coresight: etm4x: adding configurable address range filtering

This patch adds the capability to specify address ranges from
the perf cmd line using the --filter option.  If the IP
falls within the range(s) program flow traces are generated.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 119 insertions, 9 deletions

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index 1044ed609d81..ebaefb45130f 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -45,7 +45,9 @@ module_param_named(boot_enable, boot_enable, int, S_IRUGO);
 /* The number of ETMv4 currently registered */
 static int etm4_count;
 static struct etmv4_drvdata *etmdrvdata[NR_CPUS];
-static void etm4_set_default(struct etmv4_config *config);
+static void etm4_set_default_config(struct etmv4_config *config);
+static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
+                                  struct perf_event *event);
 
 static enum cpuhp_state hp_online;
 
@@ -187,11 +189,14 @@ static void etm4_enable_hw(void *info)
 static int etm4_parse_event_config(struct etmv4_drvdata *drvdata,
                                    struct perf_event *event)
 {
+        int ret = 0;
         struct etmv4_config *config = &drvdata->config;
         struct perf_event_attr *attr = &event->attr;
 
-        if (!attr)
-                return -EINVAL;
+        if (!attr) {
+                ret = -EINVAL;
+                goto out;
+        }
 
         /* Clear configuration from previous run */
         memset(config, 0, sizeof(struct etmv4_config));
@@ -203,7 +208,12 @@ static int etm4_parse_event_config(struct etmv4_drvdata *drvdata,
                 config->mode = ETM_MODE_EXCL_USER;
 
         /* Always start from the default config */
-        etm4_set_default(config);
+        etm4_set_default_config(config);
+
+        /* Configure filters specified on the perf cmd line, if any. */
+        ret = etm4_set_event_filters(drvdata, event);
+        if (ret)
+                goto out;
 
         /* Go from generic option to ETMv4 specifics */
         if (attr->config & BIT(ETM_OPT_CYCACC))
@@ -211,23 +221,30 @@ static int etm4_parse_event_config(struct etmv4_drvdata *drvdata,
         if (attr->config & BIT(ETM_OPT_TS))
                 config->cfg |= ETMv4_MODE_TIMESTAMP;
 
-        return 0;
+out:
+        return ret;
 }
 
 static int etm4_enable_perf(struct coresight_device *csdev,
                             struct perf_event *event)
 {
+        int ret = 0;
         struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
-        if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
-                return -EINVAL;
+        if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id())) {
+                ret = -EINVAL;
+                goto out;
+        }
 
         /* Configure the tracer based on the session's specifics */
-        etm4_parse_event_config(drvdata, event);
+        ret = etm4_parse_event_config(drvdata, event);
+        if (ret)
+                goto out;
         /* And enable it */
         etm4_enable_hw(drvdata);
 
-        return 0;
+out:
+        return ret;
 }
 
 static int etm4_enable_sysfs(struct coresight_device *csdev)
@@ -682,6 +699,99 @@ static void etm4_set_default(struct etmv4_config *config)
         etm4_set_default_filter(config);
 }
 
+static int etm4_get_next_comparator(struct etmv4_drvdata *drvdata, u32 type)
+{
+        int nr_comparator, index = 0;
+        struct etmv4_config *config = &drvdata->config;
+
+        /*
+         * nr_addr_cmp holds the number of comparator _pair_, so time 2
+         * for the total number of comparators.
+         */
+        nr_comparator = drvdata->nr_addr_cmp * 2;
+
+        /* Go through the tally of comparators looking for a free one. */
+        while (index < nr_comparator) {
+                switch (type) {
+                case ETM_ADDR_TYPE_RANGE:
+                        if (config->addr_type[index] == ETM_ADDR_TYPE_NONE &&
+                            config->addr_type[index + 1] == ETM_ADDR_TYPE_NONE)
+                                return index;
+
+                        /* Address range comparators go in pairs */
+                        index += 2;
+                        break;
+                default:
+                        return -EINVAL;
+                }
+        }
+
+        /* If we are here all the comparators have been used. */
+        return -ENOSPC;
+}
+
+static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
+                                  struct perf_event *event)
+{
+        int i, comparator, ret = 0;
+        struct etmv4_config *config = &drvdata->config;
+        struct etm_filters *filters = event->hw.addr_filters;
+
+        if (!filters)
+                goto default_filter;
+
+        /* Sync events with what Perf got */
+        perf_event_addr_filters_sync(event);
+
+        /*
+         * If there are no filters to deal with simply go ahead with
+         * the default filter, i.e the entire address range.
+         */
+        if (!filters->nr_filters)
+                goto default_filter;
+
+        for (i = 0; i < filters->nr_filters; i++) {
+                struct etm_filter *filter = &filters->etm_filter[i];
+                enum etm_addr_type type = filter->type;
+
+                /* See if a comparator is free. */
+                comparator = etm4_get_next_comparator(drvdata, type);
+                if (comparator < 0) {
+                        ret = comparator;
+                        goto out;
+                }
+
+                switch (type) {
+                case ETM_ADDR_TYPE_RANGE:
+                        etm4_set_comparator_filter(config,
+                                                   filter->start_addr,
+                                                   filter->stop_addr,
+                                                   comparator);
+                        /*
+                         * TRCVICTLR::SSSTATUS == 1, the start-stop logic is
+                         * in the started state
+                         */
+                        config->vinst_ctrl |= BIT(9);
+
+                        /* No start-stop filtering for ViewInst */
+                        config->vissctlr = 0x0;
+                        break;
+                default:
+                        ret = -EINVAL;
+                        goto out;
+                }
+        }
+
+        goto out;
+
+
+default_filter:
+        etm4_set_default_filter(config);
+
+out:
+        return ret;
+}
+
 void etm4_config_trace_mode(struct etmv4_config *config)
 {
         u32 addr_acc, mode;