| Message ID | 1359634539-9580-12-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 31, 2013 at 12:15:34PM +0000, Mark Rutland wrote: > 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>
diff --git a/arch/arm64/include/asm/arm_generic.h b/arch/arm64/include/asm/arm_generic.h index df2aeb8..6ece2f1 100644 --- a/arch/arm64/include/asm/arm_generic.h +++ b/arch/arm64/include/asm/arm_generic.h @@ -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;
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> --- arch/arm64/include/asm/arm_generic.h | 2 ++ 1 file changed, 2 insertions(+)