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/tracehook.h>
23 #include <linux/sched/task_stack.h>
24
25 #include <asm/ucontext.h>
26 #include <linux/uaccess.h>
27 #include <asm/cacheflush.h>
28 #include <asm/coprocessor.h>
29 #include <asm/unistd.h>
30
31 extern struct task_struct *coproc_owners[];
32
33 struct rt_sigframe
34 {
35 struct siginfo info;
36 struct ucontext uc;
37 struct {
38 xtregs_opt_t opt;
39 xtregs_user_t user;
40 #if XTENSA_HAVE_COPROCESSORS
41 xtregs_coprocessor_t cp;
42 #endif
43 } xtregs;
44 unsigned char retcode[6];
45 unsigned int window[4];
46 };
47
48 #if defined(USER_SUPPORT_WINDOWED)
49 /*
50 * Flush register windows stored in pt_regs to stack.
51 * Returns 1 for errors.
52 */
53
54 static int
flush_window_regs_user(struct pt_regs * regs)55 flush_window_regs_user(struct pt_regs *regs)
56 {
57 const unsigned long ws = regs->windowstart;
58 const unsigned long wb = regs->windowbase;
59 unsigned long sp = 0;
60 unsigned long wm;
61 int err = 1;
62 int base;
63
64 /* Return if no other frames. */
65
66 if (regs->wmask == 1)
67 return 0;
68
69 /* Rotate windowmask and skip empty frames. */
70
71 wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
72 base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
73
74 /* For call8 or call12 frames, we need the previous stack pointer. */
75
76 if ((regs->wmask & 2) == 0)
77 if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
78 goto errout;
79
80 /* Spill frames to stack. */
81
82 while (base < XCHAL_NUM_AREGS / 4) {
83
84 int m = (wm >> base);
85 int inc = 0;
86
87 /* Save registers a4..a7 (call8) or a4...a11 (call12) */
88
89 if (m & 2) { /* call4 */
90 inc = 1;
91
92 } else if (m & 4) { /* call8 */
93 if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4),
94 ®s->areg[(base + 1) * 4], 16))
95 goto errout;
96 inc = 2;
97
98 } else if (m & 8) { /* call12 */
99 if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4),
100 ®s->areg[(base + 1) * 4], 32))
101 goto errout;
102 inc = 3;
103 }
104
105 /* Save current frame a0..a3 under next SP */
106
107 sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
108 if (copy_to_user(&SPILL_SLOT(sp, 0), ®s->areg[base * 4], 16))
109 goto errout;
110
111 /* Get current stack pointer for next loop iteration. */
112
113 sp = regs->areg[base * 4 + 1];
114 base += inc;
115 }
116
117 regs->wmask = 1;
118 regs->windowstart = 1 << wb;
119
120 return 0;
121
122 errout:
123 return err;
124 }
125 #else
126 static int
flush_window_regs_user(struct pt_regs * regs)127 flush_window_regs_user(struct pt_regs *regs)
128 {
129 return 0;
130 }
131 #endif
132
133 /*
134 * Note: We don't copy double exception 'regs', we have to finish double exc.
135 * first before we return to signal handler! This dbl.exc.handler might cause
136 * another double exception, but I think we are fine as the situation is the
137 * same as if we had returned to the signal handerl and got an interrupt
138 * immediately...
139 */
140
141 static int
setup_sigcontext(struct rt_sigframe __user * frame,struct pt_regs * regs)142 setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
143 {
144 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
145 struct thread_info *ti = current_thread_info();
146 int err = 0;
147
148 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x)
149 COPY(pc);
150 COPY(ps);
151 COPY(lbeg);
152 COPY(lend);
153 COPY(lcount);
154 COPY(sar);
155 #undef COPY
156
157 err |= flush_window_regs_user(regs);
158 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
159 err |= __put_user(0, &sc->sc_xtregs);
160
161 if (err)
162 return err;
163
164 #if XTENSA_HAVE_COPROCESSORS
165 coprocessor_flush_all(ti);
166 coprocessor_release_all(ti);
167 err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
168 sizeof (frame->xtregs.cp));
169 #endif
170 err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt,
171 sizeof (xtregs_opt_t));
172 err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
173 sizeof (xtregs_user_t));
174
175 err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);
176
177 return err;
178 }
179
180 static int
restore_sigcontext(struct pt_regs * regs,struct rt_sigframe __user * frame)181 restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
182 {
183 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
184 struct thread_info *ti = current_thread_info();
185 unsigned int err = 0;
186 unsigned long ps;
187
188 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x)
189 COPY(pc);
190 COPY(lbeg);
191 COPY(lend);
192 COPY(lcount);
193 COPY(sar);
194 #undef COPY
195
196 /* All registers were flushed to stack. Start with a pristine frame. */
197
198 regs->wmask = 1;
199 regs->windowbase = 0;
200 regs->windowstart = 1;
201
202 regs->syscall = NO_SYSCALL; /* disable syscall checks */
203
204 /* For PS, restore only PS.CALLINC.
