From f73bb242f3f8757230a0e85385d468533e453607 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 27 Jun 2025 21:51:13 +0300
Subject: [PATCH] Kernel: Save fpu state and flags in signal handler

This was causing some weird crashes :D
---
 kernel/arch/i686/Signal.S   | 11 +++++++----
 kernel/arch/x86_64/Signal.S |  7 +++++++
 kernel/kernel/Thread.cpp    |  1 +
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/kernel/arch/i686/Signal.S b/kernel/arch/i686/Signal.S
index 4bf29015..9c3f0542 100644
--- a/kernel/arch/i686/Signal.S
+++ b/kernel/arch/i686/Signal.S
@@ -7,9 +7,6 @@
 
 .global signal_trampoline
 signal_trampoline:
-	pushl %ebp
-	movl %esp, %ebp
-
 	pusha
 
 	movl 40(%esp), %edi
@@ -19,16 +16,22 @@ signal_trampoline:
 	movl %esp, %ebp
 	andl $-16, %esp
 
+	subl $512, %esp
+	fxsave (%esp)
+
 	subl $12, %esp
 	pushl %edi
 	call *%eax
 	addl $16, %esp
 
+	fxrstor (%esp)
+	addl $512, %esp
+
 	// restore stack
 	movl %ebp, %esp
 	popa
 
-	leave
 	addl $8, %esp
+	popf
 
 	ret
diff --git a/kernel/arch/x86_64/Signal.S b/kernel/arch/x86_64/Signal.S
index c3259a68..bb6397dd 100644
--- a/kernel/arch/x86_64/Signal.S
+++ b/kernel/arch/x86_64/Signal.S
@@ -30,8 +30,14 @@ signal_trampoline:
 	movq %rsp, %rbp
 	andq $-16, %rsp
 
+	subq $512, %rsp
+	fxsave64 (%rsp)
+
 	call *%rax
 
+	fxrstor64 (%rsp)
+	addq $512, %rsp
+
 	// restore stack
 	movq %rbp, %rsp
 	popq %r15
@@ -51,6 +57,7 @@ signal_trampoline:
 	popq %rax
 
 	addq $16, %rsp
+	popfq
 
 	// return over red-zone
 	ret $128
diff --git a/kernel/kernel/Thread.cpp b/kernel/kernel/Thread.cpp
index fb0f838f..f1a54ed6 100644
--- a/kernel/kernel/Thread.cpp
+++ b/kernel/kernel/Thread.cpp
@@ -523,6 +523,7 @@ namespace Kernel
 			interrupt_stack.sp -= 128; // skip possible red-zone
 #endif
 			write_to_stack(interrupt_stack.sp, interrupt_stack.ip);
+			write_to_stack(interrupt_stack.sp, interrupt_stack.flags);
 			write_to_stack(interrupt_stack.sp, signal);
 			write_to_stack(interrupt_stack.sp, signal_handler);
 			interrupt_stack.ip = (uintptr_t)signal_trampoline;