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(unsigned long r4, unsigned long r5,
 152                              unsigned long r6, unsigned long r7,
 153                              struct pt_regs __regs)
 154 {
 155         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 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_thread_info()->restart_block.fn = do_no_restart_syscall;
 162
 163         if (!access_ok(VERIFY_READ, 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, current);
 180         return 0;
 181 }
 182
 183 asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
 184                                 unsigned long r6, unsigned long r7,
 185                                 struct pt_regs __regs)
 186 {
 187         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 188         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
 189         sigset_t set;
 190         int r0;
 191
 192         /* Always make any pending restarted system calls return -EINTR */
 193         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 194
 195         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 196                 goto badframe;
 197
 198         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 199                 goto badframe;
 200
 201         set_current_blocked(&set);
 202
 203         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 204                 goto badframe;
 205
 206         if (restore_altstack(&frame->uc.uc_stack))
 207                 goto badframe;
 208
 209         return r0;
 210
 211 badframe:
 212         force_sig(SIGSEGV, current);
 213         return 0;
 214 }
 215
 216 /*
 217  * Set up a signal frame.
 218  */
 219
 220 static int
 221 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 222                  unsigned long mask)
 223 {
 224         int err = 0;
 225
 226 #define COPY(x)         err |= __put_user(regs->x, &sc->sc_##x)
 227         COPY(regs[0]);  COPY(regs[1]);
 228         COPY(regs[2]);  COPY(regs[3]);
 229         COPY(regs[4]);  COPY(regs[5]);
 230         COPY(regs[6]);  COPY(regs[7]);
 231         COPY(regs[8]);  COPY(regs[9]);
 232         COPY(regs[10]); COPY(regs[11]);
 233         COPY(regs[12]); COPY(regs[13]);
 234         COPY(regs[14]); COPY(regs[15]);
 235         COPY(gbr);      COPY(mach);
 236         COPY(macl);     COPY(pr);
 237         COPY(sr);       COPY(pc);
 238 #undef COPY
 239
 240 #ifdef CONFIG_SH_FPU
 241         err |= save_sigcontext_fpu(sc, regs);
 242 #endif
 243
 244         /* non-iBCS2 extensions.. */
 245         err |= __put_user(mask, &sc->oldmask);
 246
 247         return err;
 248 }
 249
 250 /*
 251  * Determine which stack to use..
 252  */
 253 static inline void __user *
 254 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 255 {
 256         if (ka->sa.sa_flags & SA_ONSTACK) {
 257                 if (sas_ss_flags(sp) == 0)
 258                         sp = current->sas_ss_sp + current->sas_ss_size;
 259         }
 260
 261         return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
 262 }
 263
 264 /* These symbols are defined with the addresses in the vsyscall page.
 265    See vsyscall-trapa.S.  */
 266 extern void __kernel_sigreturn(void);
 267 extern void __kernel_rt_sigreturn(void);
 268
 269 static int setup_frame(int sig, struct k_sigaction *ka,
 270                         sigset_t *set, struct pt_regs *regs)
 271 {
 272         struct sigframe __user *frame;
 273         int err = 0;
 274         int signal;
 275
 276         frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
 277
 278         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 279                 goto give_sigsegv;
 280
 281         signal = current_thread_info()->exec_domain
 282                 && current_thread_info()->exec_domain->signal_invmap
 283                 && sig < 32
 284                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 285                 : sig;
 286
 287         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
 288
 289         if (_NSIG_WORDS > 1)
 290                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 291                                       sizeof(frame->extramask));
 292
 293         /* Set up to return from userspace.  If provided, use a stub
 294            already in userspace.  */
 295         if (ka->sa.sa_flags & SA_RESTORER) {
 296                 regs->pr = (unsigned long) ka->sa.sa_restorer;
 297 #ifdef CONFIG_VSYSCALL
 298         } else if (likely(current->mm->context.vdso)) {
 299                 regs->pr = VDSO_SYM(&__kernel_sigreturn);
 300 #endif
 301         } else {
 302                 /* Generate return code (system call to sigreturn) */
 303                 err |= __put_user(MOVW(7), &frame->retcode[0]);
 304                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
 305                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
 306                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
 307                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
 308                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
 309                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
 310                 err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
 311                 regs->pr = (unsigned long) frame->retcode;
 312                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
 313         }
 314
 315         if (err)
 316                 goto give_sigsegv;
 317
 318         /* Set up registers for signal handler */
 319         regs->regs[15] = (unsigned long) frame;
 320         regs->regs[4] = signal; /* Arg for signal handler */
 321         regs->regs[5] = 0;
 322         regs->regs[6] = (unsigned long) &frame->sc;
 323
 324         if (current->personality & FDPIC_FUNCPTRS) {
 325                 struct fdpic_func_descriptor __user *funcptr =
 326                         (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
 327
 328                 err |= __get_user(regs->pc, &funcptr->text);
 329                 err |= __get_user(regs->regs[12], &funcptr->GOT);
 330         } else
 331                 regs->pc = (unsigned long)ka->sa.sa_handler;
 332
 333         if (err)
 334                 goto give_sigsegv;
 335
 336         set_fs(USER_DS);
 337
 338         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
 339                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
 340
 341         return 0;
 342
 343 give_sigsegv:
 344         force_sigsegv(sig, current);
 345         return -EFAULT;
 346 }
 347
 348 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 349                            sigset_t *set, struct pt_regs *regs)
 350 {
 351         struct rt_sigframe __user *frame;
 352         int err = 0;
 353         int signal;
 354
 355         frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
 356
 357         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 358                 goto give_sigsegv;
 359
 360         signal = current_thread_info()->exec_domain
 361                 && current_thread_info()->exec_domain->signal_invmap
 362                 && sig < 32
 363                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 364                 : sig;
