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Linux/arch/sh/kernel/signal_32.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/arch/sh/kernel/signal.c
  4  *
  5  *  Copyright (C) 1991, 1992  Linus Torvalds
  6  *
  7  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  8  *
  9  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 10  *
 11  */
 12 #include <linux/sched.h>
 13 #include <linux/sched/task_stack.h>
 14 #include <linux/mm.h>
 15 #include <linux/smp.h>
 16 #include <linux/kernel.h>
 17 #include <linux/signal.h>
 18 #include <linux/errno.h>
 19 #include <linux/wait.h>
 20 #include <linux/ptrace.h>
 21 #include <linux/unistd.h>
 22 #include <linux/stddef.h>
 23 #include <linux/tty.h>
 24 #include <linux/elf.h>
 25 #include <linux/personality.h>
 26 #include <linux/binfmts.h>
 27 #include <linux/io.h>
 28 #include <linux/tracehook.h>
 29 #include <asm/ucontext.h>
 30 #include <linux/uaccess.h>
 31 #include <asm/cacheflush.h>
 32 #include <asm/syscalls.h>
 33 #include <asm/fpu.h>
 34 
 35 struct fdpic_func_descriptor {
 36         unsigned long   text;
 37         unsigned long   GOT;
 38 };
 39 
 40 /*
 41  * The following define adds a 64 byte gap between the signal
 42  * stack frame and previous contents of the stack.  This allows
 43  * frame unwinding in a function epilogue but only if a frame
 44  * pointer is used in the function.  This is necessary because
 45  * current gcc compilers (<4.3) do not generate unwind info on
 46  * SH for function epilogues.
 47  */
 48 #define UNWINDGUARD 64
 49 
 50 /*
 51  * Do a signal return; undo the signal stack.
 52  */
 53 
 54 #define MOVW(n)  (0x9300|((n)-2))       /* Move mem word at PC+n to R3 */
 55 #if defined(CONFIG_CPU_SH2)
 56 #define TRAP_NOARG 0xc320               /* Syscall w/no args (NR in R3) */
 57 #else
 58 #define TRAP_NOARG 0xc310               /* Syscall w/no args (NR in R3) */
 59 #endif
 60 #define OR_R0_R0 0x200b                 /* or r0,r0 (insert to avoid hardware bug) */
 61 
 62 struct sigframe
 63 {
 64         struct sigcontext sc;
 65         unsigned long extramask[_NSIG_WORDS-1];
 66         u16 retcode[8];
 67 };
 68 
 69 struct rt_sigframe
 70 {
 71         struct siginfo info;
 72         struct ucontext uc;
 73         u16 retcode[8];
 74 };
 75 
 76 #ifdef CONFIG_SH_FPU
 77 static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
 78 {
 79         struct task_struct *tsk = current;
 80 
 81         if (!(boot_cpu_data.flags & CPU_HAS_FPU))
 82                 return 0;
 83 
 84         set_used_math();
 85         return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
 86                                 sizeof(long)*(16*2+2));
 87 }
 88 
 89 static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
 90                                       struct pt_regs *regs)
 91 {
 92         struct task_struct *tsk = current;
 93 
 94         if (!(boot_cpu_data.flags & CPU_HAS_FPU))
 95                 return 0;
 96 
 97         if (!used_math())
 98                 return __put_user(0, &sc->sc_ownedfp);
 99 
100         if (__put_user(1, &sc->sc_ownedfp))
101                 return -EFAULT;
102 
103         /* This will cause a "finit" to be triggered by the next
104            attempted FPU operation by the 'current' process.
