1 /* 2 * linux/drivers/video/fb_defio.c 3 * 4 * Copyright (C) 2006 Jaya Kumar 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file COPYING in the main directory of this archive 8 * for more details. 9 */ 10 11 #include <linux/module.h> 12 #include <linux/kernel.h> 13 #include <linux/errno.h> 14 #include <linux/string.h> 15 #include <linux/mm.h> 16 #include <linux/vmalloc.h> 17 #include <linux/delay.h> 18 #include <linux/interrupt.h> 19 #include <linux/fb.h> 20 #include <linux/list.h> 21 22 /* to support deferred IO */ 23 #include <linux/rmap.h> 24 #include <linux/pagemap.h> 25 26 static struct page *fb_deferred_io_get_page(struct fb_info *info, unsigned long offs) 27 { 28 struct fb_deferred_io *fbdefio = info->fbdefio; 29 const void *screen_buffer = info->screen_buffer; 30 struct page *page = NULL; 31 32 if (fbdefio->get_page) 33 return fbdefio->get_page(info, offs); 34 35 if (is_vmalloc_addr(screen_buffer + offs)) 36 page = vmalloc_to_page(screen_buffer + offs); 37 else if (info->fix.smem_start) 38 page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT); 39 40 if (page) 41 get_page(page); 42 43 return page; 44 } 45 46 static struct fb_deferred_io_pageref *fb_deferred_io_pageref_lookup(struct fb_info *info, 47 unsigned long offset, 48 struct page *page) 49 { 50 unsigned long pgoff = offset >> PAGE_SHIFT; 51 struct fb_deferred_io_pageref *pageref; 52 53 if (fb_WARN_ON_ONCE(info, pgoff >= info->npagerefs)) 54 return NULL; /* incorrect allocation size */ 55 56 /* 1:1 mapping between pageref and page offset */ 57 pageref = &info->pagerefs[pgoff]; 58 59 if (pageref->page) 60 goto out; 61 62 pageref->page = page; 63 pageref->offset = pgoff << PAGE_SHIFT; 64 INIT_LIST_HEAD(&pageref->list); 65 66 out: 67 if (fb_WARN_ON_ONCE(info, pageref->page != page)) 68 return NULL; /* inconsistent state */ 69 return pageref; 70 } 71 72 static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info *info, 73 unsigned long offset, 74 struct page *page) 75 { 76 struct fb_deferred_io *fbdefio = info->fbdefio; 77 struct list_head *pos = &fbdefio->pagereflist; 78 struct fb_deferred_io_pageref *pageref, *cur; 79 80 pageref = fb_deferred_io_pageref_lookup(info, offset, page); 81 if (!pageref) 82 return NULL; 83 84 /* 85 * This check is to catch the case where a new process could start 86 * writing to the same page through a new PTE. This new access 87 * can cause a call to .page_mkwrite even if the original process' 88 * PTE is marked writable. 89 */ 90 if (!list_empty(&pageref->list)) 91 goto pageref_already_added; 92 93 if (unlikely(fbdefio->sort_pagereflist)) { 94 /* 95 * We loop through the list of pagerefs before adding in 96 * order to keep the pagerefs sorted. This has significant 97 * overhead of O(n^2) with n being the number of written 98 * pages. If possible, drivers should try to work with 99 * unsorted page lists instead. 100 */ 101 list_for_each_entry(cur, &fbdefio->pagereflist, list) { 102 if (cur->offset > pageref->offset) 103 break; 104 } 105 pos = &cur->list; 106 } 107 108 list_add_tail(&pageref->list, pos); 109 110 pageref_already_added: 111 return pageref; 112 } 113 114 static void fb_deferred_io_pageref_put(struct fb_deferred_io_pageref *pageref, 115 struct fb_info *info) 116 { 117 list_del_init(&pageref->list); 118 } 119 120 /* this is to find and return the vmalloc-ed fb pages */ 121 static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf) 122 { 123 unsigned long offset; 