From f3b896a8976058185b8512036328ce073f733b8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Winiarski?= <michal.winiarski@intel.com>
Date: Wed, 19 Feb 2020 17:18:22 +0100
Subject: drm/i915/pmu: Avoid using globals for PMU events
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Git-commit: 2de0147d77168d6a227c00eb9c5a49374e1582a3
Patch-mainline: v5.6-rc4
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Attempting to bind / unbind module from devices where we have both
integrated and discreete GPU handled by i915, will cause us to try and
double free the global state, hitting null ptr deref in free_event_attributes.

Let's move it to i915_pmu.

Fixes: 05488673a4d4 ("drm/i915/pmu: Support multiple GPUs")
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200219161822.24592-2-michal.winiarski@intel.com
(cherry picked from commit 46129dc10f47c5c2b51c93a82b7b2aca46574ae0)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/i915_pmu.c | 41 ++++++++++++++++++---------------
 drivers/gpu/drm/i915/i915_pmu.h |  4 ++++
 2 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 84301004d5c0..aa729d04abe2 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -822,11 +822,6 @@ static ssize_t i915_pmu_event_show(struct device *dev,
 	return sprintf(buf, "config=0x%lx\n", eattr->val);
 }
 
-static struct attribute_group i915_pmu_events_attr_group = {
-	.name = "events",
-	/* Patch in attrs at runtime. */
-};
-
 static ssize_t
 i915_pmu_get_attr_cpumask(struct device *dev,
 			  struct device_attribute *attr,
@@ -846,13 +841,6 @@ static const struct attribute_group i915_pmu_cpumask_attr_group = {
 	.attrs = i915_cpumask_attrs,
 };
 
-static const struct attribute_group *i915_pmu_attr_groups[] = {
-	&i915_pmu_format_attr_group,
-	&i915_pmu_events_attr_group,
-	&i915_pmu_cpumask_attr_group,
-	NULL
-};
-
 #define __event(__config, __name, __unit) \
 { \
 	.config = (__config), \
@@ -1026,16 +1014,16 @@ err:;
 
 static void free_event_attributes(struct i915_pmu *pmu)
 {
-	struct attribute **attr_iter = i915_pmu_events_attr_group.attrs;
+	struct attribute **attr_iter = pmu->events_attr_group.attrs;
 
 	for (; *attr_iter; attr_iter++)
 		kfree((*attr_iter)->name);
 
-	kfree(i915_pmu_events_attr_group.attrs);
+	kfree(pmu->events_attr_group.attrs);
 	kfree(pmu->i915_attr);
 	kfree(pmu->pmu_attr);
 
-	i915_pmu_events_attr_group.attrs = NULL;
+	pmu->events_attr_group.attrs = NULL;
 	pmu->i915_attr = NULL;
 	pmu->pmu_attr = NULL;
 }
@@ -1117,6 +1105,13 @@ static bool is_igp(struct drm_i915_private *i915)
 void i915_pmu_register(struct drm_i915_private *i915)
 {
 	struct i915_pmu *pmu = &i915->pmu;
+	const struct attribute_group *attr_groups[] = {
+		&i915_pmu_format_attr_group,
+		&pmu->events_attr_group,
+		&i915_pmu_cpumask_attr_group,
+		NULL
+	};
+
 	int ret = -ENOMEM;
 
 	if (INTEL_GEN(i915) <= 2) {
@@ -1143,11 +1138,16 @@ void i915_pmu_register(struct drm_i915_private *i915)
 	if (!pmu->name)
 		goto err;
 
-	i915_pmu_events_attr_group.attrs = create_event_attributes(pmu);
-	if (!i915_pmu_events_attr_group.attrs)
+	pmu->events_attr_group.name = "events";
+	pmu->events_attr_group.attrs = create_event_attributes(pmu);
+	if (!pmu->events_attr_group.attrs)
 		goto err_name;
 
-	pmu->base.attr_groups	= i915_pmu_attr_groups;
+	pmu->base.attr_groups = kmemdup(attr_groups, sizeof(attr_groups),
+					GFP_KERNEL);
+	if (!pmu->base.attr_groups)
+		goto err_attr;
+
 	pmu->base.task_ctx_nr	= perf_invalid_context;
 	pmu->base.event_init	= i915_pmu_event_init;
 	pmu->base.add		= i915_pmu_event_add;
@@ -1159,7 +1159,7 @@ void i915_pmu_register(struct drm_i915_private *i915)
 
 	ret = perf_pmu_register(&pmu->base, pmu->name, -1);
 	if (ret)
-		goto err_attr;
+		goto err_groups;
 
 	ret = i915_pmu_register_cpuhp_state(pmu);
 	if (ret)
@@ -1169,6 +1169,8 @@ void i915_pmu_register(struct drm_i915_private *i915)
 
 err_unreg:
 	perf_pmu_unregister(&pmu->base);
+err_groups:
+	kfree(pmu->base.attr_groups);
 err_attr:
 	pmu->base.event_init = NULL;
 	free_event_attributes(pmu);
@@ -1194,6 +1196,7 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
 
 	perf_pmu_unregister(&pmu->base);
 	pmu->base.event_init = NULL;
+	kfree(pmu->base.attr_groups);
 	if (!is_igp(i915))
 		kfree(pmu->name);
 	free_event_attributes(pmu);
diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h
index 207058391cec..f1d6cad0d7d5 100644
--- a/drivers/gpu/drm/i915/i915_pmu.h
+++ b/drivers/gpu/drm/i915/i915_pmu.h
@@ -107,6 +107,10 @@ struct i915_pmu {
 	 * @sleep_last: Last time GT parked for RC6 estimation.
 	 */
 	ktime_t sleep_last;
+	/**
+	 * @events_attr_group: Device events attribute group.
+	 */
+	struct attribute_group events_attr_group;
 	/**
 	 * @i915_attr: Memory block holding device attributes.
 	 */
-- 
2.28.0