[PATCH v2 3/6] powerpc/powernv: Detect supported IMA units and its events

[Hemant Kumar]

Parse device tree to detect IMA units. Traverse through each IMA unit
node to find supported events and corresponding unit/scale files (if any).

Right now, only nest IMA units are supported.
The nest IMA unit event node from device tree will contain the offset in
the reserved memory region to get the counter data for a given
event. The offsets for the nest events are contained in the "reg"
property of the event "node".

Kernel code uses this offset as event configuration value.

Device tree parser code also looks for scale/unit property in the event
node and passes on the value as an event attr for perf interface to use
in the post processing by the perf tool. Some PMUs may have common scale
and unit properties which implies that all events supported by this PMU
inherit the scale and unit properties of the PMU itself. For those
events, we need to set the common unit and scale values.

For failure to initialize any unit or any event, disable that unit and
continue setting up the rest of them.

Cc: Madhavan Srinivasan <maddy@xxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Anton Blanchard <anton@xxxxxxxxx>
Cc: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Cc: Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Signed-off-by: Hemant Kumar <hemant@xxxxxxxxxxxxxxxxxx>
---
Changelog :
v1 -> v2:
 - Read from the "event-name" property instead of "name" property for
   an event node.
 - Assign scale and unit values for events for a PMU which has a common
   unit and scale value.

 arch/powerpc/platforms/powernv/opal-ima.c | 332 ++++++++++++++++++++++++++++++
 1 file changed, 332 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/opal-ima.c b/arch/powerpc/platforms/powernv/opal-ima.c
index 446e7bc..e8d5771 100644
--- a/arch/powerpc/platforms/powernv/opal-ima.c
+++ b/arch/powerpc/platforms/powernv/opal-ima.c
@@ -32,6 +32,337 @@
 #include <asm/ima-pmu.h>
 
