xref: /openbmc/linux/arch/mips/kernel/signal.c (revision 03248add)
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 1991, 1992  Linus Torvalds
7  * Copyright (C) 1994 - 2000  Ralf Baechle
8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
9  * Copyright (C) 2014, Imagination Technologies Ltd.
10  */
11 #include <linux/cache.h>
12 #include <linux/context_tracking.h>
13 #include <linux/irqflags.h>
14 #include <linux/sched.h>
15 #include <linux/mm.h>
16 #include <linux/personality.h>
17 #include <linux/smp.h>
18 #include <linux/kernel.h>
19 #include <linux/signal.h>
20 #include <linux/errno.h>
21 #include <linux/wait.h>
22 #include <linux/ptrace.h>
23 #include <linux/unistd.h>
24 #include <linux/uprobes.h>
25 #include <linux/compiler.h>
26 #include <linux/syscalls.h>
27 #include <linux/uaccess.h>
28 #include <linux/resume_user_mode.h>
29 
30 #include <asm/abi.h>
31 #include <asm/asm.h>
32 #include <linux/bitops.h>
33 #include <asm/cacheflush.h>
34 #include <asm/fpu.h>
35 #include <asm/sim.h>
36 #include <asm/ucontext.h>
37 #include <asm/cpu-features.h>
38 #include <asm/dsp.h>
39 #include <asm/inst.h>
40 #include <asm/msa.h>
41 
42 #include "signal-common.h"
43 
44 static int (*save_fp_context)(void __user *sc);
45 static int (*restore_fp_context)(void __user *sc);
46 
47 struct sigframe {
48 	u32 sf_ass[4];		/* argument save space for o32 */
49 	u32 sf_pad[2];		/* Was: signal trampoline */
50 
51 	/* Matches struct ucontext from its uc_mcontext field onwards */
52 	struct sigcontext sf_sc;
53 	sigset_t sf_mask;
54 	unsigned long long sf_extcontext[];
55 };
56 
57 struct rt_sigframe {
58 	u32 rs_ass[4];		/* argument save space for o32 */
59 	u32 rs_pad[2];		/* Was: signal trampoline */
60 	struct siginfo rs_info;
61 	struct ucontext rs_uc;
62 };
63 
64 #ifdef CONFIG_MIPS_FP_SUPPORT
65 
66 /*
67  * Thread saved context copy to/from a signal context presumed to be on the
68  * user stack, and therefore accessed with appropriate macros from uaccess.h.
69  */
copy_fp_to_sigcontext(void __user * sc)70 static int copy_fp_to_sigcontext(void __user *sc)
71 {
72 	struct mips_abi *abi = current->thread.abi;
73 	uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
74 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
75 	int i;
76 	int err = 0;
77 	int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
78 
79 	for (i = 0; i < NUM_FPU_REGS; i += inc) {
80 		err |=
81 		    __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
82 			       &fpregs[i]);
83 	}
84 	err |= __put_user(current->thread.fpu.fcr31, csr);
85 
86 	return err;
87 }
88 
copy_fp_from_sigcontext(void __user * sc)89 static int copy_fp_from_sigcontext(void __user *sc)
90 {
91 	struct mips_abi *abi = current->thread.abi;
92 	uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
93 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
94 	int i;
95 	int err = 0;
96 	int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
97 	u64 fpr_val;
98 
99 	for (i = 0; i < NUM_FPU_REGS; i += inc) {
100 		err |= __get_user(fpr_val, &fpregs[i]);
101 		set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
102 	}
103 	err |= __get_user(current->thread.fpu.fcr31, csr);
104 
105 	return err;
106 }
107 
108 #else /* !CONFIG_MIPS_FP_SUPPORT */
109 
copy_fp_to_sigcontext(void __user * sc)110 static int copy_fp_to_sigcontext(void __user *sc)
111 {
112 	return 0;
113 }
114 
copy_fp_from_sigcontext(void __user * sc)115 static int copy_fp_from_sigcontext(void __user *sc)
116 {
117 	return 0;
118 }
119 
120 #endif /* !CONFIG_MIPS_FP_SUPPORT */
121 
122 /*
123  * Wrappers for the assembly _{save,restore}_fp_context functions.
