diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c3429e8..c978648 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -1000,7 +1000,7 @@
 #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 ad535b6..eb62cbc 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -664,3 +664,8 @@
 	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);
+}
diff --git a/fs/compat.c b/fs/compat.c
index d576b55..6c19040 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1532,6 +1532,8 @@
 	if (retval < 0)
 		goto out;
 
+	current->stack_start = current->mm->start_stack;
+
 	/* execve succeeded */
 	current->fs->in_exec = 0;
 	current->in_execve = 0;