Merge tag 'drm-misc-next-fixes-2018-10-03' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

- Add EXPERT config option to allow phys mem leak from fbdev for blob drivers (Neil)

Cc: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Sean Paul <sean@poorly.run>
Link: https://patchwork.freedesktop.org/patch/msgid/20181003195957.GA64584@art_vandelay

drivers/gpu/drm/Kconfig

@@ -110,6 +110,26 @@ config DRM_FBDEV_OVERALLOC
 	  is 100. Typical values for double buffering will be 200,
 	  triple buffering 300.
 
+config DRM_FBDEV_LEAK_PHYS_SMEM
+	bool "Shamelessly allow leaking of fbdev physical address (DANGEROUS)"
+	depends on DRM_FBDEV_EMULATION && EXPERT
+	default n
+	help
+	  In order to keep user-space compatibility, we want in certain
+	  use-cases to keep leaking the fbdev physical address to the
+	  user-space program handling the fbdev buffer.
+	  This affects, not only, Amlogic, Allwinner or Rockchip devices
+	  with ARM Mali GPUs using an userspace Blob.
+	  This option is not supported by upstream developers and should be
+	  removed as soon as possible and be considered as a broken and
+	  legacy behaviour from a modern fbdev device driver.
+
+	  Please send any bug reports when using this to your proprietary
+	  software vendor that requires this.
+
+	  If in doubt, say "N" or spread the word to your closed source
+	  library vendor.
+
 config DRM_LOAD_EDID_FIRMWARE
 	bool "Allow to specify an EDID data set instead of probing for it"
 	depends on DRM

drivers/gpu/drm/drm_fb_helper.c

@@ -56,6 +56,25 @@ MODULE_PARM_DESC(drm_fbdev_overalloc,
 		 "Overallocation of the fbdev buffer (%) [default="
 		 __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]");
 
+/*
+ * In order to keep user-space compatibility, we want in certain use-cases
+ * to keep leaking the fbdev physical address to the user-space program
+ * handling the fbdev buffer.
+ * This is a bad habit essentially kept into closed source opengl driver
+ * that should really be moved into open-source upstream projects instead
+ * of using legacy physical addresses in user space to communicate with
+ * other out-of-tree kernel modules.
+ *
+ * This module_param *should* be removed as soon as possible and be
+ * considered as a broken and legacy behaviour from a modern fbdev device.
+ */
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+static bool drm_leak_fbdev_smem = false;
+module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
+MODULE_PARM_DESC(fbdev_emulation,
+		 "Allow unsafe leaking fbdev physical smem address [default=false]");
+#endif
+
 static LIST_HEAD(kernel_fb_helper_list);
 static DEFINE_MUTEX(kernel_fb_helper_lock);
 
@@ -2670,8 +2689,12 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
 
 	info = fb_helper->fbdev;
 	info->var.pixclock = 0;
-	/* don't leak any physical addresses to userspace */
-	info->flags |= FBINFO_HIDE_SMEM_START;
+	/* Shamelessly allow physical address leaking to userspace */
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+	if (!drm_leak_fbdev_smem)
+#endif
+		/* don't leak any physical addresses to userspace */
+		info->flags |= FBINFO_HIDE_SMEM_START;
 
 	/* Need to drop locks to avoid recursive deadlock in
 	 * register_framebuffer. This is ok because the only thing left to do is
@@ -3081,6 +3104,12 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
 	fbi->screen_size = fb->height * fb->pitches[0];
 	fbi->fix.smem_len = fbi->screen_size;
 	fbi->screen_buffer = buffer->vaddr;
+	/* Shamelessly leak the physical address to user-space */
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+	if (drm_leak_fbdev_smem && fbi->fix.smem_start == 0)
+		fbi->fix.smem_start =
+			page_to_phys(virt_to_page(fbi->screen_buffer));
+#endif
 	strcpy(fbi->fix.id, "DRM emulated");
 
 	drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->format->depth);