124  */
save_hw_fp_context(void __user * sc)125 static int save_hw_fp_context(void __user *sc)
126 {
127 	struct mips_abi *abi = current->thread.abi;
128 	uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
129 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
130 
131 	return _save_fp_context(fpregs, csr);
132 }
133 
restore_hw_fp_context(void __user * sc)134 static int restore_hw_fp_context(void __user *sc)
135 {
136 	struct mips_abi *abi = current->thread.abi;
137 	uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
138 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
139 
140 	return _restore_fp_context(fpregs, csr);
141 }
142 
143 /*
144  * Extended context handling.
145  */
146 
sc_to_extcontext(void __user * sc)147 static inline void __user *sc_to_extcontext(void __user *sc)
148 {
149 	struct ucontext __user *uc;
150 
151 	/*
152 	 * We can just pretend the sigcontext is always embedded in a struct
153 	 * ucontext here, because the offset from sigcontext to extended
154 	 * context is the same in the struct sigframe case.
155 	 */
156 	uc = container_of(sc, struct ucontext, uc_mcontext);
157 	return &uc->uc_extcontext;
158 }
159 
160 #ifdef CONFIG_CPU_HAS_MSA
161 
save_msa_extcontext(void __user * buf)162 static int save_msa_extcontext(void __user *buf)
163 {
164 	struct msa_extcontext __user *msa = buf;
165 	uint64_t val;
166 	int i, err;
167 
168 	if (!thread_msa_context_live())
169 		return 0;
170 
171 	/*
172 	 * Ensure that we can't lose the live MSA context between checking
173 	 * for it & writing it to memory.
174 	 */
175 	preempt_disable();
176 
177 	if (is_msa_enabled()) {
178 		/*
179 		 * There are no EVA versions of the vector register load/store
180 		 * instructions, so MSA context has to be saved to kernel memory
181 		 * and then copied to user memory. The save to kernel memory
182 		 * should already have been done when handling scalar FP
183 		 * context.
184 		 */
185 		BUG_ON(IS_ENABLED(CONFIG_EVA));
186 
187 		err = __put_user(read_msa_csr(), &msa->csr);
188 		err |= _save_msa_all_upper(&msa->wr);
189 
190 		preempt_enable();
191 	} else {
192 		preempt_enable();
193 
194 		err = __put_user(current->thread.fpu.msacsr, &msa->csr);
195 
196 		for (i = 0; i < NUM_FPU_REGS; i++) {
197 			val = get_fpr64(&current->thread.fpu.fpr[i], 1);
198 			err |= __put_user(val, &msa->wr[i]);
199 		}
200 	}
201 
202 	err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic);
203 	err |= __put_user(sizeof(*msa), &msa->ext.size);
204 
205 	return err ? -EFAULT : sizeof(*msa);
206 }
207 
restore_msa_extcontext(void __user * buf,unsigned int size)208 static int restore_msa_extcontext(void __user *buf, unsigned int size)
209 {
210 	struct msa_extcontext __user *msa = buf;
211 	unsigned long long val;
212 	unsigned int csr;
213 	int i, err;
214 
215 	if (size != sizeof(*msa))
216 		return -EINVAL;
217 
218 	err = get_user(csr, &msa->csr);
219 	if (err)
220 		return err;
221 
222 	preempt_disable();
223 
224 	if (is_msa_enabled()) {
225 		/*
226 		 * There are no EVA versions of the vector register load/store
227 		 * instructions, so MSA context has to be copied to kernel
228 		 * memory and later loaded to registers. The same is true of
229 		 * scalar FP context, so FPU & MSA should have already been
230 		 * disabled whilst handling scalar FP context.
