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

[Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>]

On 06/08/2018 07:21 AM, Nicholas Piggin wrote:
> On Thu, 07 Jun 2018 22:59:04 +0530
> Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com> wrote:
> 
>> From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
>>
>> 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>
>> ---
>>  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.