Bug Summary

File:jdk/src/hotspot/os/posix/signals_posix.cpp
Warning:line 1304, column 5
Called function pointer is null (null dereference)

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name signals_posix.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 2 -mthread-model posix -fno-delete-null-pointer-checks -mframe-pointer=all -relaxed-aliasing -fmath-errno -fno-rounding-math -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -dwarf-column-info -fno-split-dwarf-inlining -debugger-tuning=gdb -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/hotspot/variant-server/libjvm/objs/precompiled -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D _GNU_SOURCE -D _REENTRANT -D LIBC=gnu -D LINUX -D VM_LITTLE_ENDIAN -D _LP64=1 -D ASSERT -D CHECK_UNHANDLED_OOPS -D TARGET_ARCH_x86 -D INCLUDE_SUFFIX_OS=_linux -D INCLUDE_SUFFIX_CPU=_x86 -D INCLUDE_SUFFIX_COMPILER=_gcc -D TARGET_COMPILER_gcc -D AMD64 -D HOTSPOT_LIB_ARCH="amd64" -D COMPILER1 -D COMPILER2 -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/hotspot/variant-server/gensrc/adfiles -I /home/daniel/Projects/java/jdk/src/hotspot/share -I /home/daniel/Projects/java/jdk/src/hotspot/os/linux -I /home/daniel/Projects/java/jdk/src/hotspot/os/posix -I /home/daniel/Projects/java/jdk/src/hotspot/cpu/x86 -I /home/daniel/Projects/java/jdk/src/hotspot/os_cpu/linux_x86 -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/hotspot/variant-server/gensrc -I /home/daniel/Projects/java/jdk/src/hotspot/share/precompiled -I /home/daniel/Projects/java/jdk/src/hotspot/share/include -I /home/daniel/Projects/java/jdk/src/hotspot/os/posix/include -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/support/modules_include/java.base -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/support/modules_include/java.base/linux -I /home/daniel/Projects/java/jdk/src/java.base/share/native/libjimage -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/hotspot/variant-server/gensrc/adfiles -I /home/daniel/Projects/java/jdk/src/hotspot/share -I /home/daniel/Projects/java/jdk/src/hotspot/os/linux -I /home/daniel/Projects/java/jdk/src/hotspot/os/posix -I /home/daniel/Projects/java/jdk/src/hotspot/cpu/x86 -I /home/daniel/Projects/java/jdk/src/hotspot/os_cpu/linux_x86 -I /home/daniel/Projects/java/jdk/build/linux-x86_64-server-fastdebug/hotspot/variant-server/gensrc -D _FORTIFY_SOURCE=2 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/c++/7.5.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/x86_64-linux-gnu/c++/7.5.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/x86_64-linux-gnu/c++/7.5.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/c++/7.5.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -Wno-format-zero-length -Wno-unused-parameter -Wno-unused -Wno-parentheses -Wno-comment -Wno-unknown-pragmas -Wno-address -Wno-delete-non-virtual-dtor -Wno-char-subscripts -Wno-array-bounds -Wno-int-in-bool-context -Wno-ignored-qualifiers -Wno-missing-field-initializers -Wno-implicit-fallthrough -Wno-empty-body -Wno-strict-overflow -Wno-sequence-point -Wno-maybe-uninitialized -Wno-misleading-indentation -Wno-cast-function-type -Wno-shift-negative-value -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /home/daniel/Projects/java/jdk/make/hotspot -ferror-limit 19 -fmessage-length 0 -fvisibility hidden -stack-protector 1 -fno-rtti -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -faddrsig -o /home/daniel/Projects/java/scan/2021-12-21-193737-8510-1 -x c++ /home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp
1/*
2 * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#include "precompiled.hpp"
26
27#include "jvm.h"
28#include "logging/log.hpp"
29#include "runtime/atomic.hpp"
