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Linux/arch/sh/kernel/signal_32.c

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  1 /*
  2  *  linux/arch/sh/kernel/signal.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  *
  6  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  7  *
  8  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
  9  *
 10  */
 11 #include <linux/sched.h>
 12 #include <linux/mm.h>
 13 #include <linux/smp.h>
 14 #include <linux/kernel.h>
 15 #include <linux/signal.h>
 16 #include <linux/errno.h>
 17 #include <linux/wait.h>
 18 #include <linux/ptrace.h>
 19 #include <linux/unistd.h>
 20 #include <linux/stddef.h>
 21 #include <linux/tty.h>
 22 #include <linux/elf.h>
 23 #include <linux/personality.h>
 24 #include <linux/binfmts.h>
 25 #include <linux/io.h>
 26 #include <linux/tracehook.h>
 27 #include <asm/ucontext.h>
 28 #include <asm/uaccess.h>
 29 #include <asm/pgtable.h>
 30 #include <asm/cacheflush.h>
 31 #include <asm/syscalls.h>
 32 #include <asm/fpu.h>
 33 
 34 struct fdpic_func_descriptor {
 35         unsigned long   text;
 36         unsigned long   GOT;
 37 };
 38 
 39 /*
 40  * The following define adds a 64 byte gap between the signal
 41  * stack frame and previous contents of the stack.  This allows
 42  * frame unwinding in a function epilogue but only if a frame
 43  * pointer is used in the function.  This is necessary because
 44  * current gcc compilers (<4.3) do not generate unwind info on
 45  * SH for function epilogues.
 46  */
 47 #define UNWINDGUARD 64
 48 
 49 /*
 50  * Do a signal return; undo the signal stack.
 51  */
 52 
 53 #define MOVW(n)  (0x9300|((n)-2))       /* Move mem word at PC+n to R3 */
 54 #if defined(CONFIG_CPU_SH2)
 55 #define TRAP_NOARG 0xc320               /* Syscall w/no args (NR in R3) */
 56 #else
 57 #define TRAP_NOARG 0xc310               /* Syscall w/no args (NR in R3) */
 58 #endif
 59 #define OR_R0_R0 0x200b                 /* or r0,r0 (insert to avoid hardware bug) */
 60 
 61 struct sigframe
 62 {
 63         struct sigcontext sc;
 64         unsigned long extramask[_NSIG_WORDS-1];
 65         u16 retcode[8];
 66 };
 67 
 68 struct rt_sigframe
 69 {
 70         struct siginfo info;
 71         struct ucontext uc;
 72         u16 retcode[8];
 73 };
 74 
 75 #ifdef CONFIG_SH_FPU
 76 static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
 77 {
 78         struct task_struct *tsk = current;
 79 
 80         if (!(boot_cpu_data.flags & CPU_HAS_FPU))
 81                 return 0;
 82 
 83         set_used_math();
 84         return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
 85                                 sizeof(long)*(16*2+2));
 86 }
 87 
 88 static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
 89                                       struct pt_regs *regs)
 90 {
 91         struct task_struct *tsk = current;
 92 
 93         if (!(boot_cpu_data.flags & CPU_HAS_FPU))
 94                 return 0;
 95 
 96         if (!used_math())
 97                 return __put_user(0, &sc->sc_ownedfp);
 98 
 99         if (__put_user(1, &sc->sc_ownedfp))
100                 return -EFAULT;
101 
102         /* This will cause a "finit" to be triggered by the next
103            attempted FPU operation by the 'current' process.