231 		 */
232 		BUG_ON(IS_ENABLED(CONFIG_EVA));
233 
234 		write_msa_csr(csr);
235 		err |= _restore_msa_all_upper(&msa->wr);
236 		preempt_enable();
237 	} else {
238 		preempt_enable();
239 
240 		current->thread.fpu.msacsr = csr;
241 
242 		for (i = 0; i < NUM_FPU_REGS; i++) {
243 			err |= __get_user(val, &msa->wr[i]);
244 			set_fpr64(&current->thread.fpu.fpr[i], 1, val);
245 		}
246 	}
247 
248 	return err;
249 }
250 
251 #else /* !CONFIG_CPU_HAS_MSA */
252 
save_msa_extcontext(void __user * buf)253 static int save_msa_extcontext(void __user *buf)
254 {
255 	return 0;
256 }
257 
restore_msa_extcontext(void __user * buf,unsigned int size)258 static int restore_msa_extcontext(void __user *buf, unsigned int size)
259 {
260 	return SIGSYS;
261 }
262 
263 #endif /* !CONFIG_CPU_HAS_MSA */
264 
save_extcontext(void __user * buf)265 static int save_extcontext(void __user *buf)
266 {
267 	int sz;
268 
269 	sz = save_msa_extcontext(buf);
270 	if (sz < 0)
271 		return sz;
272 	buf += sz;
273 
274 	/* If no context was saved then trivially return */
275 	if (!sz)
276 		return 0;
277 
278 	/* Write the end marker */
279 	if (__put_user(END_EXTCONTEXT_MAGIC, (u32 *)buf))
280 		return -EFAULT;
281 
282 	sz += sizeof(((struct extcontext *)NULL)->magic);
283 	return sz;
284 }
285 
restore_extcontext(void __user * buf)286 static int restore_extcontext(void __user *buf)
287 {
288 	struct extcontext ext;
289 	int err;
290 
291 	while (1) {
292 		err = __get_user(ext.magic, (unsigned int *)buf);
293 		if (err)
294 			return err;
295 
296 		if (ext.magic == END_EXTCONTEXT_MAGIC)
297 			return 0;
298 
299 		err = __get_user(ext.size, (unsigned int *)(buf
300 			+ offsetof(struct extcontext, size)));
301 		if (err)
302 			return err;
303 
304 		switch (ext.magic) {
305 		case MSA_EXTCONTEXT_MAGIC:
306 			err = restore_msa_extcontext(buf, ext.size);
307 			break;
308 
309 		default:
310 			err = -EINVAL;
311 			break;
312 		}
313 
314 		if (err)
315 			return err;
316 
317 		buf += ext.size;
318 	}
319 }
320 
321 /*
322  * Helper routines
323  */
protected_save_fp_context(void __user * sc)324 int protected_save_fp_context(void __user *sc)
325 {
326 	struct mips_abi *abi = current->thread.abi;
327 	uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
328 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
329 	uint32_t __user *used_math = sc + abi->off_sc_used_math;
330 	unsigned int used, ext_sz;
331 	int err;
332 
333 	used = used_math() ? USED_FP : 0;
334 	if (!used)
335 		goto fp_done;
336 
337 	if (!test_thread_flag(TIF_32BIT_FPREGS))
338 		used |= USED_FR1;
339 	if (test_thread_flag(TIF_HYBRID_FPREGS))
340 		used |= USED_HYBRID_FPRS;
341 
342 	/*
343 	 * EVA does not have userland equivalents of ldc1 or sdc1, so
344 	 * save to the kernel FP context & copy that to userland below.
345 	 */
346 	if (IS_ENABLED(CONFIG_EVA))
347 		lose_fpu(1);
348 
349 	while (1) {
350 		lock_fpu_owner();
351 		if (is_fpu_owner()) {
352 			err = save_fp_context(sc);
353 			unlock_fpu_owner();
354 		} else {
355 			unlock_fpu_owner();
356 			err = copy_fp_to_sigcontext(sc);
357 		}
358 		if (likely(!err))
359 			break;
360 		/* touch the sigcontext and try again */
361 		err = __put_user(0, &fpregs[0]) |
362 			__put_user(0, &fpregs[31]) |
363 			__put_user(0, csr);
364 		if (err)
365 			return err;	/* really bad sigcontext */
366 	}
367 
368 fp_done:
369 	ext_sz = err = save_extcontext(sc_to_extcontext(sc));
370 	if (err < 0)
371 		return err;
372 	used |= ext_sz ? USED_EXTCONTEXT : 0;
373 
374 	return __put_user(used, used_math);
375 }
376 
protected_restore_fp_context(void __user * sc)377 int protected_restore_fp_context(void __user *sc)
378 {
379 	struct mips_abi *abi = current->thread.abi;
380 	uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
381 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
382 	uint32_t __user *used_math = sc + abi->off_sc_used_math;
383 	unsigned int used;
384 	int err, sig = 0, tmp __maybe_unused;
385 
386 	err = __get_user(used, used_math);
387 	conditional_used_math(used & USED_FP);
388 
389 	/*
390 	 * The signal handler may have used FPU; give it up if the program
391 	 * doesn't want it following sigreturn.
