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| author | John Stultz <johnstul@us.ibm.com> | 2010-08-13 11:30:58 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-13 12:03:24 -0700 |
| commit | c7dcf87a6881bf796faee83003163eb3de41a309 (patch) | |
| tree | 1e4333e588ad6e8e69e310d8ae71798af1c0bdb5 /kernel/time | |
| parent | 2be1f3a73dd02e38e181cf5abacb3d45a6a2d6b8 (diff) | |
| download | linux-c7dcf87a6881bf796faee83003163eb3de41a309.tar.gz linux-c7dcf87a6881bf796faee83003163eb3de41a309.tar.bz2 linux-c7dcf87a6881bf796faee83003163eb3de41a309.zip | |
time: Workaround gcc loop optimization that causes 64bit div errors
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>
Diffstat (limited to 'kernel/time')
| -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 e960d824263f..49010d822f72 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -710,9 +710,10 @@ 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; |