30#include "runtime/globals.hpp"
31#include "runtime/interfaceSupport.inline.hpp"
32#include "runtime/java.hpp"
33#include "runtime/os.hpp"
34#include "runtime/osThread.hpp"
35#include "runtime/semaphore.inline.hpp"
36#include "runtime/stubRoutines.hpp"
37#include "runtime/thread.hpp"
38#include "signals_posix.hpp"
39#include "utilities/events.hpp"
40#include "utilities/ostream.hpp"
41#include "utilities/vmError.hpp"
42
43#ifdef ZERO
44// See stubGenerator_zero.cpp
45#include <setjmp.h>
46extern sigjmp_buf* get_jmp_buf_for_continuation();
47#endif
48
49#include <signal.h>
50
51
52static const char* get_signal_name(int sig, char* out, size_t outlen);
53
54// Returns address of a handler associated with the given sigaction
55static address get_signal_handler(const struct sigaction* action);
56
57#define HANDLER_IS(handler, address)((handler) == ((void*)((address_word)((address))))) ((handler) == CAST_FROM_FN_PTR(void*, (address))((void*)((address_word)((address)))))
58#define HANDLER_IS_IGN(handler)(((handler) == ((void*)((address_word)((((__sighandler_t) 1))
))))) (HANDLER_IS(handler, SIG_IGN)((handler) == ((void*)((address_word)((((__sighandler_t) 1)))
))))
59#define HANDLER_IS_DFL(handler)(((handler) == ((void*)((address_word)((((__sighandler_t) 0))
))))) (HANDLER_IS(handler, SIG_DFL)((handler) == ((void*)((address_word)((((__sighandler_t) 0)))
))))
60#define HANDLER_IS_IGN_OR_DFL(handler)((((handler) == ((void*)((address_word)((((__sighandler_t) 1)
)))))) || (((handler) == ((void*)((address_word)((((__sighandler_t
) 0)))))))) (HANDLER_IS_IGN(handler)(((handler) == ((void*)((address_word)((((__sighandler_t) 1))
))))) || HANDLER_IS_DFL(handler)(((handler) == ((void*)((address_word)((((__sighandler_t) 0))
))))))
61
62// Various signal related mechanism are laid out in the following order:
63//
64// sun.misc.Signal
65// signal chaining
66// signal handling (except suspend/resume)
67// suspend/resume
68
69// Helper function to strip any flags from a sigaction sa_flag
70// which are not needed for semantic comparison (see remarks below
71// about SA_RESTORER on Linux).
72// Also to work around the fact that not all platforms define sa_flags
73// as signed int (looking at you, zlinux).
74static int get_sanitized_sa_flags(const struct sigaction* sa) {
75 int f = (int) sa->sa_flags;
76#ifdef LINUX1
77 // Glibc on Linux uses the SA_RESTORER flag to indicate
78 // the use of a "signal trampoline". We have no interest
79 // in this flag and need to ignore it when checking our
80 // own flag settings.
81 // Note: SA_RESTORER is not exposed through signal.h so we
82 // have to hardcode its 0x04000000 value here.
83 const int sa_restorer_flag = 0x04000000;
84 f &= ~sa_restorer_flag;
85#endif // LINUX
86 return f;
87}
88
89// Todo: provide a os::get_max_process_id() or similar. Number of processes
90// may have been configured, can be read more accurately from proc fs etc.
91#ifndef MAX_PID2147483647
92 #define MAX_PID2147483647 INT_MAX2147483647
93#endif
94#define IS_VALID_PID(p)(p > 0 && p < 2147483647) (p > 0 && p < MAX_PID2147483647)
95
96#define NUM_IMPORTANT_SIGS32 32
97
98extern "C" {
99 typedef void (*sa_handler_t)(int);
100 typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
101}
102
103// At various places we store handler information for each installed handler.
104// SavedSignalHandlers is a helper class for those cases, keeping an array of sigaction
105// structures.
106class SavedSignalHandlers {
107 // Note: NSIG can be largish, depending on platform, and this array is expected
108 // to be sparsely populated. To save space the contained structures are
109 // C-heap allocated. Since they only get added outside of signal handling
110 // this is no problem.
