arch/um/os-Linux/signal.c

   1 /*
   2  * Copyright (C) 2004 PathScale, Inc
   3  * Licensed under the GPL
   4  */
   5
   6 #include <signal.h>
   7 #include <stdio.h>
   8 #include <unistd.h>
   9 #include <stdlib.h>
  10 #include <errno.h>
  11 #include <stdarg.h>
  12 #include <string.h>
  13 #include <sys/mman.h>
  14 #include "user_util.h"
  15 #include "user.h"
  16 #include "signal_kern.h"
  17 #include "sysdep/sigcontext.h"
  18 #include "sysdep/signal.h"
  19 #include "sigcontext.h"
  20 #include "mode.h"
  21 #include "os.h"
  22
  23 /* These are the asynchronous signals.  SIGVTALRM and SIGARLM are handled
  24  * together under SIGVTALRM_BIT.  SIGPROF is excluded because we want to
  25  * be able to profile all of UML, not just the non-critical sections.  If
  26  * profiling is not thread-safe, then that is not my problem.  We can disable
  27  * profiling when SMP is enabled in that case.
  28  */
  29 #define SIGIO_BIT 0
  30 #define SIGIO_MASK (1 << SIGIO_BIT)
  31
  32 #define SIGVTALRM_BIT 1
  33 #define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
  34
  35 #define SIGALRM_BIT 2
  36 #define SIGALRM_MASK (1 << SIGALRM_BIT)
  37
  38 static int signals_enabled = 1;
  39 static int pending = 0;
  40
  41 void sig_handler(ARCH_SIGHDLR_PARAM)
  42 {
  43         struct sigcontext *sc;
  44         int enabled;
  45
  46         /* Must be the first thing that this handler does - x86_64 stores
  47          * the sigcontext in %rdx, and we need to save it before it has a
  48          * chance to get trashed.
  49          */
  50
  51         ARCH_GET_SIGCONTEXT(sc, sig);
  52
  53         enabled = signals_enabled;
  54         if(!enabled && (sig == SIGIO)){
  55                 pending |= SIGIO_MASK;
  56                 return;
  57         }
  58
  59         block_signals();
  60
  61         CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
  62                          sig, sc);
  63
  64         set_signals(enabled);
  65 }
  66
  67 extern int timer_irq_inited;
  68
  69 static void real_alarm_handler(int sig, struct sigcontext *sc)
  70 {
  71         if(!timer_irq_inited){
  72                 signals_enabled = 1;
  73                 return;
  74         }
  75
  76         if(sig == SIGALRM)
  77                 switch_timers(0);
  78
  79         CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
  80                          sig, sc);
  81
  82         if(sig == SIGALRM)
  83                 switch_timers(1);
  84
  85 }
  86
  87 void alarm_handler(ARCH_SIGHDLR_PARAM)
  88 {
  89         struct sigcontext *sc;
  90         int enabled;
  91
  92         ARCH_GET_SIGCONTEXT(sc, sig);
  93
  94         enabled = signals_enabled;
  95         if(!signals_enabled){
  96                 if(sig == SIGVTALRM)
  97                         pending |= SIGVTALRM_MASK;
  98                 else pending |= SIGALRM_MASK;
  99
 100                 return;
 101         }
 102
 103         block_signals();
 104
 105         real_alarm_handler(sig, sc);
 106         set_signals(enabled);
 107 }
 108
 109 void set_sigstack(void *sig_stack, int size)
 110 {
 111         stack_t stack = ((stack_t) { .ss_flags  = 0,
 112                                      .ss_sp     = (__ptr_t) sig_stack,
 113                                      .ss_size   = size - sizeof(void *) });
 114
 115         if(sigaltstack(&stack, NULL) != 0)
 116                 panic("enabling signal stack failed, errno = %d\n", errno);
 117 }
 118
 119 void remove_sigstack(void)
 120 {
 121         stack_t stack = ((stack_t) { .ss_flags  = SS_DISABLE,
 122                                      .ss_sp     = NULL,
 123                                      .ss_size   = 0 });
 124
 125         if(sigaltstack(&stack, NULL) != 0)
 126                 panic("disabling signal stack failed, errno = %d\n", errno);
 127 }
 128
 129 void set_handler(int sig, void (*handler)(int), int flags, ...)
 130 {
 131         struct sigaction action;
 132         va_list ap;
 133         sigset_t sig_mask;
 134         int mask;
 135
 136         va_start(ap, flags);
 137         action.sa_handler = handler;
 138         sigemptyset(&action.sa_mask);
 139         while((mask = va_arg(ap, int)) != -1){
 140                 sigaddset(&action.sa_mask, mask);
 141         }
 142         va_end(ap);
 143         action.sa_flags = flags;
 144         action.sa_restorer = NULL;
 145         if(sigaction(sig, &action, NULL) < 0)
 146                 panic("sigaction failed - errno = %d\n", errno);
 147
 148         sigemptyset(&sig_mask);
 149         sigaddset(&sig_mask, sig);
 150         if(sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
 151                 panic("sigprocmask failed - errno = %d\n", errno);
 152 }
 153
 154 int change_sig(int signal, int on)
 155 {
 156         sigset_t sigset, old;
 157
 158         sigemptyset(&sigset);
 159         sigaddset(&sigset, signal);
 160         sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
 161         return(!sigismember(&old, signal));
 162 }
 163
 164 void block_signals(void)
 165 {
 166         signals_enabled = 0;
 167 }
 168
 169 void unblock_signals(void)
 170 {
 171         int save_pending;
 172
 173         if(signals_enabled == 1)
 174                 return;
 175
 176         /* We loop because the IRQ handler returns with interrupts off.  So,
 177          * interrupts may have arrived and we need to re-enable them and
 178          * recheck pending.
 179          */
 180         while(1){
 181                 /* Save and reset save_pending after enabling signals.  This
 182                  * way, pending won't be changed while we're reading it.
 183                  */
 184                 signals_enabled = 1;
 185
 186                 save_pending = pending;
 187                 if(save_pending == 0)
 188                         return;
 189
 190                 pending = 0;
 191
 192                 /* We have pending interrupts, so disable signals, as the
 193                  * handlers expect them off when they are called.  They will
 194                  * be enabled again above.
 195                  */
 196
 197                 signals_enabled = 0;
 198
 199                 /* Deal with SIGIO first because the alarm handler might
 200                  * schedule, leaving the pending SIGIO stranded until we come
 201                  * back here.
 202                  */
 203                 if(save_pending & SIGIO_MASK)
 204                         CHOOSE_MODE_PROC(sig_handler_common_tt,
 205                                          sig_handler_common_skas, SIGIO, NULL);
 206
 207                 if(save_pending & SIGALRM_MASK)
 208                         real_alarm_handler(SIGALRM, NULL);
 209
 210                 if(save_pending & SIGVTALRM_MASK)
 211                         real_alarm_handler(SIGVTALRM, NULL);
 212         }
 213 }
 214
 215 int get_signals(void)
 216 {
 217         return signals_enabled;
 218 }
 219
 220 int set_signals(int enable)
 221 {
 222         int ret;
 223         if(signals_enabled == enable)
 224                 return enable;
 225
 226         ret = signals_enabled;
 227         if(enable)
 228                 unblock_signals();
 229         else block_signals();
 230
 231         return ret;
 232 }
 233
 234 void os_usr1_signal(int on)
 235 {
 236         change_sig(SIGUSR1, on);
 237 }