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/unistd.h>
  15
  16 #include "signal.h"
  17
  18
  19 #ifdef CONFIG_PPC64
  20 static inline int is_32bit_task(void)
  21 {
  22         return test_thread_flag(TIF_32BIT);
  23 }
  24 #else
  25 static inline int is_32bit_task(void)
  26 {
  27         return 1;
  28 }
  29 #endif
  30
  31
  32 /*
  33  * Restore the user process's signal mask
  34  */
  35 void restore_sigmask(sigset_t *set)
  36 {
  37         sigdelsetmask(set, ~_BLOCKABLE);
  38         spin_lock_irq(&current->sighand->siglock);
  39         current->blocked = *set;
  40         recalc_sigpending();
  41         spin_unlock_irq(&current->sighand->siglock);
  42 }
  43
  44 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  45                                   int has_handler)
  46 {
  47         unsigned long ret = regs->gpr[3];
  48         int restart = 1;
  49
  50         /* syscall ? */
  51         if (TRAP(regs) != 0x0C00)
  52                 return;
  53
  54         /* error signalled ? */
  55         if (!(regs->ccr & 0x10000000))
  56                 return;
  57
  58         switch (ret) {
  59         case ERESTART_RESTARTBLOCK:
  60         case ERESTARTNOHAND:
  61                 /* ERESTARTNOHAND means that the syscall should only be
  62                  * restarted if there was no handler for the signal, and since
  63                  * we only get here if there is a handler, we dont restart.
  64                  */
  65                 restart = !has_handler;
  66                 break;
  67         case ERESTARTSYS:
  68                 /* ERESTARTSYS means to restart the syscall if there is no
  69                  * handler or the handler was registered with SA_RESTART
  70                  */
  71                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
  72                 break;
  73         case ERESTARTNOINTR:
  74                 /* ERESTARTNOINTR means that the syscall should be
  75                  * called again after the signal handler returns.
  76                  */
  77                 break;
  78         default:
  79                 return;
  80         }
  81         if (restart) {
  82                 if (ret == ERESTART_RESTARTBLOCK)
  83                         regs->gpr[0] = __NR_restart_syscall;
  84                 else
  85                         regs->gpr[3] = regs->orig_gpr3;
  86                 regs->nip -= 4;
  87                 regs->result = 0;
  88         } else {
  89                 regs->result = -EINTR;
  90                 regs->gpr[3] = EINTR;
  91                 regs->ccr |= 0x10000000;
  92         }
  93 }
  94
  95 int do_signal(sigset_t *oldset, struct pt_regs *regs)
  96 {
  97         siginfo_t info;
  98         int signr;
  99         struct k_sigaction ka;
 100         int ret;
 101         int is32 = is_32bit_task();
 102
 103         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 104                 oldset = &current->saved_sigmask;
 105         else if (!oldset)
 106                 oldset = &current->blocked;
 107
 108         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 109
 110         /* Is there any syscall restart business here ? */
 111         check_syscall_restart(regs, &ka, signr > 0);
 112
 113         if (signr <= 0) {
 114                 /* No signal to deliver -- put the saved sigmask back */
 115                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 116                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 117                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 118                 }
 119                 return 0;               /* no signals delivered */
 120         }
 121
 122 #ifdef CONFIG_PPC64
 123         /*
 124          * Reenable the DABR before delivering the signal to
 125          * user space. The DABR will have been cleared if it
 126          * triggered inside the kernel.
 127          */
 128         if (current->thread.dabr)
 129                 set_dabr(current->thread.dabr);
 130 #endif
 131
 132         if (is32) {
 133                 unsigned int newsp;
 134
 135                 if ((ka.sa.sa_flags & SA_ONSTACK) &&
 136                     current->sas_ss_size && !on_sig_stack(regs->gpr[1]))
 137                         newsp = current->sas_ss_sp + current->sas_ss_size;
 138                 else
 139                         newsp = regs->gpr[1];
 140
 141                 if (ka.sa.sa_flags & SA_SIGINFO)
 142                         ret = handle_rt_signal32(signr, &ka, &info, oldset,
 143                                         regs, newsp);
 144                 else
 145                         ret = handle_signal32(signr, &ka, &info, oldset,
 146                                         regs, newsp);
 147 #ifdef CONFIG_PPC64
 148         } else {
 149                 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
 150 #endif
 151         }
 152
 153         if (ret) {
 154                 spin_lock_irq(&current->sighand->siglock);
 155                 sigorsets(&current->blocked, &current->blocked,
 156                           &ka.sa.sa_mask);
 157                 if (!(ka.sa.sa_flags & SA_NODEFER))
 158                         sigaddset(&current->blocked, signr);
 159                 recalc_sigpending();
 160                 spin_unlock_irq(&current->sighand->siglock);
 161
 162                 /*
 163                  * A signal was successfully delivered; the saved sigmask is in
 164                  * its frame, and we can clear the TIF_RESTORE_SIGMASK flag.
 165                  */
 166                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 167                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 168         }
 169
 170         return ret;
 171 }
 172
 173 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 174                 unsigned long r5, unsigned long r6, unsigned long r7,
 175                 unsigned long r8, struct pt_regs *regs)
 176 {
 177         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 178 }