xref: /openbmc/linux/arch/sparc/kernel/signal_32.c (revision b34e08d5)
1 /*  linux/arch/sparc/kernel/signal.c
2  *
3  *  Copyright (C) 1991, 1992  Linus Torvalds
4  *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
5  *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
6  *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
7  */
8 
9 #include <linux/sched.h>
10 #include <linux/kernel.h>
11 #include <linux/signal.h>
12 #include <linux/errno.h>
13 #include <linux/wait.h>
14 #include <linux/ptrace.h>
15 #include <linux/unistd.h>
16 #include <linux/mm.h>
17 #include <linux/tty.h>
18 #include <linux/smp.h>
19 #include <linux/binfmts.h>	/* do_coredum */
20 #include <linux/bitops.h>
21 #include <linux/tracehook.h>
22 
23 #include <asm/uaccess.h>
24 #include <asm/ptrace.h>
25 #include <asm/pgalloc.h>
26 #include <asm/pgtable.h>
27 #include <asm/cacheflush.h>	/* flush_sig_insns */
28 #include <asm/switch_to.h>
29 
30 #include "sigutil.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 asmlinkage void do_sigreturn(struct pt_regs *regs)
63 {
64 	struct signal_frame __user *sf;
65 	unsigned long up_psr, pc, npc;
66 	sigset_t set;
67 	__siginfo_fpu_t __user *fpu_save;
68 	__siginfo_rwin_t __user *rwin_save;
69 	int err;
70 
71 	/* Always make any pending restarted system calls return -EINTR */
72 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
73 
74 	synchronize_user_stack();
75 
76 	sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
77 
78 	/* 1. Make sure we are not getting garbage from the user */
79 	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
80 		goto segv_and_exit;
81 
82 	if (((unsigned long) sf) & 3)
83 		goto segv_and_exit;
84 
85 	err = __get_user(pc,  &sf->info.si_regs.pc);
86 	err |= __get_user(npc, &sf->info.si_regs.npc);
87 
88 	if ((pc | npc) & 3)
89 		goto segv_and_exit;
90 
91 	/* 2. Restore the state */
92 	up_psr = regs->psr;
93 	err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
94 
95 	/* User can only change condition codes and FPU enabling in %psr. */
96 	regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
97 		  | (regs->psr & (PSR_ICC | PSR_EF));
98 
99 	/* Prevent syscall restart.  */
100 	pt_regs_clear_syscall(regs);
101 
102 	err |= __get_user(fpu_save, &sf->fpu_save);
103 	if (fpu_save)
104 		err |= restore_fpu_state(regs, fpu_save);
105 	err |= __get_user(rwin_save, &sf->rwin_save);
106 	if (rwin_save)
107 		err |= restore_rwin_state(rwin_save);
108 
109 	/* This is pretty much atomic, no amount locking would prevent
110 	 * the races which exist anyways.
111 	 */
112 	err |= __get_user(set.sig[0], &sf->info.si_mask);
113 	err |= __copy_from_user(&set.sig[1], &sf->extramask,
114 			        (_NSIG_WORDS-1) * sizeof(unsigned int));
115 
116 	if (err)
117 		goto segv_and_exit;
118 
119 	set_current_blocked(&set);
120 	return;
121 
122 segv_and_exit:
123 	force_sig(SIGSEGV, current);
124 }
125 
126 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
127 {
128 	struct rt_signal_frame __user *sf;
129 	unsigned int psr, pc, npc;
130 	__siginfo_fpu_t __user *fpu_save;
131 	__siginfo_rwin_t __user *rwin_save;
132 	sigset_t set;
133 	int err;
134 
135 	synchronize_user_stack();
136 	sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
137 	if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
138 	    (((unsigned long) sf) & 0x03))
139 		goto segv;
140 
141 	err = __get_user(pc, &sf->regs.pc);
142 	err |= __get_user(npc, &sf->regs.npc);
143 	err |= ((pc | npc) & 0x03);
144 
145 	err |= __get_user(regs->y, &sf->regs.y);
146 	err |= __get_user(psr, &sf->regs.psr);
147 
148 	err |= __copy_from_user(&regs->u_regs[UREG_G1],
149 				&sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
150 
151 	regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
152 
153 	/* Prevent syscall restart.  */
154 	pt_regs_clear_syscall(regs);
155 
156 	err |= __get_user(fpu_save, &sf->fpu_save);
157 	if (!err && fpu_save)
158 		err |= restore_fpu_state(regs, fpu_save);
159 	err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
160 	err |= restore_altstack(&sf->stack);
161 
162 	if (err)
163 		goto segv;
164 
165 	regs->pc = pc;
166 	regs->npc = npc;
167 
168 	err |= __get_user(rwin_save, &sf->rwin_save);
169 	if (!err && rwin_save) {
170 		if (restore_rwin_state(rwin_save))
171 			goto segv;
172 	}
173 
174 	set_current_blocked(&set);
175 	return;
176 segv:
177 	force_sig(SIGSEGV, current);
178 }
179 
180 /* Checks if the fp is valid */
181 static inline int invalid_frame_pointer(void __user *fp, int fplen)
182 {
183 	if ((((unsigned long) fp) & 7) || !__access_ok((unsigned long)fp, fplen))
184 		return 1;
185 
186 	return 0;
187 }
188 
189 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
190 {
191 	unsigned long sp = regs->u_regs[UREG_FP];
192 
193 	/*
194 	 * If we are on the alternate signal stack and would overflow it, don't.
