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Linux/arch/x86/kernel/signal.c

  1 /*
  2  *  Copyright (C) 1991, 1992  Linus Torvalds
  3  *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
  4  *
  5  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  6  *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
  7  *  2000-2002   x86-64 support by Andi Kleen
  8  */
  9 #include <linux/sched.h>
 10 #include <linux/mm.h>
 11 #include <linux/smp.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/tracehook.h>
 18 #include <linux/unistd.h>
 19 #include <linux/stddef.h>
 20 #include <linux/personality.h>
 21 #include <linux/uaccess.h>
 22 #include <linux/user-return-notifier.h>
 23 
 24 #include <asm/processor.h>
 25 #include <asm/ucontext.h>
 26 #include <asm/i387.h>
 27 #include <asm/vdso.h>
 28 #include <asm/mce.h>
 29 
 30 #ifdef CONFIG_X86_64
 31 #include <asm/proto.h>
 32 #include <asm/ia32_unistd.h>
 33 #endif /* CONFIG_X86_64 */
 34 
 35 #include <asm/syscall.h>
 36 #include <asm/syscalls.h>
 37 
 38 #include <asm/sigframe.h>
 39 
 40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 41 
 42 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
 43                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
 44                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
 45                          X86_EFLAGS_CF)
 46 
 47 #ifdef CONFIG_X86_32
 48 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
 49 #else
 50 # define FIX_EFLAGS     __FIX_EFLAGS
 51 #endif
 52 
 53 #define COPY(x)                 do {                    \
 54         get_user_ex(regs->x, &sc->x);                   \
 55 } while (0)
 56 
 57 #define GET_SEG(seg)            ({                      \
 58         unsigned short tmp;                             \
 59         get_user_ex(tmp, &sc->seg);                     \
 60         tmp;                                            \
 61 })
 62 
 63 #define COPY_SEG(seg)           do {                    \
 64         regs->seg = GET_SEG(seg);                       \
 65 } while (0)
 66 
 67 #define COPY_SEG_CPL3(seg)      do {                    \
 68         regs->seg = GET_SEG(seg) | 3;                   \
 69 } while (0)
 70 
 71 static int
 72 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
 73                    unsigned long *pax)
 74 {
 75         void __user *buf;
 76         unsigned int tmpflags;
 77         unsigned int err = 0;
 78 
 79         /* Always make any pending restarted system calls return -EINTR */
 80         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 81 
 82         get_user_try {
 83 
 84 #ifdef CONFIG_X86_32
 85                 set_user_gs(regs, GET_SEG(gs));
 86                 COPY_SEG(fs);
 87                 COPY_SEG(es);
 88                 COPY_SEG(ds);
 89 #endif /* CONFIG_X86_32 */
 90 
 91                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 92                 COPY(dx); COPY(cx); COPY(ip);
 93 
 94 #ifdef CONFIG_X86_64
 95                 COPY(r8);
 96                 COPY(r9);
 97                 COPY(r10);
 98                 COPY(r11);
 99                 COPY(r12);
100                 COPY(r13);
101                 COPY(r14);
102                 COPY(r15);
103 #endif /* CONFIG_X86_64 */
104 
105 #ifdef CONFIG_X86_32
106                 COPY_SEG_CPL3(cs);
107                 COPY_SEG_CPL3(ss);
108 #else /* !CONFIG_X86_32 */
109                 /* Kernel saves and restores only the CS segment register on signals,
110                  * which is the bare minimum needed to allow mixed 32/64-bit code.
