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 #include <asm/debug.h>
  19
  20 #include "signal.h"
  21
  22 /* Log an error when sending an unhandled signal to a process. Controlled
  23  * through debug.exception-trace sysctl.
  24  */
  25
  26 int show_unhandled_signals = 0;
  27
  28 /*
  29  * Allocate space for the signal frame
  30  */
  31 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
  32                            size_t frame_size, int is_32)
  33 {
  34         unsigned long oldsp, newsp;
  35
  36         /* Default to using normal stack */
  37         oldsp = get_clean_sp(regs, is_32);
  38
  39         /* Check for alt stack */
  40         if ((ka->sa.sa_flags & SA_ONSTACK) &&
  41             current->sas_ss_size && !on_sig_stack(oldsp))
  42                 oldsp = (current->sas_ss_sp + current->sas_ss_size);
  43
  44         /* Get aligned frame */
  45         newsp = (oldsp - frame_size) & ~0xFUL;
  46
  47         /* Check access */
  48         if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
  49                 return NULL;
  50
  51         return (void __user *)newsp;
  52 }
  53
  54
  55 /*
  56  * Restore the user process's signal mask
  57  */
  58 void restore_sigmask(sigset_t *set)
  59 {
  60         sigdelsetmask(set, ~_BLOCKABLE);
  61         set_current_blocked(set);
  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(struct pt_regs *regs)
 116 {
 117         sigset_t *oldset;
 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
 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                 regs->trap = 0;
 142                 return 0;               /* no signals delivered */
 143         }
 144
 145 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
 146         /*
 147          * Reenable the DABR before delivering the signal to
 148          * user space. The DABR will have been cleared if it
 149          * triggered inside the kernel.
 150          */
 151         if (current->thread.dabr)
 152                 set_dabr(current->thread.dabr);
 153 #endif
 154         /* Re-enable the breakpoints for the signal stack */
 155         thread_change_pc(current, regs);
 156
 157         if (is32) {
 158                 if (ka.sa.sa_flags & SA_SIGINFO)
 159                         ret = handle_rt_signal32(signr, &ka, &info, oldset,
 160                                         regs);
 161                 else
 162                         ret = handle_signal32(signr, &ka, &info, oldset,
 163                                         regs);
 164         } else {
 165                 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
 166         }
 167
 168         regs->trap = 0;
 169         if (ret) {
 170                 block_sigmask(&ka, signr);
 171
 172                 /*
 173                  * A signal was successfully delivered; the saved sigmask is in
 174                  * its frame, and we can clear the TLF_RESTORE_SIGMASK flag.
 175                  */
 176                 current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;
 177
 178                 /*
 179                  * Let tracing know that we've done the handler setup.
 180                  */
 181                 tracehook_signal_handler(signr, &info, &ka, regs,
 182                                          test_thread_flag(TIF_SINGLESTEP));
 183         }
 184
 185         return ret;
 186 }
 187
 188 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 189 {
 190         if (thread_info_flags & _TIF_SIGPENDING)
 191                 do_signal(regs);
 192
 193         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 194                 clear_thread_flag(TIF_NOTIFY_RESUME);
 195                 tracehook_notify_resume(regs);
 196         }
 197 }
 198
 199 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 200                 unsigned long r5, unsigned long r6, unsigned long r7,
 201                 unsigned long r8, struct pt_regs *regs)
 202 {
 203         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 204 }