sys_sparc_64.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* linux/arch/sparc64/kernel/sys_sparc.c
  3 *
  4 * This file contains various random system calls that
  5 * have a non-standard calling sequence on the Linux/sparc
  6 * platform.
  7 */
  8
  9#include <linux/errno.h>
 10#include <linux/types.h>
 11#include <linux/sched/signal.h>
 12#include <linux/sched/mm.h>
 13#include <linux/sched/debug.h>
 14#include <linux/fs.h>
 15#include <linux/file.h>
 16#include <linux/mm.h>
 17#include <linux/sem.h>
 18#include <linux/msg.h>
 19#include <linux/shm.h>
 20#include <linux/stat.h>
 21#include <linux/mman.h>
 22#include <linux/utsname.h>
 23#include <linux/smp.h>
 24#include <linux/slab.h>
 25#include <linux/syscalls.h>
 26#include <linux/ipc.h>
 27#include <linux/personality.h>
 28#include <linux/random.h>
 29#include <linux/export.h>
 30#include <linux/context_tracking.h>
 31#include <linux/timex.h>
 32#include <linux/uaccess.h>
 33#include <linux/hugetlb.h>
 34
 35#include <asm/utrap.h>
 36#include <asm/unistd.h>
 37
 38#include "entry.h"
 39#include "kernel.h"
 40#include "systbls.h"
 41
 42/* #define DEBUG_UNIMP_SYSCALL */
 43
 44SYSCALL_DEFINE0(getpagesize)
 45{
 46	return PAGE_SIZE;
 47}
 48
 49/* Does addr --> addr+len fall within 4GB of the VA-space hole or
 50 * overflow past the end of the 64-bit address space?
 51 */
 52static inline int invalid_64bit_range(unsigned long addr, unsigned long len)
 53{
 54	unsigned long va_exclude_start, va_exclude_end;
 55
 56	va_exclude_start = VA_EXCLUDE_START;
 57	va_exclude_end   = VA_EXCLUDE_END;
 58
 59	if (unlikely(len >= va_exclude_start))
 60		return 1;
 61
 62	if (unlikely((addr + len) < addr))
 63		return 1;
 64
 65	if (unlikely((addr >= va_exclude_start && addr < va_exclude_end) ||
 66		     ((addr + len) >= va_exclude_start &&
 67		      (addr + len) < va_exclude_end)))
 68		return 1;
 69
 70	return 0;
 71}
 72
 73/* These functions differ from the default implementations in
 74 * mm/mmap.c in two ways:
 75 *
 76 * 1) For file backed MAP_SHARED mmap()'s we D-cache color align,
 77 *    for fixed such mappings we just validate what the user gave us.
 78 * 2) For 64-bit tasks we avoid mapping anything within 4GB of
 79 *    the spitfire/niagara VA-hole.
 80 */
 81
 82static inline unsigned long COLOR_ALIGN(unsigned long addr,
 83					 unsigned long pgoff)
 84{
 85	unsigned long base = (addr+SHMLBA-1)&~(SHMLBA-1);
 86	unsigned long off = (pgoff<<PAGE_SHIFT) & (SHMLBA-1);
 87
 88	return base + off;
 89}
 90
 91static unsigned long get_align_mask(struct file *filp, unsigned long flags)
 92{
 93	if (filp && is_file_hugepages(filp))
 94		return huge_page_mask_align(filp);
 95	if (filp || (flags & MAP_SHARED))
 96		return PAGE_MASK & (SHMLBA - 1);
 97
 98	return 0;
 99}
100
101unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags)
102{
103	struct mm_struct *mm = current->mm;
104	struct vm_area_struct * vma;
105	unsigned long task_size = TASK_SIZE;
106	int do_color_align;
107	struct vm_unmapped_area_info info = {};
108	bool file_hugepage = false;
109
110	if (filp && is_file_hugepages(filp))
111		file_hugepage = true;
112
113	if (flags & MAP_FIXED) {
114		/* We do not accept a shared mapping if it would violate
115		 * cache aliasing constraints.
