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                 spin_lock_irq(&current->sighand->siglock);
  67                 current->blocked = set;
  68                 recalc_sigpending();
  69                 spin_unlock_irq(&current->sighand->siglock);
  70         }
  71
  72         err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
  73         err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
  74         err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
  75         err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
  76         err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
  77         err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
  78         err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
  79         err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
  80         err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
  81         err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
  82         err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
  83         err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
  84         err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
  85         err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
  86         err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
  87         err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
  88         err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
  89         err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
  90         err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
  91         err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
  92         err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
  93         err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
  94         err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
  95         err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
  96         err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
  97         err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
  98         err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
  99         err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
 100         err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
 101         err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
 102         err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 103         err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 104         err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 105
 106         err |= !valid_user_regs(regs);
 107
 108         return err;
 109 }
 110
 111 asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
 112 {
 113         struct rt_sigframe __user *frame;
 114
 115         /* Always make any pending restarted system calls return -EINTR */
 116         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 117
 118         /*
 119          * Since we stacked the signal on a 64-bit boundary,
 120          * then 'sp' should be word aligned here.  If it's
 121          * not, then the user is trying to mess with us.
 122          */
 123         if (regs->UCreg_sp & 7)
 124                 goto badframe;
 125
 126         frame = (struct rt_sigframe __user *)regs->UCreg_sp;
 127
 128         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 129                 goto badframe;
 130
 131         if (restore_sigframe(regs, &frame->sig))
 132                 goto badframe;
 133
 134         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
 135                         == -EFAULT)
 136                 goto badframe;
 137
 138         return regs->UCreg_00;
 139
 140 badframe:
 141         force_sig(SIGSEGV, current);
 142         return 0;
 143 }
 144
 145 static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
 146                 sigset_t *set)
 147 {
 148         int err = 0;
 149
 150         err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
 151         err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
 152         err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
 153         err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
 154         err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
 155         err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
 156         err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
 157         err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
 158         err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
 159         err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
 160         err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
 161         err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
 162         err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
 163         err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
 164         err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
 165         err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
 166         err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
 167         err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
 168         err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
 169         err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
 170         err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
 171         err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
 172         err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
 173         err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
 174         err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
 175         err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
 176         err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
 177         err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
 178         err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
 179         err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
 180         err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 181         err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 182         err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 183
 184         err |= __put_user(current->thread.trap_no,
 185                         &sf->uc.uc_mcontext.trap_no);
 186         err |= __put_user(current->thread.error_code,
 187                         &sf->uc.uc_mcontext.error_code);
 188         err |= __put_user(current->thread.address,
 189                         &sf->uc.uc_mcontext.fault_address);
 190         err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
 191
 192         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 193
 194         return err;
 195 }
 196
 197 static inline void __user *get_sigframe(struct k_sigaction *ka,
 198                 struct pt_regs *regs, int framesize)
 199 {
 200         unsigned long sp = regs->UCreg_sp;
 201         void __user *frame;
 202
 203         /*
 204          * This is the X/Open sanctioned signal stack switching.
 205          */
 206         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 207                 sp = current->sas_ss_sp + current->sas_ss_size;
 208
 209         /*
 210          * ATPCS B01 mandates 8-byte alignment
 211          */
 212         frame = (void __user *)((sp - framesize) & ~7);
 213
 214         /*
 215          * Check that we can actually write to the signal frame.
 216          */
 217         if (!access_ok(VERIFY_WRITE, frame, framesize))
 218                 frame = NULL;
 219
 220         return frame;
 221 }
 222
 223 static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 224              unsigned long __user *rc, void __user *frame, int usig)
 225 {
 226         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 227         unsigned long retcode;
 228         unsigned long asr = regs->UCreg_asr & ~PSR_f;
 229
 230         unsigned int idx = 0;
 231
 232         if (ka->sa.sa_flags & SA_SIGINFO)
 233                 idx += 1;
 234
 235         if (__put_user(sigreturn_codes[idx],   rc) ||
 236             __put_user(sigreturn_codes[idx+1], rc+1))
 237                 return 1;
 238
 239         retcode = KERN_SIGRETURN_CODE + (idx << 2);
 240
 241         regs->UCreg_00 = usig;
 242         regs->UCreg_sp = (unsigned long)frame;
 243         regs->UCreg_lr = retcode;
 244         regs->UCreg_pc = handler;
 245         regs->UCreg_asr = asr;
 246
 247         return 0;
 248 }
 249
 250 static int setup_frame(int usig, struct k_sigaction *ka,
 251                 sigset_t *set, struct pt_regs *regs)
 252 {
 253         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 254         int err = 0;
 255
 256         if (!frame)
 257                 return 1;
 258
 259         /*
 260          * Set uc.uc_flags to a value which sc.trap_no would never have.
