From d562bb841d3dfea91dca9f340f014c794ad23c32 Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Fri, 22 Oct 2021 09:33:53 -0700
Subject: [PATCH] kern: add toggleable support for 40-bit physaddr caps

---
 .../include/mesosphere/kern_build_config.hpp         | 11 ++++++++++-
 .../include/mesosphere/kern_k_capabilities.hpp       | 12 +++++++++++-
 .../libmesosphere/source/kern_k_capabilities.cpp     | 10 +++++++---
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/libraries/libmesosphere/include/mesosphere/kern_build_config.hpp b/libraries/libmesosphere/include/mesosphere/kern_build_config.hpp
index 8216bab0c..cb0de2781 100644
--- a/libraries/libmesosphere/include/mesosphere/kern_build_config.hpp
+++ b/libraries/libmesosphere/include/mesosphere/kern_build_config.hpp
@@ -38,4 +38,13 @@
 /* at the cost of storing class tokens inside the class object. */
 /* However, as of (10/16/2021) KAutoObject has an unused class member */
 /* of the right side, and so this does not actually cost any space. */
-#define MESOSPHERE_ENABLE_DEVIRTUALIZED_DYNAMIC_CAST
\ No newline at end of file
+#define MESOSPHERE_ENABLE_DEVIRTUALIZED_DYNAMIC_CAST
+
+/* NOTE: This uses currently-reserved bits inside the MapRange capability */
+/* in order to support large physical addresses (40-bit instead of 36). */
+/* This is toggleable in order to disable it if N ever uses those bits. */
+#if defined(ATMOSPHERE_BOARD_NINTENDO_NX)
+//#define MESOSPHERE_ENABLE_LARGE_PHYSICAL_ADDRESS_CAPABILITIES
+#else
+#define MESOSPHERE_ENABLE_LARGE_PHYSICAL_ADDRESS_CAPABILITIES
+#endif
\ No newline at end of file
diff --git a/libraries/libmesosphere/include/mesosphere/kern_k_capabilities.hpp b/libraries/libmesosphere/include/mesosphere/kern_k_capabilities.hpp
index fd69590b8..3c31124d8 100644
--- a/libraries/libmesosphere/include/mesosphere/kern_k_capabilities.hpp
+++ b/libraries/libmesosphere/include/mesosphere/kern_k_capabilities.hpp
@@ -82,7 +82,11 @@ namespace ams::kern {
                 DEFINE_FIELD(Index, Mask,    3);
             };
 
+            #if defined(MESOSPHERE_ENABLE_LARGE_PHYSICAL_ADDRESS_CAPABILITIES)
+            static constexpr u64 PhysicalMapAllowedMask = (1ul << 40) - 1;
+            #else
             static constexpr u64 PhysicalMapAllowedMask = (1ul << 36) - 1;
+            #endif
 
             struct MapRange {
                 using IdBits = Field<0, CapabilityId<CapabilityType::MapRange> + 1>;
@@ -94,9 +98,15 @@ namespace ams::kern {
             struct MapRangeSize {
                 using IdBits = Field<0, CapabilityId<CapabilityType::MapRange> + 1>;
 
-                DEFINE_FIELD(Pages,    IdBits,   20);
+                DEFINE_FIELD(Pages, IdBits, 20);
+
+                #if defined(MESOSPHERE_ENABLE_LARGE_PHYSICAL_ADDRESS_CAPABILITIES)
+                DEFINE_FIELD(AddressHigh, Pages,        4);
+                DEFINE_FIELD(Normal,      AddressHigh,  1, bool);
+                #else
                 DEFINE_FIELD(Reserved, Pages,     4);
                 DEFINE_FIELD(Normal,   Reserved,  1, bool);
+                #endif
             };
 
             struct MapIoPage {
diff --git a/libraries/libmesosphere/source/kern_k_capabilities.cpp b/libraries/libmesosphere/source/kern_k_capabilities.cpp
index d2000e632..1aa8f4999 100644
--- a/libraries/libmesosphere/source/kern_k_capabilities.cpp
+++ b/libraries/libmesosphere/source/kern_k_capabilities.cpp
@@ -117,11 +117,15 @@ namespace ams::kern {
     }
 
     Result KCapabilities::MapRange(const util::BitPack32 cap, const util::BitPack32 size_cap, KProcessPageTable *page_table) {
+        /* Get/validate address/size */
+        #if defined(MESOSPHERE_ENABLE_LARGE_PHYSICAL_ADDRESS_CAPABILITIES)
+        const u64 phys_addr    = static_cast<u64>(cap.Get<MapRange::Address>() | (size_cap.Get<MapRangeSize::AddressHigh>() << MapRange::Address::Count)) * PageSize;
+        #else
+        const u64 phys_addr    = static_cast<u64>(cap.Get<MapRange::Address>()) * PageSize;
+
         /* Validate reserved bits are unused. */
         R_UNLESS(size_cap.Get<MapRangeSize::Reserved>() == 0, svc::ResultOutOfRange());
-
-        /* Get/validate address/size */
-        const u64 phys_addr    = cap.Get<MapRange::Address>() * PageSize;
+        #endif
         const size_t num_pages = size_cap.Get<MapRangeSize::Pages>();
         const size_t size      = num_pages * PageSize;
         R_UNLESS(phys_addr == GetInteger(KPhysicalAddress(phys_addr)),    svc::ResultInvalidAddress());