xref: /linux/drivers/video/fbdev/core/fb_chrdev.c (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/compat.h>
4 #include <linux/console.h>
5 #include <linux/fb.h>
6 #include <linux/fbcon.h>
7 #include <linux/major.h>
8 
9 #include "fb_internal.h"
10 
11 /*
12  * We hold a reference to the fb_info in file->private_data,
13  * but if the current registered fb has changed, we don't
14  * actually want to use it.
15  *
16  * So look up the fb_info using the inode minor number,
17  * and just verify it against the reference we have.
18  */
file_fb_info(struct file * file)19 static struct fb_info *file_fb_info(struct file *file)
20 {
21 	struct inode *inode = file_inode(file);
22 	int fbidx = iminor(inode);
23 	struct fb_info *info = registered_fb[fbidx];
24 
25 	if (info != file->private_data)
26 		info = NULL;
27 	return info;
28 }
29 
fb_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)30 static ssize_t fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
31 {
32 	struct fb_info *info = file_fb_info(file);
33 
34 	if (!info)
35 		return -ENODEV;
36 
37 	if (fb_WARN_ON_ONCE(info, !info->fbops->fb_read))
38 		return -EINVAL;
39 
40 	if (info->state != FBINFO_STATE_RUNNING)
41 		return -EPERM;
42 
43 	return info->fbops->fb_read(info, buf, count, ppos);
44 }
45 
fb_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)46 static ssize_t fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
47 {
48 	struct fb_info *info = file_fb_info(file);
49 
50 	if (!info)
51 		return -ENODEV;
52 
53 	if (fb_WARN_ON_ONCE(info, !info->fbops->fb_write))
54 		return -EINVAL;
55 
56 	if (info->state != FBINFO_STATE_RUNNING)
57 		return -EPERM;
58 
59 	return info->fbops->fb_write(info, buf, count, ppos);
60 }
61 
do_fb_ioctl(struct fb_info * info,unsigned int cmd,unsigned long arg)62 static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
63 			unsigned long arg)
64 {
65 	const struct fb_ops *fb;
66 	struct fb_var_screeninfo var;
67 	struct fb_fix_screeninfo fix;
68 	struct fb_cmap cmap_from;
69 	struct fb_cmap_user cmap;
70 	void __user *argp = (void __user *)arg;
71 	long ret = 0;
72 
73 	switch (cmd) {
74 	case FBIOGET_VSCREENINFO:
75 		lock_fb_info(info);
76 		var = info->var;
77 		unlock_fb_info(info);
78 
79 		ret = copy_to_user(argp, &var, sizeof(var)) ? -EFAULT : 0;
80 		break;
81 	case FBIOPUT_VSCREENINFO:
82 		if (copy_from_user(&var, argp, sizeof(var)))
83 			return -EFAULT;
84 		/* only for kernel-internal use */
85 		var.activate &= ~FB_ACTIVATE_KD_TEXT;
86 		console_lock();
87 		lock_fb_info(info);
88 		ret = fbcon_modechange_possible(info, &var);
89 		if (!ret)
90 			ret = fb_set_var(info, &var);
91 		if (!ret)
92 			fbcon_update_vcs(info, var.activate & FB_ACTIVATE_ALL);
93 		unlock_fb_info(info);
94 		console_unlock();
95 		if (!ret && copy_to_user(argp, &var, sizeof(var)))
96 			ret = -EFAULT;
97 		break;
98 	case FBIOGET_FSCREENINFO:
99 		lock_fb_info(info);
100 		memcpy(&fix, &info->fix, sizeof(fix));
101 		if (info->flags & FBINFO_HIDE_SMEM_START)
102 			fix.smem_start = 0;
103 		unlock_fb_info(info);
104 
105 		ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0;
106 		break;
107 	case FBIOPUTCMAP:
