arch/unicore32/kernel/signal.c

   1 /*
   2  * linux/arch/unicore32/kernel/signal.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/errno.h>
  13 #include <linux/signal.h>
  14 #include <linux/personality.h>
  15 #include <linux/freezer.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/tracehook.h>
  18 #include <linux/elf.h>
  19 #include <linux/unistd.h>
  20
  21 #include <asm/cacheflush.h>
  22 #include <asm/ucontext.h>
  23
  24 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  25
  26 /*
  27  * For UniCore syscalls, we encode the syscall number into the instruction.
  28  */
  29 #define SWI_SYS_SIGRETURN       (0xff000000) /* error number for new abi */
  30 #define SWI_SYS_RT_SIGRETURN    (0xff000000 | (__NR_rt_sigreturn))
  31 #define SWI_SYS_RESTART         (0xff000000 | (__NR_restart_syscall))
  32
  33 #define KERN_SIGRETURN_CODE     (KUSER_VECPAGE_BASE + 0x00000500)
  34 #define KERN_RESTART_CODE       (KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
  35
  36 const unsigned long sigreturn_codes[3] = {
  37         SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
  38 };
  39
  40 const unsigned long syscall_restart_code[2] = {
  41         SWI_SYS_RESTART,        /* swi  __NR_restart_syscall */
  42         0x69efc004,             /* ldr  pc, [sp], #4 */
  43 };
  44
  45 /*
  46  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
  47  */
  48 struct sigframe {
  49         struct ucontext uc;
  50         unsigned long retcode[2];
  51 };
  52
  53 struct rt_sigframe {
  54         struct siginfo info;
  55         struct sigframe sig;
  56 };
  57
  58 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
  59 {
  60         sigset_t set;
  61         int err;
  62
  63         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
  64         if (err == 0) {
  65                 sigdelsetmask(&set, ~_BLOCKABLE);
  66                 set_current_blocked(&set);
  67         }
  68
  69         err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
  70         err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
  71         err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
  72         err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
  73         err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
  74         err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
  75         err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
  76         err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
  77         err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
  78         err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
  79         err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
  80         err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
  81         err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
  82         err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
  83         err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
  84         err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
  85         err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
  86         err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
  87         err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
  88         err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
  89         err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
  90         err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
  91         err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
  92         err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
  93         err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
  94         err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
  95         err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
  96         err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
  97         err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
  98         err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
  99         err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 100         err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 101         err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 102
 103         err |= !valid_user_regs(regs);
 104
 105         return err;
 106 }
 107
 108 asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
 109 {
 110         struct rt_sigframe __user *frame;
 111
 112         /* Always make any pending restarted system calls return -EINTR */
 113         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 114
 115         /*
 116          * Since we stacked the signal on a 64-bit boundary,
 117          * then 'sp' should be word aligned here.  If it's
 118          * not, then the user is trying to mess with us.
 119          */
 120         if (regs->UCreg_sp & 7)
 121                 goto badframe;
 122
 123         frame = (struct rt_sigframe __user *)regs->UCreg_sp;
 124
 125         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 126                 goto badframe;
 127
 128         if (restore_sigframe(regs, &frame->sig))
 129                 goto badframe;
 130
 131         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
 132                         == -EFAULT)
 133                 goto badframe;
 134
 135         return regs->UCreg_00;
 136
 137 badframe:
 138         force_sig(SIGSEGV, current);
 139         return 0;
 140 }
 141
 142 static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
 143                 sigset_t *set)
 144 {
 145         int err = 0;
 146
 147         err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
 148         err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
 149         err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
 150         err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
 151         err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
 152         err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
 153         err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
 154         err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
 155         err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
 156         err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
 157         err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
 158         err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
 159         err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
 160         err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
 161         err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
 162         err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
 163         err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
 164         err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
 165         err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
 166         err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
 167         err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
 168         err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
 169         err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
 170         err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
 171         err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
 172         err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
 173         err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
 174         err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
 175         err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
 176         err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
 177         err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 178         err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 179         err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 180
 181         err |= __put_user(current->thread.trap_no,
 182                         &sf->uc.uc_mcontext.trap_no);
 183         err |= __put_user(current->thread.error_code,
 184                         &sf->uc.uc_mcontext.error_code);
 185         err |= __put_user(current->thread.address,
 186                         &sf->uc.uc_mcontext.fault_address);
 187         err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
 188
 189         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 190
 191         return err;
 192 }
 193
 194 static inline void __user *get_sigframe(struct k_sigaction *ka,
 195                 struct pt_regs *regs, int framesize)
 196 {
 197         unsigned long sp = regs->UCreg_sp;
 198         void __user *frame;
 199
 200         /*
 201          * This is the X/Open sanctioned signal stack switching.
