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[xemacs-hg @ 2005-11-25 01:41:31 by crestani] Incremental Garbage Collector
author crestani
date Fri, 25 Nov 2005 01:42:08 +0000
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children d81b1754aab1
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3091:c22d8984148c 3092:141c2920ea48
1 /* Virtual diry bit implementation for XEmacs.
2 Copyright (C) 2005 Marcus Crestani.
3
4 This file is part of XEmacs.
5
6 XEmacs is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 2, or (at your option) any
9 later version.
10
11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with XEmacs; see the file COPYING. If not, write to
18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
20
21 /* Synched up with: Not in FSF. */
22
23 #include <config.h>
24 #include "lisp.h"
25 #include "gc.h"
26 #include "mc-alloc.h"
27 #include "vdb.h"
28
29 #include <errno.h>
30 #include <signal.h>
31 #include <sys/mman.h>
32
33 #if defined (HAVE_SIGACTION)
34 # if defined (HAVE_STRUCT_SIGINFO_SI_ADDR)
35 # define FAULT_HANDLER_ARGUMENTS \
36 int signum, struct siginfo *siginfo, void *UNUSED (ctx)
37 # define GET_FAULT_ADDRESS siginfo->si_addr
38 # elif defined (HAVE_SIGINFO_T_SI_ADDR)
39 # define FAULT_HANDLER_ARGUMENTS \
40 int signum, siginfo_t *siginfo, void *UNUSED (ctx)
41 # define GET_FAULT_ADDRESS siginfo->si_addr
42 # endif
43 # define USE_SIGACTION
44 # define FAULT_HANDLER_REMOVE_HANDLER
45 #elif defined (HAVE_SIGNAL)
46 # define FAULT_HANDLER_ARGUMENTS int signum, struct sigcontext sc
47 # define GET_FAULT_ADDRESS (void *) sc.cr2
48 # define USE_SIGNAL
49 #endif
50
51
52 #ifdef USE_SIGACTION
53 struct sigaction act, segv_oact, bus_oact;
54 #endif /* USE_SIGACTION */
55
56 #ifdef USE_SIGNAL
57 sighandler_t segv_oact, bus_oact;
58 #endif /* USE_SIGNAL */
59
60 void vdb_remove_signal_handler (void);
61
62 void
63 vdb_fault_handler (FAULT_HANDLER_ARGUMENTS)
64 {
65 if (write_barrier_enabled
66 && (fault_on_protected_page (GET_FAULT_ADDRESS)))
67 {
68 vdb_designate_modified (GET_FAULT_ADDRESS);
69 unprotect_page_and_mark_dirty (GET_FAULT_ADDRESS);
70 #ifdef FAULT_HANDLER_REINSTALL_HANDLER
71 vdb_install_signal_handler ();
72 #endif /* FAULT_HANDLER_REINSTALL_HANDLER */
73 }
74 else /* default sigsegv handler */
75 {
76 char *signal_name;
77 if (signum == SIGSEGV)
78 signal_name = "SIGSEGV";
79 else if (signum == SIGBUS)
80 signal_name = "SIGBUS";
81 else
82 ABORT (); /* something weird happened: wrong signal caught */
83 fprintf (stderr, "\n\nFatal Error: Received %s (%d) for address 0x%x\n",
84 signal_name, signum, (int) GET_FAULT_ADDRESS);
85 #ifdef FAULT_HANDLER_CALL_PREVIOUS_HANDLER
86 if (signum == SIGSEGV)
87 segv_oact (signum);
88 else if (signum == SIGBUS)
89 bus_oact (signum);
90 #endif /* FAULT_HANDLER_CALL_PREVIOUS_HANDLER */
91 #ifdef FAULT_HANDLER_REMOVE_HANDLER
92 vdb_remove_signal_handler ();
93 #endif /* FAULT_HANDLER_REMOVE_HANDLER */
94 }
95 }
96
97 void
98 vdb_remove_signal_handler (void)
99 {
100 #ifdef USE_SIGACTION
101 sigaction(SIGSEGV, &segv_oact, 0);
102 sigaction(SIGBUS, &bus_oact, 0);
103 #endif /* USE_SIGACTION */
104 #ifdef USE_SIGNAL
105 signal (SIGSEGV, segv_oact);
106 signal (SIGBUS, bus_oact);
107 #endif
108 }
109
110 void
111 vdb_install_signal_handler (void)
112 {
113 /* See init_signals_very_early () in signal.c. */
114 if (noninteractive && !initialized)
115 {
116 allow_incremental_gc = 0;
117 return;
118 }
119
120 #ifdef USE_SIGACTION
121 memset(&act, sizeof(struct sigaction), 0);
122 act.sa_sigaction = vdb_fault_handler;
123 sigemptyset (&act.sa_mask);
124 act.sa_flags = SA_SIGINFO;
125 sigaction (SIGSEGV, &act, &segv_oact);
126 sigaction (SIGBUS, &act, &bus_oact);
127 allow_incremental_gc = 1;
128 #endif /* USE_SIGACTION */
129 #ifdef USE_SIGNAL
130 segv_oact = signal (SIGSEGV, (void (*)(int)) vdb_fault_handler);
131 bus_oact = signal (SIGBUS, (void (*)(int)) vdb_fault_handler);
132 #endif /* USE_SIGNAL */
133 }
134
135 void
136 vdb_protect (void *ptr, EMACS_INT len)
137 {
138 if (mprotect (ptr, len, PROT_READ))
139 {
140 perror ("Couldn't mprotect");
141 ABORT ();
142 }
143 }
144
145 void
146 vdb_unprotect (void *ptr, EMACS_INT len)
147 {
148 if (mprotect (ptr, len, PROT_READ | PROT_WRITE))
149 {
150 perror ("Couldn't mprotect");
151 ABORT ();
152 }
153 }