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* arm64: vdso: remove broken, redundant sequence counting for timezonesWill Deacon2013-01-101-2/+0
| | | | | | | | | | | | | | This patch is an arm64 version of ce73ec6db47a ("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>
* arm64: generic timer: use virtual counter instead of physical at EL0Will Deacon2012-12-051-2/+2
| | | | | | | | | | | | | | 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>
* arm64: vdso: defer shifting of nanosecond component of timespecWill Deacon2012-12-051-2/+6
| | | | | | | | | | | | | 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>
* arm64: vdso: rework __do_get_tspec register allocation and return shiftWill Deacon2012-12-051-44/+44
| | | | | | | | | 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>
* arm64: vdso: check sequence counter even for coarse realtime operationsWill Deacon2012-12-051-3/+3
| | | | | | | | | | | | | | | | 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>
* arm64: vdso: fix clocksource mask when extracting bottom 56 bitsWill Deacon2012-12-051-1/+1
| | | | | | | | | | | | | 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>
* arm64: VDSO supportWill Deacon2012-09-178-0/+520
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>
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