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Commit 5f6b5b97 authored by Paul Mackerras's avatar Paul Mackerras
Browse files

powerpc: Fix time setting bug on 32-bit 



This fixes a bug where settimeofday would set the wrong parameters
in do_gtod, resulting in gettimeofday returning a value about 4
hours after the correct time.  The bug was that we divided a
negative 64-bit value with do_div, which treated it as unsigned
and gave us a result that was approximately 1.8e10 too large
(since the divisor was 1e9).

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent eb66ce63

arch/powerpc/kernel/time.c

+8 −6
Original line number Original line Diff line number Diff line
@@ -518,7 +518,7 @@ int do_settimeofday(struct timespec *tv) 
	long wtm_nsec, new_nsec = tv->tv_nsec;

	long wtm_nsec, new_nsec = tv->tv_nsec;

	unsigned long flags;

	unsigned long flags;

	long int tb_delta;

	long int tb_delta;

	u64 new_xsec;

	u64 new_xsec, tb_delta_xs;





	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)

	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)

		return -EINVAL;

		return -EINVAL;
@@ -541,8 +541,7 @@ int do_settimeofday(struct timespec *tv) 
#endif

#endif

	tb_delta = tb_ticks_since(tb_last_stamp);

	tb_delta = tb_ticks_since(tb_last_stamp);

	tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;

	tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;



	tb_delta_xs = mulhdu(tb_delta, do_gtod.varp->tb_to_xs);

	new_nsec -= 1000 * mulhwu(tb_to_us, tb_delta);





	wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);

	wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);

	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);

	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
@@ -557,9 +556,12 @@ int do_settimeofday(struct timespec *tv) 




	ntp_clear();

	ntp_clear();





	new_xsec = 0;

	if (new_nsec != 0) {

		new_xsec = (u64)new_nsec * XSEC_PER_SEC;

		new_xsec = (u64)new_nsec * XSEC_PER_SEC;

		do_div(new_xsec, NSEC_PER_SEC);

		do_div(new_xsec, NSEC_PER_SEC);

	new_xsec += (u64)new_sec * XSEC_PER_SEC;

	}

	new_xsec += (u64)new_sec * XSEC_PER_SEC - tb_delta_xs;

	update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);

	update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);





#ifdef CONFIG_PPC64

#ifdef CONFIG_PPC64