--- /dev/null
+#ifndef _X86_64_CURRENT_H
+#define _X86_64_CURRENT_H
+
+#if !defined(__ASSEMBLY__)
+struct task_struct;
+
+#include <arch/pda.h>
+
+/**
+ * In normal operation, the current task pointer is read directly from
+ * the PDA.
+ *
+ * If the PDA has not been setup or is not available for some reason,
+ * the slower get_current_via_RSP() must be used instead. This is
+ * sometimes necessary during the bootstrap process.
+ */
+static inline struct task_struct *
+get_current(void)
+{
+ struct task_struct *t = read_pda(pcurrent);
+ return t;
+}
+#define current get_current()
+
+/**
+ * Derives the current task pointer from the current value of the
+ * stack pointer (RSP register).
+ *
+ * WARNING: Do not call this from interrupt context. It won't work.
+ * It is only safe to call this from task context.
+ */
+static inline struct task_struct *
+get_current_via_RSP(void)
+{
+ struct task_struct *tsk;
+ __asm__("andq %%rsp,%0; " : "=r" (tsk) : "0" (~(TASK_SIZE - 1)));
+ return tsk;
+}
+
+#else
+
+#ifndef ASM_OFFSET_H
+#include <arch/asm-offsets.h>
+#endif
+
+#define GET_CURRENT(reg) movq %gs:(pda_pcurrent),reg
+
+#endif
+
+#endif /* !(_X86_64_CURRENT_H) */
