Re: [PATCH v3 1/8] trace: ras: add ARM processor error information trace event

[Xie XiuQi <xiexiuqi@huawei.com>]

Hi Steve,

Sorry for reply late.

On 2017/3/31 0:02, Steven Rostedt wrote:
> On Thu, 30 Mar 2017 18:31:01 +0800
> Xie XiuQi <xiexiuqi@huawei.com> wrote:
> 
>> Add a new trace event for ARM processor error information, so that
>> the user will know what error occurred. With this information the
>> user may take appropriate action.
>>
>> These trace events are consistent with the ARM processor error
>> information table which defined in UEFI 2.6 spec section N.2.4.4.1.
>>
>> ---
>> v2: add trace enabled condition as Steven's suggestion.
>>     fix a typo.
>> ---
>>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: Tyler Baicar <tbaicar@codeaurora.org>
>> Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
>> ---
>>  drivers/acpi/apei/ghes.c | 10 ++++++
>>  include/linux/cper.h     |  5 +++
>>  include/ras/ras_event.h  | 87 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 102 insertions(+)
>>
>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
>> index 81eabc6..6be0333 100644
>> --- a/drivers/acpi/apei/ghes.c
>> +++ b/drivers/acpi/apei/ghes.c
>> @@ -518,9 +518,19 @@ static void ghes_do_proc(struct ghes *ghes,
>>  		else if (!uuid_le_cmp(sec_type, CPER_SEC_PROC_ARM) &&
>>  			 trace_arm_event_enabled()) {
>>  			struct cper_sec_proc_arm *arm_err;
>> +			struct cper_arm_err_info *err_info;
>> +			int i;
>>  
>>  			arm_err = acpi_hest_generic_data_payload(gdata);
>>  			trace_arm_event(arm_err);
>> +
>> +			if (trace_arm_proc_err_enabled()) {
>> +				err_info = (struct cper_arm_err_info *)(arm_err + 1);
>> +				for (i = 0; i < arm_err->err_info_num; i++) {
>> +					trace_arm_proc_err(err_info);
>> +					err_info += 1;
>> +				}
>> +			}
>>  		} else if (trace_unknown_sec_event_enabled()) {
>>  			void *unknown_err = acpi_hest_generic_data_payload(gdata);
>>  			trace_unknown_sec_event(&sec_type,
>> diff --git a/include/linux/cper.h b/include/linux/cper.h
>> index 85450f3..0cae900 100644
>> --- a/include/linux/cper.h
>> +++ b/include/linux/cper.h
>> @@ -270,6 +270,11 @@ enum {
>>  #define CPER_ARM_INFO_VALID_VIRT_ADDR		0x0008
>>  #define CPER_ARM_INFO_VALID_PHYSICAL_ADDR	0x0010
>>  
>> +#define CPER_ARM_INFO_TYPE_CACHE		0
>> +#define CPER_ARM_INFO_TYPE_TLB			1
>> +#define CPER_ARM_INFO_TYPE_BUS			2
>> +#define CPER_ARM_INFO_TYPE_UARCH		3
>> +
>>  #define CPER_ARM_INFO_FLAGS_FIRST		0x0001
>>  #define CPER_ARM_INFO_FLAGS_LAST		0x0002
>>  #define CPER_ARM_INFO_FLAGS_PROPAGATED		0x0004
>> diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
>> index 13befad..026b094 100644
>> --- a/include/ras/ras_event.h
>> +++ b/include/ras/ras_event.h
>> @@ -206,6 +206,93 @@
>>  		  __entry->running_state, __entry->psci_state)
>>  );
>>  
>> +#define ARM_PROC_ERR_TYPE	\
>> +	EM ( CPER_ARM_INFO_TYPE_CACHE, "cache error" )	\
>> +	EM ( CPER_ARM_INFO_TYPE_TLB,  "TLB error" )	\
>> +	EM ( CPER_ARM_INFO_TYPE_BUS, "bus error" )	\
>> +	EMe ( CPER_ARM_INFO_TYPE_UARCH, "micro-architectural error" )
>> +
>> +#define ARM_PROC_ERR_FLAGS	\
>> +	EM ( CPER_ARM_INFO_FLAGS_FIRST, "First error captured" )	\
>> +	EM ( CPER_ARM_INFO_FLAGS_LAST,  "Last error captured" )	\
>> +	EM ( CPER_ARM_INFO_FLAGS_PROPAGATED, "Propagated" )	\
>> +	EMe ( CPER_ARM_INFO_FLAGS_OVERFLOW, "Overflow" )
>> +
> 
> Can flags have more than one bit set?