111                  * App's signal handler can save/restore other segments if needed. */
112                 COPY_SEG_CPL3(cs);
113 #endif /* CONFIG_X86_32 */
114 
115                 get_user_ex(tmpflags, &sc->flags);
116                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
117                 regs->orig_ax = -1;             /* disable syscall checks */
118 
119                 get_user_ex(buf, &sc->fpstate);
120                 err |= restore_i387_xstate(buf);
121 
122                 get_user_ex(*pax, &sc->ax);
123         } get_user_catch(err);
124 
125         return err;
126 }
127 
128 static int
129 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
130                  struct pt_regs *regs, unsigned long mask)
131 {
132         int err = 0;
133 
134         put_user_try {
135 
136 #ifdef CONFIG_X86_32
137                 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
138                 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
139                 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
140                 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
141 #endif /* CONFIG_X86_32 */
142 
143                 put_user_ex(regs->di, &sc->di);
144                 put_user_ex(regs->si, &sc->si);
145                 put_user_ex(regs->bp, &sc->bp);
146                 put_user_ex(regs->sp, &sc->sp);
147                 put_user_ex(regs->bx, &sc->bx);
148                 put_user_ex(regs->dx, &sc->dx);
149                 put_user_ex(regs->cx, &sc->cx);
150                 put_user_ex(regs->ax, &sc->ax);
151 #ifdef CONFIG_X86_64
152                 put_user_ex(regs->r8, &sc->r8);
153                 put_user_ex(regs->r9, &sc->r9);
154                 put_user_ex(regs->r10, &sc->r10);
155                 put_user_ex(regs->r11, &sc->r11);
156                 put_user_ex(regs->r12, &sc->r12);
157                 put_user_ex(regs->r13, &sc->r13);
158                 put_user_ex(regs->r14, &sc->r14);
159                 put_user_ex(regs->r15, &sc->r15);
160 #endif /* CONFIG_X86_64 */
161 
162                 put_user_ex(current->thread.trap_no, &sc->trapno);
163                 put_user_ex(current->thread.error_code, &sc->err);
164                 put_user_ex(regs->ip, &sc->ip);
165 #ifdef CONFIG_X86_32
166                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
167                 put_user_ex(regs->flags, &sc->flags);
168                 put_user_ex(regs->sp, &sc->sp_at_signal);
169                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
170 #else /* !CONFIG_X86_32 */
171                 put_user_ex(regs->flags, &sc->flags);
172                 put_user_ex(regs->cs, &sc->cs);
173                 put_user_ex(0, &sc->gs);
174                 put_user_ex(0, &sc->fs);
175 #endif /* CONFIG_X86_32 */
176 
177                 put_user_ex(fpstate, &sc->fpstate);
178 
179                 /* non-iBCS2 extensions.. */
180                 put_user_ex(mask, &sc->oldmask);
181                 put_user_ex(current->thread.cr2, &sc->cr2);
182         } put_user_catch(err);
183 
184         return err;
185 }
186 
187 /*
188  * Set up a signal frame.
189  */
190 
191 /*
192  * Determine which stack to use..
193  */
194 static unsigned long align_sigframe(unsigned long sp)
195 {
196 #ifdef CONFIG_X86_32
197         /*
198          * Align the stack pointer according to the i386 ABI,
199          * i.e. so that on function entry ((sp + 4) & 15) == 0.
200          */
201         sp = ((sp + 4) & -16ul) - 4;
202 #else /* !CONFIG_X86_32 */
203         sp = round_down(sp, 16) - 8;
204 #endif
205         return sp;
206 }
207 
208 static inline void __user *
209 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
210              void __user **fpstate)
211 {
212         /* Default to using normal stack */
213         unsigned long sp = regs->sp;
214         int onsigstack = on_sig_stack(sp);
215 
216 #ifdef CONFIG_X86_64
217         /* redzone */
218         sp -= 128;
219 #endif /* CONFIG_X86_64 */
220 
221         if (!onsigstack) {
222                 /* This is the X/Open sanctioned signal stack switching.  */
223                 if (ka->sa.sa_flags & SA_ONSTACK) {
224                         if (current->sas_ss_size)
225                                 sp = current->sas_ss_sp + current->sas_ss_size;
226                 } else {
227 #ifdef CONFIG_X86_32
228                         /* This is the legacy signal stack switching. */
229                         if ((regs->ss & 0xffff) != __USER_DS &&
230                                 !(ka->sa.sa_flags & SA_RESTORER) &&
231                                         ka->sa.sa_restorer)
232                                 sp = (unsigned long) ka->sa.sa_restorer;
233 #endif /* CONFIG_X86_32 */
234                 }
235         }
236 
237         if (used_math()) {
238                 sp -= sig_xstate_size;
239 #ifdef CONFIG_X86_64
240                 sp = round_down(sp, 64);
241 #endif /* CONFIG_X86_64 */
242                 *fpstate = (void __user *)sp;
243         }
244 
245         sp = align_sigframe(sp - frame_size);
246 
247         /*
248          * If we are on the alternate signal stack and would overflow it, don't.
