| Message ID | 20220610133431.410514-1-kjain@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc/papr_scm: Fix nvdimm event mappings | expand |
Hi Kajol, A few comments below ... Kajol Jain <kjain@linux.ibm.com> writes: > Commit 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support") > adds performance monitoring support for papr-scm nvdimm devices via ^ We're talking about a commit that's already happened so we should use past tense, so "added". > perf interface. It also adds one array in papr_scm_priv "added" > 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. ^ "returned by the hypervisor." To make it clear where the stat buffer comes from, and that it's out of our control. > The assumption may not be true or documented as part of PAPR > documentation. That reads as the assumption "may not be documented as part of PAPR". I think what you mean is the assumption *is not* documented by PAPR, and although it happens to be true on current systems it may not be true in future. > Fixing it, by adding a static mapping for nvdimm events to Fix it > 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@linux.ibm.com> > Signed-off-by: Kajol Jain <kjain@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 > @@ -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", > +}; The order of the strings in that array becomes ABI. Because it defines the mapping from perf_event.attr.config (perf user ABI) to the actual event we request from the hypervisor. So I'd like that made more explicit by using designated initialisers, eg: static const char * const nvdimm_events_map[] = { [1] = "CtlResCt", [2] = "CtlResTm", ... That way an accidental reordering of the array won't break anything. You shouldn't need to specify 0 either as it's not used. > @@ -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)); It's not clear that this won't index off the end of the array. There is a check in papr_scm_pmu_event_init(), but I'd probably be happier if we did an explicit check in here as well, eg: if (event->attr.config >= ARRAY_SIZE(nvdimm_events_map)) return -EINVAL; > 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; You shouldn't need to initialise rc here. It's not used until the call to drc_pmem_query_stats() below. > 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; > } cheers
On 6/27/22 12:05, Michael Ellerman wrote: > Hi Kajol, > > A few comments below ... Hi Michael, Thanks for reviewing the patch. I will make the changes suggested by you and send version 2 of this patch. Thanks, Kajol Jain > > Kajol Jain <kjain@linux.ibm.com> writes: >> Commit 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support") >> adds performance monitoring support for papr-scm nvdimm devices via > ^ > We're talking about a commit that's already happened so we should use > past tense, so "added". > >> perf interface. It also adds one array in papr_scm_priv > "added" >> 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. > ^ > "returned by the hypervisor." > > To make it clear where the stat buffer comes from, and that it's out of > our control. > >> The assumption may not be true or documented as part of PAPR >> documentation. > > That reads as the assumption "may not be documented as part of PAPR". I > think what you mean is the assumption *is not* documented by PAPR, and > although it happens to be true on current systems it may not be true in > future. > >> Fixing it, by adding a static mapping for nvdimm events to > Fix it >> 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@linux.ibm.com> >> Signed-off-by: Kajol Jain <kjain@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 >> @@ -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", >> +}; > > The order of the strings in that array becomes ABI. Because it defines > the mapping from perf_event.attr.config (perf user ABI) to the actual > event we request from the hypervisor. > > So I'd like that made more explicit by using designated initialisers, eg: > > static const char * const nvdimm_events_map[] = { > [1] = "CtlResCt", > [2] = "CtlResTm", > ... > > That way an accidental reordering of the array won't break anything. Yes make sense. Will do update it. > > You shouldn't need to specify 0 either as it's not used. > >> @@ -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)); > > It's not clear that this won't index off the end of the array. > > There is a check in papr_scm_pmu_event_init(), but I'd probably be > happier if we did an explicit check in here as well, eg: > > if (event->attr.config >= ARRAY_SIZE(nvdimm_events_map)) > return -EINVAL; > > >> 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; > > You shouldn't need to initialise rc here. It's not used until the call > to drc_pmem_query_stats() below. Ok sure. > >> 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; >> } > > cheers
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);
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@linux.ibm.com> Signed-off-by: Kajol Jain <kjain@linux.ibm.com> --- arch/powerpc/platforms/pseries/papr_scm.c | 59 ++++++++++------------- 1 file changed, 25 insertions(+), 34 deletions(-)