Re: [v3 PATCH 5/5] powerpc/pseries: Display machine check error details.

On 06/08/2018 07:21 AM, Nicholas Piggin wrote:

On Thu, 07 Jun 2018 22:59:04 +0530
Mahesh J Salgaonkar [off-list ref] wrote:

quoted

From: Mahesh Salgaonkar <redacted>

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 <redacted>
---
 arch/powerpc/include/asm/rtas.h      |    5 +
 arch/powerpc/platforms/pseries/ras.c |  128 +++++++++++++++++++++++++++++++++-
 2 files changed, 131 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 3f2fba7ef23b..8100a95c133a 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h

@@ -190,6 +190,11 @@ 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

diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index e56759d92356..cd9446980092 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c

@@ -422,7 +422,130 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
 	return 0; /* need to perform reset */
 }
 
-static int mce_handle_error(struct rtas_error_log *errp)
+#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, int disposition)
+{
+	const char *level, *sevstr;
+	struct pseries_errorlog *pseries_log;
+	struct pseries_mc_errorlog *mce_log;
+	uint8_t error_type, err_sub_type;
+	uint8_t initiator = rtas_error_initiator(errp);
+	uint64_t addr;
+
+	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",
+	};
+
+	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 = rtas_mc_error_type(mce_log);
+	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);
+	}

I think it's probably still useful to print pid/comm for kernel mode
faults if !in_interrupt()... I see you're basically taking kernel/mce.c
and doing the same thing.

Is there any reasonable way to share code here?

I did think of doing that, but I wanted make this patch series simple
enough to be able to make backport easy for very old kernels. I will
work on consolidating the code as enhancement later.

Thanks,
-Mahesh.