249          * Return an always-bogus address instead so we will die with SIGSEGV.
250          */
251         if (onsigstack && !likely(on_sig_stack(sp)))
252                 return (void __user *)-1L;
253 
254         /* save i387 state */
255         if (used_math() && save_i387_xstate(*fpstate) < 0)
256                 return (void __user *)-1L;
257 
258         return (void __user *)sp;
259 }
260 
261 #ifdef CONFIG_X86_32
262 static const struct {
263         u16 poplmovl;
264         u32 val;
265         u16 int80;
266 } __attribute__((packed)) retcode = {
267         0xb858,         /* popl %eax; movl $..., %eax */
268         __NR_sigreturn,
269         0x80cd,         /* int $0x80 */
270 };
271 
272 static const struct {
273         u8  movl;
274         u32 val;
275         u16 int80;
276         u8  pad;
277 } __attribute__((packed)) rt_retcode = {
278         0xb8,           /* movl $..., %eax */
279         __NR_rt_sigreturn,
280         0x80cd,         /* int $0x80 */
281         0
282 };
283 
284 static int
285 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
286               struct pt_regs *regs)
287 {
288         struct sigframe __user *frame;
289         void __user *restorer;
290         int err = 0;
291         void __user *fpstate = NULL;
292 
293         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
294 
295         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
296                 return -EFAULT;
297 
298         if (__put_user(sig, &frame->sig))
299                 return -EFAULT;
300 
301         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
302                 return -EFAULT;
303 
304         if (_NSIG_WORDS > 1) {
305                 if (__copy_to_user(&frame->extramask, &set->sig[1],
306                                    sizeof(frame->extramask)))
307                         return -EFAULT;
308         }
309 
310         if (current->mm->context.vdso)
311                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
312         else
313                 restorer = &frame->retcode;
314         if (ka->sa.sa_flags & SA_RESTORER)
315                 restorer = ka->sa.sa_restorer;
316 
317         /* Set up to return from userspace.  */
318         err |= __put_user(restorer, &frame->pretcode);
319 
320         /*
321          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
322          *
323          * WE DO NOT USE IT ANY MORE! It's only left here for historical
324          * reasons and because gdb uses it as a signature to notice
325          * signal handler stack frames.
326          */
327         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
328 
329         if (err)
330                 return -EFAULT;
331 
332         /* Set up registers for signal handler */
333         regs->sp = (unsigned long)frame;
334         regs->ip = (unsigned long)ka->sa.sa_handler;
335         regs->ax = (unsigned long)sig;
336         regs->dx = 0;
337         regs->cx = 0;
338 
339         regs->ds = __USER_DS;
340         regs->es = __USER_DS;
341         regs->ss = __USER_DS;
342         regs->cs = __USER_CS;
343 
344         return 0;
345 }
346 
347 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
348                             sigset_t *set, struct pt_regs *regs)
349 {
350         struct rt_sigframe __user *frame;
351         void __user *restorer;
352         int err = 0;
353         void __user *fpstate = NULL;
354 
355         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
356 
357         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
358                 return -EFAULT;
359 
360         put_user_try {
361                 put_user_ex(sig, &frame->sig);
362                 put_user_ex(&frame->info, &frame->pinfo);
363                 put_user_ex(&frame->uc, &frame->puc);
364                 err |= copy_siginfo_to_user(&frame->info, info);
365 
366                 /* Create the ucontext.  */
367                 if (cpu_has_xsave)
368                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
369                 else
370                         put_user_ex(0, &frame->uc.uc_flags);
371                 put_user_ex(0, &frame->uc.uc_link);
372                 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
373                 put_user_ex(sas_ss_flags(regs->sp),
374                             &frame->uc.uc_stack.ss_flags);
375                 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
376                 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
377                                         regs, set->sig[0]);
378                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
379 
380                 /* Set up to return from userspace.  */
381                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
382                 if (ka->sa.sa_flags & SA_RESTORER)
383                         restorer = ka->sa.sa_restorer;
384                 put_user_ex(restorer, &frame->pretcode);
385 
386                 /*
387                  * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
388                  *
389                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
390                  * reasons and because gdb uses it as a signature to notice
391                  * signal handler stack frames.
