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         set_current_blocked(set);
  61 }
  62
  63 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  64                                   int has_handler)
  65 {
  66         unsigned long ret = regs->gpr[3];
  67         int restart = 1;
  68
  69         /* syscall ? */
  70         if (TRAP(regs) != 0x0C00)
  71                 return;
  72
  73         /* error signalled ? */
  74         if (!(regs->ccr & 0x10000000))
  75                 return;
  76
  77         switch (ret) {
  78         case ERESTART_RESTARTBLOCK:
  79         case ERESTARTNOHAND:
  80                 /* ERESTARTNOHAND means that the syscall should only be
  81                  * restarted if there was no handler for the signal, and since
  82                  * we only get here if there is a handler, we dont restart.
  83                  */
  84                 restart = !has_handler;
  85                 break;
  86         case ERESTARTSYS:
  87                 /* ERESTARTSYS means to restart the syscall if there is no
  88                  * handler or the handler was registered with SA_RESTART
  89                  */
  90                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
  91                 break;
  92         case ERESTARTNOINTR:
  93                 /* ERESTARTNOINTR means that the syscall should be
  94                  * called again after the signal handler returns.
  95                  */
  96                 break;
  97         default:
  98                 return;
  99         }
 100         if (restart) {
 101                 if (ret == ERESTART_RESTARTBLOCK)
 102                         regs->gpr[0] = __NR_restart_syscall;
 103                 else
 104                         regs->gpr[3] = regs->orig_gpr3;
 105                 regs->nip -= 4;
 106                 regs->result = 0;
 107         } else {
 108                 regs->result = -EINTR;
 109                 regs->gpr[3] = EINTR;
 110                 regs->ccr |= 0x10000000;
 111         }
 112 }
 113
 114 static int do_signal(struct pt_regs *regs)
 115 {
 116         sigset_t *oldset;
 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
 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                 regs->trap = 0;
 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         regs->trap = 0;
 168         if (ret) {
 169                 block_sigmask(&ka, signr);
 170
 171                 /*
 172                  * A signal was successfully delivered; the saved sigmask is in
 173                  * its frame, and we can clear the TLF_RESTORE_SIGMASK flag.
 174                  */
 175                 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;
 176
 177                 /*
 178                  * Let tracing know that we've done the handler setup.
 179                  */
 180                 tracehook_signal_handler(signr, &info, &ka, regs,
 181                                          test_thread_flag(TIF_SINGLESTEP));
 182         }
 183
 184         return ret;
 185 }
 186
 187 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 188 {
 189         if (thread_info_flags & _TIF_SIGPENDING)
 190                 do_signal(regs);
 191
 192         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 193                 clear_thread_flag(TIF_NOTIFY_RESUME);
 194                 tracehook_notify_resume(regs);
 195                 if (current->replacement_session_keyring)
 196                         key_replace_session_keyring();
 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 }