Commit 0fa83fd0 authored by Xiongfeng Wang's avatar Xiongfeng Wang Committed by Zheng Zengkai
Browse files

sdei_watchdog: avoid possible false hardlockup 



hulk inclusion
category: feature
bugzilla: 48046
CVE: NA

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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>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent bdda54cc

arch/arm64/kernel/watchdog_sdei.c

+19 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
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);



int watchdog_nmi_enable(unsigned int cpu)

{
@@ -35,6 +36,7 @@ int watchdog_nmi_enable(unsigned int cpu) 
	refresh_hld_last_timestamp();

#endif



	__this_cpu_write(last_check_time, ktime_get_mono_fast_ns());

	sdei_api_set_secure_timer_period(watchdog_thresh);



	ret = sdei_api_event_enable(sdei_watchdog_event_num);
@@ -63,6 +65,23 @@ void watchdog_nmi_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);

		WARN_ON(1);

		return 0;

	}



	watchdog_hardlockup_check(regs);



	return 0;