Commit 381c02a7 authored by Yang Yingliang's avatar Yang Yingliang
Browse files

arm64: arch_timer: Disable CNTVCT_EL0 trap if workaround is enabled 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LFBU


CVE: NA

--------------------------------------------------

It costs very much time to read CNTVCT_EL0, if a cntvct workaround
and CNTVCT_EL0 trap is enabled. To decrease the read time, we disable
CNTVCT_EL0 trap, introduce vdso_fix and vdso_shift for doing cntvct
workaround in VDSO.

Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
parent cb2566ed

drivers/clocksource/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -732,4 +732,9 @@ config GOLDFISH_TIMER 
	help

	  Support for the timer/counter of goldfish-rtc



config ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	bool "Enable arch timer workaround in vdso"

	default y

	depends on ARM_ARCH_TIMER_OOL_WORKAROUND



endmenu

drivers/clocksource/arm_arch_timer.c

+27 −0
Original line number Diff line number Diff line
@@ -92,6 +92,10 @@ static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_ARCHTIMER; 
#else

static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_NONE;

#endif /* CONFIG_GENERIC_GETTIMEOFDAY */

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

static bool vdso_fix;

static u16 vdso_shift;

#endif



static cpumask_t evtstrm_available = CPU_MASK_NONE;

static bool evtstrm_enable __ro_after_init = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
@@ -599,8 +603,23 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa 
	 * change both the default value and the vdso itself.

	 */

	if (wa->read_cntvct_el0) {

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

		if (!strncmp(wa->desc, "HiSilicon erratum 161010101",

			     strlen("HiSilicon erratum 161010101"))) {

			vdso_fix = true;

			vdso_shift = 5;

		} else if (!strncmp(wa->desc, "Freescale erratum a005858",

				    strlen("Freescale erratum a005858"))) {

			vdso_fix = true;

			vdso_shift = 0;

		} else {

			clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;

			vdso_default = VDSO_CLOCKMODE_NONE;

		}

#else

		clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;

		vdso_default = VDSO_CLOCKMODE_NONE;

#endif

	} else if (wa->disable_compat_vdso && vdso_default != VDSO_CLOCKMODE_NONE) {

		vdso_default = VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT;

		clocksource_counter.vdso_clock_mode = vdso_default;
@@ -973,7 +992,11 @@ static void arch_counter_set_user_access(void) 
	 * need to be workaround. The vdso may have been already

	 * disabled though.

	 */

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	if (arch_timer_this_cpu_has_cntvct_wa() && !vdso_fix)

#else

	if (arch_timer_this_cpu_has_cntvct_wa())

#endif

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

	else

		cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
@@ -1129,6 +1152,10 @@ static void __init arch_counter_register(unsigned type) 


		arch_timer_read_counter = rd;

		clocksource_counter.vdso_clock_mode = vdso_default;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

		clocksource_counter.vdso_fix = vdso_fix;

		clocksource_counter.vdso_shift = vdso_shift;

#endif

	} else {

		arch_timer_read_counter = arch_counter_get_cntvct_mem;

		scr = arch_counter_get_cntvct_mem;

include/linux/clocksource.h

+4 −0
Original line number Diff line number Diff line
@@ -110,6 +110,10 @@ struct clocksource { 
	int			rating;

	enum clocksource_ids	id;

	enum vdso_clock_mode	vdso_clock_mode;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	u16			vdso_fix;

	u16			vdso_shift;

#endif

	unsigned long		flags;



	int			(*enable)(struct clocksource *cs);

include/vdso/datapage.h

+7 −1
Original line number Diff line number Diff line
@@ -69,7 +69,8 @@ struct vdso_timestamp { 
 * @tz_minuteswest:	minutes west of Greenwich

 * @tz_dsttime:		type of DST correction

 * @hrtimer_res:	hrtimer resolution

 * @__unused:		unused

 * @vdso_fix:		avoid the clock bug in VDSO

 * @vdso_shift: 	count of bit to be ignored

 * @arch_data:		architecture specific data (optional, defaults

 *			to an empty struct)

 *
@@ -104,7 +105,12 @@ struct vdso_data { 
	s32			tz_minuteswest;

	s32			tz_dsttime;

	u32			hrtimer_res;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	u16			vdso_fix;

	u16			vdso_shift;

#else

	u32			__unused;

#endif



	struct arch_vdso_data	arch_data;

};

kernel/time/vsyscall.c

+16 −0
Original line number Diff line number Diff line
@@ -74,14 +74,30 @@ void update_vsyscall(struct timekeeper *tk) 
	struct vdso_data *vdata = __arch_get_k_vdso_data();

	struct vdso_timestamp *vdso_ts;

	s32 clock_mode;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	u16 vdso_fix;

	u16 vdso_shift;

#endif

	u64 nsec;



	/* copy vsyscall data */

	vdso_write_begin(vdata);



	clock_mode = tk->tkr_mono.clock->vdso_clock_mode;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	vdso_fix = tk->tkr_mono.clock->vdso_fix;

	vdso_shift = tk->tkr_mono.clock->vdso_shift;

#endif

	vdata[CS_HRES_COARSE].clock_mode	= clock_mode;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	vdata[CS_HRES_COARSE].vdso_fix 		= vdso_fix;

	vdata[CS_HRES_COARSE].vdso_shift 	= vdso_shift;

#endif

	vdata[CS_RAW].clock_mode		= clock_mode;

#ifdef CONFIG_ARM_ARCH_TIMER_WORKAROUND_IN_USERSPACE

	vdata[CS_RAW].vdso_fix 			= vdso_fix;

	vdata[CS_RAW].vdso_shift 		= vdso_shift;

#endif



	/* CLOCK_REALTIME also required for time() */

	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];