111 struct sigaction* _sa[NSIG(64 + 1)];
112
113 bool check_signal_number(int sig) const {
114 assert(sig > 0 && sig < NSIG, "invalid signal number %d", sig)do { if (!(sig > 0 && sig < (64 + 1))) { (*g_assert_poison
) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 114, "assert(" "sig > 0 && sig < (64 + 1)" ") failed"
, "invalid signal number %d", sig); ::breakpoint(); } } while
(0);
115 return sig > 0 && sig < NSIG(64 + 1);
116 }
117
118public:
119
120 SavedSignalHandlers() {
121 ::memset(_sa, 0, sizeof(_sa));
122 }
123
124 ~SavedSignalHandlers() {
125 for (int i = 0; i < NSIG(64 + 1); i ++) {
126 FREE_C_HEAP_OBJ(_sa[i])FreeHeap((char*)_sa[i]);;
127 }
128 }
129
130 void set(int sig, const struct sigaction* act) {
131 if (check_signal_number(sig)) {
132 assert(_sa[sig] == NULL, "Overwriting signal handler?")do { if (!(_sa[sig] == __null)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 132, "assert(" "_sa[sig] == __null" ") failed", "Overwriting signal handler?"
); ::breakpoint(); } } while (0);
133 _sa[sig] = NEW_C_HEAP_OBJ(struct sigaction, mtInternal)(struct sigaction*) (AllocateHeap((1) * sizeof(struct sigaction
), mtInternal));
134 *_sa[sig] = *act;
135 }
136 }
137
138 const struct sigaction* get(int sig) const {
139 if (check_signal_number(sig)) {
140 return _sa[sig];
141 }
142 return NULL__null;
143 }
144};
145
146
147debug_only(static bool signal_sets_initialized = false)static bool signal_sets_initialized = false;
148static sigset_t unblocked_sigs, vm_sigs, preinstalled_sigs;
149
150// Our own signal handlers should never ever get replaced by a third party one.
151// To check that, and to aid with diagnostics, store a copy of the handler setup
152// and compare it periodically against reality (see os::run_periodic_checks()).
153static bool check_signals = true;
154static SavedSignalHandlers vm_handlers;
155static bool do_check_signal_periodically[NSIG(64 + 1)] = { 0 };
156
157// For signal-chaining:
158// if chaining is active, chained_handlers contains all handlers which we
159// replaced with our own and to which we must delegate.
160static SavedSignalHandlers chained_handlers;
161static bool libjsig_is_loaded = false;
162typedef struct sigaction *(*get_signal_t)(int);
163static get_signal_t get_signal_action = NULL__null;
164
165// suspend/resume support
166#if defined(__APPLE__)
167 static OSXSemaphore sr_semaphore;
168#else
169 static PosixSemaphore sr_semaphore;
170#endif
171
172// Signal number used to suspend/resume a thread
173// do not use any signal number less than SIGSEGV, see 4355769
174int PosixSignals::SR_signum = SIGUSR212;
175
176// sun.misc.Signal support
177static Semaphore* sig_semaphore = NULL__null;
178// a counter for each possible signal value
179static volatile jint pending_signals[NSIG(64 + 1)+1] = { 0 };
180
181static const struct {
182 int sig; const char* name;
183} g_signal_info[] = {
184 { SIGABRT6, "SIGABRT" },
185#ifdef SIGAIO
186 { SIGAIO, "SIGAIO" },
187#endif
188 { SIGALRM14, "SIGALRM" },
189#ifdef SIGALRM1
190 { SIGALRM1, "SIGALRM1" },
191#endif
192 { SIGBUS7, "SIGBUS" },
193#ifdef SIGCANCEL
194 { SIGCANCEL, "SIGCANCEL" },
195#endif
196 { SIGCHLD17, "SIGCHLD" },
197#ifdef SIGCLD17
198 { SIGCLD17, "SIGCLD" },
199#endif
200 { SIGCONT18, "SIGCONT" },
201#ifdef SIGCPUFAIL
202 { SIGCPUFAIL, "SIGCPUFAIL" },
203#endif
204#ifdef SIGDANGER
205 { SIGDANGER, "SIGDANGER" },
206#endif
207#ifdef SIGDIL
208 { SIGDIL, "SIGDIL" },
209#endif
210#ifdef SIGEMT
211 { SIGEMT, "SIGEMT" },
212#endif
213 { SIGFPE8, "SIGFPE" },
214#ifdef SIGFREEZE
215 { SIGFREEZE, "SIGFREEZE" },
216#endif
217#ifdef SIGGFAULT
218 { SIGGFAULT, "SIGGFAULT" },
219#endif
220#ifdef SIGGRANT
221 { SIGGRANT, "SIGGRANT" },
222#endif
223 { SIGHUP1, "SIGHUP" },
224 { SIGILL4, "SIGILL" },
225#ifdef SIGINFO
226 { SIGINFO, "SIGINFO" },
227#endif
228 { SIGINT2, "SIGINT" },
229#ifdef SIGIO29
230 { SIGIO29, "SIGIO" },
231#endif
232#ifdef SIGIOINT
233 { SIGIOINT, "SIGIOINT" },
234#endif
235#ifdef SIGIOT6
236// SIGIOT is there for BSD compatibility, but on most Unices just a
237// synonym for SIGABRT. The result should be "SIGABRT", not
238// "SIGIOT".
