1/*
2 *  linux/arch/alpha/kernel/signal.c
3 *
4 *  Copyright (C) 1995  Linus Torvalds
5 *
6 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
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/smp.h>
18#include <linux/stddef.h>
19#include <linux/tty.h>
20#include <linux/binfmts.h>
21#include <linux/bitops.h>
22#include <linux/syscalls.h>
23#include <linux/tracehook.h>
24
25#include <asm/uaccess.h>
26#include <asm/sigcontext.h>
27#include <asm/ucontext.h>
28
29#include "proto.h"
30
31
32#define DEBUG_SIG 0
33
34#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
35
36asmlinkage void ret_from_sys_call(void);
37
38/*
39 * The OSF/1 sigprocmask calling sequence is different from the
40 * C sigprocmask() sequence..
41 */
42SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
43{
44	sigset_t oldmask;
45	sigset_t mask;
46	unsigned long res;
47
48	siginitset(&mask, newmask & _BLOCKABLE);
49	res = sigprocmask(how, &mask, &oldmask);
50	if (!res) {
51		force_successful_syscall_return();
52		res = oldmask.sig[0];
53	}
54	return res;
55}
56
57SYSCALL_DEFINE3(osf_sigaction, int, sig,
58		const struct osf_sigaction __user *, act,
59		struct osf_sigaction __user *, oact)
60{
61	struct k_sigaction new_ka, old_ka;
62	int ret;
63
64	if (act) {
65		old_sigset_t mask;
66		if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
67		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
68		    __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
69		    __get_user(mask, &act->sa_mask))
70			return -EFAULT;
71		siginitset(&new_ka.sa.sa_mask, mask);
72		new_ka.ka_restorer = NULL;
73	}
74
75	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
76
77	if (!ret && oact) {
78		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
79		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
80		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
81		    __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
82			return -EFAULT;
83	}
84
85	return ret;
86}
87
88SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
89		struct sigaction __user *, oact,
90		size_t, sigsetsize, void __user *, restorer)
91{
92	struct k_sigaction new_ka, old_ka;
93	int ret;
94
95	/* XXX: Don't preclude handling different sized sigset_t's.  */
96	if (sigsetsize != sizeof(sigset_t))
97		return -EINVAL;
98
99	if (act) {
100		new_ka.ka_restorer = restorer;
101		if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
102			return -EFAULT;
103	}
104
105	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
106
107	if (!ret && oact) {
108		if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
109			return -EFAULT;
110	}
111
112	return ret;
113}
114
115/*
116 * Do a signal return; undo the signal stack.
117 */
118
119#if _NSIG_WORDS > 1
120# error "Non SA_SIGINFO frame needs rearranging"
121#endif
122
123struct sigframe
124{
125	struct sigcontext sc;
126	unsigned int retcode[3];
127};
128
129struct rt_sigframe
130{
131	struct siginfo info;
132	struct ucontext uc;
133	unsigned int retcode[3];
134};
135
136/* If this changes, userland unwinders that Know Things about our signal
137   frame will break.  Do not undertake lightly.  It also implies an ABI
138   change wrt the size of siginfo_t, which may cause some pain.  */
139extern char compile_time_assert
140        [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
141
142#define INSN_MOV_R30_R16	0x47fe0410
143#define INSN_LDI_R0		0x201f0000
144#define INSN_CALLSYS		0x00000083
145
146static long
147restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
148{
149	unsigned long usp;
150	struct switch_stack *sw = (struct switch_stack *)regs - 1;
151	long i, err = __get_user(regs->pc, &sc->sc_pc);
152
153	current->restart_block.fn = do_no_restart_syscall;
154
