xref: /linux/arch/sh/kernel/signal_32.c (revision 95e9fd10f06cb5642028b6b851e32b8c8afb4571)
1 /*
2  *  linux/arch/sh/kernel/signal.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
6  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
7  *
8  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
9  *
10  */
11 #include <linux/sched.h>
12 #include <linux/mm.h>
13 #include <linux/smp.h>
14 #include <linux/kernel.h>
15 #include <linux/signal.h>
16 #include <linux/errno.h>
17 #include <linux/wait.h>
18 #include <linux/ptrace.h>
19 #include <linux/unistd.h>
20 #include <linux/stddef.h>
21 #include <linux/tty.h>
22 #include <linux/elf.h>
23 #include <linux/personality.h>
24 #include <linux/binfmts.h>
25 #include <linux/freezer.h>
26 #include <linux/io.h>
27 #include <linux/tracehook.h>
28 #include <asm/ucontext.h>
29 #include <asm/uaccess.h>
30 #include <asm/pgtable.h>
31 #include <asm/cacheflush.h>
32 #include <asm/syscalls.h>
33 #include <asm/fpu.h>
34 
35 struct fdpic_func_descriptor {
36 	unsigned long	text;
37 	unsigned long	GOT;
38 };
39 
40 /*
41  * The following define adds a 64 byte gap between the signal
42  * stack frame and previous contents of the stack.  This allows
43  * frame unwinding in a function epilogue but only if a frame
44  * pointer is used in the function.  This is necessary because
45  * current gcc compilers (<4.3) do not generate unwind info on
46  * SH for function epilogues.
47  */
48 #define UNWINDGUARD 64
49 
50 /*
51  * Atomically swap in the new signal mask, and wait for a signal.
52  */
53 asmlinkage int
54 sys_sigsuspend(old_sigset_t mask)
55 {
56 	sigset_t blocked;
57 	siginitset(&blocked, mask);
58 	return sigsuspend(&blocked);
59 }
60 
61 asmlinkage int
62 sys_sigaction(int sig, const struct old_sigaction __user *act,
63 	      struct old_sigaction __user *oact)
64 {
65 	struct k_sigaction new_ka, old_ka;
66 	int ret;
67 
68 	if (act) {
69 		old_sigset_t mask;
70 		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
71 		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
72 		    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
73 		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
74 		    __get_user(mask, &act->sa_mask))
75 			return -EFAULT;
76 		siginitset(&new_ka.sa.sa_mask, mask);
77 	}
78 
79 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
80 
81 	if (!ret && oact) {
82 		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
83 		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
84 		    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
85 		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
86 		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
87 			return -EFAULT;
88 	}
89 
90 	return ret;
91 }
92 
93 asmlinkage int
94 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
95 		unsigned long r6, unsigned long r7,
96 		struct pt_regs __regs)
97 {
98 	struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
99 
100 	return do_sigaltstack(uss, uoss, regs->regs[15]);
101 }
102 
103 
104 /*
105  * Do a signal return; undo the signal stack.
106  */
107 
108 #define MOVW(n)	 (0x9300|((n)-2))	/* Move mem word at PC+n to R3 */
109 #if defined(CONFIG_CPU_SH2)
110 #define TRAP_NOARG 0xc320		/* Syscall w/no args (NR in R3) */
111 #else
112 #define TRAP_NOARG 0xc310		/* Syscall w/no args (NR in R3) */
113 #endif
114 #define OR_R0_R0 0x200b			/* or r0,r0 (insert to avoid hardware bug) */
115 
116 struct sigframe
117 {
118 	struct sigcontext sc;
119 	unsigned long extramask[_NSIG_WORDS-1];
120 	u16 retcode[8];
121 };
122 
123 struct rt_sigframe
124 {
125 	struct siginfo info;
126 	struct ucontext uc;
127 	u16 retcode[8];
128 };
129 
130 #ifdef CONFIG_SH_FPU
131 static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
132 {
133 	struct task_struct *tsk = current;
134 
135 	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
136 		return 0;
137 
138 	set_used_math();
139 	return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
140 				sizeof(long)*(16*2+2));
141 }
142 
143 static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
144 				      struct pt_regs *regs)
145 {
146 	struct task_struct *tsk = current;
147 
148 	if (!(boot_cpu_data.flags & CPU_HAS_FPU))
149 		return 0;
150 
151 	if (!used_math())
152 		return __put_user(0, &sc->sc_ownedfp);
153 
154 	if (__put_user(1, &sc->sc_ownedfp))
155 		return -EFAULT;
156 
157 	/* This will cause a "finit" to be triggered by the next
158 	   attempted FPU operation by the 'current' process.
