1/*
2 * arch/xtensa/kernel/signal.c
3 *
4 * Default platform functions.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License.  See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2005, 2006 Tensilica Inc.
11 * Copyright (C) 1991, 1992  Linus Torvalds
12 * 1997-11-28  Modified for POSIX.1b signals by Richard Henderson
13 *
14 * Chris Zankel <chris@zankel.net>
15 * Joe Taylor <joe@tensilica.com>
16 */
17
18#include <linux/signal.h>
19#include <linux/errno.h>
20#include <linux/ptrace.h>
21#include <linux/personality.h>
22#include <linux/freezer.h>
23
24#include <asm/ucontext.h>
25#include <asm/uaccess.h>
26#include <asm/cacheflush.h>
27#include <asm/coprocessor.h>
28#include <asm/unistd.h>
29
30#define DEBUG_SIG  0
31
32#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
33
34asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
35
36extern struct task_struct *coproc_owners[];
37
38struct rt_sigframe
39{
40	struct siginfo info;
41	struct ucontext uc;
42	struct {
43		xtregs_opt_t opt;
44		xtregs_user_t user;
45#if XTENSA_HAVE_COPROCESSORS
46		xtregs_coprocessor_t cp;
47#endif
48	} xtregs;
49	unsigned char retcode[6];
50	unsigned int window[4];
51};
52
53/*
54 * Flush register windows stored in pt_regs to stack.
55 * Returns 1 for errors.
56 */
57
58int
59flush_window_regs_user(struct pt_regs *regs)
60{
61	const unsigned long ws = regs->windowstart;
62	const unsigned long wb = regs->windowbase;
63	unsigned long sp = 0;
64	unsigned long wm;
65	int err = 1;
66	int base;
67
68	/* Return if no other frames. */
69
70	if (regs->wmask == 1)
71		return 0;
72
73	/* Rotate windowmask and skip empty frames. */
74
75	wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
76	base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
77
78	/* For call8 or call12 frames, we need the previous stack pointer. */
79
80	if ((regs->wmask & 2) == 0)
81		if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
82			goto errout;
83
84	/* Spill frames to stack. */
85
86	while (base < XCHAL_NUM_AREGS / 4) {
87
88		int m = (wm >> base);
89		int inc = 0;
90
91		/* Save registers a4..a7 (call8) or a4...a11 (call12) */
92
93		if (m & 2) {			/* call4 */
94			inc = 1;
95
96		} else if (m & 4) {		/* call8 */
97			if (copy_to_user((void*)(sp - 32),
98					   &regs->areg[(base + 1) * 4], 16))
99				goto errout;
100			inc = 2;
101
102		} else if (m & 8) {	/* call12 */
103			if (copy_to_user((void*)(sp - 48),
104					   &regs->areg[(base + 1) * 4], 32))
105				goto errout;
106			inc = 3;
107		}
108
109		/* Save current frame a0..a3 under next SP */
110
111		sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
112		if (copy_to_user((void*)(sp - 16), &regs->areg[base * 4], 16))
113			goto errout;
114
115		/* Get current stack pointer for next loop iteration. */
116
117		sp = regs->areg[base * 4 + 1];
118		base += inc;
119	}
120
121	regs->wmask = 1;
122	regs->windowstart = 1 << wb;
123
124	return 0;
125
126errout:
127	return err;
128}
129
130/*
131 * Note: We don't copy double exception 'regs', we have to finish double exc.
132 * first before we return to signal handler! This dbl.exc.handler might cause
133 * another double exception, but I think we are fine as the situation is the
134 * same as if we had returned to the signal handerl and got an interrupt
135 * immediately...
