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powerpc/mce: hookup memory_failure for UE errors 

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 <bsingharora@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Balbir Singh 2017-09-29 14:26:55 +10:00 committed by Michael Ellerman
parent 01eaac2b05
commit 733e4a4c44
1 changed files with 66 additions and 2 deletions
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68
arch/powerpc/kernel/mce.c
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@ -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 +250,39 @@ 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) {
unsigned long pfn;
pfn = evt->u.ue_error.physical_address >>
PAGE_SHIFT;
memory_failure(pfn, 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 +290,7 @@ 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 +300,8 @@ 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);
}
}