On Wed, Jul 10, 2019 at 03:01:53PM +0200, Arnd Bergmann wrote:
On 32-bit x86 when building with clang-9, the loop gets turned back into an inefficient division that causes a link error:
kernel/time/vsyscall.o: In function `update_vsyscall': vsyscall.c:(.text+0xe3): undefined reference to `__udivdi3'
Use the provided __iter_div_u64_rem() function that is meant to address the same case in other files.
Fixes: 44f57d788e7d ("timekeeping: Provide a generic update_vsyscall() implementation") Signed-off-by: Arnd Bergmann arnd@arndb.de
kernel/time/vsyscall.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c index a80893180826..8cf3596a4ce6 100644 --- a/kernel/time/vsyscall.c +++ b/kernel/time/vsyscall.c @@ -104,11 +104,7 @@ void update_vsyscall(struct timekeeper *tk) vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; nsec = nsec + tk->wall_to_monotonic.tv_nsec;
- while (nsec >= NSEC_PER_SEC) {
nsec = nsec - NSEC_PER_SEC;vdso_ts->sec++;- }
- vdso_ts->nsec = nsec;
- vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
if (__arch_use_vsyscall(vdata)) update_vdso_data(vdata, tk); -- 2.20.0
What an interesting function. Looks good to me and I can confirm it fixes the link error.
Reviewed-by: Nathan Chancellor natechancellor@gmail.com Tested-by: Nathan Chancellor natechancellor@gmail.com