[PATCH 2/2] powerpc/book3s: Display task info for MCE error in user mode.

[Mahesh J Salgaonkar]

From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

For MCE that hit while in use mode MSR(HV=1,PR=1), print the task info on the
console MCE error log. This will help to identify application that stumbled
upon MCE error.

After this patch the MCE console log would look like:

[    1.268998] Severe Machine check interrupt [Recovered]
[    1.269024]   NIP: [0000000010039778] PID: 762 Comm: ebizzy
[    1.269048]   Initiator: CPU
[    1.269067]   Error type: SLB [Multihit]
[    1.269088]     Effective address: 0000000010039778

[    1.855084] Severe Machine check interrupt [Not recovered]
[    1.855111]   NIP: [0000000010039778] PID: 763 Comm: ebizzy
[    1.855135]   Initiator: CPU
[    1.855154]   Error type: UE [Page table walk ifetch]
[    1.855179]     Effective address: 0000000010039778
[    1.855210] ebizzy[763]: unhandled signal 7 at 0000000010039778 nip 0000000010039778 lr 0000000010001b44 code 30004

Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/mce.h        |    3 ++-
 arch/powerpc/kernel/mce.c             |   12 +++++++++---
 arch/powerpc/platforms/powernv/opal.c |    2 +-
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/mce.h b/arch/powerpc/include/asm/mce.h
index e3498b4..0d865fe 100644
--- a/arch/powerpc/include/asm/mce.h
+++ b/arch/powerpc/include/asm/mce.h
@@ -207,7 +207,8 @@ extern void save_mce_event(struct pt_regs *regs, long handled,
 extern int get_mce_event(struct machine_check_event *mce, bool release);
 extern void release_mce_event(void);
 extern void machine_check_queue_event(void);
-extern void machine_check_print_event_info(struct machine_check_event *evt);
+extern void machine_check_print_event_info(struct machine_check_event *evt,
+							bool user_mode);
 extern uint64_t get_mce_fault_addr(struct machine_check_event *evt);
 
 #endif /* __ASM_PPC64_MCE_H__ */
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index e82d4ee..304cbaf 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -228,12 +228,13 @@ 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]));
+				this_cpu_ptr(&mce_event_queue[index]), false);
 		__this_cpu_dec(mce_queue_count);
 	}
 }
 
-void machine_check_print_event_info(struct machine_check_event *evt)
+void machine_check_print_event_info(struct machine_check_event *evt,
+								bool user_mode)
 {
 	const char *level, *sevstr, *subtype;
 	static const char *mc_ue_types[] = {
@@ -311,8 +312,13 @@ void machine_check_print_event_info(struct machine_check_event *evt)
 	printk("%s%s Machine check interrupt [%s]\n", level, sevstr,
 	       evt->disposition == MCE_DISPOSITION_RECOVERED ?
 	       "Recovered" : "Not recovered");
-	printk("%s  NIP [%016llx]: %pS\n", level, evt->srr0,
+	if (user_mode) {
+		printk("%s  NIP: [%016llx] PID: %d Comm: %s\n", level,
+				evt->srr0, current->pid, current->comm);
+	} else {
+		printk("%s  NIP [%016llx]: %pS\n", level, evt->srr0,
 							(void *)evt->srr0);
+	}
 	printk("%s  Initiator: %s\n", level,
 	       evt->initiator == MCE_INITIATOR_CPU ? "CPU" : "Unknown");
 	switch (evt->error_type) {
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index e0f856b..296c942 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -435,7 +435,7 @@ int opal_machine_check(struct pt_regs *regs)
 		       evt.version);
 		return 0;
 	}
-	machine_check_print_event_info(&evt);
+	machine_check_print_event_info(&evt, user_mode(regs));
 
 	if (opal_recover_mce(regs, &evt))
 		return 1;