136 */
137
138static int
139setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
140{
141	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
142	struct thread_info *ti = current_thread_info();
143	int err = 0;
144
145#define COPY(x)	err |= __put_user(regs->x, &sc->sc_##x)
146	COPY(pc);
147	COPY(ps);
148	COPY(lbeg);
149	COPY(lend);
150	COPY(lcount);
151	COPY(sar);
152#undef COPY
153
154	err |= flush_window_regs_user(regs);
155	err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
156	err |= __put_user(0, &sc->sc_xtregs);
157
158	if (err)
159		return err;
160
161#if XTENSA_HAVE_COPROCESSORS
162	coprocessor_flush_all(ti);
163	coprocessor_release_all(ti);
164	err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
165			      sizeof (frame->xtregs.cp));
166#endif
167	err |= __copy_to_user(&frame->xtregs.opt, &regs->xtregs_opt,
168			      sizeof (xtregs_opt_t));
169	err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
170			      sizeof (xtregs_user_t));
171
172	err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);
173
174	return err;
175}
176
177static int
178restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
179{
180	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
181	struct thread_info *ti = current_thread_info();
182	unsigned int err = 0;
183	unsigned long ps;
184
185#define COPY(x)	err |= __get_user(regs->x, &sc->sc_##x)
186	COPY(pc);
187	COPY(lbeg);
188	COPY(lend);
189	COPY(lcount);
190	COPY(sar);
191#undef COPY
192
193	/* All registers were flushed to stack. Start with a prestine frame. */
194
195	regs->wmask = 1;
196	regs->windowbase = 0;
197	regs->windowstart = 1;
198
199	regs->syscall = -1;		/* disable syscall checks */
200
201	/* For PS, restore only PS.CALLINC.
202	 * Assume that all other bits are either the same as for the signal
203	 * handler, or the user mode value doesn't matter (e.g. PS.OWB).
204	 */
205	err |= __get_user(ps, &sc->sc_ps);
206	regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);
207
208	/* Additional corruption checks */
209
210	if ((regs->lcount > 0)
211	    && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
212		err = 1;
213
214	err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);
215
216	if (err)
217		return err;
218
219 	/* The signal handler may have used coprocessors in which
220	 * case they are still enabled.  We disable them to force a
221	 * reloading of the original task's CP state by the lazy
222	 * context-switching mechanisms of CP exception handling.
223	 * Also, we essentially discard any coprocessor state that the
224	 * signal handler created. */
225
226#if XTENSA_HAVE_COPROCESSORS
227	coprocessor_release_all(ti);
228	err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
229				sizeof (frame->xtregs.cp));
230#endif
231	err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
232				sizeof (xtregs_user_t));
233	err |= __copy_from_user(&regs->xtregs_opt, &frame->xtregs.opt,
234				sizeof (xtregs_opt_t));
235
236	return err;
237}
238
239
240/*
241 * Do a signal return; undo the signal stack.
242 */
243
244asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3,
245				    long a4, long a5, struct pt_regs *regs)
246{
247	struct rt_sigframe __user *frame;
248	sigset_t set;
249	int ret;
250
251	if (regs->depc > 64)
252		panic("rt_sigreturn in double exception!\n");
253
254	frame = (struct rt_sigframe __user *) regs->areg[1];
255
256	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
257		goto badframe;
258
259	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
260		goto badframe;
261
262	sigdelsetmask(&set, ~_BLOCKABLE);
263	set_current_blocked(&set);
264
265	if (restore_sigcontext(regs, frame))
266		goto badframe;
267
268	ret = regs->areg[2];
269
270	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->areg[1]) == -EFAULT)
271		goto badframe;
272
273	return ret;
274
275badframe:
276	force_sig(SIGSEGV, current);
277	return 0;
278}
279
280
281
282/*
283 * Set up a signal frame.
284 */
285
286static int
287gen_return_code(unsigned char *codemem)
288{
289	int err = 0;
290
291	/*
292	 * The 12-bit immediate is really split up within the 24-bit MOVI
293	 * instruction.  As long as the above system call numbers fit within
294	 * 8-bits, the following code works fine. See the Xtensa ISA for
295	 * details.
296	 */
297
298#if __NR_rt_sigreturn > 255
299# error Generating the MOVI instruction below breaks!
