1 // SPDX-License-Identifier: GPL-2.0
2 /* linux/arch/sparc/kernel/signal.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
6 * Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
7 * Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be)
8 */
9
10 #include <linux/sched.h>
11 #include <linux/kernel.h>
12 #include <linux/signal.h>
13 #include <linux/errno.h>
14 #include <linux/wait.h>
15 #include <linux/ptrace.h>
16 #include <linux/unistd.h>
17 #include <linux/mm.h>
18 #include <linux/tty.h>
19 #include <linux/smp.h>
20 #include <linux/binfmts.h> /* do_coredum */
21 #include <linux/bitops.h>
22 #include <linux/resume_user_mode.h>
23
24 #include <linux/uaccess.h>
25 #include <asm/ptrace.h>
26 #include <asm/cacheflush.h> /* flush_sig_insns */
27 #include <asm/switch_to.h>
28
29 #include "sigutil.h"
30 #include "kernel.h"
31
32 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
33 void *fpqueue, unsigned long *fpqdepth);
34 extern void fpload(unsigned long *fpregs, unsigned long *fsr);
35
36 struct signal_frame {
37 struct sparc_stackf ss;
38 __siginfo32_t info;
39 __siginfo_fpu_t __user *fpu_save;
40 unsigned long insns[2] __attribute__ ((aligned (8)));
41 unsigned int extramask[_NSIG_WORDS - 1];
42 unsigned int extra_size; /* Should be 0 */
43 __siginfo_rwin_t __user *rwin_save;
44 } __attribute__((aligned(8)));
45
46 struct rt_signal_frame {
47 struct sparc_stackf ss;
48 siginfo_t info;
49 struct pt_regs regs;
50 sigset_t mask;
51 __siginfo_fpu_t __user *fpu_save;
52 unsigned int insns[2];
53 stack_t stack;
54 unsigned int extra_size; /* Should be 0 */
55 __siginfo_rwin_t __user *rwin_save;
56 } __attribute__((aligned(8)));
57
58 /* Align macros */
59 #define SF_ALIGNEDSZ (((sizeof(struct signal_frame) + 7) & (~7)))
60 #define RT_ALIGNEDSZ (((sizeof(struct rt_signal_frame) + 7) & (~7)))
61
62 /* Checks if the fp is valid. We always build signal frames which are
63 * 16-byte aligned, therefore we can always enforce that the restore
64 * frame has that property as well.
65 */
invalid_frame_pointer(void __user * fp,int fplen)66 static inline bool invalid_frame_pointer(void __user *fp, int fplen)
67 {
68 if ((((unsigned long) fp) & 15) || !access_ok(fp, fplen))
69 return true;
70
71 return false;
72 }
73
do_sigreturn(struct pt_regs * regs)74 asmlinkage void do_sigreturn(struct pt_regs *regs)
75 {
76 unsigned long up_psr, pc, npc, ufp;
77 struct signal_frame __user *sf;
78 sigset_t set;
79 __siginfo_fpu_t __user *fpu_save;
80 __siginfo_rwin_t __user *rwin_save;
81 int err;
82
83 /* Always make any pending restarted system calls return -EINTR */
84 current->restart_block.fn = do_no_restart_syscall;
85
86 synchronize_user_stack();
87
88 sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
89
90 /* 1. Make sure we are not getting garbage from the user */
91 if (invalid_frame_pointer(sf, sizeof(*sf)))
92 goto segv_and_exit;
93
94 if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP]))
95 goto segv_and_exit;
96
97 if (ufp & 0x7)
98 goto segv_and_exit;
99
100 err = __get_user(pc, &sf->info.si_regs.pc);
101 err |= __get_user(npc, &sf->info.si_regs.npc);
102
103 if ((pc | npc) & 3)
104 goto segv_and_exit;
105
106 /* 2. Restore the state */
107 up_psr = regs->psr;
108 err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
109
110 /* User can only change condition codes and FPU enabling in %psr. */
111 regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
112 | (regs->psr & (PSR_ICC | PSR_EF));
113
114 /* Prevent syscall restart. */
115 pt_regs_clear_syscall(regs);
116
117 err |= __get_user(fpu_save, &sf->fpu_save);
118 if (fpu_save)
119 err |= restore_fpu_state(regs, fpu_save);
120 err |= __get_user(rwin_save, &sf->rwin_save);
121 if (rwin_save)
122 err |= restore_rwin_state(rwin_save);
123
124 /* This is pretty much atomic, no amount locking would prevent
125 * the races which exist anyways.