159 	   */
160 	clear_used_math();
161 
162 	unlazy_fpu(tsk, regs);
163 	return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
164 			      sizeof(long)*(16*2+2));
165 }
166 #endif /* CONFIG_SH_FPU */
167 
168 static int
169 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
170 {
171 	unsigned int err = 0;
172 
173 #define COPY(x)		err |= __get_user(regs->x, &sc->sc_##x)
174 			COPY(regs[1]);
175 	COPY(regs[2]);	COPY(regs[3]);
176 	COPY(regs[4]);	COPY(regs[5]);
177 	COPY(regs[6]);	COPY(regs[7]);
178 	COPY(regs[8]);	COPY(regs[9]);
179 	COPY(regs[10]);	COPY(regs[11]);
180 	COPY(regs[12]);	COPY(regs[13]);
181 	COPY(regs[14]);	COPY(regs[15]);
182 	COPY(gbr);	COPY(mach);
183 	COPY(macl);	COPY(pr);
184 	COPY(sr);	COPY(pc);
185 #undef COPY
186 
187 #ifdef CONFIG_SH_FPU
188 	if (boot_cpu_data.flags & CPU_HAS_FPU) {
189 		int owned_fp;
190 		struct task_struct *tsk = current;
191 
192 		regs->sr |= SR_FD; /* Release FPU */
193 		clear_fpu(tsk, regs);
194 		clear_used_math();
195 		err |= __get_user (owned_fp, &sc->sc_ownedfp);
196 		if (owned_fp)
197 			err |= restore_sigcontext_fpu(sc);
198 	}
199 #endif
200 
201 	regs->tra = -1;		/* disable syscall checks */
202 	err |= __get_user(*r0_p, &sc->sc_regs[0]);
203 	return err;
204 }
205 
206 asmlinkage int sys_sigreturn(unsigned long r4, unsigned long r5,
207 			     unsigned long r6, unsigned long r7,
208 			     struct pt_regs __regs)
209 {
210 	struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
211 	struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
212 	sigset_t set;
213 	int r0;
214 
215         /* Always make any pending restarted system calls return -EINTR */
216 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
217 
218 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
219 		goto badframe;
220 
221 	if (__get_user(set.sig[0], &frame->sc.oldmask)
222 	    || (_NSIG_WORDS > 1
223 		&& __copy_from_user(&set.sig[1], &frame->extramask,
224 				    sizeof(frame->extramask))))
225 		goto badframe;
226 
227 	set_current_blocked(&set);
228 
229 	if (restore_sigcontext(regs, &frame->sc, &r0))
230 		goto badframe;
231 	return r0;
232 
233 badframe:
234 	force_sig(SIGSEGV, current);
235 	return 0;
236 }
237 
238 asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
239 				unsigned long r6, unsigned long r7,
240 				struct pt_regs __regs)
241 {
242 	struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
243 	struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
244 	sigset_t set;
245 	int r0;
246 
247 	/* Always make any pending restarted system calls return -EINTR */
248 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
249 
250 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
251 		goto badframe;
252 
253 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
254 		goto badframe;
255 
256 	set_current_blocked(&set);
257 
258 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
259 		goto badframe;
260 
261 	if (do_sigaltstack(&frame->uc.uc_stack, NULL,
262 			   regs->regs[15]) == -EFAULT)
263 		goto badframe;
264 
265 	return r0;
266 
267 badframe:
268 	force_sig(SIGSEGV, current);
269 	return 0;
270 }
271 
272 /*
273  * Set up a signal frame.
