powerpc: Avoid giving out RTC dates below EPOCH

Doing so causes xtime to be negative which crashes the timekeeping
code in funny ways when doing suspend/resume

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 92dc844299b6..a136a11c490d 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -777,7 +777,7 @@ int update_persistent_clock(struct timespec now)
         return ppc_md.set_rtc_time(&tm);
 }
 
-void read_persistent_clock(struct timespec *ts)
+static void __read_persistent_clock(struct timespec *ts)
 {
         struct rtc_time tm;
         static int first = 1;
@@ -800,10 +800,23 @@ void read_persistent_clock(struct timespec *ts)
                 return;
         }
         ppc_md.get_rtc_time(&tm);
+
         ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
                             tm.tm_hour, tm.tm_min, tm.tm_sec);
 }
 
+void read_persistent_clock(struct timespec *ts)
+{
+        __read_persistent_clock(ts);
+
+        /* Sanitize it in case real time clock is set below EPOCH */
+        if (ts->tv_sec < 0) {
+                ts->tv_sec = 0;
+                ts->tv_nsec = 0;
+        }
+                
+}
+
 /* clocksource code */
 static cycle_t rtc_read(struct clocksource *cs)
 {