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 extern void do_boot_timer_handler(struct sigcontext * sc);
 110
 111 void boot_timer_handler(ARCH_SIGHDLR_PARAM)
 112 {
 113         struct sigcontext *sc;
 114         int enabled;
 115
 116         ARCH_GET_SIGCONTEXT(sc, sig);
 117
 118         enabled = signals_enabled;
 119         if(!enabled){
 120                 if(sig == SIGVTALRM)
 121                         pending |= SIGVTALRM_MASK;
 122                 else pending |= SIGALRM_MASK;
 123                 return;
 124         }
 125
 126         block_signals();
 127
 128         do_boot_timer_handler(sc);
 129         set_signals(enabled);
 130 }
 131
 132 void set_sigstack(void *sig_stack, int size)
 133 {
 134         stack_t stack = ((stack_t) { .ss_flags  = 0,
 135                                      .ss_sp     = (__ptr_t) sig_stack,
 136                                      .ss_size   = size - sizeof(void *) });
 137
 138         if(sigaltstack(&stack, NULL) != 0)
 139                 panic("enabling signal stack failed, errno = %d\n", errno);
 140 }
 141
 142 void remove_sigstack(void)
 143 {
 144         stack_t stack = ((stack_t) { .ss_flags  = SS_DISABLE,
 145                                      .ss_sp     = NULL,
 146                                      .ss_size   = 0 });
 147
 148         if(sigaltstack(&stack, NULL) != 0)
 149                 panic("disabling signal stack failed, errno = %d\n", errno);
 150 }
 151
 152 void set_handler(int sig, void (*handler)(int), int flags, ...)
 153 {
 154         struct sigaction action;
 155         va_list ap;
 156         sigset_t sig_mask;
 157         int mask;
 158
 159         va_start(ap, flags);
 160         action.sa_handler = handler;
 161         sigemptyset(&action.sa_mask);
 162         while((mask = va_arg(ap, int)) != -1){
 163                 sigaddset(&action.sa_mask, mask);
 164         }
 165         va_end(ap);
 166         action.sa_flags = flags;
 167         action.sa_restorer = NULL;
 168         if(sigaction(sig, &action, NULL) < 0)
 169                 panic("sigaction failed - errno = %d\n", errno);
 170
 171         sigemptyset(&sig_mask);
 172         sigaddset(&sig_mask, sig);
 173         if(sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
 174                 panic("sigprocmask failed - errno = %d\n", errno);
 175 }
 176
 177 int change_sig(int signal, int on)
 178 {
 179         sigset_t sigset, old;
 180
 181         sigemptyset(&sigset);
 182         sigaddset(&sigset, signal);
 183         sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
 184         return(!sigismember(&old, signal));
 185 }
 186
 187 void block_signals(void)
 188 {
 189         signals_enabled = 0;
 190 }
 191
 192 void unblock_signals(void)
 193 {
 194         int save_pending;
 195
 196         if(signals_enabled == 1)
 197                 return;
 198
 199         /* We loop because the IRQ handler returns with interrupts off.  So,
 200          * interrupts may have arrived and we need to re-enable them and
 201          * recheck pending.
 202          */
 203         while(1){
 204                 /* Save and reset save_pending after enabling signals.  This
 205                  * way, pending won't be changed while we're reading it.
 206                  */
 207                 signals_enabled = 1;
 208
 209                 save_pending = pending;
 210                 if(save_pending == 0)
 211                         return;
 212
 213                 pending = 0;
 214
 215                 /* We have pending interrupts, so disable signals, as the
 216                  * handlers expect them off when they are called.  They will
 217                  * be enabled again above.
 218                  */
 219
 220                 signals_enabled = 0;
 221
 222                 /* Deal with SIGIO first because the alarm handler might
 223                  * schedule, leaving the pending SIGIO stranded until we come
 224                  * back here.
 225                  */
 226                 if(save_pending & SIGIO_MASK)
 227                         CHOOSE_MODE_PROC(sig_handler_common_tt,
 228                                          sig_handler_common_skas, SIGIO, NULL);
 229
 230                 if(save_pending & SIGALRM_MASK)
 231                         real_alarm_handler(SIGALRM, NULL);
 232
 233                 if(save_pending & SIGVTALRM_MASK)
 234                         real_alarm_handler(SIGVTALRM, NULL);
 235         }
 236 }
 237
 238 int get_signals(void)
 239 {
 240         return signals_enabled;
 241 }
 242
 243 int set_signals(int enable)
 244 {
 245         int ret;
 246         if(signals_enabled == enable)
 247                 return enable;
 248
 249         ret = signals_enabled;
 250         if(enable)
 251                 unblock_signals();
 252         else block_signals();
 253
 254         return ret;
 255 }
 256
 257 void os_usr1_signal(int on)
 258 {
 259         change_sig(SIGUSR1, on);
 260 }