274  */
275 
276 static int
277 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
278 		 unsigned long mask)
279 {
280 	int err = 0;
281 
282 #define COPY(x)		err |= __put_user(regs->x, &sc->sc_##x)
283 	COPY(regs[0]);	COPY(regs[1]);
284 	COPY(regs[2]);	COPY(regs[3]);
285 	COPY(regs[4]);	COPY(regs[5]);
286 	COPY(regs[6]);	COPY(regs[7]);
287 	COPY(regs[8]);	COPY(regs[9]);
288 	COPY(regs[10]);	COPY(regs[11]);
289 	COPY(regs[12]);	COPY(regs[13]);
290 	COPY(regs[14]);	COPY(regs[15]);
291 	COPY(gbr);	COPY(mach);
292 	COPY(macl);	COPY(pr);
293 	COPY(sr);	COPY(pc);
294 #undef COPY
295 
296 #ifdef CONFIG_SH_FPU
297 	err |= save_sigcontext_fpu(sc, regs);
298 #endif
299 
300 	/* non-iBCS2 extensions.. */
301 	err |= __put_user(mask, &sc->oldmask);
302 
303 	return err;
304 }
305 
306 /*
307  * Determine which stack to use..
308  */
309 static inline void __user *
310 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
311 {
312 	if (ka->sa.sa_flags & SA_ONSTACK) {
313 		if (sas_ss_flags(sp) == 0)
314 			sp = current->sas_ss_sp + current->sas_ss_size;
315 	}
316 
317 	return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
318 }
319 
320 /* These symbols are defined with the addresses in the vsyscall page.
321    See vsyscall-trapa.S.  */
322 extern void __kernel_sigreturn(void);
323 extern void __kernel_rt_sigreturn(void);
324 
325 static int setup_frame(int sig, struct k_sigaction *ka,
326 			sigset_t *set, struct pt_regs *regs)
327 {
328 	struct sigframe __user *frame;
329 	int err = 0;
330 	int signal;
331 
332 	frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
333 
334 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
335 		goto give_sigsegv;
336 
337 	signal = current_thread_info()->exec_domain
338 		&& current_thread_info()->exec_domain->signal_invmap
339 		&& sig < 32
340 		? current_thread_info()->exec_domain->signal_invmap[sig]
341 		: sig;
342 
343 	err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
344 
345 	if (_NSIG_WORDS > 1)
346 		err |= __copy_to_user(frame->extramask, &set->sig[1],
347 				      sizeof(frame->extramask));
348 
349 	/* Set up to return from userspace.  If provided, use a stub
350 	   already in userspace.  */
351 	if (ka->sa.sa_flags & SA_RESTORER) {
352 		regs->pr = (unsigned long) ka->sa.sa_restorer;
353 #ifdef CONFIG_VSYSCALL
354 	} else if (likely(current->mm->context.vdso)) {
355 		regs->pr = VDSO_SYM(&__kernel_sigreturn);
356 #endif
357 	} else {
358 		/* Generate return code (system call to sigreturn) */
359 		err |= __put_user(MOVW(7), &frame->retcode[0]);
360 		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
361 		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
362 		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
363 		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
364 		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
365 		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
366 		err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
367 		regs->pr = (unsigned long) frame->retcode;
368 		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
369 	}
370 
371 	if (err)
372 		goto give_sigsegv;
373 
374 	/* Set up registers for signal handler */
375 	regs->regs[15] = (unsigned long) frame;
376 	regs->regs[4] = signal; /* Arg for signal handler */
377 	regs->regs[5] = 0;
378 	regs->regs[6] = (unsigned long) &frame->sc;
379 
380 	if (current->personality & FDPIC_FUNCPTRS) {
381 		struct fdpic_func_descriptor __user *funcptr =