105            */
106         clear_used_math();
107 
108         unlazy_fpu(tsk, regs);
109         return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
110                               sizeof(long)*(16*2+2));
111 }
112 #endif /* CONFIG_SH_FPU */
113 
114 static int
115 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
116 {
117         unsigned int err = 0;
118 
119 #define COPY(x)         err |= __get_user(regs->x, &sc->sc_##x)
120                         COPY(regs[1]);
121         COPY(regs[2]);  COPY(regs[3]);
122         COPY(regs[4]);  COPY(regs[5]);
123         COPY(regs[6]);  COPY(regs[7]);
124         COPY(regs[8]);  COPY(regs[9]);
125         COPY(regs[10]); COPY(regs[11]);
126         COPY(regs[12]); COPY(regs[13]);
127         COPY(regs[14]); COPY(regs[15]);
128         COPY(gbr);      COPY(mach);
129         COPY(macl);     COPY(pr);
130         COPY(sr);       COPY(pc);
131 #undef COPY
132 
133 #ifdef CONFIG_SH_FPU
134         if (boot_cpu_data.flags & CPU_HAS_FPU) {
135                 int owned_fp;
136                 struct task_struct *tsk = current;
137 
138                 regs->sr |= SR_FD; /* Release FPU */
139                 clear_fpu(tsk, regs);
140                 clear_used_math();
141                 err |= __get_user (owned_fp, &sc->sc_ownedfp);
142                 if (owned_fp)
143                         err |= restore_sigcontext_fpu(sc);
144         }
145 #endif
146 
147         regs->tra = -1;         /* disable syscall checks */
148         err |= __get_user(*r0_p, &sc->sc_regs[0]);
149         return err;
150 }
151 
152 asmlinkage int sys_sigreturn(void)
153 {
154         struct pt_regs *regs = current_pt_regs();
155         struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
156         sigset_t set;
157         int r0;
158 
159         /* Always make any pending restarted system calls return -EINTR */
160         current->restart_block.fn = do_no_restart_syscall;
161 
162         if (!access_ok(frame, sizeof(*frame)))
163                 goto badframe;
164 
165         if (__get_user(set.sig[0], &frame->sc.oldmask)
166             || (_NSIG_WORDS > 1
167                 && __copy_from_user(&set.sig[1], &frame->extramask,
168                                     sizeof(frame->extramask))))
169                 goto badframe;
170 
171         set_current_blocked(&set);
172 
173         if (restore_sigcontext(regs, &frame->sc, &r0))
174                 goto badframe;
175         return r0;
176 
177 badframe:
178         force_sig(SIGSEGV);
179         return 0;
180 }
181 
182 asmlinkage int sys_rt_sigreturn(void)
183 {
184         struct pt_regs *regs = current_pt_regs();
185         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
186         sigset_t set;
187         int r0;
188 
189         /* Always make any pending restarted system calls return -EINTR */
190         current->restart_block.fn = do_no_restart_syscall;
191 
192         if (!access_ok(frame, sizeof(*frame)))
193                 goto badframe;
194 
195         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
196                 goto badframe;
197 
198         set_current_blocked(&set);
199 
200         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
201                 goto badframe;
202 
203         if (restore_altstack(&frame->uc.uc_stack))
204                 goto badframe;
205 
206         return r0;
207 
208 badframe:
209         force_sig(SIGSEGV);
210         return 0;
211 }
212 
213 /*
214  * Set up a signal frame.
215  */
216 
217 static int
218 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
219                  unsigned long mask)
220 {
221         int err = 0;
222 
223 #define COPY(x)         err |= __put_user(regs->x, &sc->sc_##x)
224         COPY(regs[0]);  COPY(regs[1]);
225         COPY(regs[2]);  COPY(regs[3]);
226         COPY(regs[4]);  COPY(regs[5]);
227         COPY(regs[6]);  COPY(regs[7]);
228         COPY(regs[8]);  COPY(regs[9]);
229         COPY(regs[10]); COPY(regs[11]);
230         COPY(regs[12]); COPY(regs[13]);
231         COPY(regs[14]); COPY(regs[15]);
232         COPY(gbr);      COPY(mach);
233         COPY(macl);     COPY(pr);
234         COPY(sr);       COPY(pc);
235 #undef COPY
236 
237 #ifdef CONFIG_SH_FPU
238         err |= save_sigcontext_fpu(sc, regs);
239 #endif
240 
241         /* non-iBCS2 extensions.. */
242         err |= __put_user(mask, &sc->oldmask);
243 
244         return err;
245 }
246 
247 /*
248  * Determine which stack to use..
