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 <bsinghar...@gmail.com>
---
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
