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-rw-r--r--drivers/gpu/drm/drm_bufs.c35
1 files changed, 31 insertions, 4 deletions
diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c
index cddea1a2472..6d80d17f1e9 100644
--- a/drivers/gpu/drm/drm_bufs.c
+++ b/drivers/gpu/drm/drm_bufs.c
@@ -34,6 +34,8 @@
*/
#include <linux/vmalloc.h>
+#include <linux/log2.h>
+#include <asm/shmparam.h>
#include "drmP.h"
resource_size_t drm_get_resource_start(struct drm_device *dev, unsigned int resource)
@@ -83,9 +85,11 @@ static struct drm_map_list *drm_find_matching_map(struct drm_device *dev,
}
static int drm_map_handle(struct drm_device *dev, struct drm_hash_item *hash,
- unsigned long user_token, int hashed_handle)
+ unsigned long user_token, int hashed_handle, int shm)
{
- int use_hashed_handle;
+ int use_hashed_handle, shift;
+ unsigned long add;
+
#if (BITS_PER_LONG == 64)
use_hashed_handle = ((user_token & 0xFFFFFFFF00000000UL) || hashed_handle);
#elif (BITS_PER_LONG == 32)
@@ -101,9 +105,31 @@ static int drm_map_handle(struct drm_device *dev, struct drm_hash_item *hash,
if (ret != -EINVAL)
return ret;
}
+
+ shift = 0;
+ add = DRM_MAP_HASH_OFFSET >> PAGE_SHIFT;
+ if (shm && (SHMLBA > PAGE_SIZE)) {
+ int bits = ilog2(SHMLBA >> PAGE_SHIFT) + 1;
+
+ /* For shared memory, we have to preserve the SHMLBA
+ * bits of the eventual vma->vm_pgoff value during
+ * mmap(). Otherwise we run into cache aliasing problems
+ * on some platforms. On these platforms, the pgoff of
+ * a mmap() request is used to pick a suitable virtual
+ * address for the mmap() region such that it will not
+ * cause cache aliasing problems.
+ *
+ * Therefore, make sure the SHMLBA relevant bits of the
+ * hash value we use are equal to those in the original
+ * kernel virtual address.
+ */
+ shift = bits;
+ add |= ((user_token >> PAGE_SHIFT) & ((1UL << bits) - 1UL));
+ }
+
return drm_ht_just_insert_please(&dev->map_hash, hash,
user_token, 32 - PAGE_SHIFT - 3,
- 0, DRM_MAP_HASH_OFFSET >> PAGE_SHIFT);
+ shift, add);
}
/**
@@ -323,7 +349,8 @@ static int drm_addmap_core(struct drm_device * dev, resource_size_t offset,
/* We do it here so that dev->struct_mutex protects the increment */
user_token = (map->type == _DRM_SHM) ? (unsigned long)map->handle :
map->offset;
- ret = drm_map_handle(dev, &list->hash, user_token, 0);
+ ret = drm_map_handle(dev, &list->hash, user_token, 0,
+ (map->type == _DRM_SHM));
if (ret) {
if (map->type == _DRM_REGISTERS)
iounmap(map->handle);