108 		if (copy_from_user(&cmap, argp, sizeof(cmap)))
109 			return -EFAULT;
110 		ret = fb_set_user_cmap(&cmap, info);
111 		break;
112 	case FBIOGETCMAP:
113 		if (copy_from_user(&cmap, argp, sizeof(cmap)))
114 			return -EFAULT;
115 		lock_fb_info(info);
116 		cmap_from = info->cmap;
117 		unlock_fb_info(info);
118 		ret = fb_cmap_to_user(&cmap_from, &cmap);
119 		break;
120 	case FBIOPAN_DISPLAY:
121 		if (copy_from_user(&var, argp, sizeof(var)))
122 			return -EFAULT;
123 		console_lock();
124 		lock_fb_info(info);
125 		ret = fb_pan_display(info, &var);
126 		unlock_fb_info(info);
127 		console_unlock();
128 		if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
129 			return -EFAULT;
130 		break;
131 	case FBIO_CURSOR:
132 		ret = -EINVAL;
133 		break;
134 	case FBIOGET_CON2FBMAP:
135 		ret = fbcon_get_con2fb_map_ioctl(argp);
136 		break;
137 	case FBIOPUT_CON2FBMAP:
138 		ret = fbcon_set_con2fb_map_ioctl(argp);
139 		break;
140 	case FBIOBLANK:
141 		if (arg > FB_BLANK_POWERDOWN)
142 			return -EINVAL;
143 		console_lock();
144 		lock_fb_info(info);
145 		ret = fb_blank(info, arg);
146 		/* might again call into fb_blank */
147 		fbcon_fb_blanked(info, arg);
148 		unlock_fb_info(info);
149 		console_unlock();
150 		break;
151 	default:
152 		lock_fb_info(info);
153 		fb = info->fbops;
154 		if (fb->fb_ioctl)
155 			ret = fb->fb_ioctl(info, cmd, arg);
156 		else
157 			ret = -ENOTTY;
158 		unlock_fb_info(info);
159 	}
160 	return ret;
161 }
162 
fb_ioctl(struct file * file,unsigned int cmd,unsigned long arg)163 static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
164 {
165 	struct fb_info *info = file_fb_info(file);
166 
167 	if (!info)
168 		return -ENODEV;
169 	return do_fb_ioctl(info, cmd, arg);
170 }
171 
172 #ifdef CONFIG_COMPAT
173 struct fb_fix_screeninfo32 {
174 	char			id[16];
175 	compat_caddr_t		smem_start;
176 	u32			smem_len;
177 	u32			type;
178 	u32			type_aux;
179 	u32			visual;
180 	u16			xpanstep;
181 	u16			ypanstep;
182 	u16			ywrapstep;
183 	u32			line_length;
184 	compat_caddr_t		mmio_start;
185 	u32			mmio_len;
186 	u32			accel;
187 	u16			reserved[3];
188 };
189 
190 struct fb_cmap32 {
191 	u32			start;
192 	u32			len;
193 	compat_caddr_t	red;
194 	compat_caddr_t	green;
195 	compat_caddr_t	blue;
196 	compat_caddr_t	transp;
197 };
198 
fb_getput_cmap(struct fb_info * info,unsigned int cmd,unsigned long arg)199 static int fb_getput_cmap(struct fb_info *info, unsigned int cmd,
200 			  unsigned long arg)
201 {
202 	struct fb_cmap32 cmap32;
203 	struct fb_cmap cmap_from;
204 	struct fb_cmap_user cmap;
205 
206 	if (copy_from_user(&cmap32, compat_ptr(arg), sizeof(cmap32)))
207 		return -EFAULT;
208 
209 	cmap = (struct fb_cmap_user) {
210 		.start	= cmap32.start,
211 		.len	= cmap32.len,
212 		.red	= compat_ptr(cmap32.red),
213 		.green	= compat_ptr(cmap32.green),
214 		.blue	= compat_ptr(cmap32.blue),
215 		.transp	= compat_ptr(cmap32.transp),
216 	};
217 
218 	if (cmd == FBIOPUTCMAP)
219 		return fb_set_user_cmap(&cmap, info);
220 
221 	lock_fb_info(info);
222 	cmap_from = info->cmap;
223 	unlock_fb_info(info);
224 
225 	return fb_cmap_to_user(&cmap_from, &cmap);
226 }
227 
