From 249d6a490d0bf91258829e358d48bcb2c50faa27 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sun, 29 Aug 2021 12:26:40 +0200
Subject: [PATCH] Kernel: Add read_gs_value() and write_gs_value()

Co-authored-by: Tom <tomut@yahoo.com>
---
 Kernel/Arch/x86/ASM_wrapper.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Kernel/Arch/x86/ASM_wrapper.h b/Kernel/Arch/x86/ASM_wrapper.h
index 9bb508d515..187a1649d7 100644
--- a/Kernel/Arch/x86/ASM_wrapper.h
+++ b/Kernel/Arch/x86/ASM_wrapper.h
@@ -62,6 +62,25 @@ ALWAYS_INLINE u16 get_gs()
 }
 #endif
 
+template<typename T>
+ALWAYS_INLINE T read_gs_value(FlatPtr offset)
+{
+    T val;
+    asm volatile(
+        "mov %%gs:%a[off], %[val]"
+        : [val] "=r"(val)
+        : [off] "ir"(offset));
+    return val;
+}
+
+template<typename T>
+ALWAYS_INLINE void write_gs_value(FlatPtr offset, T val)
+{
+    asm volatile(
+        "mov %[val], %%gs:%a[off]" ::[off] "ir"(offset), [val] "r"(val)
+        : "memory");
+}
+
 ALWAYS_INLINE FlatPtr read_gs_ptr(FlatPtr offset)
 {
     FlatPtr val;