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