xref: /openbmc/linux/arch/s390/kernel/compat_linux.c (revision e7065e20)
1 /*
2  *  arch/s390x/kernel/linux32.c
3  *
4  *  S390 version
5  *    Copyright (C) 2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
7  *               Gerhard Tonn (ton@de.ibm.com)
8  *               Thomas Spatzier (tspat@de.ibm.com)
9  *
10  *  Conversion between 31bit and 64bit native syscalls.
11  *
12  * Heavily inspired by the 32-bit Sparc compat code which is
13  * Copyright (C) 1997,1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
14  * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
15  *
16  */
17 
18 
19 #include <linux/kernel.h>
20 #include <linux/sched.h>
21 #include <linux/fs.h>
22 #include <linux/mm.h>
23 #include <linux/file.h>
24 #include <linux/signal.h>
25 #include <linux/resource.h>
26 #include <linux/times.h>
27 #include <linux/smp.h>
28 #include <linux/sem.h>
29 #include <linux/msg.h>
30 #include <linux/shm.h>
31 #include <linux/uio.h>
32 #include <linux/quota.h>
33 #include <linux/module.h>
34 #include <linux/poll.h>
35 #include <linux/personality.h>
36 #include <linux/stat.h>
37 #include <linux/filter.h>
38 #include <linux/highmem.h>
39 #include <linux/highuid.h>
40 #include <linux/mman.h>
41 #include <linux/ipv6.h>
42 #include <linux/in.h>
43 #include <linux/icmpv6.h>
44 #include <linux/syscalls.h>
45 #include <linux/sysctl.h>
46 #include <linux/binfmts.h>
47 #include <linux/capability.h>
48 #include <linux/compat.h>
49 #include <linux/vfs.h>
50 #include <linux/ptrace.h>
51 #include <linux/fadvise.h>
52 #include <linux/ipc.h>
53 #include <linux/slab.h>
54 
55 #include <asm/types.h>
56 #include <asm/uaccess.h>
57 
58 #include <net/scm.h>
59 #include <net/sock.h>
60 
61 #include "compat_linux.h"
62 
63 u32 psw32_user_bits = PSW32_MASK_DAT | PSW32_MASK_IO | PSW32_MASK_EXT |
64 		      PSW32_DEFAULT_KEY | PSW32_MASK_BASE | PSW32_MASK_MCHECK |
65 		      PSW32_MASK_PSTATE | PSW32_ASC_HOME;
66 
67 /* For this source file, we want overflow handling. */
68 
69 #undef high2lowuid
70 #undef high2lowgid
71 #undef low2highuid
72 #undef low2highgid
73 #undef SET_UID16
74 #undef SET_GID16
75 #undef NEW_TO_OLD_UID
76 #undef NEW_TO_OLD_GID
77 #undef SET_OLDSTAT_UID
78 #undef SET_OLDSTAT_GID
79 #undef SET_STAT_UID
80 #undef SET_STAT_GID
81 
82 #define high2lowuid(uid) ((uid) > 65535) ? (u16)overflowuid : (u16)(uid)
83 #define high2lowgid(gid) ((gid) > 65535) ? (u16)overflowgid : (u16)(gid)
84 #define low2highuid(uid) ((uid) == (u16)-1) ? (uid_t)-1 : (uid_t)(uid)
85 #define low2highgid(gid) ((gid) == (u16)-1) ? (gid_t)-1 : (gid_t)(gid)
86 #define SET_UID16(var, uid)	var = high2lowuid(uid)
87 #define SET_GID16(var, gid)	var = high2lowgid(gid)
88 #define NEW_TO_OLD_UID(uid)	high2lowuid(uid)
89 #define NEW_TO_OLD_GID(gid)	high2lowgid(gid)
90 #define SET_OLDSTAT_UID(stat, uid)	(stat).st_uid = high2lowuid(uid)
91 #define SET_OLDSTAT_GID(stat, gid)	(stat).st_gid = high2lowgid(gid)
92 #define SET_STAT_UID(stat, uid)		(stat).st_uid = high2lowuid(uid)
93 #define SET_STAT_GID(stat, gid)		(stat).st_gid = high2lowgid(gid)
94 
95 asmlinkage long sys32_chown16(const char __user * filename, u16 user, u16 group)
96 {
97 	return sys_chown(filename, low2highuid(user), low2highgid(group));
98 }
99 
100 asmlinkage long sys32_lchown16(const char __user * filename, u16 user, u16 group)
101 {
102 	return sys_lchown(filename, low2highuid(user), low2highgid(group));
103 }
104 
