[Intel-gfx] [PATCH] drm/i915: be more solid in checking the alignment

[Matthew Auld]

The alignment is u64, and yet is_power_of_2() assumes unsigned long,
which might give different results between 32b and 64b kernel.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 3 ++-
 drivers/gpu/drm/i915/i915_utils.h              | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 7bb27f382af7..b62576f34a1d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -430,7 +430,8 @@ eb_validate_vma(struct i915_execbuffer *eb,
 	if (unlikely(entry->flags & eb->invalid_flags))
 		return -EINVAL;
 
-	if (unlikely(entry->alignment && !is_power_of_2(entry->alignment)))
+	if (unlikely(entry->alignment &&
+		     !is_power_of_2_u64(entry->alignment)))
 		return -EINVAL;
 
 	/*
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index cae0ae520398..024a9e224ff3 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -236,6 +236,11 @@ static inline u64 ptr_to_u64(const void *ptr)
 	__idx;								\
 })
 
+static inline bool is_power_of_2_u64(u64 n)
+{
+	return (n != 0 && ((n & (n - 1)) == 0));
+}
+
 static inline void __list_del_many(struct list_head *head,
 				   struct list_head *first)
 {
-- 
2.20.1