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 <linux/key.h>
  15 #include <asm/hw_breakpoint.h>
  16 #include <asm/uaccess.h>
  17 #include <asm/unistd.h>
  18
  19 #include "signal.h"
  20
  21 /* Log an error when sending an unhandled signal to a process. Controlled
  22  * through debug.exception-trace sysctl.
  23  */
  24
  25 int show_unhandled_signals = 0;
  26
  27 /*
  28  * Allocate space for the signal frame
  29  */
  30 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
  31                            size_t frame_size, int is_32)
  32 {
  33         unsigned long oldsp, newsp;
  34
  35         /* Default to using normal stack */
  36         oldsp = get_clean_sp(regs, is_32);
  37
  38         /* Check for alt stack */
  39         if ((ka->sa.sa_flags & SA_ONSTACK) &&
  40             current->sas_ss_size && !on_sig_stack(oldsp))
  41                 oldsp = (current->sas_ss_sp + current->sas_ss_size);
  42
  43         /* Get aligned frame */
  44         newsp = (oldsp - frame_size) & ~0xFUL;
  45
  46         /* Check access */
  47         if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
  48                 return NULL;
  49
  50         return (void __user *)newsp;
  51 }
  52
  53
  54 /*
  55  * Restore the user process's signal mask
  56  */
  57 void restore_sigmask(sigset_t *set)
  58 {
  59         sigdelsetmask(set, ~_BLOCKABLE);
  60         spin_lock_irq(&current->sighand->siglock);
  61         current->blocked = *set;
  62         recalc_sigpending();
  63         spin_unlock_irq(&current->sighand->siglock);
  64 }
  65
  66 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  67                                   int has_handler)
  68 {
  69         unsigned long ret = regs->gpr[3];
  70         int restart = 1;
  71
  72         /* syscall ? */
  73         if (TRAP(regs) != 0x0C00)
  74                 return;
  75
  76         /* error signalled ? */
  77         if (!(regs->ccr & 0x10000000))
  78                 return;
  79
  80         switch (ret) {
  81         case ERESTART_RESTARTBLOCK:
  82         case ERESTARTNOHAND:
  83                 /* ERESTARTNOHAND means that the syscall should only be
  84                  * restarted if there was no handler for the signal, and since
  85                  * we only get here if there is a handler, we dont restart.
  86                  */
  87                 restart = !has_handler;
  88                 break;
  89         case ERESTARTSYS:
  90                 /* ERESTARTSYS means to restart the syscall if there is no
  91                  * handler or the handler was registered with SA_RESTART
  92                  */
  93                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
  94                 break;
  95         case ERESTARTNOINTR:
  96                 /* ERESTARTNOINTR means that the syscall should be
  97                  * called again after the signal handler returns.
  98                  */
  99                 break;
 100         default:
 101                 return;
 102         }
 103         if (restart) {
 104                 if (ret == ERESTART_RESTARTBLOCK)
 105                         regs->gpr[0] = __NR_restart_syscall;
 106                 else
 107                         regs->gpr[3] = regs->orig_gpr3;
 108                 regs->nip -= 4;
 109                 regs->result = 0;
 110         } else {
 111                 regs->result = -EINTR;
 112                 regs->gpr[3] = EINTR;
 113                 regs->ccr |= 0x10000000;
 114         }
 115 }
 116
 117 static int do_signal(struct pt_regs *regs)
 118 {
 119         sigset_t *oldset;
 120         siginfo_t info;
 121         int signr;
 122         struct k_sigaction ka;
 123         int ret;
 124         int is32 = is_32bit_task();
 125
 126         if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK)
 127                 oldset = &current->saved_sigmask;
 128         else
 129                 oldset = &current->blocked;
 130
 131         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 132
 133         /* Is there any syscall restart business here ? */
 134         check_syscall_restart(regs, &ka, signr > 0);
 135
 136         if (signr <= 0) {
 137                 struct thread_info *ti = current_thread_info();
 138                 /* No signal to deliver -- put the saved sigmask back */
 139                 if (ti->local_flags & _TLF_RESTORE_SIGMASK) {
 140                         ti->local_flags &= ~_TLF_RESTORE_SIGMASK;
 141                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 142                 }
 143                 regs->trap = 0;
 144                 return 0;               /* no signals delivered */
 145         }
 146
 147 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
 148         /*
 149          * Reenable the DABR before delivering the signal to
 150          * user space. The DABR will have been cleared if it
 151          * triggered inside the kernel.
 152          */
 153         if (current->thread.dabr)
 154                 set_dabr(current->thread.dabr);
 155 #endif
 156         /* Re-enable the breakpoints for the signal stack */
 157         thread_change_pc(current, regs);
 158
 159         if (is32) {
 160                 if (ka.sa.sa_flags & SA_SIGINFO)
 161                         ret = handle_rt_signal32(signr, &ka, &info, oldset,
 162                                         regs);
 163                 else
 164                         ret = handle_signal32(signr, &ka, &info, oldset,
 165                                         regs);
 166         } else {
 167                 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
 168         }
 169
 170         regs->trap = 0;
 171         if (ret) {
 172                 spin_lock_irq(&current->sighand->siglock);
 173                 sigorsets(&current->blocked, &current->blocked,
 174                           &ka.sa.sa_mask);
 175                 if (!(ka.sa.sa_flags & SA_NODEFER))
 176                         sigaddset(&current->blocked, signr);
 177                 recalc_sigpending();
 178                 spin_unlock_irq(&current->sighand->siglock);
 179
 180                 /*
 181                  * A signal was successfully delivered; the saved sigmask is in
 182                  * its frame, and we can clear the TLF_RESTORE_SIGMASK flag.
 183                  */
 184                 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;
 185
 186                 /*
 187                  * Let tracing know that we've done the handler setup.
 188                  */
 189                 tracehook_signal_handler(signr, &info, &ka, regs,
 190                                          test_thread_flag(TIF_SINGLESTEP));
 191         }
 192
 193         return ret;
 194 }
 195
 196 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 197 {
 198         if (thread_info_flags & _TIF_SIGPENDING)
 199                 do_signal(regs);
 200
 201         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 202                 clear_thread_flag(TIF_NOTIFY_RESUME);
 203                 tracehook_notify_resume(regs);
 204                 if (current->replacement_session_keyring)
 205                         key_replace_session_keyring();
 206         }
 207 }
 208
 209 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 210                 unsigned long r5, unsigned long r6, unsigned long r7,
 211                 unsigned long r8, struct pt_regs *regs)
 212 {
 213         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 214 }