mem: implement most of StandardAllocator

This was tested using `https://github.com/node-dot-cpp/alloc-test` plus a few other by-hand tests.

It seems to work for the case we care about (sysmodules without thread cache-ing).

External users are advised to build with assertions on and contact SciresM if you find issues.

This is a lot of code to have gotten right in one go, and it was written mostly after midnight while sick, so there are probably un-noticed issues.

libraries/libstratosphere/source/os/impl/os_memory_permission_impl.hpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+#include <stratosphere.hpp>
+
+namespace ams::os::impl {
+
+    void SetMemoryPermissionImpl(uintptr_t address, size_t size, MemoryPermission perm);
+
+}

libraries/libstratosphere/source/os/impl/os_memory_permission_impl.os.horizon.cpp

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stratosphere.hpp>
+
+namespace ams::os::impl {
+
+    namespace {
+
+        void SetMemoryPermissionBySvc(uintptr_t start, size_t size, svc::MemoryPermission perm) {
+            uintptr_t cur_address = start;
+            size_t remaining_size = size;
+            while (remaining_size > 0) {
+                svc::MemoryInfo mem_info;
+                svc::PageInfo page_info;
+                R_ABORT_UNLESS(svc::QueryMemory(std::addressof(mem_info), std::addressof(page_info), cur_address));
+
+                size_t cur_size = std::min(mem_info.addr + mem_info.size - cur_address, remaining_size);
+
+                if (mem_info.perm != perm) {
+                    R_ABORT_UNLESS(svc::SetMemoryPermission(cur_address, cur_size, perm));
+                }
+
+                cur_address += cur_size;
+                remaining_size -= cur_size;
+            }
+        }
+
+    }
+
+    void SetMemoryPermissionImpl(uintptr_t address, size_t size, MemoryPermission perm) {
+        switch (perm) {
+            case MemoryPermission_None:
+                return SetMemoryPermissionBySvc(address, size, svc::MemoryPermission_None);
+            case MemoryPermission_ReadOnly:
+                return SetMemoryPermissionBySvc(address, size, svc::MemoryPermission_Read);
+            case MemoryPermission_ReadWrite:
+                return SetMemoryPermissionBySvc(address, size, svc::MemoryPermission_ReadWrite);
+            AMS_UNREACHABLE_DEFAULT_CASE();
+        }
+    }
+
+}