392 	 */
393 	if (err || !(used & USED_FP))
394 		lose_fpu(0);
395 	if (err)
396 		return err;
397 	if (!(used & USED_FP))
398 		goto fp_done;
399 
400 	err = sig = fpcsr_pending(csr);
401 	if (err < 0)
402 		return err;
403 
404 	/*
405 	 * EVA does not have userland equivalents of ldc1 or sdc1, so we
406 	 * disable the FPU here such that the code below simply copies to
407 	 * the kernel FP context.
408 	 */
409 	if (IS_ENABLED(CONFIG_EVA))
410 		lose_fpu(0);
411 
412 	while (1) {
413 		lock_fpu_owner();
414 		if (is_fpu_owner()) {
415 			err = restore_fp_context(sc);
416 			unlock_fpu_owner();
417 		} else {
418 			unlock_fpu_owner();
419 			err = copy_fp_from_sigcontext(sc);
420 		}
421 		if (likely(!err))
422 			break;
423 		/* touch the sigcontext and try again */
424 		err = __get_user(tmp, &fpregs[0]) |
425 			__get_user(tmp, &fpregs[31]) |
426 			__get_user(tmp, csr);
427 		if (err)
428 			break;	/* really bad sigcontext */
429 	}
430 
431 fp_done:
432 	if (!err && (used & USED_EXTCONTEXT))
433 		err = restore_extcontext(sc_to_extcontext(sc));
434 
435 	return err ?: sig;
436 }
437 
setup_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)438 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
439 {
440 	int err = 0;
441 	int i;
442 
443 	err |= __put_user(regs->cp0_epc, &sc->sc_pc);
444 
445 	err |= __put_user(0, &sc->sc_regs[0]);
446 	for (i = 1; i < 32; i++)
447 		err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
448 
449 #ifdef CONFIG_CPU_HAS_SMARTMIPS
450 	err |= __put_user(regs->acx, &sc->sc_acx);
451 #endif
452 	err |= __put_user(regs->hi, &sc->sc_mdhi);
453 	err |= __put_user(regs->lo, &sc->sc_mdlo);
454 	if (cpu_has_dsp) {
455 		err |= __put_user(mfhi1(), &sc->sc_hi1);
456 		err |= __put_user(mflo1(), &sc->sc_lo1);
457 		err |= __put_user(mfhi2(), &sc->sc_hi2);
458 		err |= __put_user(mflo2(), &sc->sc_lo2);
459 		err |= __put_user(mfhi3(), &sc->sc_hi3);
460 		err |= __put_user(mflo3(), &sc->sc_lo3);
461 		err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
462 	}
463 
464 
465 	/*
466 	 * Save FPU state to signal context. Signal handler
467 	 * will "inherit" current FPU state.
468 	 */
469 	err |= protected_save_fp_context(sc);
470 
471 	return err;
472 }
473 
extcontext_max_size(void)474 static size_t extcontext_max_size(void)
475 {
476 	size_t sz = 0;
477 
478 	/*
479 	 * The assumption here is that between this point & the point at which
480 	 * the extended context is saved the size of the context should only
481 	 * ever be able to shrink (if the task is preempted), but never grow.
482 	 * That is, what this function returns is an upper bound on the size of
483 	 * the extended context for the current task at the current time.