105 asmlinkage long sys32_fchown16(unsigned int fd, u16 user, u16 group)
106 {
107 	return sys_fchown(fd, low2highuid(user), low2highgid(group));
108 }
109 
110 asmlinkage long sys32_setregid16(u16 rgid, u16 egid)
111 {
112 	return sys_setregid(low2highgid(rgid), low2highgid(egid));
113 }
114 
115 asmlinkage long sys32_setgid16(u16 gid)
116 {
117 	return sys_setgid((gid_t)gid);
118 }
119 
120 asmlinkage long sys32_setreuid16(u16 ruid, u16 euid)
121 {
122 	return sys_setreuid(low2highuid(ruid), low2highuid(euid));
123 }
124 
125 asmlinkage long sys32_setuid16(u16 uid)
126 {
127 	return sys_setuid((uid_t)uid);
128 }
129 
130 asmlinkage long sys32_setresuid16(u16 ruid, u16 euid, u16 suid)
131 {
132 	return sys_setresuid(low2highuid(ruid), low2highuid(euid),
133 		low2highuid(suid));
134 }
135 
136 asmlinkage long sys32_getresuid16(u16 __user *ruid, u16 __user *euid, u16 __user *suid)
137 {
138 	int retval;
139 
140 	if (!(retval = put_user(high2lowuid(current->cred->uid), ruid)) &&
141 	    !(retval = put_user(high2lowuid(current->cred->euid), euid)))
142 		retval = put_user(high2lowuid(current->cred->suid), suid);
143 
144 	return retval;
145 }
146 
147 asmlinkage long sys32_setresgid16(u16 rgid, u16 egid, u16 sgid)
148 {
149 	return sys_setresgid(low2highgid(rgid), low2highgid(egid),
150 		low2highgid(sgid));
151 }
152 
153 asmlinkage long sys32_getresgid16(u16 __user *rgid, u16 __user *egid, u16 __user *sgid)
154 {
155 	int retval;
156 
157 	if (!(retval = put_user(high2lowgid(current->cred->gid), rgid)) &&
158 	    !(retval = put_user(high2lowgid(current->cred->egid), egid)))
159 		retval = put_user(high2lowgid(current->cred->sgid), sgid);
160 
161 	return retval;
162 }
163 
164 asmlinkage long sys32_setfsuid16(u16 uid)
165 {
166 	return sys_setfsuid((uid_t)uid);
167 }
168 
169 asmlinkage long sys32_setfsgid16(u16 gid)
170 {
171 	return sys_setfsgid((gid_t)gid);
172 }
173 
174 static int groups16_to_user(u16 __user *grouplist, struct group_info *group_info)
175 {
176 	int i;
177 	u16 group;
178 
179 	for (i = 0; i < group_info->ngroups; i++) {
180 		group = (u16)GROUP_AT(group_info, i);
181 		if (put_user(group, grouplist+i))
182 			return -EFAULT;
183 	}
184 
185 	return 0;
186 }
187 
188 static int groups16_from_user(struct group_info *group_info, u16 __user *grouplist)
189 {
190 	int i;
191 	u16 group;
192 
193 	for (i = 0; i < group_info->ngroups; i++) {
194 		if (get_user(group, grouplist+i))
195 			return  -EFAULT;
196 		GROUP_AT(group_info, i) = (gid_t)group;
197 	}
198 
199 	return 0;
200 }
201 
202 asmlinkage long sys32_getgroups16(int gidsetsize, u16 __user *grouplist)
203 {
204 	int i;
205 
206 	if (gidsetsize < 0)
207 		return -EINVAL;
208 
209 	get_group_info(current->cred->group_info);
210 	i = current->cred->group_info->ngroups;
211 	if (gidsetsize) {
212 		if (i > gidsetsize) {
213 			i = -EINVAL;
214 			goto out;
215 		}
216 		if (groups16_to_user(grouplist, current->cred->group_info)) {
217 			i = -EFAULT;
218 			goto out;
219 		}
220 	}
221 out:
222 	put_group_info(current->cred->group_info);
223 	return i;
224 }
225 
226 asmlinkage long sys32_setgroups16(int gidsetsize, u16 __user *grouplist)
227 {
228 	struct group_info *group_info;
229 	int retval;
230 
231 	if (!capable(CAP_SETGID))
232 		return -EPERM;
233 	if ((unsigned)gidsetsize > NGROUPS_MAX)
234 		return -EINVAL;
235 
236 	group_info = groups_alloc(gidsetsize);
237 	if (!group_info)
