1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/arch/alpha/kernel/signal.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 */
9
10 #include <linux/sched/signal.h>
11 #include <linux/sched/task_stack.h>
12 #include <linux/kernel.h>
13 #include <linux/signal.h>
14 #include <linux/errno.h>
15 #include <linux/wait.h>
16 #include <linux/ptrace.h>
17 #include <linux/unistd.h>
18 #include <linux/mm.h>
19 #include <linux/smp.h>
20 #include <linux/stddef.h>
21 #include <linux/tty.h>
22 #include <linux/binfmts.h>
23 #include <linux/bitops.h>
24 #include <linux/syscalls.h>
25 #include <linux/resume_user_mode.h>
26
27 #include <linux/uaccess.h>
28 #include <asm/sigcontext.h>
29 #include <asm/ucontext.h>
30
31 #include "proto.h"
32
33
34 #define DEBUG_SIG 0
35
36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
37
38 asmlinkage void ret_from_sys_call(void);
39
40 /*
41 * The OSF/1 sigprocmask calling sequence is different from the
42 * C sigprocmask() sequence..
43 */
44 SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
45 {
46 sigset_t oldmask;
47 sigset_t mask;
48 unsigned long res;
49
50 siginitset(&mask, newmask & _BLOCKABLE);
51 res = sigprocmask(how, &mask, &oldmask);
52 if (!res) {
53 force_successful_syscall_return();
54 res = oldmask.sig[0];
55 }
56 return res;
57 }
58
59 SYSCALL_DEFINE3(osf_sigaction, int, sig,
60 const struct osf_sigaction __user *, act,
61 struct osf_sigaction __user *, oact)
62 {
63 struct k_sigaction new_ka, old_ka;
64 int ret;
65
66 if (act) {
67 old_sigset_t mask;
68 if (!access_ok(act, sizeof(*act)) ||
69 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
70 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
71 __get_user(mask, &act->sa_mask))
72 return -EFAULT;
73 siginitset(&new_ka.sa.sa_mask, mask);
74 new_ka.ka_restorer = NULL;
75 }
76
77 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
78
79 if (!ret && oact) {
80 if (!access_ok(oact, sizeof(*oact)) ||
81 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
82 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
83 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
84 return -EFAULT;
85 }
86
87 return ret;
88 }
89
90 SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
91 struct sigaction __user *, oact,
92 size_t, sigsetsize, void __user *, restorer)
93 {
94 struct k_sigaction new_ka, old_ka;
95 int ret;
96
97 /* XXX: Don't preclude handling different sized sigset_t's. */
98 if (sigsetsize != sizeof(sigset_t))
99 return -EINVAL;
100
101 if (act) {
102 new_ka.ka_restorer = restorer;
103 if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
104 return -EFAULT;
105 }
106
107 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
108
109 if (!ret && oact) {
110 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
111 return -EFAULT;
112 }
113
114 return ret;
115 }
116
117 /*
118 * Do a signal return; undo the signal stack.
119 */
120
121 #if _NSIG_WORDS > 1
122 # error "Non SA_SIGINFO frame needs rearranging"
123 #endif
124
125 struct sigframe
126 {
127 struct sigcontext sc;
128 unsigned int retcode[3];
129 };
130
131 struct rt_sigframe
132 {
133 struct siginfo info;
134 struct ucontext uc;
135 unsigned int retcode[3];
136 };
137
138 /* If this changes, userland unwinders that Know Things about our signal
139 frame will break. Do not undertake lightly. It also implies an ABI
140 change wrt the size of siginfo_t, which may cause some pain. */
141 extern char compile_time_assert
142 [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
143
144 #define INSN_MOV_R30_R16 0x47fe0410
145 #define INSN_LDI_R0 0x201f0000
146 #define INSN_CALLSYS 0x00000083
147
148 static long
149 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