116		 */
117		if (!file_hugepage && (flags & MAP_SHARED) &&
118		    ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
119			return -EINVAL;
120		return addr;
121	}
122
123	if (test_thread_flag(TIF_32BIT))
124		task_size = STACK_TOP32;
125	if (unlikely(len > task_size || len >= VA_EXCLUDE_START))
126		return -ENOMEM;
127
128	do_color_align = 0;
129	if ((filp || (flags & MAP_SHARED)) && !file_hugepage)
130		do_color_align = 1;
131
132	if (addr) {
133		if (do_color_align)
134			addr = COLOR_ALIGN(addr, pgoff);
135		else
136			addr = PAGE_ALIGN(addr);
137
138		vma = find_vma(mm, addr);
139		if (task_size - len >= addr &&
140		    (!vma || addr + len <= vm_start_gap(vma)))
141			return addr;
142	}
143
144	info.length = len;
145	info.low_limit = TASK_UNMAPPED_BASE;
146	info.high_limit = min(task_size, VA_EXCLUDE_START);
147	info.align_mask = get_align_mask(filp, flags);
148	if (!file_hugepage)
149		info.align_offset = pgoff << PAGE_SHIFT;
150	addr = vm_unmapped_area(&info);
151
152	if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
153		VM_BUG_ON(addr != -ENOMEM);
154		info.low_limit = VA_EXCLUDE_END;
155		info.high_limit = task_size;
156		addr = vm_unmapped_area(&info);
157	}
158
159	return addr;
160}
161
162unsigned long
163arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
164			  const unsigned long len, const unsigned long pgoff,
165			  const unsigned long flags, vm_flags_t vm_flags)
166{
167	struct vm_area_struct *vma;
168	struct mm_struct *mm = current->mm;
169	unsigned long task_size = STACK_TOP32;
170	unsigned long addr = addr0;
171	int do_color_align;
172	struct vm_unmapped_area_info info = {};
173	bool file_hugepage = false;
174
175	/* This should only ever run for 32-bit processes.  */
176	BUG_ON(!test_thread_flag(TIF_32BIT));
177
178	if (filp && is_file_hugepages(filp))
179		file_hugepage = true;
180
181	if (flags & MAP_FIXED) {
182		/* We do not accept a shared mapping if it would violate
183		 * cache aliasing constraints.
184		 */
185		if (!file_hugepage && (flags & MAP_SHARED) &&
186		    ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
187			return -EINVAL;
188		return addr;
189	}
190
191	if (unlikely(len > task_size))
192		return -ENOMEM;
193
194	do_color_align = 0;
195	if ((filp || (flags & MAP_SHARED)) && !file_hugepage)
196		do_color_align = 1;
197
198	/* requesting a specific address */
199	if (addr) {
200		if (do_color_align)
201			addr = COLOR_ALIGN(addr, pgoff);
202		else
203			addr = PAGE_ALIGN(addr);
204
205		vma = find_vma(mm, addr);
206		if (task_size - len >= addr &&
207		    (!vma || addr + len <= vm_start_gap(vma)))
208			return addr;
209	}
210
211	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
212	info.length = len;
213	info.low_limit = PAGE_SIZE;
214	info.high_limit = mm->mmap_base;
215	info.align_mask = get_align_mask(filp, flags);
216	if (!file_hugepage)
217		info.align_offset = pgoff << PAGE_SHIFT;
218	addr = vm_unmapped_area(&info);
219
220	/*
221	 * A failed mmap() very likely causes application failure,
222	 * so fall back to the bottom-up function here. This scenario
223	 * can happen with large stack limits and large mmap()
224	 * allocations.
