LXR linux/arch/sh/kernel/signal

   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
  34struct 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
  61struct sigframe
  62{
  63        struct sigcontext sc;
  64        unsigned long extramask[_NSIG_WORDS-1];
  65        u16 retcode[8];
  66};
  67
  68struct rt_sigframe
  69{
  70        struct siginfo info;
  71        struct ucontext uc;
  72        u16 retcode[8];
  73};
  74
  75#ifdef CONFIG_SH_FPU
  76static 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
  88static 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
 113static int
 114restore_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
 151asmlinkage 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
 176badframe:
 177        force_sig(SIGSEGV, current);
 178        return 0;
 179}
 180
 181asmlinkage 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
 207badframe:
 208        force_sig(SIGSEGV, current);
 209        return 0;
 210}
 211
 212/*
 213 * Set up a signal frame.
 214 */
 215
 216static int
 217setup_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 */
 249static inline void __user *
 250get_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.  */
 262extern void __kernel_sigreturn(void);
 263extern void __kernel_rt_sigreturn(void);
 264
 265static 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
 331static 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
 401static inline void
 402handle_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 */
 431static void
 432handle_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 */
 455static 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
 497asmlinkage 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}
 509