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TOMOYO Linux Cross Reference
Linux/arch/x86/kernel/signal.c

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  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 
 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 11 
 12 #include <linux/sched.h>
 13 #include <linux/mm.h>
 14 #include <linux/smp.h>
 15 #include <linux/kernel.h>
 16 #include <linux/errno.h>
 17 #include <linux/wait.h>
 18 #include <linux/tracehook.h>
 19 #include <linux/unistd.h>
 20 #include <linux/stddef.h>
 21 #include <linux/personality.h>
 22 #include <linux/uaccess.h>
 23 #include <linux/user-return-notifier.h>
 24 #include <linux/uprobes.h>
 25 #include <linux/context_tracking.h>
 26 
 27 #include <asm/processor.h>
 28 #include <asm/ucontext.h>
 29 #include <asm/fpu/internal.h>
 30 #include <asm/fpu/signal.h>
 31 #include <asm/vdso.h>
 32 #include <asm/mce.h>
 33 #include <asm/sighandling.h>
 34 #include <asm/vm86.h>
 35 
 36 #ifdef CONFIG_X86_64
 37 #include <asm/proto.h>
 38 #include <asm/ia32_unistd.h>
 39 #endif /* CONFIG_X86_64 */
 40 
 41 #include <asm/syscall.h>
 42 #include <asm/syscalls.h>
 43 
 44 #include <asm/sigframe.h>
 45 
 46 #define COPY(x)                 do {                    \
 47         get_user_ex(regs->x, &sc->x);                   \
 48 } while (0)
 49 
 50 #define GET_SEG(seg)            ({                      \
 51         unsigned short tmp;                             \
 52         get_user_ex(tmp, &sc->seg);                     \
 53         tmp;                                            \
 54 })
 55 
 56 #define COPY_SEG(seg)           do {                    \
 57         regs->seg = GET_SEG(seg);                       \
 58 } while (0)
 59 
 60 #define COPY_SEG_CPL3(seg)      do {                    \
 61         regs->seg = GET_SEG(seg) | 3;                   \
 62 } while (0)
 63 
 64 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 65 {
 66         unsigned long buf_val;
 67         void __user *buf;
 68         unsigned int tmpflags;
 69         unsigned int err = 0;
 70 
 71         /* Always make any pending restarted system calls return -EINTR */
 72         current->restart_block.fn = do_no_restart_syscall;
 73 
 74         get_user_try {
 75 
 76 #ifdef CONFIG_X86_32
 77                 set_user_gs(regs, GET_SEG(gs));
 78                 COPY_SEG(fs);
 79                 COPY_SEG(es);
 80                 COPY_SEG(ds);
 81 #endif /* CONFIG_X86_32 */
 82 
 83                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 84                 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
 85 
 86 #ifdef CONFIG_X86_64
 87                 COPY(r8);
 88                 COPY(r9);
 89                 COPY(r10);
 90                 COPY(r11);
 91                 COPY(r12);
 92                 COPY(r13);
 93                 COPY(r14);
 94                 COPY(r15);
 95 #endif /* CONFIG_X86_64 */
 96 
 97 #ifdef CONFIG_X86_32
 98                 COPY_SEG_CPL3(cs);
 99                 COPY_SEG_CPL3(ss);
100 #else /* !CONFIG_X86_32 */
101                 /* Kernel saves and restores only the CS segment register on signals,
102                  * which is the bare minimum needed to allow mixed 32/64-bit code.
