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