perf: make Arm CCI driver modular

PATCH New Robin Murphy 1 participant 4 messages May 14, 2018 Arm PMU profiling and debugging

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Robin Murphy

author

2018-05-14 13:34 UTC #0 lore raw

v2 cover perf: make Arm CCI driver modular

Now that it has been surgically removed from the MCPM port-control code, we can let the CCI PMU driver be modular. Probing the PMU in the first place still depends on the bus driver stub being built-in, but it's a small price to pay compared to the major upheaval of completely reworking the DT-handling code across the two drivers.

Robin.

v2: Fix Kconfig dependencies per kbuild robot report

Robin Murphy (3):
perf/arm-cc*: Fix MODULE_LICENSE() tags
perf/arm-cci: Remove pointless PMU disabling
perf/arm-cci: Allow building as a module

 drivers/perf/Kconfig   | 34 ++++++++++++++++++----------------
 drivers/perf/arm-cci.c | 32 ++++++++++++++++++++------------
 drivers/perf/arm-ccn.c |  2 +-
 3 files changed, 39 insertions(+), 29 deletions(-)

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2.17.0.dirty

Robin Murphy

author

2018-05-14 13:34 UTC #1 lore raw

PATCH v2 1/3 perf/arm-cc*: Fix MODULE_LICENSE() tags

The CCI/CCN drivers are licensed under GPLv2, but the MODULE_LICENSE() tags are using the bare "GPL" string implying GPLv2 or later. Fix them to match their actual file license.

Acked-by Pawel Moll <[email protected]>

Acked-by Suzuki K Poulose <[email protected]>

Signed-off-by Robin Murphy <[email protected]>

---

v2: No change

 drivers/perf/arm-cci.c | 2 +-
 drivers/perf/arm-ccn.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

drivers/perf/arm-cci.c +1 -1

index 383b2d3dcbc6..53c774b20563 100644
@@ -1718,5 +1718,5 @@ static struct platform_driver cci_pmu_driver = {
 };
 
 builtin_platform_driver(cci_pmu_driver);
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("ARM CCI PMU support");

drivers/perf/arm-ccn.c +1 -1

index 65b7e4042ece..917b47e776df 100644
@@ -1594,4 +1594,4 @@ module_init(arm_ccn_init);
 module_exit(arm_ccn_exit);
 
 MODULE_AUTHOR("Pawel Moll <[email protected]>");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");

Signature · 1 line

2.17.0.dirty

Robin Murphy

author

2018-05-14 13:34 UTC #2 lore raw

PATCH v2 2/3 perf/arm-cci: Remove pointless PMU disabling

In reply to Robin Murphy

The CCI PMU driver bears some legacy remnants of the arm_pmu framework from when it was split in c6f85cb4305b ("bus: cci: move away from arm_pmu framework"). In particular this perf_pmu_{dis,en}able() dance around pmu->add which was fixed for arm_pmu in a9e469d1c89b ("drivers/perf: arm_pmu: remove pointless PMU disabling").

For the exact same reasons (i.e. perf core already does this around the call anyway), give cci_pmu_add() the exact same change, which also prevents having to export those core functions to build it as a module.

Acked-by Mark Rutland <[email protected]>

Signed-off-by Robin Murphy <[email protected]>

---

v2: Add Mark's ack

 drivers/perf/arm-cci.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

drivers/perf/arm-cci.c +3 ~~-10~~

index 53c774b20563..7029d8fe8f44 100644
@@ -1184,16 +1184,11 @@ static int cci_pmu_add(struct perf_event *event, int flags)
 	struct cci_pmu_hw_events *hw_events = &cci_pmu->hw_events;
 	struct hw_perf_event *hwc = &event->hw;
 	int idx;
-	int err = 0;
-
-	perf_pmu_disable(event->pmu);
 
 	/* If we don't have a space for the counter then finish early. */
 	idx = pmu_get_event_idx(hw_events, event);
-	if (idx < 0) {
-		err = idx;
-		goto out;
-	}
+	if (idx < 0)
+		return idx;
 
 	event->hw.idx = idx;
 	hw_events->events[idx] = event;

@@ -1205,9 +1200,7 @@ static int cci_pmu_add(struct perf_event *event, int flags)
 	/* Propagate our changes to the userspace mapping. */
 	perf_event_update_userpage(event);
 
-out:
-	perf_pmu_enable(event->pmu);
-	return err;
+	return 0;
 }
 
 static void cci_pmu_del(struct perf_event *event, int flags)

Signature · 1 line

2.17.0.dirty

Robin Murphy

author

2018-05-14 13:34 UTC #3 lore raw

PATCH v2 3/3 perf/arm-cci: Allow building as a module

In reply to Robin Murphy

Fill in the few extra bits and annotations needed to make the driver work properly as a module, and jiggle the Kconfig to expose the driver-level ARM_CCI_PMU option.