392                  */
393                 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
394         } put_user_catch(err);
395 
396         if (err)
397                 return -EFAULT;
398 
399         /* Set up registers for signal handler */
400         regs->sp = (unsigned long)frame;
401         regs->ip = (unsigned long)ka->sa.sa_handler;
402         regs->ax = (unsigned long)sig;
403         regs->dx = (unsigned long)&frame->info;
404         regs->cx = (unsigned long)&frame->uc;
405 
406         regs->ds = __USER_DS;
407         regs->es = __USER_DS;
408         regs->ss = __USER_DS;
409         regs->cs = __USER_CS;
410 
411         return 0;
412 }
413 #else /* !CONFIG_X86_32 */
414 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
415                             sigset_t *set, struct pt_regs *regs)
416 {
417         struct rt_sigframe __user *frame;
418         void __user *fp = NULL;
419         int err = 0;
420         struct task_struct *me = current;
421 
422         frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe), &fp);
423 
424         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
425                 return -EFAULT;
426 
427         if (ka->sa.sa_flags & SA_SIGINFO) {
428                 if (copy_siginfo_to_user(&frame->info, info))
429                         return -EFAULT;
430         }
431 
432         put_user_try {
433                 /* Create the ucontext.  */
434                 if (cpu_has_xsave)
435                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
436                 else
437                         put_user_ex(0, &frame->uc.uc_flags);
438                 put_user_ex(0, &frame->uc.uc_link);
439                 put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
440                 put_user_ex(sas_ss_flags(regs->sp),
441                             &frame->uc.uc_stack.ss_flags);
442                 put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
443                 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
444                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
445 
446                 /* Set up to return from userspace.  If provided, use a stub
447                    already in userspace.  */
448                 /* x86-64 should always use SA_RESTORER. */
449                 if (ka->sa.sa_flags & SA_RESTORER) {
450                         put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
451                 } else {
452                         /* could use a vstub here */
453                         err |= -EFAULT;
454                 }
455         } put_user_catch(err);
456 
457         if (err)
458                 return -EFAULT;
459 
460         /* Set up registers for signal handler */
461         regs->di = sig;
462         /* In case the signal handler was declared without prototypes */
463         regs->ax = 0;
464 
465         /* This also works for non SA_SIGINFO handlers because they expect the
466            next argument after the signal number on the stack. */
467         regs->si = (unsigned long)&frame->info;
468         regs->dx = (unsigned long)&frame->uc;
469         regs->ip = (unsigned long) ka->sa.sa_handler;
470 
471         regs->sp = (unsigned long)frame;
472 
473         /* Set up the CS register to run signal handlers in 64-bit mode,
474            even if the handler happens to be interrupting 32-bit code. */
475         regs->cs = __USER_CS;
476 
477         return 0;
478 }
479 #endif /* CONFIG_X86_32 */
480 
481 #ifdef CONFIG_X86_32
482 /*
483  * Atomically swap in the new signal mask, and wait for a signal.