239#if (SIGIOT6 != SIGABRT6 )
240 { SIGIOT6, "SIGIOT" },
241#endif
242#endif
243#ifdef SIGKAP
244 { SIGKAP, "SIGKAP" },
245#endif
246 { SIGKILL9, "SIGKILL" },
247#ifdef SIGLOST
248 { SIGLOST, "SIGLOST" },
249#endif
250#ifdef SIGLWP
251 { SIGLWP, "SIGLWP" },
252#endif
253#ifdef SIGLWPTIMER
254 { SIGLWPTIMER, "SIGLWPTIMER" },
255#endif
256#ifdef SIGMIGRATE
257 { SIGMIGRATE, "SIGMIGRATE" },
258#endif
259#ifdef SIGMSG
260 { SIGMSG, "SIGMSG" },
261#endif
262 { SIGPIPE13, "SIGPIPE" },
263#ifdef SIGPOLL29
264 { SIGPOLL29, "SIGPOLL" },
265#endif
266#ifdef SIGPRE
267 { SIGPRE, "SIGPRE" },
268#endif
269 { SIGPROF27, "SIGPROF" },
270#ifdef SIGPTY
271 { SIGPTY, "SIGPTY" },
272#endif
273#ifdef SIGPWR30
274 { SIGPWR30, "SIGPWR" },
275#endif
276 { SIGQUIT3, "SIGQUIT" },
277#ifdef SIGRECONFIG
278 { SIGRECONFIG, "SIGRECONFIG" },
279#endif
280#ifdef SIGRECOVERY
281 { SIGRECOVERY, "SIGRECOVERY" },
282#endif
283#ifdef SIGRESERVE
284 { SIGRESERVE, "SIGRESERVE" },
285#endif
286#ifdef SIGRETRACT
287 { SIGRETRACT, "SIGRETRACT" },
288#endif
289#ifdef SIGSAK
290 { SIGSAK, "SIGSAK" },
291#endif
292 { SIGSEGV11, "SIGSEGV" },
293#ifdef SIGSOUND
294 { SIGSOUND, "SIGSOUND" },
295#endif
296#ifdef SIGSTKFLT16
297 { SIGSTKFLT16, "SIGSTKFLT" },
298#endif
299 { SIGSTOP19, "SIGSTOP" },
300 { SIGSYS31, "SIGSYS" },
301#ifdef SIGSYSERROR
302 { SIGSYSERROR, "SIGSYSERROR" },
303#endif
304#ifdef SIGTALRM
305 { SIGTALRM, "SIGTALRM" },
306#endif
307 { SIGTERM15, "SIGTERM" },
308#ifdef SIGTHAW
309 { SIGTHAW, "SIGTHAW" },
310#endif
311 { SIGTRAP5, "SIGTRAP" },
312#ifdef SIGTSTP20
313 { SIGTSTP20, "SIGTSTP" },
314#endif
315 { SIGTTIN21, "SIGTTIN" },
316 { SIGTTOU22, "SIGTTOU" },
317#ifdef SIGURG23
318 { SIGURG23, "SIGURG" },
319#endif
320 { SIGUSR110, "SIGUSR1" },
321 { SIGUSR212, "SIGUSR2" },
322#ifdef SIGVIRT
323 { SIGVIRT, "SIGVIRT" },
324#endif
325 { SIGVTALRM26, "SIGVTALRM" },
326#ifdef SIGWAITING
327 { SIGWAITING, "SIGWAITING" },
328#endif
329#ifdef SIGWINCH28
330 { SIGWINCH28, "SIGWINCH" },
331#endif
332#ifdef SIGWINDOW
333 { SIGWINDOW, "SIGWINDOW" },
334#endif
335 { SIGXCPU24, "SIGXCPU" },
336 { SIGXFSZ25, "SIGXFSZ" },
337#ifdef SIGXRES
338 { SIGXRES, "SIGXRES" },
339#endif
340 { -1, NULL__null }
341};
342
343////////////////////////////////////////////////////////////////////////////////
344// sun.misc.Signal support
345
346void jdk_misc_signal_init() {
347 // Initialize signal structures
348 ::memset((void*)pending_signals, 0, sizeof(pending_signals));
349
350 // Initialize signal semaphore
351 sig_semaphore = new Semaphore();
352}
353
354void os::signal_notify(int sig) {
355 if (sig_semaphore != NULL__null) {
356 Atomic::inc(&pending_signals[sig]);
357 sig_semaphore->signal();
358 } else {
359 // Signal thread is not created with ReduceSignalUsage and jdk_misc_signal_init
360 // initialization isn't called.
