[PATCH 5.5 087/151] drm/i915: be more solid in checking the alignment

[Greg Kroah-Hartman]

From: Matthew Auld <matthew.auld@xxxxxxxxx>

commit 1d61c5d711a2dc0b978ae905535edee9601f9449 upstream.

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@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20200305203534.210466-1-matthew.auld@xxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
(cherry picked from commit 2920516b2f719546f55079bc39a7fe409d9e80ab)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 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(-)

--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -441,7 +441,8 @@ eb_validate_vma(struct i915_execbuffer *
 	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;
 
 	/*
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -234,6 +234,11 @@ static inline u64 ptr_to_u64(const void
 	__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)
 {