2 files changed, 6 insertions, 1 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c3429e8b2424..c9786480f0fe 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -1000,7 +1000,7 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk);
 #define thread_saved_pc(t)      (*(unsigned long *)((t)->thread.sp - 8))
 
 #define task_pt_regs(tsk)       ((struct pt_regs *)(tsk)->thread.sp0 - 1)
-#define KSTK_ESP(tsk)           -1 /* sorry. doesn't work for syscall. */
+extern unsigned long KSTK_ESP(struct task_struct *task);
 #endif /* CONFIG_X86_64 */
 
 extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ad535b683170..eb62cbcaa490 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -664,3 +664,8 @@ long sys_arch_prctl(int code, unsigned long addr)
         return do_arch_prctl(current, code, addr);
 }
 
+unsigned long KSTK_ESP(struct task_struct *task)
+{
+        return (test_tsk_thread_flag(task, TIF_IA32)) ?
+                        (task_pt_regs(task)->sp) : ((task)->thread.usersp);
+}