150 {
151 unsigned long usp;
152 struct switch_stack *sw = (struct switch_stack *)regs - 1;
153 long err = __get_user(regs->pc, &sc->sc_pc);
154
155 current->restart_block.fn = do_no_restart_syscall;
156 current_thread_info()->status |= TS_SAVED_FP | TS_RESTORE_FP;
157
158 sw->r26 = (unsigned long) ret_from_sys_call;
159
160 err |= __get_user(regs->r0, sc->sc_regs+0);
161 err |= __get_user(regs->r1, sc->sc_regs+1);
162 err |= __get_user(regs->r2, sc->sc_regs+2);
163 err |= __get_user(regs->r3, sc->sc_regs+3);
164 err |= __get_user(regs->r4, sc->sc_regs+4);
165 err |= __get_user(regs->r5, sc->sc_regs+5);
166 err |= __get_user(regs->r6, sc->sc_regs+6);
167 err |= __get_user(regs->r7, sc->sc_regs+7);
168 err |= __get_user(regs->r8, sc->sc_regs+8);
169 err |= __get_user(sw->r9, sc->sc_regs+9);
170 err |= __get_user(sw->r10, sc->sc_regs+10);
171 err |= __get_user(sw->r11, sc->sc_regs+11);
172 err |= __get_user(sw->r12, sc->sc_regs+12);
173 err |= __get_user(sw->r13, sc->sc_regs+13);
174 err |= __get_user(sw->r14, sc->sc_regs+14);
175 err |= __get_user(sw->r15, sc->sc_regs+15);
176 err |= __get_user(regs->r16, sc->sc_regs+16);
177 err |= __get_user(regs->r17, sc->sc_regs+17);
178 err |= __get_user(regs->r18, sc->sc_regs+18);
179 err |= __get_user(regs->r19, sc->sc_regs+19);
180 err |= __get_user(regs->r20, sc->sc_regs+20);
181 err |= __get_user(regs->r21, sc->sc_regs+21);
182 err |= __get_user(regs->r22, sc->sc_regs+22);
183 err |= __get_user(regs->r23, sc->sc_regs+23);
184 err |= __get_user(regs->r24, sc->sc_regs+24);
185 err |= __get_user(regs->r25, sc->sc_regs+25);
186 err |= __get_user(regs->r26, sc->sc_regs+26);
187 err |= __get_user(regs->r27, sc->sc_regs+27);
188 err |= __get_user(regs->r28, sc->sc_regs+28);
189 err |= __get_user(regs->gp, sc->sc_regs+29);
190 err |= __get_user(usp, sc->sc_regs+30);
191 wrusp(usp);
192
193 err |= __copy_from_user(current_thread_info()->fp,
194 sc->sc_fpregs, 31 * 8);
195 err |= __get_user(current_thread_info()->fp[31], &sc->sc_fpcr);
196
197 return err;
198 }
199
200 /* Note that this syscall is also used by setcontext(3) to install
201 a given sigcontext. This because it's impossible to set *all*
202 registers and transfer control from userland. */
203
204 asmlinkage void
205 do_sigreturn(struct sigcontext __user *sc)
206 {
207 struct pt_regs *regs = current_pt_regs();
208 sigset_t set;
209
210 /* Verify that it's a good sigcontext before using it */
211 if (!access_ok(sc, sizeof(*sc)))
212 goto give_sigsegv;
213 if (__get_user(set.sig[0], &sc->sc_mask))
214 goto give_sigsegv;
215
216 set_current_blocked(&set);
217
218 if (restore_sigcontext(sc, regs))
219 goto give_sigsegv;
220
221 /* Send SIGTRAP if we're single-stepping: */
222 if (ptrace_cancel_bpt (current)) {
223 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
224 current);
225 }
226 return;
227
228 give_sigsegv:
229 force_sig(SIGSEGV);
230 }
231
232 asmlinkage void
233 do_rt_sigreturn(struct rt_sigframe __user *frame)
234 {
235 struct pt_regs *regs = current_pt_regs();
236 sigset_t set;
237
238 /* Verify that it's a good ucontext_t before using it */
239 if (!access_ok(&frame->uc, sizeof(frame->uc)))
240 goto give_sigsegv;
241 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
242 goto give_sigsegv;
243
244 set_current_blocked(&set);
245
246 if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
247 goto give_sigsegv;
248
249 /* Send SIGTRAP if we're single-stepping: */
250 if (ptrace_cancel_bpt (current)) {
251 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
252 current);
253 }
254 return;
255
256 give_sigsegv:
257 force_sig(SIGSEGV);
258 }
259
260
261 /*
262 * Set up a signal frame.
