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TOMOYO Linux Cross Reference
Linux/arch/mips/kernel/signal.c

Version: ~ [ linux-5.9-rc6 ] ~ [ linux-5.8.10 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.66 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.146 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.198 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.236 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.236 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

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