 202          */
 203         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 204                 sp = current->sas_ss_sp + current->sas_ss_size;
 205
 206         /*
 207          * ATPCS B01 mandates 8-byte alignment
 208          */
 209         frame = (void __user *)((sp - framesize) & ~7);
 210
 211         /*
 212          * Check that we can actually write to the signal frame.
 213          */
 214         if (!access_ok(VERIFY_WRITE, frame, framesize))
 215                 frame = NULL;
 216
 217         return frame;
 218 }
 219
 220 static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 221              unsigned long __user *rc, void __user *frame, int usig)
 222 {
 223         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 224         unsigned long retcode;
 225         unsigned long asr = regs->UCreg_asr & ~PSR_f;
 226
 227         unsigned int idx = 0;
 228
 229         if (ka->sa.sa_flags & SA_SIGINFO)
 230                 idx += 1;
 231
 232         if (__put_user(sigreturn_codes[idx],   rc) ||
 233             __put_user(sigreturn_codes[idx+1], rc+1))
 234                 return 1;
 235
 236         retcode = KERN_SIGRETURN_CODE + (idx << 2);
 237
 238         regs->UCreg_00 = usig;
 239         regs->UCreg_sp = (unsigned long)frame;
 240         regs->UCreg_lr = retcode;
 241         regs->UCreg_pc = handler;
 242         regs->UCreg_asr = asr;
 243
 244         return 0;
 245 }
 246
 247 static int setup_frame(int usig, struct k_sigaction *ka,
 248                 sigset_t *set, struct pt_regs *regs)
 249 {
 250         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 251         int err = 0;
 252
 253         if (!frame)
 254                 return 1;
 255
 256         /*
 257          * Set uc.uc_flags to a value which sc.trap_no would never have.
 258          */
 259         err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
 260
 261         err |= setup_sigframe(frame, regs, set);
 262         if (err == 0)
 263                 err |= setup_return(regs, ka, frame->retcode, frame, usig);
 264
 265         return err;
 266 }
 267
 268 static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 269                sigset_t *set, struct pt_regs *regs)
 270 {
 271         struct rt_sigframe __user *frame =
 272                         get_sigframe(ka, regs, sizeof(*frame));
 273         stack_t stack;
 274         int err = 0;
 275
 276         if (!frame)
 277                 return 1;
 278
 279         err |= copy_siginfo_to_user(&frame->info, info);
 280
 281         err |= __put_user(0, &frame->sig.uc.uc_flags);
 282         err |= __put_user(NULL, &frame->sig.uc.uc_link);
 283
 284         memset(&stack, 0, sizeof(stack));
 285         stack.ss_sp = (void __user *)current->sas_ss_sp;
 286         stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
 287         stack.ss_size = current->sas_ss_size;
 288         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 289
 290         err |= setup_sigframe(&frame->sig, regs, set);
 291         if (err == 0)
 292                 err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);
 293
 294         if (err == 0) {
 295                 /*
 296                  * For realtime signals we must also set the second and third
 297                  * arguments for the signal handler.
 298                  */
 299                 regs->UCreg_01 = (unsigned long)&frame->info;
 300                 regs->UCreg_02 = (unsigned long)&frame->sig.uc;
 301         }
 302
 303         return err;
 304 }
 305
 306 static inline void setup_syscall_restart(struct pt_regs *regs)
 307 {
 308         regs->UCreg_00 = regs->UCreg_ORIG_00;
 309         regs->UCreg_pc -= 4;
 310 }
 311
 312 /*
 313  * OK, we're invoking a handler
 314  */
 315 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 316               siginfo_t *info, sigset_t *oldset,
 317               struct pt_regs *regs, int syscall)
 318 {
 319         struct thread_info *thread = current_thread_info();
 320         struct task_struct *tsk = current;
 321         int usig = sig;
 322         int ret;
 323
 324         /*
 325          * If we were from a system call, check for system call restarting...