 261          */
 262         err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
 263
 264         err |= setup_sigframe(frame, regs, set);
 265         if (err == 0)
 266                 err |= setup_return(regs, ka, frame->retcode, frame, usig);
 267
 268         return err;
 269 }
 270
 271 static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 272                sigset_t *set, struct pt_regs *regs)
 273 {
 274         struct rt_sigframe __user *frame =
 275                         get_sigframe(ka, regs, sizeof(*frame));
 276         stack_t stack;
 277         int err = 0;
 278
 279         if (!frame)
 280                 return 1;
 281
 282         err |= copy_siginfo_to_user(&frame->info, info);
 283
 284         err |= __put_user(0, &frame->sig.uc.uc_flags);
 285         err |= __put_user(NULL, &frame->sig.uc.uc_link);
 286
 287         memset(&stack, 0, sizeof(stack));
 288         stack.ss_sp = (void __user *)current->sas_ss_sp;
 289         stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
 290         stack.ss_size = current->sas_ss_size;
 291         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 292
 293         err |= setup_sigframe(&frame->sig, regs, set);
 294         if (err == 0)
 295                 err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);
 296
 297         if (err == 0) {
 298                 /*
 299                  * For realtime signals we must also set the second and third
 300                  * arguments for the signal handler.
 301                  */
 302                 regs->UCreg_01 = (unsigned long)&frame->info;
 303                 regs->UCreg_02 = (unsigned long)&frame->sig.uc;
 304         }
 305
 306         return err;
 307 }
 308
 309 static inline void setup_syscall_restart(struct pt_regs *regs)
 310 {
 311         regs->UCreg_00 = regs->UCreg_ORIG_00;
 312         regs->UCreg_pc -= 4;
 313 }
 314
 315 /*
 316  * OK, we're invoking a handler
 317  */
 318 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 319               siginfo_t *info, sigset_t *oldset,
 320               struct pt_regs *regs, int syscall)
 321 {
 322         struct thread_info *thread = current_thread_info();
 323         struct task_struct *tsk = current;
 324         int usig = sig;
 325         int ret;
 326
 327         /*
 328          * If we were from a system call, check for system call restarting...
 329          */
 330         if (syscall) {
 331                 switch (regs->UCreg_00) {
 332                 case -ERESTART_RESTARTBLOCK:
 333                 case -ERESTARTNOHAND:
 334                         regs->UCreg_00 = -EINTR;
 335                         break;
 336                 case -ERESTARTSYS:
 337                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 338                                 regs->UCreg_00 = -EINTR;
 339                                 break;
 340                         }
 341                         /* fallthrough */
 342                 case -ERESTARTNOINTR:
 343                         setup_syscall_restart(regs);
 344                 }
 345         }
 346
 347         /*
 348          * translate the signal
 349          */
 350         if (usig < 32 && thread->exec_domain
 351                         && thread->exec_domain->signal_invmap)
 352                 usig = thread->exec_domain->signal_invmap[usig];
 353
 354         /*
 355          * Set up the stack frame
 356          */
 357         if (ka->sa.sa_flags & SA_SIGINFO)
 358                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 359         else
 360                 ret = setup_frame(usig, ka, oldset, regs);
 361
 362         /*
 363          * Check that the resulting registers are actually sane.
 364          */
 365         ret |= !valid_user_regs(regs);
 366
 367         if (ret != 0) {
 368                 force_sigsegv(sig, tsk);
 369                 return ret;
 370         }
 371
 372         /*
 373          * Block the signal if we were successful.