103                  * App's signal handler can save/restore other segments if needed. */
104                 COPY_SEG_CPL3(cs);
105 #endif /* CONFIG_X86_32 */
106 
107                 get_user_ex(tmpflags, &sc->flags);
108                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
109                 regs->orig_ax = -1;             /* disable syscall checks */
110 
111                 get_user_ex(buf_val, &sc->fpstate);
112                 buf = (void __user *)buf_val;
113         } get_user_catch(err);
114 
115         err |= fpu__restore_sig(buf, config_enabled(CONFIG_X86_32));
116 
117         force_iret();
118 
119         return err;
120 }
121 
122 int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
123                      struct pt_regs *regs, unsigned long mask)
124 {
125         int err = 0;
126 
127         put_user_try {
128 
129 #ifdef CONFIG_X86_32
130                 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
131                 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
132                 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
133                 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
134 #endif /* CONFIG_X86_32 */
135 
136                 put_user_ex(regs->di, &sc->di);
137                 put_user_ex(regs->si, &sc->si);
138                 put_user_ex(regs->bp, &sc->bp);
139                 put_user_ex(regs->sp, &sc->sp);
140                 put_user_ex(regs->bx, &sc->bx);
141                 put_user_ex(regs->dx, &sc->dx);
142                 put_user_ex(regs->cx, &sc->cx);
143                 put_user_ex(regs->ax, &sc->ax);
144 #ifdef CONFIG_X86_64
145                 put_user_ex(regs->r8, &sc->r8);
146                 put_user_ex(regs->r9, &sc->r9);
147                 put_user_ex(regs->r10, &sc->r10);
148                 put_user_ex(regs->r11, &sc->r11);
149                 put_user_ex(regs->r12, &sc->r12);
150                 put_user_ex(regs->r13, &sc->r13);
151                 put_user_ex(regs->r14, &sc->r14);
152                 put_user_ex(regs->r15, &sc->r15);
153 #endif /* CONFIG_X86_64 */
154 
155                 put_user_ex(current->thread.trap_nr, &sc->trapno);
156                 put_user_ex(current->thread.error_code, &sc->err);
157                 put_user_ex(regs->ip, &sc->ip);
158 #ifdef CONFIG_X86_32
159                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
160                 put_user_ex(regs->flags, &sc->flags);
161                 put_user_ex(regs->sp, &sc->sp_at_signal);
162                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
163 #else /* !CONFIG_X86_32 */
164                 put_user_ex(regs->flags, &sc->flags);
165                 put_user_ex(regs->cs, &sc->cs);
166                 put_user_ex(0, &sc->gs);
167                 put_user_ex(0, &sc->fs);
168 #endif /* CONFIG_X86_32 */
169 
170                 put_user_ex(fpstate, &sc->fpstate);
171 
172                 /* non-iBCS2 extensions.. */
173                 put_user_ex(mask, &sc->oldmask);
174                 put_user_ex(current->thread.cr2, &sc->cr2);
175         } put_user_catch(err);
176 
177         return err;
178 }
179 
180 /*
181  * Set up a signal frame.
182  */
183 
184 /*
185  * Determine which stack to use..
186  */
187 static unsigned long align_sigframe(unsigned long sp)
188 {
189 #ifdef CONFIG_X86_32
190         /*
191          * Align the stack pointer according to the i386 ABI,
192          * i.e. so that on function entry ((sp + 4) & 15) == 0.
193          */
194         sp = ((sp + 4) & -16ul) - 4;
195 #else /* !CONFIG_X86_32 */
196         sp = round_down(sp, 16) - 8;
197 #endif
198         return sp;
199 }
200 
201 static void __user *
202 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
203              void __user **fpstate)
204 {
205         /* Default to using normal stack */
206         unsigned long math_size = 0;
207         unsigned long sp = regs->sp;
208         unsigned long buf_fx = 0;
209         int onsigstack = on_sig_stack(sp);
210         struct fpu *fpu = &current->thread.fpu;
211 
212         /* redzone */
213         if (config_enabled(CONFIG_X86_64))
214                 sp -= 128;
215 
216         if (!onsigstack) {
217                 /* This is the X/Open sanctioned signal stack switching.  */
218                 if (ka->sa.sa_flags & SA_ONSTACK) {
219                         if (current->sas_ss_size)
220                                 sp = current->sas_ss_sp + current->sas_ss_size;
221                 } else if (config_enabled(CONFIG_X86_32) &&
222                            (regs->ss & 0xffff) != __USER_DS &&
223                            !(ka->sa.sa_flags & SA_RESTORER) &&
224                            ka->sa.sa_restorer) {
225                                 /* This is the legacy signal stack switching. */
226                                 sp = (unsigned long) ka->sa.sa_restorer;
227                 }
228         }
229 
230         if (fpu->fpstate_active) {
231                 sp = fpu__alloc_mathframe(sp, config_enabled(CONFIG_X86_32),
232                                           &buf_fx, &math_size);
233                 *fpstate = (void __user *)sp;
234         }
235 
236         sp = align_sigframe(sp - frame_size);
237 
238         /*
239          * If we are on the alternate signal stack and would overflow it, don't.
