[PATCH] powerpc/papr_scm: Fix nvdimm event mappings

[Kajol Jain]

Commit 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support")
adds performance monitoring support for papr-scm nvdimm devices via
perf interface. It also adds one array in papr_scm_priv
structure called "nvdimm_events_map", to dynamically save the stat_id
for events specified in nvdimm driver code "nd_perf.c".

Right now the mapping is done based on the result of 
H_SCM_PERFORMANCE_STATS hcall, when all the stats are
requested. Currently there is an assumption, that a
certain stat will always be found at a specific offset
in the stat buffer. The assumption may not be true or
documented as part of PAPR documentation. Fixing it,
by adding a static mapping for nvdimm events to
corresponding stat-id, and removing the map from
papr_scm_priv structure.

Fixes: 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support")
Reported-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
Signed-off-by: Kajol Jain <kjain at linux.ibm.com>
---
 arch/powerpc/platforms/pseries/papr_scm.c | 59 ++++++++++-------------
 1 file changed, 25 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 181b855b3050..5434c654a797 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -124,9 +124,6 @@ struct papr_scm_priv {
 
 	/* The bits which needs to be overridden */
 	u64 health_bitmap_inject_mask;
-
-	/* array to have event_code and stat_id mappings */
-	u8 *nvdimm_events_map;
 };
 
 static int papr_scm_pmem_flush(struct nd_region *nd_region,
@@ -350,6 +347,26 @@ static ssize_t drc_pmem_query_stats(struct papr_scm_priv *p,
 #ifdef CONFIG_PERF_EVENTS
 #define to_nvdimm_pmu(_pmu)	container_of(_pmu, struct nvdimm_pmu, pmu)
 
+static const char * const nvdimm_events_map[] = {
+	"N/A",
+	"CtlResCt",
+	"CtlResTm",
+	"PonSecs ",
+	"MemLife ",
+	"CritRscU",
+	"HostLCnt",
+	"HostSCnt",
+	"HostSDur",
+	"HostLDur",
+	"MedRCnt ",
+	"MedWCnt ",
+	"MedRDur ",
+	"MedWDur ",
+	"CchRHCnt",
+	"CchWHCnt",
+	"FastWCnt",
+};
+
 static int papr_scm_pmu_get_value(struct perf_event *event, struct device *dev, u64 *count)
 {
 	struct papr_scm_perf_stat *stat;
@@ -361,7 +378,7 @@ static int papr_scm_pmu_get_value(struct perf_event *event, struct device *dev,
 	size = sizeof(struct papr_scm_perf_stats) +
 		sizeof(struct papr_scm_perf_stat);
 
-	if (!p || !p->nvdimm_events_map)
+	if (!p)
 		return -EINVAL;
 
 	stats = kzalloc(size, GFP_KERNEL);
@@ -370,7 +387,7 @@ static int papr_scm_pmu_get_value(struct perf_event *event, struct device *dev,
 
 	stat = &stats->scm_statistic[0];
 	memcpy(&stat->stat_id,
-	       &p->nvdimm_events_map[event->attr.config * sizeof(stat->stat_id)],
+	       nvdimm_events_map[event->attr.config],
 		sizeof(stat->stat_id));
 	stat->stat_val = 0;
 
@@ -460,10 +477,9 @@ static void papr_scm_pmu_del(struct perf_event *event, int flags)
 
 static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu *nd_pmu)
 {
-	struct papr_scm_perf_stat *stat;
 	struct papr_scm_perf_stats *stats;
 	u32 available_events;
-	int index, rc = 0;
+	int rc = 0;
 
 	available_events = (p->stat_buffer_len  - sizeof(struct papr_scm_perf_stats))
 			/ sizeof(struct papr_scm_perf_stat);
@@ -473,34 +489,12 @@ static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu
 	/* Allocate the buffer for phyp where stats are written */
 	stats = kzalloc(p->stat_buffer_len, GFP_KERNEL);
 	if (!stats) {
-		rc = -ENOMEM;
-		return rc;
+		return -ENOMEM;
 	}
 
 	/* Called to get list of events supported */
 	rc = drc_pmem_query_stats(p, stats, 0);
-	if (rc)
-		goto out;
 
-	/*
-	 * Allocate memory and populate nvdimm_event_map.
-	 * Allocate an extra element for NULL entry
-	 */
-	p->nvdimm_events_map = kcalloc(available_events + 1,
-				       sizeof(stat->stat_id),
-				       GFP_KERNEL);
-	if (!p->nvdimm_events_map) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
-	/* Copy all stat_ids to event map */
-	for (index = 0, stat = stats->scm_statistic;
-	     index < available_events; index++, ++stat) {
-		memcpy(&p->nvdimm_events_map[index * sizeof(stat->stat_id)],
-		       &stat->stat_id, sizeof(stat->stat_id));
-	}
-out:
 	kfree(stats);
 	return rc;
 }
@@ -536,7 +530,7 @@ static void papr_scm_pmu_register(struct papr_scm_priv *p)
 
 	rc = register_nvdimm_pmu(nd_pmu, p->pdev);
 	if (rc)
-		goto pmu_register_err;
+		goto pmu_check_events_err;
 
 	/*
 	 * Set archdata.priv value to nvdimm_pmu structure, to handle the
@@ -545,8 +539,6 @@ static void papr_scm_pmu_register(struct papr_scm_priv *p)
 	p->pdev->archdata.priv = nd_pmu;
 	return;
 
-pmu_register_err:
-	kfree(p->nvdimm_events_map);
 pmu_check_events_err:
 	kfree(nd_pmu);
 pmu_err_print:
@@ -1557,7 +1549,6 @@ static int papr_scm_remove(struct platform_device *pdev)
 		unregister_nvdimm_pmu(pdev->archdata.priv);
 
 	pdev->archdata.priv = NULL;
-	kfree(p->nvdimm_events_map);
 	kfree(p->bus_desc.provider_name);
 	kfree(p);
 
-- 
2.31.1