- 27 Aug, 2013 2 commits
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David Herrmann authored
We implement automatic vma mmap() access management for all drivers using gem_mmap. We use the vma manager to add each open-file that creates a gem-handle to the vma-node of the underlying gem object. Once the handle is destroyed, we drop the open-file again. This allows us to use drm_vma_node_is_allowed() on _any_ gem object to see whether an open-file is granted access. In drm_gem_mmap() we use this to verify that unprivileged users cannot guess gem offsets and map arbitrary buffers. Note that this manages access for _all_ gem users (also TTM+GEM), but the actual access checks are only done for drm_gem_mmap(). TTM drivers use the TTM mmap helpers, which need to do that separately. Signed-off-by:
David Herrmann <dh.herrmann@gmail.com> Signed-off-by:
Dave Airlie <airlied@redhat.com>
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David Herrmann authored
The VMA offset manager uses a device-global address-space. Hence, any user can currently map any offset-node they want. They only need to guess the right offset. If we wanted per open-file offset spaces, we'd either need VM_NONLINEAR mappings or multiple "struct address_space" trees. As both doesn't really scale, we implement access management in the VMA manager itself. We use an rb-tree to store open-files for each VMA node. On each mmap call, GEM, TTM or the drivers must check whether the current user is allowed to map this file. We add a separate lock for each node as there is no generic lock available for the caller to protect the node easily. As we currently don't know whether an object may be used for mmap(), we have to do access management for all objects. If it turns out to slow down handle creation/deletion significantly, we can optimize it in several ways: - Most times only a single filp is added per bo so we could use a static "struct file *main_filp" which is checked/added/removed first before we fall back to the rbtree+drm_vma_offset_file. This could be even done lockless with rcu. - Let user-space pass a hint whether mmap() should be supported on the bo and avoid access-management if not. - .. there are probably more ideas once we have benchmarks .. v2: add drm_vma_node_verify_access() helper Signed-off-by:
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- 22 Aug, 2013 1 commit
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git://github.com/patjak/drm-gma500Dave Airlie authored
Here's some gma500 unifying and cleanups for drm-next. There is more stuff in the pipe for 3.12 but I'd like to get these out of the way first. * 'gma500-next' of git://github.com/patjak/drm-gma500: (35 commits) drm/gma500/cdv: Add and hook up chip op for disabling sr drm/gma500/cdv: Add and hook up chip op for watermarks drm/gma500: Rename psb_intel_encoder to gma_encoder drm/gma500: Rename psb_intel_connector to gma_connector drm/gma500: Rename psb_intel_crtc to gma_crtc drm/gma500/cdv: Convert to generic set_config() drm/gma500/psb: Convert to generic set_config() drm/gma500: Add generic set_config() function drm/gma500/cdv: Convert to generic save/restore drm/gma500/psb: Convert to generic save/restore drm/gma500: Add generic crtc save/restore funcs drm/gma500: Convert to generic encoder funcs drm/gma500: Add generic encoder functions drm/gma500/psb: Convert to generic cursor funcs drm/gma500/cdv: Convert to generic cursor funcs drm/gma500: Add generic cursor functions drm/gma500/psb: Convert to generic crtc->destroy drm/gma500/mdfld: Use identical generic crtc funcs drm/gma500/oak: Use identical generic crtc funcs drm/gma500/psb: Convert to gma_crtc_dpms() ...
