xref: /openbmc/linux/arch/sparc/kernel/signal_32.c (revision 002dff36)
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/tracehook.h>
23 
24 #include <linux/uaccess.h>
25 #include <asm/ptrace.h>
26 #include <asm/pgalloc.h>
27 #include <asm/cacheflush.h>	/* flush_sig_insns */
28 #include <asm/switch_to.h>
29 
30 #include "sigutil.h"
31 #include "kernel.h"
32 
33 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
34 		   void *fpqueue, unsigned long *fpqdepth);
35 extern void fpload(unsigned long *fpregs, unsigned long *fsr);
36 
37 struct signal_frame {
38 	struct sparc_stackf	ss;
39 	__siginfo32_t		info;
40 	__siginfo_fpu_t __user	*fpu_save;
41 	unsigned long		insns[2] __attribute__ ((aligned (8)));
42 	unsigned int		extramask[_NSIG_WORDS - 1];
43 	unsigned int		extra_size; /* Should be 0 */
44 	__siginfo_rwin_t __user	*rwin_save;
45 } __attribute__((aligned(8)));
46 
47 struct rt_signal_frame {
48 	struct sparc_stackf	ss;
49 	siginfo_t		info;
50 	struct pt_regs		regs;
51 	sigset_t		mask;
52 	__siginfo_fpu_t __user	*fpu_save;
53 	unsigned int		insns[2];
54 	stack_t			stack;
55 	unsigned int		extra_size; /* Should be 0 */
56 	__siginfo_rwin_t __user	*rwin_save;
57 } __attribute__((aligned(8)));
58 
59 /* Align macros */
60 #define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
61 #define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))
62 
63 /* Checks if the fp is valid.  We always build signal frames which are
64  * 16-byte aligned, therefore we can always enforce that the restore
65  * frame has that property as well.
66  */
67 static inline bool invalid_frame_pointer(void __user *fp, int fplen)
68 {
69 	if ((((unsigned long) fp) & 15) || !__access_ok((unsigned long)fp, fplen))
70 		return true;
71 
72 	return false;
73 }
74 
75 asmlinkage void do_sigreturn(struct pt_regs *regs)
76 {
77 	unsigned long up_psr, pc, npc, ufp;
78 	struct signal_frame __user *sf;
79 	sigset_t set;
80 	__siginfo_fpu_t __user *fpu_save;
81 	__siginfo_rwin_t __user *rwin_save;
82 	int err;
83 
84 	/* Always make any pending restarted system calls return -EINTR */
85 	current->restart_block.fn = do_no_restart_syscall;
86 
87 	synchronize_user_stack();
88 
89 	sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
90 
91 	/* 1. Make sure we are not getting garbage from the user */
92 	if (invalid_frame_pointer(sf, sizeof(*sf)))
93 		goto segv_and_exit;
94 
95 	if (get_user(ufp, &sf->info.si_regs.u_regs[UREG_FP]))
96 		goto segv_and_exit;
97 
98 	if (ufp & 0x7)
99 		goto segv_and_exit;
100 
101 	err = __get_user(pc,  &sf->info.si_regs.pc);
102 	err |= __get_user(npc, &sf->info.si_regs.npc);
103 
104 	if ((pc | npc) & 3)
105 		goto segv_and_exit;
106 
107 	/* 2. Restore the state */
108 	up_psr = regs->psr;
109 	err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
110 
111 	/* User can only change condition codes and FPU enabling in %psr. */
112 	regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
113 		  | (regs->psr & (PSR_ICC | PSR_EF));
114 
115 	/* Prevent syscall restart.  */
116 	pt_regs_clear_syscall(regs);
117 
118 	err |= __get_user(fpu_save, &sf->fpu_save);
119 	if (fpu_save)
120 		err |= restore_fpu_state(regs, fpu_save);
121 	err |= __get_user(rwin_save, &sf->rwin_save);
122 	if (rwin_save)
123 		err |= restore_rwin_state(rwin_save);
124 
125 	/* This is pretty much atomic, no amount locking would prevent
126 	 * the races which exist anyways.
