From: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
Enforce that an mmap of a dmabuf is always using MAP_SHARED so that all
access (both read and writes) using the device memory and not a local
copy-on-write page in system memory.
Signed-off-by: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
---
drivers/dma-buf/dma-buf.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 21916bba77d5..1ec297241842 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -25,6 +25,7 @@
#include <linux/poll.h>
#include <linux/dma-resv.h>
#include <linux/mm.h>
+#include <linux/mman.h>
#include <linux/mount.h>
#include <linux/pseudo_fs.h>
@@ -128,6 +129,19 @@ static struct file_system_type dma_buf_fs_type = {
.kill_sb = kill_anon_super,
};
+static unsigned long
+dma_buf_get_unmapped_area(struct file *file,
+ unsigned long addr,
+ unsigned long len,
+ unsigned long pgoff,
+ unsigned long flags)
+{
+ if ((flags & MAP_TYPE) == MAP_PRIVATE)
+ return -EINVAL;
+
+ return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
+}
+
static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
{
struct dma_buf *dmabuf;
@@ -508,6 +522,7 @@ static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
static const struct file_operations dma_buf_fops = {
.release = dma_buf_file_release,
+ .get_unmapped_area = dma_buf_get_unmapped_area,
.mmap = dma_buf_mmap_internal,
.llseek = dma_buf_llseek,
.poll = dma_buf_poll,
--
2.40.1