300#endif
301
302#ifdef __XTENSA_EB__   /* Big Endian version */
303	/* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
304	err |= __put_user(0x22, &codemem[0]);
305	err |= __put_user(0x0a, &codemem[1]);
306	err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
307	/* Generate instruction:  SYSCALL */
308	err |= __put_user(0x00, &codemem[3]);
309	err |= __put_user(0x05, &codemem[4]);
310	err |= __put_user(0x00, &codemem[5]);
311
312#elif defined __XTENSA_EL__   /* Little Endian version */
313	/* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
314	err |= __put_user(0x22, &codemem[0]);
315	err |= __put_user(0xa0, &codemem[1]);
316	err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
317	/* Generate instruction:  SYSCALL */
318	err |= __put_user(0x00, &codemem[3]);
319	err |= __put_user(0x50, &codemem[4]);
320	err |= __put_user(0x00, &codemem[5]);
321#else
322# error Must use compiler for Xtensa processors.
323#endif
324
325	/* Flush generated code out of the data cache */
326
327	if (err == 0) {
328		__invalidate_icache_range((unsigned long)codemem, 6UL);
329		__flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
330	}
331
332	return err;
333}
334
335
336static int setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
337		       sigset_t *set, struct pt_regs *regs)
338{
339	struct rt_sigframe *frame;
340	int err = 0;
341	int signal;
342	unsigned long sp, ra;
343
344	sp = regs->areg[1];
345
346	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) {
347		sp = current->sas_ss_sp + current->sas_ss_size;
348	}
349
350	frame = (void *)((sp - sizeof(*frame)) & -16ul);
351
352	if (regs->depc > 64)
353		panic ("Double exception sys_sigreturn\n");
354
355	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) {
356		goto give_sigsegv;
357	}
358
359	signal = current_thread_info()->exec_domain
360		&& current_thread_info()->exec_domain->signal_invmap
361		&& sig < 32
362		? current_thread_info()->exec_domain->signal_invmap[sig]
363		: sig;
364
365	if (ka->sa.sa_flags & SA_SIGINFO) {
366		err |= copy_siginfo_to_user(&frame->info, info);
367	}
368
369	/* Create the user context.  */
370
371	err |= __put_user(0, &frame->uc.uc_flags);
372	err |= __put_user(0, &frame->uc.uc_link);
373	err |= __put_user((void *)current->sas_ss_sp,
374			  &frame->uc.uc_stack.ss_sp);
375	err |= __put_user(sas_ss_flags(regs->areg[1]),
376			  &frame->uc.uc_stack.ss_flags);
377	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
378	err |= setup_sigcontext(frame, regs);
379	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
380
381	if (ka->sa.sa_flags & SA_RESTORER) {
382		ra = (unsigned long)ka->sa.sa_restorer;
383	} else {
384
385		/* Create sys_rt_sigreturn syscall in stack frame */
386
387		err |= gen_return_code(frame->retcode);
388
389		if (err) {
390			goto give_sigsegv;
391		}
392		ra = (unsigned long) frame->retcode;
393	}
394
395	/*
396	 * Create signal handler execution context.
397	 * Return context not modified until this point.
398	 */
399
400	/* Set up registers for signal handler */
401	start_thread(regs, (unsigned long) ka->sa.sa_handler,
402		     (unsigned long) frame);
403
404	/* Set up a stack frame for a call4
405	 * Note: PS.CALLINC is set to one by start_thread
406	 */
407	regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
408	regs->areg[6] = (unsigned long) signal;
409	regs->areg[7] = (unsigned long) &frame->info;
410	regs->areg[8] = (unsigned long) &frame->uc;
411
412	/* Set access mode to USER_DS.  Nomenclature is outdated, but
413	 * functionality is used in uaccess.h
414	 */
415	set_fs(USER_DS);
416
417#if DEBUG_SIG
418	printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
419		current->comm, current->pid, signal, frame, regs->pc);
420#endif
421
422	return 0;
423
424give_sigsegv:
425	force_sigsegv(sig, current);
426	return -EFAULT;
427}
428
429/*
430 * Atomically swap in the new signal mask, and wait for a signal.
