time: Add y2038 safe read_persistent_clock64()

As part of addressing in-kernel y2038 issues, this patch adds
read_persistent_clock64() and replaces all the call sites of
read_persistent_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
read_persistent_clock().

This allows architecture specific implementations to be
converted independently, and eventually the y2038 unsafe
read_persistent_clock() can be removed after all its
architecture specific implementations have been converted to
read_persistent_clock64().

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 12 insertions, 10 deletions

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 652e50a9c6ed..b1dbfa573dce 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1173,6 +1173,14 @@ void __weak read_persistent_clock(struct timespec *ts)
         ts->tv_nsec = 0;
 }
 
+void __weak read_persistent_clock64(struct timespec64 *ts64)
+{
+        struct timespec ts;
+
+        read_persistent_clock(&ts);
+        *ts64 = timespec_to_timespec64(ts);
+}
+
 /**
  * read_boot_clock -  Return time of the system start.
  *
@@ -1205,10 +1213,8 @@ void __init timekeeping_init(void)
         struct clocksource *clock;
         unsigned long flags;
         struct timespec64 now, boot, tmp;
-        struct timespec ts;
 
-        read_persistent_clock(&ts);
-        now = timespec_to_timespec64(ts);
+        read_persistent_clock64(&now);
         if (!timespec64_valid_strict(&now)) {
                 pr_warn("WARNING: Persistent clock returned invalid value!\n"
                         "         Check your CMOS/BIOS settings.\n");
@@ -1278,7 +1284,7 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
  * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
  * @delta: pointer to a timespec64 delta value
  *
- * This hook is for architectures that cannot support read_persistent_clock
+ * This hook is for architectures that cannot support read_persistent_clock64
  * because their RTC/persistent clock is only accessible when irqs are enabled.
  *
  * This function should only be called by rtc_resume(), and allows
@@ -1325,12 +1331,10 @@ void timekeeping_resume(void)
         struct clocksource *clock = tk->tkr_mono.clock;
         unsigned long flags;
         struct timespec64 ts_new, ts_delta;
-        struct timespec tmp;
         cycle_t cycle_now, cycle_delta;
         bool suspendtime_found = false;
 
-        read_persistent_clock(&tmp);
-        ts_new = timespec_to_timespec64(tmp);
+        read_persistent_clock64(&ts_new);
 
         clockevents_resume();
         clocksource_resume();
@@ -1406,10 +1410,8 @@ int timekeeping_suspend(void)
         unsigned long flags;
         struct timespec64               delta, delta_delta;
         static struct timespec64        old_delta;
-        struct timespec tmp;
 
-        read_persistent_clock(&tmp);
-        timekeeping_suspend_time = timespec_to_timespec64(tmp);
+        read_persistent_clock64(&timekeeping_suspend_time);
 
         /*
          * On some systems the persistent_clock can not be detected at