From 231f708c62bb2939dff269875316bbebcac59e37 Mon Sep 17 00:00:00 2001
From: "K. Lange" <klange@toaruos.org>
Date: Mon, 22 Jan 2024 07:24:15 +0900
Subject: [PATCH] x86_64: Use 0x516 as magic signal return address

---
 kernel/arch/x86_64/idt.c  | 4 ++--
 kernel/arch/x86_64/user.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/arch/x86_64/idt.c b/kernel/arch/x86_64/idt.c
index e3fbef74..7120b1f9 100644
--- a/kernel/arch/x86_64/idt.c
+++ b/kernel/arch/x86_64/idt.c
@@ -499,8 +499,8 @@ static void _page_fault(struct regs * r) {
 	uintptr_t faulting_address;
 	asm volatile("mov %%cr2, %0" : "=r"(faulting_address));
 
-	/* 8DEADBEEFh is the magic ret-from-sig address. */
-	if (faulting_address == 0x8DEADBEEF) {
+	/* magic ret-from-sig address */
+	if (faulting_address == 0x516) {
 		return_from_signal_handler(r);
 		return;
 	}
diff --git a/kernel/arch/x86_64/user.c b/kernel/arch/x86_64/user.c
index d8ba1e88..1c9ea9b6 100644
--- a/kernel/arch/x86_64/user.c
+++ b/kernel/arch/x86_64/user.c
@@ -138,7 +138,7 @@ void arch_enter_signal_handler(uintptr_t entrypoint, int signum, struct regs *r)
 		PUSH(ret.rsp, uint64_t, this_core->current_process->thread.fp_regs[i]);
 	}
 
-	PUSH(ret.rsp, uintptr_t, 0x00000008DEADBEEF);
+	PUSH(ret.rsp, uintptr_t, 0x516);
 
 	update_process_times_on_exit();