kern: add InfoType_TransferMemoryHint

libraries/libmesosphere/include/mesosphere/kern_k_transfer_memory.hpp

@@ -48,6 +48,22 @@ namespace ams::kern {
             KProcess *GetOwner() const { return m_owner; }
             KProcessAddress GetSourceAddress() { return m_address; }
             size_t GetSize() const { return m_is_initialized ? GetReference(m_page_group).GetNumPages() * PageSize : 0; }
+
+            constexpr uintptr_t GetHint() const {
+                /* Get memory size. */
+                const size_t size = this->GetSize();
+
+                /* TODO: Is this architecture specific? */
+                if (size >= 2_MB) {
+                    return GetInteger(m_address) & (2_MB - 1);
+                } else if (size >= 64_KB) {
+                    return GetInteger(m_address) & (64_KB - 1);
+                } else if (size >= 4_KB) {
+                    return GetInteger(m_address) & (4_KB - 1);
+                } else {
+                    return 0;
+                }
+            }
     };
 
 }

libraries/libmesosphere/source/svc/kern_svc_info.cpp

@@ -314,6 +314,19 @@ namespace ams::kern::svc {
                         *out = io_region->GetHint();
                     }
                     break;
+                case ams::svc::InfoType_TransferMemoryHint:
+                    {
+                        /* Verify the sub-type is valid. */
+                        R_UNLESS(info_subtype == 0, svc::ResultInvalidCombination());
+
+                        /* Get the transfer memory from its handle. */
+                        KScopedAutoObject transfer_memory = GetCurrentProcess().GetHandleTable().GetObject<KTransferMemory>(handle);
+                        R_UNLESS(transfer_memory.IsNotNull(), svc::ResultInvalidHandle());
+
+                        /* Get the transfer memory's address hint. */
+                        *out = transfer_memory->GetHint();
+                    }
+                    break;
                 case ams::svc::InfoType_MesosphereMeta:
                     {
                         /* Verify the handle is invalid. */

libraries/libvapours/include/vapours/svc/svc_types_common.hpp

@@ -191,6 +191,8 @@ namespace ams::svc {
         InfoType_IsSvcPermitted                 = 26,
         InfoType_IoRegionHint                   = 27,
         InfoType_AliasRegionExtraSize           = 28,
+        /* ... */
+        InfoType_TransferMemoryHint             = 34,
 
         InfoType_MesosphereMeta                 = 65000,
         InfoType_MesosphereCurrentProcess       = 65001,