pvr_gem.c

  1// SPDX-License-Identifier: GPL-2.0-only OR MIT
  2/* Copyright (c) 2023 Imagination Technologies Ltd. */
  3
  4#include "pvr_device.h"
  5#include "pvr_gem.h"
  6#include "pvr_vm.h"
  7
  8#include <drm/drm_gem.h>
  9#include <drm/drm_prime.h>
 10
 11#include <linux/compiler.h>
 12#include <linux/compiler_attributes.h>
 13#include <linux/dma-buf.h>
 14#include <linux/dma-direction.h>
 15#include <linux/dma-mapping.h>
 16#include <linux/err.h>
 17#include <linux/gfp.h>
 18#include <linux/iosys-map.h>
 19#include <linux/log2.h>
 20#include <linux/mutex.h>
 21#include <linux/pagemap.h>
 22#include <linux/property.h>
 23#include <linux/refcount.h>
 24#include <linux/scatterlist.h>
 25
 26static void pvr_gem_object_free(struct drm_gem_object *obj)
 27{
 28	drm_gem_shmem_object_free(obj);
 29}
 30
 31static struct dma_buf *pvr_gem_export(struct drm_gem_object *obj, int flags)
 32{
 33	struct pvr_gem_object *pvr_obj = gem_to_pvr_gem(obj);
 34
 35	if (pvr_obj->flags & DRM_PVR_BO_PM_FW_PROTECT)
 36		return ERR_PTR(-EPERM);
 37
 38	return drm_gem_prime_export(obj, flags);
 39}
 40
 41static int pvr_gem_mmap(struct drm_gem_object *gem_obj, struct vm_area_struct *vma)
 42{
 43	struct pvr_gem_object *pvr_obj = gem_to_pvr_gem(gem_obj);
 44	struct drm_gem_shmem_object *shmem_obj = shmem_gem_from_pvr_gem(pvr_obj);
 45
 46	if (!(pvr_obj->flags & DRM_PVR_BO_ALLOW_CPU_USERSPACE_ACCESS))
 47		return -EINVAL;
 48
 49	return drm_gem_shmem_mmap(shmem_obj, vma);
 50}
 51
 52static const struct drm_gem_object_funcs pvr_gem_object_funcs = {
 53	.free = pvr_gem_object_free,
 54	.print_info = drm_gem_shmem_object_print_info,
 55	.export = pvr_gem_export,
 56	.pin = drm_gem_shmem_object_pin,
 57	.unpin = drm_gem_shmem_object_unpin,
 58	.get_sg_table = drm_gem_shmem_object_get_sg_table,
 59	.vmap = drm_gem_shmem_object_vmap,
 60	.vunmap = drm_gem_shmem_object_vunmap,
 61	.mmap = pvr_gem_mmap,
 62	.vm_ops = &drm_gem_shmem_vm_ops,
 63};
 64
 65/**
 66 * pvr_gem_object_flags_validate() - Verify that a collection of PowerVR GEM
 67 * mapping and/or creation flags form a valid combination.
 68 * @flags: PowerVR GEM mapping/creation flags to validate.
 69 *
 70 * This function explicitly allows kernel-only flags. All ioctl entrypoints
 71 * should do their own validation as well as relying on this function.
 72 *
 73 * Return:
 74 *  * %true if @flags contains valid mapping and/or creation flags, or
 75 *  * %false otherwise.
 76 */
 77static bool
 78pvr_gem_object_flags_validate(u64 flags)
 79{
 80	static const u64 invalid_combinations[] = {
 81		/*
 82		 * Memory flagged as PM/FW-protected cannot be mapped to
 83		 * userspace. To make this explicit, we require that the two
 84		 * flags allowing each of these respective features are never
 85		 * specified together.
 86		 */
 87		(DRM_PVR_BO_PM_FW_PROTECT |
 88		 DRM_PVR_BO_ALLOW_CPU_USERSPACE_ACCESS),
 89	};
 90
 91	/*
 92	 * Check for bits set in undefined regions. Reserved regions refer to
 93	 * options that can only be set by the kernel. These are explicitly
 94	 * allowed in most cases, and must be checked specifically in IOCTL
 95	 * callback code.
