Mon, 25 Feb 2019 21:38:45 +0000
8027434: "-XX:OnOutOfMemoryError" uses fork instead of vfork
Summary: On Linux, use vfork in case of an OOM.
Reviewed-by: dholmes, iklam
aoqi@0 | 1 | /* |
dbuck@8034 | 2 | * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. |
aoqi@0 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
aoqi@0 | 4 | * |
aoqi@0 | 5 | * This code is free software; you can redistribute it and/or modify it |
aoqi@0 | 6 | * under the terms of the GNU General Public License version 2 only, as |
aoqi@0 | 7 | * published by the Free Software Foundation. |
aoqi@0 | 8 | * |
aoqi@0 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
aoqi@0 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
aoqi@0 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
aoqi@0 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
aoqi@0 | 13 | * accompanied this code). |
aoqi@0 | 14 | * |
aoqi@0 | 15 | * You should have received a copy of the GNU General Public License version |
aoqi@0 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
aoqi@0 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
aoqi@0 | 18 | * |
aoqi@0 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
aoqi@0 | 20 | * or visit www.oracle.com if you need additional information or have any |
aoqi@0 | 21 | * questions. |
aoqi@0 | 22 | * |
aoqi@0 | 23 | */ |
aoqi@0 | 24 | |
aoqi@0 | 25 | /* CopyrightVersion 1.2 */ |
aoqi@0 | 26 | |
aoqi@0 | 27 | /* This is a special library that should be loaded before libc & |
aoqi@0 | 28 | * libthread to interpose the signal handler installation functions: |
aoqi@0 | 29 | * sigaction(), signal(), sigset(). |
aoqi@0 | 30 | * Used for signal-chaining. See RFE 4381843. |
aoqi@0 | 31 | */ |
aoqi@0 | 32 | |
aoqi@0 | 33 | #include <signal.h> |
aoqi@0 | 34 | #include <dlfcn.h> |
aoqi@0 | 35 | #include <pthread.h> |
aoqi@0 | 36 | #include <stdio.h> |
aoqi@0 | 37 | #include <stdlib.h> |
aoqi@0 | 38 | #include <stdbool.h> |
dbuck@8034 | 39 | #include <string.h> |
aoqi@0 | 40 | |
aoqi@0 | 41 | #define MAXSIGNUM 32 |
aoqi@0 | 42 | #define MASK(sig) ((unsigned int)1 << sig) |
aoqi@0 | 43 | |
aoqi@0 | 44 | static struct sigaction sact[MAXSIGNUM]; /* saved signal handlers */ |
aoqi@0 | 45 | static unsigned int jvmsigs = 0; /* signals used by jvm */ |
aoqi@0 | 46 | |
dbuck@8034 | 47 | static pthread_key_t reentry_flag_key; |
dbuck@8034 | 48 | static pthread_once_t reentry_key_init_once = PTHREAD_ONCE_INIT; |
dbuck@8034 | 49 | |
aoqi@0 | 50 | /* used to synchronize the installation of signal handlers */ |
aoqi@0 | 51 | static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; |
aoqi@0 | 52 | static pthread_cond_t cond = PTHREAD_COND_INITIALIZER; |
aoqi@0 | 53 | static pthread_t tid = 0; |
aoqi@0 | 54 | |
aoqi@0 | 55 | typedef void (*sa_handler_t)(int); |
