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->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 (restore_altstack(&frame->sig.uc.uc_stack))
 127                 goto badframe;
 128
 129         return regs->UCreg_00;
 130
 131 badframe:
 132         force_sig(SIGSEGV, current);
 133         return 0;
 134 }
 135
 136 static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
 137                 sigset_t *set)
 138 {
 139         int err = 0;
 140
 141         err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
 142         err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
 143         err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
 144         err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
 145         err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
 146         err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
 147         err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
 148         err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
 149         err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
 150         err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
 151         err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
 152         err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
 153         err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
 154         err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
 155         err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
 156         err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
 157         err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
 158         err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
 159         err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
 160         err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
 161         err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
 162         err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
 163         err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
 164         err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
 165         err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
 166         err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
 167         err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
 168         err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
 169         err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
 170         err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
 171         err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
 172         err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
 173         err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
 174
 175         err |= __put_user(current->thread.trap_no,
 176                         &sf->uc.uc_mcontext.trap_no);
 177         err |= __put_user(current->thread.error_code,
 178                         &sf->uc.uc_mcontext.error_code);
 179         err |= __put_user(current->thread.address,
 180                         &sf->uc.uc_mcontext.fault_address);
 181         err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
 182
 183         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 184
 185         return err;
 186 }
 187
 188 static inline void __user *get_sigframe(struct k_sigaction *ka,
 189                 struct pt_regs *regs, int framesize)
 190 {
 191         unsigned long sp = regs->UCreg_sp;
 192         void __user *frame;
 193
 194         /*
 195          * This is the X/Open sanctioned signal stack switching.
 196          */
 197         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 198                 sp = current->sas_ss_sp + current->sas_ss_size;
 199
 200         /*
 201          * ATPCS B01 mandates 8-byte alignment
 202          */
 203         frame = (void __user *)((sp - framesize) & ~7);
 204
 205         /*
 206          * Check that we can actually write to the signal frame.
 207          */
 208         if (!access_ok(VERIFY_WRITE, frame, framesize))
 209                 frame = NULL;
 210
 211         return frame;
 212 }
 213
 214 static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 215              unsigned long __user *rc, void __user *frame, int usig)
 216 {
 217         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 218         unsigned long retcode;
 219         unsigned long asr = regs->UCreg_asr & ~PSR_f;
 220
 221         unsigned int idx = 0;
 222
 223         if (ka->sa.sa_flags & SA_SIGINFO)
 224                 idx += 1;
 225
 226         if (__put_user(sigreturn_codes[idx],   rc) ||
 227             __put_user(sigreturn_codes[idx+1], rc+1))
 228                 return 1;
 229
 230         retcode = KERN_SIGRETURN_CODE + (idx << 2);
 231
 232         regs->UCreg_00 = usig;
 233         regs->UCreg_sp = (unsigned long)frame;
 234         regs->UCreg_lr = retcode;
 235         regs->UCreg_pc = handler;
 236         regs->UCreg_asr = asr;
 237
 238         return 0;
 239 }
 240
 241 static int setup_frame(struct ksignal *ksig, sigset_t *set,
 242                        struct pt_regs *regs)
 243 {
 244         struct sigframe __user *frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
 245         int err = 0;
 246
 247         if (!frame)
 248                 return 1;
 249
 250         /*
 251          * Set uc.uc_flags to a value which sc.trap_no would never have.
 252          */
 253         err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
 254
 255         err |= setup_sigframe(frame, regs, set);
 256         if (err == 0)
 257                 err |= setup_return(regs, &ksig->ka, frame->retcode, frame,
 258                                     ksig->sig);
 259
 260         return err;
 261 }
 262
 263 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 264                           struct pt_regs *regs)
 265 {
 266         struct rt_sigframe __user *frame =
 267                         get_sigframe(&ksig->ka, regs, sizeof(*frame));
 268         int err = 0;
 269
 270         if (!frame)
 271                 return 1;
 272
 273         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 274
 275         err |= __put_user(0, &frame->sig.uc.uc_flags);
 276         err |= __put_user(NULL, &frame->sig.uc.uc_link);
 277         err |= __save_altstack(&frame->sig.uc.uc_stack, regs->UCreg_sp);
 278         err |= setup_sigframe(&frame->sig, regs, set);
 279         if (err == 0)
 280                 err |= setup_return(regs, &ksig->ka, frame->sig.retcode, frame,
 281                                     ksig->sig);
 282
 283         if (err == 0) {
 284                 /*
 285                  * For realtime signals we must also set the second and third
 286                  * arguments for the signal handler.