484  */
485 asmlinkage int
486 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
487 {
488         mask &= _BLOCKABLE;
489         spin_lock_irq(&current->sighand->siglock);
490         current->saved_sigmask = current->blocked;
491         siginitset(&current->blocked, mask);
492         recalc_sigpending();
493         spin_unlock_irq(&current->sighand->siglock);
494 
495         current->state = TASK_INTERRUPTIBLE;
496         schedule();
497         set_restore_sigmask();
498 
499         return -ERESTARTNOHAND;
500 }
501 
502 asmlinkage int
503 sys_sigaction(int sig, const struct old_sigaction __user *act,
504               struct old_sigaction __user *oact)
505 {
506         struct k_sigaction new_ka, old_ka;
507         int ret = 0;
508 
509         if (act) {
510                 old_sigset_t mask;
511 
512                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
513                         return -EFAULT;
514 
515                 get_user_try {
516                         get_user_ex(new_ka.sa.sa_handler, &act->sa_handler);
517                         get_user_ex(new_ka.sa.sa_flags, &act->sa_flags);
518                         get_user_ex(mask, &act->sa_mask);
519                         get_user_ex(new_ka.sa.sa_restorer, &act->sa_restorer);
520                 } get_user_catch(ret);
521 
522                 if (ret)
523                         return -EFAULT;
524                 siginitset(&new_ka.sa.sa_mask, mask);
525         }
526 
527         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
528 
529         if (!ret && oact) {
530                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
531                         return -EFAULT;
532 
533                 put_user_try {
534                         put_user_ex(old_ka.sa.sa_handler, &oact->sa_handler);
535                         put_user_ex(old_ka.sa.sa_flags, &oact->sa_flags);
536                         put_user_ex(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
537                         put_user_ex(old_ka.sa.sa_restorer, &oact->sa_restorer);
538                 } put_user_catch(ret);
539 
540                 if (ret)
541                         return -EFAULT;
542         }
543 
544         return ret;
545 }
546 #endif /* CONFIG_X86_32 */
547 
548 long
549 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
550                 struct pt_regs *regs)
551 {
552         return do_sigaltstack(uss, uoss, regs->sp);
553 }
554 
555 /*
556  * Do a signal return; undo the signal stack.
557  */
558 #ifdef CONFIG_X86_32
559 unsigned long sys_sigreturn(struct pt_regs *regs)
560 {
561         struct sigframe __user *frame;
562         unsigned long ax;
563         sigset_t set;
564 
565         frame = (struct sigframe __user *)(regs->sp - 8);
566 
567         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
568                 goto badframe;
569         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
570                 && __copy_from_user(&set.sig[1], &frame->extramask,
571                                     sizeof(frame->extramask))))
572                 goto badframe;
573 
574         sigdelsetmask(&set, ~_BLOCKABLE);
575         spin_lock_irq(&current->sighand->siglock);
576         current->blocked = set;
577         recalc_sigpending();
578         spin_unlock_irq(&current->sighand->siglock);
579 
580         if (restore_sigcontext(regs, &frame->sc, &ax))
581                 goto badframe;
582         return ax;
583 
584 badframe:
585         signal_fault(regs, frame, "sigreturn");
586 
587         return 0;
588 }
589 #endif /* CONFIG_X86_32 */
590 
591 long sys_rt_sigreturn(struct pt_regs *regs)
592 {
593         struct rt_sigframe __user *frame;
594         unsigned long ax;
595         sigset_t set;
596 
597         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
598         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
599                 goto badframe;
600         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
601                 goto badframe;
602 
603         sigdelsetmask(&set, ~_BLOCKABLE);
604         spin_lock_irq(&current->sighand->siglock);
605         current->blocked = set;
606         recalc_sigpending();
607         spin_unlock_irq(&current->sighand->siglock);
608 