249  */
250 static inline void __user *
251 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
252 {
253         if (ka->sa.sa_flags & SA_ONSTACK) {
254                 if (sas_ss_flags(sp) == 0)
255                         sp = current->sas_ss_sp + current->sas_ss_size;
256         }
257 
258         return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
259 }
260 
261 /* These symbols are defined with the addresses in the vsyscall page.
262    See vsyscall-trapa.S.  */
263 extern void __kernel_sigreturn(void);
264 extern void __kernel_rt_sigreturn(void);
265 
266 static int setup_frame(struct ksignal *ksig, sigset_t *set,
267                        struct pt_regs *regs)
268 {
269         struct sigframe __user *frame;
270         int err = 0, sig = ksig->sig;
271 
272         frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
273 
274         if (!access_ok(frame, sizeof(*frame)))
275                 return -EFAULT;
276 
277         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
278 
279         if (_NSIG_WORDS > 1)
280                 err |= __copy_to_user(frame->extramask, &set->sig[1],
281                                       sizeof(frame->extramask));
282 
283         /* Set up to return from userspace.  If provided, use a stub
284            already in userspace.  */
285         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
286                 regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
287 #ifdef CONFIG_VSYSCALL
288         } else if (likely(current->mm->context.vdso)) {
289                 regs->pr = VDSO_SYM(&__kernel_sigreturn);
290 #endif
291         } else {
292                 /* Generate return code (system call to sigreturn) */
293                 err |= __put_user(MOVW(7), &frame->retcode[0]);
294                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
295                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
296                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
297                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
298                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
299                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
300                 err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
301                 regs->pr = (unsigned long) frame->retcode;
302                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
303         }
304 
305         if (err)
306                 return -EFAULT;
307 
308         /* Set up registers for signal handler */
309         regs->regs[15] = (unsigned long) frame;
310         regs->regs[4] = sig; /* Arg for signal handler */
311         regs->regs[5] = 0;
312         regs->regs[6] = (unsigned long) &frame->sc;
313 
314         if (current->personality & FDPIC_FUNCPTRS) {
315                 struct fdpic_func_descriptor __user *funcptr =
316                         (struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
317 
318                 err |= __get_user(regs->pc, &funcptr->text);
319                 err |= __get_user(regs->regs[12], &funcptr->GOT);
320         } else
321                 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
322 
323         if (err)
324                 return -EFAULT;
325 
326         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
327                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
328 
329         return 0;
330 }
331 
332 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
333                           struct pt_regs *regs)
334 {
335         struct rt_sigframe __user *frame;
336         int err = 0, sig = ksig->sig;
337 
338         frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
339 
340         if (!access_ok(frame, sizeof(*frame)))
341                 return -EFAULT;
342 
343         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
344 
345         /* Create the ucontext.  */
346         err |= __put_user(0, &frame->uc.uc_flags);
347         err |= __put_user(NULL, &frame->uc.uc_link);
348         err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
349         err |= setup_sigcontext(&frame->uc.uc_mcontext,
350                                 regs, set->sig[0]);
351         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
352 
353         /* Set up to return from userspace.  If provided, use a stub
354            already in userspace.  */
355         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
356                 regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
357 #ifdef CONFIG_VSYSCALL
358         } else if (likely(current->mm->context.vdso)) {
359                 regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
360 #endif
361         } else {
362                 /* Generate return code (system call to rt_sigreturn) */
363                 err |= __put_user(MOVW(7), &frame->retcode[0]);
364                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
365                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
366                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
367                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
368                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
369                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
