From 69ef9c8a6a4dffa9dfe21e57461befa06b5e6b7d Mon Sep 17 00:00:00 2001
From: Eladash <18193363+elad335@users.noreply.github.com>
Date: Sat, 2 Dec 2023 19:04:44 +0200
Subject: [PATCH] PPU/sys_dbg: Implement self-modifying code

---
 rpcs3/Emu/Cell/PPUThread.cpp   |  9 +++-
 rpcs3/Emu/Cell/lv2/sys_dbg.cpp | 76 +++++++++++++++++++++++++++++++++-
 2 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/rpcs3/Emu/Cell/PPUThread.cpp b/rpcs3/Emu/Cell/PPUThread.cpp
index b364de5cac..c8284f0310 100644
--- a/rpcs3/Emu/Cell/PPUThread.cpp
+++ b/rpcs3/Emu/Cell/PPUThread.cpp
@@ -413,9 +413,14 @@ const auto ppu_recompiler_fallback_ghc = &ppu_recompiler_fallback;
 #endif
 
 // Get pointer to executable cache
+static ppu_intrp_func_t* ppu_ptr(u32 addr)
+{
+	return reinterpret_cast<ppu_intrp_func_t*>(vm::g_exec_addr + u64{addr} * 2);
+}
+
 static ppu_intrp_func_t& ppu_ref(u32 addr)
 {
-	return *reinterpret_cast<ppu_intrp_func_t*>(vm::g_exec_addr + u64{addr} * 2);
+	return *ppu_ptr(addr);
 }
 
 // Get interpreter cache value
@@ -710,7 +715,7 @@ extern void ppu_register_range(u32 addr, u32 size)
 	addr &= -0x10000;
 
 	// Register executable range at
-	utils::memory_commit(&ppu_ref(addr), u64{size} * 2, utils::protection::rw);
+	utils::memory_commit(ppu_ptr(addr), u64{size} * 2, utils::protection::rw);
 	ensure(vm::page_protect(addr, size, 0, vm::page_executable));
 
 	if (g_cfg.core.ppu_debug)
diff --git a/rpcs3/Emu/Cell/lv2/sys_dbg.cpp b/rpcs3/Emu/Cell/lv2/sys_dbg.cpp
index 8375a06c9f..27fa51b148 100644
--- a/rpcs3/Emu/Cell/lv2/sys_dbg.cpp
+++ b/rpcs3/Emu/Cell/lv2/sys_dbg.cpp
@@ -2,7 +2,14 @@
 #include "sys_dbg.h"
 
 #include "Emu/Cell/ErrorCodes.h"
+
+#include "Emu/Cell/PPUInterpreter.h"
 #include "Emu/Cell/Modules/sys_lv2dbg.h"
+#include "Emu/Memory/vm_locking.h"
+
+#include "util/asm.hpp"
+
+void ppu_register_function_at(u32 addr, u32 size, ppu_intrp_func_t ptr = nullptr);
 
 LOG_CHANNEL(sys_dbg);
 
@@ -21,13 +28,21 @@ error_code sys_dbg_read_process_memory(s32 pid, u32 address, u32 size, vm::ptr<v
 		return CELL_LV2DBG_ERROR_DEINVALIDARGUMENTS;
 	}
 
+	vm::writer_lock lock;
+
 	// Check if data destination is writable
 	if (!vm::check_addr(data.addr(), vm::page_writable, size))
 	{
 		return CELL_EFAULT;
 	}
 
-	std::memcpy(data.get_ptr(), vm::get_super_ptr(address), size);
+	// Check if the source is readable
+	if (!vm::check_addr(address, vm::page_readable, size))
+	{
+		return CELL_EFAULT;
+	}
+
+	std::memmove(data.get_ptr(), vm::base(address), size);
 
 	return CELL_OK;
 }
@@ -53,7 +68,64 @@ error_code sys_dbg_write_process_memory(s32 pid, u32 address, u32 size, vm::cptr
 		return CELL_EFAULT;
 	}
 
-	std::memcpy(vm::get_super_ptr(address), data.get_ptr(), size);
+	// Check destination (can be read-only actually)
+	if (!vm::check_addr(address, vm::page_readable, size))
+	{
+		return CELL_EFAULT;
+	}
+
+	vm::writer_lock lock;
+
+	// Again
+	if (!vm::check_addr(data.addr(), vm::page_readable, size) || !vm::check_addr(address, vm::page_readable, size))
+	{
+		return CELL_EFAULT;
+	}
+
+	const u8* data_ptr = static_cast<const u8*>(data.get_ptr());
+
+	if ((address >> 28) == 0xDu)
+	{
+		// Stack pages (4k pages is the exception here)
+		std::memmove(vm::base(address), data_ptr, size);
+		return CELL_OK;
+	}
+
+	const u32 end = address + size;
+
+	for (u32 i = address, exec_update_size = 0; i < end;)
+	{
+		const u32 op_size = std::min<u32>(utils::align<u32>(i + 1, 0x10000), end) - i;
+
+		const bool is_exec = vm::check_addr(i, vm::page_executable | vm::page_readable);
+
+		if (is_exec)
+		{
+			exec_update_size += op_size;
+			i += op_size;
+		}
+
+		if (!is_exec || i >= end)
+		{
+			// Commit executable data update
+			// The read memory is also super ptr so memmove can work correctly on all implementations
+			const u32 before_addr = i - exec_update_size;
+			std::memmove(vm::get_super_ptr(before_addr), vm::get_super_ptr(data.addr() + (before_addr - address)), exec_update_size);
+			ppu_register_function_at(before_addr, exec_update_size);
+			exec_update_size = 0;
+
+			if (i >= end)
+			{
+				break;
+			}
+		}
+
+		if (!is_exec)
+		{
+			std::memmove(vm::base(i), data_ptr + (i - address), op_size);
+			i += op_size;
+		}
+	}
 
 	return CELL_OK;
 }