Signed-off-by Robin Murphy <[email protected]>

---

v2: Move ARM/64 dependency up accordingly

 drivers/perf/Kconfig   | 34 ++++++++++++++++++----------------
 drivers/perf/arm-cci.c | 17 ++++++++++++++++-
 2 files changed, 34 insertions(+), 17 deletions(-)

drivers/perf/Kconfig +18 ~~-16~~

index 28bb5a029558..110330ecf714 100644
@@ -6,30 +6,32 @@ menu "Performance monitor support"
 	depends on PERF_EVENTS
 
 config ARM_CCI_PMU
-	bool
+	tristate "ARM CCI PMU driver"
+	depends on (ARM && CPU_V7) || ARM64
 	select ARM_CCI
+	help
+	  Support for PMU events monitoring on the ARM CCI (Cache Coherent
+	  Interconnect) family of products.
+
+	  If compiled as a module, it will be called arm-cci.
 
 config ARM_CCI400_PMU
-	bool "ARM CCI400 PMU support"
-	depends on (ARM && CPU_V7) || ARM64
+	bool "support CCI-400"
+	default y
+	depends on ARM_CCI_PMU
 	select ARM_CCI400_COMMON
-	select ARM_CCI_PMU
 	help
-	  Support for PMU events monitoring on the ARM CCI-400 (cache coherent
-	  interconnect). CCI-400 supports counting events related to the
-	  connected slave/master interfaces.
+	  CCI-400 provides 4 independent event counters counting events related
+	  to the connected slave/master interfaces, plus a cycle counter.
 
 config ARM_CCI5xx_PMU
-	bool "ARM CCI-500/CCI-550 PMU support"
-	depends on (ARM && CPU_V7) || ARM64
-	select ARM_CCI_PMU
+	bool "support CCI-500/CCI-550"
+	default y
+	depends on ARM_CCI_PMU
 	help
-	  Support for PMU events monitoring on the ARM CCI-500/CCI-550 cache
-	  coherent interconnects. Both of them provide 8 independent event counters,
-	  which can count events pertaining to the slave/master interfaces as well
-	  as the internal events to the CCI.
-
-	  If unsure, say Y
+	  CCI-500/CCI-550 both provide 8 independent event counters, which can
+	  count events pertaining to the slave/master interfaces as well as the
+	  internal events to the CCI.
 
 config ARM_CCN
 	tristate "ARM CCN driver support"

drivers/perf/arm-cci.c +16 -1

index 7029d8fe8f44..09938dd8eb6f 100644
@@ -1416,6 +1416,7 @@ static int cci_pmu_init(struct cci_pmu *cci_pmu, struct platform_device *pdev)
 	pmu_format_attr_group.attrs = model->format_attrs;
 
 	cci_pmu->pmu = (struct pmu) {
+		.module		= THIS_MODULE,
 		.name		= cci_pmu->model->name,
 		.task_ctx_nr	= perf_invalid_context,
 		.pmu_enable	= cci_pmu_enable,

@@ -1581,6 +1582,7 @@ static const struct of_device_id arm_cci_pmu_matches[] = {
 #endif
 	{},
 };
+MODULE_DEVICE_TABLE(of, arm_cci_pmu_matches);
 
 static bool is_duplicate_irq(int irq, int *irqs, int nr_irqs)
 {

@@ -1702,14 +1704,27 @@ static int cci_pmu_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int cci_pmu_remove(struct platform_device *pdev)
+{
+	if (!g_cci_pmu)
+		return 0;
+
+	cpuhp_remove_state(CPUHP_AP_PERF_ARM_CCI_ONLINE);
+	perf_pmu_unregister(&g_cci_pmu->pmu);
+	g_cci_pmu = NULL;
+
+	return 0;
+}
+
 static struct platform_driver cci_pmu_driver = {
 	.driver = {
 		   .name = DRIVER_NAME,
 		   .of_match_table = arm_cci_pmu_matches,
 		  },
 	.probe = cci_pmu_probe,
+	.remove = cci_pmu_remove,
 };
 
-builtin_platform_driver(cci_pmu_driver);
+module_platform_driver(cci_pmu_driver);
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("ARM CCI PMU support");

Signature · 1 line

2.17.0.dirty