aoqi@0 | 56 | typedef void (*sa_sigaction_t)(int, siginfo_t *, void *); |
aoqi@0 | 57 | typedef sa_handler_t (*signal_t)(int, sa_handler_t); |
aoqi@0 | 58 | typedef int (*sigaction_t)(int, const struct sigaction *, struct sigaction *); |
aoqi@0 | 59 | |
aoqi@0 | 60 | static signal_t os_signal = 0; /* os's version of signal()/sigset() */ |
aoqi@0 | 61 | static sigaction_t os_sigaction = 0; /* os's version of sigaction() */ |
aoqi@0 | 62 | |
aoqi@0 | 63 | static bool jvm_signal_installing = false; |
aoqi@0 | 64 | static bool jvm_signal_installed = false; |
aoqi@0 | 65 | |
dbuck@8034 | 66 | #define check_status(cmd) \ |
dbuck@8034 | 67 | do { \ |
dbuck@8034 | 68 | int status = (cmd); \ |
dbuck@8034 | 69 | if (status != 0) { \ |
dbuck@8034 | 70 | printf("error %s (%d) in " #cmd "\n", strerror(status), status); \ |
dbuck@8034 | 71 | exit(1); \ |
dbuck@8034 | 72 | } \ |
dbuck@8034 | 73 | } while (0) |
dbuck@8034 | 74 | |
aoqi@0 | 75 | static void signal_lock() { |
aoqi@0 | 76 | pthread_mutex_lock(&mutex); |
aoqi@0 | 77 | /* When the jvm is installing its set of signal handlers, threads |
aoqi@0 | 78 | * other than the jvm thread should wait */ |
aoqi@0 | 79 | if (jvm_signal_installing) { |
aoqi@0 | 80 | if (tid != pthread_self()) { |
aoqi@0 | 81 | pthread_cond_wait(&cond, &mutex); |
aoqi@0 | 82 | } |
aoqi@0 | 83 | } |
aoqi@0 | 84 | } |
aoqi@0 | 85 | |
aoqi@0 | 86 | static void signal_unlock() { |
aoqi@0 | 87 | pthread_mutex_unlock(&mutex); |
aoqi@0 | 88 | } |
aoqi@0 | 89 | |
dbuck@8034 | 90 | static void reentry_tls_init() { |
dbuck@8034 | 91 | // value for reentry_flag_key will default to NULL (false) |
dbuck@8034 | 92 | check_status(pthread_key_create(&reentry_flag_key, NULL)); |
dbuck@8034 | 93 | } |
dbuck@8034 | 94 | |
aoqi@0 | 95 | static sa_handler_t call_os_signal(int sig, sa_handler_t disp, |
aoqi@0 | 96 | bool is_sigset) { |
dbuck@8034 | 97 | sa_handler_t res; |
dbuck@8034 | 98 | |
aoqi@0 | 99 | if (os_signal == NULL) { |
aoqi@0 | 100 | if (!is_sigset) { |
aoqi@0 | 101 | os_signal = (signal_t)dlsym(RTLD_NEXT, "signal"); |
aoqi@0 | 102 | } else { |
aoqi@0 | 103 | os_signal = (signal_t)dlsym(RTLD_NEXT, "sigset"); |
aoqi@0 | 104 | } |
aoqi@0 | 105 | if (os_signal == NULL) { |
aoqi@0 | 106 | printf("%s\n", dlerror()); |
aoqi@0 | 107 | exit(0); |
aoqi@0 | 108 | } |
aoqi@0 | 109 | } |
dbuck@8034 | 110 | check_status(pthread_once(&reentry_key_init_once, reentry_tls_init)); |
dbuck@8034 | 111 | // set reentry_flag_key to non-NULL to show reentry |
dbuck@8034 | 112 | check_status(pthread_setspecific(reentry_flag_key, &res)); |
dbuck@8034 | 113 | res = (*os_signal)(sig, disp); |
dbuck@8034 | 114 | check_status(pthread_setspecific(reentry_flag_key, NULL)); |
dbuck@8034 | 115 | return res; |
aoqi@0 | 116 | } |
aoqi@0 | 117 | |
