From c622539b95f495c769533de21a9bb92c6f1e045a Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Thu, 23 Jul 2020 00:58:44 -0700
Subject: [PATCH] kern: SvcSetMemoryPermission

---
 .../source/kern_k_page_table_base.cpp         | 30 ++++++++++++++++-
 .../source/svc/kern_svc_memory.cpp            | 33 +++++++++++++++++--
 2 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/libraries/libmesosphere/source/kern_k_page_table_base.cpp b/libraries/libmesosphere/source/kern_k_page_table_base.cpp
index 4075ce182..cf59c3b0e 100644
--- a/libraries/libmesosphere/source/kern_k_page_table_base.cpp
+++ b/libraries/libmesosphere/source/kern_k_page_table_base.cpp
@@ -1021,7 +1021,35 @@ namespace ams::kern {
     }
 
     Result KPageTableBase::SetMemoryPermission(KProcessAddress addr, size_t size, ams::svc::MemoryPermission svc_perm) {
-        MESOSPHERE_UNIMPLEMENTED();
+        const size_t num_pages = size / PageSize;
+
+        /* Lock the table. */
+        KScopedLightLock lk(this->general_lock);
+
+        /* Verify we can change the memory permission. */
+        KMemoryState old_state;
+        KMemoryPermission old_perm;
+        R_TRY(this->CheckMemoryState(std::addressof(old_state), std::addressof(old_perm), nullptr, addr, size, KMemoryState_FlagCanReprotect, KMemoryState_FlagCanReprotect, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_All, KMemoryAttribute_None));
+
+        /* Determine new perm. */
+        const KMemoryPermission new_perm = ConvertToKMemoryPermission(svc_perm);
+        R_SUCCEED_IF(old_perm == new_perm);
+
+        /* Create an update allocator. */
+        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
+        R_TRY(allocator.GetResult());
+
+        /* We're going to perform an update, so create a helper. */
+        KScopedPageTableUpdater updater(this);
+
+        /* Perform mapping operation. */
+        const KPageProperties properties = { new_perm, false, false, false };
+        R_TRY(this->Operate(updater.GetPageList(), addr, num_pages, Null<KPhysicalAddress>, false, properties, OperationType_ChangePermissions, false));
+
+        /* Update the blocks. */
+        this->memory_block_manager.Update(&allocator, addr, num_pages, old_state, new_perm, KMemoryAttribute_None);
+
+        return ResultSuccess();
     }
 
     Result KPageTableBase::SetProcessMemoryPermission(KProcessAddress addr, size_t size, ams::svc::MemoryPermission svc_perm) {
diff --git a/libraries/libmesosphere/source/svc/kern_svc_memory.cpp b/libraries/libmesosphere/source/svc/kern_svc_memory.cpp
index a4a64bdf9..7a8ec7891 100644
--- a/libraries/libmesosphere/source/svc/kern_svc_memory.cpp
+++ b/libraries/libmesosphere/source/svc/kern_svc_memory.cpp
@@ -21,6 +21,35 @@ namespace ams::kern::svc {
 
     namespace {
 
+        constexpr bool IsValidSetMemoryPermission(ams::svc::MemoryPermission perm) {
+            switch (perm) {
+                case ams::svc::MemoryPermission_None:
+                case ams::svc::MemoryPermission_Read:
+                case ams::svc::MemoryPermission_ReadWrite:
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
+        Result SetMemoryPermission(uintptr_t address, size_t size, ams::svc::MemoryPermission perm) {
+            /* Validate address / size. */
+            R_UNLESS(util::IsAligned(address, PageSize), svc::ResultInvalidAddress());
+            R_UNLESS(util::IsAligned(size,    PageSize), svc::ResultInvalidSize());
+            R_UNLESS(size > 0,                           svc::ResultInvalidSize());
+            R_UNLESS((address < address + size),         svc::ResultInvalidCurrentMemory());
+
+            /* Validate the permission. */
+            R_UNLESS(IsValidSetMemoryPermission(perm), svc::ResultInvalidNewMemoryPermission());
+
+            /* Validate that the region is in range for the current process. */
+            auto &page_table = GetCurrentProcess().GetPageTable();
+            R_UNLESS(page_table.Contains(address, size), svc::ResultInvalidCurrentMemory());
+
+            /* Set the memory attribute. */
+            return page_table.SetMemoryPermission(address, size, perm);
+        }
+
         Result SetMemoryAttribute(uintptr_t address, size_t size, uint32_t mask, uint32_t attr) {
             /* Validate address / size. */
             R_UNLESS(util::IsAligned(address, PageSize), svc::ResultInvalidAddress());
@@ -97,7 +126,7 @@ namespace ams::kern::svc {
     /* =============================    64 ABI    ============================= */
 
     Result SetMemoryPermission64(ams::svc::Address address, ams::svc::Size size, ams::svc::MemoryPermission perm) {
-        MESOSPHERE_PANIC("Stubbed SvcSetMemoryPermission64 was called.");
+        return SetMemoryPermission(address, size, perm);
     }
 
     Result SetMemoryAttribute64(ams::svc::Address address, ams::svc::Size size, uint32_t mask, uint32_t attr) {
@@ -115,7 +144,7 @@ namespace ams::kern::svc {
     /* ============================= 64From32 ABI ============================= */
 
     Result SetMemoryPermission64From32(ams::svc::Address address, ams::svc::Size size, ams::svc::MemoryPermission perm) {
-        MESOSPHERE_PANIC("Stubbed SvcSetMemoryPermission64From32 was called.");
+        return SetMemoryPermission(address, size, perm);
     }
 
     Result SetMemoryAttribute64From32(ams::svc::Address address, ams::svc::Size size, uint32_t mask, uint32_t attr) {