Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 14ecafa9 authored by Maria Yu's avatar Maria Yu
Browse files

Revert "clocksource: arch_timer: make virtual counter access configurable" 



This reverts commit dc9b4c45.
Disable userspace virtual counter access intended to makes it
difficult to obtain precise timing measurements of the cache
side channel. But it has been deprecated since it was found
to be ineffective.

Change-Id: I5cf59632ff1beb6ea51a53bea4eb3ad9467d4cd0
Signed-off-by: default avatarMaria Yu <aiquny@codeaurora.org>
parent a9eb6ca4

drivers/clocksource/Kconfig

+0 −8
Original line number Diff line number Diff line
@@ -385,14 +385,6 @@ config SUN50I_ERRATUM_UNKNOWN1 
	  the Allwinner A64 SoC. The workaround will only be active if the

	  allwinner,erratum-unknown1 property is found in the timer node.



config ARM_ARCH_TIMER_VCT_ACCESS

	bool "Support for ARM architected timer virtual counter access in userspace"

	default n

	depends on ARM_ARCH_TIMER

	help

	  This option enables support for reading the ARM architected timer's

	  virtual counter in userspace.



config ARM_GLOBAL_TIMER

	bool "Support for the ARM global timer" if COMPILE_TEST

	select TIMER_OF if OF

drivers/clocksource/arm_arch_timer.c

+1 −2
Original line number Diff line number Diff line
@@ -863,8 +863,7 @@ static void arch_counter_set_user_access(void) 
	 * need to be workaround. The vdso may have been already

	 * disabled though.

	 */

	if (arch_timer_this_cpu_has_cntvct_wa() ||

	    !IS_ENABLED(CONFIG_ARM_ARCH_TIMER_VCT_ACCESS))

	if (arch_timer_this_cpu_has_cntvct_wa())

		pr_info("CPU%d: Trapping CNTVCT access\n", smp_processor_id());

	else

		cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;