124 struct page *page; 125 struct fb_info *info = vmf->vma->vm_private_data; 126 127 offset = vmf->pgoff << PAGE_SHIFT; 128 if (offset >= info->fix.smem_len) 129 return VM_FAULT_SIGBUS; 130 131 page = fb_deferred_io_get_page(info, offset); 132 if (!page) 133 return VM_FAULT_SIGBUS; 134 135 if (!vmf->vma->vm_file) 136 fb_err(info, "no mapping available\n"); 137 138 BUG_ON(!info->fbdefio->mapping); 139 140 vmf->page = page; 141 return 0; 142 } 143 144 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync) 145 { 146 struct fb_info *info = file->private_data; 147 struct inode *inode = file_inode(file); 148 int err = file_write_and_wait_range(file, start, end); 149 if (err) 150 return err; 151 152 /* Skip if deferred io is compiled-in but disabled on this fbdev */ 153 if (!info->fbdefio) 154 return 0; 155 156 inode_lock(inode); 157 flush_delayed_work(&info->deferred_work); 158 inode_unlock(inode); 159 160 return 0; 161 } 162 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 163 164 /* 165 * Adds a page to the dirty list. Call this from struct 166 * vm_operations_struct.page_mkwrite. 167 */ 168 static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset, 169 struct page *page) 170 { 171 struct fb_deferred_io *fbdefio = info->fbdefio; 172 struct fb_deferred_io_pageref *pageref; 173 vm_fault_t ret; 174 175 /* protect against the workqueue changing the page list */ 176 mutex_lock(&fbdefio->lock); 177 178 pageref = fb_deferred_io_pageref_get(info, offset, page); 179 if (WARN_ON_ONCE(!pageref)) { 180 ret = VM_FAULT_OOM; 181 goto err_mutex_unlock; 182 } 183 184 /* 185 * We want the page to remain locked from ->page_mkwrite until 186 * the PTE is marked dirty to avoid mapping_wrprotect_range() 187 * being called before the PTE is updated, which would leave 188 * the page ignored by defio. 189 * Do this by locking the page here and informing the caller 190 * about it with VM_FAULT_LOCKED. 191 */ 192 lock_page(pageref->page); 193 194 mutex_unlock(&fbdefio->lock); 195 196 /* come back after delay to process the deferred IO */ 197 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 198 return VM_FAULT_LOCKED; 199 200 err_mutex_unlock: 201 mutex_unlock(&fbdefio->lock); 202 return ret; 203 } 204 205 /* 206 * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O 207 * @fb_info: The fbdev info structure 208 * @vmf: The VM fault 209 * 210 * This is a callback we get when userspace first tries to 211 * write to the page. We schedule a workqueue. That workqueue 212 * will eventually mkclean the touched pages and execute the 213 * deferred framebuffer IO. Then if userspace touches a page 214 * again, we repeat the same scheme. 215 * 216 * Returns: 217 * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise. 218 */ 219 static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf) 220 { 221 unsigned long offset = vmf->pgoff << PAGE_SHIFT; 222 struct page *page = vmf->page; 223 224 file_update_time(vmf->vma->vm_file); 225 226 return fb_deferred_io_track_page(info, offset, page); 227 } 228 229 /* vm_ops->page_mkwrite handler */ 230 static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) 231 { 232 struct fb_info *info = vmf->vma->vm_private_data; 233 234 return fb_deferred_io_page_mkwrite(info, vmf); 235 } 236 237 static const struct vm_operations_struct fb_deferred_io_vm_ops = { 238 .fault = fb_deferred_io_fault, 239 .page_mkwrite = fb_deferred_io_mkwrite, 240 }; 241 242 static const struct address_space_operations fb_deferred_io_aops = { 243 .dirty_folio = noop_dirty_folio, 244 }; 245 246 int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 247 { 248 vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); 249 250 vma->vm_ops = &fb_deferred_io_vm_ops; 251 vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP); 252 if (!