[PATCH v.23-2] RAS: use tracepoint to handle hw issues

From: Mauro Carvalho Chehab
Date: Fri May 11 2012 - 10:54:31 EST

Add a new tracepoint-based hardware events report method for
reporting Memory Controller events.

Part of the description bellow is shamelessly copied from Tony
Luck's notes about the Hardware Error BoF during LPC 2010 [1].
Tony, thanks for your notes and discussions to generate the
h/w error reporting requirements.

[1] http://lwn.net/Articles/416669/

We have several subsystems & methods for reporting hardware errors:

1) EDAC ("Error Detection and Correction"). In its original form
this consisted of a platform specific driver that read topology
information and error counts from chipset registers and reported
the results via a sysfs interface.

2) mcelog - x86 specific decoding of machine check bank registers
reporting in binary form via /dev/mcelog. Recent additions make use
of the APEI extensions that were documented in version 4.0a of the
ACPI specification to acquire more information about errors without
having to rely reading chipset registers directly. A user level
programs decodes into somewhat human readable format.

3) drivers/edac/mce_amd.c - this driver hooks into the mcelog path and
decodes errors reported via machine check bank registers in AMD
processors to the console log using printk();

Each of these mechanisms has a band of followers ... and none
of them appear to meet all the needs of all users.

As part of a RAS subsystem, let's encapsulate the memory error hardware
events into a trace facility.

The tracepoint printk will be displayed like:

mc_event: (Corrected|Uncorrected|Fatal) error:[error msg] on memory stick "[label]" ([location] [edac_mc detail] [driver_detail])

[error msg] is the driver-specific error message
(e. g. "memory read", "bus error", ...);
[location] is the location in terms of memory controller and
branch/channel/slot, channel/slot or csrow/channel;
[label] is the memory stick label;
[edac_mc detail] describes the address location of the error
and the syndrome;
[driver detail] is driver-specifig error message details,
when needed/provided (e. g. "area:DMA", ...)

For example:

mc_event: Corrected error:memory read on memory stick "DIMM_1A" (mc:0 channel:0 slot:0 page:0x586b6e offset:0xa66 grain:32 syndrome:0x0 area:DMA)

Of course, any userspace tools meant to handle errors should not parse
the above data. They should, instead, use the binary fields provided by
the tracepoint, mapping them directly into their MIBs.

NOTE: The original patch was providing an additional mechanism for
MCA-based trace events that also contained MCA error register data.
Hoever, as no agreement was reached so far for the MCA-based trace
events, for now, let's add events only for memory errors.
A latter patch is planned to change the tracepoint, for those types
of event.

Reviewed-by: Aristeu Rozanski <arozansk@xxxxxxxxxx>
Cc: Doug Thompson <norsk5@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
drivers/edac/edac_core.h | 2 +-
drivers/edac/edac_mc.c | 25 ++++++++++----
include/ras/ras_event.h | 78 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 97 insertions(+), 8 deletions(-)
create mode 100644 include/ras/ras_event.h

diff --git a/drivers/edac/edac_core.h b/drivers/edac/edac_core.h
index f06ce9a..eee7360 100644
--- a/drivers/edac/edac_core.h
+++ b/drivers/edac/edac_core.h
@@ -468,7 +468,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
const int layer2,
const char *msg,
const char *other_detail,
- const void *mcelog);
+ const void *arch_log);

* edac_device APIs
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index e5b5563..0153cd98 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -33,6 +33,10 @@
#include "edac_core.h"
#include "edac_module.h"

+#define TRACE_INCLUDE_PATH ../../include/ras
+#include <ras/ras_event.h>
/* lock to memory controller's control array */
static DEFINE_MUTEX(mem_ctls_mutex);
static LIST_HEAD(mc_devices);
@@ -381,6 +385,7 @@ struct mem_ctl_info *edac_mc_alloc(unsigned mc_num,
* which will perform kobj unregistration and the actual free
* will occur during the kobject callback operation
return mci;
@@ -982,7 +987,7 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,
const int layer2,
const char *msg,
const char *other_detail,
- const void *mcelog)
+ const void *arch_log)
/* FIXME: too much for stack: move it to some pre-alocated area */
char detail[80], location[80];
@@ -1119,21 +1124,27 @@ void edac_mc_handle_error(const enum hw_event_mc_err_type type,