 374          */
 375         spin_lock_irq(&tsk->sighand->siglock);
 376         sigorsets(&tsk->blocked, &tsk->blocked,
 377                   &ka->sa.sa_mask);
 378         if (!(ka->sa.sa_flags & SA_NODEFER))
 379                 sigaddset(&tsk->blocked, sig);
 380         recalc_sigpending();
 381         spin_unlock_irq(&tsk->sighand->siglock);
 382
 383         return 0;
 384 }
 385
 386 /*
 387  * Note that 'init' is a special process: it doesn't get signals it doesn't
 388  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 389  * mistake.
 390  *
 391  * Note that we go through the signals twice: once to check the signals that
 392  * the kernel can handle, and then we build all the user-level signal handling
 393  * stack-frames in one go after that.
 394  */
 395 static void do_signal(struct pt_regs *regs, int syscall)
 396 {
 397         struct k_sigaction ka;
 398         siginfo_t info;
 399         int signr;
 400
 401         /*
 402          * We want the common case to go fast, which
 403          * is why we may in certain cases get here from
 404          * kernel mode. Just return without doing anything
 405          * if so.
 406          */
 407         if (!user_mode(regs))
 408                 return;
 409
 410         if (try_to_freeze())
 411                 goto no_signal;
 412
 413         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 414         if (signr > 0) {
 415                 sigset_t *oldset;
 416
 417                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 418                         oldset = &current->saved_sigmask;
 419                 else
 420                         oldset = &current->blocked;
 421                 if (handle_signal(signr, &ka, &info, oldset, regs, syscall)
 422                                 == 0) {
 423                         /*
 424                          * A signal was successfully delivered; the saved
 425                          * sigmask will have been stored in the signal frame,
 426                          * and will be restored by sigreturn, so we can simply
 427                          * clear the TIF_RESTORE_SIGMASK flag.
 428                          */
 429                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 430                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 431                 }
 432                 return;
 433         }
 434
 435  no_signal:
 436         /*
 437          * No signal to deliver to the process - restart the syscall.
 438          */
 439         if (syscall) {
 440                 if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
 441                                 u32 __user *usp;
 442
 443                                 regs->UCreg_sp -= 4;
 444                                 usp = (u32 __user *)regs->UCreg_sp;
 445
 446                                 if (put_user(regs->UCreg_pc, usp) == 0) {
 447                                         regs->UCreg_pc = KERN_RESTART_CODE;
 448                                 } else {
 449                                         regs->UCreg_sp += 4;
 450                                         force_sigsegv(0, current);
 451                                 }
 452                 }
 453                 if (regs->UCreg_00 == -ERESTARTNOHAND ||
 454                     regs->UCreg_00 == -ERESTARTSYS ||
 455                     regs->UCreg_00 == -ERESTARTNOINTR) {
 456                         setup_syscall_restart(regs);
 457                 }
 458
 459                 /* If there's no signal to deliver, we just put the saved
 460                  * sigmask back.
 461                  */
 462                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 463                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 464                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 465                 }
 466         }
 467 }
 468
 469 asmlinkage void do_notify_resume(struct pt_regs *regs,
 470                 unsigned int thread_flags, int syscall)
 471 {
 472         if (thread_flags & _TIF_SIGPENDING)
 473                 do_signal(regs, syscall);
 474
 475         if (thread_flags & _TIF_NOTIFY_RESUME) {
 476                 clear_thread_flag(TIF_NOTIFY_RESUME);
 477                 tracehook_notify_resume(regs);
 478                 if (current->replacement_session_keyring)
 479                         key_replace_session_keyring();
 480         }
 481 }
 482
 483 /*
 484  * Copy signal return handlers into the vector page, and
 485  * set sigreturn to be a pointer to these.
 486  */
 487 void __init early_signal_init(void)
 488 {
 489         memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
 490                         sigreturn_codes, sizeof(sigreturn_codes));
 491         memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
 492                         syscall_restart_code, sizeof(syscall_restart_code));
 493         /* Need not to flush icache, since early_trap_init will do it last. */
 494 }