126 */
127 err |= __get_user(set.sig[0], &sf->info.si_mask);
128 err |= __copy_from_user(&set.sig[1], &sf->extramask,
129 (_NSIG_WORDS-1) * sizeof(unsigned int));
130
131 if (err)
132 goto segv_and_exit;
133
134 set_current_blocked(&set);
135 return;
136
137 segv_and_exit:
138 force_sig(SIGSEGV);
139 }
140
do_rt_sigreturn(struct pt_regs * regs)141 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
142 {
143 struct rt_signal_frame __user *sf;
144 unsigned int psr, pc, npc, ufp;
145 __siginfo_fpu_t __user *fpu_save;
146 __siginfo_rwin_t __user *rwin_save;
147 sigset_t set;
148 int err;
149
150 synchronize_user_stack();
151 sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
152 if (invalid_frame_pointer(sf, sizeof(*sf)))
153 goto segv;
154
155 if (get_user(ufp, &sf->regs.u_regs[UREG_FP]))
156 goto segv;
157
158 if (ufp & 0x7)
159 goto segv;
160
161 err = __get_user(pc, &sf->regs.pc);
162 err |= __get_user(npc, &sf->regs.npc);
163 err |= ((pc | npc) & 0x03);
164
165 err |= __get_user(regs->y, &sf->regs.y);
166 err |= __get_user(psr, &sf->regs.psr);
167
168 err |= __copy_from_user(®s->u_regs[UREG_G1],
169 &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
170
171 regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
172
173 /* Prevent syscall restart. */
174 pt_regs_clear_syscall(regs);
175
176 err |= __get_user(fpu_save, &sf->fpu_save);
177 if (!err && fpu_save)
178 err |= restore_fpu_state(regs, fpu_save);
179 err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
180 err |= restore_altstack(&sf->stack);
181
182 if (err)
183 goto segv;
184
185 regs->pc = pc;
186 regs->npc = npc;
187
188 err |= __get_user(rwin_save, &sf->rwin_save);
189 if (!err && rwin_save) {
190 if (restore_rwin_state(rwin_save))
191 goto segv;
192 }
193
194 set_current_blocked(&set);
195 return;
196 segv:
197 force_sig(SIGSEGV);
198 }
199
get_sigframe(struct ksignal * ksig,struct pt_regs * regs,unsigned long framesize)200 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
201 {
202 unsigned long sp = regs->u_regs[UREG_FP];
203
204 /*
205 * If we are on the alternate signal stack and would overflow it, don't.
206 * Return an always-bogus address instead so we will die with SIGSEGV.
207 */
208 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
209 return (void __user *) -1L;
210
211 /* This is the X/Open sanctioned signal stack switching. */
212 sp = sigsp(sp, ksig) - framesize;
213
214 /* Always align the stack frame. This handles two cases. First,
215 * sigaltstack need not be mindful of platform specific stack
216 * alignment. Second, if we took this signal because the stack
217 * is not aligned properly, we'd like to take the signal cleanly
218 * and report that.
219 */
220 sp &= ~15UL;
221
222 return (void __user *) sp;
223 }
224
setup_frame(struct ksignal * ksig,struct pt_regs * regs,sigset_t * oldset)225 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs,
226 sigset_t *oldset)
227 {
228 struct signal_frame __user *sf;
229 int sigframe_size, err, wsaved;
230 void __user *tail;
231
232 /* 1. Make sure everything is clean */
233 synchronize_user_stack();
234
235 wsaved = current_thread_info()->w_saved;
236
237 sigframe_size = sizeof(*sf);
238 if (used_math())
239 sigframe_size += sizeof(__siginfo_fpu_t);
240 if (wsaved)
241 sigframe_size += sizeof(__siginfo_rwin_t);
242
243 sf = (struct signal_frame __user *)
244 get_sigframe(ksig, regs, sigframe_size);
245
246 if (invalid_frame_pointer(sf, sigframe_size)) {
247 force_exit_sig(SIGILL);
248 return -EINVAL;
249 }
250
251 tail = sf + 1;
252
253 /* 2. Save the current process state */
254 err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
255
256 err |= __put_user(0, &sf->extra_size);
257
258 if (used_math()) {
259 __siginfo_fpu_t __user *fp = tail;
260 tail += sizeof(*fp);
261 err |= save_fpu_state(regs, fp);
262 err |= __put_user(fp, &sf->fpu_save);
263 } else {
264 err |= __put_user(0, &sf->fpu_save);
265 }
266 if (wsaved) {
267 __siginfo_rwin_t __user *rwp = tail;
268 tail += sizeof(*rwp);
269 err |= save_rwin_state(wsaved, rwp);
270 err |= __put_user(rwp, &sf->rwin_save);
271 } else {
272 err |= __put_user(0, &sf->rwin_save);
273 }
274
275 err |= __put_user(oldset->sig[0], &sf->info.si_mask);
276 err |= __copy_to_user(sf->extramask, &oldset->sig[1],
277 (_NSIG_WORDS - 1) * sizeof(unsigned int));
278 if (!wsaved) {
279 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
280 sizeof(struct reg_window32));
281 } else {
282 struct reg_window32 *rp;
283
284 rp = ¤t_thread_info()->reg_window[wsaved - 1];
285 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
286 }
287 if (err)
288 return err;
289
290 /* 3. signal handler back-trampoline and parameters */
291 regs->u_regs[UREG_FP] = (unsigned long) sf;
292 regs->u_regs[UREG_I0] = ksig->sig;
