arch/sh/kernel/signal_32.c

   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(void)
 152 {
 153         struct pt_regs *regs = current_pt_regs();
 154         struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
 155         sigset_t set;
 156         int r0;
 157
 158         /* Always make any pending restarted system calls return -EINTR */
 159         current->restart_block.fn = do_no_restart_syscall;
 160
 161         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 162                 goto badframe;
 163
 164         if (__get_user(set.sig[0], &frame->sc.oldmask)
 165             || (_NSIG_WORDS > 1
 166                 && __copy_from_user(&set.sig[1], &frame->extramask,
 167                                     sizeof(frame->extramask))))
 168                 goto badframe;
 169
 170         set_current_blocked(&set);
 171
 172         if (restore_sigcontext(regs, &frame->sc, &r0))
 173                 goto badframe;
 174         return r0;
 175
 176 badframe:
 177         force_sig(SIGSEGV, current);
 178         return 0;
 179 }
 180
 181 asmlinkage int sys_rt_sigreturn(void)
 182 {
 183         struct pt_regs *regs = current_pt_regs();
 184         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
 185         sigset_t set;
 186         int r0;
 187
 188         /* Always make any pending restarted system calls return -EINTR */
 189         current->restart_block.fn = do_no_restart_syscall;
 190
 191         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 192                 goto badframe;
 193
 194         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 195                 goto badframe;
 196
 197         set_current_blocked(&set);
 198
 199         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 200                 goto badframe;
 201
 202         if (restore_altstack(&frame->uc.uc_stack))
 203                 goto badframe;
 204
 205         return r0;
 206
 207 badframe:
 208         force_sig(SIGSEGV, current);
 209         return 0;
 210 }
 211
 212 /*
 213  * Set up a signal frame.
 214  */
 215
 216 static int
 217 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 218                  unsigned long mask)
 219 {
 220         int err = 0;
 221
 222 #define COPY(x)         err |= __put_user(regs->x, &sc->sc_##x)
 223         COPY(regs[0]);  COPY(regs[1]);
 224         COPY(regs[2]);  COPY(regs[3]);
 225         COPY(regs[4]);  COPY(regs[5]);
 226         COPY(regs[6]);  COPY(regs[7]);
 227         COPY(regs[8]);  COPY(regs[9]);
 228         COPY(regs[10]); COPY(regs[11]);
 229         COPY(regs[12]); COPY(regs[13]);
 230         COPY(regs[14]); COPY(regs[15]);
 231         COPY(gbr);      COPY(mach);
 232         COPY(macl);     COPY(pr);
 233         COPY(sr);       COPY(pc);
 234 #undef COPY
 235
 236 #ifdef CONFIG_SH_FPU
 237         err |= save_sigcontext_fpu(sc, regs);
 238 #endif
 239
 240         /* non-iBCS2 extensions.. */
 241         err |= __put_user(mask, &sc->oldmask);
 242
 243         return err;
 244 }
 245
 246 /*
 247  * Determine which stack to use..
 248  */
 249 static inline void __user *
 250 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 251 {
 252         if (ka->sa.sa_flags & SA_ONSTACK) {
 253                 if (sas_ss_flags(sp) == 0)
 254                         sp = current->sas_ss_sp + current->sas_ss_size;
 255         }
 256
 257         return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
 258 }
 259
 260 /* These symbols are defined with the addresses in the vsyscall page.
 261    See vsyscall-trapa.S.  */
 262 extern void __kernel_sigreturn(void);
 263 extern void __kernel_rt_sigreturn(void);
 264
 265 static int setup_frame(struct ksignal *ksig, sigset_t *set,
 266                        struct pt_regs *regs)
 267 {
 268         struct sigframe __user *frame;
 269         int err = 0, sig = ksig->sig;
 270
 271         frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
 272
 273         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 274                 return -EFAULT;
 275
 276         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
 277
 278         if (_NSIG_WORDS > 1)
 279                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 280                                       sizeof(frame->extramask));
 281
 282         /* Set up to return from userspace.  If provided, use a stub
 283            already in userspace.  */
 284         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 285                 regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
 286 #ifdef CONFIG_VSYSCALL
 287         } else if (likely(current->mm->context.vdso)) {
 288                 regs->pr = VDSO_SYM(&__kernel_sigreturn);
 289 #endif
 290         } else {
 291                 /* Generate return code (system call to sigreturn) */
 292                 err |= __put_user(MOVW(7), &frame->retcode[0]);
 293                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
 294                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
 295                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
 296                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
 297                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
 298                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
 299                 err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
 300                 regs->pr = (unsigned long) frame->retcode;
 301                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
 302         }
 303
 304         if (err)
 305                 return -EFAULT;
 306
 307         /* Set up registers for signal handler */
 308         regs->regs[15] = (unsigned long) frame;
 309         regs->regs[4] = sig; /* Arg for signal handler */
 310         regs->regs[5] = 0;
 311         regs->regs[6] = (unsigned long) &frame->sc;
 312
 313         if (current->personality & FDPIC_FUNCPTRS) {
 314                 struct fdpic_func_descriptor __user *funcptr =
 315                         (struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
 316
 317                 err |= __get_user(regs->pc, &funcptr->text);
 318                 err |= __get_user(regs->regs[12], &funcptr->GOT);
 319         } else
 320                 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
 321
 322         if (err)
 323                 return -EFAULT;
 324
 325         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
 326                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
 327
 328         return 0;
 329 }
 330
 331 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 332                           struct pt_regs *regs)
 333 {
 334         struct rt_sigframe __user *frame;
 335         int err = 0, sig = ksig->sig;
 336
 337         frame = get_sigframe(&ksig->ka, regs->regs[15], sizeof(*frame));
 338
 339         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 340                 return -EFAULT;