382 			(struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
383 
384 		err |= __get_user(regs->pc, &funcptr->text);
385 		err |= __get_user(regs->regs[12], &funcptr->GOT);
386 	} else
387 		regs->pc = (unsigned long)ka->sa.sa_handler;
388 
389 	if (err)
390 		goto give_sigsegv;
391 
392 	set_fs(USER_DS);
393 
394 	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
395 		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
396 
397 	return 0;
398 
399 give_sigsegv:
400 	force_sigsegv(sig, current);
401 	return -EFAULT;
402 }
403 
404 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
405 			   sigset_t *set, struct pt_regs *regs)
406 {
407 	struct rt_sigframe __user *frame;
408 	int err = 0;
409 	int signal;
410 
411 	frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
412 
413 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
414 		goto give_sigsegv;
415 
416 	signal = current_thread_info()->exec_domain
417 		&& current_thread_info()->exec_domain->signal_invmap
418 		&& sig < 32
419 		? current_thread_info()->exec_domain->signal_invmap[sig]
420 		: sig;
421 
422 	err |= copy_siginfo_to_user(&frame->info, info);
423 
424 	/* Create the ucontext.  */
425 	err |= __put_user(0, &frame->uc.uc_flags);
426 	err |= __put_user(NULL, &frame->uc.uc_link);
427 	err |= __put_user((void *)current->sas_ss_sp,
428 			  &frame->uc.uc_stack.ss_sp);
429 	err |= __put_user(sas_ss_flags(regs->regs[15]),
430 			  &frame->uc.uc_stack.ss_flags);
431 	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
432 	err |= setup_sigcontext(&frame->uc.uc_mcontext,
433 			        regs, set->sig[0]);
434 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
435 
436 	/* Set up to return from userspace.  If provided, use a stub
437 	   already in userspace.  */
438 	if (ka->sa.sa_flags & SA_RESTORER) {
439 		regs->pr = (unsigned long) ka->sa.sa_restorer;
440 #ifdef CONFIG_VSYSCALL
441 	} else if (likely(current->mm->context.vdso)) {
442 		regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
443 #endif
444 	} else {
445 		/* Generate return code (system call to rt_sigreturn) */
446 		err |= __put_user(MOVW(7), &frame->retcode[0]);
447 		err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
448 		err |= __put_user(OR_R0_R0, &frame->retcode[2]);
449 		err |= __put_user(OR_R0_R0, &frame->retcode[3]);
450 		err |= __put_user(OR_R0_R0, &frame->retcode[4]);
451 		err |= __put_user(OR_R0_R0, &frame->retcode[5]);
452 		err |= __put_user(OR_R0_R0, &frame->retcode[6]);
453 		err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
454 		regs->pr = (unsigned long) frame->retcode;
455 		flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
456 	}
457 
458 	if (err)
459 		goto give_sigsegv;
460 
461 	/* Set up registers for signal handler */
462 	regs->regs[15] = (unsigned long) frame;
463 	regs->regs[4] = signal; /* Arg for signal handler */
464 	regs->regs[5] = (unsigned long) &frame->info;
465 	regs->regs[6] = (unsigned long) &frame->uc;
466 
467 	if (current->personality & FDPIC_FUNCPTRS) {
468 		struct fdpic_func_descriptor __user *funcptr =
469 			(struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
470 
471 		err |= __get_user(regs->pc, &funcptr->text);
472 		err |= __get_user(regs->regs[12], &funcptr->GOT);
473 	} else
474 		regs->pc = (unsigned long)ka->sa.sa_handler;
475 
476 	if (err)
477 		goto give_sigsegv;
478 
479 	set_fs(USER_DS);
480 
481 	pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
482 		 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
483 