263 */
264
265 static inline void __user *
266 get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
267 {
268 return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
269 }
270
271 static long
272 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
273 unsigned long mask, unsigned long sp)
274 {
275 struct switch_stack *sw = (struct switch_stack *)regs - 1;
276 long err = 0;
277
278 err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
279 err |= __put_user(mask, &sc->sc_mask);
280 err |= __put_user(regs->pc, &sc->sc_pc);
281 err |= __put_user(8, &sc->sc_ps);
282
283 err |= __put_user(regs->r0 , sc->sc_regs+0);
284 err |= __put_user(regs->r1 , sc->sc_regs+1);
285 err |= __put_user(regs->r2 , sc->sc_regs+2);
286 err |= __put_user(regs->r3 , sc->sc_regs+3);
287 err |= __put_user(regs->r4 , sc->sc_regs+4);
288 err |= __put_user(regs->r5 , sc->sc_regs+5);
289 err |= __put_user(regs->r6 , sc->sc_regs+6);
290 err |= __put_user(regs->r7 , sc->sc_regs+7);
291 err |= __put_user(regs->r8 , sc->sc_regs+8);
292 err |= __put_user(sw->r9 , sc->sc_regs+9);
293 err |= __put_user(sw->r10 , sc->sc_regs+10);
294 err |= __put_user(sw->r11 , sc->sc_regs+11);
295 err |= __put_user(sw->r12 , sc->sc_regs+12);
296 err |= __put_user(sw->r13 , sc->sc_regs+13);
297 err |= __put_user(sw->r14 , sc->sc_regs+14);
298 err |= __put_user(sw->r15 , sc->sc_regs+15);
299 err |= __put_user(regs->r16, sc->sc_regs+16);
300 err |= __put_user(regs->r17, sc->sc_regs+17);
301 err |= __put_user(regs->r18, sc->sc_regs+18);
302 err |= __put_user(regs->r19, sc->sc_regs+19);
303 err |= __put_user(regs->r20, sc->sc_regs+20);
304 err |= __put_user(regs->r21, sc->sc_regs+21);
305 err |= __put_user(regs->r22, sc->sc_regs+22);
306 err |= __put_user(regs->r23, sc->sc_regs+23);
307 err |= __put_user(regs->r24, sc->sc_regs+24);
308 err |= __put_user(regs->r25, sc->sc_regs+25);
309 err |= __put_user(regs->r26, sc->sc_regs+26);
310 err |= __put_user(regs->r27, sc->sc_regs+27);
311 err |= __put_user(regs->r28, sc->sc_regs+28);
312 err |= __put_user(regs->gp , sc->sc_regs+29);
313 err |= __put_user(sp, sc->sc_regs+30);
314 err |= __put_user(0, sc->sc_regs+31);
315
316 err |= __copy_to_user(sc->sc_fpregs,
317 current_thread_info()->fp, 31 * 8);
318 err |= __put_user(0, sc->sc_fpregs+31);
319 err |= __put_user(current_thread_info()->fp[31], &sc->sc_fpcr);
320
321 err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
322 err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
323 err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
324
325 return err;
326 }
327
328 static int
329 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
330 {
331 unsigned long oldsp, r26, err = 0;
332 struct sigframe __user *frame;
333
334 oldsp = rdusp();
335 frame = get_sigframe(ksig, oldsp, sizeof(*frame));
336 if (!access_ok(frame, sizeof(*frame)))
337 return -EFAULT;
338
339 err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
340 if (err)
341 return -EFAULT;
342
343 /* Set up to return from userspace. If provided, use a stub
344 already in userspace. */
345 r26 = (unsigned long) ksig->ka.ka_restorer;
346 if (!r26) {
347 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
348 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
349 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
350 imb();
351 r26 = (unsigned long) frame->retcode;
352 }
353
354 /* Check that everything was written properly. */
355 if (err)
356 return err;
357
358 /* "Return" to the handler */
359 regs->r26 = r26;
360 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
361 regs->r16 = ksig->sig; /* a0: signal number */
362 regs->r17 = 0; /* a1: exception code */
363 regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
364 wrusp((unsigned long) frame);
365
366 #if DEBUG_SIG
367 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
368 current->comm, current->pid, frame, regs->pc, regs->r26);
369 #endif
370 return 0;
371 }
372
373 static int
374 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
375 {
376 unsigned long oldsp, r26, err = 0;
377 struct rt_sigframe __user *frame;
378
379 oldsp = rdusp();
380 frame = get_sigframe(ksig, oldsp, sizeof(*frame));
381 if (!access_ok(frame, sizeof(*frame)))
382 return -EFAULT;
383
384 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
385
386 /* Create the ucontext. */
387 err |= __put_user(0, &frame->uc.uc_flags);
388 err |= __put_user(0, &frame->uc.uc_link);
389 err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
390 err |= __save_altstack(&frame->uc.uc_stack, oldsp);
391 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
392 set->sig[0], oldsp);
393 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
394 if (err)
395 return -EFAULT;
396
397 /* Set up to return from userspace. If provided, use a stub
398 already in userspace. */
399 r26 = (unsigned long) ksig->ka.ka_restorer;
400 if (!r26) {
401 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
402 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
403 frame->retcode+1);
404 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
405 imb();
406 r26 = (unsigned long) frame->retcode;
407 }
408
409 if (err)
410 return -EFAULT;
411
412 /* "Return" to the handler */
413 regs->r26 = r26;
414 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
415 regs->r16 = ksig->sig; /* a0: signal number */
416 regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
417 regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */
418 wrusp((unsigned long) frame);
419
420 #if DEBUG_SIG
421 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
422 current->comm, current->pid, frame, regs->pc, regs->r26);
423 #endif
424
425 return 0;
426 }
427
428
429 /*
430 * OK, we're invoking a handler.