127 	 */
128 	err |= __get_user(set.sig[0], &sf->info.si_mask);
129 	err |= __copy_from_user(&set.sig[1], &sf->extramask,
130 			        (_NSIG_WORDS-1) * sizeof(unsigned int));
131 
132 	if (err)
133 		goto segv_and_exit;
134 
135 	set_current_blocked(&set);
136 	return;
137 
138 segv_and_exit:
139 	force_sig(SIGSEGV);
140 }
141 
142 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
143 {
144 	struct rt_signal_frame __user *sf;
145 	unsigned int psr, pc, npc, ufp;
146 	__siginfo_fpu_t __user *fpu_save;
147 	__siginfo_rwin_t __user *rwin_save;
148 	sigset_t set;
149 	int err;
150 
151 	synchronize_user_stack();
152 	sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
153 	if (invalid_frame_pointer(sf, sizeof(*sf)))
154 		goto segv;
155 
156 	if (get_user(ufp, &sf->regs.u_regs[UREG_FP]))
157 		goto segv;
158 
159 	if (ufp & 0x7)
160 		goto segv;
161 
162 	err = __get_user(pc, &sf->regs.pc);
163 	err |= __get_user(npc, &sf->regs.npc);
164 	err |= ((pc | npc) & 0x03);
165 
166 	err |= __get_user(regs->y, &sf->regs.y);
167 	err |= __get_user(psr, &sf->regs.psr);
168 
169 	err |= __copy_from_user(&regs->u_regs[UREG_G1],
170 				&sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
171 
172 	regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
173 
174 	/* Prevent syscall restart.  */
175 	pt_regs_clear_syscall(regs);
176 
177 	err |= __get_user(fpu_save, &sf->fpu_save);
178 	if (!err && fpu_save)
179 		err |= restore_fpu_state(regs, fpu_save);
180 	err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
181 	err |= restore_altstack(&sf->stack);
182 
183 	if (err)
184 		goto segv;
185 
186 	regs->pc = pc;
187 	regs->npc = npc;
188 
189 	err |= __get_user(rwin_save, &sf->rwin_save);
190 	if (!err && rwin_save) {
191 		if (restore_rwin_state(rwin_save))
192 			goto segv;
193 	}
194 
195 	set_current_blocked(&set);
196 	return;
197 segv:
198 	force_sig(SIGSEGV);
199 }
200 
201 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
202 {
203 	unsigned long sp = regs->u_regs[UREG_FP];
204 
205 	/*
206 	 * If we are on the alternate signal stack and would overflow it, don't.
207 	 * Return an always-bogus address instead so we will die with SIGSEGV.
208 	 */
209 	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
210 		return (void __user *) -1L;
211 
212 	/* This is the X/Open sanctioned signal stack switching.  */
213 	sp = sigsp(sp, ksig) - framesize;
214 
215 	/* Always align the stack frame.  This handles two cases.  First,
216 	 * sigaltstack need not be mindful of platform specific stack
217 	 * alignment.  Second, if we took this signal because the stack
218 	 * is not aligned properly, we'd like to take the signal cleanly
219 	 * and report that.
220 	 */
221 	sp &= ~15UL;
222 
223 	return (void __user *) sp;
224 }
225 
226 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs,
227 		       sigset_t *oldset)
228 {
229 	struct signal_frame __user *sf;
230 	int sigframe_size, err, wsaved;
231 	void __user *tail;
232 
233 	/* 1. Make sure everything is clean */
234 	synchronize_user_stack();
235 
236 	wsaved = current_thread_info()->w_saved;
237 
238 	sigframe_size = sizeof(*sf);
239 	if (used_math())
240 		sigframe_size += sizeof(__siginfo_fpu_t);
241 	if (wsaved)
242 		sigframe_size += sizeof(__siginfo_rwin_t);
243 
244 	sf = (struct signal_frame __user *)
245 		get_sigframe(ksig, regs, sigframe_size);
246 
247 	if (invalid_frame_pointer(sf, sigframe_size)) {
248 		do_exit(SIGILL);
249 		return -EINVAL;
250 	}
251 
252 	tail = sf + 1;
253 
254 	/* 2. Save the current process state */
255 	err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
256 
257 	err |= __put_user(0, &sf->extra_size);
258 
259 	if (used_math()) {
260 		__siginfo_fpu_t __user *fp = tail;
261 		tail += sizeof(*fp);
262 		err |= save_fpu_state(regs, fp);
263 		err |= __put_user(fp, &sf->fpu_save);
264 	} else {
265 		err |= __put_user(0, &sf->fpu_save);
266 	}
267 	if (wsaved) {
268 		__siginfo_rwin_t __user *rwp = tail;
269 		tail += sizeof(*rwp);
270 		err |= save_rwin_state(wsaved, rwp);
271 		err |= __put_user(rwp, &sf->rwin_save);
272 	} else {
273 		err |= __put_user(0, &sf->rwin_save);
274 	}
275 
276 	err |= __put_user(oldset->sig[0], &sf->info.si_mask);
277 	err |= __copy_to_user(sf->extramask, &oldset->sig[1],
278 			      (_NSIG_WORDS - 1) * sizeof(unsigned int));
279 	if (!wsaved) {
280 		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
281 				      sizeof(struct reg_window32));
282 	} else {
283 		struct reg_window32 *rp;
284 
285 		rp = &current_thread_info()->reg_window[wsaved - 1];
286 		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
287 	}
288 	if (err)
289 		return err;
290 
291 	/* 3. signal handler back-trampoline and parameters */
292 	regs->u_regs[UREG_FP] = (unsigned long) sf;
293 	regs->u_regs[UREG_I0] = ksig->sig;
