s390/time: return with irqs disabled from psw_idle

Modify the psw_idle waiting logic in entry[64].S to return with
interrupts disabled. This avoids potential issues with udelay
and interrupt loops as interrupts are not reenabled after
clock comparator interrupts.

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

5 files changed, 4 insertions, 6 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 5ca70b4b72cb..cc30d1fb000c 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -886,13 +886,13 @@ cleanup_idle:
         stm     %r9,%r10,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__TIMER_IDLE_EXIT(%r2)
         # prepare return psw
-        n       %r8,BASED(cleanup_idle_wait)    # clear wait state bit
+        n       %r8,BASED(cleanup_idle_wait)    # clear irq & wait state bits
         l       %r9,24(%r11)                    # return from psw_idle
         br      %r14
 cleanup_idle_insn:
         .long   psw_idle_lpsw + 0x80000000
 cleanup_idle_wait:
-        .long   0xfffdffff
+        .long   0xfcfdffff
 
 /*
  * Integer constants
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 980c7aa1cc5c..2b2188b97c6a 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -929,7 +929,7 @@ cleanup_idle:
         stg     %r9,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__TIMER_IDLE_EXIT(%r2)
         # prepare return psw
-        nihh    %r8,0xfffd              # clear wait state bit
+        nihh    %r8,0xfcfd              # clear irq & wait state bits
         lg      %r9,48(%r11)            # return from psw_idle
         br      %r14
 cleanup_idle_insn:
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 2bc3eddae34a..c5dbb335716d 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -71,6 +71,7 @@ void arch_cpu_idle(void)
         }
         /* Halt the cpu and keep track of cpu time accounting. */
         vtime_stop_cpu();
+        local_irq_enable();
 }
 
 void arch_cpu_idle_exit(void)
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 876546b9cfa1..064c3082ab33 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -92,7 +92,6 @@ void clock_comparator_work(void)
         struct clock_event_device *cd;
 
         S390_lowcore.clock_comparator = -1ULL;
-        set_clock_comparator(S390_lowcore.clock_comparator);
         cd = &__get_cpu_var(comparators);
         cd->event_handler(cd);
 }
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index c61b9fad43cc..57c87d7d7ede 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -44,7 +44,6 @@ static void __udelay_disabled(unsigned long long usecs)
         do {
                 set_clock_comparator(end);
                 vtime_stop_cpu();
-                local_irq_disable();
         } while (get_tod_clock() < end);
         lockdep_on();
         __ctl_load(cr0, 0, 0);
@@ -64,7 +63,6 @@ static void __udelay_enabled(unsigned long long usecs)
                         set_clock_comparator(end);
                 }
                 vtime_stop_cpu();
-                local_irq_disable();
                 if (clock_saved)
                         local_tick_enable(clock_saved);
         } while (get_tod_clock() < end);