Commit cac525db authored by Xiongfeng Wang's avatar Xiongfeng Wang
Browse files

sdei_watchdog: avoid possible false hardlockup 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LQCC


CVE: NA

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

Firmware may not trigger SDEI event as required frequency. SDEI event
may be triggered too soon, which cause false hardlockup in kernel. Check
the time stamp in sdei_watchdog_callbak and skip the hardlockup check if
it is invoked too soon.

Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: default avatarHanjun Guo <guohanjun@huawei.com>

 Conflicts:
	arch/arm64/kernel/watchdog_sdei.c (context conflict)
Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
parent 7fc50336

arch/arm64/kernel/watchdog_sdei.c

+18 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
static int sdei_watchdog_event_num;

static bool disable_sdei_nmi_watchdog;

static bool sdei_watchdog_registered;

static DEFINE_PER_CPU(ktime_t, last_check_time);



void watchdog_hardlockup_enable(unsigned int cpu)

{
@@ -34,6 +35,7 @@ void watchdog_hardlockup_enable(unsigned int cpu) 
	 * secure timer correctly */

	watchdog_hardlockup_touch_cpu(cpu);

	sdei_api_set_secure_timer_period(watchdog_thresh);

	__this_cpu_write(last_check_time, ktime_get_mono_fast_ns());



	ret = sdei_api_event_enable(sdei_watchdog_event_num);

	if (ret) {
@@ -58,6 +60,22 @@ void watchdog_hardlockup_disable(unsigned int cpu) 
static int sdei_watchdog_callback(u32 event,

		struct pt_regs *regs, void *arg)

{

	ktime_t delta, now = ktime_get_mono_fast_ns();



	delta = now - __this_cpu_read(last_check_time);

	__this_cpu_write(last_check_time, now);



	/*

	 * Set delta to 4/5 of the actual watchdog threshold period so the

	 * hrtimer is guaranteed to fire at least once within the real

	 * watchdog threshold.

	 */

	if (delta < watchdog_thresh * (u64)NSEC_PER_SEC * 4 / 5) {

		pr_err(FW_BUG "SDEI Watchdog event triggered too soon, "

			"time to last check:%lld ns\n", delta);

		return 0;

	}



	watchdog_hardlockup_check(smp_processor_id(), regs);



	return 0;