484 	 */
485 
486 	if (thread_msa_context_live())
487 		sz += sizeof(struct msa_extcontext);
488 
489 	/* If any context is saved then we'll append the end marker */
490 	if (sz)
491 		sz += sizeof(((struct extcontext *)NULL)->magic);
492 
493 	return sz;
494 }
495 
fpcsr_pending(unsigned int __user * fpcsr)496 int fpcsr_pending(unsigned int __user *fpcsr)
497 {
498 	int err, sig = 0;
499 	unsigned int csr, enabled;
500 
501 	err = __get_user(csr, fpcsr);
502 	enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
503 	/*
504 	 * If the signal handler set some FPU exceptions, clear it and
505 	 * send SIGFPE.
506 	 */
507 	if (csr & enabled) {
508 		csr &= ~enabled;
509 		err |= __put_user(csr, fpcsr);
510 		sig = SIGFPE;
511 	}
512 	return err ?: sig;
513 }
514 
restore_sigcontext(struct pt_regs * regs,struct sigcontext __user * sc)515 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
516 {
517 	unsigned long treg;
518 	int err = 0;
519 	int i;
520 
521 	/* Always make any pending restarted system calls return -EINTR */
522 	current->restart_block.fn = do_no_restart_syscall;
523 
524 	err |= __get_user(regs->cp0_epc, &sc->sc_pc);
525 
526 #ifdef CONFIG_CPU_HAS_SMARTMIPS
527 	err |= __get_user(regs->acx, &sc->sc_acx);
528 #endif
529 	err |= __get_user(regs->hi, &sc->sc_mdhi);
530 	err |= __get_user(regs->lo, &sc->sc_mdlo);
531 	if (cpu_has_dsp) {
532 		err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
533 		err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
534 		err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
535 		err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
536 		err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
537 		err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
538 		err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
539 	}
540 
541 	for (i = 1; i < 32; i++)
542 		err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
543 
544 	return err ?: protected_restore_fp_context(sc);
545 }
546 
547 #ifdef CONFIG_WAR_ICACHE_REFILLS
548 #define SIGMASK		~(cpu_icache_line_size()-1)
549 #else
550 #define SIGMASK		ALMASK
551 #endif
552 
get_sigframe(struct ksignal * ksig,struct pt_regs * regs,size_t frame_size)553 void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
554 			  size_t frame_size)
555 {
556 	unsigned long sp;
557 
558 	/* Leave space for potential extended context */
559 	frame_size += extcontext_max_size();
560 
561 	/* Default to using normal stack */
562 	sp = regs->regs[29];
563 
564 	/*
565 	 * If we are on the alternate signal stack and would overflow it, don't.
566 	 * Return an always-bogus address instead so we will die with SIGSEGV.
567 	 */
568 	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
569 		return (void __user __force *)(-1UL);
570 
571 	/*
572 	 * FPU emulator may have it's own trampoline active just
573 	 * above the user stack, 16-bytes before the next lowest
574 	 * 16 byte boundary.  Try to avoid trashing it.
575 	 */
576 	sp -= 32;
577 
578 	sp = sigsp(sp, ksig);
579 
580 	return (void __user *)((sp - frame_size) & SIGMASK);
581 }
582 
583 /*
584  * Atomically swap in the new signal mask, and wait for a signal.