155	sw->r26 = (unsigned long) ret_from_sys_call;
156
157	err |= __get_user(regs->r0, sc->sc_regs+0);
158	err |= __get_user(regs->r1, sc->sc_regs+1);
159	err |= __get_user(regs->r2, sc->sc_regs+2);
160	err |= __get_user(regs->r3, sc->sc_regs+3);
161	err |= __get_user(regs->r4, sc->sc_regs+4);
162	err |= __get_user(regs->r5, sc->sc_regs+5);
163	err |= __get_user(regs->r6, sc->sc_regs+6);
164	err |= __get_user(regs->r7, sc->sc_regs+7);
165	err |= __get_user(regs->r8, sc->sc_regs+8);
166	err |= __get_user(sw->r9, sc->sc_regs+9);
167	err |= __get_user(sw->r10, sc->sc_regs+10);
168	err |= __get_user(sw->r11, sc->sc_regs+11);
169	err |= __get_user(sw->r12, sc->sc_regs+12);
170	err |= __get_user(sw->r13, sc->sc_regs+13);
171	err |= __get_user(sw->r14, sc->sc_regs+14);
172	err |= __get_user(sw->r15, sc->sc_regs+15);
173	err |= __get_user(regs->r16, sc->sc_regs+16);
174	err |= __get_user(regs->r17, sc->sc_regs+17);
175	err |= __get_user(regs->r18, sc->sc_regs+18);
176	err |= __get_user(regs->r19, sc->sc_regs+19);
177	err |= __get_user(regs->r20, sc->sc_regs+20);
178	err |= __get_user(regs->r21, sc->sc_regs+21);
179	err |= __get_user(regs->r22, sc->sc_regs+22);
180	err |= __get_user(regs->r23, sc->sc_regs+23);
181	err |= __get_user(regs->r24, sc->sc_regs+24);
182	err |= __get_user(regs->r25, sc->sc_regs+25);
183	err |= __get_user(regs->r26, sc->sc_regs+26);
184	err |= __get_user(regs->r27, sc->sc_regs+27);
185	err |= __get_user(regs->r28, sc->sc_regs+28);
186	err |= __get_user(regs->gp, sc->sc_regs+29);
187	err |= __get_user(usp, sc->sc_regs+30);
188	wrusp(usp);
189
190	for (i = 0; i < 31; i++)
191		err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
192	err |= __get_user(sw->fp[31], &sc->sc_fpcr);
193
194	return err;
195}
196
197/* Note that this syscall is also used by setcontext(3) to install
198   a given sigcontext.  This because it's impossible to set *all*
199   registers and transfer control from userland.  */
200
201asmlinkage void
202do_sigreturn(struct sigcontext __user *sc)
203{
204	struct pt_regs *regs = current_pt_regs();
205	sigset_t set;
206
207	/* Verify that it's a good sigcontext before using it */
208	if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
209		goto give_sigsegv;
210	if (__get_user(set.sig[0], &sc->sc_mask))
211		goto give_sigsegv;
212
213	set_current_blocked(&set);
214
215	if (restore_sigcontext(sc, regs))
216		goto give_sigsegv;
217
218	/* Send SIGTRAP if we're single-stepping: */
219	if (ptrace_cancel_bpt (current)) {
220		siginfo_t info;
221
222		info.si_signo = SIGTRAP;
223		info.si_errno = 0;
224		info.si_code = TRAP_BRKPT;
225		info.si_addr = (void __user *) regs->pc;
226		info.si_trapno = 0;
227		send_sig_info(SIGTRAP, &info, current);
228	}
229	return;
230
231give_sigsegv:
232	force_sig(SIGSEGV, current);
233}
234
235asmlinkage void
236do_rt_sigreturn(struct rt_sigframe __user *frame)
237{
238	struct pt_regs *regs = current_pt_regs();
239	sigset_t set;
240
241	/* Verify that it's a good ucontext_t before using it */
242	if (!access_ok(VERIFY_READ, &frame->uc, sizeof(frame->uc)))
243		goto give_sigsegv;
244	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
245		goto give_sigsegv;
246
247	set_current_blocked(&set);
248
249	if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
250		goto give_sigsegv;
251
252	/* Send SIGTRAP if we're single-stepping: */
253	if (ptrace_cancel_bpt (current)) {
254		siginfo_t info;
255
256		info.si_signo = SIGTRAP;
257		info.si_errno = 0;
258		info.si_code = TRAP_BRKPT;
259		info.si_addr = (void __user *) regs->pc;
260		info.si_trapno = 0;
261		send_sig_info(SIGTRAP, &info, current);
262	}
263	return;
264
265give_sigsegv:
266	force_sig(SIGSEGV, current);
267}
268
269
270/*
271 * Set up a signal frame.
