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arm64: arm_generic: prevent reading stale time

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Currently arch_counter_get_cnt{p,v}ct can be speculated, allowing for
stale time values to be read. This could be problematic for the delay
loop and other sensitive functions, as the time delta could jump around
unexpectedly.

This patch adds isbs to arch_counter_get_cnt{p,v}ct, preventing this
possibility.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2013-01-15 11:12:29 +00:00
parent 8a4da6e36c
commit 1dac0dd71c
1 changed files with 2 additions and 0 deletions
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2
arch/arm64/include/asm/arm_generic.h
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@ -83,6 +83,7 @@ static inline cycle_t arch_counter_get_cntpct(void)
{
cycle_t cval;
isb();
asm volatile("mrs %0, cntpct_el0" : "=r" (cval));
return cval;
@ -92,6 +93,7 @@ static inline cycle_t arch_counter_get_cntvct(void)
{
cycle_t cval;
isb();
asm volatile("mrs %0, cntvct_el0" : "=r" (cval));
return cval;