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