arm64: arch_timer: Disable CNTVCT_EL0 trap if workaround is enabled

hulk inclusion
category: feature
bugzilla: 47984
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: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/clocksource/arm_arch_timer.c

@@ -74,6 +74,8 @@ 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 */
+static bool vdso_fix;
+static u16 vdso_shift;
 
 static cpumask_t evtstrm_available = CPU_MASK_NONE;
 static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
@@ -572,8 +574,17 @@ 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) {
-		clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;
-		vdso_default = VDSO_CLOCKMODE_NONE;
+		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;
+		} else {
+			clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;
+			vdso_default = VDSO_CLOCKMODE_NONE;
+		}
 	} else if (wa->disable_compat_vdso && vdso_default != VDSO_CLOCKMODE_NONE) {
 		vdso_default = VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT;
 		clocksource_counter.vdso_clock_mode = vdso_default;
@@ -859,7 +870,7 @@ 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())
+	if (arch_timer_this_cpu_has_cntvct_wa() && !vdso_fix)
 		pr_info("CPU%d: Trapping CNTVCT access\n", smp_processor_id());
 	else
 		cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
@@ -1015,6 +1026,8 @@ static void __init arch_counter_register(unsigned type)
 
 		arch_timer_read_counter = rd;
 		clocksource_counter.vdso_clock_mode = vdso_default;
+		clocksource_counter.vdso_fix = vdso_fix;
+		clocksource_counter.vdso_shift = vdso_shift;
 	} else {
 		arch_timer_read_counter = arch_counter_get_cntvct_mem;
 	}

include/linux/clocksource.h

@@ -101,6 +101,8 @@ struct clocksource {
 	struct list_head	list;
 	int			rating;
 	enum vdso_clock_mode	vdso_clock_mode;
+	u16			vdso_fix;
+	u16			vdso_shift;
 	unsigned long		flags;
 
 	int			(*enable)(struct clocksource *cs);

include/vdso/datapage.h

@@ -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 +105,8 @@ struct vdso_data {
 	s32			tz_minuteswest;
 	s32			tz_dsttime;
 	u32			hrtimer_res;
-	u32			__unused;
+	u16			vdso_fix;
+	u16			vdso_shift;
 
 	struct arch_vdso_data	arch_data;
 };

kernel/time/vsyscall.c

@@ -74,14 +74,22 @@ void update_vsyscall(struct timekeeper *tk)
 	struct vdso_data *vdata = __arch_get_k_vdso_data();
 	struct vdso_timestamp *vdso_ts;
 	s32 clock_mode;
+	u16 vdso_fix;
+	u16 vdso_shift;
 	u64 nsec;
 
 	/* copy vsyscall data */
 	vdso_write_begin(vdata);
 
 	clock_mode = tk->tkr_mono.clock->vdso_clock_mode;
+	vdso_fix = tk->tkr_mono.clock->vdso_fix;
+	vdso_shift = tk->tkr_mono.clock->vdso_shift;
 	vdata[CS_HRES_COARSE].clock_mode	= clock_mode;
+	vdata[CS_HRES_COARSE].vdso_fix 		= vdso_fix;
+	vdata[CS_HRES_COARSE].vdso_shift 	= vdso_shift;
 	vdata[CS_RAW].clock_mode		= clock_mode;
+	vdata[CS_RAW].vdso_fix 			= vdso_fix;
+	vdata[CS_RAW].vdso_shift 		= vdso_shift;
 
 	/* CLOCK_REALTIME also required for time() */
 	vdso_ts		= &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];