195 	 * Return an always-bogus address instead so we will die with SIGSEGV.
196 	 */
197 	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
198 		return (void __user *) -1L;
199 
200 	/* This is the X/Open sanctioned signal stack switching.  */
201 	sp = sigsp(sp, ksig) - framesize;
202 
203 	/* Always align the stack frame.  This handles two cases.  First,
204 	 * sigaltstack need not be mindful of platform specific stack
205 	 * alignment.  Second, if we took this signal because the stack
206 	 * is not aligned properly, we'd like to take the signal cleanly
207 	 * and report that.
208 	 */
209 	sp &= ~15UL;
210 
211 	return (void __user *) sp;
212 }
213 
214 static int setup_frame(struct ksignal *ksig, struct pt_regs *regs,
215 		       sigset_t *oldset)
216 {
217 	struct signal_frame __user *sf;
218 	int sigframe_size, err, wsaved;
219 	void __user *tail;
220 
221 	/* 1. Make sure everything is clean */
222 	synchronize_user_stack();
223 
224 	wsaved = current_thread_info()->w_saved;
225 
226 	sigframe_size = sizeof(*sf);
227 	if (used_math())
228 		sigframe_size += sizeof(__siginfo_fpu_t);
229 	if (wsaved)
230 		sigframe_size += sizeof(__siginfo_rwin_t);
231 
232 	sf = (struct signal_frame __user *)
233 		get_sigframe(ksig, regs, sigframe_size);
234 
235 	if (invalid_frame_pointer(sf, sigframe_size)) {
236 		do_exit(SIGILL);
237 		return -EINVAL;
238 	}
239 
240 	tail = sf + 1;
241 
242 	/* 2. Save the current process state */
243 	err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
244 
245 	err |= __put_user(0, &sf->extra_size);
246 
247 	if (used_math()) {
248 		__siginfo_fpu_t __user *fp = tail;
249 		tail += sizeof(*fp);
250 		err |= save_fpu_state(regs, fp);
251 		err |= __put_user(fp, &sf->fpu_save);
252 	} else {
253 		err |= __put_user(0, &sf->fpu_save);
254 	}
255 	if (wsaved) {
256 		__siginfo_rwin_t __user *rwp = tail;
257 		tail += sizeof(*rwp);
258 		err |= save_rwin_state(wsaved, rwp);
259 		err |= __put_user(rwp, &sf->rwin_save);
260 	} else {
261 		err |= __put_user(0, &sf->rwin_save);
262 	}
263 
264 	err |= __put_user(oldset->sig[0], &sf->info.si_mask);
265 	err |= __copy_to_user(sf->extramask, &oldset->sig[1],
266 			      (_NSIG_WORDS - 1) * sizeof(unsigned int));
267 	if (!wsaved) {
268 		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
269 				      sizeof(struct reg_window32));
270 	} else {
271 		struct reg_window32 *rp;
272 
273 		rp = &current_thread_info()->reg_window[wsaved - 1];
274 		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
275 	}
276 	if (err)
277 		return err;
278 
279 	/* 3. signal handler back-trampoline and parameters */
280 	regs->u_regs[UREG_FP] = (unsigned long) sf;
281 	regs->u_regs[UREG_I0] = ksig->sig;
282 	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
283 	regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
284 
285 	/* 4. signal handler */
286 	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
287 	regs->npc = (regs->pc + 4);
288 
289 	/* 5. return to kernel instructions */
290 	if (ksig->ka.ka_restorer)
291 		regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
292 	else {
293 		regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
294 
295 		/* mov __NR_sigreturn, %g1 */
296 		err |= __put_user(0x821020d8, &sf->insns[0]);
297 
298 		/* t 0x10 */
299 		err |= __put_user(0x91d02010, &sf->insns[1]);
300 		if (err)
301 			return err;
302 
303 		/* Flush instruction space. */
304 		flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
305 	}
306 	return 0;
307 }
308 
309 static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs,
310 			  sigset_t *oldset)
311 {
312 	struct rt_signal_frame __user *sf;
313 	int sigframe_size, wsaved;
314 	void __user *tail;
315 	unsigned int psr;
316 	int err;
317 