609         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
610                 goto badframe;
611 
612         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
613                 goto badframe;
614 
615         return ax;
616 
617 badframe:
618         signal_fault(regs, frame, "rt_sigreturn");
619         return 0;
620 }
621 
622 /*
623  * OK, we're invoking a handler:
624  */
625 static int signr_convert(int sig)
626 {
627 #ifdef CONFIG_X86_32
628         struct thread_info *info = current_thread_info();
629 
630         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
631                 return info->exec_domain->signal_invmap[sig];
632 #endif /* CONFIG_X86_32 */
633         return sig;
634 }
635 
636 #ifdef CONFIG_X86_32
637 
638 #define is_ia32 1
639 #define ia32_setup_frame        __setup_frame
640 #define ia32_setup_rt_frame     __setup_rt_frame
641 
642 #else /* !CONFIG_X86_32 */
643 
644 #ifdef CONFIG_IA32_EMULATION
645 #define is_ia32 test_thread_flag(TIF_IA32)
646 #else /* !CONFIG_IA32_EMULATION */
647 #define is_ia32 0
648 #endif /* CONFIG_IA32_EMULATION */
649 
650 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
651                 sigset_t *set, struct pt_regs *regs);
652 int ia32_setup_frame(int sig, struct k_sigaction *ka,
653                 sigset_t *set, struct pt_regs *regs);
654 
655 #endif /* CONFIG_X86_32 */
656 
657 static int
658 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
659                sigset_t *set, struct pt_regs *regs)
660 {
661         int usig = signr_convert(sig);
662         int ret;
663 
664         /* Set up the stack frame */
665         if (is_ia32) {
666                 if (ka->sa.sa_flags & SA_SIGINFO)
667                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
668                 else
669                         ret = ia32_setup_frame(usig, ka, set, regs);
670         } else
671                 ret = __setup_rt_frame(sig, ka, info, set, regs);
672 
673         if (ret) {
674                 force_sigsegv(sig, current);
675                 return -EFAULT;
676         }
677 
678         return ret;
679 }
680 
681 static int
682 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
683               sigset_t *oldset, struct pt_regs *regs)
684 {
685         int ret;
686 
687         /* Are we from a system call? */
688         if (syscall_get_nr(current, regs) >= 0) {
689                 /* If so, check system call restarting.. */
690                 switch (syscall_get_error(current, regs)) {
691                 case -ERESTART_RESTARTBLOCK:
692                 case -ERESTARTNOHAND:
693                         regs->ax = -EINTR;
694                         break;
695 
696                 case -ERESTARTSYS:
697                         if (!(ka->sa.sa_flags & SA_RESTART)) {
698                                 regs->ax = -EINTR;
699                                 break;
700                         }
701                 /* fallthrough */
702                 case -ERESTARTNOINTR:
703                         regs->ax = regs->orig_ax;
704                         regs->ip -= 2;
705                         break;
706                 }
707         }
708 
709         /*
710          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
711          * flag so that register information in the sigcontext is correct.
712          */
713         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
714             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
715                 regs->flags &= ~X86_EFLAGS_TF;
716 
717         ret = setup_rt_frame(sig, ka, info, oldset, regs);
718 
719         if (ret)
720                 return ret;
721 
722 #ifdef CONFIG_X86_64
723         /*
724          * This has nothing to do with segment registers,
725          * despite the name.  This magic affects uaccess.h
726          * macros' behavior.  Reset it to the normal setting.
727          */
728         set_fs(USER_DS);
729 #endif
730 
731         /*
732          * Clear the direction flag as per the ABI for function entry.
733          */
734         regs->flags &= ~X86_EFLAGS_DF;
735 
736         /*
737          * Clear TF when entering the signal handler, but
738          * notify any tracer that was single-stepping it.
739          * The tracer may want to single-step inside the
740          * handler too.