585  */
586 
587 #ifdef CONFIG_TRAD_SIGNALS
SYSCALL_DEFINE1(sigsuspend,sigset_t __user *,uset)588 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
589 {
590 	return sys_rt_sigsuspend(uset, sizeof(sigset_t));
591 }
592 #endif
593 
594 #ifdef CONFIG_TRAD_SIGNALS
SYSCALL_DEFINE3(sigaction,int,sig,const struct sigaction __user *,act,struct sigaction __user *,oact)595 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
596 	struct sigaction __user *, oact)
597 {
598 	struct k_sigaction new_ka, old_ka;
599 	int ret;
600 	int err = 0;
601 
602 	if (act) {
603 		old_sigset_t mask;
604 
605 		if (!access_ok(act, sizeof(*act)))
606 			return -EFAULT;
607 		err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
608 		err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
609 		err |= __get_user(mask, &act->sa_mask.sig[0]);
610 		if (err)
611 			return -EFAULT;
612 
613 		siginitset(&new_ka.sa.sa_mask, mask);
614 	}
615 
616 	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
617 
618 	if (!ret && oact) {
619 		if (!access_ok(oact, sizeof(*oact)))
620 			return -EFAULT;
621 		err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
622 		err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
623 		err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
624 		err |= __put_user(0, &oact->sa_mask.sig[1]);
625 		err |= __put_user(0, &oact->sa_mask.sig[2]);
626 		err |= __put_user(0, &oact->sa_mask.sig[3]);
627 		if (err)
628 			return -EFAULT;
629 	}
630 
631 	return ret;
632 }
633 #endif
634 
635 #ifdef CONFIG_TRAD_SIGNALS
sys_sigreturn(void)636 asmlinkage void sys_sigreturn(void)
637 {
638 	struct sigframe __user *frame;
639 	struct pt_regs *regs;
640 	sigset_t blocked;
641 	int sig;
642 
643 	regs = current_pt_regs();
644 	frame = (struct sigframe __user *)regs->regs[29];
645 	if (!access_ok(frame, sizeof(*frame)))
646 		goto badframe;
647 	if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
648 		goto badframe;
649 
650 	set_current_blocked(&blocked);
651 
652 	sig = restore_sigcontext(regs, &frame->sf_sc);
653 	if (sig < 0)
654 		goto badframe;
655 	else if (sig)
656 		force_sig(sig);
657 
658 	/*
659 	 * Don't let your children do this ...
660 	 */
661 	__asm__ __volatile__(
662 		"move\t$29, %0\n\t"
663 		"j\tsyscall_exit"
664 		: /* no outputs */
665 		: "r" (regs));
666 	/* Unreached */
667 
668 badframe:
669 	force_sig(SIGSEGV);
670 }
671 #endif /* CONFIG_TRAD_SIGNALS */
672 
sys_rt_sigreturn(void)673 asmlinkage void sys_rt_sigreturn(void)
674 {
675 	struct rt_sigframe __user *frame;
676 	struct pt_regs *regs;
677 	sigset_t set;
678 	int sig;
679 
680 	regs = current_pt_regs();
681 	frame = (struct rt_sigframe __user *)regs->regs[29];
682 	if (!access_ok(frame, sizeof(*frame)))
683 		goto badframe;
684 	if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
685 		goto badframe;
686 
687 	set_current_blocked(&set);
688 
689 	sig = restore_sigcontext(regs, &frame->rs_uc.uc_mcontext);
690 	if (sig < 0)
691 		goto badframe;
692 	else if (sig)
693 		force_sig(sig);
694 
695 	if (restore_altstack(&frame->rs_uc.uc_stack))
696 		goto badframe;
697 
698 	/*
699 	 * Don't let your children do this ...
700 	 */
701 	__asm__ __volatile__(
702 		"move\t$29, %0\n\t"
703 		"j\tsyscall_exit"
704 		: /* no outputs */
705 		: "r" (regs));
706 	/* Unreached */
707 
708 badframe:
709 	force_sig(SIGSEGV);
710 }
711 
712 #ifdef CONFIG_TRAD_SIGNALS
setup_frame(void * sig_return,struct ksignal * ksig,struct pt_regs * regs,sigset_t * set)713 static int setup_frame(void *sig_return, struct ksignal *ksig,
714 		       struct pt_regs *regs, sigset_t *set)
715 {
716 	struct sigframe __user *frame;
717 	int err = 0;
718 
719 	frame = get_sigframe(ksig, regs, sizeof(*frame));
720 	if (!access_ok(frame, sizeof (*frame)))
721 		return -EFAULT;
722 
723 	err |= setup_sigcontext(regs, &frame->sf_sc);
724 	err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
725 	if (err)
726 		return -EFAULT;
727 
728 	/*
729 	 * Arguments to signal handler:
730 	 *
731 	 *   a0 = signal number
732 	 *   a1 = 0 (should be cause)
733 	 *   a2 = pointer to struct sigcontext
734 	 *
735 	 * $25 and c0_epc point to the signal handler, $29 points to the
736 	 * struct sigframe.
