From 6ed88a56c790431e74e664fb45f9fe91bd4dd338 Mon Sep 17 00:00:00 2001 From: leoliu-oc Date: Fri, 16 Aug 2024 11:07:10 +0800 Subject: [PATCH] x86/hpet: Read HPET directly if panic in progress MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit zhaoxin inclusion category: other ------------------- When the clocksource of the system is HPET，a CPU executing read_hpet might be interrupted by #GP/#PF to executing the panic，this may lead to read_hpet dead loops: CPU x CPU x ---- ---- read_hpet() arch_spin_trylock(&hpet.lock) [CPU x got the hpet.lock] #GP/#PF happened panic() kmsg_dump() pstore_dump() pstore_record_init() ktime_get_real_fast_ns() read_hpet() [dead loops] To avoid this dead loops, read HPET directly if panic in progress. Signed-off-by: leoliu-oc --- arch/x86/kernel/hpet.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 046bc9d57e99..2626fa052b45 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -804,6 +804,12 @@ static u64 read_hpet(struct clocksource *cs) if (in_nmi()) return (u64)hpet_readl(HPET_COUNTER); + /* + * Read HPET directly if panic in progress. + */ + if (unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID)) + return (u64)hpet_readl(HPET_COUNTER); + /* * Read the current state of the lock and HPET value atomically. */ -- Gitee