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