225	 */
226	if (addr & ~PAGE_MASK) {
227		VM_BUG_ON(addr != -ENOMEM);
228		info.flags = 0;
229		info.low_limit = TASK_UNMAPPED_BASE;
230		info.high_limit = STACK_TOP32;
231		addr = vm_unmapped_area(&info);
232	}
233
234	return addr;
235}
236
237/* Try to align mapping such that we align it as much as possible. */
238unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
239{
240	unsigned long align_goal, addr = -ENOMEM;
241
242	if (flags & MAP_FIXED) {
243		/* Ok, don't mess with it. */
244		return mm_get_unmapped_area(NULL, orig_addr, len, pgoff, flags);
245	}
246	flags &= ~MAP_SHARED;
247
248	align_goal = PAGE_SIZE;
249	if (len >= (4UL * 1024 * 1024))
250		align_goal = (4UL * 1024 * 1024);
251	else if (len >= (512UL * 1024))
252		align_goal = (512UL * 1024);
253	else if (len >= (64UL * 1024))
254		align_goal = (64UL * 1024);
255
256	do {
257		addr = mm_get_unmapped_area(NULL, orig_addr,
258					    len + (align_goal - PAGE_SIZE), pgoff, flags);
259		if (!(addr & ~PAGE_MASK)) {
260			addr = (addr + (align_goal - 1UL)) & ~(align_goal - 1UL);
261			break;
262		}
263
264		if (align_goal == (4UL * 1024 * 1024))
265			align_goal = (512UL * 1024);
266		else if (align_goal == (512UL * 1024))
267			align_goal = (64UL * 1024);
268		else
269			align_goal = PAGE_SIZE;
270	} while ((addr & ~PAGE_MASK) && align_goal > PAGE_SIZE);
271
272	/* Mapping is smaller than 64K or larger areas could not
273	 * be obtained.
274	 */
275	if (addr & ~PAGE_MASK)
276		addr = mm_get_unmapped_area(NULL, orig_addr, len, pgoff, flags);
277
278	return addr;
279}
280EXPORT_SYMBOL(get_fb_unmapped_area);
281
282/* Essentially the same as PowerPC.  */
283static unsigned long mmap_rnd(void)
284{
285	unsigned long rnd = 0UL;
286
287	if (current->flags & PF_RANDOMIZE) {
288		unsigned long val = get_random_long();
289		if (test_thread_flag(TIF_32BIT))
290			rnd = (val % (1UL << (23UL-PAGE_SHIFT)));
291		else
292			rnd = (val % (1UL << (30UL-PAGE_SHIFT)));
293	}
294	return rnd << PAGE_SHIFT;
295}
296
297void arch_pick_mmap_layout(struct mm_struct *mm, const struct rlimit *rlim_stack)
298{
299	unsigned long random_factor = mmap_rnd();
300	unsigned long gap;
301
302	/*
303	 * Fall back to the standard layout if the personality
304	 * bit is set, or if the expected stack growth is unlimited:
305	 */
306	gap = rlim_stack->rlim_cur;
307	if (!test_thread_flag(TIF_32BIT) ||
308	    (current->personality & ADDR_COMPAT_LAYOUT) ||
309	    gap == RLIM_INFINITY ||
310	    sysctl_legacy_va_layout) {
311		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
312		mm_flags_clear(MMF_TOPDOWN, mm);
313	} else {
314		/* We know it's 32-bit */
315		unsigned long task_size = STACK_TOP32;
316
317		if (gap < 128 * 1024 * 1024)
318			gap = 128 * 1024 * 1024;
319		if (gap > (task_size / 6 * 5))
320			gap = (task_size / 6 * 5);
321
322		mm->mmap_base = PAGE_ALIGN(task_size - gap - random_factor);
323		mm_flags_set(MMF_TOPDOWN, mm);
324	}
325}
326
327/*
328 * sys_pipe() is the normal C calling standard for creating
329 * a pipe. It's not the way unix traditionally does this, though.
330 */
331SYSCALL_DEFINE0(sparc_pipe)
332{
333	int fd[2];
334	int error;
335
336	error = do_pipe_flags(fd, 0);
337	if (error)
338		goto out;
339	current_pt_regs()->u_regs[UREG_I1] = fd[1];
340	error = fd[0];
341out:
342	return error;
343}
344
345/*
346 * sys_ipc() is the de-multiplexer for the SysV IPC calls..
347 *
348 * This is really horribly ugly.
