2 files changed, 67 insertions, 29 deletions

diff --git a/src/common/host_memory.cpp b/src/common/host_memory.cpp
index 41ca12ab0..a66fc49e2 100644
--- a/src/common/host_memory.cpp
+++ b/src/common/host_memory.cpp
@@ -32,6 +32,7 @@
 
 #include "common/alignment.h"
 #include "common/assert.h"
+#include "common/free_region_manager.h"
 #include "common/host_memory.h"
 #include "common/logging/log.h"
 
@@ -339,6 +340,11 @@ private:
         return false;
     }
 
+    void EnableDirectMappedAddress() {
+        // TODO
+        UNREACHABLE();
+    }
+
     HANDLE process{};        ///< Current process handle
     HANDLE backing_handle{}; ///< File based backing memory
 
@@ -472,7 +478,7 @@ public:
             }
         }
 #else
-        virtual_base = static_cast<u8*>(ChooseVirtualBase(virtual_size));
+        virtual_base = virtual_map_base = static_cast<u8*>(ChooseVirtualBase(virtual_size));
         if (virtual_base == MAP_FAILED) {
             LOG_CRITICAL(HW_Memory, "mmap failed: {}", strerror(errno));
             throw std::bad_alloc{};
@@ -480,7 +486,7 @@ public:
         madvise(virtual_base, virtual_size, MADV_HUGEPAGE);
 #endif
 
-        placeholders.add({0, virtual_size});
+        free_manager.SetAddressSpace(virtual_base, virtual_size);
         good = true;
     }
 
@@ -489,10 +495,11 @@ public:
     }
 
     void Map(size_t virtual_offset, size_t host_offset, size_t length) {
-        {
-            std::scoped_lock lock{placeholder_mutex};
-            placeholders.subtract({virtual_offset, virtual_offset + length});
-        }
+        // Intersect the range with our address space.
+        AdjustMap(&virtual_offset, &length);
+
+        // We are removing a placeholder.
+        free_manager.AllocateBlock(virtual_base + virtual_offset, length);
 
         void* ret = mmap(virtual_base + virtual_offset, length, PROT_READ | PROT_WRITE,
                          MAP_SHARED | MAP_FIXED, fd, host_offset);
@@ -503,26 +510,23 @@ public:
         // The method name is wrong. We're still talking about the virtual range.
         // We don't want to unmap, we want to reserve this memory.
 
-        {
-            std::scoped_lock lock{placeholder_mutex};
-            auto it = placeholders.find({virtual_offset - 1, virtual_offset + length + 1});
+        // Intersect the range with our address space.
+        AdjustMap(&virtual_offset, &length);
 
-            if (it != placeholders.end()) {
-                size_t prev_upper = virtual_offset + length;
-                virtual_offset = std::min(virtual_offset, it->lower());
-                length = std::max(it->upper(), prev_upper) - virtual_offset;
-            }
+        // Merge with any adjacent placeholder mappings.
+        auto [merged_pointer, merged_size] =
+            free_manager.FreeBlock(virtual_base + virtual_offset, length);
 
-            placeholders.add({virtual_offset, virtual_offset + length});
-        }
-
-        void* ret = mmap(virtual_base + virtual_offset, length, PROT_NONE,
+        void* ret = mmap(merged_pointer, merged_size, PROT_NONE,
                          MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
         ASSERT_MSG(ret != MAP_FAILED, "mmap failed: {}", strerror(errno));
     }
 
     void Protect(size_t virtual_offset, size_t length, bool read, bool write) {
-        int flags = 0;
+        // Intersect the range with our address space.
+        AdjustMap(&virtual_offset, &length);
+
+        int flags = PROT_NONE;
         if (read) {
             flags |= PROT_READ;
         }
@@ -533,17 +537,22 @@ public:
         ASSERT_MSG(ret == 0, "mprotect failed: {}", strerror(errno));
     }
 
