Add support to permit mapping memory with protection infoHEADmaster

The standard galcore user memory mapping function fails when asked to
map read-only memory, such as X shmem buffers.  The reason these fail
is because get_user_pages() is always attempted with "write" mode
enabled, which is not permissible with read-only mappings.

To allow this to work (so that Xv can be implemented efficiently) we
must be able to map read-only buffers.  This adds an extension to
etnaviv, found in my Dove galcore driver and Jon Nettleton's iMX6
kernels which permit this without changing the existing galcore APIs.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>

4 files changed, 55 insertions, 0 deletions

diff --git a/src/etnaviv/etna_bo.c b/src/etnaviv/etna_bo.c
index ea5248b..010b62a 100644
--- a/src/etnaviv/etna_bo.c
+++ b/src/etnaviv/etna_bo.c
@@ -232,6 +232,24 @@ struct etna_bo* etna_bo_new(struct viv_conn *conn, size_t bytes, uint32_t flags)
     return mem;
 }
 
+struct etna_bo *etna_bo_from_usermem_prot(struct viv_conn *conn, void *memory, size_t size, int prot)
+{
+    struct etna_bo *mem = ETNA_CALLOC_STRUCT(etna_bo);
+    if(mem == NULL) return NULL;
+
+    mem->bo_type = ETNA_BO_TYPE_USERMEM;
+    mem->logical = memory;
+    mem->size = size;
+
+    if(viv_map_user_memory_prot(conn, memory, size, prot, &mem->usermem_info, &mem->address)!=0)
+    {
+        ETNA_FREE(mem);
+        return NULL;
+    }
+
+    return mem;
+}
+
 struct etna_bo *etna_bo_from_usermem(struct viv_conn *conn, void *memory, size_t size)
 {
     struct etna_bo *mem = ETNA_CALLOC_STRUCT(etna_bo);
diff --git a/src/etnaviv/etna_bo.h b/src/etnaviv/etna_bo.h
index a4f1024..ad5bffb 100644
--- a/src/etnaviv/etna_bo.h
+++ b/src/etnaviv/etna_bo.h
@@ -62,6 +62,9 @@ struct etna_bo;
 /* Allocate linear block of video memory */
 struct etna_bo *etna_bo_new(struct viv_conn *conn, size_t bytes, uint32_t flags);
 
+/* Map user memory (which may be write protected) into GPU memory space */
+struct etna_bo *etna_bo_from_usermem_prot(struct viv_conn *conn, void *memory, size_t size, int prot);
+
 /* Map user memory into GPU memory space */
 struct etna_bo *etna_bo_from_usermem(struct viv_conn *conn, void *memory, size_t size);
 
diff --git a/src/etnaviv/viv.c b/src/etnaviv/viv.c
index b3f6225..f476a47 100644
--- a/src/etnaviv/viv.c
+++ b/src/etnaviv/viv.c
@@ -70,6 +70,17 @@ struct viv_dmabuf_map {
 };
 #define IOC_GDMABUF_MAP _IOWR('_', 0, struct viv_dmabuf_map)
 
+/* rmk's extension for mapping read-only memory (X shmem buffers) */
+struct viv_membuf_map {
+    union rmk_gcabi_header hdr;
+    uint64_t info;
+    uint64_t address;
+    uint64_t virt;
+    uint32_t size;
+    uint32_t prot;
+};
+#define IOC_GMEMBUF_MAP _IOWR('_', 1, struct viv_membuf_map)
+
 const char *galcore_device[] = {"/dev/gal3d", "/dev/galcore", "/dev/graphics/galcore", NULL};
 #define INTERFACE_SIZE (sizeof(gcsHAL_INTERFACE))
 
@@ -616,6 +627,24 @@ int viv_map_dmabuf(struct viv_conn *conn, int fd, viv_usermem_t *info, viv_addr_
     return VIV_STATUS_OK;
 }
 
+int viv_map_user_memory_prot(struct viv_conn *conn, void *memory, size_t size, int prot, viv_usermem_t *info, viv_addr_t *address)
+{
+    struct viv_membuf_map map = {
+#ifdef GCABI_HAS_HARDWARE_TYPE
+        .hdr.v4.hwtype = (gceHARDWARE_TYPE)conn->hw_type,
+#endif
+        .virt = (uintptr_t)memory,
+        .size = size,
+        .prot = prot,
+    };
+    int ret = viv_ioctl(conn, IOC_GMEMBUF_MAP, &map, sizeof(map));
+    if(ret < 0 || map.hdr.v4.status)
+        return -1;
+    *info = VIV_TO_HANDLE(map.info);
+    *address = map.address;
+    return VIV_STATUS_OK;
+}
+
 int viv_map_user_memory(struct viv_conn *conn, void *memory, size_t size, viv_usermem_t *info, viv_addr_t *address)
 {
     gcsHAL_INTERFACE id = {
diff --git a/src/etnaviv/viv.h b/src/etnaviv/viv.h
index ec044f5..4496840 100644
--- a/src/etnaviv/viv.h
+++ b/src/etnaviv/viv.h
@@ -268,6 +268,11 @@ int viv_free_contiguous(struct viv_conn *conn, size_t bytes, viv_addr_t physical
  */
 int viv_map_dmabuf(struct viv_conn *conn, int fd, viv_usermem_t *info, viv_addr_t *address, int prot);
 
+/** Map user memory to GPU memory, allowing for read/write protections.
+ * Note: GPU is not protected against reads/writes.
+ */
+int viv_map_user_memory_prot(struct viv_conn *conn, void *memory, size_t size, int prot, viv_usermem_t *info, viv_addr_t *address);
+
 /** Map user memory to GPU memory.
  */
 int viv_map_user_memory(struct viv_conn *conn, void *memory, size_t size, viv_usermem_t *info, viv_addr_t *address);