 341
 342         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 343
 344         /* Create the ucontext.  */
 345         err |= __put_user(0, &frame->uc.uc_flags);
 346         err |= __put_user(NULL, &frame->uc.uc_link);
 347         err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
 348         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 349                                 regs, set->sig[0]);
 350         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 351
 352         /* Set up to return from userspace.  If provided, use a stub
 353            already in userspace.  */
 354         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 355                 regs->pr = (unsigned long) ksig->ka.sa.sa_restorer;
 356 #ifdef CONFIG_VSYSCALL
 357         } else if (likely(current->mm->context.vdso)) {
 358                 regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
 359 #endif
 360         } else {
 361                 /* Generate return code (system call to rt_sigreturn) */
 362                 err |= __put_user(MOVW(7), &frame->retcode[0]);
 363                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
 364                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
 365                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
 366                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
 367                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
 368                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
 369                 err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
 370                 regs->pr = (unsigned long) frame->retcode;
 371                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
 372         }
 373
 374         if (err)
 375                 return -EFAULT;
 376
 377         /* Set up registers for signal handler */
 378         regs->regs[15] = (unsigned long) frame;
 379         regs->regs[4] = sig; /* Arg for signal handler */
 380         regs->regs[5] = (unsigned long) &frame->info;
 381         regs->regs[6] = (unsigned long) &frame->uc;
 382
 383         if (current->personality & FDPIC_FUNCPTRS) {
 384                 struct fdpic_func_descriptor __user *funcptr =
 385                         (struct fdpic_func_descriptor __user *)ksig->ka.sa.sa_handler;
 386
 387                 err |= __get_user(regs->pc, &funcptr->text);
 388                 err |= __get_user(regs->regs[12], &funcptr->GOT);
 389         } else
 390                 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
 391
 392         if (err)
 393                 return -EFAULT;
 394
 395         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
 396                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
 397
 398         return 0;
 399 }
 400
 401 static inline void
 402 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
 403                        struct sigaction *sa)
 404 {
 405         /* If we're not from a syscall, bail out */
 406         if (regs->tra < 0)
 407                 return;
 408
 409         /* check for system call restart.. */
 410         switch (regs->regs[0]) {
 411                 case -ERESTART_RESTARTBLOCK:
 412                 case -ERESTARTNOHAND:
 413                 no_system_call_restart:
 414                         regs->regs[0] = -EINTR;
 415                         break;
 416
 417                 case -ERESTARTSYS:
 418                         if (!(sa->sa_flags & SA_RESTART))
 419                                 goto no_system_call_restart;
 420                 /* fallthrough */
 421                 case -ERESTARTNOINTR:
 422                         regs->regs[0] = save_r0;
 423                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 424                         break;
 425         }
 426 }
 427
 428 /*
 429  * OK, we're invoking a handler
 430  */
 431 static void
 432 handle_signal(struct ksignal *ksig, struct pt_regs *regs, unsigned int save_r0)
 433 {
 434         sigset_t *oldset = sigmask_to_save();
 435         int ret;
 436
 437         /* Set up the stack frame */
 438         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 439                 ret = setup_rt_frame(ksig, oldset, regs);
 440         else
 441                 ret = setup_frame(ksig, oldset, regs);
 442
 443         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 444 }
 445
 446 /*
 447  * Note that 'init' is a special process: it doesn't get signals it doesn't
 448  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 449  * mistake.
 450  *
 451  * Note that we go through the signals twice: once to check the signals that
 452  * the kernel can handle, and then we build all the user-level signal handling
 453  * stack-frames in one go after that.
 454  */
 455 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 456 {
 457         struct ksignal ksig;
 458
 459         /*
 460          * We want the common case to go fast, which
 461          * is why we may in certain cases get here from
 462          * kernel mode. Just return without doing anything
 463          * if so.
 464          */
 465         if (!user_mode(regs))
 466                 return;
 467
 468         if (get_signal(&ksig)) {
 469                 handle_syscall_restart(save_r0, regs, &ksig.ka.sa);
 470
 471                 /* Whee!  Actually deliver the signal.  */
 472                 handle_signal(&ksig, regs, save_r0);
 473                 return;
 474         }
 475
 476         /* Did we come from a system call? */
 477         if (regs->tra >= 0) {
 478                 /* Restart the system call - no handlers present */
 479                 if (regs->regs[0] == -ERESTARTNOHAND ||
 480                     regs->regs[0] == -ERESTARTSYS ||
 481                     regs->regs[0] == -ERESTARTNOINTR) {
 482                         regs->regs[0] = save_r0;
 483                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 484                 } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
 485                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 486                         regs->regs[3] = __NR_restart_syscall;
 487                 }
 488         }
 489
 490         /*
 491          * If there's no signal to deliver, we just put the saved sigmask
 492          * back.
 493          */
 494         restore_saved_sigmask();
 495 }
 496
 497 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
 498                                  unsigned long thread_info_flags)
 499 {
 500         /* deal with pending signal delivery */
 501         if (thread_info_flags & _TIF_SIGPENDING)
 502                 do_signal(regs, save_r0);
 503
 504         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 505                 clear_thread_flag(TIF_NOTIFY_RESUME);
 506                 tracehook_notify_resume(regs);
 507         }
 508 }