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 | PSW_MASK_RI));
  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(user_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_ctl(&current->thread.fp_regs.fpc);
  71         save_fp_regs(current->thread.fp_regs.fprs);
  72         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
  73                sizeof(user_sregs.fpregs));
  74         if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
  75                 return -EFAULT;
  76         return 0;
  77 }
  78
  79 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
  80 {
  81         _sigregs user_sregs;
  82
  83         /* Alwys make any pending restarted system call return -EINTR */
  84         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  85
  86         if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
  87                 return -EFAULT;
  88
  89         if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
  90                 return -EINVAL;
  91
  92         /* Loading the floating-point-control word can fail. Do that first. */
  93         if (restore_fp_ctl(&user_sregs.fpregs.fpc))
  94                 return -EINVAL;
  95
  96         /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
  97         regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
  98                 (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
  99         /* Check for invalid user address space control. */
 100         if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
 101                 regs->psw.mask = PSW_ASC_PRIMARY |
 102                         (regs->psw.mask & ~PSW_MASK_ASC);
 103         /* Check for invalid amode */
 104         if (regs->psw.mask & PSW_MASK_EA)
 105                 regs->psw.mask |= PSW_MASK_BA;
 106         regs->psw.addr = user_sregs.regs.psw.addr;
 107         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 108         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 109                sizeof(current->thread.acrs));
 110         restore_access_regs(current->thread.acrs);
 111
 112         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 113                sizeof(current->thread.fp_regs));
 114
 115         restore_fp_regs(current->thread.fp_regs.fprs);
 116         clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
 117         return 0;
 118 }
 119
 120 SYSCALL_DEFINE0(sigreturn)
 121 {
 122         struct pt_regs *regs = task_pt_regs(current);
 123         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 124         sigset_t set;
 125
 126         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 127                 goto badframe;
 128         set_current_blocked(&set);
 129         if (restore_sigregs(regs, &frame->sregs))
 130                 goto badframe;
 131         return regs->gprs[2];
 132 badframe:
 133         force_sig(SIGSEGV, current);
 134         return 0;
 135 }
 136
 137 SYSCALL_DEFINE0(rt_sigreturn)
 138 {
 139         struct pt_regs *regs = task_pt_regs(current);
 140         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 141         sigset_t set;
 142
 143         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 144                 goto badframe;
 145         set_current_blocked(&set);
 146         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 147                 goto badframe;
 148         if (restore_altstack(&frame->uc.uc_stack))
 149                 goto badframe;
 150         return regs->gprs[2];
 151 badframe:
 152         force_sig(SIGSEGV, current);
 153         return 0;
 154 }
 155
 156 /*
 157  * Set up a signal frame.
 158  */
 159
 160
 161 /*
 162  * Determine which stack to use..
 163  */
 164 static inline void __user *
 165 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 166 {
 167         unsigned long sp;
 168
 169         /* Default to using normal stack */
 170         sp = regs->gprs[15];
 171
 172         /* Overflow on alternate signal stack gives SIGSEGV. */
 173         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 174                 return (void __user *) -1UL;
 175
 176         /* This is the X/Open sanctioned signal stack switching.  */
 177         if (ka->sa.sa_flags & SA_ONSTACK) {
 178                 if (! sas_ss_flags(sp))
 179                         sp = current->sas_ss_sp + current->sas_ss_size;
 180         }
 181
 182         return (void __user *)((sp - frame_size) & -8ul);
 183 }
 184
 185 static inline int map_signal(int sig)
 186 {
 187         if (current_thread_info()->exec_domain
 188             && current_thread_info()->exec_domain->signal_invmap
 189             && sig < 32)
 190                 return current_thread_info()->exec_domain->signal_invmap[sig];
 191         else
 192                 return sig;
 193 }
 194
 195 static int setup_frame(int sig, struct k_sigaction *ka,
 196                        sigset_t *set, struct pt_regs * regs)
 197 {
 198         sigframe __user *frame;
 199
 200         frame = get_sigframe(ka, regs, sizeof(sigframe));
 201
 202         if (frame == (void __user *) -1UL)
 203                 return -EFAULT;
 204
 205         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 206                 return -EFAULT;
 207
 208         if (save_sigregs(regs, &frame->sregs))
 209                 return -EFAULT;
 210         if (__put_user(&frame->sregs, &frame->sc.sregs))
 211                 return -EFAULT;
 212
 213         /* Set up to return from userspace.  If provided, use a stub
 214            already in userspace.  */
 215         if (ka->sa.sa_flags & SA_RESTORER) {
 216                 regs->gprs[14] = (unsigned long)
 217                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 218         } else {
 219                 regs->gprs[14] = (unsigned long)
 220                         frame->retcode | PSW_ADDR_AMODE;
 221                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 222                                (u16 __user *)(frame->retcode)))
 223                         return -EFAULT;
 224         }
 225
 226         /* Set up backchain. */
 227         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 228                 return -EFAULT;
 229
 230         /* Set up registers for signal handler */
 231         regs->gprs[15] = (unsigned long) frame;
 232         /* Force default amode and default user address space control. */
 233         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 234                 (PSW_USER_BITS & PSW_MASK_ASC) |
 235                 (regs->psw.mask & ~PSW_MASK_ASC);
 236         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 237
 238         regs->gprs[2] = map_signal(sig);
 239         regs->gprs[3] = (unsigned long) &frame->sc;
 240
 241         /* We forgot to include these in the sigcontext.
 242            To avoid breaking binary compatibility, they are passed as args. */
 243         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 244             sig == SIGTRAP || sig == SIGFPE) {
 245                 /* set extra registers only for synchronous signals */
 246                 regs->gprs[4] = regs->int_code & 127;
 247                 regs->gprs[5] = regs->int_parm_long;
 248                 regs->gprs[6] = task_thread_info(current)->last_break;
 249         }
 250
 251         /* Place signal number on stack to allow backtrace from handler.  */
 252         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 253                 return -EFAULT;
 254         return 0;
 255 }
 256
 257 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 258                           struct pt_regs *regs)
 259 {
 260         int err = 0;
 261         rt_sigframe __user *frame;
 262
 263         frame = get_sigframe(&ksig->ka, regs, sizeof(rt_sigframe));
 264
 265         if (frame == (void __user *) -1UL)
 266                 return -EFAULT;
 267
 268         if (copy_siginfo_to_user(&frame->info, &ksig->info))
 269                 return -EFAULT;
 270
 271         /* Create the ucontext.  */
 272         err |= __put_user(0, &frame->uc.uc_flags);
 273         err |= __put_user(NULL, &frame->uc.uc_link);
 274         err |= __save_altstack(&frame->uc.uc_stack, regs->gprs[15]);
 275         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 276         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 277         if (err)
 278                 return -EFAULT;
 279
 280         /* Set up to return from userspace.  If provided, use a stub
 281            already in userspace.  */
 282         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 283                 regs->gprs[14] = (unsigned long)
 284                         ksig->ka.sa.sa_restorer | PSW_ADDR_AMODE;
 285         } else {
 286                 regs->gprs[14] = (unsigned long)
 287                         frame->retcode | PSW_ADDR_AMODE;
 288                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 289                                (u16 __user *)(frame->retcode)))
 290                         return -EFAULT;
 291         }
 292
 293         /* Set up backchain. */
 294         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 295                 return -EFAULT;
 296
 297         /* Set up registers for signal handler */
 298         regs->gprs[15] = (unsigned long) frame;
 299         /* Force default amode and default user address space control. */
 300         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 301                 (PSW_USER_BITS & PSW_MASK_ASC) |
 302                 (regs->psw.mask & ~PSW_MASK_ASC);
 303         regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler | PSW_ADDR_AMODE;
 304
 305         regs->gprs[2] = map_signal(ksig->sig);
 306         regs->gprs[3] = (unsigned long) &frame->info;
 307         regs->gprs[4] = (unsigned long) &frame->uc;
 308         regs->gprs[5] = task_thread_info(current)->last_break;
 309         return 0;
 310 }
 311
 312 static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
 313                           struct pt_regs *regs)
 314 {
 315         int ret;
 316
 317         /* Set up the stack frame */
 318         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 319                 ret = setup_rt_frame(ksig, oldset, regs);
 320         else
 321                 ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);
 322
 323         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
 324 }
 325
 326 /*
 327  * Note that 'init' is a special process: it doesn't get signals it doesn't
 328  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 329  * mistake.
