[PATCH 2/2] s390/syscall: Keep syscall number in extra ptregs member

[Sven Schnelle <svens@linux.ibm.com>]

Move the syscall number from ptregs::int_code to another union member
called syscall_nr. This simplifies the code a bit.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
---
 arch/s390/include/asm/ptrace.h  |  2 +-
 arch/s390/include/asm/syscall.h |  8 +++++---
 arch/s390/kernel/ptrace.c       |  2 +-
 arch/s390/kernel/signal.c       | 12 +++++-------
 arch/s390/kernel/syscall.c      | 11 ++++-------
 5 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index f39b349da9a7..2edc85ddcba8 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -130,7 +130,7 @@ struct pt_regs {
 			unsigned long int_parm_long;
 		};
 		struct {
-			unsigned long __unused;
+			unsigned long syscall_nr;
 			unsigned long syscall_ret;
 		};
 		struct tpi_info tpi_info;
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 22b6ed20a9ae..abb0d4348912 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -14,13 +14,15 @@
 #include <linux/err.h>
 #include <asm/ptrace.h>
 
+#define SVC_LEN 2
 extern const sys_call_ptr_t sys_call_table[];
 
 static inline long syscall_get_nr(struct task_struct *task,
 				  struct pt_regs *regs)
 {
-	return test_pt_regs_flag(regs, PIF_SYSCALL) ?
-		(regs->int_code & 0xffff) : -1;
+	if (!test_pt_regs_flag(regs, PIF_SYSCALL))
+		return -1;
+	return regs->syscall_nr;
 }
 
 static inline void syscall_set_nr(struct task_struct *task,
@@ -32,7 +34,7 @@ static inline void syscall_set_nr(struct task_struct *task,
 	 * the target task is stopped for tracing on entering syscall, so
 	 * there is no need to have the same check syscall_get_nr() has.
 	 */
-	regs->int_code = (regs->int_code & ~0xffff) | (nr & 0xffff);
+	regs->syscall_nr = nr;
 }
 
 static inline void syscall_rollback(struct task_struct *task,
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 125ca4c4e30c..00e825d01504 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -349,7 +349,7 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
 			addr == offsetof(struct user, regs.gprs[2])) {
 			struct pt_regs *regs = task_pt_regs(child);
 
-			regs->int_code = 0x20000 | (data & 0xffff);
+			regs->syscall_nr = data;
 		}
 		*(addr_t *)((addr_t) &regs->psw + addr) = data;
 	} else if (addr < offsetof(struct user, regs.orig_gpr2)) {
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 4874de5edea0..c3c69294ff33 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -447,12 +447,12 @@ void arch_do_signal_or_restart(struct pt_regs *regs)
 	 * call information.
 	 */
 	current->thread.system_call =
-		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
+		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->syscall_nr : 0;
 
 	if (get_signal(&ksig)) {
 		/* Whee!  Actually deliver the signal.  */
 		if (current->thread.system_call) {
-			regs->int_code = current->thread.system_call;
+			regs->syscall_nr = current->thread.system_call;
 			/* Check for system call restarting. */
 			switch (regs->gprs[2]) {
 			case -ERESTART_RESTARTBLOCK:
@@ -467,9 +467,7 @@ void arch_do_signal_or_restart(struct pt_regs *regs)
 				fallthrough;
 			case -ERESTARTNOINTR:
 				regs->gprs[2] = regs->orig_gpr2;
-				regs->psw.addr =
-					__rewind_psw(regs->psw,
-						     regs->int_code >> 16);
+				regs->psw.addr = __rewind_psw(regs->psw, SVC_LEN);
 				break;
 			}
 		}
@@ -484,7 +482,7 @@ void arch_do_signal_or_restart(struct pt_regs *regs)
 	/* No handlers present - check for system call restart */
 	clear_pt_regs_flag(regs, PIF_SYSCALL);
 	if (current->thread.system_call) {
-		regs->int_code = current->thread.system_call;
+		regs->syscall_nr = current->thread.system_call;
 		switch (regs->gprs[2]) {
 		case -ERESTART_RESTARTBLOCK:
 			/* Restart with sys_restart_syscall */
@@ -498,7 +496,7 @@ void arch_do_signal_or_restart(struct pt_regs *regs)
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
 			regs->gprs[2] = regs->orig_gpr2;
-			regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
+			regs->psw.addr = __rewind_psw(regs->psw, SVC_LEN);
 			if (test_thread_flag(TIF_SINGLE_STEP))
 				clear_thread_flag(TIF_PER_TRAP);
 			break;
diff --git a/arch/s390/kernel/syscall.c b/arch/s390/kernel/syscall.c
index ce244dceec6d..62e283ffef37 100644
--- a/arch/s390/kernel/syscall.c
+++ b/arch/s390/kernel/syscall.c
@@ -100,7 +100,10 @@ void noinstr __do_syscall(struct pt_regs *regs, int per_trap)
 	enter_from_user_mode(regs);
 	add_random_kstack_offset();
 	regs->psw = get_lowcore()->svc_old_psw;
-	regs->int_code = get_lowcore()->svc_int_code;
+	nr = get_lowcore()->svc_int_code & 0xffff;
+	if (likely(!nr))
+		nr = regs->gprs[1];
+	regs->syscall_nr = nr;
 	update_timer_sys();
 	if (cpu_has_bear())
 		current->thread.last_break = regs->last_break;
@@ -110,12 +113,6 @@ void noinstr __do_syscall(struct pt_regs *regs, int per_trap)
 		set_thread_flag(TIF_PER_TRAP);
 	regs->flags = 0;
 	set_pt_regs_flag(regs, PIF_SYSCALL);
-	nr = regs->int_code & 0xffff;
-	if (likely(!nr)) {
-		nr = regs->gprs[1] & 0xffff;
-		regs->int_code &= ~0xffffUL;
-		regs->int_code |= nr;
-	}
 	regs->gprs[2] = nr;
 	regs->syscall_ret = -ENOSYS;
 	if (nr == __NR_restart_syscall && !(current->restart_block.arch_data & 1)) {
-- 
2.53.0