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/uprobes.h>
  15 #include <linux/key.h>
  16 #include <linux/context_tracking.h>
  17 #include <asm/hw_breakpoint.h>
  18 #include <asm/uaccess.h>
  19 #include <asm/unistd.h>
  20 #include <asm/debug.h>
  21
  22 #include "signal.h"
  23
  24 /* Log an error when sending an unhandled signal to a process. Controlled
  25  * through debug.exception-trace sysctl.
  26  */
  27
  28 int show_unhandled_signals = 1;
  29
  30 /*
  31  * Allocate space for the signal frame
  32  */
  33 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
  34                            size_t frame_size, int is_32)
  35 {
  36         unsigned long oldsp, newsp;
  37
  38         /* Default to using normal stack */
  39         oldsp = get_clean_sp(regs, is_32);
  40
  41         /* Check for alt stack */
  42         if ((ka->sa.sa_flags & SA_ONSTACK) &&
  43             current->sas_ss_size && !on_sig_stack(oldsp))
  44                 oldsp = (current->sas_ss_sp + current->sas_ss_size);
  45
  46         /* Get aligned frame */
  47         newsp = (oldsp - frame_size) & ~0xFUL;
  48
  49         /* Check access */
  50         if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
  51                 return NULL;
  52
  53         return (void __user *)newsp;
  54 }
  55
  56 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
  57                                   int has_handler)
  58 {
  59         unsigned long ret = regs->gpr[3];
  60         int restart = 1;
  61
  62         /* syscall ? */
  63         if (TRAP(regs) != 0x0C00)
  64                 return;
  65
  66         /* error signalled ? */
  67         if (!(regs->ccr & 0x10000000))
  68                 return;
  69
  70         switch (ret) {
  71         case ERESTART_RESTARTBLOCK:
  72         case ERESTARTNOHAND:
  73                 /* ERESTARTNOHAND means that the syscall should only be
  74                  * restarted if there was no handler for the signal, and since
  75                  * we only get here if there is a handler, we dont restart.
  76                  */
  77                 restart = !has_handler;
  78                 break;
  79         case ERESTARTSYS:
  80                 /* ERESTARTSYS means to restart the syscall if there is no
  81                  * handler or the handler was registered with SA_RESTART
  82                  */
  83                 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
  84                 break;
  85         case ERESTARTNOINTR:
  86                 /* ERESTARTNOINTR means that the syscall should be
  87                  * called again after the signal handler returns.
  88                  */
  89                 break;
  90         default:
  91                 return;
  92         }
  93         if (restart) {
  94                 if (ret == ERESTART_RESTARTBLOCK)
  95                         regs->gpr[0] = __NR_restart_syscall;
  96                 else
  97                         regs->gpr[3] = regs->orig_gpr3;
  98                 regs->nip -= 4;
  99                 regs->result = 0;
 100         } else {
 101                 regs->result = -EINTR;
 102                 regs->gpr[3] = EINTR;
 103                 regs->ccr |= 0x10000000;
 104         }
 105 }
 106
 107 static int do_signal(struct pt_regs *regs)
 108 {
 109         sigset_t *oldset = sigmask_to_save();
 110         siginfo_t info;
 111         int signr;
 112         struct k_sigaction ka;
 113         int ret;
 114         int is32 = is_32bit_task();
 115
 116         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 117
 118         /* Is there any syscall restart business here ? */
 119         check_syscall_restart(regs, &ka, signr > 0);
 120
 121         if (signr <= 0) {
 122                 /* No signal to deliver -- put the saved sigmask back */
 123                 restore_saved_sigmask();
 124                 regs->trap = 0;
 125                 return 0;               /* no signals delivered */
 126         }
 127
 128 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
 129         /*
 130          * Reenable the DABR before delivering the signal to
 131          * user space. The DABR will have been cleared if it
 132          * triggered inside the kernel.
 133          */
 134         if (current->thread.hw_brk.address &&
 135                 current->thread.hw_brk.type)
 136                 set_breakpoint(&current->thread.hw_brk);
 137 #endif
 138         /* Re-enable the breakpoints for the signal stack */
 139         thread_change_pc(current, regs);
 140
 141         if (is32) {
 142                 if (ka.sa.sa_flags & SA_SIGINFO)
 143                         ret = handle_rt_signal32(signr, &ka, &info, oldset,
 144                                         regs);
 145                 else
 146                         ret = handle_signal32(signr, &ka, &info, oldset,
 147                                         regs);
 148         } else {
 149                 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
 150         }
 151
 152         regs->trap = 0;
 153         if (ret) {
 154                 signal_delivered(signr, &info, &ka, regs,
 155                                          test_thread_flag(TIF_SINGLESTEP));
 156         }
 157
 158         return ret;
 159 }
 160
 161 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 162 {
 163         user_exit();
 164
 165         if (thread_info_flags & _TIF_UPROBE)
 166                 uprobe_notify_resume(regs);
 167
 168         if (thread_info_flags & _TIF_SIGPENDING)
 169                 do_signal(regs);
 170
 171         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 172                 clear_thread_flag(TIF_NOTIFY_RESUME);
 173                 tracehook_notify_resume(regs);
 174         }
 175
 176         user_enter();
 177 }