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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>
This commit is contained in:
Will Deacon 2012-11-30 18:34:25 +00:00 committed by Catalin Marinas
parent f2bd5d2406
commit 251db45336
1 changed files with 1 additions and 1 deletions
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2
arch/arm64/kernel/vdso/gettimeofday.S
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@ -223,7 +223,7 @@ ENTRY(__do_get_tspec)
/* Calculate cycle delta and convert to ns. */
sub x10, x9, x10
/* We can only guarantee 56 bits of precision. */
movn x9, #0xff0, lsl #48
movn x9, #0xff00, lsl #48
and x10, x9, x10
mul x10, x10, x14
lsr x10, x10, x15