Implement a better heuristic to detect whether an ELF is for GC or Wii

Source/Core/Core/Src/Boot/Boot_ELF.cpp

@@ -34,12 +34,35 @@ bool CBoot::IsElfWii(const char *filename)
 	File::IOFile f(filename, "rb");
 	f.ReadBytes(mem, (size_t)filesize);
 	}
-
-	ElfReader reader(mem);
-	// TODO: Find a more reliable way to distinguish.
-	bool isWii = reader.GetEntryPoint() >= 0x80004000;
-	delete[] mem;
 	
+	// Use the same method as the DOL loader uses: search for mfspr from HID4,
+	// which should only be used in Wii ELFs.
+	// 
+	// Likely to have some false positives/negatives, patches implementing a
+	// better heuristic are welcome.
+
+	u32 HID4_pattern = 0x7c13fba6;
+	u32 HID4_mask = 0xfc1fffff;
+	ElfReader reader(mem);
+	bool isWii = false;
+
+	for (int i = 0; i < reader.GetNumSections(); ++i)
+	{
+		if (reader.IsCodeSection(i))
+		{
+			for (unsigned int j = 0; j < reader.GetSectionSize(i) / sizeof (u32); ++j)
+			{
+				u32 word = Common::swap32(((u32*)reader.GetSectionDataPtr(i))[j]);
+				if ((word & HID4_mask) == HID4_pattern)
+				{
+					isWii = true;
+					break;
+				}
+			}
+		}
+	}
+
+	delete[] mem;
     return isWii;
 }
 

Source/Core/Core/Src/Boot/ElfReader.h

@@ -59,7 +59,6 @@ public:
 	bool LoadInto(u32 vaddr);
 	bool LoadSymbols();
 
-private:
 	int GetNumSegments() const { return (int)(header->e_phnum); }
 	int GetNumSections() const { return (int)(header->e_shnum); }
 	const u8 *GetPtr(int offset) const { return (u8*)base + offset; }
@@ -73,6 +72,10 @@ private:
 		else
 			return 0;
 	}
+	bool IsCodeSection(int section) const
+	{
+		return sections[section].sh_type == SHT_PROGBITS;
+	}
 	const u8 *GetSegmentPtr(int segment)
 	{
 		return GetPtr(segments[segment].p_offset);