484 	return 0;
485 
486 give_sigsegv:
487 	force_sigsegv(sig, current);
488 	return -EFAULT;
489 }
490 
491 static inline void
492 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
493 		       struct sigaction *sa)
494 {
495 	/* If we're not from a syscall, bail out */
496 	if (regs->tra < 0)
497 		return;
498 
499 	/* check for system call restart.. */
500 	switch (regs->regs[0]) {
501 		case -ERESTART_RESTARTBLOCK:
502 		case -ERESTARTNOHAND:
503 		no_system_call_restart:
504 			regs->regs[0] = -EINTR;
505 			break;
506 
507 		case -ERESTARTSYS:
508 			if (!(sa->sa_flags & SA_RESTART))
509 				goto no_system_call_restart;
510 		/* fallthrough */
511 		case -ERESTARTNOINTR:
512 			regs->regs[0] = save_r0;
513 			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
514 			break;
515 	}
516 }
517 
518 /*
519  * OK, we're invoking a handler
520  */
521 static void
522 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
523 	      struct pt_regs *regs, unsigned int save_r0)
524 {
525 	sigset_t *oldset = sigmask_to_save();
526 	int ret;
527 
528 	/* Set up the stack frame */
529 	if (ka->sa.sa_flags & SA_SIGINFO)
530 		ret = setup_rt_frame(sig, ka, info, oldset, regs);
531 	else
532 		ret = setup_frame(sig, ka, oldset, regs);
533 
534 	if (ret)
535 		return;
536 	signal_delivered(sig, info, ka, regs,
537 			test_thread_flag(TIF_SINGLESTEP));
538 }
539 
540 /*
541  * Note that 'init' is a special process: it doesn't get signals it doesn't
542  * want to handle. Thus you cannot kill init even with a SIGKILL even by
543  * mistake.
544  *
545  * Note that we go through the signals twice: once to check the signals that
546  * the kernel can handle, and then we build all the user-level signal handling
547  * stack-frames in one go after that.
548  */
549 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
550 {
551 	siginfo_t info;
552 	int signr;
553 	struct k_sigaction ka;
554 
555 	/*
556 	 * We want the common case to go fast, which
557 	 * is why we may in certain cases get here from
558 	 * kernel mode. Just return without doing anything
559 	 * if so.
560 	 */
561 	if (!user_mode(regs))
562 		return;
563 
564 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
565 	if (signr > 0) {
566 		handle_syscall_restart(save_r0, regs, &ka.sa);
567 
568 		/* Whee!  Actually deliver the signal.  */
569 		handle_signal(signr, &ka, &info, regs, save_r0);
570 		return;
571 	}
572 
573 	/* Did we come from a system call? */
574 	if (regs->tra >= 0) {
575 		/* Restart the system call - no handlers present */
576 		if (regs->regs[0] == -ERESTARTNOHAND ||
577 		    regs->regs[0] == -ERESTARTSYS ||
578 		    regs->regs[0] == -ERESTARTNOINTR) {
579 			regs->regs[0] = save_r0;
580 			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
581 		} else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
582 			regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
583 			regs->regs[3] = __NR_restart_syscall;
584 		}
585 	}
586 
587 	/*
588 	 * If there's no signal to deliver, we just put the saved sigmask
589 	 * back.
590 	 */
591 	restore_saved_sigmask();
592 }
593 
594 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
595 				 unsigned long thread_info_flags)
596 {
597 	/* deal with pending signal delivery */
598 	if (thread_info_flags & _TIF_SIGPENDING)
599 		do_signal(regs, save_r0);
600 
601 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
602 		clear_thread_flag(TIF_NOTIFY_RESUME);
603 		tracehook_notify_resume(regs);
604 	}
605 }
606