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