238 		return -ENOMEM;
239 	retval = groups16_from_user(group_info, grouplist);
240 	if (retval) {
241 		put_group_info(group_info);
242 		return retval;
243 	}
244 
245 	retval = set_current_groups(group_info);
246 	put_group_info(group_info);
247 
248 	return retval;
249 }
250 
251 asmlinkage long sys32_getuid16(void)
252 {
253 	return high2lowuid(current->cred->uid);
254 }
255 
256 asmlinkage long sys32_geteuid16(void)
257 {
258 	return high2lowuid(current->cred->euid);
259 }
260 
261 asmlinkage long sys32_getgid16(void)
262 {
263 	return high2lowgid(current->cred->gid);
264 }
265 
266 asmlinkage long sys32_getegid16(void)
267 {
268 	return high2lowgid(current->cred->egid);
269 }
270 
271 /*
272  * sys32_ipc() is the de-multiplexer for the SysV IPC calls in 32bit emulation.
273  *
274  * This is really horribly ugly.
275  */
276 #ifdef CONFIG_SYSVIPC
277 asmlinkage long sys32_ipc(u32 call, int first, int second, int third, u32 ptr)
278 {
279 	if (call >> 16)		/* hack for backward compatibility */
280 		return -EINVAL;
281 	switch (call) {
282 	case SEMTIMEDOP:
283 		return compat_sys_semtimedop(first, compat_ptr(ptr),
284 					     second, compat_ptr(third));
285 	case SEMOP:
286 		/* struct sembuf is the same on 32 and 64bit :)) */
287 		return sys_semtimedop(first, compat_ptr(ptr),
288 				      second, NULL);
289 	case SEMGET:
290 		return sys_semget(first, second, third);
291 	case SEMCTL:
292 		return compat_sys_semctl(first, second, third,
293 					 compat_ptr(ptr));
294 	case MSGSND:
295 		return compat_sys_msgsnd(first, second, third,
296 					 compat_ptr(ptr));
297 	case MSGRCV:
298 		return compat_sys_msgrcv(first, second, 0, third,
299 					 0, compat_ptr(ptr));
300 	case MSGGET:
301 		return sys_msgget((key_t) first, second);
302 	case MSGCTL:
303 		return compat_sys_msgctl(first, second, compat_ptr(ptr));
304 	case SHMAT:
305 		return compat_sys_shmat(first, second, third,
306 					0, compat_ptr(ptr));
307 	case SHMDT:
308 		return sys_shmdt(compat_ptr(ptr));
309 	case SHMGET:
310 		return sys_shmget(first, (unsigned)second, third);
311 	case SHMCTL:
312 		return compat_sys_shmctl(first, second, compat_ptr(ptr));
313 	}
314 
315 	return -ENOSYS;
316 }
317 #endif
318 
319 asmlinkage long sys32_truncate64(const char __user * path, unsigned long high, unsigned long low)
320 {
321 	if ((int)high < 0)
322 		return -EINVAL;
323 	else
324 		return sys_truncate(path, (high << 32) | low);
325 }
326 
327 asmlinkage long sys32_ftruncate64(unsigned int fd, unsigned long high, unsigned long low)
328 {
329 	if ((int)high < 0)
330 		return -EINVAL;
331 	else
332 		return sys_ftruncate(fd, (high << 32) | low);
333 }
334 
335 asmlinkage long sys32_sched_rr_get_interval(compat_pid_t pid,
336 				struct compat_timespec __user *interval)
337 {
338 	struct timespec t;
339 	int ret;
340 	mm_segment_t old_fs = get_fs ();
341 
342 	set_fs (KERNEL_DS);
343 	ret = sys_sched_rr_get_interval(pid,
344 					(struct timespec __force __user *) &t);
345 	set_fs (old_fs);
346 	if (put_compat_timespec(&t, interval))
347 		return -EFAULT;
348 	return ret;
349 }
350 
351 asmlinkage long sys32_rt_sigprocmask(int how, compat_sigset_t __user *set,
352 			compat_sigset_t __user *oset, size_t sigsetsize)
353 {
354 	sigset_t s;
355 	compat_sigset_t s32;
356 	int ret;
357 	mm_segment_t old_fs = get_fs();
358 
359 	if (set) {
360 		if (copy_from_user (&s32, set, sizeof(compat_sigset_t)))
361 			return -EFAULT;
