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
34 asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
35
36 extern struct task_struct *coproc_owners[];
37
38 struct 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
58 int
flush_window_regs_user(struct pt_regs * regs)59 flush_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 ®s->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 ®s->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), ®s->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
126 errout:
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
138 static int
setup_sigcontext(struct rt_sigframe __user * frame,struct pt_regs * regs)139 setup_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, ®s->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
177 static int
restore_sigcontext(struct pt_regs * regs,struct rt_sigframe __user * frame)178 restore_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(®s->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
xtensa_rt_sigreturn(long a0,long a1,long a2,long a3,long a4,long a5,struct pt_regs * regs)244 asmlinkage 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 spin_lock_irq(¤t->sighand->siglock);
264 current->blocked = set;
265 recalc_sigpending();
266 spin_unlock_irq(¤t->sighand->siglock);
267
268 if (restore_sigcontext(regs, frame))
269 goto badframe;
270
271 ret = regs->areg[2];
272
273 if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->areg[1]) == -EFAULT)
274 goto badframe;
275
276 return ret;
277
278 badframe:
279 force_sig(SIGSEGV, current);
280 return 0;
281 }
282
283
284
285 /*
286 * Set up a signal frame.
287 */
288
289 static int
gen_return_code(unsigned char * codemem)290 gen_return_code(unsigned char *codemem)
291 {
292 int err = 0;
293
294 /*
295 * The 12-bit immediate is really split up within the 24-bit MOVI
296 * instruction. As long as the above system call numbers fit within
297 * 8-bits, the following code works fine. See the Xtensa ISA for
298 * details.
299 */
300
301 #if __NR_rt_sigreturn > 255
302 # error Generating the MOVI instruction below breaks!
303 #endif
304
305 #ifdef __XTENSA_EB__ /* Big Endian version */
306 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
307 err |= __put_user(0x22, &codemem[0]);
308 err |= __put_user(0x0a, &codemem[1]);
309 err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
310 /* Generate instruction: SYSCALL */
311 err |= __put_user(0x00, &codemem[3]);
312 err |= __put_user(0x05, &codemem[4]);
313 err |= __put_user(0x00, &codemem[5]);
314
315 #elif defined __XTENSA_EL__ /* Little Endian version */
316 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
317 err |= __put_user(0x22, &codemem[0]);
318 err |= __put_user(0xa0, &codemem[1]);
319 err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
320 /* Generate instruction: SYSCALL */
321 err |= __put_user(0x00, &codemem[3]);
322 err |= __put_user(0x50, &codemem[4]);
323 err |= __put_user(0x00, &codemem[5]);
324 #else
325 # error Must use compiler for Xtensa processors.
326 #endif
327
328 /* Flush generated code out of the data cache */
329
330 if (err == 0) {
331 __invalidate_icache_range((unsigned long)codemem, 6UL);
332 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
333 }
334
335 return err;
336 }
337
338
setup_frame(int sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)339 static void setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
340 sigset_t *set, struct pt_regs *regs)
341 {
342 struct rt_sigframe *frame;
343 int err = 0;
344 int signal;
345 unsigned long sp, ra;
346
347 sp = regs->areg[1];
348
349 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp)) {
350 sp = current->sas_ss_sp + current->sas_ss_size;
351 }
352
353 frame = (void *)((sp - sizeof(*frame)) & -16ul);
354
355 if (regs->depc > 64)
356 panic ("Double exception sys_sigreturn\n");
357
358 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) {
359 goto give_sigsegv;
360 }
361
362 signal = current_thread_info()->exec_domain
363 && current_thread_info()->exec_domain->signal_invmap
364 && sig < 32
365 ? current_thread_info()->exec_domain->signal_invmap[sig]
366 : sig;
367
368 if (ka->sa.sa_flags & SA_SIGINFO) {
369 err |= copy_siginfo_to_user(&frame->info, info);
370 }
371
372 /* Create the user context. */
373
374 err |= __put_user(0, &frame->uc.uc_flags);
375 err |= __put_user(0, &frame->uc.uc_link);
376 err |= __put_user((void *)current->sas_ss_sp,
377 &frame->uc.uc_stack.ss_sp);
378 err |= __put_user(sas_ss_flags(regs->areg[1]),
379 &frame->uc.uc_stack.ss_flags);
380 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
381 err |= setup_sigcontext(frame, regs);
382 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
383
384 if (ka->sa.sa_flags & SA_RESTORER) {
385 ra = (unsigned long)ka->sa.sa_restorer;
386 } else {
387
388 /* Create sys_rt_sigreturn syscall in stack frame */
389
390 err |= gen_return_code(frame->retcode);
391
392 if (err) {
393 goto give_sigsegv;
394 }
395 ra = (unsigned long) frame->retcode;
396 }
397
398 /*
399 * Create signal handler execution context.
400 * Return context not modified until this point.
401 */
402
403 /* Set up registers for signal handler */
404 start_thread(regs, (unsigned long) ka->sa.sa_handler,
405 (unsigned long) frame);
406
407 /* Set up a stack frame for a call4
408 * Note: PS.CALLINC is set to one by start_thread
409 */
410 regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
411 regs->areg[6] = (unsigned long) signal;
412 regs->areg[7] = (unsigned long) &frame->info;
413 regs->areg[8] = (unsigned long) &frame->uc;
414
415 /* Set access mode to USER_DS. Nomenclature is outdated, but
416 * functionality is used in uaccess.h
417 */
418 set_fs(USER_DS);
419
420 #if DEBUG_SIG
421 printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
422 current->comm, current->pid, signal, frame, regs->pc);
423 #endif
424
425 return;
426
427 give_sigsegv:
428 if (sig == SIGSEGV)
429 ka->sa.sa_handler = SIG_DFL;
430 force_sig(SIGSEGV, current);
431 }
432
433 /*
434 * Atomically swap in the new signal mask, and wait for a signal.
