Commit Graph

7 Commits

Author SHA1 Message Date
Will Deacon bdba0051eb arm64: vdso: remove broken, redundant sequence counting for timezones
This patch is an arm64 version of ce73ec6db4 ("powerpc/vdso: Remove
redundant locking in update_vsyscall_tz()").

Timezone data is not protected, so the sequence counter is not required
to ensure consistency. Furthermore, having multiple paths updating the
counter leads to a race between update_vsyscall and update_vsyscall_tz,
so remove the timezone sequence counting from both the kernel and the
vdso.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-01-10 10:43:43 +00:00
Will Deacon 1f75ff0a3d arm64: generic timer: use virtual counter instead of physical at EL0
We want to use the virtual counter at EL0, as the physical counter
may not track the current clocksource for guests running under a
hypervisor.

This patch updates the vdso and generic timer driver to use the virtual
counter. The kernel EL2 entry code is also updated to ensure that the
virtual offset is initialised to zero.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-12-05 11:20:04 +00:00
Will Deacon 45a7905fc4 arm64: vdso: defer shifting of nanosecond component of timespec
Shifting the nanosecond component of the computed timespec early can
lead to sub-ns inaccuracies when using the truncated value as input to
further arithmetic for things like conversions to monotonic time.

This patch defers the timespec shifting until after the final value has
been computed.

Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-12-05 11:20:03 +00:00
Will Deacon d91fb5c267 arm64: vdso: rework __do_get_tspec register allocation and return shift
In preparation for sub-ns precision in the vdso timespec maths, change
the __do_get_tspec register allocation so that we return the clocksource
shift value instead of the unused xtime tspec.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-12-05 11:20:03 +00:00
Will Deacon f84a935db4 arm64: vdso: check sequence counter even for coarse realtime operations
When returning coarse realtime values from clock_gettime, we must still
check the sequence counter to ensure that the kernel does not update
the vdso datapage whilst we are loading the coarse timespec as this
could potentially result in time appearing to go backwards.

This patch delays the coarse realtime check until after we have loaded
successfully from the vdso datapage. This does mean that we always load
the wtm timespec, but conditionalising the load and adding an extra
sequence test is unlikely to buy us anything other than messy code,
particularly as the sequence test implies a read barrier.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-12-05 11:20:03 +00:00
Will Deacon 251db45336 arm64: vdso: fix clocksource mask when extracting bottom 56 bits
The generic timer clocksource has 56 bits of precision and as such must
be masked appropriately after we have read it. The current mask
generated by a movn instruction is off by 4 bits, so we accidentally
include the top 4 bits in the final value.

This patch fixes the broken mask.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-12-05 11:20:03 +00:00
Will Deacon 9031fefde6 arm64: VDSO support
This patch adds VDSO support for 64-bit applications. The VDSO code is
currently used for sys_rt_sigreturn() and optimised gettimeofday()
(using the user-accessible generic counter).

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-09-17 13:42:09 +01:00