205 * Assume that all other bits are either the same as for the signal
206 * handler, or the user mode value doesn't matter (e.g. PS.OWB).
207 */
208 err |= __get_user(ps, &sc->sc_ps);
209 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);
210
211 /* Additional corruption checks */
212
213 if ((regs->lcount > 0)
214 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
215 err = 1;
216
217 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);
218
219 if (err)
220 return err;
221
222 /* The signal handler may have used coprocessors in which
223 * case they are still enabled. We disable them to force a
224 * reloading of the original task's CP state by the lazy
225 * context-switching mechanisms of CP exception handling.
226 * Also, we essentially discard any coprocessor state that the
227 * signal handler created. */
228
229 #if XTENSA_HAVE_COPROCESSORS
230 coprocessor_release_all(ti);
231 err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
232 sizeof (frame->xtregs.cp));
233 #endif
234 err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
235 sizeof (xtregs_user_t));
236 err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt,
237 sizeof (xtregs_opt_t));
238
239 return err;
240 }
241
242
243 /*
244 * Do a signal return; undo the signal stack.
245 */
246
xtensa_rt_sigreturn(void)247 asmlinkage long xtensa_rt_sigreturn(void)
248 {
249 struct pt_regs *regs = current_pt_regs();
250 struct rt_sigframe __user *frame;
251 sigset_t set;
252 int ret;
253
254 /* Always make any pending restarted system calls return -EINTR */
255 current->restart_block.fn = do_no_restart_syscall;
256
257 if (regs->depc > 64)
258 panic("rt_sigreturn in double exception!\n");
259
260 frame = (struct rt_sigframe __user *) regs->areg[1];
261
262 if (!access_ok(frame, sizeof(*frame)))
263 goto badframe;
264
265 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
266 goto badframe;
267
268 set_current_blocked(&set);
269
270 if (restore_sigcontext(regs, frame))
271 goto badframe;
272
273 ret = regs->areg[2];
274
275 if (restore_altstack(&frame->uc.uc_stack))
276 goto badframe;
277
278 return ret;
279
280 badframe:
281 force_sig(SIGSEGV);
282 return 0;
283 }
284
285
286
287 /*
288 * Set up a signal frame.
289 */
290
291 static int
gen_return_code(unsigned char * codemem)292 gen_return_code(unsigned char *codemem)
293 {
294 int err = 0;
295
296 /*
297 * The 12-bit immediate is really split up within the 24-bit MOVI
298 * instruction. As long as the above system call numbers fit within
299 * 8-bits, the following code works fine. See the Xtensa ISA for
300 * details.
301 */
302
303 #if __NR_rt_sigreturn > 255
304 # error Generating the MOVI instruction below breaks!
305 #endif
306
307 #ifdef __XTENSA_EB__ /* Big Endian version */
308 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
309 err |= __put_user(0x22, &codemem[0]);
310 err |= __put_user(0x0a, &codemem[1]);
311 err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
312 /* Generate instruction: SYSCALL */
313 err |= __put_user(0x00, &codemem[3]);
314 err |= __put_user(0x05, &codemem[4]);
315 err |= __put_user(0x00, &codemem[5]);
316
317 #elif defined __XTENSA_EL__ /* Little Endian version */
318 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
319 err |= __put_user(0x22, &codemem[0]);
320 err |= __put_user(0xa0, &codemem[1]);
321 err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
322 /* Generate instruction: SYSCALL */
323 err |= __put_user(0x00, &codemem[3]);
324 err |= __put_user(0x50, &codemem[4]);
325 err |= __put_user(0x00, &codemem[5]);
326 #else
327 # error Must use compiler for Xtensa processors.
328 #endif
329
330 /* Flush generated code out of the data cache */
331
332 if (err == 0) {
333 __invalidate_icache_range((unsigned long)codemem, 6UL);
334 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
335 }
336
337 return err;
338 }
339
340
setup_frame(struct ksignal * ksig,sigset_t * set,struct pt_regs * regs)341 static int setup_frame(struct ksignal *ksig, sigset_t *set,
342 struct pt_regs *regs)
343 {
344 struct rt_sigframe *frame;
345 int err = 0, sig = ksig->sig;
346 unsigned long sp, ra, tp, ps;
347 unsigned int base;
348
349 sp = regs->areg[1];
350
351 if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) {
352 sp = current->sas_ss_sp + current->sas_ss_size;
353 }
354
355 frame = (void *)((sp - sizeof(*frame)) & -16ul);
356
357 if (regs->depc > 64)
358 panic ("Double exception sys_sigreturn\n");
359
360 if (!access_ok(frame, sizeof(*frame))) {
361 return -EFAULT;
362 }
363
364 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
365 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
366 }
367
368 /* Create the user context. */
369
370 err |= __put_user(0, &frame->uc.uc_flags);
371 err |= __put_user(0, &frame->uc.uc_link);
372 err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]);
373 err |= setup_sigcontext(frame, regs);
374 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
375
376 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
377 ra = (unsigned long)ksig->ka.sa.sa_restorer;
378 } else {
379
380 /* Create sys_rt_sigreturn syscall in stack frame */
381
382 err |= gen_return_code(frame->retcode);
383
384 if (err) {
385 return -EFAULT;
386 }
387 ra = (unsigned long) frame->retcode;
388 }
389
390 /*
391 * Create signal handler execution context.
