From 326e7c70208865b013e138972b25687d805488d0 Mon Sep 17 00:00:00 2001
From: Yuri Kunde Schlesner <yuriks@yuriks.net>
Date: Wed, 21 Jun 2017 20:21:49 -0700
Subject: [PATCH] Memory: Make PhysicalToVirtualAddress return a
 boost::optional

And fix a few places in the code to take advantage of that.
---
 src/core/hle/kernel/shared_memory.cpp |  2 +-
 src/core/hle/service/apt/apt.cpp      |  2 +-
 src/core/memory.cpp                   | 21 ++++++++++++---------
 src/core/memory.h                     |  7 ++++---
 4 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/src/core/hle/kernel/shared_memory.cpp b/src/core/hle/kernel/shared_memory.cpp
index 922e5ab58b..a7b66142f6 100644
--- a/src/core/hle/kernel/shared_memory.cpp
+++ b/src/core/hle/kernel/shared_memory.cpp
@@ -149,7 +149,7 @@ ResultCode SharedMemory::Map(Process* target_process, VAddr address, MemoryPermi
 
     if (base_address == 0 && target_address == 0) {
         // Calculate the address at which to map the memory block.
-        target_address = Memory::PhysicalToVirtualAddress(linear_heap_phys_address);
+        target_address = Memory::PhysicalToVirtualAddress(linear_heap_phys_address).value();
     }
 
     // Map the memory block into the target process
diff --git a/src/core/hle/service/apt/apt.cpp b/src/core/hle/service/apt/apt.cpp
index 25e7b777da..6375e28f98 100644
--- a/src/core/hle/service/apt/apt.cpp
+++ b/src/core/hle/service/apt/apt.cpp
@@ -82,7 +82,7 @@ void GetSharedFont(Service::Interface* self) {
     // The shared font has to be relocated to the new address before being passed to the
     // application.
     VAddr target_address =
-        Memory::PhysicalToVirtualAddress(shared_font_mem->linear_heap_phys_address);
+        Memory::PhysicalToVirtualAddress(shared_font_mem->linear_heap_phys_address).value();
     if (!shared_font_relocated) {
         BCFNT::RelocateSharedFont(shared_font_mem, target_address);
         shared_font_relocated = true;
diff --git a/src/core/memory.cpp b/src/core/memory.cpp
index b8438e490e..7d849d55f3 100644
--- a/src/core/memory.cpp
+++ b/src/core/memory.cpp
@@ -268,7 +268,8 @@ bool IsValidVirtualAddress(const VAddr vaddr) {
 }
 
 bool IsValidPhysicalAddress(const PAddr paddr) {
-    return IsValidVirtualAddress(PhysicalToVirtualAddress(paddr));
+    boost::optional<VAddr> vaddr = PhysicalToVirtualAddress(paddr);
+    return vaddr && IsValidVirtualAddress(*vaddr);
 }
 
 u8* GetPointer(const VAddr vaddr) {
@@ -301,7 +302,8 @@ std::string ReadCString(VAddr vaddr, std::size_t max_length) {
 
 u8* GetPhysicalPointer(PAddr address) {
     // TODO(Subv): This call should not go through the application's memory mapping.
-    return GetPointer(PhysicalToVirtualAddress(address));
+    boost::optional<VAddr> vaddr = PhysicalToVirtualAddress(address);
+    return vaddr ? GetPointer(*vaddr) : nullptr;
 }
 
 void RasterizerMarkRegionCached(PAddr start, u32 size, int count_delta) {
@@ -312,8 +314,12 @@ void RasterizerMarkRegionCached(PAddr start, u32 size, int count_delta) {
     u32 num_pages = ((start + size - 1) >> PAGE_BITS) - (start >> PAGE_BITS) + 1;
     PAddr paddr = start;
 
-    for (unsigned i = 0; i < num_pages; ++i) {
-        VAddr vaddr = PhysicalToVirtualAddress(paddr);
+    for (unsigned i = 0; i < num_pages; ++i, paddr += PAGE_SIZE) {
+        boost::optional<VAddr> maybe_vaddr = PhysicalToVirtualAddress(paddr);
+        if (!maybe_vaddr)
+            continue;
+        VAddr vaddr = *maybe_vaddr;
+
         u8& res_count = current_page_table->cached_res_count[vaddr >> PAGE_BITS];
         ASSERT_MSG(count_delta <= UINT8_MAX - res_count,
                    "Rasterizer resource cache counter overflow!");
@@ -353,7 +359,6 @@ void RasterizerMarkRegionCached(PAddr start, u32 size, int count_delta) {
                 UNREACHABLE();
             }
         }
-        paddr += PAGE_SIZE;
     }
 }
 
@@ -687,7 +692,7 @@ PAddr VirtualToPhysicalAddress(const VAddr addr) {
     return addr | 0x80000000;
 }
 
-VAddr PhysicalToVirtualAddress(const PAddr addr) {
+boost::optional<VAddr> PhysicalToVirtualAddress(const PAddr addr) {
     if (addr == 0) {
         return 0;
     } else if (addr >= VRAM_PADDR && addr < VRAM_PADDR_END) {
@@ -702,9 +707,7 @@ VAddr PhysicalToVirtualAddress(const PAddr addr) {
         return addr - N3DS_EXTRA_RAM_PADDR + N3DS_EXTRA_RAM_VADDR;
     }
 
-    LOG_ERROR(HW_Memory, "Unknown physical address @ 0x%08X", addr);
-    // To help with debugging, set bit on address so that it's obviously invalid.
-    return addr | 0x80000000;
+    return boost::none;
 }
 
 } // namespace
diff --git a/src/core/memory.h b/src/core/memory.h
index 71fb278adf..77277c342c 100644
--- a/src/core/memory.h
+++ b/src/core/memory.h
@@ -7,6 +7,7 @@
 #include <array>
 #include <cstddef>
 #include <string>
+#include <boost/optional.hpp>
 #include "common/common_types.h"
 
 namespace Memory {
@@ -154,9 +155,9 @@ std::string ReadCString(VAddr virtual_address, std::size_t max_length);
 PAddr VirtualToPhysicalAddress(VAddr addr);
 
 /**
-* Undoes a mapping performed by VirtualToPhysicalAddress().
-*/
-VAddr PhysicalToVirtualAddress(PAddr addr);
+ * Undoes a mapping performed by VirtualToPhysicalAddress().
+ */
+boost::optional<VAddr> PhysicalToVirtualAddress(PAddr addr);
 
 /**
  * Gets a pointer to the memory region beginning at the specified physical address.