s390: convert to generic entry

This patch converts s390 to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on s390:

- PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't
  know about our PIF flags in exit_to_user_mode_loop().

- The old code had several ways to restart syscalls:

  a) PIF_SYSCALL_RESTART, which was only set during execve to force a
     restart after upgrading a process (usually qemu-kvm) to pgste page
     table extensions.

  b) PIF_SYSCALL, which is set by do_signal() to indicate that the
     current syscall should be restarted. This is changed so that
     do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use
     PIF_SYSCALL doesn't work with the generic code, and changing it
     to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART
     more unique.

- On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by
executing a svc instruction on the process stack which causes a fault.
While handling that fault the fault code sets PIF_SYSCALL to hand over
processing to the syscall code on exit to usermode.

The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets
a return value for a syscall. The s390x ptrace ABI uses r2 both for the
syscall number and return value, so ptrace cannot set the syscall number +
return value at the same time. The flag makes handling that a bit easier.
do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET
is set.

CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY.
CR1/7/13 will be checked both on kernel entry and exit to contain the
correct asces.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/s390/kernel/idle.c b/arch/s390/kernel/idle.c
index a5d4d80d6ede..812073ea073e 100644
--- a/arch/s390/kernel/idle.c
+++ b/arch/s390/kernel/idle.c
@@ -14,12 +14,36 @@
 #include <linux/cpu.h>
 #include <linux/sched/cputime.h>
 #include <trace/events/power.h>
+#include <asm/cpu_mf.h>
 #include <asm/nmi.h>
 #include <asm/smp.h>
 #include "entry.h"
 
 static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
 
+void account_idle_time_irq(void)
+{
+	struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
+	u64 cycles_new[8];
+	int i;
+
+	clear_cpu_flag(CIF_ENABLED_WAIT);
+	if (smp_cpu_mtid) {
+		stcctm(MT_DIAG, smp_cpu_mtid, cycles_new);
+		for (i = 0; i < smp_cpu_mtid; i++)
+			this_cpu_add(mt_cycles[i], cycles_new[i] - idle->mt_cycles_enter[i]);
+	}
+
+	idle->clock_idle_exit = S390_lowcore.int_clock;
+	idle->timer_idle_exit = S390_lowcore.sys_enter_timer;
+
+	S390_lowcore.steal_timer += idle->clock_idle_enter - S390_lowcore.last_update_clock;
+	S390_lowcore.last_update_clock = idle->clock_idle_exit;
+
+	S390_lowcore.system_timer += S390_lowcore.last_update_timer - idle->timer_idle_enter;
+	S390_lowcore.last_update_timer = idle->timer_idle_exit;
+}
+
 void arch_cpu_idle(void)
 {
 	struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);