Merge tag 'for-5.15/parisc' of git://git.kernel.org/pub/scm/linux/kernel/git/deller...
[linux-2.6-microblaze.git] / arch / sparc / kernel / 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
34 #include <asm/utrap.h>
35 #include <asm/unistd.h>
36
37 #include "entry.h"
38 #include "kernel.h"
39 #include "systbls.h"
40
41 /* #define DEBUG_UNIMP_SYSCALL */
42
43 SYSCALL_DEFINE0(getpagesize)
44 {
45         return PAGE_SIZE;
46 }
47
48 /* Does addr --> addr+len fall within 4GB of the VA-space hole or
49  * overflow past the end of the 64-bit address space?
50  */
51 static inline int invalid_64bit_range(unsigned long addr, unsigned long len)
52 {
53         unsigned long va_exclude_start, va_exclude_end;
54
55         va_exclude_start = VA_EXCLUDE_START;
56         va_exclude_end   = VA_EXCLUDE_END;
57
58         if (unlikely(len >= va_exclude_start))
59                 return 1;
60
61         if (unlikely((addr + len) < addr))
62                 return 1;
63
64         if (unlikely((addr >= va_exclude_start && addr < va_exclude_end) ||
65                      ((addr + len) >= va_exclude_start &&
66                       (addr + len) < va_exclude_end)))
67                 return 1;
68
69         return 0;
70 }
71
72 /* These functions differ from the default implementations in
73  * mm/mmap.c in two ways:
74  *
75  * 1) For file backed MAP_SHARED mmap()'s we D-cache color align,
76  *    for fixed such mappings we just validate what the user gave us.
77  * 2) For 64-bit tasks we avoid mapping anything within 4GB of
78  *    the spitfire/niagara VA-hole.
79  */
80
81 static inline unsigned long COLOR_ALIGN(unsigned long addr,
82                                          unsigned long pgoff)
83 {
84         unsigned long base = (addr+SHMLBA-1)&~(SHMLBA-1);
85         unsigned long off = (pgoff<<PAGE_SHIFT) & (SHMLBA-1);
86
87         return base + off;
88 }
89
90 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags)
91 {
92         struct mm_struct *mm = current->mm;
93         struct vm_area_struct * vma;
94         unsigned long task_size = TASK_SIZE;
95         int do_color_align;
96         struct vm_unmapped_area_info info;
97
98         if (flags & MAP_FIXED) {
99                 /* We do not accept a shared mapping if it would violate
100                  * cache aliasing constraints.
101                  */
102                 if ((flags & MAP_SHARED) &&
103                     ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
104                         return -EINVAL;
105                 return addr;
106         }
107
108         if (test_thread_flag(TIF_32BIT))
109                 task_size = STACK_TOP32;
110         if (unlikely(len > task_size || len >= VA_EXCLUDE_START))
111                 return -ENOMEM;
112
113         do_color_align = 0;
114         if (filp || (flags & MAP_SHARED))
115                 do_color_align = 1;
116
117         if (addr) {
118                 if (do_color_align)
119                         addr = COLOR_ALIGN(addr, pgoff);
120                 else
121                         addr = PAGE_ALIGN(addr);
122
123                 vma = find_vma(mm, addr);
124                 if (task_size - len >= addr &&
125                     (!vma || addr + len <= vm_start_gap(vma)))
126                         return addr;
127         }
128
129         info.flags = 0;
130         info.length = len;
131         info.low_limit = TASK_UNMAPPED_BASE;
132         info.high_limit = min(task_size, VA_EXCLUDE_START);
133         info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
134         info.align_offset = pgoff << PAGE_SHIFT;
135         addr = vm_unmapped_area(&info);
136
137         if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
138                 VM_BUG_ON(addr != -ENOMEM);
139                 info.low_limit = VA_EXCLUDE_END;
140                 info.high_limit = task_size;
141                 addr = vm_unmapped_area(&info);
142         }
143
144         return addr;
145 }
146
147 unsigned long
148 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
149                           const unsigned long len, const unsigned long pgoff,
150                           const unsigned long flags)
151 {
152         struct vm_area_struct *vma;
153         struct mm_struct *mm = current->mm;
154         unsigned long task_size = STACK_TOP32;
155         unsigned long addr = addr0;
156         int do_color_align;
157         struct vm_unmapped_area_info info;
158
159         /* This should only ever run for 32-bit processes.  */
160         BUG_ON(!test_thread_flag(TIF_32BIT));
161
162         if (flags & MAP_FIXED) {
163                 /* We do not accept a shared mapping if it would violate
164                  * cache aliasing constraints.