do_fscreeninfo_to_user(struct fb_fix_screeninfo * fix,struct fb_fix_screeninfo32 __user * fix32)228 static int do_fscreeninfo_to_user(struct fb_fix_screeninfo *fix,
229 				  struct fb_fix_screeninfo32 __user *fix32)
230 {
231 	__u32 data;
232 	int err;
233 
234 	err = copy_to_user(&fix32->id, &fix->id, sizeof(fix32->id));
235 
236 	data = (__u32) (unsigned long) fix->smem_start;
237 	err |= put_user(data, &fix32->smem_start);
238 
239 	err |= put_user(fix->smem_len, &fix32->smem_len);
240 	err |= put_user(fix->type, &fix32->type);
241 	err |= put_user(fix->type_aux, &fix32->type_aux);
242 	err |= put_user(fix->visual, &fix32->visual);
243 	err |= put_user(fix->xpanstep, &fix32->xpanstep);
244 	err |= put_user(fix->ypanstep, &fix32->ypanstep);
245 	err |= put_user(fix->ywrapstep, &fix32->ywrapstep);
246 	err |= put_user(fix->line_length, &fix32->line_length);
247 
248 	data = (__u32) (unsigned long) fix->mmio_start;
249 	err |= put_user(data, &fix32->mmio_start);
250 
251 	err |= put_user(fix->mmio_len, &fix32->mmio_len);
252 	err |= put_user(fix->accel, &fix32->accel);
253 	err |= copy_to_user(fix32->reserved, fix->reserved,
254 			    sizeof(fix->reserved));
255 
256 	if (err)
257 		return -EFAULT;
258 	return 0;
259 }
260 
fb_get_fscreeninfo(struct fb_info * info,unsigned int cmd,unsigned long arg)261 static int fb_get_fscreeninfo(struct fb_info *info, unsigned int cmd,
262 			      unsigned long arg)
263 {
264 	struct fb_fix_screeninfo fix;
265 
266 	lock_fb_info(info);
267 	fix = info->fix;
268 	if (info->flags & FBINFO_HIDE_SMEM_START)
269 		fix.smem_start = 0;
270 	unlock_fb_info(info);
271 	return do_fscreeninfo_to_user(&fix, compat_ptr(arg));
272 }
273 
fb_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)274 static long fb_compat_ioctl(struct file *file, unsigned int cmd,
275 			    unsigned long arg)
276 {
277 	struct fb_info *info = file_fb_info(file);
278 	const struct fb_ops *fb;
279 	long ret = -ENOIOCTLCMD;
280 
281 	if (!info)
282 		return -ENODEV;
283 	fb = info->fbops;
284 	switch (cmd) {
285 	case FBIOGET_VSCREENINFO:
286 	case FBIOPUT_VSCREENINFO:
287 	case FBIOPAN_DISPLAY:
288 	case FBIOGET_CON2FBMAP:
289 	case FBIOPUT_CON2FBMAP:
290 		arg = (unsigned long) compat_ptr(arg);
291 		fallthrough;
292 	case FBIOBLANK:
293 		ret = do_fb_ioctl(info, cmd, arg);
294 		break;
295 
296 	case FBIOGET_FSCREENINFO:
297 		ret = fb_get_fscreeninfo(info, cmd, arg);
298 		break;
299 
300 	case FBIOGETCMAP:
301 	case FBIOPUTCMAP:
302 		ret = fb_getput_cmap(info, cmd, arg);
303 		break;
304 
305 	default:
306 		if (fb->fb_compat_ioctl)
307 			ret = fb->fb_compat_ioctl(info, cmd, arg);
308 		break;
309 	}
310 	return ret;
311 }
312 #endif
313 
fb_mmap(struct file * file,struct vm_area_struct * vma)314 static int fb_mmap(struct file *file, struct vm_area_struct *vma)
315 {
316 	struct fb_info *info = file_fb_info(file);
317 	int res;
318 
319 	if (!info)
320 		return -ENODEV;
321 
322 	if (fb_WARN_ON_ONCE(info, !info->fbops->fb_mmap))
323 		return -ENODEV;
324 
325 	mutex_lock(&info->mm_lock);
326 	res = info->fbops->fb_mmap(info, vma);
327 	mutex_unlock(&info->mm_lock);
328 
329 	return res;
330 }
331 