392 * Return context not modified until this point.
393 */
394
395 /* Set up registers for signal handler; preserve the threadptr */
396 tp = regs->threadptr;
397 ps = regs->ps;
398 start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler,
399 (unsigned long) frame);
400
401 /* Set up a stack frame for a call4 if userspace uses windowed ABI */
402 if (ps & PS_WOE_MASK) {
403 base = 4;
404 regs->areg[base] =
405 (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
406 ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) |
407 (1 << PS_CALLINC_SHIFT);
408 } else {
409 base = 0;
410 regs->areg[base] = (unsigned long) ra;
411 }
412 regs->areg[base + 2] = (unsigned long) sig;
413 regs->areg[base + 3] = (unsigned long) &frame->info;
414 regs->areg[base + 4] = (unsigned long) &frame->uc;
415 regs->threadptr = tp;
416 regs->ps = ps;
417
418 pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n",
419 current->comm, current->pid, sig, frame, regs->pc);
420
421 return 0;
422 }
423
424 /*
425 * Note that 'init' is a special process: it doesn't get signals it doesn't
426 * want to handle. Thus you cannot kill init even with a SIGKILL even by
427 * mistake.
428 *
429 * Note that we go through the signals twice: once to check the signals that
430 * the kernel can handle, and then we build all the user-level signal handling
431 * stack-frames in one go after that.
432 */
do_signal(struct pt_regs * regs)433 static void do_signal(struct pt_regs *regs)
434 {
435 struct ksignal ksig;
436
437 task_pt_regs(current)->icountlevel = 0;
438
439 if (get_signal(&ksig)) {
440 int ret;
441
442 /* Are we from a system call? */
443
444 if (regs->syscall != NO_SYSCALL) {
445
446 /* If so, check system call restarting.. */
447
448 switch (regs->areg[2]) {
449 case -ERESTARTNOHAND:
450 case -ERESTART_RESTARTBLOCK:
451 regs->areg[2] = -EINTR;
452 break;
453
454 case -ERESTARTSYS:
455 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
456 regs->areg[2] = -EINTR;
457 break;
458 }
459 fallthrough;
460 case -ERESTARTNOINTR:
461 regs->areg[2] = regs->syscall;
462 regs->pc -= 3;
463 break;
464
465 default:
466 /* nothing to do */
467 if (regs->areg[2] != 0)
468 break;
469 }
470 }
471
472 /* Whee! Actually deliver the signal. */
473 /* Set up the stack frame */
474 ret = setup_frame(&ksig, sigmask_to_save(), regs);
475 signal_setup_done(ret, &ksig, 0);
476 if (current->ptrace & PT_SINGLESTEP)
477 task_pt_regs(current)->icountlevel = 1;
478
479 return;
480 }
481
482 /* Did we come from a system call? */
483 if (regs->syscall != NO_SYSCALL) {
484 /* Restart the system call - no handlers present */
485 switch (regs->areg[2]) {
486 case -ERESTARTNOHAND:
487 case -ERESTARTSYS:
488 case -ERESTARTNOINTR:
489 regs->areg[2] = regs->syscall;
490 regs->pc -= 3;
491 break;
492 case -ERESTART_RESTARTBLOCK:
493 regs->areg[2] = __NR_restart_syscall;
494 regs->pc -= 3;
495 break;
496 }
497 }
498
499 /* If there's no signal to deliver, we just restore the saved mask. */
500 restore_saved_sigmask();
501
502 if (current->ptrace & PT_SINGLESTEP)
503 task_pt_regs(current)->icountlevel = 1;
504 return;
505 }
506
do_notify_resume(struct pt_regs * regs)507 void do_notify_resume(struct pt_regs *regs)
508 {
509 if (test_thread_flag(TIF_SIGPENDING) ||
510 test_thread_flag(TIF_NOTIFY_SIGNAL))
511 do_signal(regs);
512
513 if (test_thread_flag(TIF_NOTIFY_RESUME))
514 tracehook_notify_resume(regs);
515 }
516