arch/s390/kernel/signal.c

   1 /*
   2  *    Copyright IBM Corp. 1999, 2006
   3  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   4  *
   5  *    Based on Intel version
   6  *
   7  *  Copyright (C) 1991, 1992  Linus Torvalds
   8  *
   9  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/smp.h>
  15 #include <linux/kernel.h>
  16 #include <linux/signal.h>
  17 #include <linux/errno.h>
  18 #include <linux/wait.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/unistd.h>
  21 #include <linux/stddef.h>
  22 #include <linux/tty.h>
  23 #include <linux/personality.h>
  24 #include <linux/binfmts.h>
  25 #include <linux/tracehook.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/compat.h>
  28 #include <asm/ucontext.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/lowcore.h>
  31 #include <asm/switch_to.h>
  32 #include "entry.h"
  33
  34 typedef struct
  35 {
  36         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  37         struct sigcontext sc;
  38         _sigregs sregs;
  39         int signo;
  40         __u8 retcode[S390_SYSCALL_SIZE];
  41 } sigframe;
  42
  43 typedef struct
  44 {
  45         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  46         __u8 retcode[S390_SYSCALL_SIZE];
  47         struct siginfo info;
  48         struct ucontext uc;
  49 } rt_sigframe;
  50
  51 /* Returns non-zero on fault. */
  52 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
  53 {
  54         _sigregs user_sregs;
  55
  56         save_access_regs(current->thread.acrs);
  57
  58         /* Copy a 'clean' PSW mask to the user to avoid leaking
  59            information about whether PER is currently on.  */
  60         user_sregs.regs.psw.mask = psw_user_bits |
  61                 (regs->psw.mask & PSW_MASK_USER);
  62         user_sregs.regs.psw.addr = regs->psw.addr;
  63         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
  64         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
  65                sizeof(sregs->regs.acrs));
  66         /*
  67          * We have to store the fp registers to current->thread.fp_regs
  68          * to merge them with the emulated registers.
  69          */
  70         save_fp_regs(&current->thread.fp_regs);
  71         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
  72                sizeof(s390_fp_regs));
  73         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
  74 }
  75
  76 /* Returns positive number on error */
  77 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
  78 {
  79         int err;
  80         _sigregs user_sregs;
  81
  82         /* Alwys make any pending restarted system call return -EINTR */
  83         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  84
  85         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
  86         if (err)
  87                 return err;
  88         /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */
  89         regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
  90                 (user_sregs.regs.psw.mask & PSW_MASK_USER);
  91         /* Check for invalid user address space control. */
  92         if ((regs->psw.mask & PSW_MASK_ASC) >= (psw_kernel_bits & PSW_MASK_ASC))
  93                 regs->psw.mask = (psw_user_bits & PSW_MASK_ASC) |
  94                         (regs->psw.mask & ~PSW_MASK_ASC);
  95         /* Check for invalid amode */
  96         if (regs->psw.mask & PSW_MASK_EA)
  97                 regs->psw.mask |= PSW_MASK_BA;
  98         regs->psw.addr = user_sregs.regs.psw.addr;
  99         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 100         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 101                sizeof(sregs->regs.acrs));
 102         restore_access_regs(current->thread.acrs);
 103
 104         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 105                sizeof(s390_fp_regs));
 106         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 107
 108         restore_fp_regs(&current->thread.fp_regs);
 109         clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
 110         return 0;
 111 }
 112
 113 SYSCALL_DEFINE0(sigreturn)
 114 {
 115         struct pt_regs *regs = task_pt_regs(current);
 116         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 117         sigset_t set;
 118
 119         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 120                 goto badframe;
 121         set_current_blocked(&set);
 122         if (restore_sigregs(regs, &frame->sregs))
 123                 goto badframe;
 124         return regs->gprs[2];
 125 badframe:
 126         force_sig(SIGSEGV, current);
 127         return 0;
 128 }
 129
 130 SYSCALL_DEFINE0(rt_sigreturn)
 131 {
 132         struct pt_regs *regs = task_pt_regs(current);
 133         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 134         sigset_t set;
 135
 136         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 137                 goto badframe;
 138         set_current_blocked(&set);
 139         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 140                 goto badframe;
 141         if (restore_altstack(&frame->uc.uc_stack))
 142                 goto badframe;
 143         return regs->gprs[2];
 144 badframe:
 145         force_sig(SIGSEGV, current);
 146         return 0;
 147 }
 148
 149 /*
 150  * Set up a signal frame.
 151  */
 152
 153
 154 /*
 155  * Determine which stack to use..
 156  */
 157 static inline void __user *
 158 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 159 {
 160         unsigned long sp;
 161
 162         /* Default to using normal stack */
 163         sp = regs->gprs[15];
 164
 165         /* Overflow on alternate signal stack gives SIGSEGV. */
 166         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 167                 return (void __user *) -1UL;
 168
 169         /* This is the X/Open sanctioned signal stack switching.  */
 170         if (ka->sa.sa_flags & SA_ONSTACK) {
 171                 if (! sas_ss_flags(sp))
 172                         sp = current->sas_ss_sp + current->sas_ss_size;
 173         }
 174
 175         return (void __user *)((sp - frame_size) & -8ul);
 176 }
 177
 178 static inline int map_signal(int sig)
 179 {
 180         if (current_thread_info()->exec_domain
 181             && current_thread_info()->exec_domain->signal_invmap
 182             && sig < 32)
 183                 return current_thread_info()->exec_domain->signal_invmap[sig];
 184         else
 185                 return sig;
 186 }
 187
 188 static int setup_frame(int sig, struct k_sigaction *ka,
 189                        sigset_t *set, struct pt_regs * regs)
 190 {
 191         sigframe __user *frame;
 192
 193         frame = get_sigframe(ka, regs, sizeof(sigframe));
 194
 195         if (frame == (void __user *) -1UL)
 196                 goto give_sigsegv;
 197
 198         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 199                 goto give_sigsegv;
 200
 201         if (save_sigregs(regs, &frame->sregs))
 202                 goto give_sigsegv;
 203         if (__put_user(&frame->sregs, &frame->sc.sregs))
 204                 goto give_sigsegv;
 205
 206         /* Set up to return from userspace.  If provided, use a stub
 207            already in userspace.  */
 208         if (ka->sa.sa_flags & SA_RESTORER) {
 209                 regs->gprs[14] = (unsigned long)
 210                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 211         } else {
 212                 regs->gprs[14] = (unsigned long)
 213                         frame->retcode | PSW_ADDR_AMODE;
 214                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 215                                (u16 __user *)(frame->retcode)))
 216                         goto give_sigsegv;
 217         }
 218
 219         /* Set up backchain. */
 220         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 221                 goto give_sigsegv;
 222
 223         /* Set up registers for signal handler */
 224         regs->gprs[15] = (unsigned long) frame;
 225         /* Force default amode and default user address space control. */
 226         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 227                 (psw_user_bits & PSW_MASK_ASC) |
 228                 (regs->psw.mask & ~PSW_MASK_ASC);
 229         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 230
 231         regs->gprs[2] = map_signal(sig);
 232         regs->gprs[3] = (unsigned long) &frame->sc;
 233
 234         /* We forgot to include these in the sigcontext.
 235            To avoid breaking binary compatibility, they are passed as args. */
 236         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 237             sig == SIGTRAP || sig == SIGFPE) {
 238                 /* set extra registers only for synchronous signals */
 239                 regs->gprs[4] = regs->int_code & 127;
 240                 regs->gprs[5] = regs->int_parm_long;
 241                 regs->gprs[6] = task_thread_info(current)->last_break;
 242         }
 243
 244         /* Place signal number on stack to allow backtrace from handler.  */
 245         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 246                 goto give_sigsegv;
 247         return 0;
 248
 249 give_sigsegv:
 250         force_sigsegv(sig, current);
 251         return -EFAULT;
 252 }
 253
 254 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 255                            sigset_t *set, struct pt_regs * regs)
 256 {
 257         int err = 0;
 258         rt_sigframe __user *frame;
 259
 260         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 261
 262         if (frame == (void __user *) -1UL)
 263                 goto give_sigsegv;
 264
 265         if (copy_siginfo_to_user(&frame->info, info))
 266                 goto give_sigsegv;
 267
 268         /* Create the ucontext.  */
 269         err |= __put_user(0, &frame->uc.uc_flags);
 270         err |= __put_user(NULL, &frame->uc.uc_link);
 271         err |= __save_altstack(&frame->uc.uc_stack, regs->gprs[15]);
 272         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 273         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 274         if (err)
 275                 goto give_sigsegv;
 276
 277         /* Set up to return from userspace.  If provided, use a stub
 278            already in userspace.  */
 279         if (ka->sa.sa_flags & SA_RESTORER) {
 280                 regs->gprs[14] = (unsigned long)
 281                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 282         } else {
 283                 regs->gprs[14] = (unsigned long)
 284                         frame->retcode | PSW_ADDR_AMODE;
 285                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 286                                (u16 __user *)(frame->retcode)))
 287                         goto give_sigsegv;
 288         }
 289
 290         /* Set up backchain. */
 291         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 292                 goto give_sigsegv;