362 		s.sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
363 	}
364 	set_fs (KERNEL_DS);
365 	ret = sys_rt_sigprocmask(how,
366 				 set ? (sigset_t __force __user *) &s : NULL,
367 				 oset ? (sigset_t __force __user *) &s : NULL,
368 				 sigsetsize);
369 	set_fs (old_fs);
370 	if (ret) return ret;
371 	if (oset) {
372 		s32.sig[1] = (s.sig[0] >> 32);
373 		s32.sig[0] = s.sig[0];
374 		if (copy_to_user (oset, &s32, sizeof(compat_sigset_t)))
375 			return -EFAULT;
376 	}
377 	return 0;
378 }
379 
380 asmlinkage long sys32_rt_sigpending(compat_sigset_t __user *set,
381 				size_t sigsetsize)
382 {
383 	sigset_t s;
384 	compat_sigset_t s32;
385 	int ret;
386 	mm_segment_t old_fs = get_fs();
387 
388 	set_fs (KERNEL_DS);
389 	ret = sys_rt_sigpending((sigset_t __force __user *) &s, sigsetsize);
390 	set_fs (old_fs);
391 	if (!ret) {
392 		s32.sig[1] = (s.sig[0] >> 32);
393 		s32.sig[0] = s.sig[0];
394 		if (copy_to_user (set, &s32, sizeof(compat_sigset_t)))
395 			return -EFAULT;
396 	}
397 	return ret;
398 }
399 
400 asmlinkage long
401 sys32_rt_sigqueueinfo(int pid, int sig, compat_siginfo_t __user *uinfo)
402 {
403 	siginfo_t info;
404 	int ret;
405 	mm_segment_t old_fs = get_fs();
406 
407 	if (copy_siginfo_from_user32(&info, uinfo))
408 		return -EFAULT;
409 	set_fs (KERNEL_DS);
410 	ret = sys_rt_sigqueueinfo(pid, sig, (siginfo_t __force __user *) &info);
411 	set_fs (old_fs);
412 	return ret;
413 }
414 
415 /*
416  * sys32_execve() executes a new program after the asm stub has set
417  * things up for us.  This should basically do what I want it to.
418  */
419 asmlinkage long sys32_execve(const char __user *name, compat_uptr_t __user *argv,
420 			     compat_uptr_t __user *envp)
421 {
422 	struct pt_regs *regs = task_pt_regs(current);
423 	char *filename;
424 	long rc;
425 
426 	filename = getname(name);
427 	rc = PTR_ERR(filename);
428 	if (IS_ERR(filename))
429 		return rc;
430 	rc = compat_do_execve(filename, argv, envp, regs);
431 	if (rc)
432 		goto out;
433 	current->thread.fp_regs.fpc=0;
434 	asm volatile("sfpc %0,0" : : "d" (0));
435 	rc = regs->gprs[2];
436 out:
437 	putname(filename);
438 	return rc;
439 }
440 
441 asmlinkage long sys32_pread64(unsigned int fd, char __user *ubuf,
442 				size_t count, u32 poshi, u32 poslo)
443 {
444 	if ((compat_ssize_t) count < 0)
445 		return -EINVAL;
446 	return sys_pread64(fd, ubuf, count, ((loff_t)AA(poshi) << 32) | AA(poslo));
447 }
448 
449 asmlinkage long sys32_pwrite64(unsigned int fd, const char __user *ubuf,
450 				size_t count, u32 poshi, u32 poslo)
451 {
452 	if ((compat_ssize_t) count < 0)
453 		return -EINVAL;
454 	return sys_pwrite64(fd, ubuf, count, ((loff_t)AA(poshi) << 32) | AA(poslo));
455 }
456 
457 asmlinkage compat_ssize_t sys32_readahead(int fd, u32 offhi, u32 offlo, s32 count)
458 {
459 	return sys_readahead(fd, ((loff_t)AA(offhi) << 32) | AA(offlo), count);
460 }
461 
462 asmlinkage long sys32_sendfile(int out_fd, int in_fd, compat_off_t __user *offset, size_t count)
463 {
464 	mm_segment_t old_fs = get_fs();
465 	int ret;
466 	off_t of;
467 
468 	if (offset && get_user(of, offset))
469 		return -EFAULT;
470 
471 	set_fs(KERNEL_DS);
472 	ret = sys_sendfile(out_fd, in_fd,
473 			   offset ? (off_t __force __user *) &of : NULL, count);
474 	set_fs(old_fs);
475 
476 	if (offset && put_user(of, offset))
477 		return -EFAULT;
478 
479 	return ret;
480 }
481 
