From 04cfcc7ab358e331b32cabde1e853a125f3f8735 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 22 Aug 2018 10:54:02 +0200 Subject: fbdev: Drop FBINFO_CAN_FORCE_OUTPUT flag This was only added for the drm's fbdev emulation support, so that it would try harder to show the Oops. Unfortunately this never really worked reliably, and in practice ended up pushing the real Oops off the screen due to plentyfull locking, sleep-while-atomic and other issues. So we removed all that support from the fbdev emulation a while back. Aside: We've also removed the kgdb support, for similar reasons. Since it's such a small patch I figured I don't split this up into the usual 3-phase removal. Acked-by: Bartlomiej Zolnierkiewicz Cc: Ben Skeggs Cc: Bartlomiej Zolnierkiewicz Cc: Greg Kroah-Hartman Cc: Hans de Goede Cc: Daniel Vetter Cc: Alexander Kapshuk Cc: Kees Cook Cc: Thierry Reding Cc: David Lechner Cc: nouveau@lists.freedesktop.org Cc: linux-fbdev@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20180822085405.10787-1-daniel.vetter@ffwll.ch --- include/linux/fb.h | 4 ---- 1 file changed, 4 deletions(-) (limited to 'include/linux/fb.h') diff --git a/include/linux/fb.h b/include/linux/fb.h index 3cd375dafd0e..b1db5c5eb671 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -457,10 +457,6 @@ struct fb_tile_ops { */ #define FBINFO_BE_MATH 0x100000 -/* report to the VT layer that this fb driver can accept forced console - output like oopses */ -#define FBINFO_CAN_FORCE_OUTPUT 0x200000 - struct fb_info { atomic_t count; int node; -- cgit v1.2.3 From da6c7707caf3736c1cf968606bd97c07e79625d4 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 22 Aug 2018 10:54:04 +0200 Subject: fbdev: Add FBINFO_HIDE_SMEM_START flag DRM drivers really, really, really don't want random userspace to share buffer behind it's back, bypassing the dma-buf buffer sharing machanism. For that reason we've ruthlessly rejected any IOCTL exposing the physical address of any graphics buffer. Unfortunately fbdev comes with that built-in. We could just set smem_start to 0, but that means we'd have to hand-roll our own fb_mmap implementation. For good reasons many drivers do that, but smem_start/length is still super convenient. Hence instead just stop the leak in the ioctl, to keep fb mmap working as-is. A second patch will set this flag for all drm drivers. Acked-by: Bartlomiej Zolnierkiewicz Cc: Bartlomiej Zolnierkiewicz Cc: Kees Cook Cc: Daniel Vetter Cc: linux-fbdev@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20180822085405.10787-3-daniel.vetter@ffwll.ch --- drivers/video/fbdev/core/fbmem.c | 4 ++++ include/linux/fb.h | 7 +++++++ 2 files changed, 11 insertions(+) (limited to 'include/linux/fb.h') diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 0da75c55660d..861bf8081619 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1117,6 +1117,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, if (!lock_fb_info(info)) return -ENODEV; fix = info->fix; + if (info->flags & FBINFO_HIDE_SMEM_START) + fix.smem_start = 0; unlock_fb_info(info); ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0; @@ -1327,6 +1329,8 @@ static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd, if (!lock_fb_info(info)) return -ENODEV; fix = info->fix; + if (info->flags & FBINFO_HIDE_SMEM_START) + fix.smem_start = 0; unlock_fb_info(info); return do_fscreeninfo_to_user(&fix, compat_ptr(arg)); } diff --git a/include/linux/fb.h b/include/linux/fb.h index b1db5c5eb671..a3cab6dc9b44 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -456,6 +456,13 @@ struct fb_tile_ops { * and host endianness. Drivers should not use this flag. */ #define FBINFO_BE_MATH 0x100000 +/* + * Hide smem_start in the FBIOGET_FSCREENINFO IOCTL. This is used by modern DRM + * drivers to stop userspace from trying to share buffers behind the kernel's + * back. Instead dma-buf based buffer sharing should be used. + */ +#define FBINFO_HIDE_SMEM_START 0x200000 + struct fb_info { atomic_t count; -- cgit v1.2.3