 96	 */
 97	if ((flags & PVR_BO_UNDEFINED_MASK) != 0)
 98		return false;
 99
100	/*
101	 * Check for all combinations of flags marked as invalid in the array
102	 * above.
103	 */
104	for (int i = 0; i < ARRAY_SIZE(invalid_combinations); ++i) {
105		u64 combo = invalid_combinations[i];
106
107		if ((flags & combo) == combo)
108			return false;
109	}
110
111	return true;
112}
113
114/**
115 * pvr_gem_object_into_handle() - Convert a reference to an object into a
116 * userspace-accessible handle.
117 * @pvr_obj: [IN] Target PowerVR-specific object.
118 * @pvr_file: [IN] File to associate the handle with.
119 * @handle: [OUT] Pointer to store the created handle in. Remains unmodified if
120 * an error is encountered.
121 *
122 * If an error is encountered, ownership of @pvr_obj will not have been
123 * transferred. If this function succeeds, however, further use of @pvr_obj is
124 * considered undefined behaviour unless another reference to it is explicitly
125 * held.
126 *
127 * Return:
128 *  * 0 on success, or
129 *  * Any error encountered while attempting to allocate a handle on @pvr_file.
130 */
131int
132pvr_gem_object_into_handle(struct pvr_gem_object *pvr_obj,
133			   struct pvr_file *pvr_file, u32 *handle)
134{
135	struct drm_gem_object *gem_obj = gem_from_pvr_gem(pvr_obj);
136	struct drm_file *file = from_pvr_file(pvr_file);
137
138	u32 new_handle;
139	int err;
140
141	err = drm_gem_handle_create(file, gem_obj, &new_handle);
142	if (err)
143		return err;
144
145	/*
146	 * Release our reference to @pvr_obj, effectively transferring
147	 * ownership to the handle.
148	 */
149	pvr_gem_object_put(pvr_obj);
150
151	/*
152	 * Do not store the new handle in @handle until no more errors can
153	 * occur.
154	 */
155	*handle = new_handle;
156
157	return 0;
158}
159
160/**
161 * pvr_gem_object_from_handle() - Obtain a reference to an object from a
162 * userspace handle.
163 * @pvr_file: PowerVR-specific file to which @handle is associated.
164 * @handle: Userspace handle referencing the target object.
165 *
166 * On return, @handle always maintains its reference to the requested object
167 * (if it had one in the first place). If this function succeeds, the returned
168 * object will hold an additional reference. When the caller is finished with
169 * the returned object, they should call pvr_gem_object_put() on it to release
170 * this reference.
171 *
172 * Return:
173 *  * A pointer to the requested PowerVR-specific object on success, or
174 *  * %NULL otherwise.
175 */
176struct pvr_gem_object *
177pvr_gem_object_from_handle(struct pvr_file *pvr_file, u32 handle)
178{
179	struct drm_file *file = from_pvr_file(pvr_file);
180	struct drm_gem_object *gem_obj;
181
182	gem_obj = drm_gem_object_lookup(file, handle);
183	if (!gem_obj)
184		return NULL;
185
186	return gem_to_pvr_gem(gem_obj);
187}
188
189/**
190 * pvr_gem_object_vmap() - Map a PowerVR GEM object into CPU virtual address
191 * space.
192 * @pvr_obj: Target PowerVR GEM object.
193 *
194 * Once the caller is finished with the CPU mapping, they must call
195 * pvr_gem_object_vunmap() on @pvr_obj.
196 *
197 * If @pvr_obj is CPU-cached, dma_sync_sgtable_for_cpu() is called to make
198 * sure the CPU mapping is consistent.
199 *
200 * Return:
201 *  * A pointer to the CPU mapping on success,
202 *  * -%ENOMEM if the mapping fails, or
203 *  * Any error encountered while attempting to acquire a reference to the
204 *    backing pages for @pvr_obj.
205 */
206void *
207pvr_gem_object_vmap(struct pvr_gem_object *pvr_obj)
208{
209	struct drm_gem_shmem_object *shmem_obj = shmem_gem_from_pvr_gem(pvr_obj);
210	struct drm_gem_object *obj = gem_from_pvr_gem(pvr_obj);
211	struct iosys_map map;
212	int err;
213
214	dma_resv_lock(obj->resv, NULL);
215
216	err = drm_gem_shmem_vmap_locked(shmem_obj, &map);
217	if (err)
218		goto err_unlock;
219
220	if (pvr_obj->flags & PVR_BO_CPU_CACHED) {
221		struct device *dev = shmem_obj->base.dev->dev;
222
223		/* If shmem_obj->sgt is NULL, that means the buffer hasn't been mapped
224		 * in GPU space yet.