fb_open(struct inode * inode,struct file * file)332 static int fb_open(struct inode *inode, struct file *file)
333 __acquires(&info->lock)
334 __releases(&info->lock)
335 {
336 	int fbidx = iminor(inode);
337 	struct fb_info *info;
338 	int res = 0;
339 
340 	info = get_fb_info(fbidx);
341 	if (!info) {
342 		request_module("fb%d", fbidx);
343 		info = get_fb_info(fbidx);
344 		if (!info)
345 			return -ENODEV;
346 	}
347 	if (IS_ERR(info))
348 		return PTR_ERR(info);
349 
350 	lock_fb_info(info);
351 	if (!try_module_get(info->fbops->owner)) {
352 		res = -ENODEV;
353 		goto out;
354 	}
355 	file->private_data = info;
356 	if (info->fbops->fb_open) {
357 		res = info->fbops->fb_open(info, 1);
358 		if (res)
359 			module_put(info->fbops->owner);
360 	}
361 #ifdef CONFIG_FB_DEFERRED_IO
362 	if (info->fbdefio)
363 		fb_deferred_io_open(info, inode, file);
364 #endif
365 out:
366 	unlock_fb_info(info);
367 	if (res)
368 		put_fb_info(info);
369 	return res;
370 }
371 
fb_release(struct inode * inode,struct file * file)372 static int fb_release(struct inode *inode, struct file *file)
373 __acquires(&info->lock)
374 __releases(&info->lock)
375 {
376 	struct fb_info * const info = file->private_data;
377 
378 	lock_fb_info(info);
379 #if IS_ENABLED(CONFIG_FB_DEFERRED_IO)
380 	if (info->fbdefio)
381 		fb_deferred_io_release(info);
382 #endif
383 	if (info->fbops->fb_release)
384 		info->fbops->fb_release(info, 1);
385 	module_put(info->fbops->owner);
386 	unlock_fb_info(info);
387 	put_fb_info(info);
388 	return 0;
389 }
390 
391 #if defined(CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA) && !defined(CONFIG_MMU)
get_fb_unmapped_area(struct file * filp,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)392 static unsigned long get_fb_unmapped_area(struct file *filp,
393 				   unsigned long addr, unsigned long len,
394 				   unsigned long pgoff, unsigned long flags)
395 {
396 	struct fb_info * const info = filp->private_data;
397 	unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
398 
399 	if (pgoff > fb_size || len > fb_size - pgoff)
400 		return -EINVAL;
401 
402 	return (unsigned long)info->screen_base + pgoff;
403 }
404 #endif
405 
406 static const struct file_operations fb_fops = {
407 	.owner = THIS_MODULE,
408 	.read = fb_read,
409 	.write = fb_write,
410 	.unlocked_ioctl = fb_ioctl,
411 #ifdef CONFIG_COMPAT
412 	.compat_ioctl = fb_compat_ioctl,
413 #endif
414 	.mmap = fb_mmap,
415 	.open = fb_open,
416 	.release = fb_release,
417 #if defined(HAVE_ARCH_FB_UNMAPPED_AREA) || \
418 	(defined(CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA) && \
419 	 !defined(CONFIG_MMU))
420 	.get_unmapped_area = get_fb_unmapped_area,
421 #endif
422 #ifdef CONFIG_FB_DEFERRED_IO
423 	.fsync = fb_deferred_io_fsync,
424 #endif
425 	.llseek = default_llseek,
426 };
427 
fb_register_chrdev(void)428 int fb_register_chrdev(void)
429 {
430 	int ret;
431 
432 	ret = register_chrdev(FB_MAJOR, "fb", &fb_fops);
433 	if (ret) {
434 		pr_err("Unable to get major %d for fb devs\n", FB_MAJOR);
435 		return ret;
436 	}
437 
438 	return ret;
439 }
440 
fb_unregister_chrdev(void)441 void fb_unregister_chrdev(void)
442 {
443 	unregister_chrdev(FB_MAJOR, "fb");
444 }
445