diff options
| author | John Stultz <johnstul@us.ibm.com> | 2010-08-13 11:30:58 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-26 16:46:18 -0700 |
| commit | 59ea469c637e35604a6989a933b33883b1fcb0ab (patch) | |
| tree | de465f60456e9e7bff8900e54d4eaa82a816627a | |
| parent | 0d3a7582aa527a5d0107039d24571faa57114bff (diff) | |
time: Workaround gcc loop optimization that causes 64bit div errors
commit c7dcf87a6881bf796faee83003163eb3de41a309 upstream.
Early 4.3 versions of gcc apparently aggressively optimize the raw
time accumulation loop, replacing it with a divide.
On 32bit systems, this causes the following link errors:
undefined reference to `__umoddi3'
undefined reference to `__udivdi3'
The gcc issue has been fixed in 4.4 and greater.
This patch replaces the accumulation loop with a do_div, as suggested
by Linus.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
CC: Jason Wessel <jason.wessel@windriver.com>
CC: Larry Finger <Larry.Finger@lwfinger.net>
CC: Ingo Molnar <mingo@elte.hu>
CC: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | kernel/time/timekeeping.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 66038608cb30..b87c22f5faf9 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -756,9 +756,10 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift) /* Accumulate raw time */ raw_nsecs = timekeeper.raw_interval << shift; raw_nsecs += raw_time.tv_nsec; - while (raw_nsecs >= NSEC_PER_SEC) { - raw_nsecs -= NSEC_PER_SEC; - raw_time.tv_sec++; + if (raw_nsecs >= NSEC_PER_SEC) { + u64 raw_secs = raw_nsecs; + raw_nsecs = do_div(raw_secs, NSEC_PER_SEC); + raw_time.tv_sec += raw_secs; } raw_time.tv_nsec = raw_nsecs; |