225		 */
226		if (shmem_obj->sgt)
227			dma_sync_sgtable_for_cpu(dev, shmem_obj->sgt, DMA_BIDIRECTIONAL);
228	}
229
230	dma_resv_unlock(obj->resv);
231
232	return map.vaddr;
233
234err_unlock:
235	dma_resv_unlock(obj->resv);
236
237	return ERR_PTR(err);
238}
239
240/**
241 * pvr_gem_object_vunmap() - Unmap a PowerVR memory object from CPU virtual
242 * address space.
243 * @pvr_obj: Target PowerVR GEM object.
244 *
245 * If @pvr_obj is CPU-cached, dma_sync_sgtable_for_device() is called to make
246 * sure the GPU mapping is consistent.
247 */
248void
249pvr_gem_object_vunmap(struct pvr_gem_object *pvr_obj)
250{
251	struct drm_gem_shmem_object *shmem_obj = shmem_gem_from_pvr_gem(pvr_obj);
252	struct iosys_map map = IOSYS_MAP_INIT_VADDR(shmem_obj->vaddr);
253	struct drm_gem_object *obj = gem_from_pvr_gem(pvr_obj);
254
255	if (WARN_ON(!map.vaddr))
256		return;
257
258	dma_resv_lock(obj->resv, NULL);
259
260	if (pvr_obj->flags & PVR_BO_CPU_CACHED) {
261		struct device *dev = shmem_obj->base.dev->dev;
262
263		/* If shmem_obj->sgt is NULL, that means the buffer hasn't been mapped
264		 * in GPU space yet.
265		 */
266		if (shmem_obj->sgt)
267			dma_sync_sgtable_for_device(dev, shmem_obj->sgt, DMA_BIDIRECTIONAL);
268	}
269
270	drm_gem_shmem_vunmap_locked(shmem_obj, &map);
271
272	dma_resv_unlock(obj->resv);
273}
274
275/**
276 * pvr_gem_object_zero() - Zeroes the physical memory behind an object.
277 * @pvr_obj: Target PowerVR GEM object.
278 *
279 * Return:
280 *  * 0 on success, or
281 *  * Any error encountered while attempting to map @pvr_obj to the CPU (see
282 *    pvr_gem_object_vmap()).
283 */
284static int
285pvr_gem_object_zero(struct pvr_gem_object *pvr_obj)
286{
287	void *cpu_ptr;
288
289	cpu_ptr = pvr_gem_object_vmap(pvr_obj);
290	if (IS_ERR(cpu_ptr))
291		return PTR_ERR(cpu_ptr);
292
293	memset(cpu_ptr, 0, pvr_gem_object_size(pvr_obj));
294
295	/* Make sure the zero-ing is done before vumap-ing the object. */
296	wmb();
297
298	pvr_gem_object_vunmap(pvr_obj);
299
300	return 0;
301}
302
303/**
304 * pvr_gem_create_object() - Allocate and pre-initializes a pvr_gem_object
305 * @drm_dev: DRM device creating this object.
306 * @size: Size of the object to allocate in bytes.
307 *
308 * Return:
309 *  * The new pre-initialized GEM object on success,
310 *  * -ENOMEM if the allocation failed.
311 */
312struct drm_gem_object *pvr_gem_create_object(struct drm_device *drm_dev, size_t size)
313{
314	struct drm_gem_object *gem_obj;
315	struct pvr_gem_object *pvr_obj;
316
317	pvr_obj = kzalloc(sizeof(*pvr_obj), GFP_KERNEL);
318	if (!pvr_obj)
319		return ERR_PTR(-ENOMEM);
320
321	gem_obj = gem_from_pvr_gem(pvr_obj);
322	gem_obj->funcs = &pvr_gem_object_funcs;
323
324	return gem_obj;
325}
326
327/**
328 * pvr_gem_object_create() - Creates a PowerVR-specific buffer object.
