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                 goto give_sigsegv;
 204
 205         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 206                 goto give_sigsegv;
 207
 208         if (save_sigregs(regs, &frame->sregs))
 209                 goto give_sigsegv;
 210         if (__put_user(&frame->sregs, &frame->sc.sregs))
 211                 goto give_sigsegv;
 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                         goto give_sigsegv;
 224         }
 225
 226         /* Set up backchain. */
 227         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 228                 goto give_sigsegv;
 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                 goto give_sigsegv;
 254         return 0;
 255
 256 give_sigsegv:
 257         force_sigsegv(sig, current);
 258         return -EFAULT;
 259 }
 260
 261 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 262                            sigset_t *set, struct pt_regs * regs)
 263 {
 264         int err = 0;
 265         rt_sigframe __user *frame;
 266
 267         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 268
 269         if (frame == (void __user *) -1UL)
 270                 goto give_sigsegv;
 271
 272         if (copy_siginfo_to_user(&frame->info, info))
 273                 goto give_sigsegv;
 274
 275         /* Create the ucontext.  */
 276         err |= __put_user(0, &frame->uc.uc_flags);
 277         err |= __put_user(NULL, &frame->uc.uc_link);
 278         err |= __save_altstack(&frame->uc.uc_stack, regs->gprs[15]);
 279         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 280         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 281         if (err)
 282                 goto give_sigsegv;
 283
 284         /* Set up to return from userspace.  If provided, use a stub
 285            already in userspace.  */
 286         if (ka->sa.sa_flags & SA_RESTORER) {
 287                 regs->gprs[14] = (unsigned long)
 288                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 289         } else {
 290                 regs->gprs[14] = (unsigned long)
 291                         frame->retcode | PSW_ADDR_AMODE;
 292                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 293                                (u16 __user *)(frame->retcode)))
 294                         goto give_sigsegv;
 295         }
 296
 297         /* Set up backchain. */
 298         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 299                 goto give_sigsegv;
 300
 301         /* Set up registers for signal handler */
 302         regs->gprs[15] = (unsigned long) frame;
 303         /* Force default amode and default user address space control. */
 304         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 305                 (PSW_USER_BITS & PSW_MASK_ASC) |
 306                 (regs->psw.mask & ~PSW_MASK_ASC);
 307         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 308
 309         regs->gprs[2] = map_signal(sig);
 310         regs->gprs[3] = (unsigned long) &frame->info;
 311         regs->gprs[4] = (unsigned long) &frame->uc;
 312         regs->gprs[5] = task_thread_info(current)->last_break;
 313         return 0;
 314
 315 give_sigsegv:
 316         force_sigsegv(sig, current);
 317         return -EFAULT;
 318 }
 319
 320 static void handle_signal(unsigned long sig, struct k_sigaction *ka,
 321                          siginfo_t *info, sigset_t *oldset,
 322                          struct pt_regs *regs)
 323 {
 324         int ret;
 325
 326         /* Set up the stack frame */
 327         if (ka->sa.sa_flags & SA_SIGINFO)
 328                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 329         else
 330                 ret = setup_frame(sig, ka, oldset, regs);
 331         if (ret)
 332                 return;
 333         signal_delivered(sig, info, ka, regs,
 334                                  test_thread_flag(TIF_SINGLE_STEP));
 335 }
 336
 337 /*
 338  * Note that 'init' is a special process: it doesn't get signals it doesn't
 339  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 340  * mistake.
 341  *
 342  * Note that we go through the signals twice: once to check the signals that
 343  * the kernel can handle, and then we build all the user-level signal handling
 344  * stack-frames in one go after that.
 345  */
 346 void do_signal(struct pt_regs *regs)
 347 {
 348         siginfo_t info;
 349         int signr;
 350         struct k_sigaction ka;
 351         sigset_t *oldset = sigmask_to_save();
 352
 353         /*
 354          * Get signal to deliver. When running under ptrace, at this point
 355          * the debugger may change all our registers, including the system
 356          * call information.
 357          */
 358         current_thread_info()->system_call =
 359                 test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
 360         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 361
 362         if (signr > 0) {
 363                 /* Whee!  Actually deliver the signal.  */
 364                 if (current_thread_info()->system_call) {
 365                         regs->int_code = current_thread_info()->system_call;
 366                         /* Check for system call restarting. */
 367                         switch (regs->gprs[2]) {
 368                         case -ERESTART_RESTARTBLOCK:
 369                         case -ERESTARTNOHAND:
 370                                 regs->gprs[2] = -EINTR;
 371                                 break;
 372                         case -ERESTARTSYS:
 373                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 374                                         regs->gprs[2] = -EINTR;
 375                                         break;
 376                                 }
 377                         /* fallthrough */
 378                         case -ERESTARTNOINTR:
 379                                 regs->gprs[2] = regs->orig_gpr2;
 380                                 regs->psw.addr =
 381                                         __rewind_psw(regs->psw,
 382                                                      regs->int_code >> 16);
 383                                 break;
 384                         }
 385                 }
 386                 /* No longer in a system call */
 387                 clear_pt_regs_flag(regs, PIF_SYSCALL);
 388
 389                 if (is_compat_task())
 390                         handle_signal32(signr, &ka, &info, oldset, regs);
 391                 else
 392                         handle_signal(signr, &ka, &info, oldset, regs);
 393                 return;
 394         }
 395
 396         /* No handlers present - check for system call restart */
 397         clear_pt_regs_flag(regs, PIF_SYSCALL);
 398         if (current_thread_info()->system_call) {
 399                 regs->int_code = current_thread_info()->system_call;
 400                 switch (regs->gprs[2]) {
 401                 case -ERESTART_RESTARTBLOCK:
 402                         /* Restart with sys_restart_syscall */
 403                         regs->int_code = __NR_restart_syscall;
 404                 /* fallthrough */
 405                 case -ERESTARTNOHAND:
 406                 case -ERESTARTSYS:
 407                 case -ERESTARTNOINTR:
 408                         /* Restart system call with magic TIF bit. */
 409                         regs->gprs[2] = regs->orig_gpr2;
 410                         set_pt_regs_flag(regs, PIF_SYSCALL);
 411                         if (test_thread_flag(TIF_SINGLE_STEP))
 412                                 clear_pt_regs_flag(regs, PIF_PER_TRAP);
 413                         break;
 414                 }
 415         }
 416
 417         /*
 418          * If there's no signal to deliver, we just put the saved sigmask back.
 419          */
 420         restore_saved_sigmask();
 421 }
 422
 423 void do_notify_resume(struct pt_regs *regs)
 424 {
 425         clear_thread_flag(TIF_NOTIFY_RESUME);
 426         tracehook_notify_resume(regs);
 427 }