As these functions are only used by one driver and there are security holes
in these functions. Make the functions optional.

These changes are based on the two patches:
  commit c21eb21cb50d58e7cbdcb8b9e7ff68b85cfa5095
  Author: Dave Airlie <airlied at redhat.com>

And the commit that the above patch reverts:
  commit 7c510133d93dd6f15ca040733ba7b2891ed61fd1
  Author: Daniel Vetter <daniel.vetter at ffwll.ch>

This should now turn off the context feature.

Issue: VIZ-5485
Signed-off-by: Peter Antoine <peter.antoine at intel.com>
---
 drivers/gpu/drm/drm_context.c | 36 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_drv.c     | 12 +++++++-----
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_context.c b/drivers/gpu/drm/drm_context.c
index 1febcd3..09af26c 100644
--- a/drivers/gpu/drm/drm_context.c
+++ b/drivers/gpu/drm/drm_context.c
@@ -53,6 +53,9 @@ struct drm_ctx_list {
  */
 void drm_legacy_ctxbitmap_free(struct drm_device * dev, int ctx_handle)
 {
+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        mutex_lock(&dev->struct_mutex);
        idr_remove(&dev->ctx_idr, ctx_handle);
        mutex_unlock(&dev->struct_mutex);
@@ -87,6 +90,9 @@ static int drm_legacy_ctxbitmap_next(struct drm_device * dev)
  */
 int drm_legacy_ctxbitmap_init(struct drm_device * dev)
 {
+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        idr_init(&dev->ctx_idr);
        return 0;
 }
@@ -101,6 +107,9 @@ int drm_legacy_ctxbitmap_init(struct drm_device * dev)
  */
 void drm_legacy_ctxbitmap_cleanup(struct drm_device * dev)
 {
+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        mutex_lock(&dev->struct_mutex);
        idr_destroy(&dev->ctx_idr);
        mutex_unlock(&dev->struct_mutex);
@@ -119,6 +128,9 @@ void drm_legacy_ctxbitmap_flush(struct drm_device *dev, 
struct drm_file *file)
 {
        struct drm_ctx_list *pos, *tmp;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        mutex_lock(&dev->ctxlist_mutex);

        list_for_each_entry_safe(pos, tmp, &dev->ctxlist, head) {
@@ -161,6 +173,9 @@ int drm_legacy_getsareactx(struct drm_device *dev, void 
*data,
        struct drm_local_map *map;
        struct drm_map_list *_entry;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        mutex_lock(&dev->struct_mutex);

        map = idr_find(&dev->ctx_idr, request->ctx_id);
@@ -205,6 +220,9 @@ int drm_legacy_setsareactx(struct drm_device *dev, void 
*data,
        struct drm_local_map *map = NULL;
        struct drm_map_list *r_list = NULL;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        mutex_lock(&dev->struct_mutex);
        list_for_each_entry(r_list, &dev->maplist, head) {
                if (r_list->map
@@ -311,6 +329,9 @@ int drm_legacy_resctx(struct drm_device *dev, void *data,
        struct drm_ctx ctx;
        int i;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        if (res->count >= DRM_RESERVED_CONTEXTS) {
                memset(&ctx, 0, sizeof(ctx));
                for (i = 0; i < DRM_RESERVED_CONTEXTS; i++) {
@@ -341,6 +362,9 @@ int drm_legacy_addctx(struct drm_device *dev, void *data,
        struct drm_ctx_list *ctx_entry;
        struct drm_ctx *ctx = data;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        ctx->handle = drm_legacy_ctxbitmap_next(dev);
        if (_DRM_LOCKING_CONTEXT(ctx->handle) == DRM_KERNEL_CONTEXT) {
                /* Skip kernel's context and get a new one. */
@@ -384,6 +408,9 @@ int drm_legacy_getctx(struct drm_device *dev, void *data,
 {
        struct drm_ctx *ctx = data;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        /* This is 0, because we don't handle any context flags */
        ctx->flags = 0;

@@ -406,6 +433,9 @@ int drm_legacy_switchctx(struct drm_device *dev, void *data,
 {
        struct drm_ctx *ctx = data;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        DRM_DEBUG("%d\n", ctx->handle);
        return drm_context_switch(dev, dev->last_context, ctx->handle);
 }
@@ -426,6 +456,9 @@ int drm_legacy_newctx(struct drm_device *dev, void *data,
 {
        struct drm_ctx *ctx = data;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        DRM_DEBUG("%d\n", ctx->handle);
        drm_context_switch_complete(dev, file_priv, ctx->handle);

@@ -448,6 +481,9 @@ int drm_legacy_rmctx(struct drm_device *dev, void *data,
 {
        struct drm_ctx *ctx = data;

+       if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               return -EINVAL;
+
        DRM_DEBUG("%d\n", ctx->handle);
        if (_DRM_LOCKING_CONTEXT(ctx->handle) != DRM_KERNEL_CONTEXT) {
                if (dev->driver->context_dtor)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 48f7359..dc662e8 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -596,11 +596,13 @@ struct drm_device *drm_dev_alloc(struct drm_driver 
*driver,
        if (drm_ht_create(&dev->map_hash, 12))
                goto err_minors;

-       ret = drm_legacy_ctxbitmap_init(dev);
-       if (ret) {
-               DRM_ERROR("Cannot allocate memory for context bitmap.\n");
-               goto err_ht;
-       }
+       if (drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT))
+               ret = drm_legacy_ctxbitmap_init(dev);
+               if (ret) {
+                       DRM_ERROR(
+                               "Cannot allocate memory for context bitmap.\n");
+                       goto err_ht;
+               }

        if (drm_core_check_feature(dev, DRIVER_GEM)) {
                ret = drm_gem_init(dev);
-- 
1.9.1

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