104            */
105         clear_used_math();
106 
107         unlazy_fpu(tsk, regs);
108         return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
109                               sizeof(long)*(16*2+2));
110 }
111 #endif /* CONFIG_SH_FPU */
112 
113 static int
114 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
115 {
116         unsigned int err = 0;
117 
118 #define COPY(x)         err |= __get_user(regs->x, &sc->sc_##x)
119                         COPY(regs[1]);
120         COPY(regs[2]);  COPY(regs[3]);
121         COPY(regs[4]);  COPY(regs[5]);
122         COPY(regs[6]);  COPY(regs[7]);
123         COPY(regs[8]);  COPY(regs[9]);
124         COPY(regs[10]); COPY(regs[11]);
125         COPY(regs[12]); COPY(regs[13]);
126         COPY(regs[14]); COPY(regs[15]);
127         COPY(gbr);      COPY(mach);
128         COPY(macl);     COPY(pr);
129         COPY(sr);       COPY(pc);
130 #undef COPY
131 
132 #ifdef CONFIG_SH_FPU
133         if (boot_cpu_data.flags & CPU_HAS_FPU) {
134                 int owned_fp;
135                 struct task_struct *tsk = current;
136 
137                 regs->sr |= SR_FD; /* Release FPU */
138                 clear_fpu(tsk, regs);
139                 clear_used_math();
140                 err |= __get_user (owned_fp, &sc->sc_ownedfp);
141                 if (owned_fp)
142                         err |= restore_sigcontext_fpu(sc);
143         }
144 #endif
145 
146         regs->tra = -1;         /* disable syscall checks */
147         err |= __get_user(*r0_p, &sc->sc_regs[0]);
148         return err;
149 }
150 
151 asmlinkage int sys_sigreturn(unsigned long r4, unsigned long r5,
152                              unsigned long r6, unsigned long r7,
153                              struct pt_regs __regs)
154 {
155         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
156         struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
157         sigset_t set;
158         int r0;
159 
160         /* Always make any pending restarted system calls return -EINTR */
161         current_thread_info()->restart_block.fn = do_no_restart_syscall;
162 
163         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
164                 goto badframe;
165 
166         if (__get_user(set.sig[0], &frame->sc.oldmask)
167             || (_NSIG_WORDS > 1
168                 && __copy_from_user(&set.sig[1], &frame->extramask,
169                                     sizeof(frame->extramask))))
170                 goto badframe;
171 
172         set_current_blocked(&set);
173 
174         if (restore_sigcontext(regs, &frame->sc, &r0))
175                 goto badframe;
176         return r0;
177 
178 badframe:
179         force_sig(SIGSEGV, current);
180         return 0;
181 }
182 
183 asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
184                                 unsigned long r6, unsigned long r7,
185                                 struct pt_regs __regs)
186 {
187         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
188         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
189         sigset_t set;
190         int r0;
191 
192         /* Always make any pending restarted system calls return -EINTR */
193         current_thread_info()->restart_block.fn = do_no_restart_syscall;
194 
195         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
196                 goto badframe;
197 
198         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
199                 goto badframe;
200 
201         set_current_blocked(&set);
202 
203         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
204                 goto badframe;
205 
206         if (restore_altstack(&frame->uc.uc_stack))
207                 goto badframe;
208 
209         return r0;
210 
211 badframe:
212         force_sig(SIGSEGV, current);
213         return 0;
214 }
215 
216 /*
217  * Set up a signal frame.
218  */
219 
220 static int
221 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
222                  unsigned long mask)
223 {
224         int err = 0;
225 
226 #define COPY(x)         err |= __put_user(regs->x, &sc->sc_##x)
227         COPY(regs[0]);  COPY(regs[1]);
228         COPY(regs[2]);  COPY(regs[3]);
229         COPY(regs[4]);  COPY(regs[5]);
230         COPY(regs[6]);  COPY(regs[7]);
231         COPY(regs[8]);  COPY(regs[9]);
232         COPY(regs[10]); COPY(regs[11]);
233         COPY(regs[12]); COPY(regs[13]);
234         COPY(regs[14]); COPY(regs[15]);
235         COPY(gbr);      COPY(mach);
236         COPY(macl);     COPY(pr);
237         COPY(sr);       COPY(pc);
238 #undef COPY
239 
240 #ifdef CONFIG_SH_FPU
241         err |= save_sigcontext_fpu(sc, regs);
242 #endif
243 
244         /* non-iBCS2 extensions.. */
245         err |= __put_user(mask, &sc->oldmask);
246 
247         return err;
248 }
249 
250 /*
251  * Determine which stack to use..
252  */
253 static inline void __user *
254 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
255 {
256         if (ka->sa.sa_flags & SA_ONSTACK) {
257                 if (sas_ss_flags(sp) == 0)
258                         sp = current->sas_ss_sp + current->sas_ss_size;
259         }
260 
261         return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
262 }
263 
264 /* These symbols are defined with the addresses in the vsyscall page.
