Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h
new file mode 100644
index 0000000..bca4c74
--- /dev/null
+++ b/arch/x86/include/asm/fsgsbase.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_FSGSBASE_H
+#define _ASM_FSGSBASE_H
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_X86_64
+
+#include <asm/msr-index.h>
+
+/*
+ * Read/write a task's FSBASE or GSBASE. This returns the value that
+ * the FS/GS base would have (if the task were to be resumed). These
+ * work on the current task or on a non-running (typically stopped
+ * ptrace child) task.
+ */
+extern unsigned long x86_fsbase_read_task(struct task_struct *task);
+extern unsigned long x86_gsbase_read_task(struct task_struct *task);
+extern void x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase);
+extern void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase);
+
+/* Helper functions for reading/writing FS/GS base */
+
+static inline unsigned long x86_fsbase_read_cpu(void)
+{
+ unsigned long fsbase;
+
+ rdmsrl(MSR_FS_BASE, fsbase);
+
+ return fsbase;
+}
+
+static inline unsigned long x86_gsbase_read_cpu_inactive(void)
+{
+ unsigned long gsbase;
+
+ rdmsrl(MSR_KERNEL_GS_BASE, gsbase);
+
+ return gsbase;
+}
+
+static inline void x86_fsbase_write_cpu(unsigned long fsbase)
+{
+ wrmsrl(MSR_FS_BASE, fsbase);
+}
+
+static inline void x86_gsbase_write_cpu_inactive(unsigned long gsbase)
+{
+ wrmsrl(MSR_KERNEL_GS_BASE, gsbase);
+}
+
+#endif /* CONFIG_X86_64 */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_FSGSBASE_H */