272 */
273
274static inline void __user *
275get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
276{
277	return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
278}
279
280static long
281setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
282		 unsigned long mask, unsigned long sp)
283{
284	struct switch_stack *sw = (struct switch_stack *)regs - 1;
285	long i, err = 0;
286
287	err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
288	err |= __put_user(mask, &sc->sc_mask);
289	err |= __put_user(regs->pc, &sc->sc_pc);
290	err |= __put_user(8, &sc->sc_ps);
291
292	err |= __put_user(regs->r0 , sc->sc_regs+0);
293	err |= __put_user(regs->r1 , sc->sc_regs+1);
294	err |= __put_user(regs->r2 , sc->sc_regs+2);
295	err |= __put_user(regs->r3 , sc->sc_regs+3);
296	err |= __put_user(regs->r4 , sc->sc_regs+4);
297	err |= __put_user(regs->r5 , sc->sc_regs+5);
298	err |= __put_user(regs->r6 , sc->sc_regs+6);
299	err |= __put_user(regs->r7 , sc->sc_regs+7);
300	err |= __put_user(regs->r8 , sc->sc_regs+8);
301	err |= __put_user(sw->r9   , sc->sc_regs+9);
302	err |= __put_user(sw->r10  , sc->sc_regs+10);
303	err |= __put_user(sw->r11  , sc->sc_regs+11);
304	err |= __put_user(sw->r12  , sc->sc_regs+12);
305	err |= __put_user(sw->r13  , sc->sc_regs+13);
306	err |= __put_user(sw->r14  , sc->sc_regs+14);
307	err |= __put_user(sw->r15  , sc->sc_regs+15);
308	err |= __put_user(regs->r16, sc->sc_regs+16);
309	err |= __put_user(regs->r17, sc->sc_regs+17);
310	err |= __put_user(regs->r18, sc->sc_regs+18);
311	err |= __put_user(regs->r19, sc->sc_regs+19);
312	err |= __put_user(regs->r20, sc->sc_regs+20);
313	err |= __put_user(regs->r21, sc->sc_regs+21);
314	err |= __put_user(regs->r22, sc->sc_regs+22);
315	err |= __put_user(regs->r23, sc->sc_regs+23);
316	err |= __put_user(regs->r24, sc->sc_regs+24);
317	err |= __put_user(regs->r25, sc->sc_regs+25);
318	err |= __put_user(regs->r26, sc->sc_regs+26);
319	err |= __put_user(regs->r27, sc->sc_regs+27);
320	err |= __put_user(regs->r28, sc->sc_regs+28);
321	err |= __put_user(regs->gp , sc->sc_regs+29);
322	err |= __put_user(sp, sc->sc_regs+30);
323	err |= __put_user(0, sc->sc_regs+31);
324
325	for (i = 0; i < 31; i++)
326		err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
327	err |= __put_user(0, sc->sc_fpregs+31);
328	err |= __put_user(sw->fp[31], &sc->sc_fpcr);
329
330	err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
331	err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
332	err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
333
334	return err;
335}
336
337static int
338setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
339{
340	unsigned long oldsp, r26, err = 0;
341	struct sigframe __user *frame;
342
343	oldsp = rdusp();
344	frame = get_sigframe(ksig, oldsp, sizeof(*frame));
345	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
346		return -EFAULT;
347
348	err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
349	if (err)
350		return -EFAULT;
351
352	/* Set up to return from userspace.  If provided, use a stub
353	   already in userspace.  */
354	r26 = (unsigned long) ksig->ka.ka_restorer;
355	if (!r26) {
356		err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
357		err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
358		err |= __put_user(INSN_CALLSYS, frame->retcode+2);
359		imb();
360		r26 = (unsigned long) frame->retcode;
361	}
362
363	/* Check that everything was written properly.  */
364	if (err)
365		return err;
366
367	/* "Return" to the handler */
368	regs->r26 = r26;
369	regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
370	regs->r16 = ksig->sig;			/* a0: signal number */
371	regs->r17 = 0;				/* a1: exception code */
372	regs->r18 = (unsigned long) &frame->sc;	/* a2: sigcontext pointer */
373	wrusp((unsigned long) frame);
374
375#if DEBUG_SIG
376	printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
377		current->comm, current->pid, frame, regs->pc, regs->r26);
378#endif
379	return 0;
380}
381
382static int
383setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
384{
385	unsigned long oldsp, r26, err = 0;
386	struct rt_sigframe __user *frame;
387
388	oldsp = rdusp();
389	frame = get_sigframe(ksig, oldsp, sizeof(*frame));
390	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
391		return -EFAULT;
392
393	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
394
395	/* Create the ucontext.  */
396	err |= __put_user(0, &frame->uc.uc_flags);
397	err |= __put_user(0, &frame->uc.uc_link);
398	err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
399	err |= __save_altstack(&frame->uc.uc_stack, oldsp);
400	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
401				set->sig[0], oldsp);
402	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
403	if (err)
404		return -EFAULT;
405
406	/* Set up to return from userspace.  If provided, use a stub
407	   already in userspace.  */
408	r26 = (unsigned long) ksig->ka.ka_restorer;
409	if (!r26) {
410		err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
411		err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
412				  frame->retcode+1);
413		err |= __put_user(INSN_CALLSYS, frame->retcode+2);
414		imb();
415		r26 = (unsigned long) frame->retcode;
416	}
417
418	if (err)
419		return -EFAULT;
420
421	/* "Return" to the handler */
422	regs->r26 = r26;
423	regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
424	regs->r16 = ksig->sig;			  /* a0: signal number */
425	regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
426	regs->r18 = (unsigned long) &frame->uc;	  /* a2: ucontext pointer */
427	wrusp((unsigned long) frame);
428
429#if DEBUG_SIG
430	printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
431		current->comm, current->pid, frame, regs->pc, regs->r26);
432#endif
433
434	return 0;
435}
436
437
438/*
439 * OK, we're invoking a handler.