aoqi@0 | 118 | static void save_signal_handler(int sig, sa_handler_t disp) { |
aoqi@0 | 119 | sigset_t set; |
aoqi@0 | 120 | sact[sig].sa_handler = disp; |
aoqi@0 | 121 | sigemptyset(&set); |
aoqi@0 | 122 | sact[sig].sa_mask = set; |
aoqi@0 | 123 | sact[sig].sa_flags = 0; |
aoqi@0 | 124 | } |
aoqi@0 | 125 | |
aoqi@0 | 126 | static sa_handler_t set_signal(int sig, sa_handler_t disp, bool is_sigset) { |
aoqi@0 | 127 | sa_handler_t oldhandler; |
aoqi@0 | 128 | bool sigused; |
aoqi@0 | 129 | |
aoqi@0 | 130 | signal_lock(); |
aoqi@0 | 131 | |
aoqi@0 | 132 | sigused = (MASK(sig) & jvmsigs) != 0; |
aoqi@0 | 133 | if (jvm_signal_installed && sigused) { |
aoqi@0 | 134 | /* jvm has installed its signal handler for this signal. */ |
aoqi@0 | 135 | /* Save the handler. Don't really install it. */ |
aoqi@0 | 136 | oldhandler = sact[sig].sa_handler; |
aoqi@0 | 137 | save_signal_handler(sig, disp); |
aoqi@0 | 138 | |
aoqi@0 | 139 | signal_unlock(); |
aoqi@0 | 140 | return oldhandler; |
aoqi@0 | 141 | } else if (jvm_signal_installing) { |
aoqi@0 | 142 | /* jvm is installing its signal handlers. Install the new |
aoqi@0 | 143 | * handlers and save the old ones. jvm uses sigaction(). |
aoqi@0 | 144 | * Leave the piece here just in case. */ |
aoqi@0 | 145 | oldhandler = call_os_signal(sig, disp, is_sigset); |
aoqi@0 | 146 | save_signal_handler(sig, oldhandler); |
aoqi@0 | 147 | |
aoqi@0 | 148 | /* Record the signals used by jvm */ |
aoqi@0 | 149 | jvmsigs |= MASK(sig); |
aoqi@0 | 150 | |
aoqi@0 | 151 | signal_unlock(); |
aoqi@0 | 152 | return oldhandler; |
aoqi@0 | 153 | } else { |
aoqi@0 | 154 | /* jvm has no relation with this signal (yet). Install the |
aoqi@0 | 155 | * the handler. */ |
aoqi@0 | 156 | oldhandler = call_os_signal(sig, disp, is_sigset); |
aoqi@0 | 157 | |
aoqi@0 | 158 | signal_unlock(); |
aoqi@0 | 159 | return oldhandler; |
aoqi@0 | 160 | } |
aoqi@0 | 161 | } |
aoqi@0 | 162 | |
aoqi@0 | 163 | sa_handler_t signal(int sig, sa_handler_t disp) { |
aoqi@0 | 164 | return set_signal(sig, disp, false); |
aoqi@0 | 165 | } |
aoqi@0 | 166 | |
aoqi@0 | 167 | sa_handler_t sigset(int sig, sa_handler_t disp) { |
aoqi@0 | 168 | printf("sigset() is not supported by BSD"); |
aoqi@0 | 169 | exit(0); |
aoqi@0 | 170 | } |
aoqi@0 | 171 | |
aoqi@0 | 172 | static int call_os_sigaction(int sig, const struct sigaction *act, |
aoqi@0 | 173 | struct sigaction *oact) { |
aoqi@0 | 174 | if (os_sigaction == NULL) { |
aoqi@0 | 175 | os_sigaction = (sigaction_t)dlsym(RTLD_NEXT, "sigaction"); |
aoqi@0 | 176 | if (os_sigaction == NULL) { |
aoqi@0 | 177 | printf("%s\n", dlerror()); |
aoqi@0 | 178 | exit(0); |
aoqi@0 | 179 | } |
aoqi@0 | 180 | } |
aoqi@0 | 181 | return (*os_sigaction)(sig, act, oact); |
aoqi@0 | 182 | } |
aoqi@0 | 183 | |