 326          */
 327         if (syscall) {
 328                 switch (regs->UCreg_00) {
 329                 case -ERESTART_RESTARTBLOCK:
 330                 case -ERESTARTNOHAND:
 331                         regs->UCreg_00 = -EINTR;
 332                         break;
 333                 case -ERESTARTSYS:
 334                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 335                                 regs->UCreg_00 = -EINTR;
 336                                 break;
 337                         }
 338                         /* fallthrough */
 339                 case -ERESTARTNOINTR:
 340                         setup_syscall_restart(regs);
 341                 }
 342         }
 343
 344         /*
 345          * translate the signal
 346          */
 347         if (usig < 32 && thread->exec_domain
 348                         && thread->exec_domain->signal_invmap)
 349                 usig = thread->exec_domain->signal_invmap[usig];
 350
 351         /*
 352          * Set up the stack frame
 353          */
 354         if (ka->sa.sa_flags & SA_SIGINFO)
 355                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 356         else
 357                 ret = setup_frame(usig, ka, oldset, regs);
 358
 359         /*
 360          * Check that the resulting registers are actually sane.
 361          */
 362         ret |= !valid_user_regs(regs);
 363
 364         if (ret != 0) {
 365                 force_sigsegv(sig, tsk);
 366                 return ret;
 367         }
 368
 369         /*
 370          * Block the signal if we were successful.
 371          */
 372         block_sigmask(ka, sig);
 373
 374         return 0;
 375 }
 376
 377 /*
 378  * Note that 'init' is a special process: it doesn't get signals it doesn't
 379  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 380  * mistake.
 381  *
 382  * Note that we go through the signals twice: once to check the signals that
 383  * the kernel can handle, and then we build all the user-level signal handling
 384  * stack-frames in one go after that.
 385  */
 386 static void do_signal(struct pt_regs *regs, int syscall)
 387 {
 388         struct k_sigaction ka;
 389         siginfo_t info;
 390         int signr;
 391
 392         /*
 393          * We want the common case to go fast, which
 394          * is why we may in certain cases get here from
 395          * kernel mode. Just return without doing anything
 396          * if so.
 397          */
 398         if (!user_mode(regs))
 399                 return;
 400
 401         if (try_to_freeze())
 402                 goto no_signal;
 403
 404         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 405         if (signr > 0) {
 406                 sigset_t *oldset;
 407
 408                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 409                         oldset = &current->saved_sigmask;
 410                 else
 411                         oldset = &current->blocked;
 412                 if (handle_signal(signr, &ka, &info, oldset, regs, syscall)
 413                                 == 0) {
 414                         /*
 415                          * A signal was successfully delivered; the saved
 416                          * sigmask will have been stored in the signal frame,
 417                          * and will be restored by sigreturn, so we can simply
 418                          * clear the TIF_RESTORE_SIGMASK flag.
 419                          */
 420                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 421                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 422                 }
 423                 return;
 424         }
 425
 426  no_signal:
 427         /*
 428          * No signal to deliver to the process - restart the syscall.
 429          */
 430         if (syscall) {
 431                 if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
 432                                 u32 __user *usp;
 433
 434                                 regs->UCreg_sp -= 4;
 435                                 usp = (u32 __user *)regs->UCreg_sp;
 436
 437                                 if (put_user(regs->UCreg_pc, usp) == 0) {
 438                                         regs->UCreg_pc = KERN_RESTART_CODE;
 439                                 } else {
 440                                         regs->UCreg_sp += 4;
 441                                         force_sigsegv(0, current);
 442                                 }
 443                 }
 444                 if (regs->UCreg_00 == -ERESTARTNOHAND ||
 445                     regs->UCreg_00 == -ERESTARTSYS ||
 446                     regs->UCreg_00 == -ERESTARTNOINTR) {
 447                         setup_syscall_restart(regs);
 448                 }
 449
 450                 /* If there's no signal to deliver, we just put the saved
 451                  * sigmask back.
 452                  */
 453                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 454                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 455                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 456                 }
 457         }
 458 }
 459
 460 asmlinkage void do_notify_resume(struct pt_regs *regs,
 461                 unsigned int thread_flags, int syscall)
 462 {
 463         if (thread_flags & _TIF_SIGPENDING)
 464                 do_signal(regs, syscall);
 465
 466         if (thread_flags & _TIF_NOTIFY_RESUME) {
 467                 clear_thread_flag(TIF_NOTIFY_RESUME);
 468                 tracehook_notify_resume(regs);
 469                 if (current->replacement_session_keyring)
 470                         key_replace_session_keyring();
 471         }
 472 }
 473
 474 /*
 475  * Copy signal return handlers into the vector page, and
 476  * set sigreturn to be a pointer to these.
 477  */
 478 void __init early_signal_init(void)
 479 {
 480         memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
 481                         sigreturn_codes, sizeof(sigreturn_codes));
 482         memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
 483                         syscall_restart_code, sizeof(syscall_restart_code));
 484         /* Need not to flush icache, since early_trap_init will do it last. */
 485 }