HLE/SVC: Implement UnmapMemoryBlock.

This implementation will need to be (almost completely) changed when we implement multiprocess support.

src/core/hle/kernel/shared_memory.cpp

@@ -39,6 +39,12 @@ ResultCode SharedMemory::Map(VAddr address, MemoryPermission permissions,
             ErrorSummary::InvalidArgument, ErrorLevel::Permanent);
     }
 
+    // TODO(Subv): Return E0E01BEE when permissions and other_permissions don't
+    // match what was specified when the memory block was created.
+
+    // TODO(Subv): Return E0E01BEE when address should be 0.
+    // Note: Find out when that's the case.
+
     if (fixed_address != 0) {
          if (address != 0 && address != fixed_address) {
             LOG_ERROR(Kernel, "cannot map id=%u, address=0x%08X name=%s: fixed_addres is 0x%08X!",
@@ -74,6 +80,21 @@ ResultCode SharedMemory::Map(VAddr address, MemoryPermission permissions,
     return RESULT_SUCCESS;
 }
 
+ResultCode SharedMemory::Unmap(VAddr address) {
+    if (base_address == 0) {
+        // TODO(Subv): Verify what actually happens when you want to unmap a memory block that
+        // was originally mapped with address = 0
+        return ResultCode(ErrorDescription::InvalidAddress, ErrorModule::OS, ErrorSummary::InvalidArgument, ErrorLevel::Usage);
+    }
+
+    if (base_address != address)
+        return ResultCode(ErrorDescription::WrongAddress, ErrorModule::OS, ErrorSummary::InvalidState, ErrorLevel::Usage);
+
+    base_address = 0;
+
+    return RESULT_SUCCESS;
+}
+
 u8* SharedMemory::GetPointer(u32 offset) {
     if (base_address != 0)
         return Memory::GetPointer(base_address + offset);

src/core/hle/kernel/shared_memory.h

@@ -52,6 +52,13 @@ public:
      */
     ResultCode Map(VAddr address, MemoryPermission permissions, MemoryPermission other_permissions);
 
+    /**
+     * Unmaps a shared memory block from the specified address in system memory
+     * @param address Address in system memory where the shared memory block is mapped
+     * @return Result code of the unmap operation
+     */
+    ResultCode Unmap(VAddr address);
+
     /**
     * Gets a pointer to the shared memory block
     * @param offset Offset from the start of the shared memory block to get pointer