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- 21 Aug, 2013 21 commits
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Daniel Vetter authored
... not only when the dma-buf is freshly created. In contrived examples someone else could have exported/imported the dma-buf already and handed us the gem object with a flink name. If such on object gets reexported as a dma_buf we won't have it in the handle cache already, which breaks the guarantee that for dma-buf imports we always hand back an existing handle if there is one. This is exercised by igt/prime_self_import/with_one_bo_two_files Now if we extend the locked sections just a notch more we can also plug th racy buf/handle cache setup in handle_to_fd: If evil userspace races a concurrent gem close against a prime export operation we can end up tearing down the gem handle before the dma buf handle cache is set up. When handle_to_fd gets around to adding the handle to the cache there will be no one left to clean it up, effectily leaking the bo (and the dma-buf, since the handle cache holds a ref on the dma-buf): Thread A Thread B handle_to_fd: lookup gem object from handle creates new dma_buf gem_close on the same handle obj->dma_buf is set, but file priv buf handle cache has no entry obj->handle_count drops to 0 drm_prime_add_buf_handle sets up the handle cache -> We have a dma-buf reference in the handle cache, but since the handle_count of the gem object already dropped to 0 no on will clean it up. When closing the drm device fd we'll hit the WARN_ON in drm_prime_destroy_file_private. The important change is to extend the critical section of the filp->prime.lock to cover the gem handle lookup. This serializes with a concurrent gem handle close. This leak is exercised by igt/prime_self_import/export-vs-gem_close-race Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by:
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Daniel Vetter authored
... and move it to the top of the function to avoid a forward declaration. Signed-off-by:
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Daniel Vetter authored
with the reworking semantics and locking of the obj->dma_buf pointer this pointer is always set as long as there's still a gem handle around and a dma_buf associated with this gem object. Also, the per file-priv lookup-cache for dma-buf importing is also unified between foreign and native objects. Hence we don't need to special case the clean any more and can simply drop the clause which only runs for foreing objects, i.e. with obj->import_attach set. Note that with this change (actually with the previous one to always set up obj->dma_buf even for foreign objects) it is no longer required to set obj->import_attach when importing a foreing object. So update comments accordingly, too. Signed-off-by:
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Daniel Vetter authored
The export dma-buf cache is semantically similar to an flink name. So semantically it makes sense to treat it the same and remove the name (i.e. the dma_buf pointer) and its references when the last gem handle disappears. Again we need to be careful, but double so: Not just could someone race and export with a gem close ioctl (so we need to recheck obj->handle_count again when assigning the new name), but multiple exports can also race against each another. This is prevented by holding the dev->object_name_lock across the entire section which touches obj->dma_buf. With the new scheme we also need to reinstate the obj->dma_buf link at import time (in case the only reference userspace has held in-between was through the dma-buf fd and not through any native gem handle). For simplicity we don't check whether it's a native object but unconditionally set up that link - with the new scheme of removing the obj->dma_buf reference when the last handle disappears we can do that. To make it clear that this is not just for exported buffers anymore als rename it from export_dma_buf to dma_buf. To make sure that now one can race a fd_to_handle or handle_to_fd with gem_close we use the same tricks as in flink of extending the dev->object_name_locking critical section. With this change we finally have a guaranteed 1:1 relationship (at least for native objects) between gem objects and dma-bufs, even accounting for races (which can happen since the dma-buf itself holds a reference while in-flight). This prevent igt/prime_self_import/export-vs-gem_close-race from Oopsing the kernel. There is still a leak though since the per-file priv dma-buf/handle cache handling is racy. That will be fixed in a later patch. v2: Remove the bogus dma_buf_put from the export_and_register_object failure path if we've raced with the handle count dropping to 0. Signed-off-by:
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Daniel Vetter authored
The gem flink name holds a reference onto the object itself, and this self-reference would prevent an flink'ed object from every being freed. To break that loop we remove the flink name when the last userspace handle disappears, i.e. when obj->handle_count reaches 0. Now in gem_open we drop the dev->object_name_lock between the flink name lookup and actually adding the handle. This means a concurrent gem_close of the last handle could result in the flink name getting reaped right inbetween, i.e. Thread 1 Thread 2 gem_open gem_close flink -> obj lookup handle_count drops to 0 remove flink name create_handle handle_count++ If someone now flinks this object again, we'll get a new flink name. We can close this race by removing the lock dropping and making the entire lookup+handle_create sequence atomic. Unfortunately to still be able to share the handle_create logic this requires a handle_create_tail function which drops the lock - we can't hold the object_name_lock while calling into a driver's ->gem_open callback. Note that for flink fixing this race isn't really important, since racing gem_open against gem_close is clearly a userspace bug. And no matter how the race ends, we won't leak any references. But with dma-buf where the userspace dma-buf fd itself is refcounted this is a valid sequence and hence we should fix it. Therefore this patch here is just a warm-up exercise (and for consistency between flink buffer sharing and dma-buf buffer sharing with self-imports). Also note that this extension of the critical section in gem_open protected by dev->object_name_lock only works because it's now a mutex: A spinlock would conflict with the potential memory allocation in idr_preload(). This is exercises by igt/gem_flink_race/flink_name. Signed-off-by:
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Daniel Vetter authored
I want to wrap the creation of a dma-buf from a gem object in it, so that the obj->export_dma_buf cache can be atomically filled in. Instead of creating a new mutex just for that variable I've figured I can reuse the existing dev->object_name_lock, especially since the new semantics will exactly mirror the flink obj->name already protected by that lock. v2: idr_preload/idr_preload_end is now an atomic section, so need to move the mutex locking outside. [airlied: fix up conflict with patch to make debugfs use lock] Signed-off-by:
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Daniel Vetter authored
if (!ret) implies that ret == 0, so no need to clear it again. And explicitly check for ret == 0 to indicate that we're checking an errno integer. Signed-off-by:
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Daniel Vetter authored
When exporting a gem object as a dma-buf the critical section for the per-fd prime lock is just the adding (and in case of errors, removing) of the handle to the per-fd lookup cache. So restrict the critical section to just that part of the function. This simplifies later reordering. Signed-off-by:
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Daniel Vetter authored
Part of the function uses the properly-typed dmabuf variable, the other an untyped void *buf. Kill the later. Signed-off-by:
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Daniel Vetter authored
No one outside of drm should use this, the official interfaces are drm_gem_handle_create and drm_gem_handle_delete. The handle refcounting is purely an implementation detail of gem. Signed-off-by:
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Daniel Vetter authored
handle_unreference only clears up the obj->name and the reference, but would leave a dangling handle in the idr. The right thing to do is to call handle_delete. Signed-off-by:
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Daniel Vetter authored
This is the 2nd attempt, I've always been a bit dissatisified with the tricky nature of the first one: http://lists.freedesktop.org/archives/dri-devel/2012-July/025451.html The issue is that the flink ioctl can race with calling gem_close on the last gem handle. In that case we'll end up with a zero handle count, but an flink name (and it's corresponding reference). Which results in a neat space leak. In my first attempt I've solved this by rechecking the handle count. But fundamentally the issue is that ->handle_count isn't your usual refcount - it can be resurrected from 0 among other things. For those special beasts atomic_t often suggest way more ordering that it actually guarantees. To prevent being tricked by those hairy semantics take the easy way out and simply protect the handle with the existing dev->object_name_lock. With that change implemented it's dead easy to fix the flink vs. gem close reace: When we try to create the name we simply have to check whether there's still officially a gem handle around and if not refuse to create the flink name. Since the handle count decrement and flink name destruction is now also protected by that lock the reace is gone and we can't ever leak the flink reference again. Outside of the drm core only the exynos driver looks at the handle count, and tbh I have no idea why (it's just for debug dmesg output luckily). I've considered inlining the drm_gem_object_handle_free, but I plan to add more name-like things (like the exported dma_buf) to this scheme, so it's clearer to leave the handle freeing in its own function. This is exercised by the new gem_flink_race i-g-t testcase, which on my snb leaks gem objects at a rate of roughly 1k objects/s. v2: Fix up the error path handling in handle_create and make it more robust by simply calling object_handle_unreference. v3: Fix up the handle_unreference logic bug - atomic_dec_and_test retursn 1 for 0. Oops. v4: Squash in inlining of drm_gem_object_handle_reference as suggested by Dave Airlie and add a note that we now have a testcase. Cc: Dave Airlie <airlied@gmail.com> Cc: Inki Dae <inki.dae@samsung.com> Signed-off-by:
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Dave Airlie authored
Merge tag 'drm-intel-next-2013-08-09' of git://people.freedesktop.org/~danvet/drm-intel into drm-next Daniel writes: New pile of stuff for -next: - Cleanup of the old crtc helper callbacks, all encoders are now converted to the i915 modeset infrastructure. - Massive amount of wm patches from Ville for ilk, snb, ivb, hsw, this is prep work to eventually get things going for nuclear pageflips where we need to adjust watermarks on the fly. - More vm/vma patches from Ben. This refactoring isn't yet fully rolled out, we miss the execbuf conversion and some of the low-level bind/unbind support code. - Convert our hdmi infoframe code to use the new common helper functions (Damien). This contains some bugfixes for the common infoframe helpers. - Some cruft removal from Damien. - Various smaller bits&pieces all over, as usual. * tag 'drm-intel-next-2013-08-09' of git://people.freedesktop.org/~danvet/drm-intel: (105 commits) drm/i915: Fix FB WM for HSW drm/i915: expose HDMI connectors on port C on BYT drm/i915: fix a limit check in hsw_compute_wm_results() drm/i915: unbreak i915_gem_object_ggtt_unbind() drm/i915: Make intel_set_mode() static drm/i915: Remove intel_modeset_disable() drm/i915: Make intel_encoder_dpms() static drm/i915: Make i915_hangcheck_elapsed() static drm/i915: Fix #endif comment drm/i915: Remove i915_gem_object_check_coherency() drm/i915: Remove stale prototypes drm/i915: List objects allocated from stolen memory in debugfs drm/i915: Always call intel_update_sprite_watermarks() when disabling a plane drm/i915: Pass plane and crtc to intel_update_sprite_watermarks drm/i915: Don't try to disable plane if it's already disabled drm/i915: Pass crtc to our update/disable_plane hooks drm/i915: Split plane watermark parameters into a separate struct drm/i915: Pull some watermarks state into a separate structure drm/i915: Calculate max watermark levels for ILK+ drm/i915: Rename hsw_lp_wm_result to intel_wm_level ...