240          * Return an always-bogus address instead so we will die with SIGSEGV.
241          */
242         if (onsigstack && !likely(on_sig_stack(sp)))
243                 return (void __user *)-1L;
244 
245         /* save i387 and extended state */
246         if (fpu->fpstate_active &&
247             copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
248                 return (void __user *)-1L;
249 
250         return (void __user *)sp;
251 }
252 
253 #ifdef CONFIG_X86_32
254 static const struct {
255         u16 poplmovl;
256         u32 val;
257         u16 int80;
258 } __attribute__((packed)) retcode = {
259         0xb858,         /* popl %eax; movl $..., %eax */
260         __NR_sigreturn,
261         0x80cd,         /* int $0x80 */
262 };
263 
264 static const struct {
265         u8  movl;
266         u32 val;
267         u16 int80;
268         u8  pad;
269 } __attribute__((packed)) rt_retcode = {
270         0xb8,           /* movl $..., %eax */
271         __NR_rt_sigreturn,
272         0x80cd,         /* int $0x80 */
273         0
274 };
275 
276 static int
277 __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
278               struct pt_regs *regs)
279 {
280         struct sigframe __user *frame;
281         void __user *restorer;
282         int err = 0;
283         void __user *fpstate = NULL;
284 
285         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
286 
287         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
288                 return -EFAULT;
289 
290         if (__put_user(sig, &frame->sig))
291                 return -EFAULT;
292 
293         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
294                 return -EFAULT;
295 
296         if (_NSIG_WORDS > 1) {
297                 if (__copy_to_user(&frame->extramask, &set->sig[1],
298                                    sizeof(frame->extramask)))
299                         return -EFAULT;
300         }
301 
302         if (current->mm->context.vdso)
303                 restorer = current->mm->context.vdso +
304                         vdso_image_32.sym___kernel_sigreturn;
305         else
306                 restorer = &frame->retcode;
307         if (ksig->ka.sa.sa_flags & SA_RESTORER)
308                 restorer = ksig->ka.sa.sa_restorer;
309 
310         /* Set up to return from userspace.  */
311         err |= __put_user(restorer, &frame->pretcode);
312 
313         /*
314          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
315          *
316          * WE DO NOT USE IT ANY MORE! It's only left here for historical
317          * reasons and because gdb uses it as a signature to notice
318          * signal handler stack frames.
319          */
320         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
321 
322         if (err)
323                 return -EFAULT;
324 
325         /* Set up registers for signal handler */
326         regs->sp = (unsigned long)frame;
327         regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
328         regs->ax = (unsigned long)sig;
329         regs->dx = 0;
330         regs->cx = 0;
331 
332         regs->ds = __USER_DS;
333         regs->es = __USER_DS;
334         regs->ss = __USER_DS;
335         regs->cs = __USER_CS;
336 
337         return 0;
338 }
339 
340 static int __setup_rt_frame(int sig, struct ksignal *ksig,
341                             sigset_t *set, struct pt_regs *regs)
342 {
343         struct rt_sigframe __user *frame;
344         void __user *restorer;
345         int err = 0;
346         void __user *fpstate = NULL;
347 
348         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
349 
350         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
351                 return -EFAULT;
352 
353         put_user_try {
354                 put_user_ex(sig, &frame->sig);
355                 put_user_ex(&frame->info, &frame->pinfo);
356                 put_user_ex(&frame->uc, &frame->puc);
357 
358                 /* Create the ucontext.  */
359                 if (cpu_has_xsave)
360                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
361                 else
362                         put_user_ex(0, &frame->uc.uc_flags);
363                 put_user_ex(0, &frame->uc.uc_link);
364                 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
365 
366                 /* Set up to return from userspace.  */
367                 restorer = current->mm->context.vdso +
368                         vdso_image_32.sym___kernel_rt_sigreturn;
369                 if (ksig->ka.sa.sa_flags & SA_RESTORER)
370                         restorer = ksig->ka.sa.sa_restorer;
371                 put_user_ex(restorer, &frame->pretcode);
372 
373                 /*
374                  * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
375                  *
376                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
377                  * reasons and because gdb uses it as a signature to notice
378                  * signal handler stack frames.
