From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x244.google.com (mail-pg0-x244.google.com [IPv6:2607:f8b0:400e:c05::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xsWWT2rjyzDqlw for ; Wed, 13 Sep 2017 16:11:17 +1000 (AEST) Received: by mail-pg0-x244.google.com with SMTP id d8so7219238pgt.3 for ; Tue, 12 Sep 2017 23:11:17 -0700 (PDT) From: Balbir Singh To: mpe@ellerman.id.au, npiggin@gmail.com, mahesh@linux.vnet.ibm.com Cc: linuxppc-dev@lists.ozlabs.org, Balbir Singh Subject: [PATCH v2 5/5] powerpc/mce: hookup memory_failure for UE errors Date: Wed, 13 Sep 2017 16:10:49 +1000 Message-Id: <20170913061049.13256-6-bsingharora@gmail.com> In-Reply-To: <20170913061049.13256-1-bsingharora@gmail.com> References: <20170913061049.13256-1-bsingharora@gmail.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , If we are in user space and hit a UE error, we now have the basic infrastructure to walk the page tables and find out the effective address that was accessed, since the DAR is not valid. We use a work_queue content to hookup the bad pfn, any other context causes problems, since memory_failure itself can call into schedule() via lru_drain_ bits. We could probably poison the struct page to avoid a race between detection and taking corrective action. Signed-off-by: Balbir Singh --- arch/powerpc/kernel/mce.c | 67 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 64 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c index c7acc33..f20345a 100644 --- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c @@ -39,11 +39,21 @@ static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], mce_event); static DEFINE_PER_CPU(int, mce_queue_count); static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], mce_event_queue); +/* Queue for delayed MCE UE events. */ +static DEFINE_PER_CPU(int, mce_ue_count); +static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], + mce_ue_event_queue); + static void machine_check_process_queued_event(struct irq_work *work); +void machine_check_ue_event(struct machine_check_event *evt); +static void machine_process_ue_event(struct work_struct *work); + static struct irq_work mce_event_process_work = { .func = machine_check_process_queued_event, }; +DECLARE_WORK(mce_ue_event_work, machine_process_ue_event); + static void mce_set_error_info(struct machine_check_event *mce, struct mce_error_info *mce_err) { @@ -143,6 +153,7 @@ void save_mce_event(struct pt_regs *regs, long handled, if (phys_addr != ULONG_MAX) { mce->u.ue_error.physical_address_provided = true; mce->u.ue_error.physical_address = phys_addr; + machine_check_ue_event(mce); } } return; @@ -197,6 +208,26 @@ void release_mce_event(void) get_mce_event(NULL, true); } + +/* + * Queue up the MCE event which then can be handled later. + */ +void machine_check_ue_event(struct machine_check_event *evt) +{ + int index; + + index = __this_cpu_inc_return(mce_ue_count) - 1; + /* If queue is full, just return for now. */ + if (index >= MAX_MC_EVT) { + __this_cpu_dec(mce_ue_count); + return; + } + memcpy(this_cpu_ptr(&mce_ue_event_queue[index]), evt, sizeof(*evt)); + + /* Queue work to process this event later. */ + schedule_work(&mce_ue_event_work); +} + /* * Queue up the MCE event which then can be handled later. */ @@ -219,7 +250,36 @@ void machine_check_queue_event(void) /* Queue irq work to process this event later. */ irq_work_queue(&mce_event_process_work); } - +/* + * process pending MCE event from the mce event queue. This function will be + * called during syscall exit. + */ +static void machine_process_ue_event(struct work_struct *work) +{ + int index; + struct machine_check_event *evt; + + while (__this_cpu_read(mce_ue_count) > 0) { + index = __this_cpu_read(mce_ue_count) - 1; + evt = this_cpu_ptr(&mce_ue_event_queue[index]); +#ifdef CONFIG_MEMORY_FAILURE + /* + * This should probably queued elsewhere, but + * oh! well + */ + if (evt->error_type == MCE_ERROR_TYPE_UE) { + if (evt->u.ue_error.physical_address_provided) + memory_failure(evt->u.ue_error.physical_address, + SIGBUS, 0); + else + pr_warn("Failed to identify bad address from " + "where the uncorrectable error (UE) " + "was generated\n"); + } +#endif + __this_cpu_dec(mce_ue_count); + } +} /* * process pending MCE event from the mce event queue. This function will be * called during syscall exit. @@ -227,6 +287,7 @@ void machine_check_queue_event(void) static void machine_check_process_queued_event(struct irq_work *work) { int index; + struct machine_check_event *evt; add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); @@ -236,8 +297,8 @@ static void machine_check_process_queued_event(struct irq_work *work) */ while (__this_cpu_read(mce_queue_count) > 0) { index = __this_cpu_read(mce_queue_count) - 1; - machine_check_print_event_info( - this_cpu_ptr(&mce_event_queue[index]), false); + evt = this_cpu_ptr(&mce_event_queue[index]); + machine_check_print_event_info(evt, false); __this_cpu_dec(mce_queue_count); } } -- 2.9.5