 365
 366         err |= copy_siginfo_to_user(&frame->info, info);
 367
 368         /* Create the ucontext.  */
 369         err |= __put_user(0, &frame->uc.uc_flags);
 370         err |= __put_user(NULL, &frame->uc.uc_link);
 371         err |= __save_altstack(&frame->uc.uc_stack, regs->regs[15]);
 372         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 373                                 regs, set->sig[0]);
 374         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 375
 376         /* Set up to return from userspace.  If provided, use a stub
 377            already in userspace.  */
 378         if (ka->sa.sa_flags & SA_RESTORER) {
 379                 regs->pr = (unsigned long) ka->sa.sa_restorer;
 380 #ifdef CONFIG_VSYSCALL
 381         } else if (likely(current->mm->context.vdso)) {
 382                 regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
 383 #endif
 384         } else {
 385                 /* Generate return code (system call to rt_sigreturn) */
 386                 err |= __put_user(MOVW(7), &frame->retcode[0]);
 387                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
 388                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
 389                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
 390                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
 391                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
 392                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
 393                 err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
 394                 regs->pr = (unsigned long) frame->retcode;
 395                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
 396         }
 397
 398         if (err)
 399                 goto give_sigsegv;
 400
 401         /* Set up registers for signal handler */
 402         regs->regs[15] = (unsigned long) frame;
 403         regs->regs[4] = signal; /* Arg for signal handler */
 404         regs->regs[5] = (unsigned long) &frame->info;
 405         regs->regs[6] = (unsigned long) &frame->uc;
 406
 407         if (current->personality & FDPIC_FUNCPTRS) {
 408                 struct fdpic_func_descriptor __user *funcptr =
 409                         (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
 410
 411                 err |= __get_user(regs->pc, &funcptr->text);
 412                 err |= __get_user(regs->regs[12], &funcptr->GOT);
 413         } else
 414                 regs->pc = (unsigned long)ka->sa.sa_handler;
 415
 416         if (err)
 417                 goto give_sigsegv;
 418
 419         set_fs(USER_DS);
 420
 421         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
 422                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
 423
 424         return 0;
 425
 426 give_sigsegv:
 427         force_sigsegv(sig, current);
 428         return -EFAULT;
 429 }
 430
 431 static inline void
 432 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
 433                        struct sigaction *sa)
 434 {
 435         /* If we're not from a syscall, bail out */
 436         if (regs->tra < 0)
 437                 return;
 438
 439         /* check for system call restart.. */
 440         switch (regs->regs[0]) {
 441                 case -ERESTART_RESTARTBLOCK:
 442                 case -ERESTARTNOHAND:
 443                 no_system_call_restart:
 444                         regs->regs[0] = -EINTR;
 445                         break;
 446
 447                 case -ERESTARTSYS:
 448                         if (!(sa->sa_flags & SA_RESTART))
 449                                 goto no_system_call_restart;
 450                 /* fallthrough */
 451                 case -ERESTARTNOINTR:
 452                         regs->regs[0] = save_r0;
 453                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 454                         break;
 455         }
 456 }
 457
 458 /*
 459  * OK, we're invoking a handler
 460  */
 461 static void
 462 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 463               struct pt_regs *regs, unsigned int save_r0)
 464 {
 465         sigset_t *oldset = sigmask_to_save();
 466         int ret;
 467
 468         /* Set up the stack frame */
 469         if (ka->sa.sa_flags & SA_SIGINFO)
 470                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 471         else
 472                 ret = setup_frame(sig, ka, oldset, regs);
 473
 474         if (ret)
 475                 return;
 476         signal_delivered(sig, info, ka, regs,
 477                         test_thread_flag(TIF_SINGLESTEP));
 478 }
 479
 480 /*
 481  * Note that 'init' is a special process: it doesn't get signals it doesn't
 482  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 483  * mistake.
 484  *
 485  * Note that we go through the signals twice: once to check the signals that
 486  * the kernel can handle, and then we build all the user-level signal handling
 487  * stack-frames in one go after that.
 488  */
 489 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 490 {
 491         siginfo_t info;
 492         int signr;
 493         struct k_sigaction ka;
 494
 495         /*
 496          * We want the common case to go fast, which
 497          * is why we may in certain cases get here from
 498          * kernel mode. Just return without doing anything
 499          * if so.
 500          */
 501         if (!user_mode(regs))
 502                 return;
 503
 504         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 505         if (signr > 0) {
 506                 handle_syscall_restart(save_r0, regs, &ka.sa);
 507
 508                 /* Whee!  Actually deliver the signal.  */
 509                 handle_signal(signr, &ka, &info, regs, save_r0);
 510                 return;
 511         }
 512
 513         /* Did we come from a system call? */
 514         if (regs->tra >= 0) {
 515                 /* Restart the system call - no handlers present */
 516                 if (regs->regs[0] == -ERESTARTNOHAND ||
 517                     regs->regs[0] == -ERESTARTSYS ||
 518                     regs->regs[0] == -ERESTARTNOINTR) {
 519                         regs->regs[0] = save_r0;
 520                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 521                 } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
 522                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 523                         regs->regs[3] = __NR_restart_syscall;
 524                 }
 525         }
 526
 527         /*
 528          * If there's no signal to deliver, we just put the saved sigmask
 529          * back.
 530          */
 531         restore_saved_sigmask();
 532 }
 533
 534 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
 535                                  unsigned long thread_info_flags)
 536 {
 537         /* deal with pending signal delivery */
 538         if (thread_info_flags & _TIF_SIGPENDING)
 539                 do_signal(regs, save_r0);
 540
 541         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 542                 clear_thread_flag(TIF_NOTIFY_RESUME);
 543                 tracehook_notify_resume(regs);
 544         }
 545 }