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/tracehook.h>
  13 #include <linux/signal.h>
  14 #include <asm/hw_breakpoint.h>
  15 #include <asm/uaccess.h>
  16 #include <asm/unistd.h>
  17
  18 #include "signal.h"
  19
  20 /* Log an error when sending an unhandled signal to a process. Controlled
  21  * through debug.exception-trace sysctl.
  22  */
  23
  24 int show_unhandled_signals = 0;
  25
  26 /*
  27  * Allocate space for the signal frame
  28  */
  29 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
  30                            size_t frame_size, int is_32)
  31 {
  32         unsigned long oldsp, newsp;
  33
  34         /* Default to using normal stack */
  35         oldsp = get_clean_sp(regs, is_32);
  36
  37         /* Check for alt stack */
  38         if ((ka->sa.sa_flags & SA_ONSTACK) &&
  39             current->sas_ss_size && !on_sig_stack(oldsp))
  40                 oldsp = (current->sas_ss_sp + current->sas_ss_size);
  41
  42         /* Get aligned frame */
  43         newsp = (oldsp - frame_size) & ~0xFUL;
  44
  45         /* Check access */
  46         if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
  47                 return NULL;
  48
  49         return (void __user *)newsp;
  50 }
  51
  52
  53 /*
  54  * Restore the user process's signal mask
  55  */
  56 void restore_sigmask(sigset_t *set)
  57 {
  58         sigdelsetmask(set, ~_BLOCKABLE);
  59         spin_lock_irq(&current->sighand->siglock);
  60         current->blocked = *set;
  61         recalc_sigpending();
  62         spin_unlock_irq(&current->sighand->siglock);
  63 }
  64
  65 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  66                                   int has_handler)
  67 {
  68         unsigned long ret = regs->gpr[3];
  69         int restart = 1;
  70
  71         /* syscall ? */
  72         if (TRAP(regs) != 0x0C00)
  73                 return;
  74
  75         /* error signalled ? */
  76         if (!(regs->ccr & 0x10000000))
  77                 return;
  78
  79         switch (ret) {
  80         case ERESTART_RESTARTBLOCK:
  81         case ERESTARTNOHAND:
  82                 /* ERESTARTNOHAND means that the syscall should only be
  83                  * restarted if there was no handler for the signal, and since
  84                  * we only get here if there is a handler, we dont restart.
  85                  */
  86                 restart = !has_handler;
  87                 break;
  88         case ERESTARTSYS:
  89                 /* ERESTARTSYS means to restart the syscall if there is no
  90                  * handler or the handler was registered with SA_RESTART
  91                  */
  92                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
  93                 break;
  94         case ERESTARTNOINTR:
  95                 /* ERESTARTNOINTR means that the syscall should be
  96                  * called again after the signal handler returns.
  97                  */
  98                 break;
  99         default:
 100                 return;
 101         }
 102         if (restart) {
 103                 if (ret == ERESTART_RESTARTBLOCK)
 104                         regs->gpr[0] = __NR_restart_syscall;
 105                 else
 106                         regs->gpr[3] = regs->orig_gpr3;
 107                 regs->nip -= 4;
 108                 regs->result = 0;
 109         } else {
 110                 regs->result = -EINTR;
 111                 regs->gpr[3] = EINTR;
 112                 regs->ccr |= 0x10000000;
 113         }
 114 }
 115
 116 static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
 117 {
 118         siginfo_t info;
 119         int signr;
 120         struct k_sigaction ka;
 121         int ret;
 122         int is32 = is_32bit_task();
 123
 124         if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK)
 125                 oldset = &current->saved_sigmask;
 126         else if (!oldset)
 127                 oldset = &current->blocked;
 128
 129         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 130
 131         /* Is there any syscall restart business here ? */
 132         check_syscall_restart(regs, &ka, signr > 0);
 133
 134         if (signr <= 0) {
 135                 struct thread_info *ti = current_thread_info();
 136                 /* No signal to deliver -- put the saved sigmask back */
 137                 if (ti->local_flags & _TLF_RESTORE_SIGMASK) {
 138                         ti->local_flags &= ~_TLF_RESTORE_SIGMASK;
 139                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 140                 }
 141                 return 0;               /* no signals delivered */
 142         }
 143
 144 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
 145         /*
 146          * Reenable the DABR before delivering the signal to
 147          * user space. The DABR will have been cleared if it
 148          * triggered inside the kernel.
 149          */
 150         if (current->thread.dabr)
 151                 set_dabr(current->thread.dabr);
 152 #endif
 153         /* Re-enable the breakpoints for the signal stack */
 154         thread_change_pc(current, regs);
 155
 156         if (is32) {
 157                 if (ka.sa.sa_flags & SA_SIGINFO)
 158                         ret = handle_rt_signal32(signr, &ka, &info, oldset,
 159                                         regs);
 160                 else
 161                         ret = handle_signal32(signr, &ka, &info, oldset,
 162                                         regs);
 163         } else {
 164                 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
 165         }
 166
 167         if (ret) {
 168                 spin_lock_irq(&current->sighand->siglock);
 169                 sigorsets(&current->blocked, &current->blocked,
 170                           &ka.sa.sa_mask);
 171                 if (!(ka.sa.sa_flags & SA_NODEFER))
 172                         sigaddset(&current->blocked, signr);
 173                 recalc_sigpending();
 174                 spin_unlock_irq(&current->sighand->siglock);
 175
 176                 /*
 177                  * A signal was successfully delivered; the saved sigmask is in
 178                  * its frame, and we can clear the TLF_RESTORE_SIGMASK flag.
 179                  */
 180                 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;
 181
 182                 /*
 183                  * Let tracing know that we've done the handler setup.
 184                  */
 185                 tracehook_signal_handler(signr, &info, &ka, regs,
 186                                          test_thread_flag(TIF_SINGLESTEP));
 187         }
 188
 189         return ret;
 190 }
 191
 192 void do_signal(struct pt_regs *regs, unsigned long thread_info_flags)
 193 {
 194         if (thread_info_flags & _TIF_SIGPENDING)
 195                 do_signal_pending(NULL, regs);
 196
 197         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 198                 clear_thread_flag(TIF_NOTIFY_RESUME);
 199                 tracehook_notify_resume(regs);
 200         }
 201 }
 202
 203 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 204                 unsigned long r5, unsigned long r6, unsigned long r7,
 205                 unsigned long r8, struct pt_regs *regs)
 206 {
 207         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 208 }