379                  */
380                 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
381         } put_user_catch(err);
382         
383         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
384         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
385                                 regs, set->sig[0]);
386         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
387 
388         if (err)
389                 return -EFAULT;
390 
391         /* Set up registers for signal handler */
392         regs->sp = (unsigned long)frame;
393         regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
394         regs->ax = (unsigned long)sig;
395         regs->dx = (unsigned long)&frame->info;
396         regs->cx = (unsigned long)&frame->uc;
397 
398         regs->ds = __USER_DS;
399         regs->es = __USER_DS;
400         regs->ss = __USER_DS;
401         regs->cs = __USER_CS;
402 
403         return 0;
404 }
405 #else /* !CONFIG_X86_32 */
406 static int __setup_rt_frame(int sig, struct ksignal *ksig,
407                             sigset_t *set, struct pt_regs *regs)
408 {
409         struct rt_sigframe __user *frame;
410         void __user *fp = NULL;
411         int err = 0;
412 
413         frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
414 
415         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
416                 return -EFAULT;
417 
418         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
419                 if (copy_siginfo_to_user(&frame->info, &ksig->info))
420                         return -EFAULT;
421         }
422 
423         put_user_try {
424                 /* Create the ucontext.  */
425                 if (cpu_has_xsave)
426                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
427                 else
428                         put_user_ex(0, &frame->uc.uc_flags);
429                 put_user_ex(0, &frame->uc.uc_link);
430                 save_altstack_ex(&frame->uc.uc_stack, regs->sp);
431 
432                 /* Set up to return from userspace.  If provided, use a stub
433                    already in userspace.  */
434                 /* x86-64 should always use SA_RESTORER. */
435                 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
436                         put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
437                 } else {
438                         /* could use a vstub here */
439                         err |= -EFAULT;
440                 }
441         } put_user_catch(err);
442 
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         if (err)
447                 return -EFAULT;
448 
449         /* Set up registers for signal handler */
450         regs->di = sig;
451         /* In case the signal handler was declared without prototypes */
452         regs->ax = 0;
453 
454         /* This also works for non SA_SIGINFO handlers because they expect the
455            next argument after the signal number on the stack. */
456         regs->si = (unsigned long)&frame->info;
457         regs->dx = (unsigned long)&frame->uc;
458         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
459 
460         regs->sp = (unsigned long)frame;
461 
462         /* Set up the CS register to run signal handlers in 64-bit mode,
463            even if the handler happens to be interrupting 32-bit code. */
464         regs->cs = __USER_CS;
465 
466         return 0;
467 }
468 #endif /* CONFIG_X86_32 */
469 
470 static int x32_setup_rt_frame(struct ksignal *ksig,
471                               compat_sigset_t *set,
472                               struct pt_regs *regs)
473 {
474 #ifdef CONFIG_X86_X32_ABI
475         struct rt_sigframe_x32 __user *frame;
476         void __user *restorer;
477         int err = 0;
478         void __user *fpstate = NULL;
479 
480         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
481 
482         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
483                 return -EFAULT;
484 
485         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
486                 if (copy_siginfo_to_user32(&frame->info, &ksig->info))
487                         return -EFAULT;
488         }
489 
490         put_user_try {
491                 /* Create the ucontext.  */
492                 if (cpu_has_xsave)
493                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
494                 else
495                         put_user_ex(0, &frame->uc.uc_flags);
496                 put_user_ex(0, &frame->uc.uc_link);
497                 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
498                 put_user_ex(0, &frame->uc.uc__pad0);
499 
500                 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
501                         restorer = ksig->ka.sa.sa_restorer;
502                 } else {
503                         /* could use a vstub here */
504                         restorer = NULL;
505                         err |= -EFAULT;
506                 }
507                 put_user_ex(restorer, &frame->pretcode);
508         } put_user_catch(err);
509 
510         err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
511                                 regs, set->sig[0]);
512         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
513 
514         if (err)
515                 return -EFAULT;
516 
517         /* Set up registers for signal handler */
518         regs->sp = (unsigned long) frame;
519         regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
520 
521         /* We use the x32 calling convention here... */
522         regs->di = ksig->sig;
523         regs->si = (unsigned long) &frame->info;
524         regs->dx = (unsigned long) &frame->uc;
525 
526         loadsegment(ds, __USER_DS);
527         loadsegment(es, __USER_DS);
528 
529         regs->cs = __USER_CS;
530         regs->ss = __USER_DS;
531 #endif  /* CONFIG_X86_X32_ABI */
532 
533         return 0;
534 }
535 
536 /*
537  * Do a signal return; undo the signal stack.