431 */
432
433asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset,
434    				     size_t sigsetsize,
435    				     long a2, long a3, long a4, long a5,
436				     struct pt_regs *regs)
437{
438	sigset_t saveset, newset;
439
440	/* XXX: Don't preclude handling different sized sigset_t's.  */
441	if (sigsetsize != sizeof(sigset_t))
442		return -EINVAL;
443
444	if (copy_from_user(&newset, unewset, sizeof(newset)))
445		return -EFAULT;
446
447	sigdelsetmask(&newset, ~_BLOCKABLE);
448	saveset = current->blocked;
449	set_current_blocked(&newset);
450
451	regs->areg[2] = -EINTR;
452	while (1) {
453		current->state = TASK_INTERRUPTIBLE;
454		schedule();
455		if (do_signal(regs, &saveset))
456			return -EINTR;
457	}
458}
459
460asmlinkage long xtensa_sigaltstack(const stack_t __user *uss,
461				   stack_t __user *uoss,
462    				   long a2, long a3, long a4, long a5,
463				   struct pt_regs *regs)
464{
465	return do_sigaltstack(uss, uoss, regs->areg[1]);
466}
467
468
469
470/*
471 * Note that 'init' is a special process: it doesn't get signals it doesn't
472 * want to handle. Thus you cannot kill init even with a SIGKILL even by
473 * mistake.
474 *
475 * Note that we go through the signals twice: once to check the signals that
476 * the kernel can handle, and then we build all the user-level signal handling
477 * stack-frames in one go after that.
478 */
479int do_signal(struct pt_regs *regs, sigset_t *oldset)
480{
481	siginfo_t info;
482	int signr;
483	struct k_sigaction ka;
484
485	if (!user_mode(regs))
486		return 0;
487
488	if (try_to_freeze())
489		goto no_signal;
490
491	if (!oldset)
492		oldset = &current->blocked;
493
494	task_pt_regs(current)->icountlevel = 0;
495
496	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
497
498	if (signr > 0) {
499		int ret;
500
501		/* Are we from a system call? */
502
503		if ((signed)regs->syscall >= 0) {
504
505			/* If so, check system call restarting.. */
506
507			switch (regs->areg[2]) {
508				case -ERESTARTNOHAND:
509				case -ERESTART_RESTARTBLOCK:
510					regs->areg[2] = -EINTR;
511					break;
512
513				case -ERESTARTSYS:
514					if (!(ka.sa.sa_flags & SA_RESTART)) {
515						regs->areg[2] = -EINTR;
516						break;
517					}
518					/* fallthrough */
519				case -ERESTARTNOINTR:
520					regs->areg[2] = regs->syscall;
521					regs->pc -= 3;
522					break;
523
524				default:
525					/* nothing to do */
526					if (regs->areg[2] != 0)
527					break;
528			}
529		}
530
531		/* Whee!  Actually deliver the signal.  */
532		/* Set up the stack frame */
533		ret = setup_frame(signr, &ka, &info, oldset, regs);
534		if (ret)
535			return ret;
536
537		block_sigmask(&ka, signr);
538		if (current->ptrace & PT_SINGLESTEP)
539			task_pt_regs(current)->icountlevel = 1;
540
541		return 1;
542	}
543
544no_signal:
545	/* Did we come from a system call? */
546	if ((signed) regs->syscall >= 0) {
547		/* Restart the system call - no handlers present */
548		switch (regs->areg[2]) {
549		case -ERESTARTNOHAND:
550		case -ERESTARTSYS:
551		case -ERESTARTNOINTR:
552			regs->areg[2] = regs->syscall;
553			regs->pc -= 3;
554			break;
555		case -ERESTART_RESTARTBLOCK:
556			regs->areg[2] = __NR_restart_syscall;
557			regs->pc -= 3;
558			break;
559		}
560	}
561	if (current->ptrace & PT_SINGLESTEP)
562		task_pt_regs(current)->icountlevel = 1;
563	return 0;
564}
565
566