Messages in this thread | | | Date | Thu, 9 Dec 2021 09:21:20 +0000 | Subject | Re: [PATCH 1/3] coresight: Add config flag to enable branch broadcast | From | Suzuki K Poulose <> |
| |
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
| |