 287                  */
 288                 regs->UCreg_01 = (unsigned long)&frame->info;
 289                 regs->UCreg_02 = (unsigned long)&frame->sig.uc;
 290         }
 291
 292         return err;
 293 }
 294
 295 static inline void setup_syscall_restart(struct pt_regs *regs)
 296 {
 297         regs->UCreg_00 = regs->UCreg_ORIG_00;
 298         regs->UCreg_pc -= 4;
 299 }
 300
 301 /*
 302  * OK, we're invoking a handler
 303  */
 304 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
 305                           int syscall)
 306 {
 307         struct thread_info *thread = current_thread_info();
 308         sigset_t *oldset = sigmask_to_save();
 309         int usig = ksig->sig;
 310         int ret;
 311
 312         /*
 313          * If we were from a system call, check for system call restarting...
 314          */
 315         if (syscall) {
 316                 switch (regs->UCreg_00) {
 317                 case -ERESTART_RESTARTBLOCK:
 318                 case -ERESTARTNOHAND:
 319                         regs->UCreg_00 = -EINTR;
 320                         break;
 321                 case -ERESTARTSYS:
 322                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 323                                 regs->UCreg_00 = -EINTR;
 324                                 break;
 325                         }
 326                         /* fallthrough */
 327                 case -ERESTARTNOINTR:
 328                         setup_syscall_restart(regs);
 329                 }
 330         }
 331
 332         /*
 333          * Set up the stack frame
 334          */
 335         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 336                 ret = setup_rt_frame(ksig, oldset, regs);
 337         else
 338                 ret = setup_frame(ksig, oldset, regs);
 339
 340         /*
 341          * Check that the resulting registers are actually sane.
 342          */
 343         ret |= !valid_user_regs(regs);
 344
 345         signal_setup_done(ret, ksig, 0);
 346 }
 347
 348 /*
 349  * Note that 'init' is a special process: it doesn't get signals it doesn't
 350  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 351  * mistake.
 352  *
 353  * Note that we go through the signals twice: once to check the signals that
 354  * the kernel can handle, and then we build all the user-level signal handling
 355  * stack-frames in one go after that.
 356  */
 357 static void do_signal(struct pt_regs *regs, int syscall)
 358 {
 359         struct ksignal ksig;
 360
 361         /*
 362          * We want the common case to go fast, which
 363          * is why we may in certain cases get here from
 364          * kernel mode. Just return without doing anything
 365          * if so.
 366          */
 367         if (!user_mode(regs))
 368                 return;
 369
 370         if (get_signal(&ksig)) {
 371                 handle_signal(&ksig, regs, syscall);
 372                 return;
 373         }
 374
 375         /*
 376          * No signal to deliver to the process - restart the syscall.
 377          */
 378         if (syscall) {
 379                 if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
 380                                 u32 __user *usp;
 381
 382                                 regs->UCreg_sp -= 4;
 383                                 usp = (u32 __user *)regs->UCreg_sp;
 384
 385                                 if (put_user(regs->UCreg_pc, usp) == 0) {
 386                                         regs->UCreg_pc = KERN_RESTART_CODE;
 387                                 } else {
 388                                         regs->UCreg_sp += 4;
 389                                         force_sigsegv(0, current);
 390                                 }
 391                 }
 392                 if (regs->UCreg_00 == -ERESTARTNOHAND ||
 393                     regs->UCreg_00 == -ERESTARTSYS ||
 394                     regs->UCreg_00 == -ERESTARTNOINTR) {
 395                         setup_syscall_restart(regs);
 396                 }
 397         }
 398         /* If there's no signal to deliver, we just put the saved
 399          * sigmask back.
 400          */
 401         restore_saved_sigmask();
 402 }
 403
 404 asmlinkage void do_notify_resume(struct pt_regs *regs,
 405                 unsigned int thread_flags, int syscall)
 406 {
 407         if (thread_flags & _TIF_SIGPENDING)
 408                 do_signal(regs, syscall);
 409
 410         if (thread_flags & _TIF_NOTIFY_RESUME) {
 411                 clear_thread_flag(TIF_NOTIFY_RESUME);
 412                 tracehook_notify_resume(regs);
 413         }
 414 }
 415
 416 /*
 417  * Copy signal return handlers into the vector page, and
 418  * set sigreturn to be a pointer to these.
 419  */
 420 void __init early_signal_init(void)
 421 {
 422         memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
 423                         sigreturn_codes, sizeof(sigreturn_codes));
 424         memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
 425                         syscall_restart_code, sizeof(syscall_restart_code));
 426         /* Need not to flush icache, since early_trap_init will do it last. */
 427 }