arch/powerpc/kernel/signal.c

   1 /*
   2  * Common signal handling code for both 32 and 64 bits
   3  *
   4  *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
   5  *    Extracted from signal_32.c and signal_64.c
   6  *
   7  * This file is subject to the terms and conditions of the GNU General
   8  * Public License.  See the file README.legal in the main directory of
   9  * this archive for more details.
  10  */
  11
  12 #include <linux/ptrace.h>
  13 #include <linux/signal.h>
  14 #include <asm/uaccess.h>
  15 #include <asm/unistd.h>
  16
  17 #include "signal.h"
  18
  19 /*
  20  * Allocate space for the signal frame
  21  */
  22 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
  23                            size_t frame_size)
  24 {
  25         unsigned long oldsp, newsp;
  26
  27         /* Default to using normal stack */
  28         oldsp = regs->gpr[1];
  29
  30         /* Check for alt stack */
  31         if ((ka->sa.sa_flags & SA_ONSTACK) &&
  32             current->sas_ss_size && !on_sig_stack(oldsp))
  33                 oldsp = (current->sas_ss_sp + current->sas_ss_size);
  34
  35         /* Get aligned frame */
  36         newsp = (oldsp - frame_size) & ~0xFUL;
  37
  38         /* Check access */
  39         if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
  40                 return NULL;
  41
  42         return (void __user *)newsp;
  43 }
  44
  45
  46 /*
  47  * Restore the user process's signal mask
  48  */
  49 void restore_sigmask(sigset_t *set)
  50 {
  51         sigdelsetmask(set, ~_BLOCKABLE);
  52         spin_lock_irq(&current->sighand->siglock);
  53         current->blocked = *set;
  54         recalc_sigpending();
  55         spin_unlock_irq(&current->sighand->siglock);
  56 }
  57
  58 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  59                                   int has_handler)
  60 {
  61         unsigned long ret = regs->gpr[3];
  62         int restart = 1;
  63
  64         /* syscall ? */
  65         if (TRAP(regs) != 0x0C00)
  66                 return;
  67
  68         /* error signalled ? */
  69         if (!(regs->ccr & 0x10000000))
  70                 return;
  71
  72         switch (ret) {
  73         case ERESTART_RESTARTBLOCK:
  74         case ERESTARTNOHAND:
  75                 /* ERESTARTNOHAND means that the syscall should only be
  76                  * restarted if there was no handler for the signal, and since
  77                  * we only get here if there is a handler, we dont restart.
  78                  */
  79                 restart = !has_handler;
  80                 break;
  81         case ERESTARTSYS:
  82                 /* ERESTARTSYS means to restart the syscall if there is no
  83                  * handler or the handler was registered with SA_RESTART
  84                  */
  85                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
  86                 break;
  87         case ERESTARTNOINTR:
  88                 /* ERESTARTNOINTR means that the syscall should be
  89                  * called again after the signal handler returns.
  90                  */
  91                 break;
  92         default:
  93                 return;
  94         }
  95         if (restart) {
  96                 if (ret == ERESTART_RESTARTBLOCK)
  97                         regs->gpr[0] = __NR_restart_syscall;
  98                 else
  99                         regs->gpr[3] = regs->orig_gpr3;
 100                 regs->nip -= 4;
 101                 regs->result = 0;
 102         } else {
 103                 regs->result = -EINTR;
 104                 regs->gpr[3] = EINTR;
 105                 regs->ccr |= 0x10000000;
 106         }
 107 }
 108
 109 int do_signal(sigset_t *oldset, struct pt_regs *regs)
 110 {
 111         siginfo_t info;
 112         int signr;
 113         struct k_sigaction ka;
 114         int ret;
 115         int is32 = is_32bit_task();
 116
 117         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 118                 oldset = &current->saved_sigmask;
 119         else if (!oldset)
 120                 oldset = &current->blocked;
 121
 122         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 123
 124         /* Is there any syscall restart business here ? */
 125         check_syscall_restart(regs, &ka, signr > 0);
 126
 127         if (signr <= 0) {
 128                 /* No signal to deliver -- put the saved sigmask back */
 129                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 130                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 131                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 132                 }
 133                 return 0;               /* no signals delivered */
 134         }
 135
 136         /*
 137          * Reenable the DABR before delivering the signal to
 138          * user space. The DABR will have been cleared if it
 139          * triggered inside the kernel.
 140          */
 141         if (current->thread.dabr)
 142                 set_dabr(current->thread.dabr);
 143
 144         if (is32) {
 145                 if (ka.sa.sa_flags & SA_SIGINFO)
 146                         ret = handle_rt_signal32(signr, &ka, &info, oldset,
 147                                         regs);
 148                 else
 149                         ret = handle_signal32(signr, &ka, &info, oldset,
 150                                         regs);
 151         } else {
 152                 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
 153         }
 154
 155         if (ret) {
 156                 spin_lock_irq(&current->sighand->siglock);
 157                 sigorsets(&current->blocked, &current->blocked,
 158                           &ka.sa.sa_mask);
 159                 if (!(ka.sa.sa_flags & SA_NODEFER))
 160                         sigaddset(&current->blocked, signr);
 161                 recalc_sigpending();
 162                 spin_unlock_irq(&current->sighand->siglock);
 163
 164                 /*
 165                  * A signal was successfully delivered; the saved sigmask is in
 166                  * its frame, and we can clear the TIF_RESTORE_SIGMASK flag.
 167                  */
 168                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 169                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 170         }
 171
 172         return ret;
 173 }
 174
 175 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 176                 unsigned long r5, unsigned long r6, unsigned long r7,
 177                 unsigned long r8, struct pt_regs *regs)
 178 {
 179         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 180 }