737 	 */
738 	regs->regs[ 4] = ksig->sig;
739 	regs->regs[ 5] = 0;
740 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
741 	regs->regs[29] = (unsigned long) frame;
742 	regs->regs[31] = (unsigned long) sig_return;
743 	regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
744 
745 	DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
746 	       current->comm, current->pid,
747 	       frame, regs->cp0_epc, regs->regs[31]);
748 	return 0;
749 }
750 #endif
751 
setup_rt_frame(void * sig_return,struct ksignal * ksig,struct pt_regs * regs,sigset_t * set)752 static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
753 			  struct pt_regs *regs, sigset_t *set)
754 {
755 	struct rt_sigframe __user *frame;
756 
757 	frame = get_sigframe(ksig, regs, sizeof(*frame));
758 	if (!access_ok(frame, sizeof (*frame)))
759 		return -EFAULT;
760 
761 	/* Create siginfo.  */
762 	if (copy_siginfo_to_user(&frame->rs_info, &ksig->info))
763 		return -EFAULT;
764 
765 	/* Create the ucontext.	 */
766 	if (__put_user(0, &frame->rs_uc.uc_flags))
767 		return -EFAULT;
768 	if (__put_user(NULL, &frame->rs_uc.uc_link))
769 		return -EFAULT;
770 	if (__save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]))
771 		return -EFAULT;
772 	if (setup_sigcontext(regs, &frame->rs_uc.uc_mcontext))
773 		return -EFAULT;
774 	if (__copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set)))
775 		return -EFAULT;
776 
777 	/*
778 	 * Arguments to signal handler:
779 	 *
780 	 *   a0 = signal number
781 	 *   a1 = 0 (should be cause)
782 	 *   a2 = pointer to ucontext
783 	 *
784 	 * $25 and c0_epc point to the signal handler, $29 points to
785 	 * the struct rt_sigframe.
786 	 */
787 	regs->regs[ 4] = ksig->sig;
788 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
789 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
790 	regs->regs[29] = (unsigned long) frame;
791 	regs->regs[31] = (unsigned long) sig_return;
792 	regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
793 
794 	DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
795 	       current->comm, current->pid,
796 	       frame, regs->cp0_epc, regs->regs[31]);
797 
798 	return 0;
799 }
800 
801 struct mips_abi mips_abi = {
802 #ifdef CONFIG_TRAD_SIGNALS
803 	.setup_frame	= setup_frame,
804 #endif
805 	.setup_rt_frame = setup_rt_frame,
806 	.restart	= __NR_restart_syscall,
807 
808 	.off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
809 	.off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
810 	.off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
811 
812 	.vdso		= &vdso_image,
813 };
814 
handle_signal(struct ksignal * ksig,struct pt_regs * regs)815 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
816 {
817 	sigset_t *oldset = sigmask_to_save();
818 	int ret;
819 	struct mips_abi *abi = current->thread.abi;
820 	void *vdso = current->mm->context.vdso;
821 
822 	/*
823 	 * If we were emulating a delay slot instruction, exit that frame such
824 	 * that addresses in the sigframe are as expected for userland and we
825 	 * don't have a problem if we reuse the thread's frame for an
826 	 * instruction within the signal handler.