538  */
539 #ifdef CONFIG_X86_32
540 asmlinkage unsigned long sys_sigreturn(void)
541 {
542         struct pt_regs *regs = current_pt_regs();
543         struct sigframe __user *frame;
544         sigset_t set;
545 
546         frame = (struct sigframe __user *)(regs->sp - 8);
547 
548         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
549                 goto badframe;
550         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
551                 && __copy_from_user(&set.sig[1], &frame->extramask,
552                                     sizeof(frame->extramask))))
553                 goto badframe;
554 
555         set_current_blocked(&set);
556 
557         if (restore_sigcontext(regs, &frame->sc))
558                 goto badframe;
559         return regs->ax;
560 
561 badframe:
562         signal_fault(regs, frame, "sigreturn");
563 
564         return 0;
565 }
566 #endif /* CONFIG_X86_32 */
567 
568 asmlinkage long sys_rt_sigreturn(void)
569 {
570         struct pt_regs *regs = current_pt_regs();
571         struct rt_sigframe __user *frame;
572         sigset_t set;
573 
574         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
575         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
576                 goto badframe;
577         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
578                 goto badframe;
579 
580         set_current_blocked(&set);
581 
582         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
583                 goto badframe;
584 
585         if (restore_altstack(&frame->uc.uc_stack))
586                 goto badframe;
587 
588         return regs->ax;
589 
590 badframe:
591         signal_fault(regs, frame, "rt_sigreturn");
592         return 0;
593 }
594 
595 static inline int is_ia32_compat_frame(void)
596 {
597         return config_enabled(CONFIG_IA32_EMULATION) &&
598                test_thread_flag(TIF_IA32);
599 }
600 
601 static inline int is_ia32_frame(void)
602 {
603         return config_enabled(CONFIG_X86_32) || is_ia32_compat_frame();
604 }
605 
606 static inline int is_x32_frame(void)
607 {
608         return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32);
609 }
610 
611 static int
612 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
613 {
614         int usig = ksig->sig;
615         sigset_t *set = sigmask_to_save();
616         compat_sigset_t *cset = (compat_sigset_t *) set;
617 
618         /* Set up the stack frame */
619         if (is_ia32_frame()) {
620                 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
621                         return ia32_setup_rt_frame(usig, ksig, cset, regs);
622                 else
623                         return ia32_setup_frame(usig, ksig, cset, regs);
624         } else if (is_x32_frame()) {
625                 return x32_setup_rt_frame(ksig, cset, regs);
626         } else {
627                 return __setup_rt_frame(ksig->sig, ksig, set, regs);
628         }
629 }
630 
631 static void
632 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
633 {
634         bool stepping, failed;
635         struct fpu *fpu = &current->thread.fpu;
636 
637         if (v8086_mode(regs))
638                 save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
639 
640         /* Are we from a system call? */
641         if (syscall_get_nr(current, regs) >= 0) {
642                 /* If so, check system call restarting.. */
643                 switch (syscall_get_error(current, regs)) {
644                 case -ERESTART_RESTARTBLOCK:
645                 case -ERESTARTNOHAND:
646                         regs->ax = -EINTR;
647                         break;
648 
649                 case -ERESTARTSYS:
650                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
651                                 regs->ax = -EINTR;
652                                 break;
653                         }
654                 /* fallthrough */
655                 case -ERESTARTNOINTR:
656                         regs->ax = regs->orig_ax;
657                         regs->ip -= 2;
658                         break;
659                 }
660         }
661 
662         /*
663          * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
664          * so that register information in the sigcontext is correct and
665          * then notify the tracer before entering the signal handler.
