arm64: percpu: Make this_cpu accessors pre-empt safe

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this_cpu operations were implemented for arm64 in:
 5284e1b arm64: xchg: Implement cmpxchg_double
 f97fc81 arm64: percpu: Implement this_cpu operations

Unfortunately, it is possible for pre-emption to take place between
address generation and data access. This can lead to cases where data
is being manipulated by this_cpu for a different CPU than it was
called on. Which effectively breaks the spec.

This patch disables pre-emption for the this_cpu operations
guaranteeing that address generation and data manipulation take place
without a pre-emption in-between.

Fixes: 5284e1b4bc ("arm64: xchg: Implement cmpxchg_double")
Fixes: f97fc81079 ("arm64: percpu: Implement this_cpu operations")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Steve Capper <steve.capper@linaro.org>
[catalin.marinas@arm.com: remove space after type cast]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

...

This commit is contained in:

Steve Capper 2015-03-22 14:51:51 +00:00 • committed by Catalin Marinas

parent e53f21bce4

commit f3eab7184d

2 changed files with 57 additions and 19 deletions

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30

arch/arm64/include/asm/cmpxchg.h

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46

arch/arm64/include/asm/percpu.h

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