Yes, indeed. ARM_PROC_ERR_FLAGS might have more than on bit set.
Could we use __print_flags instead? like:

#define show_proc_err_flags(flags) __print_flags(flags, "|",			\
	{ CPER_ARM_INFO_FLAGS_FIRST,		"First error captured" },	\
	{ CPER_ARM_INFO_FLAGS_LAST,		"Last error captured" },	\
	{ CPER_ARM_INFO_FLAGS_PROPAGATED,	"Propagated" },			\
	{ CPER_ARM_INFO_FLAGS_OVERFLOW,		"Overflow" }}

> 
>> +/*
>> + * First define the enums in MM_ACTION_RESULT to be exported to userspace
>> + * via TRACE_DEFINE_ENUM().
>> + */
>> +#undef EM
>> +#undef EMe
>> +#define EM(a, b) TRACE_DEFINE_ENUM(a);
>> +#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
>> +
>> +ARM_PROC_ERR_TYPE
>> +ARM_PROC_ERR_FLAGS
>> +
>> +/*
>> + * Now redefine the EM() and EMe() macros to map the enums to the strings
>> + * that will be printed in the output.
>> + */
>> +#undef EM
>> +#undef EMe
>> +#define EM(a, b)		{ a, b },
>> +#define EMe(a, b)	{ a, b }
>> +
>> +TRACE_EVENT(arm_proc_err,
>> +
>> +	TP_PROTO(const struct cper_arm_err_info *err),
>> +
>> +	TP_ARGS(err),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(u8, type)
>> +		__field(u16, multiple_error)
>> +		__field(u8, flags)
>> +		__field(u64, error_info)
>> +		__field(u64, virt_fault_addr)
>> +		__field(u64, physical_fault_addr)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->type = err->type;
>> +
>> +		if (err->validation_bits & CPER_ARM_INFO_VALID_MULTI_ERR)
>> +			__entry->multiple_error = err->multiple_error;
>> +		else
>> +			__entry->multiple_error = ~0;
>> +
>> +		if (err->validation_bits & CPER_ARM_INFO_VALID_FLAGS)
>> +			__entry->flags = err->flags;
>> +		else
>> +			__entry->flags = ~0;
>> +
>> +		if (err->validation_bits & CPER_ARM_INFO_VALID_ERR_INFO)
>> +			__entry->error_info = err->error_info;
>> +		else
>> +			__entry->error_info = 0ULL;
>> +
>> +		if (err->validation_bits & CPER_ARM_INFO_VALID_VIRT_ADDR)
>> +			__entry->virt_fault_addr = err->virt_fault_addr;
>> +		else
>> +			__entry->virt_fault_addr = 0ULL;
>> +
>> +		if (err->validation_bits & CPER_ARM_INFO_VALID_PHYSICAL_ADDR)
>> +			__entry->physical_fault_addr = err->physical_fault_addr;
>> +		else
>> +			__entry->physical_fault_addr = 0ULL;
> 
> else statements add a lot of branch conditions, and kills the branch
> prediction. What about setting up default values, and then setting only
> if the if statement is true.
> 
> 
> 	memset(&__entry->error_info, 0,
> 	       sizeof(__entry) - offsetof(typeof(__entry), error_info)));
> 	__entry->multiple_error = ~0;
> 	__entry->flags = ~0;
> 
> 	if (...)

I'll use this style next version, thanks.

> 
>> +	),
>> +
>> +	TP_printk("ARM Processor Error: type %s; count: %u; flags: %s;"
>> +		  " error info: %016llx; virtual address: %016llx;"
>> +		  " physical address: %016llx",
>> +		  __print_symbolic(__entry->type, ARCH_PROC_ERR_TYPE),
>> +		  __entry->multiple_error,
>> +		  __print_symbolic(__entry->flags, ARCH_PROC_ERR_FLAGS),
> 
> Again, can flags have more than one bit set? If so, then this wont work.
> 
> -- Steve
> 
>> +		  __entry->error_info, __entry->virt_fault_addr,
>> +		  __entry->physical_fault_addr)
>> +);
>> +
>>  /*
>>   * Unknown Section Report
>>   *
> 
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> 
> .
> 

-- 
Thanks,
Xie XiuQi