165                  */
166                 if ((flags & MAP_SHARED) &&
167                     ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
168                         return -EINVAL;
169                 return addr;
170         }
171
172         if (unlikely(len > task_size))
173                 return -ENOMEM;
174
175         do_color_align = 0;
176         if (filp || (flags & MAP_SHARED))
177                 do_color_align = 1;
178
179         /* requesting a specific address */
180         if (addr) {
181                 if (do_color_align)
182                         addr = COLOR_ALIGN(addr, pgoff);
183                 else
184                         addr = PAGE_ALIGN(addr);
185
186                 vma = find_vma(mm, addr);
187                 if (task_size - len >= addr &&
188                     (!vma || addr + len <= vm_start_gap(vma)))
189                         return addr;
190         }
191
192         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
193         info.length = len;
194         info.low_limit = PAGE_SIZE;
195         info.high_limit = mm->mmap_base;
196         info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
197         info.align_offset = pgoff << PAGE_SHIFT;
198         addr = vm_unmapped_area(&info);
199
200         /*
201          * A failed mmap() very likely causes application failure,
202          * so fall back to the bottom-up function here. This scenario
203          * can happen with large stack limits and large mmap()
204          * allocations.
205          */
206         if (addr & ~PAGE_MASK) {
207                 VM_BUG_ON(addr != -ENOMEM);
208                 info.flags = 0;
209                 info.low_limit = TASK_UNMAPPED_BASE;
210                 info.high_limit = STACK_TOP32;
211                 addr = vm_unmapped_area(&info);
212         }
213
214         return addr;
215 }
216
217 /* Try to align mapping such that we align it as much as possible. */
218 unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
219 {
220         unsigned long align_goal, addr = -ENOMEM;
221         unsigned long (*get_area)(struct file *, unsigned long,
222                                   unsigned long, unsigned long, unsigned long);
223
224         get_area = current->mm->get_unmapped_area;
225
226         if (flags & MAP_FIXED) {
227                 /* Ok, don't mess with it. */
228                 return get_area(NULL, orig_addr, len, pgoff, flags);
229         }
230         flags &= ~MAP_SHARED;
231
232         align_goal = PAGE_SIZE;
233         if (len >= (4UL * 1024 * 1024))
234                 align_goal = (4UL * 1024 * 1024);
235         else if (len >= (512UL * 1024))
236                 align_goal = (512UL * 1024);
237         else if (len >= (64UL * 1024))
238                 align_goal = (64UL * 1024);
239
240         do {
241                 addr = get_area(NULL, orig_addr, len + (align_goal - PAGE_SIZE), pgoff, flags);
242                 if (!(addr & ~PAGE_MASK)) {
243                         addr = (addr + (align_goal - 1UL)) & ~(align_goal - 1UL);
244                         break;
245                 }
246
247                 if (align_goal == (4UL * 1024 * 1024))
248                         align_goal = (512UL * 1024);
249                 else if (align_goal == (512UL * 1024))
250                         align_goal = (64UL * 1024);
251                 else
252                         align_goal = PAGE_SIZE;
253         } while ((addr & ~PAGE_MASK) && align_goal > PAGE_SIZE);
254
255         /* Mapping is smaller than 64K or larger areas could not
256          * be obtained.
257          */
258         if (addr & ~PAGE_MASK)
259                 addr = get_area(NULL, orig_addr, len, pgoff, flags);
260
261         return addr;
262 }
263 EXPORT_SYMBOL(get_fb_unmapped_area);
264
265 /* Essentially the same as PowerPC.  */
266 static unsigned long mmap_rnd(void)
267 {
268         unsigned long rnd = 0UL;
269
270         if (current->flags & PF_RANDOMIZE) {
271                 unsigned long val = get_random_long();
272                 if (test_thread_flag(TIF_32BIT))
273                         rnd = (val % (1UL << (23UL-PAGE_SHIFT)));
274                 else
275                         rnd = (val % (1UL << (30UL-PAGE_SHIFT)));
276         }
277         return rnd << PAGE_SHIFT;
278 }
279
280 void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
281 {
282         unsigned long random_factor = mmap_rnd();
283         unsigned long gap;
284
285         /*
286          * Fall back to the standard layout if the personality
287          * bit is set, or if the expected stack growth is unlimited:
288          */
289         gap = rlim_stack->rlim_cur;
290         if (!test_thread_flag(TIF_32BIT) ||
291             (current->personality & ADDR_COMPAT_LAYOUT) ||
292             gap == RLIM_INFINITY ||
293             sysctl_legacy_va_layout) {
294                 mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
295                 mm->get_unmapped_area = arch_get_unmapped_area;
296         } else {
297                 /* We know it's 32-bit */
298                 unsigned long task_size = STACK_TOP32;
299
300                 if (gap < 128 * 1024 * 1024)
301                         gap = 128 * 1024 * 1024;
302                 if (gap > (task_size / 6 * 5))
303                         gap = (task_size / 6 * 5);
304
305                 mm->mmap_base = PAGE_ALIGN(task_size - gap - random_factor);
306                 mm->get_unmapped_area = arch_get_unmapped_area_topdown;
307         }
308 }
309
310 /*
311  * sys_pipe() is the normal C calling standard for creating
312  * a pipe. It's not the way unix traditionally does this, though.