482 asmlinkage long sys32_sendfile64(int out_fd, int in_fd,
483 				compat_loff_t __user *offset, s32 count)
484 {
485 	mm_segment_t old_fs = get_fs();
486 	int ret;
487 	loff_t lof;
488 
489 	if (offset && get_user(lof, offset))
490 		return -EFAULT;
491 
492 	set_fs(KERNEL_DS);
493 	ret = sys_sendfile64(out_fd, in_fd,
494 			     offset ? (loff_t __force __user *) &lof : NULL,
495 			     count);
496 	set_fs(old_fs);
497 
498 	if (offset && put_user(lof, offset))
499 		return -EFAULT;
500 
501 	return ret;
502 }
503 
504 struct stat64_emu31 {
505 	unsigned long long  st_dev;
506 	unsigned int    __pad1;
507 #define STAT64_HAS_BROKEN_ST_INO        1
508 	u32             __st_ino;
509 	unsigned int    st_mode;
510 	unsigned int    st_nlink;
511 	u32             st_uid;
512 	u32             st_gid;
513 	unsigned long long  st_rdev;
514 	unsigned int    __pad3;
515 	long            st_size;
516 	u32             st_blksize;
517 	unsigned char   __pad4[4];
518 	u32             __pad5;     /* future possible st_blocks high bits */
519 	u32             st_blocks;  /* Number 512-byte blocks allocated. */
520 	u32             st_atime;
521 	u32             __pad6;
522 	u32             st_mtime;
523 	u32             __pad7;
524 	u32             st_ctime;
525 	u32             __pad8;     /* will be high 32 bits of ctime someday */
526 	unsigned long   st_ino;
527 };
528 
529 static int cp_stat64(struct stat64_emu31 __user *ubuf, struct kstat *stat)
530 {
531 	struct stat64_emu31 tmp;
532 
533 	memset(&tmp, 0, sizeof(tmp));
534 
535 	tmp.st_dev = huge_encode_dev(stat->dev);
536 	tmp.st_ino = stat->ino;
537 	tmp.__st_ino = (u32)stat->ino;
538 	tmp.st_mode = stat->mode;
539 	tmp.st_nlink = (unsigned int)stat->nlink;
540 	tmp.st_uid = stat->uid;
541 	tmp.st_gid = stat->gid;
542 	tmp.st_rdev = huge_encode_dev(stat->rdev);
543 	tmp.st_size = stat->size;
544 	tmp.st_blksize = (u32)stat->blksize;
545 	tmp.st_blocks = (u32)stat->blocks;
546 	tmp.st_atime = (u32)stat->atime.tv_sec;
547 	tmp.st_mtime = (u32)stat->mtime.tv_sec;
548 	tmp.st_ctime = (u32)stat->ctime.tv_sec;
549 
550 	return copy_to_user(ubuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
551 }
552 
553 asmlinkage long sys32_stat64(const char __user * filename, struct stat64_emu31 __user * statbuf)
554 {
555 	struct kstat stat;
556 	int ret = vfs_stat(filename, &stat);
557 	if (!ret)
558 		ret = cp_stat64(statbuf, &stat);
559 	return ret;
560 }
561 
562 asmlinkage long sys32_lstat64(const char __user * filename, struct stat64_emu31 __user * statbuf)
563 {
564 	struct kstat stat;
565 	int ret = vfs_lstat(filename, &stat);
566 	if (!ret)
567 		ret = cp_stat64(statbuf, &stat);
568 	return ret;
569 }
570 
571 asmlinkage long sys32_fstat64(unsigned long fd, struct stat64_emu31 __user * statbuf)
572 {
573 	struct kstat stat;
574 	int ret = vfs_fstat(fd, &stat);
575 	if (!ret)
576 		ret = cp_stat64(statbuf, &stat);
577 	return ret;
578 }
579 
580 asmlinkage long sys32_fstatat64(unsigned int dfd, const char __user *filename,
581 				struct stat64_emu31 __user* statbuf, int flag)
582 {
583 	struct kstat stat;
584 	int error;
585 
586 	error = vfs_fstatat(dfd, filename, &stat, flag);
587 	if (error)
588 		return error;
589 	return cp_stat64(statbuf, &stat);
590 }
591 
592 /*
593  * Linux/i386 didn't use to be able to handle more than
594  * 4 system call parameters, so these system calls used a memory
595  * block for parameter passing..