349 */
350
351SYSCALL_DEFINE6(sparc_ipc, unsigned int, call, int, first, unsigned long, second,
352		unsigned long, third, void __user *, ptr, long, fifth)
353{
354	long err;
355
356	if (!IS_ENABLED(CONFIG_SYSVIPC))
357		return -ENOSYS;
358
359	/* No need for backward compatibility. We can start fresh... */
360	if (call <= SEMTIMEDOP) {
361		switch (call) {
362		case SEMOP:
363			err = ksys_semtimedop(first, ptr,
364					      (unsigned int)second, NULL);
365			goto out;
366		case SEMTIMEDOP:
367			err = ksys_semtimedop(first, ptr, (unsigned int)second,
368				(const struct __kernel_timespec __user *)
369					      (unsigned long) fifth);
370			goto out;
371		case SEMGET:
372			err = ksys_semget(first, (int)second, (int)third);
373			goto out;
374		case SEMCTL: {
375			err = ksys_old_semctl(first, second,
376					      (int)third | IPC_64,
377					      (unsigned long) ptr);
378			goto out;
379		}
380		default:
381			err = -ENOSYS;
382			goto out;
383		}
384	}
385	if (call <= MSGCTL) {
386		switch (call) {
387		case MSGSND:
388			err = ksys_msgsnd(first, ptr, (size_t)second,
389					 (int)third);
390			goto out;
391		case MSGRCV:
392			err = ksys_msgrcv(first, ptr, (size_t)second, fifth,
393					 (int)third);
394			goto out;
395		case MSGGET:
396			err = ksys_msgget((key_t)first, (int)second);
397			goto out;
398		case MSGCTL:
399			err = ksys_old_msgctl(first, (int)second | IPC_64, ptr);
400			goto out;
401		default:
402			err = -ENOSYS;
403			goto out;
404		}
405	}
406	if (call <= SHMCTL) {
407		switch (call) {
408		case SHMAT: {
409			ulong raddr;
410			err = do_shmat(first, ptr, (int)second, &raddr, SHMLBA);
411			if (!err) {
412				if (put_user(raddr,
413					     (ulong __user *) third))
414					err = -EFAULT;
415			}
416			goto out;
417		}
418		case SHMDT:
419			err = ksys_shmdt(ptr);
420			goto out;
421		case SHMGET:
422			err = ksys_shmget(first, (size_t)second, (int)third);
423			goto out;
424		case SHMCTL:
425			err = ksys_old_shmctl(first, (int)second | IPC_64, ptr);
426			goto out;
427		default:
428			err = -ENOSYS;
429			goto out;
430		}
431	} else {
432		err = -ENOSYS;
433	}
434out:
435	return err;
436}
437
438SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
439{
440	long ret;
441
442	if (personality(current->personality) == PER_LINUX32 &&
443	    personality(personality) == PER_LINUX)
444		personality |= PER_LINUX32;
445	ret = sys_personality(personality);
446	if (personality(ret) == PER_LINUX32)
447		ret &= ~PER_LINUX32;
448
449	return ret;
450}
451
452int sparc_mmap_check(unsigned long addr, unsigned long len)
453{
454	if (test_thread_flag(TIF_32BIT)) {
455		if (len >= STACK_TOP32)
456			return -EINVAL;
457
458		if (addr > STACK_TOP32 - len)
459			return -EINVAL;
460	} else {
461		if (len >= VA_EXCLUDE_START)
462			return -EINVAL;
463
464		if (invalid_64bit_range(addr, len))
465			return -EINVAL;
466	}
467
468	return 0;
469}
470
471/* Linux version of mmap */
472SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
473		unsigned long, prot, unsigned long, flags, unsigned long, fd,
474		unsigned long, off)
475{
476	unsigned long retval = -EINVAL;
477
478	if ((off + PAGE_ALIGN(len)) < off)
479		goto out;
480	if (off & ~PAGE_MASK)
481		goto out;
482	retval = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
483out:
484	return retval;
485}
486
487SYSCALL_DEFINE2(64_munmap, unsigned long, addr, size_t, len)
488{
489	if (invalid_64bit_range(addr, len))
490		return -EINVAL;
491
492	return vm_munmap(addr, len);
493}
494                
495SYSCALL_DEFINE5(64_mremap, unsigned long, addr,	unsigned long, old_len,
496		unsigned long, new_len, unsigned long, flags,
497		unsigned long, new_addr)
498{
499	if (test_thread_flag(TIF_32BIT))
500		return -EINVAL;
501	return sys_mremap(addr, old_len, new_len, flags, new_addr);
502}
503
504SYSCALL_DEFINE0(nis_syscall)
505{
506	static int count;
507	struct pt_regs *regs = current_pt_regs();
508	
509	/* Don't make the system unusable, if someone goes stuck */
510	if (count++ > 5)
511		return -ENOSYS;
512
513	printk ("Unimplemented SPARC system call %ld\n",regs->u_regs[1]);
514#ifdef DEBUG_UNIMP_SYSCALL	
515	show_regs (regs);
516#endif
517
518	return -ENOSYS;
519}
520
521/* #define DEBUG_SPARC_BREAKPOINT */
522
523asmlinkage void sparc_breakpoint(struct pt_regs *regs)
524{
525	enum ctx_state prev_state = exception_enter();
526
527	if (test_thread_flag(TIF_32BIT)) {
528		regs->tpc &= 0xffffffff;
529		regs->tnpc &= 0xffffffff;
530	}
531#ifdef DEBUG_SPARC_BREAKPOINT
532        printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
533#endif
534	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
535#ifdef DEBUG_SPARC_BREAKPOINT
536	printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
537#endif
538	exception_exit(prev_state);
539}
540
541SYSCALL_DEFINE2(getdomainname, char __user *, name, int, len)
542{
543	int nlen, err;
544	char tmp[__NEW_UTS_LEN + 1];
545
546	if (len < 0)
547		return -EINVAL;
548
549	down_read(&uts_sem);
550
551	nlen = strlen(utsname()->domainname) + 1;
552	err = -EINVAL;
553	if (nlen > len)
554		goto out_unlock;
555	memcpy(tmp, utsname()->domainname, nlen);
556
557	up_read(&uts_sem);
558
559	if (copy_to_user(name, tmp, nlen))
560		return -EFAULT;
561	return 0;
562
563out_unlock:
564	up_read(&uts_sem);
565	return err;
566}
567
568SYSCALL_DEFINE1(sparc_adjtimex, struct __kernel_timex __user *, txc_p)
569{
570	struct __kernel_timex txc;
571	struct __kernel_old_timeval *tv = (void *)&txc.time;
572	int ret;
573
574	/* Copy the user data space into the kernel copy
575	 * structure. But bear in mind that the structures
576	 * may change
577	 */
578	if (copy_from_user(&txc, txc_p, sizeof(txc)))
579		return -EFAULT;
580
581	/*
582	 * override for sparc64 specific timeval type: tv_usec
583	 * is 32 bit wide instead of 64-bit in __kernel_timex
584	 */
585	txc.time.tv_usec = tv->tv_usec;
586	ret = do_adjtimex(&txc);
587	tv->tv_usec = txc.time.tv_usec;
588
589	return copy_to_user(txc_p, &txc, sizeof(txc)) ? -EFAULT : ret;
590}
591
592SYSCALL_DEFINE2(sparc_clock_adjtime, const clockid_t, which_clock,
593		struct __kernel_timex __user *, txc_p)
594{
595	struct __kernel_timex txc;
596	struct __kernel_old_timeval *tv = (void *)&txc.time;
597	int ret;
598
599	if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) {
600		pr_err_once("process %d (%s) attempted a POSIX timer syscall "
601		    "while CONFIG_POSIX_TIMERS is not set\n",
602		    current->pid, current->comm);
603
604		return -ENOSYS;
605	}
606
607	/* Copy the user data space into the kernel copy
608	 * structure. But bear in mind that the structures
609	 * may change
