treewide: Make all debug_obj_descriptors const

This should make it harder for the kernel to corrupt the debug object
descriptor, used to call functions to fixup state and track debug objects,
by moving the structure to read-only memory.
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200815004027.2046113-3-swboyd@chromium.org

drivers/gpu/drm/i915/i915_active.c

@@ -81,7 +81,7 @@ static void *active_debug_hint(void *addr)
 	return (void *)ref->active ?: (void *)ref->retire ?: (void *)ref;
 }
 
-static struct debug_obj_descr active_debug_desc = {
+static const struct debug_obj_descr active_debug_desc = {
 	.name = "i915_active",
 	.debug_hint = active_debug_hint,
 };

drivers/gpu/drm/i915/i915_sw_fence.c

@@ -34,7 +34,7 @@ static void *i915_sw_fence_debug_hint(void *addr)
 
 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
 
-static struct debug_obj_descr i915_sw_fence_debug_descr = {
+static const struct debug_obj_descr i915_sw_fence_debug_descr = {
 	.name = "i915_sw_fence",
 	.debug_hint = i915_sw_fence_debug_hint,
 };

kernel/rcu/rcu.h

@@ -167,7 +167,7 @@ static inline unsigned long rcu_seq_diff(unsigned long new, unsigned long old)
 # define STATE_RCU_HEAD_READY	0
 # define STATE_RCU_HEAD_QUEUED	1
 
-extern struct debug_obj_descr rcuhead_debug_descr;
+extern const struct debug_obj_descr rcuhead_debug_descr;
 
 static inline int debug_rcu_head_queue(struct rcu_head *head)
 {

kernel/rcu/update.c

@@ -469,7 +469,7 @@ void destroy_rcu_head_on_stack(struct rcu_head *head)
 }
 EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
 
-struct debug_obj_descr rcuhead_debug_descr = {
+const struct debug_obj_descr rcuhead_debug_descr = {
 	.name = "rcu_head",
 	.is_static_object = rcuhead_is_static_object,
 };

kernel/time/hrtimer.c

@@ -342,7 +342,7 @@ EXPORT_SYMBOL_GPL(ktime_add_safe);
 
 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 
-static struct debug_obj_descr hrtimer_debug_descr;
+static const struct debug_obj_descr hrtimer_debug_descr;
 
 static void *hrtimer_debug_hint(void *addr)
 {
@@ -401,7 +401,7 @@ static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 	}
 }
 
-static struct debug_obj_descr hrtimer_debug_descr = {
+static const struct debug_obj_descr hrtimer_debug_descr = {
 	.name		= "hrtimer",
 	.debug_hint	= hrtimer_debug_hint,
 	.fixup_init	= hrtimer_fixup_init,

kernel/time/timer.c

@@ -611,7 +611,7 @@ static void internal_add_timer(struct timer_base *base, struct timer_list *timer
 
 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 
-static struct debug_obj_descr timer_debug_descr;
+static const struct debug_obj_descr timer_debug_descr;
 
 static void *timer_debug_hint(void *addr)
 {
@@ -707,7 +707,7 @@ static bool timer_fixup_assert_init(void *addr, enum debug_obj_state state)
 	}
 }
 
-static struct debug_obj_descr timer_debug_descr = {
+static const struct debug_obj_descr timer_debug_descr = {
 	.name			= "timer_list",
 	.debug_hint		= timer_debug_hint,
 	.is_static_object	= timer_is_static_object,

kernel/workqueue.c

@@ -427,7 +427,7 @@ static void show_pwq(struct pool_workqueue *pwq);
 
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 
-static struct debug_obj_descr work_debug_descr;
+static const struct debug_obj_descr work_debug_descr;
 
 static void *work_debug_hint(void *addr)
 {
@@ -477,7 +477,7 @@ static bool work_fixup_free(void *addr, enum debug_obj_state state)
 	}
 }
 
-static struct debug_obj_descr work_debug_descr = {
+static const struct debug_obj_descr work_debug_descr = {
 	.name		= "work_struct",
 	.debug_hint	= work_debug_hint,
 	.is_static_object = work_is_static_object,

lib/percpu_counter.c

@@ -17,7 +17,7 @@ static DEFINE_SPINLOCK(percpu_counters_lock);
 
 #ifdef CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER
 
-static struct debug_obj_descr percpu_counter_debug_descr;
+static const struct debug_obj_descr percpu_counter_debug_descr;
 
 static bool percpu_counter_fixup_free(void *addr, enum debug_obj_state state)
 {
@@ -33,7 +33,7 @@ static bool percpu_counter_fixup_free(void *addr, enum debug_obj_state state)
 	}
 }
 
-static struct debug_obj_descr percpu_counter_debug_descr = {
+static const struct debug_obj_descr percpu_counter_debug_descr = {
 	.name		= "percpu_counter",
 	.fixup_free	= percpu_counter_fixup_free,
 };