361 assert(ReduceSignalUsage, "signal semaphore should be created")do { if (!(ReduceSignalUsage)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 361, "assert(" "ReduceSignalUsage" ") failed", "signal semaphore should be created"
); ::breakpoint(); } } while (0);
362 }
363}
364
365static int check_pending_signals() {
366 for (;;) {
367 for (int i = 0; i < NSIG(64 + 1) + 1; i++) {
368 jint n = pending_signals[i];
369 if (n > 0 && n == Atomic::cmpxchg(&pending_signals[i], n, n - 1)) {
370 return i;
371 }
372 }
373 sig_semaphore->wait_with_safepoint_check(JavaThread::current());
374 }
375 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 375); ::breakpoint(); } while (0);
376 return 0; // Satisfy compiler
377}
378
379int os::signal_wait() {
380 return check_pending_signals();
381}
382
383////////////////////////////////////////////////////////////////////////////////
384// signal chaining support
385
386struct sigaction* get_chained_signal_action(int sig) {
387 struct sigaction *actp = NULL__null;
388
389 if (libjsig_is_loaded) {
390 // Retrieve the old signal handler from libjsig
391 actp = (*get_signal_action)(sig);
392 }
393 if (actp == NULL__null) {
394 // Retrieve the preinstalled signal handler from jvm
395 actp = const_cast<struct sigaction*>(chained_handlers.get(sig));
396 }
397
398 return actp;
399}
400
401static bool call_chained_handler(struct sigaction *actp, int sig,
402 siginfo_t *siginfo, void *context) {
403 // Call the old signal handler
404 if (actp->sa_handler__sigaction_handler.sa_handler == SIG_DFL((__sighandler_t) 0)) {
405 // It's more reasonable to let jvm treat it as an unexpected exception
406 // instead of taking the default action.
407 return false;
408 } else if (actp->sa_handler__sigaction_handler.sa_handler != SIG_IGN((__sighandler_t) 1)) {
409 if ((actp->sa_flags & SA_NODEFER0x40000000) == 0) {
410 // automaticlly block the signal
411 sigaddset(&(actp->sa_mask), sig);
412 }
413
414 sa_handler_t hand = NULL__null;
415 sa_sigaction_t sa = NULL__null;
416 bool siginfo_flag_set = (actp->sa_flags & SA_SIGINFO4) != 0;
417 // retrieve the chained handler
418 if (siginfo_flag_set) {
419 sa = actp->sa_sigaction__sigaction_handler.sa_sigaction;
420 } else {
421 hand = actp->sa_handler__sigaction_handler.sa_handler;
422 }
423
424 if ((actp->sa_flags & SA_RESETHAND0x80000000) != 0) {
425 actp->sa_handler__sigaction_handler.sa_handler = SIG_DFL((__sighandler_t) 0);
426 }
427
428 // try to honor the signal mask
429 sigset_t oset;
430 sigemptyset(&oset);
431 pthread_sigmask(SIG_SETMASK2, &(actp->sa_mask), &oset);
432
433 // call into the chained handler
434 if (siginfo_flag_set) {
435 (*sa)(sig, siginfo, context);
436 } else {
437 (*hand)(sig);
438 }
439
440 // restore the signal mask
441 pthread_sigmask(SIG_SETMASK2, &oset, NULL__null);
442 }
443 // Tell jvm's signal handler the signal is taken care of.
