From 4bc47669aba2254d4f82c63987699f87ef8395bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Kr=C3=B6ning?=
 <martin.kroening@eonerc.rwth-aachen.de>
Date: Mon, 6 May 2024 12:27:24 +0200
Subject: [PATCH] fix(x86_64/CoreLocal): remove hardcoded field offsets
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Signed-off-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>
---
 src/arch/x86_64/kernel/core_local.rs | 4 ++--
 src/arch/x86_64/kernel/syscall.rs    | 5 ++++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/arch/x86_64/kernel/core_local.rs b/src/arch/x86_64/kernel/core_local.rs
index 1ea9278ee7..d35316dfbc 100644
--- a/src/arch/x86_64/kernel/core_local.rs
+++ b/src/arch/x86_64/kernel/core_local.rs
@@ -2,8 +2,8 @@ use alloc::boxed::Box;
 use alloc::vec::Vec;
 use core::arch::asm;
 use core::cell::{Cell, RefCell, RefMut};
-use core::ptr;
 use core::sync::atomic::Ordering;
+use core::{mem, ptr};
 
 #[cfg(feature = "smp")]
 use hermit_sync::InterruptTicketMutex;
@@ -81,7 +81,7 @@ impl CoreLocal {
 		debug_assert_ne!(VirtAddr::zero(), GsBase::read());
 		unsafe {
 			let raw: *const Self;
-			asm!("mov {}, gs:0", out(reg) raw, options(nomem, nostack, preserves_flags));
+			asm!("mov {}, gs:{}", out(reg) raw, const mem::offset_of!(Self, this), options(nomem, nostack, preserves_flags));
 			&*raw
 		}
 	}
diff --git a/src/arch/x86_64/kernel/syscall.rs b/src/arch/x86_64/kernel/syscall.rs
index 2c99d0c27c..5283f0929a 100644
--- a/src/arch/x86_64/kernel/syscall.rs
+++ b/src/arch/x86_64/kernel/syscall.rs
@@ -1,5 +1,7 @@
 use core::arch::asm;
+use core::mem;
 
+use super::core_local::CoreLocal;
 use crate::syscalls::table::SYSHANDLER_TABLE;
 
 #[no_mangle]
@@ -19,7 +21,7 @@ pub(crate) unsafe extern "C" fn syscall_handler() -> ! {
 			// switch to kernel stack
 			"swapgs",
 			"mov rcx, rsp",
-			"mov rsp, gs:32",
+			"mov rsp, gs:{core_local_kernel_stack}",
 			// save user stack pointer
 			"push rcx",
 			// copy 4th argument to rcx to adhere x86_64 ABI
@@ -42,6 +44,7 @@ pub(crate) unsafe extern "C" fn syscall_handler() -> ! {
 			"pop rdx",
 			"pop rcx",
 			"sysretq",
+			core_local_kernel_stack = const mem::offset_of!(CoreLocal, kernel_stack),
 			table = sym SYSHANDLER_TABLE,
 			options(noreturn)
 		);