313  */
314 SYSCALL_DEFINE0(sparc_pipe)
315 {
316         int fd[2];
317         int error;
318
319         error = do_pipe_flags(fd, 0);
320         if (error)
321                 goto out;
322         current_pt_regs()->u_regs[UREG_I1] = fd[1];
323         error = fd[0];
324 out:
325         return error;
326 }
327
328 /*
329  * sys_ipc() is the de-multiplexer for the SysV IPC calls..
330  *
331  * This is really horribly ugly.
332  */
333
334 SYSCALL_DEFINE6(sparc_ipc, unsigned int, call, int, first, unsigned long, second,
335                 unsigned long, third, void __user *, ptr, long, fifth)
336 {
337         long err;
338
339         if (!IS_ENABLED(CONFIG_SYSVIPC))
340                 return -ENOSYS;
341
342         /* No need for backward compatibility. We can start fresh... */
343         if (call <= SEMTIMEDOP) {
344                 switch (call) {
345                 case SEMOP:
346                         err = ksys_semtimedop(first, ptr,
347                                               (unsigned int)second, NULL);
348                         goto out;
349                 case SEMTIMEDOP:
350                         err = ksys_semtimedop(first, ptr, (unsigned int)second,
351                                 (const struct __kernel_timespec __user *)
352                                               (unsigned long) fifth);
353                         goto out;
354                 case SEMGET:
355                         err = ksys_semget(first, (int)second, (int)third);
356                         goto out;
357                 case SEMCTL: {
358                         err = ksys_old_semctl(first, second,
359                                               (int)third | IPC_64,
360                                               (unsigned long) ptr);
361                         goto out;
362                 }
363                 default:
364                         err = -ENOSYS;
365                         goto out;
366                 }
367         }
368         if (call <= MSGCTL) {
369                 switch (call) {
370                 case MSGSND:
371                         err = ksys_msgsnd(first, ptr, (size_t)second,
372                                          (int)third);
373                         goto out;
374                 case MSGRCV:
375                         err = ksys_msgrcv(first, ptr, (size_t)second, fifth,
376                                          (int)third);
377                         goto out;
378                 case MSGGET:
379                         err = ksys_msgget((key_t)first, (int)second);
380                         goto out;
381                 case MSGCTL:
382                         err = ksys_old_msgctl(first, (int)second | IPC_64, ptr);
383                         goto out;
384                 default:
385                         err = -ENOSYS;
386                         goto out;
387                 }
388         }
389         if (call <= SHMCTL) {
390                 switch (call) {
391                 case SHMAT: {
392                         ulong raddr;
393                         err = do_shmat(first, ptr, (int)second, &raddr, SHMLBA);
394                         if (!err) {
395                                 if (put_user(raddr,
396                                              (ulong __user *) third))
397                                         err = -EFAULT;
398                         }
399                         goto out;
400                 }
401                 case SHMDT:
402                         err = ksys_shmdt(ptr);
403                         goto out;
404                 case SHMGET:
405                         err = ksys_shmget(first, (size_t)second, (int)third);
406                         goto out;
407                 case SHMCTL:
408                         err = ksys_old_shmctl(first, (int)second | IPC_64, ptr);
409                         goto out;
410                 default:
411                         err = -ENOSYS;
412                         goto out;
413                 }
414         } else {
415                 err = -ENOSYS;
416         }
417 out:
418         return err;
419 }
420
421 SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
422 {
423         long ret;
424
425         if (personality(current->personality) == PER_LINUX32 &&
426             personality(personality) == PER_LINUX)
427                 personality |= PER_LINUX32;
428         ret = sys_personality(personality);
429         if (personality(ret) == PER_LINUX32)
430                 ret &= ~PER_LINUX32;
431
432         return ret;
433 }
434
435 int sparc_mmap_check(unsigned long addr, unsigned long len)
436 {
437         if (test_thread_flag(TIF_32BIT)) {
438                 if (len >= STACK_TOP32)
439                         return -EINVAL;
440
