s390: move system_call field from thread_info to thread_struct

The system_call field in thread_info structure is used by the signal
code to store the number of the current system call while the debugger
interacts with its inferior. A better location for the system_call
field is with the other debugger related information in the
thread_struct.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/processor.h

@@ -115,9 +115,11 @@ struct thread_struct {
 	unsigned int gmap_write_flag;	/* gmap fault write indication */
 	unsigned int gmap_int_code;	/* int code of last gmap fault */
 	unsigned int gmap_pfault;	/* signal of a pending guest pfault */
+	/* Per-thread information related to debugging */
 	struct per_regs per_user;	/* User specified PER registers */
 	struct per_event per_event;	/* Cause of the last PER trap */
 	unsigned long per_flags;	/* Flags to control debug behavior */
+	unsigned int system_call;	/* system call number in signal */
         /* pfault_wait is used to block the process on a pfault event */
 	unsigned long pfault_wait;
 	struct list_head list;

arch/s390/include/asm/thread_info.h

@@ -32,7 +32,6 @@
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	unsigned long		sys_call_table;	/* System call table address */
-	unsigned int		system_call;
 	__u64			user_timer;
 	__u64			system_timer;
 	unsigned long		last_break;	/* last breaking-event-address. */

arch/s390/kernel/ptrace.c

@@ -1113,7 +1113,7 @@ static int s390_system_call_get(struct task_struct *target,
 				unsigned int pos, unsigned int count,
 				void *kbuf, void __user *ubuf)
 {
-	unsigned int *data = &task_thread_info(target)->system_call;
+	unsigned int *data = &target->thread.system_call;
 	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 				   data, 0, sizeof(unsigned int));
 }
@@ -1123,7 +1123,7 @@ static int s390_system_call_set(struct task_struct *target,
 				unsigned int pos, unsigned int count,
 				const void *kbuf, const void __user *ubuf)
 {
-	unsigned int *data = &task_thread_info(target)->system_call;
+	unsigned int *data = &target->thread.system_call;
 	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 				  data, 0, sizeof(unsigned int));
 }

arch/s390/kernel/signal.c

@@ -467,13 +467,13 @@ void do_signal(struct pt_regs *regs)
 	 * the debugger may change all our registers, including the system
 	 * call information.
 	 */
-	current_thread_info()->system_call =
+	current->thread.system_call =
 		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
 
 	if (get_signal(&ksig)) {
 		/* Whee!  Actually deliver the signal.  */
-		if (current_thread_info()->system_call) {
-			regs->int_code = current_thread_info()->system_call;
+		if (current->thread.system_call) {
+			regs->int_code = current->thread.system_call;
 			/* Check for system call restarting. */
 			switch (regs->gprs[2]) {
 			case -ERESTART_RESTARTBLOCK:
@@ -506,8 +506,8 @@ void do_signal(struct pt_regs *regs)
 
 	/* No handlers present - check for system call restart */
 	clear_pt_regs_flag(regs, PIF_SYSCALL);
-	if (current_thread_info()->system_call) {
-		regs->int_code = current_thread_info()->system_call;
+	if (current->thread.system_call) {
+		regs->int_code = current->thread.system_call;
 		switch (regs->gprs[2]) {
 		case -ERESTART_RESTARTBLOCK:
 			/* Restart with sys_restart_syscall */