kernel/linux.git/drivers/gpu, branch v5.7.3

drm/vkms: Hold gem object while still in-use

2020-06-17T14:43:02+00:00

commit 0ea2ea42b31abc1141f2fd3911f952a97d401fcb upstream. We need to keep the reference to the drm_gem_object until the last access by vkms_dumb_create. Therefore, the put the object after it is used. This fixes a use-after-free issue reported by syzbot. While here, change vkms_gem_create() symbol to static. Reported-and-tested-by: syzbot+e3372a2afe1e7ef04bc7@syzkaller.appspotmail.com Signed-off-by: Ezequiel Garcia Reviewed-by: Rodrigo Siqueira Signed-off-by: Rodrigo Siqueira Link: https://patchwork.freedesktop.org/patch/msgid/20200427214405.13069-1-ezequiel@collabora.com Signed-off-by: Greg Kroah-Hartman

gup: document and work around "COW can break either way" issue

2020-06-17T14:42:55+00:00

commit 17839856fd588f4ab6b789f482ed3ffd7c403e1f upstream. Doing a "get_user_pages()" on a copy-on-write page for reading can be ambiguous: the page can be COW'ed at any time afterwards, and the direction of a COW event isn't defined. Yes, whoever writes to it will generally do the COW, but if the thread that did the get_user_pages() unmapped the page before the write (and that could happen due to memory pressure in addition to any outright action), the writer could also just take over the old page instead. End result: the get_user_pages() call might result in a page pointer that is no longer associated with the original VM, and is associated with - and controlled by - another VM having taken it over instead. So when doing a get_user_pages() on a COW mapping, the only really safe thing to do would be to break the COW when getting the page, even when only getting it for reading. At the same time, some users simply don't even care. For example, the perf code wants to look up the page not because it cares about the page, but because the code simply wants to look up the physical address of the access for informational purposes, and doesn't really care about races when a page might be unmapped and remapped elsewhere. This adds logic to force a COW event by setting FOLL_WRITE on any copy-on-write mapping when FOLL_GET (or FOLL_PIN) is used to get a page pointer as a result. The current semantics end up being: - __get_user_pages_fast(): no change. If you don't ask for a write, you won't break COW. You'd better know what you're doing. - get_user_pages_fast(): the fast-case "look it up in the page tables without anything getting mmap_sem" now refuses to follow a read-only page, since it might need COW breaking. Which happens in the slow path - the fast path doesn't know if the memory might be COW or not. - get_user_pages() (including the slow-path fallback for gup_fast()): for a COW mapping, turn on FOLL_WRITE for FOLL_GET/FOLL_PIN, with very similar semantics to FOLL_FORCE. If it turns out that we want finer granularity (ie "only break COW when it might actually matter" - things like the zero page are special and don't need to be broken) we might need to push these semantics deeper into the lookup fault path. So if people care enough, it's possible that we might end up adding a new internal FOLL_BREAK_COW flag to go with the internal FOLL_COW flag we already have for tracking "I had a COW". Alternatively, if it turns out that different callers might want to explicitly control the forced COW break behavior, we might even want to make such a flag visible to the users of get_user_pages() instead of using the above default semantics. But for now, this is mostly commentary on the issue (this commit message being a lot bigger than the patch, and that patch in turn is almost all comments), with that minimal "enable COW breaking early" logic using the existing FOLL_WRITE behavior. [ It might be worth noting that we've always had this ambiguity, and it could arguably be seen as a user-space issue. You only get private COW mappings that could break either way in situations where user space is doing cooperative things (ie fork() before an execve() etc), but it _is_ surprising and very subtle, and fork() is supposed to give you independent address spaces. So let's treat this as a kernel issue and make the semantics of get_user_pages() easier to understand. Note that obviously a true shared mapping will still get a page that can change under us, so this does _not_ mean that get_user_pages() somehow returns any "stable" page ] Reported-by: Jann Horn Tested-by: Christoph Hellwig Acked-by: Oleg Nesterov Acked-by: Kirill Shutemov Acked-by: Jan Kara Cc: Andrea Arcangeli Cc: Matthew Wilcox Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Merge tag 'drm-fixes-2020-05-29-1' of git://anongit.freedesktop.org/drm/drm

2020-05-29T19:32:46+00:00

Pull drm fixes from Dave Airlie: "A couple of amdgpu fixes and minor ingenic fixes: amdgpu: - display atomic test fix - Fix soft hang in display vupdate code ingenic: - fix pointer cast - fix crtc atomic check callback" * tag 'drm-fixes-2020-05-29-1' of git://anongit.freedesktop.org/drm/drm: drm/amd/display: Fix potential integer wraparound resulting in a hang drm/amd/display: drop cursor position check in atomic test gpu/drm: Ingenic: Fix opaque pointer casted to wrong type gpu/drm: ingenic: Fix bogus crtc_atomic_check callback