441                 if (addr > STACK_TOP32 - len)
442                         return -EINVAL;
443         } else {
444                 if (len >= VA_EXCLUDE_START)
445                         return -EINVAL;
446
447                 if (invalid_64bit_range(addr, len))
448                         return -EINVAL;
449         }
450
451         return 0;
452 }
453
454 /* Linux version of mmap */
455 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
456                 unsigned long, prot, unsigned long, flags, unsigned long, fd,
457                 unsigned long, off)
458 {
459         unsigned long retval = -EINVAL;
460
461         if ((off + PAGE_ALIGN(len)) < off)
462                 goto out;
463         if (off & ~PAGE_MASK)
464                 goto out;
465         retval = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
466 out:
467         return retval;
468 }
469
470 SYSCALL_DEFINE2(64_munmap, unsigned long, addr, size_t, len)
471 {
472         if (invalid_64bit_range(addr, len))
473                 return -EINVAL;
474
475         return vm_munmap(addr, len);
476 }
477                 
478 SYSCALL_DEFINE5(64_mremap, unsigned long, addr, unsigned long, old_len,
479                 unsigned long, new_len, unsigned long, flags,
480                 unsigned long, new_addr)
481 {
482         if (test_thread_flag(TIF_32BIT))
483                 return -EINVAL;
484         return sys_mremap(addr, old_len, new_len, flags, new_addr);
485 }
486
487 SYSCALL_DEFINE0(nis_syscall)
488 {
489         static int count;
490         struct pt_regs *regs = current_pt_regs();
491         
492         /* Don't make the system unusable, if someone goes stuck */
493         if (count++ > 5)
494                 return -ENOSYS;
495
496         printk ("Unimplemented SPARC system call %ld\n",regs->u_regs[1]);
497 #ifdef DEBUG_UNIMP_SYSCALL      
498         show_regs (regs);
499 #endif
500
501         return -ENOSYS;
502 }
503
504 /* #define DEBUG_SPARC_BREAKPOINT */
505
506 asmlinkage void sparc_breakpoint(struct pt_regs *regs)
507 {
508         enum ctx_state prev_state = exception_enter();
509
510         if (test_thread_flag(TIF_32BIT)) {
511                 regs->tpc &= 0xffffffff;
512                 regs->tnpc &= 0xffffffff;
513         }
514 #ifdef DEBUG_SPARC_BREAKPOINT
515         printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
516 #endif
517         force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc);
518 #ifdef DEBUG_SPARC_BREAKPOINT
519         printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
520 #endif
521         exception_exit(prev_state);
522 }
523
524 SYSCALL_DEFINE2(getdomainname, char __user *, name, int, len)
525 {
526         int nlen, err;
527         char tmp[__NEW_UTS_LEN + 1];
528
529         if (len < 0)
530                 return -EINVAL;
531
532         down_read(&uts_sem);
533
534         nlen = strlen(utsname()->domainname) + 1;
535         err = -EINVAL;
536         if (nlen > len)
537                 goto out_unlock;
538         memcpy(tmp, utsname()->domainname, nlen);
539
540         up_read(&uts_sem);
541
542         if (copy_to_user(name, tmp, nlen))
543                 return -EFAULT;
544         return 0;
545
546 out_unlock:
547         up_read(&uts_sem);
548         return err;
549 }
550
551 SYSCALL_DEFINE1(sparc_adjtimex, struct __kernel_timex __user *, txc_p)
552 {
553         struct __kernel_timex txc;
554         struct __kernel_old_timeval *tv = (void *)&txc.time;
555         int ret;
556
557         /* Copy the user data space into the kernel copy
558          * structure. But bear in mind that the structures
559          * may change
560          */
561         if (copy_from_user(&txc, txc_p, sizeof(txc)))
562                 return -EFAULT;
563
564         /*
565          * override for sparc64 specific timeval type: tv_usec
566          * is 32 bit wide instead of 64-bit in __kernel_timex
567          */
568         txc.time.tv_usec = tv->tv_usec;
569         ret = do_adjtimex(&txc);
570         tv->tv_usec = txc.time.tv_usec;
571
572         return copy_to_user(txc_p, &txc, sizeof(txc)) ? -EFAULT : ret;
573 }
574
575 SYSCALL_DEFINE2(sparc_clock_adjtime, const clockid_t, which_clock,
576                 struct __kernel_timex __user *, txc_p)
577 {
578         struct __kernel_timex txc;
579         struct __kernel_old_timeval *tv = (void *)&txc.time;
580         int ret;
581
582         if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) {
583                 pr_err_once("process %d (%s) attempted a POSIX timer syscall "
584                     "while CONFIG_POSIX_TIMERS is not set\n",
585                     current->pid, current->comm);
586
587                 return -ENOSYS;
588         }
589
590         /* Copy the user data space into the kernel copy