318 	synchronize_user_stack();
319 	wsaved = current_thread_info()->w_saved;
320 	sigframe_size = sizeof(*sf);
321 	if (used_math())
322 		sigframe_size += sizeof(__siginfo_fpu_t);
323 	if (wsaved)
324 		sigframe_size += sizeof(__siginfo_rwin_t);
325 	sf = (struct rt_signal_frame __user *)
326 		get_sigframe(ksig, regs, sigframe_size);
327 	if (invalid_frame_pointer(sf, sigframe_size)) {
328 		do_exit(SIGILL);
329 		return -EINVAL;
330 	}
331 
332 	tail = sf + 1;
333 	err  = __put_user(regs->pc, &sf->regs.pc);
334 	err |= __put_user(regs->npc, &sf->regs.npc);
335 	err |= __put_user(regs->y, &sf->regs.y);
336 	psr = regs->psr;
337 	if (used_math())
338 		psr |= PSR_EF;
339 	err |= __put_user(psr, &sf->regs.psr);
340 	err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
341 	err |= __put_user(0, &sf->extra_size);
342 
343 	if (psr & PSR_EF) {
344 		__siginfo_fpu_t *fp = tail;
345 		tail += sizeof(*fp);
346 		err |= save_fpu_state(regs, fp);
347 		err |= __put_user(fp, &sf->fpu_save);
348 	} else {
349 		err |= __put_user(0, &sf->fpu_save);
350 	}
351 	if (wsaved) {
352 		__siginfo_rwin_t *rwp = tail;
353 		tail += sizeof(*rwp);
354 		err |= save_rwin_state(wsaved, rwp);
355 		err |= __put_user(rwp, &sf->rwin_save);
356 	} else {
357 		err |= __put_user(0, &sf->rwin_save);
358 	}
359 	err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
360 
361 	/* Setup sigaltstack */
362 	err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
363 
364 	if (!wsaved) {
365 		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
366 				      sizeof(struct reg_window32));
367 	} else {
368 		struct reg_window32 *rp;
369 
370 		rp = &current_thread_info()->reg_window[wsaved - 1];
371 		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
372 	}
373 
374 	err |= copy_siginfo_to_user(&sf->info, &ksig->info);
375 
376 	if (err)
377 		return err;
378 
379 	regs->u_regs[UREG_FP] = (unsigned long) sf;
380 	regs->u_regs[UREG_I0] = ksig->sig;
381 	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
382 	regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
383 
384 	regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
385 	regs->npc = (regs->pc + 4);
386 
387 	if (ksig->ka.ka_restorer)
388 		regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
389 	else {
390 		regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
391 
392 		/* mov __NR_sigreturn, %g1 */
393 		err |= __put_user(0x821020d8, &sf->insns[0]);
394 
395 		/* t 0x10 */
396 		err |= __put_user(0x91d02010, &sf->insns[1]);
397 		if (err)
398 			return err;
399 
400 		/* Flush instruction space. */
401 		flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
402 	}
403 	return 0;
404 }
405 
406 static inline void
407 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
408 {
409 	sigset_t *oldset = sigmask_to_save();
410 	int err;
411 
412 	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
413 		err = setup_rt_frame(ksig, regs, oldset);
414 	else
415 		err = setup_frame(ksig, regs, oldset);
416 	signal_setup_done(err, ksig, 0);
417 }
418 
419 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
420 				   struct sigaction *sa)
421 {
422 	switch(regs->u_regs[UREG_I0]) {
423 	case ERESTART_RESTARTBLOCK:
424 	case ERESTARTNOHAND:
425 	no_system_call_restart:
426 		regs->u_regs[UREG_I0] = EINTR;
427 		regs->psr |= PSR_C;
428 		break;
429 	case ERESTARTSYS:
430 		if (!(sa->sa_flags & SA_RESTART))
431 			goto no_system_call_restart;
432 		/* fallthrough */
433 	case ERESTARTNOINTR:
434 		regs->u_regs[UREG_I0] = orig_i0;
435 		regs->pc -= 4;
436 		regs->npc -= 4;
437 	}
438 }
439 
440 /* Note that 'init' is a special process: it doesn't get signals it doesn't
441  * want to handle. Thus you cannot kill init even with a SIGKILL even by
442  * mistake.