435 */
436
xtensa_rt_sigsuspend(sigset_t __user * unewset,size_t sigsetsize,long a2,long a3,long a4,long a5,struct pt_regs * regs)437 asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset,
438 size_t sigsetsize,
439 long a2, long a3, long a4, long a5,
440 struct pt_regs *regs)
441 {
442 sigset_t saveset, newset;
443
444 /* XXX: Don't preclude handling different sized sigset_t's. */
445 if (sigsetsize != sizeof(sigset_t))
446 return -EINVAL;
447
448 if (copy_from_user(&newset, unewset, sizeof(newset)))
449 return -EFAULT;
450
451 sigdelsetmask(&newset, ~_BLOCKABLE);
452 spin_lock_irq(¤t->sighand->siglock);
453 saveset = current->blocked;
454 current->blocked = newset;
455 recalc_sigpending();
456 spin_unlock_irq(¤t->sighand->siglock);
457
458 regs->areg[2] = -EINTR;
459 while (1) {
460 current->state = TASK_INTERRUPTIBLE;
461 schedule();
462 if (do_signal(regs, &saveset))
463 return -EINTR;
464 }
465 }
466
xtensa_sigaltstack(const stack_t __user * uss,stack_t __user * uoss,long a2,long a3,long a4,long a5,struct pt_regs * regs)467 asmlinkage long xtensa_sigaltstack(const stack_t __user *uss,
468 stack_t __user *uoss,
469 long a2, long a3, long a4, long a5,
470 struct pt_regs *regs)
471 {
472 return do_sigaltstack(uss, uoss, regs->areg[1]);
473 }
474
475
476
477 /*
478 * Note that 'init' is a special process: it doesn't get signals it doesn't
479 * want to handle. Thus you cannot kill init even with a SIGKILL even by
480 * mistake.
481 *
482 * Note that we go through the signals twice: once to check the signals that
483 * the kernel can handle, and then we build all the user-level signal handling
484 * stack-frames in one go after that.
485 */
do_signal(struct pt_regs * regs,sigset_t * oldset)486 int do_signal(struct pt_regs *regs, sigset_t *oldset)
487 {
488 siginfo_t info;
489 int signr;
490 struct k_sigaction ka;
491
492 if (!user_mode(regs))
493 return 0;
494
495 if (try_to_freeze())
496 goto no_signal;
497
498 if (!oldset)
499 oldset = ¤t->blocked;
500
501 task_pt_regs(current)->icountlevel = 0;
502
503 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
504
505 if (signr > 0) {
506
507 /* Are we from a system call? */
508
509 if ((signed)regs->syscall >= 0) {
510
511 /* If so, check system call restarting.. */
512
513 switch (regs->areg[2]) {
514 case -ERESTARTNOHAND:
515 case -ERESTART_RESTARTBLOCK:
516 regs->areg[2] = -EINTR;
517 break;
518
519 case -ERESTARTSYS:
520 if (!(ka.sa.sa_flags & SA_RESTART)) {
521 regs->areg[2] = -EINTR;
522 break;
523 }
524 /* fallthrough */
525 case -ERESTARTNOINTR:
526 regs->areg[2] = regs->syscall;
527 regs->pc -= 3;
528 break;
529
530 default:
531 /* nothing to do */
532 if (regs->areg[2] != 0)
533 break;
534 }
535 }
536
537 /* Whee! Actually deliver the signal. */
538 /* Set up the stack frame */
539 setup_frame(signr, &ka, &info, oldset, regs);
540
541 if (ka.sa.sa_flags & SA_ONESHOT)
542 ka.sa.sa_handler = SIG_DFL;
543
544 spin_lock_irq(¤t->sighand->siglock);
545 sigorsets(¤t->blocked, ¤t->blocked, &ka.sa.sa_mask);
546 if (!(ka.sa.sa_flags & SA_NODEFER))
547 sigaddset(¤t->blocked, signr);
548 recalc_sigpending();
549 spin_unlock_irq(¤t->sighand->siglock);
550 if (current->ptrace & PT_SINGLESTEP)
551 task_pt_regs(current)->icountlevel = 1;
552
553 return 1;
554 }
555
556 no_signal:
557 /* Did we come from a system call? */
558 if ((signed) regs->syscall >= 0) {
559 /* Restart the system call - no handlers present */
560 switch (regs->areg[2]) {
561 case -ERESTARTNOHAND:
562 case -ERESTARTSYS:
563 case -ERESTARTNOINTR:
564 regs->areg[2] = regs->syscall;
565 regs->pc -= 3;
566 break;
567 case -ERESTART_RESTARTBLOCK:
568 regs->areg[2] = __NR_restart_syscall;
569 regs->pc -= 3;
570 break;
571 }
572 }
573 if (current->ptrace & PT_SINGLESTEP)
574 task_pt_regs(current)->icountlevel = 1;
575 return 0;
576 }
577
578