[PATCH] drm/i915: check to see if the FPU is available before using it

[Jason A. Donenfeld]

It's not safe to just grab the FPU willy nilly without first checking to
see if it's available. This patch adds the usual call to may_use_simd()
and falls back to boring memcpy if it's not available.

Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_memcpy.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_memcpy.c b/drivers/gpu/drm/i915/i915_memcpy.c
index fdd550405fd3..7c0e022586bc 100644
--- a/drivers/gpu/drm/i915/i915_memcpy.c
+++ b/drivers/gpu/drm/i915/i915_memcpy.c
@@ -24,6 +24,7 @@
 
 #include <linux/kernel.h>
 #include <asm/fpu/api.h>
+#include <asm/simd.h>
 
 #include "i915_memcpy.h"
 
@@ -38,6 +39,12 @@ static DEFINE_STATIC_KEY_FALSE(has_movntdqa);
 #ifdef CONFIG_AS_MOVNTDQA
 static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
 {
+	if (unlikely(!may_use_simd())) {
+		memcpy(dst, src, len);
+		return;
+	}
+
+
 	kernel_fpu_begin();
 
 	while (len >= 4) {
@@ -67,6 +74,11 @@ static void __memcpy_ntdqa(void *dst, const void *src, unsigned long len)
 
 static void __memcpy_ntdqu(void *dst, const void *src, unsigned long len)
 {
+	if (unlikely(!may_use_simd())) {
+		memcpy(dst, src, len);
+		return;
+	}
+
 	kernel_fpu_begin();
 
 	while (len >= 4) {
-- 
2.26.0