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Lespiau, Damien authored
It's only used in drm_platform.c. Signed-off-by:
Damien Lespiau <damien.lespiau@intel.com> Reviewed-by:
Alex Deucher <alexander.deucher@amd.com> Signed-off-by:
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Lespiau, Damien authored
Signed-off-by:
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Lespiau, Damien authored
This function is only used in drm_fb_cma_helper.c. Signed-off-by:
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Lespiau, Damien authored
These were introduced in the very first DRM commit: commit f453ba04 Author: Dave Airlie <airlied@redhat.com> Date: Fri Nov 7 14:05:41 2008 -0800 DRM: add mode setting support Add mode setting support to the DRM layer. But are unused. Signed-off-by:
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Lespiau, Damien authored
It's only used in drm_crtc.c. Signed-off-by:
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Lespiau, Damien authored
The last user was removed in commit 575dc34e Author: Dave Airlie <airlied@redhat.com> Date: Mon Sep 7 18:43:26 2009 +1000 drm/kms: remove old std mode fallback code. The new code adds modes in the helper, which makes more sense I disliked the non-driver code adding modes. Signed-off-by:
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Lespiau, Damien authored
This was last used by nouveau, replaced by a driver-specific property in: commit de691855 Author: Ben Skeggs <bskeggs@redhat.com> Date: Mon Oct 17 12:23:41 2011 +1000 drm/nouveau: improve dithering properties, and implement proper auto mode Signed-off-by:
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Lespiau, Damien authored
A few prototypes have been left in the headers, their function friends long gone. Signed-off-by:
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- 19 Aug, 2013 16 commits
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Daniel Vetter authored
We kzalloc this structure, and for real kms devices we should never loose track of things really. But ums/legacy drivers rely on the drm core to clean up a bit of cruft between lastclose and firstopen (i.e. when X is being restarted), so keep this around. But give it a clear drm_legacy_ prefix and conditionalize the code on !DRIVER_MODESET. Cc: David Herrmann <dh.herrmann@gmail.com> Signed-off-by:
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Daniel Vetter authored
So almost two years ago I've tried to nuke the procfs code already once before: http://lists.freedesktop.org/archives/dri-devel/2011-October/015707.html The conclusion was that userspace drivers (specifically libdrm device node detection) stopped relying on procfs in 2001. But after some digging it turned out that the drmstat tool in libdrm is still using those files (but only when certain options are set). So we've decided to keep profcs. But I when I've started to dig around again what exactly this tool does I've noticed that it tries to read the "mem", "vm", and "vma" files from procfs. Now as far my git history digging shows "mem" never did anything useful (at least in the version that first showed up in upstream history in 2004) and the file was remove in commit 955b12de Author: Ben Gamari <bgamari@gmail.com> Date: Tue Feb 17 20:08:49 2009 -0500 drm: Convert proc files to seq_file and introduce debugfs Which means that for over 4 years drmstat has been broken, and no one cared. In my opinion that's proof enough that no one is actually using drmstat, and so that we can savely nuke the procfs support from drm. While at it fix up the error case cleanup for debugfs in drm_get_minor. v2: Fix dates, libdrm stopped relying on procfs for drm node detection in 2001. v3: fixup compilation warning for !CONFIG_DEBUG_FS, reported by Fengguang Wu. Cc: kbuild test robot <fengguang.wu@intel.com> Cc: Dave Airlie <airlied@linux.ie> Signed-off-by:
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Daniel Vetter authored
It has way too much potential for driver writers to do stupid things like delayed hw setup because the load sequence is somehow racy (e.g. the imx driver in staging). So don't call it for modesetting drivers, which reduces the complexity of the drm core -> driver interface a notch. v2: Don't forget to update DocBook. v3: Go with Laurent's slightly more elaborate proposal for the DocBook update. Add a few words on top of his diff to elaborate a bit on what KMS drivers should and shouldn't do in lastclose. There was already a paragraph present talking about restoring properties, I've simply extended that one. Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by:
Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by:
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Daniel Vetter authored
So if we survey kms drivers there's a bunch of things they commonly do in ->lastclose - delayed processing of vga switcheroo requests (i915, nouveau, radeon) - force-restoring the fbcon (most) - resetting a bunch properties to make fbcon work better (omap) - disabling all outputs (vmwgfx) In short besides the semantically important vga switcheroo stuff they all try very hard to keep fbcon working in case X dies. But none of them try to not do this at driver unload time safe for vmwgfx, and digging through logs I couldn't find any reason for why vmwgfx is special. Since ->firstopen has lots of potential for abuse with kms drivers (like delaying driver setup to pamper over races in the load sequence) it's imo very much worth it to remove this logic so that we can stop using the ->firstopen callback for kms drivers. Also module unloading is rather a debug feature and developers should know how to restore the display to a sane configuration. Cc: Jakob Bornecrantz <jakob@vmware.com> Signed-off-by:
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Daniel Vetter authored
This thing seems to do some kind of delayed setup. Really, real kms drivers shouldn't do that at all. Either stuff needs to be dynamically hotplugged or the driver setup sequence needs to be fixed. This patch here just moves the setup at the very end of the driver load callback, with the locking adjusted accordingly. v2: Also move the corresponding put from ->lastclose to ->unload. Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by:
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Kristian Høgsberg authored
Currently, both ranges overlap. Fix the limits so both ranges are mutually exclusive. Also use the occasion to convert whitespaces to tabs. Signed-off-by:
Kristian Høgsberg <krh@bitplanet.net> (fixed up tabs and adjust commit-msg accordingly) Signed-off-by:
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Daniel Vetter authored
The idr is protected with our spinlock, if we don't hold that nothing prevents the gem objects from disappearing from under us. Signed-off-by:
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Daniel Vetter authored
We might as well have a real ioctl function which checks for the callbacks. This seems to be a remnant from back in the days when each drm driver had their own complete ioctl table, with no shared core drm table at all. To make really sure no mis-guided user in a kms driver pops up again explicitly check for that in the new ioctl implementation. v2: Drop the unused variable I've accidentally left in the code, spotted by David Herrmann. Cc: David Herrmann <dh.herrmann@gmail.com> Signed-off-by:
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Daniel Vetter authored
I've forgotten this and shuffling all the little pieces into the respective patches is rather cumbersome ... Signed-off-by:
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Daniel Vetter authored
The new arch_phys_wc_add/del functions do the right thing both with and without MTRR support in the kernel. So we can drop these additional checks. David Herrmann suggest to also kill the DRIVER_USE_MTRR flag since it's now unused, which spurred me to do a bit a better audit of the affected drivers. David helped a lot in that. Quoting our mail discussion: On Wed, Jul 10, 2013 at 5:41 PM, David Herrmann <dh.herrmann@gmail.com> wrote: > On Wed, Jul 10, 2013 at 5:22 PM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: >> On Wed, Jul 10, 2013 at 3:51 PM, David Herrmann <dh.herrmann@gmail.com> wrote: >>>> -#if __OS_HAS_MTRR >>>> -static inline int drm_core_has_MTRR(struct drm_device *dev) >>>> -{ >>>> - return drm_core_check_feature(dev, DRIVER_USE_MTRR); >>>> -} >>>> -#else >>>> -#define drm_core_has_MTRR(dev) (0) >>>> -#endif >>>> - >>> >>> That was the last user of DRIVER_USE_MTRR (apart from drivers setting >>> it in .driver_features). Any reason to keep it around? >> >> Yeah, I guess we could rip things out. Which will also force me to >> properly audit drivers for the eventual behaviour change this could >> entail (in case there's an x86 driver which did not ask for an mtrr, >> but iirc there isn't). > > david@david-mb ~/dev/kernel/linux $ for i in drivers/gpu/drm/* ; do if > test -d "$i" ; then if ! grep -q USE_MTRR -r $i ; then echo $i ; fi ; > fi ; done > drivers/gpu/drm/exynos > drivers/gpu/drm/gma500 > drivers/gpu/drm/i2c > drivers/gpu/drm/nouveau > drivers/gpu/drm/omapdrm > drivers/gpu/drm/qxl > drivers/gpu/drm/rcar-du > drivers/gpu/drm/shmobile > drivers/gpu/drm/tilcdc > drivers/gpu/drm/ttm > drivers/gpu/drm/udl > drivers/gpu/drm/vmwgfx > david@david-mb ~/dev/kernel/linux $ > > So for x86 gma500,nouveau,qxl,udl,vmwgfx don't set DRIVER_USE_MTRR. > But I cannot tell whether they break if we call arch_phys_wc_add/del, > anyway. At least nouveau seemed to work here, but it doesn't use AGP > or drm_bufs, I guess. Cool, thanks a lot for stitching together the list of drivers to look at. So for real KMS drivers it's the drives responsibility to add an mtrr if it needs one. nouvea, radeon, mgag200, i915 and vmwgfx do that already. Somehow the savage driver also ends up doing that, I have no idea why. Note that gma500 as a pure KMS driver doesn't need MTRR setup since the platforms that it supports all support PAT. So no MTRRs needed to get wc iomappings. The mtrr support in the drm core is all for legacy mappings of garts, framebuffers and registers. All legacy drivers set the USE_MTRR flag, so we're good there. All in all I think we can really just ditch this /endquote v2: Also kill DRIVER_USE_MTRR as suggested by David Herrmann v3: Rebase on top of David Herrmann's agp setup/cleanup changes. Cc: David Herrmann <dh.herrmann@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by:Andy Lutomirski <luto@amacapital.net> Reviewed-by:
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Daniel Vetter authored
Trying to drop a reference we don't have is a pretty serious bug. Trying to paper over it is an even worse offense. So scream into dmesg with a big WARN in case that ever happens. Signed-off-by:
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Daniel Vetter authored
Calling this function with a NULL object is simply a bug, so papering over a NULL object not a good idea. Signed-off-by:
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Daniel Vetter authored
We have three callers of this function now and it's neither performance critical nor really small. So an inline function feels like overkill and unecessarily separates the different parts of the code. Since all callers of drm_gem_object_handle_free are now in drm_gem.c we can make that static (and remove the unused EXPORT_SYMBOL). To avoid a forward declaration move it (and drm_gem_object_free_bug) up a bit. Signed-off-by:
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Daniel Vetter authored
Lifetime rules seem to be solid around ->import_attach. So this patch just properly documents them. Note that pointing directly at the attachment might have issues for devices that have multiple struct device *dev parts constituting the logical gpu and so might need multiple attachment points. Similarly for drm devices which don't need a dma attachment at all (like udl). But fixing that up is material for different patches. Reviewed-by:
Rob Clark <robdclark@gmail.com> Signed-off-by:
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Daniel Vetter authored
I've checked both implementations (radeon/nouveau) and they both grab the page array from ttm simply by dereferencing it and then wrapping it up with drm_prime_pages_to_sg in the callback and map it with dma_map_sg (in the helper). Only the grabbing of the underlying page array is anything we need to be concerned about, and either those pages are pinned independently, or we're screwed no matter what. And indeed, nouveau/radeon pin the backing storage in their attach/detach functions. Since I've created this patch cma prime support for dma_buf was added. drm_gem_cma_prime_get_sg_table only calls kzalloc and the creates&maps the sg table with dma_get_sgtable. It doesn't touch any gem object state otherwise. So the cma helpers also look safe. The only thing we might claim it does is prevent concurrent mapping of dma_buf attachments. But a) that's not allowed and b) the current code is racy already since it checks whether the sg mapping exists _before_ grabbing the lock. So the dev->struct_mutex locking here does absolutely nothing useful, but only distracts. Remove it. This should also help Maarten's work to eventually pin the backing storage more dynamically by preventing locking inversions around dev->struct_mutex. v2: Add analysis for recently added cma helper prime code. Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by:
Maarten Lankhorst <maarten.lankhorst@canonical.com> Signed-off-by:
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Inki Dae authored
Signed-off-by:
Inki Dae <inki.dae@samsung.com> Signed-off-by:
Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by:
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