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

Cc: Neil Armstrong <narmstrong@baylibre.com>
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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
This commit is contained in:
Dave Airlie 2018-10-04 10:37:30 +10:00
parent d04a836ea7 4be9bd10e2
commit 29b90203f8
2 changed files with 51 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/gpu/drm/Kconfig
View File

@ -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

33
drivers/gpu/drm/drm_fb_helper.c
View File

@ -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);