596  */
597 
598 struct mmap_arg_struct_emu31 {
599 	compat_ulong_t addr;
600 	compat_ulong_t len;
601 	compat_ulong_t prot;
602 	compat_ulong_t flags;
603 	compat_ulong_t fd;
604 	compat_ulong_t offset;
605 };
606 
607 asmlinkage unsigned long old32_mmap(struct mmap_arg_struct_emu31 __user *arg)
608 {
609 	struct mmap_arg_struct_emu31 a;
610 
611 	if (copy_from_user(&a, arg, sizeof(a)))
612 		return -EFAULT;
613 	if (a.offset & ~PAGE_MASK)
614 		return -EINVAL;
615 	a.addr = (unsigned long) compat_ptr(a.addr);
616 	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
617 			      a.offset >> PAGE_SHIFT);
618 }
619 
620 asmlinkage long sys32_mmap2(struct mmap_arg_struct_emu31 __user *arg)
621 {
622 	struct mmap_arg_struct_emu31 a;
623 
624 	if (copy_from_user(&a, arg, sizeof(a)))
625 		return -EFAULT;
626 	a.addr = (unsigned long) compat_ptr(a.addr);
627 	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, a.offset);
628 }
629 
630 asmlinkage long sys32_read(unsigned int fd, char __user * buf, size_t count)
631 {
632 	if ((compat_ssize_t) count < 0)
633 		return -EINVAL;
634 
635 	return sys_read(fd, buf, count);
636 }
637 
638 asmlinkage long sys32_write(unsigned int fd, const char __user * buf, size_t count)
639 {
640 	if ((compat_ssize_t) count < 0)
641 		return -EINVAL;
642 
643 	return sys_write(fd, buf, count);
644 }
645 
646 /*
647  * 31 bit emulation wrapper functions for sys_fadvise64/fadvise64_64.
648  * These need to rewrite the advise values for POSIX_FADV_{DONTNEED,NOREUSE}
649  * because the 31 bit values differ from the 64 bit values.
650  */
651 
652 asmlinkage long
653 sys32_fadvise64(int fd, loff_t offset, size_t len, int advise)
654 {
655 	if (advise == 4)
656 		advise = POSIX_FADV_DONTNEED;
657 	else if (advise == 5)
658 		advise = POSIX_FADV_NOREUSE;
659 	return sys_fadvise64(fd, offset, len, advise);
660 }
661 
662 struct fadvise64_64_args {
663 	int fd;
664 	long long offset;
665 	long long len;
666 	int advice;
667 };
668 
669 asmlinkage long
670 sys32_fadvise64_64(struct fadvise64_64_args __user *args)
671 {
672 	struct fadvise64_64_args a;
673 
674 	if ( copy_from_user(&a, args, sizeof(a)) )
675 		return -EFAULT;
676 	if (a.advice == 4)
677 		a.advice = POSIX_FADV_DONTNEED;
678 	else if (a.advice == 5)
679 		a.advice = POSIX_FADV_NOREUSE;
680 	return sys_fadvise64_64(a.fd, a.offset, a.len, a.advice);
681 }
682