Merge tag 'drm-misc-fixes-2020-05-28' of git://anongit.freedesktop.org/drm/drm-misc into drm-fixes

2020-05-29T02:11:11+00:00

Two ingenic fixes, one for a wrong cast, the other for a typo in a comparison Signed-off-by: Dave Airlie From: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20200528110944.hanv4qgc6w7whnj3@gilmour.lan

drm/amd/display: Fix potential integer wraparound resulting in a hang

2020-05-27T22:13:14+00:00

[Why] If VUPDATE_END is before VUPDATE_START the delay calculated can become very large, causing a soft hang. [How] Take the absolute value of the difference between START and END. Signed-off-by: Aric Cyr Reviewed-by: Nicholas Kazlauskas Acked-by: Qingqing Zhuo Signed-off-by: Alex Deucher Cc: stable@vger.kernel.org

drm/amd/display: drop cursor position check in atomic test

2020-05-27T22:12:32+00:00

get_cursor_position already handles the case where the cursor has negative off-screen coordinates by not setting dc_cursor_position.enabled. Signed-off-by: Simon Ser Fixes: 626bf90fe03f ("drm/amd/display: add basic atomic check for cursor plane") Cc: Alex Deucher Cc: Nicholas Kazlauskas Signed-off-by: Alex Deucher Cc: stable@vger.kernel.org

Merge branch 'for-5.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2020-05-27T17:58:19+00:00

Pull cgroup fixes from Tejun Heo: - Reverted stricter synchronization for cgroup recursive stats which was prepping it for event counter usage which never got merged. The change was causing performation regressions in some cases. - Restore bpf-based device-cgroup operation even when cgroup1 device cgroup is disabled. - An out-param init fix. * 'for-5.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: device_cgroup: Cleanup cgroup eBPF device filter code xattr: fix uninitialized out-param Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window"

Merge tag 'amd-drm-fixes-5.7-2020-05-21' of git://people.freedesktop.org/~agd5f/linux into drm-fixes

2020-05-22T00:30:51+00:00

amd-drm-fixes-5.7-2020-05-21: amdgpu: - DP fix - Floating point fix - Fix cursor stutter issue Signed-off-by: Dave Airlie From: Alex Deucher Link: https://patchwork.freedesktop.org/patch/msgid/20200521222415.4122-1-alexander.deucher@amd.com

Merge branch 'etnaviv/fixes' of https://git.pengutronix.de/git/lst/linux into drm-fixes

2020-05-22T00:25:11+00:00

two fixes: - memory leak fix when userspace passes a invalid softpin address - off-by-one crashing the kernel in the perfmon domain iteration when the GPU core has both 2D and 3D capabilities Signed-off-by: Dave Airlie From: Lucas Stach Link: https://patchwork.freedesktop.org/patch/msgid/ca7bce5c8aff0fcbbdc3bf2b9723df5f687c8924.camel@pengutronix.de

drm/amd/display: Defer cursor lock until after VUPDATE

2020-05-20T21:32:13+00:00

[Why] We dropped the delay after changed the cursor functions locking the entire pipe to locking just the CURSOR registers to fix page flip stuttering - this introduced cursor stuttering instead, and an underflow issue. The cursor update can be delayed indefinitely if the cursor update repeatedly happens right around VUPDATE. The underflow issue can happen if we do a viewport update on a pipe on the same frame where a cursor update happens around VUPDATE - the old cursor registers are retained which can be in an invalid position. This can cause a pipe hang and indefinite underflow. [How] The complex, ideal solution to the problem would be a software triple buffering mechanism from the DM layer to program only one cursor update per frame just before VUPDATE. The simple workaround until we have that infrastructure in place is this change - bring back the delay until VUPDATE before locking, but with some corrections to the calculations. This didn't work for all timings before because the calculation for VUPDATE was wrong - it was using the offset from VSTARTUP instead and didn't correctly handle the case where VUPDATE could be in the back porch. Add a new hardware sequencer function to use the existing helper to calculate the real VUPDATE start and VUPDATE end - VUPDATE can last multiple lines after all. Change the udelay to incorporate the width of VUPDATE as well. Signed-off-by: Nicholas Kazlauskas Reviewed-by: Aric Cyr Acked-by: Rodrigo Siqueira Signed-off-by: Alex Deucher