293 regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
294 regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
295
296 /* 4. signal handler */
297 regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
298 regs->npc = (regs->pc + 4);
299
300 /* 5. return to kernel instructions */
301 if (ksig->ka.ka_restorer)
302 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
303 else {
304 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
305
306 /* mov __NR_sigreturn, %g1 */
307 err |= __put_user(0x821020d8, &sf->insns[0]);
308
309 /* t 0x10 */
310 err |= __put_user(0x91d02010, &sf->insns[1]);
311 if (err)
312 return err;
313
314 /* Flush instruction space. */
315 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
316 }
317 return 0;
318 }
319
setup_rt_frame(struct ksignal * ksig,struct pt_regs * regs,sigset_t * oldset)320 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs,
321 sigset_t *oldset)
322 {
323 struct rt_signal_frame __user *sf;
324 int sigframe_size, wsaved;
325 void __user *tail;
326 unsigned int psr;
327 int err;
328
329 synchronize_user_stack();
330 wsaved = current_thread_info()->w_saved;
331 sigframe_size = sizeof(*sf);
332 if (used_math())
333 sigframe_size += sizeof(__siginfo_fpu_t);
334 if (wsaved)
335 sigframe_size += sizeof(__siginfo_rwin_t);
336 sf = (struct rt_signal_frame __user *)
337 get_sigframe(ksig, regs, sigframe_size);
338 if (invalid_frame_pointer(sf, sigframe_size)) {
339 force_exit_sig(SIGILL);
340 return -EINVAL;
341 }
342
343 tail = sf + 1;
344 err = __put_user(regs->pc, &sf->regs.pc);
345 err |= __put_user(regs->npc, &sf->regs.npc);
346 err |= __put_user(regs->y, &sf->regs.y);
347 psr = regs->psr;
348 if (used_math())
349 psr |= PSR_EF;
350 err |= __put_user(psr, &sf->regs.psr);
351 err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
352 err |= __put_user(0, &sf->extra_size);
353
354 if (psr & PSR_EF) {
355 __siginfo_fpu_t __user *fp = tail;
356 tail += sizeof(*fp);
357 err |= save_fpu_state(regs, fp);
358 err |= __put_user(fp, &sf->fpu_save);
359 } else {
360 err |= __put_user(0, &sf->fpu_save);
361 }
362 if (wsaved) {
363 __siginfo_rwin_t __user *rwp = tail;
364 tail += sizeof(*rwp);
365 err |= save_rwin_state(wsaved, rwp);
366 err |= __put_user(rwp, &sf->rwin_save);
367 } else {
368 err |= __put_user(0, &sf->rwin_save);
369 }
370 err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
371
372 /* Setup sigaltstack */
373 err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
374
375 if (!wsaved) {
376 err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
377 sizeof(struct reg_window32));
378 } else {
379 struct reg_window32 *rp;
380
381 rp = ¤t_thread_info()->reg_window[wsaved - 1];
382 err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
383 }
384
385 err |= copy_siginfo_to_user(&sf->info, &ksig->info);
386
387 if (err)
388 return err;
389
390 regs->u_regs[UREG_FP] = (unsigned long) sf;
391 regs->u_regs[UREG_I0] = ksig->sig;
392 regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
393 regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
394
395 regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
396 regs->npc = (regs->pc + 4);
397
398 if (ksig->ka.ka_restorer)
399 regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
400 else {
401 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
402
403 /* mov __NR_rt_sigreturn, %g1 */
404 err |= __put_user(0x82102065, &sf->insns[0]);
405
406 /* t 0x10 */
407 err |= __put_user(0x91d02010, &sf->insns[1]);
408 if (err)
409 return err;
410
411 /* Flush instruction space. */
412 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
413 }
414 return 0;
415 }
416
417 static inline void
handle_signal(struct ksignal * ksig,struct pt_regs * regs)418 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
419 {
420 sigset_t *oldset = sigmask_to_save();
421 int err;
422
423 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
424 err = setup_rt_frame(ksig, regs, oldset);
425 else
426 err = setup_frame(ksig, regs, oldset);
427 signal_setup_done(err, ksig, 0);
428 }
429
syscall_restart(unsigned long orig_i0,struct pt_regs * regs,struct sigaction * sa)430 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
431 struct sigaction *sa)
432 {
433 switch(regs->u_regs[UREG_I0]) {
434 case ERESTART_RESTARTBLOCK:
435 case ERESTARTNOHAND:
436 no_system_call_restart:
437 regs->u_regs[UREG_I0] = EINTR;
438 regs->psr |= PSR_C;
439 break;
440 case ERESTARTSYS:
441 if (!(sa->sa_flags & SA_RESTART))
442 goto no_system_call_restart;
443 fallthrough;
444 case ERESTARTNOINTR:
445 regs->u_regs[UREG_I0] = orig_i0;
446 regs->pc -= 4;
447 regs->npc -= 4;
448 }
449 }
450
451 /* Note that 'init' is a special process: it doesn't get signals it doesn't
452 * want to handle. Thus you cannot kill init even with a SIGKILL even by
453 * mistake.