+    void EnableDirectMappedAddress() {
+        virtual_base = nullptr;
+    }
+
     const size_t backing_size; ///< Size of the backing memory in bytes
     const size_t virtual_size; ///< Size of the virtual address placeholder in bytes
 
     u8* backing_base{reinterpret_cast<u8*>(MAP_FAILED)};
     u8* virtual_base{reinterpret_cast<u8*>(MAP_FAILED)};
+    u8* virtual_map_base{reinterpret_cast<u8*>(MAP_FAILED)};
 
 private:
     /// Release all resources in the object
     void Release() {
-        if (virtual_base != MAP_FAILED) {
-            int ret = munmap(virtual_base, virtual_size);
+        if (virtual_map_base != MAP_FAILED) {
+            int ret = munmap(virtual_map_base, virtual_size);
             ASSERT_MSG(ret == 0, "munmap failed: {}", strerror(errno));
         }
 
@@ -558,10 +567,29 @@ private:
         }
     }
 
-    int fd{-1}; // memfd file descriptor, -1 is the error value of memfd_create
+    void AdjustMap(size_t* virtual_offset, size_t* length) {
+        if (virtual_base != nullptr) {
+            return;
+        }
+
+        // If we are direct mapped, we want to make sure we are operating on a region
+        // that is in range of our virtual mapping.
+        size_t intended_start = *virtual_offset;
+        size_t intended_end = intended_start + *length;
+        size_t address_space_start = reinterpret_cast<size_t>(virtual_map_base);
+        size_t address_space_end = address_space_start + virtual_size;
 
-    boost::icl::interval_set<size_t> placeholders; ///< Mapped placeholders
-    std::mutex placeholder_mutex;                  ///< Mutex for placeholders
+        if (address_space_start > intended_end || intended_start > address_space_end) {
+            *virtual_offset = 0;
+            *length = 0;
+        } else {
+            *virtual_offset = std::max(intended_start, address_space_start);
+            *length = std::min(intended_end, address_space_end) - *virtual_offset;
+        }
+    }
+
+    int fd{-1}; // memfd file descriptor, -1 is the error value of memfd_create
+    FreeRegionManager free_manager{};
 };
 
 #else // ^^^ Linux ^^^ vvv Generic vvv
@@ -591,15 +619,16 @@ HostMemory::HostMemory(size_t backing_size_, size_t virtual_size_)
     try {
         // Try to allocate a fastmem arena.
         // The implementation will fail with std::bad_alloc on errors.
-        impl = std::make_unique<HostMemory::Impl>(AlignUp(backing_size, PageAlignment),
-                                                  AlignUp(virtual_size, PageAlignment) +
-                                                      3 * HugePageSize);
+        impl =
+            std::make_unique<HostMemory::Impl>(AlignUp(backing_size, PageAlignment),
+                                               AlignUp(virtual_size, PageAlignment) + HugePageSize);
         backing_base = impl->backing_base;
         virtual_base = impl->virtual_base;
 
         if (virtual_base) {
-            virtual_base += 2 * HugePageSize - 1;
-            virtual_base -= reinterpret_cast<size_t>(virtual_base) & (HugePageSize - 1);
+            // Ensure the virtual base is aligned to the L2 block size.
+            virtual_base = reinterpret_cast<u8*>(
+                Common::AlignUp(reinterpret_cast<uintptr_t>(virtual_base), HugePageSize));
             virtual_base_offset = virtual_base - impl->virtual_base;
         }
 
@@ -650,4 +679,11 @@ void HostMemory::Protect(size_t virtual_offset, size_t length, bool read, bool w
     impl->Protect(virtual_offset + virtual_base_offset, length, read, write);
 }
 
+void HostMemory::EnableDirectMappedAddress() {
+    if (impl) {
+        impl->EnableDirectMappedAddress();
+        virtual_size += reinterpret_cast<uintptr_t>(virtual_base);
+    }
+}
+
 } // namespace Common
diff --git a/src/common/host_memory.h b/src/common/host_memory.h
index 447975ded..4014a1962 100644
--- a/src/common/host_memory.h
+++ b/src/common/host_memory.h
@@ -37,6 +37,8 @@ public:
 
     void Protect(size_t virtual_offset, size_t length, bool read, bool write);
 
+    void EnableDirectMappedAddress();
+
     [[nodiscard]] u8* BackingBasePointer() noexcept {
         return backing_base;
     }