aoqi@0 | 184 | int sigaction(int sig, const struct sigaction *act, struct sigaction *oact) { |
aoqi@0 | 185 | int res; |
aoqi@0 | 186 | bool sigused; |
aoqi@0 | 187 | struct sigaction oldAct; |
aoqi@0 | 188 | |
dbuck@8034 | 189 | check_status(pthread_once(&reentry_key_init_once, reentry_tls_init)); |
dbuck@8034 | 190 | if (pthread_getspecific(reentry_flag_key) != NULL) { |
dbuck@8034 | 191 | return call_os_sigaction(sig, act, oact); |
dbuck@8034 | 192 | } |
dbuck@8034 | 193 | |
aoqi@0 | 194 | signal_lock(); |
aoqi@0 | 195 | |
aoqi@0 | 196 | sigused = (MASK(sig) & jvmsigs) != 0; |
aoqi@0 | 197 | if (jvm_signal_installed && sigused) { |
aoqi@0 | 198 | /* jvm has installed its signal handler for this signal. */ |
aoqi@0 | 199 | /* Save the handler. Don't really install it. */ |
aoqi@0 | 200 | if (oact != NULL) { |
aoqi@0 | 201 | *oact = sact[sig]; |
aoqi@0 | 202 | } |
aoqi@0 | 203 | if (act != NULL) { |
aoqi@0 | 204 | sact[sig] = *act; |
aoqi@0 | 205 | } |
aoqi@0 | 206 | |
aoqi@0 | 207 | signal_unlock(); |
aoqi@0 | 208 | return 0; |
aoqi@0 | 209 | } else if (jvm_signal_installing) { |
aoqi@0 | 210 | /* jvm is installing its signal handlers. Install the new |
aoqi@0 | 211 | * handlers and save the old ones. */ |
aoqi@0 | 212 | res = call_os_sigaction(sig, act, &oldAct); |
aoqi@0 | 213 | sact[sig] = oldAct; |
aoqi@0 | 214 | if (oact != NULL) { |
aoqi@0 | 215 | *oact = oldAct; |
aoqi@0 | 216 | } |
aoqi@0 | 217 | |
aoqi@0 | 218 | /* Record the signals used by jvm */ |
aoqi@0 | 219 | jvmsigs |= MASK(sig); |
aoqi@0 | 220 | |
aoqi@0 | 221 | signal_unlock(); |
aoqi@0 | 222 | return res; |
aoqi@0 | 223 | } else { |
aoqi@0 | 224 | /* jvm has no relation with this signal (yet). Install the |
aoqi@0 | 225 | * the handler. */ |
aoqi@0 | 226 | res = call_os_sigaction(sig, act, oact); |
aoqi@0 | 227 | |
aoqi@0 | 228 | signal_unlock(); |
aoqi@0 | 229 | return res; |
aoqi@0 | 230 | } |
aoqi@0 | 231 | } |
aoqi@0 | 232 | |
aoqi@0 | 233 | /* The three functions for the jvm to call into */ |
aoqi@0 | 234 | void JVM_begin_signal_setting() { |
aoqi@0 | 235 | signal_lock(); |
aoqi@0 | 236 | jvm_signal_installing = true; |
aoqi@0 | 237 | tid = pthread_self(); |
aoqi@0 | 238 | signal_unlock(); |
aoqi@0 | 239 | } |
aoqi@0 | 240 | |
aoqi@0 | 241 | void JVM_end_signal_setting() { |
aoqi@0 | 242 | signal_lock(); |
aoqi@0 | 243 | jvm_signal_installed = true; |
aoqi@0 | 244 | jvm_signal_installing = false; |
aoqi@0 | 245 | pthread_cond_broadcast(&cond); |
aoqi@0 | 246 | signal_unlock(); |
aoqi@0 | 247 | } |
aoqi@0 | 248 | |
aoqi@0 | 249 | struct sigaction *JVM_get_signal_action(int sig) { |
aoqi@0 | 250 | /* Does race condition make sense here? */ |
aoqi@0 | 251 | if ((MASK(sig) & jvmsigs) != 0) { |
aoqi@0 | 252 | return &sact[sig]; |
aoqi@0 | 253 | } |
aoqi@0 | 254 | return NULL; |
aoqi@0 | 255 | } |