMSegment()
 
   m_shm_address = 0;
   m_shm_size = 0;
-  m_shm_entry = MACH_PORT_NULL;
 }
 
 void* MemArena::CreateView(s64 offset, size_t size)
@@ -74,13 +48,15 @@ void* MemArena::CreateView(s64 offset, size_t size)
   }
 
   vm_address_t address = 0;
-  constexpr vm_prot_t prot = VM_PROT_READ | VM_PROT_WRITE;
+  vm_prot_t current_protection;
+  vm_prot_t maximum_protection;
 
-  kern_return_t retval = vm_map(mach_task_self(), &address, size, 0, VM_FLAGS_ANYWHERE, m_shm_entry,
-                                offset, false, prot, prot, VM_INHERIT_DEFAULT);
+  kern_return_t retval = vm_remap(mach_task_self(), &address, size, 0, VM_FLAGS_ANYWHERE,
+                                  mach_task_self(), m_shm_address + offset, false,
+                                  &current_protection, &maximum_protection, VM_INHERIT_DEFAULT);
   if (retval != KERN_SUCCESS)
   {
-    ERROR_LOG_FMT(MEMMAP, "CreateView failed: vm_map returned {0:#x}", retval);
+    ERROR_LOG_FMT(MEMMAP, "CreateView failed: vm_remap returned {0:#x}", retval);
     return nullptr;
   }
 
@@ -136,16 +112,22 @@ void* MemArena::MapInMemoryRegion(s64 offset, size_t size, void* base, bool writ
   }
 
   vm_address_t address = reinterpret_cast<vm_address_t>(base);
-  vm_prot_t prot = VM_PROT_READ;
-  if (writeable)
-    prot |= VM_PROT_WRITE;
+  vm_prot_t current_protection;
+  vm_prot_t maximum_protection;
+
+  kern_return_t retval = vm_remap(
+      mach_task_self(), &address, size, 0, VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE, mach_task_self(),
+      m_shm_address + offset, false, &current_protection, &maximum_protection, VM_INHERIT_DEFAULT);
 
-  kern_return_t retval =
-      vm_map(mach_task_self(), &address, size, 0, VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE, m_shm_entry,
-             offset, false, prot, VM_PROT_READ | VM_PROT_WRITE, VM_INHERIT_DEFAULT);
   if (retval != KERN_SUCCESS)
   {
-    ERROR_LOG_FMT(MEMMAP, "MapInMemoryRegion failed: vm_map returned {0:#x}", retval);
+    ERROR_LOG_FMT(MEMMAP, "MapInMemoryRegion failed: vm_remap returned {0:#x}", retval);
+    return nullptr;
+  }
+
+  if (!ChangeMappingProtection(reinterpret_cast<void*>(address), size, writeable))
+  {
+    UnmapFromMemoryRegion(reinterpret_cast<void*>(address), size);
     return nullptr;
   }