 330  *
 331  * Note that we go through the signals twice: once to check the signals that
 332  * the kernel can handle, and then we build all the user-level signal handling
 333  * stack-frames in one go after that.
 334  */
 335 void do_signal(struct pt_regs *regs)
 336 {
 337         struct ksignal ksig;
 338         sigset_t *oldset = sigmask_to_save();
 339
 340         /*
 341          * Get signal to deliver. When running under ptrace, at this point
 342          * the debugger may change all our registers, including the system
 343          * call information.
 344          */
 345         current_thread_info()->system_call =
 346                 test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
 347
 348         if (get_signal(&ksig)) {
 349                 /* Whee!  Actually deliver the signal.  */
 350                 if (current_thread_info()->system_call) {
 351                         regs->int_code = current_thread_info()->system_call;
 352                         /* Check for system call restarting. */
 353                         switch (regs->gprs[2]) {
 354                         case -ERESTART_RESTARTBLOCK:
 355                         case -ERESTARTNOHAND:
 356                                 regs->gprs[2] = -EINTR;
 357                                 break;
 358                         case -ERESTARTSYS:
 359                                 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
 360                                         regs->gprs[2] = -EINTR;
 361                                         break;
 362                                 }
 363                         /* fallthrough */
 364                         case -ERESTARTNOINTR:
 365                                 regs->gprs[2] = regs->orig_gpr2;
 366                                 regs->psw.addr =
 367                                         __rewind_psw(regs->psw,
 368                                                      regs->int_code >> 16);
 369                                 break;
 370                         }
 371                 }
 372                 /* No longer in a system call */
 373                 clear_pt_regs_flag(regs, PIF_SYSCALL);
 374
 375                 if (is_compat_task())
 376                         handle_signal32(&ksig, oldset, regs);
 377                 else
 378                         handle_signal(&ksig, oldset, regs);
 379                 return;
 380         }
 381
 382         /* No handlers present - check for system call restart */
 383         clear_pt_regs_flag(regs, PIF_SYSCALL);
 384         if (current_thread_info()->system_call) {
 385                 regs->int_code = current_thread_info()->system_call;
 386                 switch (regs->gprs[2]) {
 387                 case -ERESTART_RESTARTBLOCK:
 388                         /* Restart with sys_restart_syscall */
 389                         regs->int_code = __NR_restart_syscall;
 390                 /* fallthrough */
 391                 case -ERESTARTNOHAND:
 392                 case -ERESTARTSYS:
 393                 case -ERESTARTNOINTR:
 394                         /* Restart system call with magic TIF bit. */
 395                         regs->gprs[2] = regs->orig_gpr2;
 396                         set_pt_regs_flag(regs, PIF_SYSCALL);
 397                         if (test_thread_flag(TIF_SINGLE_STEP))
 398                                 clear_pt_regs_flag(regs, PIF_PER_TRAP);
 399                         break;
 400                 }
 401         }
 402
 403         /*
 404          * If there's no signal to deliver, we just put the saved sigmask back.
 405          */
 406         restore_saved_sigmask();
 407 }
 408
 409 void do_notify_resume(struct pt_regs *regs)
 410 {
 411         clear_thread_flag(TIF_NOTIFY_RESUME);
 412         tracehook_notify_resume(regs);
 413 }