294 	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
295 	regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
296 
297 	/* 4. signal handler */
298 	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
299 	regs->npc = (regs->pc + 4);
300 
301 	/* 5. return to kernel instructions */
302 	if (ksig->ka.ka_restorer)
303 		regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
304 	else {
305 		regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
306 
307 		/* mov __NR_sigreturn, %g1 */
308 		err |= __put_user(0x821020d8, &sf->insns[0]);
309 
310 		/* t 0x10 */
311 		err |= __put_user(0x91d02010, &sf->insns[1]);
312 		if (err)
313 			return err;
314 
315 		/* Flush instruction space. */
316 		flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
317 	}
318 	return 0;
319 }
320 
321 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs,
322 			  sigset_t *oldset)
323 {
324 	struct rt_signal_frame __user *sf;
325 	int sigframe_size, wsaved;
326 	void __user *tail;
327 	unsigned int psr;
328 	int err;
329 
330 	synchronize_user_stack();
331 	wsaved = current_thread_info()->w_saved;
332 	sigframe_size = sizeof(*sf);
333 	if (used_math())
334 		sigframe_size += sizeof(__siginfo_fpu_t);
335 	if (wsaved)
336 		sigframe_size += sizeof(__siginfo_rwin_t);
337 	sf = (struct rt_signal_frame __user *)
338 		get_sigframe(ksig, regs, sigframe_size);
339 	if (invalid_frame_pointer(sf, sigframe_size)) {
340 		do_exit(SIGILL);
341 		return -EINVAL;
342 	}
343 
344 	tail = sf + 1;
345 	err  = __put_user(regs->pc, &sf->regs.pc);
346 	err |= __put_user(regs->npc, &sf->regs.npc);
347 	err |= __put_user(regs->y, &sf->regs.y);
348 	psr = regs->psr;
349 	if (used_math())
350 		psr |= PSR_EF;
351 	err |= __put_user(psr, &sf->regs.psr);
352 	err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
353 	err |= __put_user(0, &sf->extra_size);
354 
355 	if (psr & PSR_EF) {
356 		__siginfo_fpu_t __user *fp = tail;
357 		tail += sizeof(*fp);
358 		err |= save_fpu_state(regs, fp);
359 		err |= __put_user(fp, &sf->fpu_save);
360 	} else {
361 		err |= __put_user(0, &sf->fpu_save);
362 	}
363 	if (wsaved) {
364 		__siginfo_rwin_t __user *rwp = tail;
365 		tail += sizeof(*rwp);
366 		err |= save_rwin_state(wsaved, rwp);
367 		err |= __put_user(rwp, &sf->rwin_save);
368 	} else {
369 		err |= __put_user(0, &sf->rwin_save);
370 	}
371 	err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
372 
373 	/* Setup sigaltstack */
374 	err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
375 
376 	if (!wsaved) {
377 		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
378 				      sizeof(struct reg_window32));
379 	} else {
380 		struct reg_window32 *rp;
381 
382 		rp = &current_thread_info()->reg_window[wsaved - 1];
383 		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
384 	}
385 
386 	err |= copy_siginfo_to_user(&sf->info, &ksig->info);
387 
388 	if (err)
389 		return err;
390 
391 	regs->u_regs[UREG_FP] = (unsigned long) sf;
392 	regs->u_regs[UREG_I0] = ksig->sig;
393 	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
394 	regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
395 
396 	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
397 	regs->npc = (regs->pc + 4);
398 
399 	if (ksig->ka.ka_restorer)
400 		regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
401 	else {
402 		regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
403 
404 		/* mov __NR_sigreturn, %g1 */
405 		err |= __put_user(0x821020d8, &sf->insns[0]);
406 
407 		/* t 0x10 */
408 		err |= __put_user(0x91d02010, &sf->insns[1]);
409 		if (err)
410 			return err;
411 
412 		/* Flush instruction space. */
413 		flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
414 	}
415 	return 0;
416 }
417 
418 static inline void
419 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
420 {
421 	sigset_t *oldset = sigmask_to_save();
422 	int err;
423 
424 	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
425 		err = setup_rt_frame(ksig, regs, oldset);
426 	else
427 		err = setup_frame(ksig, regs, oldset);
428 	signal_setup_done(err, ksig, 0);
429 }
430 
431 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
432 				   struct sigaction *sa)
433 {
434 	switch(regs->u_regs[UREG_I0]) {
435 	case ERESTART_RESTARTBLOCK:
436 	case ERESTARTNOHAND:
437 	no_system_call_restart:
438 		regs->u_regs[UREG_I0] = EINTR;
439 		regs->psr |= PSR_C;
440 		break;
441 	case ERESTARTSYS:
442 		if (!(sa->sa_flags & SA_RESTART))
443 			goto no_system_call_restart;
444 		/* fallthrough */
445 	case ERESTARTNOINTR:
446 		regs->u_regs[UREG_I0] = orig_i0;
447 		regs->pc -= 4;
448 		regs->npc -= 4;
449 	}
450 }
451 
452 /* Note that 'init' is a special process: it doesn't get signals it doesn't
453  * want to handle. Thus you cannot kill init even with a SIGKILL even by
454  * mistake.