440 */
441static inline void
442handle_signal(struct ksignal *ksig, struct pt_regs *regs)
443{
444	sigset_t *oldset = sigmask_to_save();
445	int ret;
446
447	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
448		ret = setup_rt_frame(ksig, oldset, regs);
449	else
450		ret = setup_frame(ksig, oldset, regs);
451
452	signal_setup_done(ret, ksig, 0);
453}
454
455static inline void
456syscall_restart(unsigned long r0, unsigned long r19,
457		struct pt_regs *regs, struct k_sigaction *ka)
458{
459	switch (regs->r0) {
460	case ERESTARTSYS:
461		if (!(ka->sa.sa_flags & SA_RESTART)) {
462		case ERESTARTNOHAND:
463			regs->r0 = EINTR;
464			break;
465		}
466		/* fallthrough */
467	case ERESTARTNOINTR:
468		regs->r0 = r0;	/* reset v0 and a3 and replay syscall */
469		regs->r19 = r19;
470		regs->pc -= 4;
471		break;
472	case ERESTART_RESTARTBLOCK:
473		regs->r0 = EINTR;
474		break;
475	}
476}
477
478
479/*
480 * Note that 'init' is a special process: it doesn't get signals it doesn't
481 * want to handle. Thus you cannot kill init even with a SIGKILL even by
482 * mistake.
483 *
484 * Note that we go through the signals twice: once to check the signals that
485 * the kernel can handle, and then we build all the user-level signal handling
486 * stack-frames in one go after that.
487 *
488 * "r0" and "r19" are the registers we need to restore for system call
489 * restart. "r0" is also used as an indicator whether we can restart at
490 * all (if we get here from anything but a syscall return, it will be 0)
491 */
492static void
493do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
494{
495	unsigned long single_stepping = ptrace_cancel_bpt(current);
496	struct ksignal ksig;
497
498	/* This lets the debugger run, ... */
499	if (get_signal(&ksig)) {
500		/* ... so re-check the single stepping. */
501		single_stepping |= ptrace_cancel_bpt(current);
502		/* Whee!  Actually deliver the signal.  */
503		if (r0)
504			syscall_restart(r0, r19, regs, &ksig.ka);
505		handle_signal(&ksig, regs);
506	} else {
507		single_stepping |= ptrace_cancel_bpt(current);
508		if (r0) {
509			switch (regs->r0) {
510			case ERESTARTNOHAND:
511			case ERESTARTSYS:
512			case ERESTARTNOINTR:
513				/* Reset v0 and a3 and replay syscall.  */
514				regs->r0 = r0;
515				regs->r19 = r19;
516				regs->pc -= 4;
517				break;
518			case ERESTART_RESTARTBLOCK:
519				/* Set v0 to the restart_syscall and replay */
520				regs->r0 = __NR_restart_syscall;
521				regs->pc -= 4;
522				break;
523			}
524		}
525		restore_saved_sigmask();
526	}
527	if (single_stepping)
528		ptrace_set_bpt(current);	/* re-set breakpoint */
529}
530
531void
532do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
533		 unsigned long r0, unsigned long r19)
534{
535	do {
536		if (thread_flags & _TIF_NEED_RESCHED) {
537			schedule();
538		} else {
539			local_irq_enable();
540			if (thread_flags & _TIF_SIGPENDING) {
541				do_signal(regs, r0, r19);
542				r0 = 0;
543			} else {
544				clear_thread_flag(TIF_NOTIFY_RESUME);
545				tracehook_notify_resume(regs);
546			}
547		}
548		local_irq_disable();
549		thread_flags = current_thread_info()->flags;
550	} while (thread_flags & _TIF_WORK_MASK);
551}
552