741          */
742         regs->flags &= ~X86_EFLAGS_TF;
743 
744         spin_lock_irq(&current->sighand->siglock);
745         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
746         if (!(ka->sa.sa_flags & SA_NODEFER))
747                 sigaddset(&current->blocked, sig);
748         recalc_sigpending();
749         spin_unlock_irq(&current->sighand->siglock);
750 
751         tracehook_signal_handler(sig, info, ka, regs,
752                                  test_thread_flag(TIF_SINGLESTEP));
753 
754         return 0;
755 }
756 
757 #ifdef CONFIG_X86_32
758 #define NR_restart_syscall      __NR_restart_syscall
759 #else /* !CONFIG_X86_32 */
760 #define NR_restart_syscall      \
761         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
762 #endif /* CONFIG_X86_32 */
763 
764 /*
765  * Note that 'init' is a special process: it doesn't get signals it doesn't
766  * want to handle. Thus you cannot kill init even with a SIGKILL even by
767  * mistake.
768  */
769 static void do_signal(struct pt_regs *regs)
770 {
771         struct k_sigaction ka;
772         siginfo_t info;
773         int signr;
774         sigset_t *oldset;
775 
776         /*
777          * We want the common case to go fast, which is why we may in certain
778          * cases get here from kernel mode. Just return without doing anything
779          * if so.
780          * X86_32: vm86 regs switched out by assembly code before reaching
781          * here, so testing against kernel CS suffices.
782          */
783         if (!user_mode(regs))
784                 return;
785 
786         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
787                 oldset = &current->saved_sigmask;
788         else
789                 oldset = &current->blocked;
790 
791         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
792         if (signr > 0) {
793                 /* Whee! Actually deliver the signal.  */
794                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
795                         /*
796                          * A signal was successfully delivered; the saved
797                          * sigmask will have been stored in the signal frame,
798                          * and will be restored by sigreturn, so we can simply
799                          * clear the TS_RESTORE_SIGMASK flag.
800                          */
801                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
802                 }
803                 return;
804         }
805 
806         /* Did we come from a system call? */
807         if (syscall_get_nr(current, regs) >= 0) {
808                 /* Restart the system call - no handlers present */
809                 switch (syscall_get_error(current, regs)) {
810                 case -ERESTARTNOHAND:
811                 case -ERESTARTSYS:
812                 case -ERESTARTNOINTR:
813                         regs->ax = regs->orig_ax;
814                         regs->ip -= 2;
815                         break;
816 
817                 case -ERESTART_RESTARTBLOCK:
818                         regs->ax = NR_restart_syscall;
819                         regs->ip -= 2;
820                         break;
821                 }
822         }
823 
824         /*
825          * If there's no signal to deliver, we just put the saved sigmask
826          * back.
827          */
828         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
829                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
830                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
831         }
832 }
833 
834 /*
835  * notification of userspace execution resumption
836  * - triggered by the TIF_WORK_MASK flags
837  */
838 void
839 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
840 {
841 #ifdef CONFIG_X86_MCE
842         /* notify userspace of pending MCEs */
843         if (thread_info_flags & _TIF_MCE_NOTIFY)
844                 mce_notify_process();
845 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
846 
847         /* deal with pending signal delivery */
848         if (thread_info_flags & _TIF_SIGPENDING)
849                 do_signal(regs);
850 
851         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
852                 clear_thread_flag(TIF_NOTIFY_RESUME);
853                 tracehook_notify_resume(regs);
854                 if (current->replacement_session_keyring)
855                         key_replace_session_keyring();
856         }
857         if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
858                 fire_user_return_notifiers();
859 
860 #ifdef CONFIG_X86_32
861         clear_thread_flag(TIF_IRET);
862 #endif /* CONFIG_X86_32 */
863 }
864 
865 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
866 {
867         struct task_struct *me = current;
868 
869         if (show_unhandled_signals && printk_ratelimit()) {
870                 printk("%s"
871                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
872                        task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
873                        me->comm, me->pid, where, frame,
874                        regs->ip, regs->sp, regs->orig_ax);
875                 print_vma_addr(" in ", regs->ip);
876                 printk(KERN_CONT "\n");
877         }
878 
879         force_sig(SIGSEGV, me);
880 }
881 

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