powerpc/pseries: Display machine check error details.

Extract the MCE error details from RTAS extended log and display it to
console.

With this patch you should now see mce logs like below:

[  142.371818] Severe Machine check interrupt [Recovered]
[  142.371822]   NIP [d00000000ca301b8]: init_module+0x1b8/0x338 [bork_kernel]
[  142.371822]   Initiator: CPU
[  142.371823]   Error type: SLB [Multihit]
[  142.371824]     Effective address: d00000000ca70000

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/rtas.h

@@ -197,6 +197,11 @@ static inline uint8_t rtas_error_extended(const struct rtas_error_log *elog)
 	return (elog->byte1 & 0x04) >> 2;
 }
 
+static inline uint8_t rtas_error_initiator(const struct rtas_error_log *elog)
+{
+	return (elog->byte2 & 0xf0) >> 4;
+}
+
 #define rtas_error_type(x)	((x)->byte3)
 
 static inline

arch/powerpc/platforms/pseries/ras.c

@@ -523,6 +523,136 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
 	return 0; /* need to perform reset */
 }
 
+#define VAL_TO_STRING(ar, val)	\
+	(((val) < ARRAY_SIZE(ar)) ? ar[(val)] : "Unknown")
+
+static void pseries_print_mce_info(struct pt_regs *regs,
+				   struct rtas_error_log *errp)
+{
+	const char *level, *sevstr;
+	struct pseries_errorlog *pseries_log;
+	struct pseries_mc_errorlog *mce_log;
+	u8 error_type, err_sub_type;
+	u64 addr;
+	u8 initiator = rtas_error_initiator(errp);
+	int disposition = rtas_error_disposition(errp);
+
+	static const char * const initiators[] = {
+		"Unknown",
+		"CPU",
+		"PCI",
+		"ISA",
+		"Memory",
+		"Power Mgmt",
+	};
+	static const char * const mc_err_types[] = {
+		"UE",
+		"SLB",
+		"ERAT",
+		"TLB",
+		"D-Cache",
+		"Unknown",
+		"I-Cache",
+	};
+	static const char * const mc_ue_types[] = {
+		"Indeterminate",
+		"Instruction fetch",
+		"Page table walk ifetch",
+		"Load/Store",
+		"Page table walk Load/Store",
+	};
+
+	/* SLB sub errors valid values are 0x0, 0x1, 0x2 */
+	static const char * const mc_slb_types[] = {
+		"Parity",
+		"Multihit",
+		"Indeterminate",
+	};
+
+	/* TLB and ERAT sub errors valid values are 0x1, 0x2, 0x3 */
+	static const char * const mc_soft_types[] = {
+		"Unknown",
+		"Parity",
+		"Multihit",
+		"Indeterminate",
+	};
+
+	if (!rtas_error_extended(errp)) {
+		pr_err("Machine check interrupt: Missing extended error log\n");
+		return;
+	}
+
+	pseries_log = get_pseries_errorlog(errp, PSERIES_ELOG_SECT_ID_MCE);
+	if (pseries_log == NULL)
+		return;
+
+	mce_log = (struct pseries_mc_errorlog *)pseries_log->data;
+
+	error_type = mce_log->error_type;
+	err_sub_type = rtas_mc_error_sub_type(mce_log);
+
+	switch (rtas_error_severity(errp)) {
+	case RTAS_SEVERITY_NO_ERROR:
+		level = KERN_INFO;
+		sevstr = "Harmless";
+		break;
+	case RTAS_SEVERITY_WARNING:
+		level = KERN_WARNING;
+		sevstr = "";
+		break;
+	case RTAS_SEVERITY_ERROR:
+	case RTAS_SEVERITY_ERROR_SYNC:
+		level = KERN_ERR;
+		sevstr = "Severe";
+		break;
+	case RTAS_SEVERITY_FATAL:
+	default:
+		level = KERN_ERR;
+		sevstr = "Fatal";
+		break;
+	}
+
+	printk("%s%s Machine check interrupt [%s]\n", level, sevstr,
+	       disposition == RTAS_DISP_FULLY_RECOVERED ?
+	       "Recovered" : "Not recovered");
+	if (user_mode(regs)) {
+		printk("%s  NIP: [%016lx] PID: %d Comm: %s\n", level,
+		       regs->nip, current->pid, current->comm);
+	} else {
+		printk("%s  NIP [%016lx]: %pS\n", level, regs->nip,
+		       (void *)regs->nip);
+	}
+	printk("%s  Initiator: %s\n", level,
+	       VAL_TO_STRING(initiators, initiator));
+
+	switch (error_type) {
+	case MC_ERROR_TYPE_UE:
+		printk("%s  Error type: %s [%s]\n", level,
+		       VAL_TO_STRING(mc_err_types, error_type),
+		       VAL_TO_STRING(mc_ue_types, err_sub_type));
+		break;
+	case MC_ERROR_TYPE_SLB:
+		printk("%s  Error type: %s [%s]\n", level,
+		       VAL_TO_STRING(mc_err_types, error_type),
+		       VAL_TO_STRING(mc_slb_types, err_sub_type));
+		break;
+	case MC_ERROR_TYPE_ERAT:
+	case MC_ERROR_TYPE_TLB:
+		printk("%s  Error type: %s [%s]\n", level,
+		       VAL_TO_STRING(mc_err_types, error_type),
+		       VAL_TO_STRING(mc_soft_types, err_sub_type));
+		break;
+	default:
+		printk("%s  Error type: %s\n", level,
+		       VAL_TO_STRING(mc_err_types, error_type));
+		break;
+	}
+
+	addr = rtas_mc_get_effective_addr(mce_log);
+	if (addr)
+		printk("%s    Effective address: %016llx\n", level, addr);
+}
+
 static int mce_handle_error(struct rtas_error_log *errp)
 {
 	struct pseries_errorlog *pseries_log;
@@ -585,8 +715,11 @@ static int recover_mce(struct pt_regs *regs, struct rtas_error_log *err)
 	int recovered = 0;
 	int disposition = rtas_error_disposition(err);
 
+	pseries_print_mce_info(regs, err);
+
 	if (!(regs->msr & MSR_RI)) {
 		/* If MSR_RI isn't set, we cannot recover */
+		pr_err("Machine check interrupt unrecoverable: MSR(RI=0)\n");
 		recovered = 0;
 
 	} else if (disposition == RTAS_DISP_FULLY_RECOVERED) {