 struct perchip_nest_info nest_perchip_info[IMA_MAX_CHIPS];
+struct ima_pmu *per_nest_pmu_arr[IMA_MAX_PMUS];
+
+static int ima_event_info(char *name, struct ima_events *events)
+{
+	char *buf;
+
+	/* memory for content */
+	buf = kzalloc(IMA_MAX_PMU_NAME_LEN, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	events->ev_name = name;
+	events->ev_value = buf;
+	return 0;
+}
+
+static int ima_event_info_str(struct property *pp, char *name,
+			       struct ima_events *events)
+{
+	int ret;
+
+	ret = ima_event_info(name, events);
+	if (ret)
+		return ret;
+
+	if (!pp->value || (strnlen(pp->value, pp->length) == pp->length) ||
+	   (pp->length > IMA_MAX_PMU_NAME_LEN))
+		return -EINVAL;
+	strncpy(events->ev_value, (const char *)pp->value, pp->length);
+
+	return 0;
+}
+
+static int ima_event_info_val(char *name, u32 val,
+			       struct ima_events *events)
+{
+	int ret;
+
+	ret = ima_event_info(name, events);
+	if (ret)
+		return ret;
+	sprintf(events->ev_value, "event=0x%x", val);
+
+	return 0;
+}
+
+static int set_event_property(struct property *pp, char *event_prop,
+			      struct ima_events *events, char *ev_name)
+{
+	char *buf;
+	int ret;
+
+	buf = kzalloc(IMA_MAX_PMU_NAME_LEN, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	sprintf(buf, "%s.%s", ev_name, event_prop);
+	ret = ima_event_info_str(pp, buf, events);
+	if (ret) {
+		kfree(events->ev_name);
+		kfree(events->ev_value);
+	}
+
+	return ret;
+}
+
+/*
+ * ima_events_node_parser: Parse the event node "dev" and assign the parsed
+ *                         information to event "events".
+ *
+ * Parses the "reg" property of this event. "reg" gives us the event offset.
+ * Also, parse the "scale" and "unit" properties, if any.
+ */
+static int ima_events_node_parser(struct device_node *dev,
+				  struct ima_events *events,
+				  struct property *event_scale,
+				  struct property *event_unit)
+{
+	struct property *name, *pp;
+	char *ev_name;
+	u32 val;
+	int idx = 0, ret;
+
+	if (!dev)
+		return -EINVAL;
+
+	/*
+	 * Loop through each property of an event node
+	 */
+	name = of_find_property(dev, "event-name", NULL);
+	if (!name)
+		return -ENODEV;
+
+	if (!name->value ||
+	  (strnlen(name->value, name->length) == name->length) ||
+	  (name->length > IMA_MAX_PMU_NAME_LEN))
+		return -EINVAL;
+
+	ev_name = kzalloc(IMA_MAX_PMU_NAME_LEN, GFP_KERNEL);
+	if (!ev_name)
+		return -ENOMEM;
+
+	strncpy(ev_name, name->value, name->length);
+
+	/*
+	 * Parse each property of this event node "dev". Property "reg" has
+	 * the offset which is assigned to the event name. Other properties
+	 * like "scale" and "unit" are assigned to event.scale and event.unit
+	 * accordingly.
+	 */
+	for_each_property_of_node(dev, pp) {
+		/*
+		 * If there is an issue in parsing a single property of
+		 * this event, we just clean up the buffers, but we still
+		 * continue to parse.
+		 */
+		if (strncmp(pp->name, "reg", 3) == 0) {
+			of_property_read_u32(dev, pp->name, &val);
+			ret = ima_event_info_val(ev_name, val, &events[idx]);
+			if (ret) {
+				kfree(events[idx].ev_name);
+				kfree(events[idx].ev_value);
+				continue;
+			}
+			/*
+			 * If the common scale and unit properties available,
+			 * then, assign them to this event
+			 */
+			if (event_scale) {
+				idx++;
+				ret = set_event_property(event_scale, "scale",
+							 &events[idx],
+							 ev_name);
+				if (ret)
+					continue;
+				idx++;
+			}
+			if (event_unit) {
+				ret = set_event_property(event_unit, "unit",
+							 &events[idx],
+							 ev_name);
+				if (ret)
+					continue;
+			}
+			idx++;
+		} else if (strncmp(pp->name, "unit", 4) == 0) {
+			ret = set_event_property(pp, "unit", &events[idx],
+						 ev_name);
+			if (ret)
+				continue;
+			idx++;
+		} else if (strncmp(pp->name, "scale", 5) == 0) {
+			ret = set_event_property(pp, "scale", &events[idx],
+						 ev_name);
+			if (ret)
+				continue;
+			idx++;
+		}
+	}
+
+	return idx;
+}
+
+/*
+ * ima_get_domain : Returns the domain for pmu "pmu_dev".
+ */
+int ima_get_domain(struct device_node *pmu_dev)
+{
+	if (of_device_is_compatible(pmu_dev, IMA_DTB_NEST_COMPAT))
