vm/sys_memory: Remove VM locking in sys_memory_get_page_attribute

Author: elad335

rpcs3/Emu/Cell/lv2/sys_memory.cpp

@@ -5,6 +5,7 @@
 #include "Emu/CPU/CPUThread.h"
 #include "Emu/Cell/ErrorCodes.h"
 #include "Emu/Cell/SPUThread.h"
+#include "Emu/Cell/PPUThread.h"
 #include "Emu/IdManager.h"
 
 #include "util/asm.hpp"
@@ -247,17 +248,37 @@ error_code sys_memory_free(cpu_thread& cpu, u32 addr)
 	return CELL_OK;
 }
 
-error_code sys_memory_get_page_attribute(cpu_thread& cpu, u32 addr, vm::ptr<sys_page_attr_t> attr)
+error_code sys_memory_get_page_attribute(ppu_thread& ppu, u32 addr, vm::ptr<sys_page_attr_t> attr)
 {
-	cpu.state += cpu_flag::wait;
+	ppu.state += cpu_flag::wait;
 
 	sys_memory.trace("sys_memory_get_page_attribute(addr=0x%x, attr=*0x%x)", addr, attr);
 
-	vm::writer_lock rlock;
+	if ((addr >> 28) == (ppu.stack_addr >> 28))
+	{
+		// Stack address: fast path
+		if (!(addr >= ppu.stack_addr && addr < ppu.stack_addr + ppu.stack_size) && !vm::check_addr(addr))
+		{
+			return { CELL_EINVAL, addr };
+		}
+
+		if (!vm::check_addr(attr.addr(), vm::page_readable, attr.size()))
+		{
+			return CELL_EFAULT;
+		}
 
-	if (!vm::check_addr(addr) || addr >= SPU_FAKE_BASE_ADDR)
+		attr->attribute = 0x40000ull; // SYS_MEMORY_PROT_READ_WRITEs
+		attr->access_right = SYS_MEMORY_ACCESS_RIGHT_PPU_THR;
+		attr->page_size = 4096;
+		attr->pad = 0; // Always write 0
+		return CELL_OK;
+	}
+
+	const auto [ok, vm_flags] = vm::get_addr_flags(addr);
+
+	if (!ok || addr >= SPU_FAKE_BASE_ADDR)
 	{
-		return CELL_EINVAL;
+		return { CELL_EINVAL, addr };
 	}
 
 	if (!vm::check_addr(attr.addr(), vm::page_readable, attr.size()))
@@ -266,19 +287,20 @@ error_code sys_memory_get_page_attribute(cpu_thread& cpu, u32 addr, vm::ptr<sys_
 	}
 
 	attr->attribute = 0x40000ull; // SYS_MEMORY_PROT_READ_WRITE (TODO)
-	attr->access_right = addr >> 28 == 0xdu ? SYS_MEMORY_ACCESS_RIGHT_PPU_THR : SYS_MEMORY_ACCESS_RIGHT_ANY;// (TODO)
+	attr->access_right = SYS_MEMORY_ACCESS_RIGHT_ANY; // TODO: Report accurately
 
-	if (vm::check_addr(addr, vm::page_1m_size))
+	if (vm_flags & vm::page_1m_size)
 	{
 		attr->page_size = 0x100000;
 	}
-	else if (vm::check_addr(addr, vm::page_64k_size))
+	else if (vm_flags & vm::page_64k_size)
 	{
 		attr->page_size = 0x10000;
 	}
 	else
 	{
-		attr->page_size = 4096;
+		//attr->page_size = 4096;
+		fmt::throw_exception("Unreachable");
 	}
 
 	attr->pad = 0; // Always write 0

rpcs3/Emu/Cell/lv2/sys_memory.h

@@ -4,6 +4,7 @@
 #include "Emu/Cell/ErrorCodes.h"
 
 class cpu_thread;
+class ppu_thread;
 
 enum lv2_mem_container_id : u32
 {
@@ -131,7 +132,7 @@ struct sys_memory_user_memory_stat_t
 error_code sys_memory_allocate(cpu_thread& cpu, u64 size, u64 flags, vm::ptr<u32> alloc_addr);
 error_code sys_memory_allocate_from_container(cpu_thread& cpu, u64 size, u32 cid, u64 flags, vm::ptr<u32> alloc_addr);
 error_code sys_memory_free(cpu_thread& cpu, u32 start_addr);
-error_code sys_memory_get_page_attribute(cpu_thread& cpu, u32 addr, vm::ptr<sys_page_attr_t> attr);
+error_code sys_memory_get_page_attribute(ppu_thread& cpu, u32 addr, vm::ptr<sys_page_attr_t> attr);
 error_code sys_memory_get_user_memory_size(cpu_thread& cpu, vm::ptr<sys_memory_info_t> mem_info);
 error_code sys_memory_get_user_memory_stat(cpu_thread& cpu, vm::ptr<sys_memory_user_memory_stat_t> mem_stat);
 error_code sys_memory_container_create(cpu_thread& cpu, vm::ptr<u32> cid, u64 size);

rpcs3/Emu/Memory/vm.h

@@ -81,7 +81,7 @@ namespace vm
 	bool check_addr(u32 addr, u8 flags, u32 size);
 
 	template <u32 Size = 1>
-	bool check_addr(u32 addr, u8 flags = page_readable)
+	inline bool check_addr(u32 addr, u8 flags = page_readable)
 	{
 		extern std::array<memory_page, 0x100000000 / 4096> g_pages;
 
@@ -94,6 +94,16 @@ namespace vm
 		return !(~g_pages[addr / 4096] & (flags | page_allocated));
 	}
 
+	// Like check_addr but should only be used in lock-free context with care
+	inline std::pair<bool, u8> get_addr_flags(u32 addr) noexcept
+	{
+		extern std::array<memory_page, 0x100000000 / 4096> g_pages;
+
+		const u8 flags = g_pages[addr / 4096].load();
+
+		return std::make_pair(!!(flags & page_allocated), flags);
+	}
+
 	// Read string in a safe manner (page aware) (bool true = if null-termination)
 	bool read_string(u32 addr, u32 max_size, std::string& out_string, bool check_pages = true) noexcept;