827 	 */
828 	dsemul_thread_rollback(regs);
829 
830 	if (regs->regs[0]) {
831 		switch(regs->regs[2]) {
832 		case ERESTART_RESTARTBLOCK:
833 		case ERESTARTNOHAND:
834 			regs->regs[2] = EINTR;
835 			break;
836 		case ERESTARTSYS:
837 			if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
838 				regs->regs[2] = EINTR;
839 				break;
840 			}
841 			fallthrough;
842 		case ERESTARTNOINTR:
843 			regs->regs[7] = regs->regs[26];
844 			regs->regs[2] = regs->regs[0];
845 			regs->cp0_epc -= 4;
846 		}
847 
848 		regs->regs[0] = 0;		/* Don't deal with this again.	*/
849 	}
850 
851 	rseq_signal_deliver(ksig, regs);
852 
853 	if (sig_uses_siginfo(&ksig->ka, abi))
854 		ret = abi->setup_rt_frame(vdso + abi->vdso->off_rt_sigreturn,
855 					  ksig, regs, oldset);
856 	else
857 		ret = abi->setup_frame(vdso + abi->vdso->off_sigreturn,
858 				       ksig, regs, oldset);
859 
860 	signal_setup_done(ret, ksig, 0);
861 }
862 
do_signal(struct pt_regs * regs)863 static void do_signal(struct pt_regs *regs)
864 {
865 	struct ksignal ksig;
866 
867 	if (get_signal(&ksig)) {
868 		/* Whee!  Actually deliver the signal.	*/
869 		handle_signal(&ksig, regs);
870 		return;
871 	}
872 
873 	if (regs->regs[0]) {
874 		switch (regs->regs[2]) {
875 		case ERESTARTNOHAND:
876 		case ERESTARTSYS:
877 		case ERESTARTNOINTR:
878 			regs->regs[2] = regs->regs[0];
879 			regs->regs[7] = regs->regs[26];
880 			regs->cp0_epc -= 4;
881 			break;
882 
883 		case ERESTART_RESTARTBLOCK:
884 			regs->regs[2] = current->thread.abi->restart;
885 			regs->regs[7] = regs->regs[26];
886 			regs->cp0_epc -= 4;
887 			break;
888 		}
889 		regs->regs[0] = 0;	/* Don't deal with this again.	*/
890 	}
891 
892 	/*
893 	 * If there's no signal to deliver, we just put the saved sigmask
894 	 * back
895 	 */
896 	restore_saved_sigmask();
897 }
898 
899 /*
900  * notification of userspace execution resumption
901  * - triggered by the TIF_WORK_MASK flags
902  */
do_notify_resume(struct pt_regs * regs,void * unused,__u32 thread_info_flags)903 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
904 	__u32 thread_info_flags)
905 {
906 	local_irq_enable();
907 
908 	user_exit();
909 
910 	if (thread_info_flags & _TIF_UPROBE)
911 		uprobe_notify_resume(regs);
912 
913 	/* deal with pending signal delivery */
914 	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
915 		do_signal(regs);
916 
917 	if (thread_info_flags & _TIF_NOTIFY_RESUME)
918 		resume_user_mode_work(regs);
919 
920 	user_enter();
921 }
922 
923 #if defined(CONFIG_SMP) && defined(CONFIG_MIPS_FP_SUPPORT)
smp_save_fp_context(void __user * sc)924 static int smp_save_fp_context(void __user *sc)
925 {
926 	return raw_cpu_has_fpu
927 	       ? save_hw_fp_context(sc)
928 	       : copy_fp_to_sigcontext(sc);
929 }
930 
smp_restore_fp_context(void __user * sc)931 static int smp_restore_fp_context(void __user *sc)
932 {
933 	return raw_cpu_has_fpu
934 	       ? restore_hw_fp_context(sc)
935 	       : copy_fp_from_sigcontext(sc);
936 }
937 #endif
938 
signal_setup(void)939 static int signal_setup(void)
940 {
941 	/*
942 	 * The offset from sigcontext to extended context should be the same
943 	 * regardless of the type of signal, such that userland can always know
944 	 * where to look if it wishes to find the extended context structures.
945 	 */
946 	BUILD_BUG_ON((offsetof(struct sigframe, sf_extcontext) -
947 		      offsetof(struct sigframe, sf_sc)) !=
948 		     (offsetof(struct rt_sigframe, rs_uc.uc_extcontext) -
949 		      offsetof(struct rt_sigframe, rs_uc.uc_mcontext)));
950 
951 #if defined(CONFIG_SMP) && defined(CONFIG_MIPS_FP_SUPPORT)
952 	/* For now just do the cpu_has_fpu check when the functions are invoked */
953 	save_fp_context = smp_save_fp_context;
954 	restore_fp_context = smp_restore_fp_context;
955 #else
956 	if (cpu_has_fpu) {
957 		save_fp_context = save_hw_fp_context;
958 		restore_fp_context = restore_hw_fp_context;
959 	} else {
960 		save_fp_context = copy_fp_to_sigcontext;
961 		restore_fp_context = copy_fp_from_sigcontext;
962 	}
963 #endif /* CONFIG_SMP */
964 
965 	return 0;
966 }
967 
968 arch_initcall(signal_setup);
969