370                 err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
371                 regs->pr = (unsigned long) frame->retcode;
372                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
373         }
374 
375         if (err)
376                 return -EFAULT;
377 
378         /* Set up registers for signal handler */
379         regs->regs[15] = (unsigned long) frame;
380         regs->regs[4] = sig; /* Arg for signal handler */
381         regs->regs[5] = (unsigned long) &frame->info;
382         regs->regs[6] = (unsigned long) &frame->uc;
383 
384         if (current->personality & FDPIC_FUNCPTRS) {
385                 struct fdpic_func_descriptor __user *funcptr =
386                         (struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
387 
388                 err |= __get_user(regs->pc, &funcptr->text);
389                 err |= __get_user(regs->regs[12], &funcptr->GOT);
390         } else
391                 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
392 
393         if (err)
394                 return -EFAULT;
395 
396         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
397                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
398 
399         return 0;
400 }
401 
402 static inline void
403 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
404                        struct sigaction *sa)
405 {
406         /* If we're not from a syscall, bail out */
407         if (regs->tra < 0)
408                 return;
409 
410         /* check for system call restart.. */
411         switch (regs->regs[0]) {
412                 case -ERESTART_RESTARTBLOCK:
413                 case -ERESTARTNOHAND:
414                 no_system_call_restart:
415                         regs->regs[0] = -EINTR;
416                         break;
417 
418                 case -ERESTARTSYS:
419                         if (!(sa->sa_flags & SA_RESTART))
420                                 goto no_system_call_restart;
421                 /* fallthrough */
422                 case -ERESTARTNOINTR:
423                         regs->regs[0] = save_r0;
424                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
425                         break;
426         }
427 }
428 
429 /*
430  * OK, we're invoking a handler
431  */
432 static void
433 handle_signal(struct ksignal *ksig, struct pt_regs *regs, unsigned int save_r0)
434 {
435         sigset_t *oldset = sigmask_to_save();
436         int ret;
437 
438         /* Set up the stack frame */
439         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
440                 ret = setup_rt_frame(ksig, oldset, regs);
441         else
442                 ret = setup_frame(ksig, oldset, regs);
443 
444         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
445 }
446 
447 /*
448  * Note that 'init' is a special process: it doesn't get signals it doesn't
449  * want to handle. Thus you cannot kill init even with a SIGKILL even by
450  * mistake.
451  *
452  * Note that we go through the signals twice: once to check the signals that
453  * the kernel can handle, and then we build all the user-level signal handling
454  * stack-frames in one go after that.
455  */
456 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
457 {
458         struct ksignal ksig;
459 
460         /*
461          * We want the common case to go fast, which
462          * is why we may in certain cases get here from
463          * kernel mode. Just return without doing anything
464          * if so.
465          */
466         if (!user_mode(regs))
467                 return;
468 
469         if (get_signal(&ksig)) {
470                 handle_syscall_restart(save_r0, regs, &ksig.ka.sa);
471 
472                 /* Whee!  Actually deliver the signal.  */
473                 handle_signal(&ksig, regs, save_r0);
474                 return;
475         }
476 
477         /* Did we come from a system call? */
478         if (regs->tra >= 0) {
479                 /* Restart the system call - no handlers present */
480                 if (regs->regs[0] == -ERESTARTNOHAND ||
481                     regs->regs[0] == -ERESTARTSYS ||
482                     regs->regs[0] == -ERESTARTNOINTR) {
483                         regs->regs[0] = save_r0;
484                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
485                 } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
486                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
487                         regs->regs[3] = __NR_restart_syscall;
488                 }
489         }
490 
491         /*
492          * If there's no signal to deliver, we just put the saved sigmask
493          * back.
494          */
495         restore_saved_sigmask();
496 }
497 
498 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
499                                  unsigned long thread_info_flags)
500 {
501         /* deal with pending signal delivery */
502         if (thread_info_flags & _TIF_SIGPENDING)
503                 do_signal(regs, save_r0);
504 
505         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
506                 clear_thread_flag(TIF_NOTIFY_RESUME);
507                 tracehook_notify_resume(regs);
508         }
509 }
510 

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