455  */
456 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
457 {
458 	struct ksignal ksig;
459 	int restart_syscall;
460 	bool has_handler;
461 
462 	/* It's a lot of work and synchronization to add a new ptrace
463 	 * register for GDB to save and restore in order to get
464 	 * orig_i0 correct for syscall restarts when debugging.
465 	 *
466 	 * Although it should be the case that most of the global
467 	 * registers are volatile across a system call, glibc already
468 	 * depends upon that fact that we preserve them.  So we can't
469 	 * just use any global register to save away the orig_i0 value.
470 	 *
471 	 * In particular %g2, %g3, %g4, and %g5 are all assumed to be
472 	 * preserved across a system call trap by various pieces of
473 	 * code in glibc.
474 	 *
475 	 * %g7 is used as the "thread register".   %g6 is not used in
476 	 * any fixed manner.  %g6 is used as a scratch register and
477 	 * a compiler temporary, but it's value is never used across
478 	 * a system call.  Therefore %g6 is usable for orig_i0 storage.
479 	 */
480 	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
481 		regs->u_regs[UREG_G6] = orig_i0;
482 
483 	has_handler = get_signal(&ksig);
484 
485 	/* If the debugger messes with the program counter, it clears
486 	 * the software "in syscall" bit, directing us to not perform
487 	 * a syscall restart.
488 	 */
489 	restart_syscall = 0;
490 	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
491 		restart_syscall = 1;
492 		orig_i0 = regs->u_regs[UREG_G6];
493 	}
494 
495 	if (has_handler) {
496 		if (restart_syscall)
497 			syscall_restart(orig_i0, regs, &ksig.ka.sa);
498 		handle_signal(&ksig, regs);
499 	} else {
500 		if (restart_syscall) {
501 			switch (regs->u_regs[UREG_I0]) {
502 			case ERESTARTNOHAND:
503 	     		case ERESTARTSYS:
504 			case ERESTARTNOINTR:
505 				/* replay the system call when we are done */
506 				regs->u_regs[UREG_I0] = orig_i0;
507 				regs->pc -= 4;
508 				regs->npc -= 4;
509 				pt_regs_clear_syscall(regs);
510 				/* fall through */
511 			case ERESTART_RESTARTBLOCK:
512 				regs->u_regs[UREG_G1] = __NR_restart_syscall;
513 				regs->pc -= 4;
514 				regs->npc -= 4;
515 				pt_regs_clear_syscall(regs);
516 			}
517 		}
518 		restore_saved_sigmask();
519 	}
520 }
521 
522 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
523 		      unsigned long thread_info_flags)
524 {
525 	if (thread_info_flags & _TIF_SIGPENDING)
526 		do_signal(regs, orig_i0);
527 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
528 		clear_thread_flag(TIF_NOTIFY_RESUME);
529 		tracehook_notify_resume(regs);
530 	}
531 }
532 
533 asmlinkage int do_sys_sigstack(struct sigstack __user *ssptr,
534                                struct sigstack __user *ossptr,
535                                unsigned long sp)
536 {
537 	int ret = -EFAULT;
538 
539 	/* First see if old state is wanted. */
540 	if (ossptr) {
541 		if (put_user(current->sas_ss_sp + current->sas_ss_size,
542 			     &ossptr->the_stack) ||
543 		    __put_user(on_sig_stack(sp), &ossptr->cur_status))
544 			goto out;
545 	}
546 
547 	/* Now see if we want to update the new state. */
548 	if (ssptr) {
549 		char *ss_sp;
550 
551 		if (get_user(ss_sp, &ssptr->the_stack))
552 			goto out;
553 		/* If the current stack was set with sigaltstack, don't
554 		   swap stacks while we are on it.  */
555 		ret = -EPERM;
556 		if (current->sas_ss_sp && on_sig_stack(sp))
557 			goto out;
558 
559 		/* Since we don't know the extent of the stack, and we don't
560 		   track onstack-ness, but rather calculate it, we must
561 		   presume a size.  Ho hum this interface is lossy.  */
562 		current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
563 		current->sas_ss_size = SIGSTKSZ;
564 	}
565 	ret = 0;
566 out:
567 	return ret;
568 }
569