265    See vsyscall-trapa.S.  */
266 extern void __kernel_sigreturn(void);
267 extern void __kernel_rt_sigreturn(void);
268 
269 static int setup_frame(int sig, struct k_sigaction *ka,
270                         sigset_t *set, struct pt_regs *regs)
271 {
272         struct sigframe __user *frame;
273         int err = 0;
274         int signal;
275 
276         frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
277 
278         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
279                 goto give_sigsegv;
280 
281         signal = current_thread_info()->exec_domain
282                 && current_thread_info()->exec_domain->signal_invmap
283                 && sig < 32
284                 ? current_thread_info()->exec_domain->signal_invmap[sig]
285                 : sig;
286 
287         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
288 
289         if (_NSIG_WORDS > 1)
290                 err |= __copy_to_user(frame->extramask, &set->sig[1],
291                                       sizeof(frame->extramask));
292 
293         /* Set up to return from userspace.  If provided, use a stub
294            already in userspace.  */
295         if (ka->sa.sa_flags & SA_RESTORER) {
296                 regs->pr = (unsigned long) ka->sa.sa_restorer;
297 #ifdef CONFIG_VSYSCALL
298         } else if (likely(current->mm->context.vdso)) {
299                 regs->pr = VDSO_SYM(&__kernel_sigreturn);
300 #endif
301         } else {
302                 /* Generate return code (system call to sigreturn) */
303                 err |= __put_user(MOVW(7), &frame->retcode[0]);
304                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
305                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
306                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
307                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
308                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
309                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
310                 err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
311                 regs->pr = (unsigned long) frame->retcode;
312                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
313         }
314 
315         if (err)
316                 goto give_sigsegv;
317 
318         /* Set up registers for signal handler */
319         regs->regs[15] = (unsigned long) frame;
320         regs->regs[4] = signal; /* Arg for signal handler */
321         regs->regs[5] = 0;
322         regs->regs[6] = (unsigned long) &frame->sc;
323 
324         if (current->personality & FDPIC_FUNCPTRS) {
325                 struct fdpic_func_descriptor __user *funcptr =
326                         (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
327 
328                 err |= __get_user(regs->pc, &funcptr->text);
329                 err |= __get_user(regs->regs[12], &funcptr->GOT);
330         } else
331                 regs->pc = (unsigned long)ka->sa.sa_handler;
332 
333         if (err)
334                 goto give_sigsegv;
335 
336         set_fs(USER_DS);
337 
338         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
339                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
340 
341         return 0;
342 
343 give_sigsegv:
344         force_sigsegv(sig, current);
345         return -EFAULT;
346 }
347 
348 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
349                            sigset_t *set, struct pt_regs *regs)
350 {
351         struct rt_sigframe __user *frame;
352         int err = 0;
353         int signal;
354 
355         frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
356 
357         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
358                 goto give_sigsegv;
359 
360         signal = current_thread_info()->exec_domain
361                 && current_thread_info()->exec_domain->signal_invmap
362                 && sig < 32
363                 ? current_thread_info()->exec_domain->signal_invmap[sig]
364                 : sig;
365 
366         err |= copy_siginfo_to_user(&frame->info, info);
367 
368         /* Create the ucontext.  */
369         err |= __put_user(0, &frame->uc.uc_flags);
370         err |= __put_user(NULL, &frame->uc.uc_link);
371         err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
372         err |= setup_sigcontext(&frame->uc.uc_mcontext,
373                                 regs, set->sig[0]);
374         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
375 
376         /* Set up to return from userspace.  If provided, use a stub
377            already in userspace.  */
378         if (ka->sa.sa_flags & SA_RESTORER) {
379                 regs->pr = (unsigned long) ka->sa.sa_restorer;
380 #ifdef CONFIG_VSYSCALL
381         } else if (likely(current->mm->context.vdso)) {
382                 regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
383 #endif
384         } else {
385                 /* Generate return code (system call to rt_sigreturn) */
386                 err |= __put_user(MOVW(7), &frame->retcode[0]);
387                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
388                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
389                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
390                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
391                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
392                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
393                 err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