431 */
432 static inline void
433 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
434 {
435 sigset_t *oldset = sigmask_to_save();
436 int ret;
437
438 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
439 ret = setup_rt_frame(ksig, oldset, regs);
440 else
441 ret = setup_frame(ksig, oldset, regs);
442
443 signal_setup_done(ret, ksig, 0);
444 }
445
446 static inline void
447 syscall_restart(unsigned long r0, unsigned long r19,
448 struct pt_regs *regs, struct k_sigaction *ka)
449 {
450 switch (regs->r0) {
451 case ERESTARTSYS:
452 if (!(ka->sa.sa_flags & SA_RESTART)) {
453 case ERESTARTNOHAND:
454 regs->r0 = EINTR;
455 break;
456 }
457 fallthrough;
458 case ERESTARTNOINTR:
459 regs->r0 = r0; /* reset v0 and a3 and replay syscall */
460 regs->r19 = r19;
461 regs->pc -= 4;
462 break;
463 case ERESTART_RESTARTBLOCK:
464 regs->r0 = EINTR;
465 break;
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 *
479 * "r0" and "r19" are the registers we need to restore for system call
480 * restart. "r0" is also used as an indicator whether we can restart at
481 * all (if we get here from anything but a syscall return, it will be 0)
482 */
483 static void
484 do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
485 {
486 unsigned long single_stepping = ptrace_cancel_bpt(current);
487 struct ksignal ksig;
488
489 /* This lets the debugger run, ... */
490 if (get_signal(&ksig)) {
491 /* ... so re-check the single stepping. */
492 single_stepping |= ptrace_cancel_bpt(current);
493 /* Whee! Actually deliver the signal. */
494 if (r0)
495 syscall_restart(r0, r19, regs, &ksig.ka);
496 handle_signal(&ksig, regs);
497 } else {
498 single_stepping |= ptrace_cancel_bpt(current);
499 if (r0) {
500 switch (regs->r0) {
501 case ERESTARTNOHAND:
502 case ERESTARTSYS:
503 case ERESTARTNOINTR:
504 /* Reset v0 and a3 and replay syscall. */
505 regs->r0 = r0;
506 regs->r19 = r19;
507 regs->pc -= 4;
508 break;
509 case ERESTART_RESTARTBLOCK:
510 /* Set v0 to the restart_syscall and replay */
511 regs->r0 = __NR_restart_syscall;
512 regs->pc -= 4;
513 break;
514 }
515 }
516 restore_saved_sigmask();
517 }
518 if (single_stepping)
519 ptrace_set_bpt(current); /* re-set breakpoint */
520 }
521
522 void
523 do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
524 unsigned long r0, unsigned long r19)
525 {
526 do {
527 if (thread_flags & _TIF_NEED_RESCHED) {
528 schedule();
529 } else {
530 local_irq_enable();
531 if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) {
532 preempt_disable();
533 save_fpu();
534 preempt_enable();
535 do_signal(regs, r0, r19);
536 r0 = 0;
537 } else {
538 resume_user_mode_work(regs);
539 }
540 }
541 local_irq_disable();
542 thread_flags = read_thread_flags();
543 } while (thread_flags & _TIF_WORK_MASK);
544 }
545
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