443  */
444 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
445 {
446 	struct ksignal ksig;
447 	int restart_syscall;
448 	bool has_handler;
449 
450 	/* It's a lot of work and synchronization to add a new ptrace
451 	 * register for GDB to save and restore in order to get
452 	 * orig_i0 correct for syscall restarts when debugging.
453 	 *
454 	 * Although it should be the case that most of the global
455 	 * registers are volatile across a system call, glibc already
456 	 * depends upon that fact that we preserve them.  So we can't
457 	 * just use any global register to save away the orig_i0 value.
458 	 *
459 	 * In particular %g2, %g3, %g4, and %g5 are all assumed to be
460 	 * preserved across a system call trap by various pieces of
461 	 * code in glibc.
462 	 *
463 	 * %g7 is used as the "thread register".   %g6 is not used in
464 	 * any fixed manner.  %g6 is used as a scratch register and
465 	 * a compiler temporary, but it's value is never used across
466 	 * a system call.  Therefore %g6 is usable for orig_i0 storage.
467 	 */
468 	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
469 		regs->u_regs[UREG_G6] = orig_i0;
470 
471 	has_handler = get_signal(&ksig);
472 
473 	/* If the debugger messes with the program counter, it clears
474 	 * the software "in syscall" bit, directing us to not perform
475 	 * a syscall restart.
476 	 */
477 	restart_syscall = 0;
478 	if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
479 		restart_syscall = 1;
480 		orig_i0 = regs->u_regs[UREG_G6];
481 	}
482 
483 	if (has_handler) {
484 		if (restart_syscall)
485 			syscall_restart(orig_i0, regs, &ksig.ka.sa);
486 		handle_signal(&ksig, regs);
487 	} else {
488 		if (restart_syscall) {
489 			switch (regs->u_regs[UREG_I0]) {
490 			case ERESTARTNOHAND:
491 	     		case ERESTARTSYS:
492 			case ERESTARTNOINTR:
493 				/* replay the system call when we are done */
494 				regs->u_regs[UREG_I0] = orig_i0;
495 				regs->pc -= 4;
496 				regs->npc -= 4;
497 				pt_regs_clear_syscall(regs);
498 			case ERESTART_RESTARTBLOCK:
499 				regs->u_regs[UREG_G1] = __NR_restart_syscall;
500 				regs->pc -= 4;
501 				regs->npc -= 4;
502 				pt_regs_clear_syscall(regs);
503 			}
504 		}
505 		restore_saved_sigmask();
506 	}
507 }
508 
509 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
510 		      unsigned long thread_info_flags)
511 {
512 	if (thread_info_flags & _TIF_SIGPENDING)
513 		do_signal(regs, orig_i0);
514 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
515 		clear_thread_flag(TIF_NOTIFY_RESUME);
516 		tracehook_notify_resume(regs);
517 	}
518 }
519 
520 asmlinkage int
521 do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
522 		unsigned long sp)
523 {
524 	int ret = -EFAULT;
525 
526 	/* First see if old state is wanted. */
527 	if (ossptr) {
528 		if (put_user(current->sas_ss_sp + current->sas_ss_size,
529 			     &ossptr->the_stack) ||
530 		    __put_user(on_sig_stack(sp), &ossptr->cur_status))
531 			goto out;
532 	}
533 
534 	/* Now see if we want to update the new state. */
535 	if (ssptr) {
536 		char *ss_sp;
537 
538 		if (get_user(ss_sp, &ssptr->the_stack))
539 			goto out;
540 		/* If the current stack was set with sigaltstack, don't
541 		   swap stacks while we are on it.  */
542 		ret = -EPERM;
543 		if (current->sas_ss_sp && on_sig_stack(sp))
544 			goto out;
545 
546 		/* Since we don't know the extent of the stack, and we don't
547 		   track onstack-ness, but rather calculate it, we must
548 		   presume a size.  Ho hum this interface is lossy.  */
549 		current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
550 		current->sas_ss_size = SIGSTKSZ;
551 	}
552 	ret = 0;
553 out:
554 	return ret;
555 }
556