 293
 294         /* Set up registers for signal handler */
 295         regs->gprs[15] = (unsigned long) frame;
 296         /* Force default amode and default user address space control. */
 297         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 298                 (psw_user_bits & PSW_MASK_ASC) |
 299                 (regs->psw.mask & ~PSW_MASK_ASC);
 300         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 301
 302         regs->gprs[2] = map_signal(sig);
 303         regs->gprs[3] = (unsigned long) &frame->info;
 304         regs->gprs[4] = (unsigned long) &frame->uc;
 305         regs->gprs[5] = task_thread_info(current)->last_break;
 306         return 0;
 307
 308 give_sigsegv:
 309         force_sigsegv(sig, current);
 310         return -EFAULT;
 311 }
 312
 313 static void handle_signal(unsigned long sig, struct k_sigaction *ka,
 314                          siginfo_t *info, sigset_t *oldset,
 315                          struct pt_regs *regs)
 316 {
 317         int ret;
 318
 319         /* Set up the stack frame */
 320         if (ka->sa.sa_flags & SA_SIGINFO)
 321                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 322         else
 323                 ret = setup_frame(sig, ka, oldset, regs);
 324         if (ret)
 325                 return;
 326         signal_delivered(sig, info, ka, regs,
 327                                  test_thread_flag(TIF_SINGLE_STEP));
 328 }
 329
 330 /*
 331  * Note that 'init' is a special process: it doesn't get signals it doesn't
 332  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 333  * mistake.
 334  *
 335  * Note that we go through the signals twice: once to check the signals that
 336  * the kernel can handle, and then we build all the user-level signal handling
 337  * stack-frames in one go after that.
 338  */
 339 void do_signal(struct pt_regs *regs)
 340 {
 341         siginfo_t info;
 342         int signr;
 343         struct k_sigaction ka;
 344         sigset_t *oldset = sigmask_to_save();
 345
 346         /*
 347          * Get signal to deliver. When running under ptrace, at this point
 348          * the debugger may change all our registers, including the system
 349          * call information.
 350          */
 351         current_thread_info()->system_call =
 352                 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
 353         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 354
 355         if (signr > 0) {
 356                 /* Whee!  Actually deliver the signal.  */
 357                 if (current_thread_info()->system_call) {
 358                         regs->int_code = current_thread_info()->system_call;
 359                         /* Check for system call restarting. */
 360                         switch (regs->gprs[2]) {
 361                         case -ERESTART_RESTARTBLOCK:
 362                         case -ERESTARTNOHAND:
 363                                 regs->gprs[2] = -EINTR;
 364                                 break;
 365                         case -ERESTARTSYS:
 366                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 367                                         regs->gprs[2] = -EINTR;
 368                                         break;
 369                                 }
 370                         /* fallthrough */
 371                         case -ERESTARTNOINTR:
 372                                 regs->gprs[2] = regs->orig_gpr2;
 373                                 regs->psw.addr =
 374                                         __rewind_psw(regs->psw,
 375                                                      regs->int_code >> 16);
 376                                 break;
 377                         }
 378                 }
 379                 /* No longer in a system call */
 380                 clear_thread_flag(TIF_SYSCALL);
 381
 382                 if (is_compat_task())
 383                         handle_signal32(signr, &ka, &info, oldset, regs);
 384                 else
 385                         handle_signal(signr, &ka, &info, oldset, regs);
 386                 return;
 387         }
 388
 389         /* No handlers present - check for system call restart */
 390         clear_thread_flag(TIF_SYSCALL);
 391         if (current_thread_info()->system_call) {
 392                 regs->int_code = current_thread_info()->system_call;
 393                 switch (regs->gprs[2]) {
 394                 case -ERESTART_RESTARTBLOCK:
 395                         /* Restart with sys_restart_syscall */
 396                         regs->int_code = __NR_restart_syscall;
 397                 /* fallthrough */
 398                 case -ERESTARTNOHAND:
 399                 case -ERESTARTSYS:
 400                 case -ERESTARTNOINTR:
 401                         /* Restart system call with magic TIF bit. */
 402                         regs->gprs[2] = regs->orig_gpr2;
 403                         set_thread_flag(TIF_SYSCALL);
 404                         if (test_thread_flag(TIF_SINGLE_STEP))
 405                                 set_thread_flag(TIF_PER_TRAP);
 406                         break;
 407                 }
 408         }
 409
 410         /*
 411          * If there's no signal to deliver, we just put the saved sigmask back.
 412          */
 413         restore_saved_sigmask();
 414 }
 415
 416 void do_notify_resume(struct pt_regs *regs)
 417 {
 418         clear_thread_flag(TIF_NOTIFY_RESUME);
 419         tracehook_notify_resume(regs);
 420 }