394                 regs->pr = (unsigned long) frame->retcode;
395                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
396         }
397 
398         if (err)
399                 goto give_sigsegv;
400 
401         /* Set up registers for signal handler */
402         regs->regs[15] = (unsigned long) frame;
403         regs->regs[4] = signal; /* Arg for signal handler */
404         regs->regs[5] = (unsigned long) &frame->info;
405         regs->regs[6] = (unsigned long) &frame->uc;
406 
407         if (current->personality & FDPIC_FUNCPTRS) {
408                 struct fdpic_func_descriptor __user *funcptr =
409                         (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
410 
411                 err |= __get_user(regs->pc, &funcptr->text);
412                 err |= __get_user(regs->regs[12], &funcptr->GOT);
413         } else
414                 regs->pc = (unsigned long)ka->sa.sa_handler;
415 
416         if (err)
417                 goto give_sigsegv;
418 
419         set_fs(USER_DS);
420 
421         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
422                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
423 
424         return 0;
425 
426 give_sigsegv:
427         force_sigsegv(sig, current);
428         return -EFAULT;
429 }
430 
431 static inline void
432 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
433                        struct sigaction *sa)
434 {
435         /* If we're not from a syscall, bail out */
436         if (regs->tra < 0)
437                 return;
438 
439         /* check for system call restart.. */
440         switch (regs->regs[0]) {
441                 case -ERESTART_RESTARTBLOCK:
442                 case -ERESTARTNOHAND:
443                 no_system_call_restart:
444                         regs->regs[0] = -EINTR;
445                         break;
446 
447                 case -ERESTARTSYS:
448                         if (!(sa->sa_flags & SA_RESTART))
449                                 goto no_system_call_restart;
450                 /* fallthrough */
451                 case -ERESTARTNOINTR:
452                         regs->regs[0] = save_r0;
453                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
454                         break;
455         }
456 }
457 
458 /*
459  * OK, we're invoking a handler
460  */
461 static void
462 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
463               struct pt_regs *regs, unsigned int save_r0)
464 {
465         sigset_t *oldset = sigmask_to_save();
466         int ret;
467 
468         /* Set up the stack frame */
469         if (ka->sa.sa_flags & SA_SIGINFO)
470                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
471         else
472                 ret = setup_frame(sig, ka, oldset, regs);
473 
474         if (ret)
475                 return;
476         signal_delivered(sig, info, ka, regs,
477                         test_thread_flag(TIF_SINGLESTEP));
478 }
479 
480 /*
481  * Note that 'init' is a special process: it doesn't get signals it doesn't
482  * want to handle. Thus you cannot kill init even with a SIGKILL even by
483  * mistake.
484  *
485  * Note that we go through the signals twice: once to check the signals that
486  * the kernel can handle, and then we build all the user-level signal handling
487  * stack-frames in one go after that.
488  */
489 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
490 {
491         siginfo_t info;
492         int signr;
493         struct k_sigaction ka;
494 
495         /*
496          * We want the common case to go fast, which
497          * is why we may in certain cases get here from
498          * kernel mode. Just return without doing anything
499          * if so.
500          */
501         if (!user_mode(regs))
502                 return;
503 
504         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
505         if (signr > 0) {
506                 handle_syscall_restart(save_r0, regs, &ka.sa);
507 
508                 /* Whee!  Actually deliver the signal.  */
509                 handle_signal(signr, &ka, &info, regs, save_r0);
510                 return;
511         }
512 
513         /* Did we come from a system call? */
514         if (regs->tra >= 0) {
515                 /* Restart the system call - no handlers present */
516                 if (regs->regs[0] == -ERESTARTNOHAND ||
517                     regs->regs[0] == -ERESTARTSYS ||
518                     regs->regs[0] == -ERESTARTNOINTR) {
519                         regs->regs[0] = save_r0;
520                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
521                 } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
522                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
523                         regs->regs[3] = __NR_restart_syscall;
524                 }
525         }
526 
527         /*
528          * If there's no signal to deliver, we just put the saved sigmask
529          * back.
530          */
531         restore_saved_sigmask();
532 }
533 
534 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
535                                  unsigned long thread_info_flags)
536 {
537         /* deal with pending signal delivery */
538         if (thread_info_flags & _TIF_SIGPENDING)
539                 do_signal(regs, save_r0);
540 
541         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
542                 clear_thread_flag(TIF_NOTIFY_RESUME);
543                 tracehook_notify_resume(regs);
544         }
545 }
546 

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