/* Memory type dependent details about the error */
- if (type == HW_EVENT_ERR_CORRECTED) {
snprintf(detail, sizeof(detail),
"page:0x%lx offset:0x%lx grain:%d syndrome:0x%lx",
page_frame_number, offset_in_page,
grain, syndrome);
- edac_ce_error(mci, pos, msg, location, label, detail,
- other_detail, enable_per_layer_report,
- page_frame_number, offset_in_page, grain);
- } else {
+ else
snprintf(detail, sizeof(detail),
"page:0x%lx offset:0x%lx grain:%d",
page_frame_number, offset_in_page, grain);

+ /* Report the error via the trace interface */
+ trace_mc_event(type, mci->mc_idx, msg, label, location,
+ detail, other_detail);
+ /* Report the error via the edac_mc_printk() interface */
+ edac_ce_error(mci, pos, msg, location, label, detail,
+ other_detail, enable_per_layer_report,
+ page_frame_number, offset_in_page, grain);
+ else
edac_ue_error(mci, pos, msg, location, label, detail,
other_detail, enable_per_layer_report);
- }
diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
new file mode 100644
index 0000000..66f6a43
--- /dev/null
+++ b/include/ras/ras_event.h
@@ -0,0 +1,78 @@
+#define TRACE_SYSTEM ras
+#define TRACE_INCLUDE_FILE ras_event
+#if !defined(_TRACE_HW_EVENT_MC_H) || defined(TRACE_HEADER_MULTI_READ)
+#include <linux/tracepoint.h>
+#include <linux/edac.h>
+#include <linux/ktime.h>
+ * Hardware Events Report
+ *
+ * Those events are generated when hardware detected a corrected or
+ * uncorrected event, and are meant to replace the current API to report
+ * errors defined on both EDAC and MCE subsystems.
+ *
+ * FIXME: Add events for handling memory errors originated from the
+ * MCE subsystem.
+ */
+ * Hardware-independent Memory Controller specific events
+ */
+ * Default error mechanisms for Memory Controller errors (CE and UE)
+ */
+ TP_PROTO(const unsigned int err_type,
+ const unsigned int mc_index,
+ const char *error_msg,
+ const char *label,
+ const char *location,
+ const char *core_detail,
+ const char *driver_detail),
+ TP_ARGS(err_type, mc_index, error_msg, label, location,
+ core_detail, driver_detail),
+ TP_STRUCT__entry(
+ __field( unsigned int, err_type )
+ __field( unsigned int, mc_index )
+ __string( msg, error_msg )
+ __string( label, label )
+ __string( detail, core_detail )
+ __string( location, location )
+ __string( driver_detail, driver_detail )
+ ),
+ TP_fast_assign(
+ __entry->err_type = err_type;
+ __entry->mc_index = mc_index;
+ __assign_str(msg, error_msg);
+ __assign_str(label, label);
+ __assign_str(location, location);
+ __assign_str(detail, core_detail);
+ __assign_str(driver_detail, driver_detail);
+ ),
+ TP_printk("%s error:%s on memory stick \"%s\" (mc:%d %s %s %s)",
+ (__entry->err_type == HW_EVENT_ERR_CORRECTED) ? "Corrected" :
+ ((__entry->err_type == HW_EVENT_ERR_FATAL) ?
+ "Fatal" : "Uncorrected"),
+ __get_str(msg),
+ __get_str(label),
+ __entry->mc_index,
+ __get_str(location),
+ __get_str(detail),
+ __get_str(driver_detail))
+#endif /* _TRACE_HW_EVENT_MC_H */
+/* This part must be outside protection */
+#include <trace/define_trace.h>

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