(info->flags & FBINFO_VIRTFB)) 253 vm_flags_set(vma, VM_IO); 254 vma->vm_private_data = info; 255 return 0; 256 } 257 EXPORT_SYMBOL_GPL(fb_deferred_io_mmap); 258 259 /* workqueue callback */ 260 static void fb_deferred_io_work(struct work_struct *work) 261 { 262 struct fb_info *info = container_of(work, struct fb_info, deferred_work.work); 263 struct fb_deferred_io_pageref *pageref, *next; 264 struct fb_deferred_io *fbdefio = info->fbdefio; 265 266 /* here we wrprotect the page's mappings, then do all deferred IO. */ 267 mutex_lock(&fbdefio->lock); 268 #ifdef CONFIG_MMU 269 list_for_each_entry(pageref, &fbdefio->pagereflist, list) { 270 struct page *page = pageref->page; 271 pgoff_t pgoff = pageref->offset >> PAGE_SHIFT; 272 273 mapping_wrprotect_range(fbdefio->mapping, pgoff, 274 page_to_pfn(page), 1); 275 } 276 #endif 277 278 /* driver's callback with pagereflist */ 279 fbdefio->deferred_io(info, &fbdefio->pagereflist); 280 281 /* clear the list */ 282 list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list) 283 fb_deferred_io_pageref_put(pageref, info); 284 285 mutex_unlock(&fbdefio->lock); 286 } 287 288 int fb_deferred_io_init(struct fb_info *info) 289 { 290 struct fb_deferred_io *fbdefio = info->fbdefio; 291 struct fb_deferred_io_pageref *pagerefs; 292 unsigned long npagerefs; 293 int ret; 294 295 BUG_ON(!fbdefio); 296 297 if (WARN_ON(!info->fix.smem_len)) 298 return -EINVAL; 299 300 mutex_init(&fbdefio->lock); 301 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 302 INIT_LIST_HEAD(&fbdefio->pagereflist); 303 if (fbdefio->delay == 0) /* set a default of 1 s */ 304 fbdefio->delay = HZ; 305 306 npagerefs = DIV_ROUND_UP(info->fix.smem_len, PAGE_SIZE); 307 308 /* alloc a page ref for each page of the display memory */ 309 pagerefs = kvcalloc(npagerefs, sizeof(*pagerefs), GFP_KERNEL); 310 if (!pagerefs) { 311 ret = -ENOMEM; 312 goto err; 313 } 314 info->npagerefs = npagerefs; 315 info->pagerefs = pagerefs; 316 317 return 0; 318 319 err: 320 mutex_destroy(&fbdefio->lock); 321 return ret; 322 } 323 EXPORT_SYMBOL_GPL(fb_deferred_io_init); 324 325 void fb_deferred_io_open(struct fb_info *info, 326 struct inode *inode, 327 struct file *file) 328 { 329 struct fb_deferred_io *fbdefio = info->fbdefio; 330 331 fbdefio->mapping = file->f_mapping; 332 file->f_mapping->a_ops = &fb_deferred_io_aops; 333 fbdefio->open_count++; 334 } 335 EXPORT_SYMBOL_GPL(fb_deferred_io_open); 336 337 static void fb_deferred_io_lastclose(struct fb_info *info) 338 { 339 flush_delayed_work(&info->deferred_work); 340 } 341 342 void fb_deferred_io_release(struct fb_info *info) 343 { 344 struct fb_deferred_io *fbdefio = info->fbdefio; 345 346 if (!--fbdefio->open_count) 347 fb_deferred_io_lastclose(info); 348 } 349 EXPORT_SYMBOL_GPL(fb_deferred_io_release); 350 351 void fb_deferred_io_cleanup(struct fb_info *info) 352 { 353 struct fb_deferred_io *fbdefio = info->fbdefio; 354 355 fb_deferred_io_lastclose(info); 356 357 kvfree(info->pagerefs); 358 mutex_destroy(&fbdefio->lock); 359 fbdefio->mapping = NULL; 360 } 361 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); 362