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drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM

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Consolidate all handling of CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM by
making the module parameter optional in drm_fb_helper.c.

Without the config option, modules can set smem_start in struct
fb_info for internal usage, but not export if to userspace. The
address can only be exported by enabling the option and setting
the module parameter. Also update the comment.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Zack Rusin <zackr@vmware.com>
Tested-by: Sui Jingfeng<suijingfeng@loongson.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20230320150751.20399-8-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2023-03-20 16:07:50 +01:00
parent 61b5d0072a
commit a51c7663f1
3 changed files with 9 additions and 31 deletions
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22
drivers/gpu/drm/drm_fb_helper.c
View File

@ -60,16 +60,17 @@ MODULE_PARM_DESC(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 is a bad habit, essentially kept to support closed-source OpenGL
* drivers 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;
#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
MODULE_PARM_DESC(drm_leak_fbdev_smem,
"Allow unsafe leaking fbdev physical smem address [default=false]");
@ -1983,10 +1984,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
return ret;
}
#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
fb_helper->hint_leak_smem_start = drm_leak_fbdev_smem;
#endif
/* push down into drivers */
ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
if (ret < 0)
@ -2185,11 +2182,8 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper)
info = fb_helper->info;
info->var.pixclock = 0;
/* Shamelessly allow physical address leaking to userspace */
#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
if (!fb_helper->hint_leak_smem_start)
#endif
/* don't leak any physical addresses to userspace */
if (!drm_leak_fbdev_smem)
info->flags |= FBINFO_HIDE_SMEM_START;
/* Need to drop locks to avoid recursive deadlock in

9
drivers/gpu/drm/drm_fbdev_dma.c
View File

@ -136,16 +136,9 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper,
info->flags |= FBINFO_READS_FAST; /* signal caching */
info->screen_size = sizes->surface_height * fb->pitches[0];
info->screen_buffer = map.vaddr;
info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
info->fix.smem_len = info->screen_size;
#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
/*
* Shamelessly leak the physical address to user-space.
*/
if (fb_helper->hint_leak_smem_start && !info->fix.smem_start)
info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
#endif
return 0;
err_drm_client_buffer_vunmap:

9
include/drm/drm_fb_helper.h
View File

@ -195,15 +195,6 @@ struct drm_fb_helper {
*/
int preferred_bpp;
/**
* @hint_leak_smem_start:
*
* Hint to the fbdev emulation to store the framebuffer's physical
* address in struct &fb_info.fix.smem_start. If the hint is unset,
* the smem_start field should always be cleared to zero.
*/
bool hint_leak_smem_start;
#ifdef CONFIG_FB_DEFERRED_IO
/**
* @fbdefio: