arch/um/kernel/signal_kern.c

   1 /*
   2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/config.h"
   7 #include "linux/stddef.h"
   8 #include "linux/sys.h"
   9 #include "linux/sched.h"
  10 #include "linux/wait.h"
  11 #include "linux/kernel.h"
  12 #include "linux/smp_lock.h"
  13 #include "linux/module.h"
  14 #include "linux/slab.h"
  15 #include "linux/tty.h"
  16 #include "linux/binfmts.h"
  17 #include "linux/ptrace.h"
  18 #include "asm/signal.h"
  19 #include "asm/uaccess.h"
  20 #include "asm/unistd.h"
  21 #include "user_util.h"
  22 #include "asm/ucontext.h"
  23 #include "kern_util.h"
  24 #include "signal_kern.h"
  25 #include "signal_user.h"
  26 #include "kern.h"
  27 #include "frame_kern.h"
  28 #include "sigcontext.h"
  29 #include "mode.h"
  30
  31 EXPORT_SYMBOL(block_signals);
  32 EXPORT_SYMBOL(unblock_signals);
  33
  34 #define _S(nr) (1<<((nr)-1))
  35
  36 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  37
  38 /*
  39  * OK, we're invoking a handler
  40  */
  41 static int handle_signal(struct pt_regs *regs, unsigned long signr,
  42                          struct k_sigaction *ka, siginfo_t *info,
  43                          sigset_t *oldset, int error)
  44 {
  45         __sighandler_t handler;
  46         void (*restorer)(void);
  47         unsigned long sp;
  48         sigset_t save;
  49         int err, ret;
  50
  51         ret = 0;
  52         /* Always make any pending restarted system calls return -EINTR */
  53         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  54         switch(error){
  55         case -ERESTART_RESTARTBLOCK:
  56         case -ERESTARTNOHAND:
  57                 ret = -EINTR;
  58                 break;
  59
  60         case -ERESTARTSYS:
  61                 if (!(ka->sa.sa_flags & SA_RESTART)) {
  62                         ret = -EINTR;
  63                         break;
  64                 }
  65                 /* fallthrough */
  66         case -ERESTARTNOINTR:
  67                 PT_REGS_RESTART_SYSCALL(regs);
  68                 PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  69
  70                 /* This is because of the UM_SET_SYSCALL_RETURN and the fact
  71                  * that on i386 the system call number and return value are
  72                  * in the same register.  When the system call restarts, %eax
  73                  * had better have the system call number in it.  Since the
  74                  * return value doesn't matter (except that it shouldn't be
  75                  * -ERESTART*), we'll stick the system call number there.
  76                  */
  77                 ret = PT_REGS_SYSCALL_NR(regs);
  78                 break;
  79         }
  80
  81         handler = ka->sa.sa_handler;
  82         save = *oldset;
  83
  84         if (ka->sa.sa_flags & SA_ONESHOT)
  85                 ka->sa.sa_handler = SIG_DFL;
  86
  87         if (!(ka->sa.sa_flags & SA_NODEFER)) {
  88                 spin_lock_irq(&current->sighand->siglock);
  89                 sigorsets(&current->blocked, &current->blocked,
  90                           &ka->sa.sa_mask);
  91                 sigaddset(&current->blocked, signr);
  92                 recalc_sigpending();
  93                 spin_unlock_irq(&current->sighand->siglock);
  94         }
  95
  96         sp = PT_REGS_SP(regs);
  97
  98         if((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  99                 sp = current->sas_ss_sp + current->sas_ss_size;
 100
 101         if(error != 0) PT_REGS_SET_SYSCALL_RETURN(regs, ret);
 102
 103         if (ka->sa.sa_flags & SA_RESTORER) restorer = ka->sa.sa_restorer;
 104         else restorer = NULL;
 105
 106         if(ka->sa.sa_flags & SA_SIGINFO)
 107                 err = setup_signal_stack_si(sp, signr, (unsigned long) handler,
 108                                             restorer, regs, info, &save);
 109         else
 110                 err = setup_signal_stack_sc(sp, signr, (unsigned long) handler,
 111                                             restorer, regs, &save);
 112         if(err) goto segv;
 113
 114         return(0);
 115  segv:
 116         force_sigsegv(signr, current);
 117         return(1);
 118 }
 119
 120 static int kern_do_signal(struct pt_regs *regs, sigset_t *oldset, int error)
 121 {
 122         struct k_sigaction ka_copy;
 123         siginfo_t info;
 124         int err, sig;
 125
 126         if (!oldset)
 127                 oldset = &current->blocked;
 128
 129         sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL);
 130         if(sig == 0)
 131                 return(0);
 132
 133         /* Whee!  Actually deliver the signal.  */
 134         err = handle_signal(regs, sig, &ka_copy, &info, oldset, error);
 135         if(!err)
 136                 return(1);
 137
 138         /* Did we come from a system call? */
 139         if(PT_REGS_SYSCALL_NR(regs) >= 0){
 140                 /* Restart the system call - no handlers present */
 141                 if(PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOHAND ||
 142                    PT_REGS_SYSCALL_RET(regs) == -ERESTARTSYS ||
 143                    PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOINTR){
 144                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 145                         PT_REGS_RESTART_SYSCALL(regs);
 146                 }
 147                 else if(PT_REGS_SYSCALL_RET(regs) == -ERESTART_RESTARTBLOCK){
 148                         PT_REGS_SYSCALL_RET(regs) = __NR_restart_syscall;
 149                         PT_REGS_RESTART_SYSCALL(regs);
 150                 }
 151         }
 152
 153         /* This closes a way to execute a system call on the host.  If
 154          * you set a breakpoint on a system call instruction and singlestep
 155          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 156          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 157          * on the host.  The tracing thread will check this flag and
 158          * PTRACE_SYSCALL if necessary.
 159          */
 160         if((current->ptrace & PT_DTRACE) &&
 161            is_syscall(PT_REGS_IP(&current->thread.regs)))
 162                 (void) CHOOSE_MODE(current->thread.mode.tt.singlestep_syscall = 1, 0);
 163         return(0);
 164 }
 165
 166 int do_signal(int error)
 167 {
 168         return(kern_do_signal(&current->thread.regs, NULL, error));
 169 }
 170
 171 /*
 172  * Atomically swap in the new signal mask, and wait for a signal.
 173  */
 174 int sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 175 {
 176         sigset_t saveset;
 177
 178         mask &= _BLOCKABLE;
 179         spin_lock_irq(&current->sighand->siglock);
 180         saveset = current->blocked;
 181         siginitset(&current->blocked, mask);
 182         recalc_sigpending();
 183         spin_unlock_irq(&current->sighand->siglock);
 184
 185         while (1) {
 186                 current->state = TASK_INTERRUPTIBLE;
 187                 schedule();
 188                 if(kern_do_signal(&current->thread.regs, &saveset, -EINTR))
 189                         return(-EINTR);
 190         }
 191 }
 192
 193 int sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
 194 {
 195         sigset_t saveset, newset;
 196
 197         /* XXX: Don't preclude handling different sized sigset_t's.  */
 198         if (sigsetsize != sizeof(sigset_t))
 199                 return -EINVAL;
 200
 201         if (copy_from_user(&newset, unewset, sizeof(newset)))
 202                 return -EFAULT;
 203         sigdelsetmask(&newset, ~_BLOCKABLE);
 204
 205         spin_lock_irq(&current->sighand->siglock);
 206         saveset = current->blocked;
 207         current->blocked = newset;
 208         recalc_sigpending();
 209         spin_unlock_irq(&current->sighand->siglock);
 210
 211         while (1) {
 212                 current->state = TASK_INTERRUPTIBLE;
 213                 schedule();
 214                 if (kern_do_signal(&current->thread.regs, &saveset, -EINTR))
 215                         return(-EINTR);
 216         }
 217 }
 218
 219 int sys_sigaction(int sig, const struct old_sigaction __user *act,
 220                          struct old_sigaction __user *oact)
 221 {
 222         struct k_sigaction new_ka, old_ka;
 223         int ret;
 224
 225         if (act) {
 226                 old_sigset_t mask;
 227                 if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
 228                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 229                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 230                         return -EFAULT;
 231                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 232                 __get_user(mask, &act->sa_mask);
 233                 siginitset(&new_ka.sa.sa_mask, mask);
 234         }
 235
 236         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 237
 238         if (!ret && oact) {
 239                 if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
 240                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 241                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 242                         return -EFAULT;
 243                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 244                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 245         }
 246
 247         return ret;
 248 }
 249
 250 int sys_sigaltstack(const stack_t *uss, stack_t *uoss)
 251 {
 252         return(do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs)));
 253 }
 254
 255 extern int userspace_pid[];
 256
 257 static int copy_sc_from_user(struct pt_regs *to, void *from,
 258                              struct arch_frame_data *arch)
 259 {
 260         int ret;
 261
 262         ret = CHOOSE_MODE(copy_sc_from_user_tt(UPT_SC(&to->regs), from, arch),
 263                           copy_sc_from_user_skas(userspace_pid[0],
 264                                                  &to->regs, from));
 265         return(ret);
 266 }
 267
 268 int sys_sigreturn(struct pt_regs regs)
 269 {
 270         void __user *sc = sp_to_sc(PT_REGS_SP(&current->thread.regs));
 271         void __user *mask = sp_to_mask(PT_REGS_SP(&current->thread.regs));
 272         int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 273
 274         spin_lock_irq(&current->sighand->siglock);
 275         copy_from_user(&current->blocked.sig[0], sc_sigmask(sc),
 276                        sizeof(current->blocked.sig[0]));
 277         copy_from_user(&current->blocked.sig[1], mask, sig_size);
 278         sigdelsetmask(&current->blocked, ~_BLOCKABLE);
 279         recalc_sigpending();
 280         spin_unlock_irq(&current->sighand->siglock);
 281         copy_sc_from_user(&current->thread.regs, sc,
 282                           &signal_frame_sc.common.arch);
 283         return(PT_REGS_SYSCALL_RET(&current->thread.regs));
 284 }
 285
 286 int sys_rt_sigreturn(struct pt_regs regs)
 287 {
 288         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 289         struct ucontext __user *uc = sp_to_uc(sp);
 290         int sig_size = _NSIG_WORDS * sizeof(unsigned long);
 291
 292         spin_lock_irq(&current->sighand->siglock);
 293         copy_from_user(&current->blocked, &uc->uc_sigmask, sig_size);
 294         sigdelsetmask(&current->blocked, ~_BLOCKABLE);
 295         recalc_sigpending();
 296         spin_unlock_irq(&current->sighand->siglock);
 297         copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext,
 298                           &signal_frame_si.common.arch);
 299         return(PT_REGS_SYSCALL_RET(&current->thread.regs));
 300 }
 301
 302 /*
 303  * Overrides for Emacs so that we follow Linus's tabbing style.
 304  * Emacs will notice this stuff at the end of the file and automatically
 305  * adjust the settings for this buffer only.  This must remain at the end
 306  * of the file.
 307  * ---------------------------------------------------------------------------
 308  * Local variables:
 309  * c-file-style: "linux"
 310  * End:
 311  */