666          */
667         stepping = test_thread_flag(TIF_SINGLESTEP);
668         if (stepping)
669                 user_disable_single_step(current);
670 
671         failed = (setup_rt_frame(ksig, regs) < 0);
672         if (!failed) {
673                 /*
674                  * Clear the direction flag as per the ABI for function entry.
675                  *
676                  * Clear RF when entering the signal handler, because
677                  * it might disable possible debug exception from the
678                  * signal handler.
679                  *
680                  * Clear TF for the case when it wasn't set by debugger to
681                  * avoid the recursive send_sigtrap() in SIGTRAP handler.
682                  */
683                 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
684                 /*
685                  * Ensure the signal handler starts with the new fpu state.
686                  */
687                 if (fpu->fpstate_active)
688                         fpu__clear(fpu);
689         }
690         signal_setup_done(failed, ksig, stepping);
691 }
692 
693 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
694 {
695 #if defined(CONFIG_X86_32) || !defined(CONFIG_X86_64)
696         return __NR_restart_syscall;
697 #else /* !CONFIG_X86_32 && CONFIG_X86_64 */
698         return test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall :
699                 __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
700 #endif /* CONFIG_X86_32 || !CONFIG_X86_64 */
701 }
702 
703 /*
704  * Note that 'init' is a special process: it doesn't get signals it doesn't
705  * want to handle. Thus you cannot kill init even with a SIGKILL even by
706  * mistake.
707  */
708 void do_signal(struct pt_regs *regs)
709 {
710         struct ksignal ksig;
711 
712         if (get_signal(&ksig)) {
713                 /* Whee! Actually deliver the signal.  */
714                 handle_signal(&ksig, regs);
715                 return;
716         }
717 
718         /* Did we come from a system call? */
719         if (syscall_get_nr(current, regs) >= 0) {
720                 /* Restart the system call - no handlers present */
721                 switch (syscall_get_error(current, regs)) {
722                 case -ERESTARTNOHAND:
723                 case -ERESTARTSYS:
724                 case -ERESTARTNOINTR:
725                         regs->ax = regs->orig_ax;
726                         regs->ip -= 2;
727                         break;
728 
729                 case -ERESTART_RESTARTBLOCK:
730                         regs->ax = get_nr_restart_syscall(regs);
731                         regs->ip -= 2;
732                         break;
733                 }
734         }
735 
736         /*
737          * If there's no signal to deliver, we just put the saved sigmask
738          * back.
739          */
740         restore_saved_sigmask();
741 }
742 
743 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
744 {
745         struct task_struct *me = current;
746 
747         if (show_unhandled_signals && printk_ratelimit()) {
748                 printk("%s"
749                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
750                        task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
751                        me->comm, me->pid, where, frame,
752                        regs->ip, regs->sp, regs->orig_ax);
753                 print_vma_addr(" in ", regs->ip);
754                 pr_cont("\n");
755         }
756 
757         force_sig(SIGSEGV, me);
758 }
759 
760 #ifdef CONFIG_X86_X32_ABI
761 asmlinkage long sys32_x32_rt_sigreturn(void)
762 {
763         struct pt_regs *regs = current_pt_regs();
764         struct rt_sigframe_x32 __user *frame;
765         sigset_t set;
766 
767         frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
768 
769         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
770                 goto badframe;
771         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
772                 goto badframe;
773 
774         set_current_blocked(&set);
775 
776         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
777                 goto badframe;
778 
779         if (compat_restore_altstack(&frame->uc.uc_stack))
780                 goto badframe;
781 
782         return regs->ax;
783 
784 badframe:
785         signal_fault(regs, frame, "x32 rt_sigreturn");
786         return 0;
787 }
788 #endif
789 

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