329 * @pvr_dev: Target PowerVR device.
330 * @size: Size of the object to allocate in bytes. Must be greater than zero.
331 * Any value which is not an exact multiple of the system page size will be
332 * rounded up to satisfy this condition.
333 * @flags: Options which affect both this operation and future mapping
334 * operations performed on the returned object. Must be a combination of
335 * DRM_PVR_BO_* and/or PVR_BO_* flags.
336 *
337 * The created object may be larger than @size, but can never be smaller. To
338 * get the exact size, call pvr_gem_object_size() on the returned pointer.
339 *
340 * Return:
341 *  * The newly-minted PowerVR-specific buffer object on success,
342 *  * -%EINVAL if @size is zero or @flags is not valid,
343 *  * -%ENOMEM if sufficient physical memory cannot be allocated, or
344 *  * Any other error returned by drm_gem_create_mmap_offset().
345 */
346struct pvr_gem_object *
347pvr_gem_object_create(struct pvr_device *pvr_dev, size_t size, u64 flags)
348{
349	struct drm_device *drm_dev = from_pvr_device(pvr_dev);
350	struct drm_gem_shmem_object *shmem_obj;
351	struct pvr_gem_object *pvr_obj;
352	struct sg_table *sgt;
353	int err;
354
355	/* Verify @size and @flags before continuing. */
356	if (size == 0 || !pvr_gem_object_flags_validate(flags))
357		return ERR_PTR(-EINVAL);
358
359	if (device_get_dma_attr(drm_dev->dev) == DEV_DMA_COHERENT)
360		flags |= PVR_BO_CPU_CACHED;
361
362	shmem_obj = drm_gem_shmem_create(drm_dev, size);
363	if (IS_ERR(shmem_obj))
364		return ERR_CAST(shmem_obj);
365
366	shmem_obj->pages_mark_dirty_on_put = true;
367	shmem_obj->map_wc = !(flags & PVR_BO_CPU_CACHED);
368	pvr_obj = shmem_gem_to_pvr_gem(shmem_obj);
369	pvr_obj->flags = flags;
370
371	sgt = drm_gem_shmem_get_pages_sgt(shmem_obj);
372	if (IS_ERR(sgt)) {
373		err = PTR_ERR(sgt);
374		goto err_shmem_object_free;
375	}
376
377	dma_sync_sgtable_for_device(drm_dev->dev, sgt, DMA_BIDIRECTIONAL);
378
379	/*
380	 * Do this last because pvr_gem_object_zero() requires a fully
381	 * configured instance of struct pvr_gem_object.
382	 */
383	pvr_gem_object_zero(pvr_obj);
384
385	return pvr_obj;
386
387err_shmem_object_free:
388	drm_gem_shmem_free(shmem_obj);
389
390	return ERR_PTR(err);
391}
392
393/**
394 * pvr_gem_get_dma_addr() - Get DMA address for given offset in object
395 * @pvr_obj: Pointer to object to lookup address in.
396 * @offset: Offset within object to lookup address at.
397 * @dma_addr_out: Pointer to location to store DMA address.
398 *
399 * Returns:
400 *  * 0 on success, or
401 *  * -%EINVAL if object is not currently backed, or if @offset is out of valid
402 *    range for this object.
403 */
404int
405pvr_gem_get_dma_addr(struct pvr_gem_object *pvr_obj, u32 offset,
406		     dma_addr_t *dma_addr_out)
407{
408	struct drm_gem_shmem_object *shmem_obj = shmem_gem_from_pvr_gem(pvr_obj);
409	u32 accumulated_offset = 0;
410	struct scatterlist *sgl;
411	unsigned int sgt_idx;
412
413	WARN_ON(!shmem_obj->sgt);
414	for_each_sgtable_dma_sg(shmem_obj->sgt, sgl, sgt_idx) {
415		u32 new_offset = accumulated_offset + sg_dma_len(sgl);
416
417		if (offset >= accumulated_offset && offset < new_offset) {
418			*dma_addr_out = sg_dma_address(sgl) +
419					(offset - accumulated_offset);
420			return 0;
421		}
422
423		accumulated_offset = new_offset;
424	}
425
426	return -EINVAL;
427}