[S390] add TIF_SYSCALL thread flag

Add an explicit TIF_SYSCALL bit that indicates if a task is inside
a system call. The svc_code in the pt_regs structure is now only
valid if TIF_SYSCALL is set. With this definition TIF_RESTART_SVC
can be replaced with TIF_SYSCALL. Overall do_signal is a bit more
readable and it saves a few lines of code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 4 insertions, 3 deletions

diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 614267f60713..b239ff53b189 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -26,7 +26,8 @@ extern const unsigned int sys_call_table[];
 static inline long syscall_get_nr(struct task_struct *task,
                                   struct pt_regs *regs)
 {
-        return regs->svc_code ? (regs->svc_code & 0xffff) : -1;
+        return test_tsk_thread_flag(task, TIF_SYSCALL) ?
+                (regs->svc_code & 0xffff) : -1;
 }
 
 static inline void syscall_rollback(struct task_struct *task,
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 0c4788eb5a65..a23183423b14 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -85,10 +85,10 @@ static inline struct thread_info *current_thread_info(void)
 /*
  * thread information flags bit numbers
  */
+#define TIF_SYSCALL             0       /* inside a system call */
 #define TIF_NOTIFY_RESUME       1       /* callback before returning to user */
 #define TIF_SIGPENDING          2       /* signal pending */
 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
-#define TIF_RESTART_SVC         4       /* restart svc with new svc number */
 #define TIF_PER_TRAP            6       /* deliver sigtrap on return to user */
 #define TIF_MCCK_PENDING        7       /* machine check handling is pending */
 #define TIF_SYSCALL_TRACE       8       /* syscall trace active */
@@ -104,11 +104,11 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SINGLE_STEP         20      /* This task is single stepped */
 #define TIF_FREEZE              21      /* thread is freezing for suspend */
 
+#define _TIF_SYSCALL            (1<<TIF_SYSCALL)
 #define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
 #define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED       (1<<TIF_NEED_RESCHED)
-#define _TIF_RESTART_SVC        (1<<TIF_RESTART_SVC)
 #define _TIF_PER_TRAP           (1<<TIF_PER_TRAP)
 #define _TIF_MCCK_PENDING       (1<<TIF_MCCK_PENDING)
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)