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Subject[PATCH v8 6/7] powerpc/mce: Handle UE event for memcpy_mcsafe
Date
If we take a UE on one of the instructions with a fixup entry, set nip
to continue execution at the fixup entry. Stop processing the event
further or print it.

Co-developed-by: Reza Arbab <arbab@linux.ibm.com>
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
---
arch/powerpc/include/asm/mce.h | 4 +++-
arch/powerpc/kernel/mce.c | 18 ++++++++++++++++--
arch/powerpc/kernel/mce_power.c | 15 +++++++++++++--
3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/mce.h b/arch/powerpc/include/asm/mce.h
index f3a6036b6bc0..e1931c8c2743 100644
--- a/arch/powerpc/include/asm/mce.h
+++ b/arch/powerpc/include/asm/mce.h
@@ -122,7 +122,8 @@ struct machine_check_event {
enum MCE_UeErrorType ue_error_type:8;
u8 effective_address_provided;
u8 physical_address_provided;
- u8 reserved_1[5];
+ u8 ignore_event;
+ u8 reserved_1[4];
u64 effective_address;
u64 physical_address;
u8 reserved_2[8];
@@ -193,6 +194,7 @@ struct mce_error_info {
enum MCE_Initiator initiator:8;
enum MCE_ErrorClass error_class:8;
bool sync_error;
+ bool ignore_event;
};

#define MAX_MC_EVT 100
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index 8c0b471658a7..a80f5d6ef166 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -33,7 +33,6 @@ 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);
-static 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 = {
@@ -144,6 +143,7 @@ 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;
+ mce->u.ue_error.ignore_event = mce_err->ignore_event;
}
}
return;
@@ -256,8 +256,17 @@ static void machine_process_ue_event(struct work_struct *work)
/*
* This should probably queued elsewhere, but
* oh! well
+ *
+ * Don't report this machine check because the caller has a
+ * asked us to ignore the event, it has a fixup handler which
+ * will do the appropriate error handling and reporting.
*/
if (evt->error_type == MCE_ERROR_TYPE_UE) {
+ if (evt->u.ue_error.ignore_event) {
+ __this_cpu_dec(mce_ue_count);
+ continue;
+ }
+
if (evt->u.ue_error.physical_address_provided) {
unsigned long pfn;

@@ -291,8 +300,13 @@ static void machine_check_process_queued_event(struct irq_work *work)
index = __this_cpu_read(mce_queue_count) - 1;
evt = this_cpu_ptr(&mce_event_queue[index]);

- if (evt->error_type == MCE_ERROR_TYPE_UE)
+ if (evt->error_type == MCE_ERROR_TYPE_UE) {
machine_check_ue_event(evt);
+ if (evt->u.ue_error.ignore_event) {
+ __this_cpu_dec(mce_queue_count);
+ continue;
+ }
+ }

machine_check_print_event_info(evt, false, false);
__this_cpu_dec(mce_queue_count);
diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c
index bed38a8e2e50..36ca45bbb273 100644
--- a/arch/powerpc/kernel/mce_power.c
+++ b/arch/powerpc/kernel/mce_power.c
@@ -11,6 +11,7 @@

#include <linux/types.h>
#include <linux/ptrace.h>
+#include <linux/extable.h>
#include <asm/mmu.h>
#include <asm/mce.h>
#include <asm/machdep.h>
@@ -18,6 +19,7 @@
#include <asm/pte-walk.h>
#include <asm/sstep.h>
#include <asm/exception-64s.h>
+#include <asm/extable.h>

/*
* Convert an address related to an mm to a physical address.
@@ -558,9 +560,18 @@ static int mce_handle_derror(struct pt_regs *regs,
return 0;
}

-static long mce_handle_ue_error(struct pt_regs *regs)
+static long mce_handle_ue_error(struct pt_regs *regs,
+ struct mce_error_info *mce_err)
{
long handled = 0;
+ const struct exception_table_entry *entry;
+
+ entry = search_kernel_exception_table(regs->nip);
+ if (entry) {
+ mce_err->ignore_event = true;
+ regs->nip = extable_fixup(entry);
+ return 1;
+ }

/*
* On specific SCOM read via MMIO we may get a machine check
@@ -593,7 +604,7 @@ static long mce_handle_error(struct pt_regs *regs,
&phys_addr);

if (!handled && mce_err.error_type == MCE_ERROR_TYPE_UE)
- handled = mce_handle_ue_error(regs);
+ handled = mce_handle_ue_error(regs, &mce_err);

save_mce_event(regs, handled, &mce_err, regs->nip, addr, phys_addr);

--
2.20.1
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