From 7a7c5e433eb74fa19f2e159ca5442fb094ba978e Mon Sep 17 00:00:00 2001
From: Bananymous <bananymousosq@gmail.com>
Date: Sat, 23 Sep 2023 02:28:25 +0300
Subject: [PATCH] Kernel/LibC: add flag to enable/disable sse support

SSE support is very experimental and causes GP. I decided to make
SSE not default until I get to fixing it :)
---
 CMakeLists.txt                 |  3 +++
 kernel/arch/x86_64/IDT.cpp     | 10 ++++++++--
 kernel/include/kernel/Thread.h |  4 ++++
 kernel/kernel/Syscall.cpp      |  5 +++++
 libc/printf_impl.cpp           |  4 ++++
 5 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f31e35f5..f178e01c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,6 +20,9 @@ if(NOT EXISTS ${CMAKE_CXX_COMPILER})
 	set(CMAKE_CXX_COMPILER g++)
 endif()
 
+add_compile_options(-mno-sse -mno-sse2)
+add_compile_definitions(__enable_sse=0)
+
 project(banan-os CXX)
 
 set(BANAN_BASE_SYSROOT ${CMAKE_SOURCE_DIR}/base-sysroot.tar.gz)
diff --git a/kernel/arch/x86_64/IDT.cpp b/kernel/arch/x86_64/IDT.cpp
index 6f5ae8a4..9369d933 100644
--- a/kernel/arch/x86_64/IDT.cpp
+++ b/kernel/arch/x86_64/IDT.cpp
@@ -139,10 +139,11 @@ namespace IDT
 
 	extern "C" void cpp_isr_handler(uint64_t isr, uint64_t error, Kernel::InterruptStack& interrupt_stack, const Registers* regs)
 	{
+#if __enable_sse
 		bool from_userspace = (interrupt_stack.cs & 0b11) == 0b11;
-
 		if (from_userspace)
 			Kernel::Thread::current().save_sse();
+#endif
 
 		pid_t tid = Kernel::Scheduler::current_tid();
 		pid_t pid = tid ? Kernel::Process::current().pid() : 0;
@@ -205,19 +206,22 @@ namespace IDT
 
 		ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminated);
 
+#if __enable_sse
 		if (from_userspace)
 		{
 			ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);
 			Kernel::Thread::current().load_sse();
 		}
+#endif
 	}
 
 	extern "C" void cpp_irq_handler(uint64_t irq, Kernel::InterruptStack& interrupt_stack)
 	{
+#if __enable_sse
 		bool from_userspace = (interrupt_stack.cs & 0b11) == 0b11;
-
 		if (from_userspace)
 			Kernel::Thread::current().save_sse();
+#endif
 
 		if (Kernel::Scheduler::current_tid())
 		{
@@ -240,11 +244,13 @@ namespace IDT
 
 		ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminated);
 
+#if __enable_sse
 		if (from_userspace)
 		{
 			ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);
 			Kernel::Thread::current().load_sse();
 		}
+#endif
 	}
 
 	static void flush_idt()
diff --git a/kernel/include/kernel/Thread.h b/kernel/include/kernel/Thread.h
index d743d078..c4115098 100644
--- a/kernel/include/kernel/Thread.h
+++ b/kernel/include/kernel/Thread.h
@@ -82,8 +82,10 @@ namespace Kernel
 
 		bool is_userspace() const { return m_is_userspace; }
 
+#if __enable_sse
 		void save_sse() { asm volatile("fxsave %0" :: "m"(m_sse_storage)); }
 		void load_sse() { asm volatile("fxrstor %0" :: "m"(m_sse_storage)); }
+#endif
 
 	private:
 		Thread(pid_t tid, Process*);
@@ -114,7 +116,9 @@ namespace Kernel
 
 		uint64_t m_terminate_blockers { 0 };
 
+#if __enable_sse
 		alignas(16) uint8_t m_sse_storage[512] {};
+#endif
 
 		friend class Scheduler;
 	};
diff --git a/kernel/kernel/Syscall.cpp b/kernel/kernel/Syscall.cpp
index 3ea7c3df..d319e0dc 100644
--- a/kernel/kernel/Syscall.cpp
+++ b/kernel/kernel/Syscall.cpp
@@ -32,7 +32,9 @@ namespace Kernel
 			return 0;
 		}
 
+#if __enable_sse
 		Thread::current().save_sse();
+#endif
 
 		asm volatile("sti");
 
@@ -205,7 +207,10 @@ namespace Kernel
 			Kernel::panic("Kernel error while returning to userspace {}", ret.error());
 
 		ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);
+
+#if __enable_sse
 		Thread::current().load_sse();
+#endif
 
 		if (ret.is_error())
 			return -ret.error().get_error_code();
diff --git a/libc/printf_impl.cpp b/libc/printf_impl.cpp
index 99eaa92c..367edc80 100644
--- a/libc/printf_impl.cpp
+++ b/libc/printf_impl.cpp
@@ -104,6 +104,7 @@ static void integer_to_string(char* buffer, T value, int base, bool upper, forma
 	buffer[offset++] = '\0';
 }
 
+#if __enable_sse
 template<BAN::floating_point T>
 static void floating_point_to_string(char* buffer, T value, bool upper, const format_options_t options)
 {
@@ -227,6 +228,7 @@ static void floating_point_to_exponent_string(char* buffer, T value, bool upper,
 	exponent_options.width = 3;
 	integer_to_string<int>(buffer + offset, exponent, 10, upper, exponent_options);
 }
+#endif
 
 extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun)(int, void*), void* data)
 {
@@ -349,6 +351,7 @@ extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun
 				format++;
 				break;
 			}
+#if __enable_sse
 			case 'e':
 			case 'E':
 			{
@@ -367,6 +370,7 @@ extern "C" int printf_impl(const char* format, va_list arguments, int (*putc_fun
 				format++;
 				break;
 			}
+#endif
 			case 'g':
 			case 'G':
 				// TODO