| Message ID | 20211208160907.749482-1-james.clark@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] coresight: Add config flag to enable branch broadcast | expand |
On 08/12/2021 16:09, James Clark wrote: > When enabled, all taken branch addresses are output, even if the branch > was because of a direct branch instruction. This enables reconstruction > of the program flow without having access to the memory image of the > code being executed. > > Use bit 8 for the config option which would be the correct bit for > programming ETMv3. Although branch broadcast can't be enabled on ETMv3 > because it's not in the define ETM3X_SUPPORTED_OPTIONS, using the > correct bit might help prevent future collisions or allow it to be > enabled if needed. > > Signed-off-by: James Clark <james.clark@arm.com> > --- > drivers/hwtracing/coresight/coresight-etm-perf.c | 2 ++ > drivers/hwtracing/coresight/coresight-etm4x-core.c | 9 +++++++++ > include/linux/coresight-pmu.h | 2 ++ > 3 files changed, 13 insertions(+) > > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c > index c039b6ae206f..43bbd5dc3d3b 100644 > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c > @@ -52,6 +52,7 @@ static DEFINE_PER_CPU(struct coresight_device *, csdev_src); > * The PMU formats were orignally for ETMv3.5/PTM's ETMCR 'config'; > * now take them as general formats and apply on all ETMs. > */ > +PMU_FORMAT_ATTR(branch_broadcast, "config:"__stringify(ETM_OPT_BRANCH_BROADCAST)); > PMU_FORMAT_ATTR(cycacc, "config:" __stringify(ETM_OPT_CYCACC)); > /* contextid1 enables tracing CONTEXTIDR_EL1 for ETMv4 */ > PMU_FORMAT_ATTR(contextid1, "config:" __stringify(ETM_OPT_CTXTID)); > @@ -97,6 +98,7 @@ static struct attribute *etm_config_formats_attr[] = { > &format_attr_sinkid.attr, > &format_attr_preset.attr, > &format_attr_configid.attr, > + &format_attr_branch_broadcast.attr, > NULL, > }; > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c > index bf18128cf5de..d2bafb50c66a 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c > @@ -692,6 +692,15 @@ static int etm4_parse_event_config(struct coresight_device *csdev, > ret = cscfg_csdev_enable_active_config(csdev, cfg_hash, preset); > } > > + /* branch broadcast - enable if selected and supported */ > + if (attr->config & BIT(ETM_OPT_BRANCH_BROADCAST)) { > + if (!drvdata->trcbb) { > + ret = -EINVAL; > + goto out; > + } else > + config->cfg |= BIT(ETM4_CFG_BIT_BB); nit: For consistent styling, I would recommend to wrap the else case also in { }. Otherwise looks good to me. Suzuki
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index c039b6ae206f..43bbd5dc3d3b 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -52,6 +52,7 @@ static DEFINE_PER_CPU(struct coresight_device *, csdev_src); * The PMU formats were orignally for ETMv3.5/PTM's ETMCR 'config'; * now take them as general formats and apply on all ETMs. */ +PMU_FORMAT_ATTR(branch_broadcast, "config:"__stringify(ETM_OPT_BRANCH_BROADCAST)); PMU_FORMAT_ATTR(cycacc, "config:" __stringify(ETM_OPT_CYCACC)); /* contextid1 enables tracing CONTEXTIDR_EL1 for ETMv4 */ PMU_FORMAT_ATTR(contextid1, "config:" __stringify(ETM_OPT_CTXTID)); @@ -97,6 +98,7 @@ static struct attribute *etm_config_formats_attr[] = { &format_attr_sinkid.attr, &format_attr_preset.attr, &format_attr_configid.attr, + &format_attr_branch_broadcast.attr, NULL, }; diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index bf18128cf5de..d2bafb50c66a 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -692,6 +692,15 @@ static int etm4_parse_event_config(struct coresight_device *csdev, ret = cscfg_csdev_enable_active_config(csdev, cfg_hash, preset); } + /* branch broadcast - enable if selected and supported */ + if (attr->config & BIT(ETM_OPT_BRANCH_BROADCAST)) { + if (!drvdata->trcbb) { + ret = -EINVAL; + goto out; + } else + config->cfg |= BIT(ETM4_CFG_BIT_BB); + } + out: return ret; } diff --git a/include/linux/coresight-pmu.h b/include/linux/coresight-pmu.h index 4ac5c081af93..6c2fd6cc5a98 100644 --- a/include/linux/coresight-pmu.h +++ b/include/linux/coresight-pmu.h @@ -18,6 +18,7 @@ * ETMv3.5/PTM doesn't define ETMCR config bits with prefix "ETM3_" and * directly use below macros as config bits. */ +#define ETM_OPT_BRANCH_BROADCAST 8 #define ETM_OPT_CYCACC 12 #define ETM_OPT_CTXTID 14 #define ETM_OPT_CTXTID2 15 @@ -25,6 +26,7 @@ #define ETM_OPT_RETSTK 29 /* ETMv4 CONFIGR programming bits for the ETM OPTs */ +#define ETM4_CFG_BIT_BB 3 #define ETM4_CFG_BIT_CYCACC 4 #define ETM4_CFG_BIT_CTXTID 6 #define ETM4_CFG_BIT_VMID 7
When enabled, all taken branch addresses are output, even if the branch was because of a direct branch instruction. This enables reconstruction of the program flow without having access to the memory image of the code being executed. Use bit 8 for the config option which would be the correct bit for programming ETMv3. Although branch broadcast can't be enabled on ETMv3 because it's not in the define ETM3X_SUPPORTED_OPTIONS, using the correct bit might help prevent future collisions or allow it to be enabled if needed. Signed-off-by: James Clark <james.clark@arm.com> --- drivers/hwtracing/coresight/coresight-etm-perf.c | 2 ++ drivers/hwtracing/coresight/coresight-etm4x-core.c | 9 +++++++++ include/linux/coresight-pmu.h | 2 ++ 3 files changed, 13 insertions(+)