454 */
do_signal(struct pt_regs * regs,unsigned long orig_i0)455 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
456 {
457 struct ksignal ksig;
458 int restart_syscall;
459 bool has_handler;
460
461 /* It's a lot of work and synchronization to add a new ptrace
462 * register for GDB to save and restore in order to get
463 * orig_i0 correct for syscall restarts when debugging.
464 *
465 * Although it should be the case that most of the global
466 * registers are volatile across a system call, glibc already
467 * depends upon that fact that we preserve them. So we can't
468 * just use any global register to save away the orig_i0 value.
469 *
470 * In particular %g2, %g3, %g4, and %g5 are all assumed to be
471 * preserved across a system call trap by various pieces of
472 * code in glibc.
473 *
474 * %g7 is used as the "thread register". %g6 is not used in
475 * any fixed manner. %g6 is used as a scratch register and
476 * a compiler temporary, but its value is never used across
477 * a system call. Therefore %g6 is usable for orig_i0 storage.
478 */
479 if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
480 regs->u_regs[UREG_G6] = orig_i0;
481
482 has_handler = get_signal(&ksig);
483
484 /* If the debugger messes with the program counter, it clears
485 * the software "in syscall" bit, directing us to not perform
486 * a syscall restart.
487 */
488 restart_syscall = 0;
489 if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
490 restart_syscall = 1;
491 orig_i0 = regs->u_regs[UREG_G6];
492 }
493
494 if (has_handler) {
495 if (restart_syscall)
496 syscall_restart(orig_i0, regs, &ksig.ka.sa);
497 handle_signal(&ksig, regs);
498 } else {
499 if (restart_syscall) {
500 switch (regs->u_regs[UREG_I0]) {
501 case ERESTARTNOHAND:
502 case ERESTARTSYS:
503 case ERESTARTNOINTR:
504 /* replay the system call when we are done */
505 regs->u_regs[UREG_I0] = orig_i0;
506 regs->pc -= 4;
507 regs->npc -= 4;
508 pt_regs_clear_syscall(regs);
509 fallthrough;
510 case ERESTART_RESTARTBLOCK:
511 regs->u_regs[UREG_G1] = __NR_restart_syscall;
512 regs->pc -= 4;
513 regs->npc -= 4;
514 pt_regs_clear_syscall(regs);
515 }
516 }
517 restore_saved_sigmask();
518 }
519 }
520
do_notify_resume(struct pt_regs * regs,unsigned long orig_i0,unsigned long thread_info_flags)521 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
522 unsigned long thread_info_flags)
523 {
524 if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
525 do_signal(regs, orig_i0);
526 if (thread_info_flags & _TIF_NOTIFY_RESUME)
527 resume_user_mode_work(regs);
528 }
529
do_sys_sigstack(struct sigstack __user * ssptr,struct sigstack __user * ossptr,unsigned long sp)530 asmlinkage int do_sys_sigstack(struct sigstack __user *ssptr,
531 struct sigstack __user *ossptr,
532 unsigned long sp)
533 {
534 int ret = -EFAULT;
535
536 /* First see if old state is wanted. */
537 if (ossptr) {
538 if (put_user(current->sas_ss_sp + current->sas_ss_size,
539 &ossptr->the_stack) ||
540 __put_user(on_sig_stack(sp), &ossptr->cur_status))
541 goto out;
542 }
543
544 /* Now see if we want to update the new state. */
545 if (ssptr) {
546 char *ss_sp;
547
548 if (get_user(ss_sp, &ssptr->the_stack))
549 goto out;
550 /* If the current stack was set with sigaltstack, don't
551 swap stacks while we are on it. */
552 ret = -EPERM;
553 if (current->sas_ss_sp && on_sig_stack(sp))
554 goto out;
555
556 /* Since we don't know the extent of the stack, and we don't
557 track onstack-ness, but rather calculate it, we must
558 presume a size. Ho hum this interface is lossy. */
559 current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
560 current->sas_ss_size = SIGSTKSZ;
561 }
562 ret = 0;
563 out:
564 return ret;
565 }
566