591          * structure. But bear in mind that the structures
592          * may change
593          */
594         if (copy_from_user(&txc, txc_p, sizeof(txc)))
595                 return -EFAULT;
596
597         /*
598          * override for sparc64 specific timeval type: tv_usec
599          * is 32 bit wide instead of 64-bit in __kernel_timex
600          */
601         txc.time.tv_usec = tv->tv_usec;
602         ret = do_clock_adjtime(which_clock, &txc);
603         tv->tv_usec = txc.time.tv_usec;
604
605         return copy_to_user(txc_p, &txc, sizeof(txc)) ? -EFAULT : ret;
606 }
607
608 SYSCALL_DEFINE5(utrap_install, utrap_entry_t, type,
609                 utrap_handler_t, new_p, utrap_handler_t, new_d,
610                 utrap_handler_t __user *, old_p,
611                 utrap_handler_t __user *, old_d)
612 {
613         if (type < UT_INSTRUCTION_EXCEPTION || type > UT_TRAP_INSTRUCTION_31)
614                 return -EINVAL;
615         if (new_p == (utrap_handler_t)(long)UTH_NOCHANGE) {
616                 if (old_p) {
617                         if (!current_thread_info()->utraps) {
618                                 if (put_user(NULL, old_p))
619                                         return -EFAULT;
620                         } else {
621                                 if (put_user((utrap_handler_t)(current_thread_info()->utraps[type]), old_p))
622                                         return -EFAULT;
623                         }
624                 }
625                 if (old_d) {
626                         if (put_user(NULL, old_d))
627                                 return -EFAULT;
628                 }
629                 return 0;
630         }
631         if (!current_thread_info()->utraps) {
632                 current_thread_info()->utraps =
633                         kcalloc(UT_TRAP_INSTRUCTION_31 + 1, sizeof(long),
634                                 GFP_KERNEL);
635                 if (!current_thread_info()->utraps)
636                         return -ENOMEM;
637                 current_thread_info()->utraps[0] = 1;
638         } else {
639                 if ((utrap_handler_t)current_thread_info()->utraps[type] != new_p &&
640                     current_thread_info()->utraps[0] > 1) {
641                         unsigned long *p = current_thread_info()->utraps;
642
643                         current_thread_info()->utraps =
644                                 kmalloc_array(UT_TRAP_INSTRUCTION_31 + 1,
645                                               sizeof(long),
646                                               GFP_KERNEL);
647                         if (!current_thread_info()->utraps) {
648                                 current_thread_info()->utraps = p;
649                                 return -ENOMEM;
650                         }
651                         p[0]--;
652                         current_thread_info()->utraps[0] = 1;
653                         memcpy(current_thread_info()->utraps+1, p+1,
654                                UT_TRAP_INSTRUCTION_31*sizeof(long));
655                 }
656         }
657         if (old_p) {
658                 if (put_user((utrap_handler_t)(current_thread_info()->utraps[type]), old_p))
659                         return -EFAULT;
660         }
661         if (old_d) {
662                 if (put_user(NULL, old_d))
663                         return -EFAULT;
664         }
665         current_thread_info()->utraps[type] = (long)new_p;
666
667         return 0;
668 }
669
670 SYSCALL_DEFINE1(memory_ordering, unsigned long, model)
671 {
672         struct pt_regs *regs = current_pt_regs();
673         if (model >= 3)
674                 return -EINVAL;
675         regs->tstate = (regs->tstate & ~TSTATE_MM) | (model << 14);
676         return 0;
677 }
678
679 SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
680                 struct sigaction __user *, oact, void __user *, restorer,
681                 size_t, sigsetsize)
682 {
683         struct k_sigaction new_ka, old_ka;
684         int ret;
685
686         /* XXX: Don't preclude handling different sized sigset_t's.  */
687         if (sigsetsize != sizeof(sigset_t))
688                 return -EINVAL;
689
690         if (act) {
691                 new_ka.ka_restorer = restorer;
692                 if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
693                         return -EFAULT;
694         }
695
696         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
697
698         if (!ret && oact) {
699                 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
700                         return -EFAULT;
701         }
702
703         return ret;
704 }
705
706 SYSCALL_DEFINE0(kern_features)
707 {
708         return KERN_FEATURE_MIXED_MODE_STACK;
709 }