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author | Will Deacon <will.deacon@arm.com> | 2017-06-09 02:44:22 +0300 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2017-06-20 11:41:51 +0300 |
commit | dbb236c1ceb697a559e0694ac4c9e7b9131d0b16 (patch) | |
tree | 171280b1a599f77933532dda1695f07074b9342f /arch/hexagon | |
parent | 3d88d56c5873f6eebe23e05c3da701960146b801 (diff) | |
download | linux-dbb236c1ceb697a559e0694ac4c9e7b9131d0b16.tar.xz |
arm64/vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW
Recently vDSO support for CLOCK_MONOTONIC_RAW was added in
49eea433b326 ("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>
Diffstat (limited to 'arch/hexagon')
0 files changed, 0 insertions, 0 deletions