610	 */
611	if (copy_from_user(&txc, txc_p, sizeof(txc)))
612		return -EFAULT;
613
614	/*
615	 * override for sparc64 specific timeval type: tv_usec
616	 * is 32 bit wide instead of 64-bit in __kernel_timex
617	 */
618	txc.time.tv_usec = tv->tv_usec;
619	ret = do_clock_adjtime(which_clock, &txc);
620	tv->tv_usec = txc.time.tv_usec;
621
622	return copy_to_user(txc_p, &txc, sizeof(txc)) ? -EFAULT : ret;
623}
624
625SYSCALL_DEFINE5(utrap_install, utrap_entry_t, type,
626		utrap_handler_t, new_p, utrap_handler_t, new_d,
627		utrap_handler_t __user *, old_p,
628		utrap_handler_t __user *, old_d)
629{
630	if (type < UT_INSTRUCTION_EXCEPTION || type > UT_TRAP_INSTRUCTION_31)
631		return -EINVAL;
632	if (new_p == (utrap_handler_t)(long)UTH_NOCHANGE) {
633		if (old_p) {
634			if (!current_thread_info()->utraps) {
635				if (put_user(NULL, old_p))
636					return -EFAULT;
637			} else {
638				if (put_user((utrap_handler_t)(current_thread_info()->utraps[type]), old_p))
639					return -EFAULT;
640			}
641		}
642		if (old_d) {
643			if (put_user(NULL, old_d))
644				return -EFAULT;
645		}
646		return 0;
647	}
648	if (!current_thread_info()->utraps) {
649		current_thread_info()->utraps =
650			kcalloc(UT_TRAP_INSTRUCTION_31 + 1, sizeof(long),
651				GFP_KERNEL);
652		if (!current_thread_info()->utraps)
653			return -ENOMEM;
654		current_thread_info()->utraps[0] = 1;
655	} else {
656		if ((utrap_handler_t)current_thread_info()->utraps[type] != new_p &&
657		    current_thread_info()->utraps[0] > 1) {
658			unsigned long *p = current_thread_info()->utraps;
659
660			current_thread_info()->utraps =
661				kmalloc_array(UT_TRAP_INSTRUCTION_31 + 1,
662					      sizeof(long),
663					      GFP_KERNEL);
664			if (!current_thread_info()->utraps) {
665				current_thread_info()->utraps = p;
666				return -ENOMEM;
667			}
668			p[0]--;
669			current_thread_info()->utraps[0] = 1;
670			memcpy(current_thread_info()->utraps+1, p+1,
671			       UT_TRAP_INSTRUCTION_31*sizeof(long));
672		}
673	}
674	if (old_p) {
675		if (put_user((utrap_handler_t)(current_thread_info()->utraps[type]), old_p))
676			return -EFAULT;
677	}
678	if (old_d) {
679		if (put_user(NULL, old_d))
680			return -EFAULT;
681	}
682	current_thread_info()->utraps[type] = (long)new_p;
683
684	return 0;
685}
686
687SYSCALL_DEFINE1(memory_ordering, unsigned long, model)
688{
689	struct pt_regs *regs = current_pt_regs();
690	if (model >= 3)
691		return -EINVAL;
692	regs->tstate = (regs->tstate & ~TSTATE_MM) | (model << 14);
693	return 0;
694}
695
696SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
697		struct sigaction __user *, oact, void __user *, restorer,
698		size_t, sigsetsize)
699{
700	struct k_sigaction new_ka, old_ka;
701	int ret;
702
703	/* XXX: Don't preclude handling different sized sigset_t's.  */
704	if (sigsetsize != sizeof(sigset_t))
705		return -EINVAL;
706
707	if (act) {
708		new_ka.ka_restorer = restorer;
709		if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
710			return -EFAULT;
711	}
712
713	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
714
715	if (!ret && oact) {
716		if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
717			return -EFAULT;
718	}
719
720	return ret;
721}
722
723SYSCALL_DEFINE0(kern_features)
724{
725	return KERN_FEATURE_MIXED_MODE_STACK;
726}