From 6b6133186d9eb1fb076e63013b1ed3bdaebea973 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 29 Jul 2024 01:28:58 -0400
Subject: kernel/amd64: Facilitate IA32_FS_BASE reads/writes

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/include/arch/amd64/asm.h | 12 ++++++++++++
 sys/include/arch/amd64/msr.h |  1 +
 2 files changed, 13 insertions(+)

(limited to 'sys/include')

diff --git a/sys/include/arch/amd64/asm.h b/sys/include/arch/amd64/asm.h
index e85dd87..04d5e42 100644
--- a/sys/include/arch/amd64/asm.h
+++ b/sys/include/arch/amd64/asm.h
@@ -70,6 +70,18 @@ amd64_read_gs_base(void)
     return rdmsr(IA32_KERNEL_GS_BASE);
 }
 
+static inline void
+amd64_write_fs_base(uintptr_t val)
+{
+    wrmsr(IA32_FS_BASE, val);
+}
+
+static inline uintptr_t
+amd64_read_fs_base(uintptr_t val)
+{
+    return rdmsr(IA32_FS_BASE);
+}
+
 static inline uint64_t
 amd64_read_cr0(void)
 {
diff --git a/sys/include/arch/amd64/msr.h b/sys/include/arch/amd64/msr.h
index d3d0c9a..fe5814b 100644
--- a/sys/include/arch/amd64/msr.h
+++ b/sys/include/arch/amd64/msr.h
@@ -32,6 +32,7 @@
 
 #define IA32_SPEC_CTL       0x00000048
 #define IA32_KERNEL_GS_BASE 0xC0000102
+#define IA32_FS_BASE        0xC0000100
 #define IA32_APIC_BASE_MSR  0x0000001B
 
 #if !defined(__ASSEMBLER__)
-- 
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