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Will Deacon dbb236c1ce arm64/vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW 
Recently vDSO support for CLOCK_MONOTONIC_RAW was added in
49eea433b3 ("arm64: Add support for CLOCK_MONOTONIC_RAW in
clock_gettime() vDSO"). Noticing that the core timekeeping code
never set tkr_raw.xtime_nsec, the vDSO implementation didn't
bother exposing it via the data page and instead took the
unshifted tk->raw_time.tv_nsec value which was then immediately
shifted left in the vDSO code.

Unfortunately, by accellerating the MONOTONIC_RAW clockid, it
uncovered potential 1ns time inconsistencies caused by the
timekeeping core not handing sub-ns resolution.

Now that the core code has been fixed and is actually setting
tkr_raw.xtime_nsec, we need to take that into account in the
vDSO by adding it to the shifted raw_time value, in order to
fix the user-visible inconsistency. Rather than do that at each
use (and expand the data page in the process), instead perform
the shift/addition operation when populating the data page and
remove the shift from the vDSO code entirely.

[jstultz: minor whitespace tweak, tried to improve commit
 message to make it more clear this fixes a regression]
Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Daniel Mentz <danielmentz@google.com>
Acked-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Cc: "stable #4 . 8+" <stable@vger.kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Link: http://lkml.kernel.org/r/1496965462-20003-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 		2017-06-20 10:41:51 +02:00
..
.gitignore arm64: drop non-existing vdso-offsets.h from .gitignore 2017-03-30 19:29:30 +01:00
Makefile arm64: fix vdso-offsets.h dependency 2016-07-11 17:10:11 +01:00
gen_vdso_offsets.sh arm64: VDSO support 2012-09-17 13:42:09 +01:00
gettimeofday.S arm64/vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW 2017-06-20 10:41:51 +02:00
note.S arm64: VDSO support 2012-09-17 13:42:09 +01:00
sigreturn.S arm64: VDSO support 2012-09-17 13:42:09 +01:00
vdso.S arm64: vdso: Mark vDSO code as read-only 2016-02-16 18:20:23 +00:00
vdso.lds.S arm64: vdso: move data page before code pages 2014-07-17 16:18:57 +01:00