+		return IMA_DOMAIN_NEST;
+	else
+		return UNKNOWN_DOMAIN;
+}
+
+/*
+ * get_nr_children : Returns the number of children for a pmu device node.
+ */
+static int get_nr_children(struct device_node *pmu_node)
+{
+	struct device_node *child;
+	int i = 0;
+
+	for_each_child_of_node(pmu_node, child)
+		i++;
+	return i;
+}
+
+/*
+ * ima_free_events : Cleanup the "events" list having "nr_entries" entries.
+ */
+static void ima_free_events(struct ima_events *events, int nr_entries)
+{
+	int i;
+
+	/* Nothing to clean, return */
+	if (!events)
+		return;
+	for (i = 0; i < nr_entries; i++) {
+		kfree(events[i].ev_name);
+		kfree(events[i].ev_value);
+	}
+
+	kfree(events);
+}
+
+/*
+ * ima_pmu_create : Takes the parent device which is the pmu unit and a
+ *                  pmu_index as the inputs.
+ * Allocates memory for the pmu, sets up its domain (NEST or CORE), and
+ * allocates memory for the events supported by this pmu. Assigns a name for
+ * the pmu. Calls ima_events_node_parser() to setup the individual events.
+ * If everything goes fine, it calls, init_ima_pmu() to setup the pmu device
+ * and register it.
+ */
+static int ima_pmu_create(struct device_node *parent, int pmu_index)
+{
+	struct device_node *ev_node;
+	struct ima_events *events;
+	struct ima_pmu *pmu_ptr;
+	struct property *pp, *scale_pp, *unit_pp;
+	char *buf;
+	int idx = 0, ret, nr_children = 0;
+
+	if (!parent)
+		return -EINVAL;
+
+	/* memory for pmu */
+	pmu_ptr = kzalloc(sizeof(struct ima_pmu), GFP_KERNEL);
+	if (!pmu_ptr)
+		return -ENOMEM;
+
+	pmu_ptr->domain = ima_get_domain(parent);
+	if (pmu_ptr->domain == UNKNOWN_DOMAIN)
+		goto free_pmu;
+
+	/* Needed for hotplug/migration */
+	per_nest_pmu_arr[pmu_index] = pmu_ptr;
+
+	/*
+	 * Get the maximum no. of events in this node.
+	 * Multiply by 3 to account for .scale and .unit properties
+	 * This number suggests the amount of memory needed to setup the
+	 * events for this pmu.
+	 */
+	nr_children = get_nr_children(parent) * 3;
+
+	/* memory for pmu events */
+	events = kzalloc((sizeof(struct ima_events) * nr_children),
+			 GFP_KERNEL);
+	if (!events) {
+		ret = -ENOMEM;
+		goto free_pmu;
+	}
+
+	pp = of_find_property(parent, "name", NULL);
+	if (!pp) {
+		ret = -ENODEV;
+		goto free_events;
+	}
+
+	if (!pp->value ||
+	  (strnlen(pp->value, pp->length) == pp->length) ||
+	    (pp->length > IMA_MAX_PMU_NAME_LEN)) {
+		ret = -EINVAL;
+		goto free_events;
+	}
+
+	buf = kzalloc(IMA_MAX_PMU_NAME_LEN, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto free_events;
+	}
+
+	/* Save the name to register it later */
+	sprintf(buf, "nest_%s", (char *)pp->value);
+	pmu_ptr->pmu.name = (char *)buf;
+
+	/*
+	 * Check if there is a common "scale" and "unit" properties inside
+	 * the PMU node for all the events supported by this PMU.
+	 */
+	scale_pp = of_find_property(parent, "scale", NULL);
+	unit_pp = of_find_property(parent, "unit", NULL);
+
+	/* Loop through event nodes */
+	for_each_child_of_node(parent, ev_node) {
+		ret = ima_events_node_parser(ev_node, &events[idx], scale_pp,
+					     unit_pp);
+		if (ret < 0) {
+			/* Unable to parse this event */
+			if (ret == -ENOMEM)
+				goto free_events;
+			continue;
+		}
+
+		/*
+		 * ima_event_node_parser will return number of
+		 * event entries created for this. This could include
+		 * event scale and unit files also.
+		 */
+		idx += ret;
+	}
+
+	return 0;
+
+free_events:
+	ima_free_events(events, idx);
+free_pmu:
+	kfree(pmu_ptr);
+	return ret;
+}
+
+/*
+ * ima_pmu_setup : Setup the IMA PMUs (children of "parent").
+ */
+static void ima_pmu_setup(struct device_node *parent)
+{
+	struct device_node *child;
+	int pmu_count = 0, rc = 0;
+
+	if (!parent)
+		return;
+
+	/* Setup all the IMA pmus */
+	for_each_child_of_node(parent, child) {
+		ima_pmu_create(child, pmu_count);
+		if (rc)
+			return;
+		pmu_count++;
+	}
+}
 
 static int opal_ima_counters_probe(struct platform_device *pdev)
 {
@@ -93,6 +424,7 @@ static int opal_ima_counters_probe(struct platform_device *pdev)
 		} while (i < (pcni->size / PAGE_SIZE));
 	}
 
+	ima_pmu_setup(ima_dev);
 	return 0;
 err:
 	return -ENODEV;
-- 
2.7.4