LXR linux/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
  34typedef 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
  43typedef 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. */
  52static 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
  79static 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_thread_flag(TIF_SYSCALL); /* No longer in a system call */
 117        return 0;
 118}
 119
 120SYSCALL_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];
 132badframe:
 133        force_sig(SIGSEGV, current);
 134        return 0;
 135}
 136
 137SYSCALL_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];
 151badframe:
 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 */
 164static inline void __user *
 165get_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
 185static 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
 195static 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
 256give_sigsegv:
 257        force_sigsegv(sig, current);
 258        return -EFAULT;
 259}
 260
 261static 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
 315give_sigsegv:
 316        force_sigsegv(sig, current);
 317        return -EFAULT;
 318}
 319
 320static 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 */
 346void 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_thread_flag(TIF_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_thread_flag(TIF_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_thread_flag(TIF_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_thread_flag(TIF_SYSCALL);
 411                        if (test_thread_flag(TIF_SINGLE_STEP))
 412                                set_thread_flag(TIF_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
 423void do_notify_resume(struct pt_regs *regs)
 424{
 425        clear_thread_flag(TIF_NOTIFY_RESUME);
 426        tracehook_notify_resume(regs);
 427}
 428