linux/arch/arm64
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
..
boot ARM: SoC fixes 2017-06-19 16:50:09 +08:00
configs arm64: defconfig: enable some core options for 64bit Rockchip socs 2017-05-25 17:01:35 -07:00
crypto Revert "crypto: arm64/sha - Add constant operand modifier to ASM_EXPORT" 2017-04-24 16:09:50 +08:00
include KVM/ARM Fixes for v4.12-rc5 - Take 2 2017-06-08 15:04:38 +02:00
kernel arm64/vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW 2017-06-20 10:41:51 +02:00
kvm arm64: KVM: Allow unaligned accesses at EL2 2017-06-06 22:20:02 +02:00
lib arm64: switch to RAW_COPY_USER 2017-03-28 18:23:24 -04:00
mm IOMMU Updates for Linux v4.12 2017-05-09 15:15:47 -07:00
net bpf, arm64: use separate register for state in stxr 2017-06-07 15:27:20 -04:00
xen xen/privcmd: Add IOCTL_PRIVCMD_DM_OP 2017-02-14 15:13:43 -05:00
Kconfig security/keys: add CONFIG_KEYS_COMPAT to Kconfig 2017-06-09 13:29:45 +10:00
Kconfig.debug arm64: relocation testing module 2017-04-04 17:03:32 +01:00
Kconfig.platforms mvebu arm64 for 4.12 2017-05-10 15:36:43 +02:00
Makefile Kbuild misc updates for 4.12 2017-05-10 20:41:43 -07:00