arch/sh/kernel/signal_32.c

   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 | _TIF_NOTIFY_SIGNAL))
 503                 do_signal(regs, save_r0);
 504
 505         if (thread_info_flags & _TIF_NOTIFY_RESUME)
 506                 tracehook_notify_resume(regs);
 507 }