444 return true;
445}
446
447bool PosixSignals::chained_handler(int sig, siginfo_t* siginfo, void* context) {
448 bool chained = false;
449 // signal-chaining
450 if (UseSignalChaining) {
451 struct sigaction *actp = get_chained_signal_action(sig);
452 if (actp != NULL__null) {
453 chained = call_chained_handler(actp, sig, siginfo, context);
454 }
455 }
456 return chained;
457}
458
459///// Synchronous (non-deferrable) error signals (ILL, SEGV, FPE, BUS, TRAP):
460
461// These signals are special because they cannot be deferred and, if they
462// happen while delivery is blocked for the receiving thread, will cause UB
463// (in practice typically resulting in sudden process deaths or hangs, see
464// JDK-8252533). So we must take care never to block them when we cannot be
465// absolutely sure they won't happen. In practice, this is always.
466//
467// Relevant Posix quote:
468// "The behavior of a process is undefined after it ignores a SIGFPE, SIGILL,
469// SIGSEGV, or SIGBUS signal that was not generated by kill(), sigqueue(), or
470// raise()."
471//
472// We also include SIGTRAP in that list of never-to-block-signals. While not
473// mentioned by the Posix documentation, in our (SAPs) experience blocking it
474// causes similar problems. Beside, during normal operation - outside of error
475// handling - SIGTRAP may be used for implicit NULL checking, so it makes sense
476// to never block it.
477//
478// We deal with those signals in two ways:
479// - we just never explicitly block them, which includes not accidentally blocking
480// them via sa_mask when establishing signal handlers.
481// - as an additional safety measure, at the entrance of a signal handler, we
482// unblock them explicitly.
483
484static void add_error_signals_to_set(sigset_t* set) {
485 sigaddset(set, SIGILL4);
486 sigaddset(set, SIGBUS7);
487 sigaddset(set, SIGFPE8);
488 sigaddset(set, SIGSEGV11);
489 sigaddset(set, SIGTRAP5);
490}
491
492static void remove_error_signals_from_set(sigset_t* set) {
493 sigdelset(set, SIGILL4);
494 sigdelset(set, SIGBUS7);
495 sigdelset(set, SIGFPE8);
496 sigdelset(set, SIGSEGV11);
497 sigdelset(set, SIGTRAP5);
498}
499
500// Unblock all signals whose delivery cannot be deferred and which, if they happen
501// while delivery is blocked, would cause crashes or hangs (JDK-8252533).
502void PosixSignals::unblock_error_signals() {
503 sigset_t set;
504 sigemptyset(&set);
505 add_error_signals_to_set(&set);
506 ::pthread_sigmask(SIG_UNBLOCK1, &set, NULL__null);
507}
508
509class ErrnoPreserver: public StackObj {
510 const int _saved;
511public:
512 ErrnoPreserver() : _saved(errno(*__errno_location ())) {}
513 ~ErrnoPreserver() { errno(*__errno_location ()) = _saved; }
514};
515
516////////////////////////////////////////////////////////////////////////////////
517// JVM_handle_(linux|aix|bsd)_signal()
518
519// This routine is the shared part of the central hotspot signal handler. It can
520// also be called by a user application, if a user application prefers to do
521// signal handling itself - in that case it needs to pass signals the VM
522// internally uses on to the VM first.
523//
524// The user-defined signal handler must pass unrecognized signals to this
525// routine, and if it returns true (non-zero), then the signal handler must
526// return immediately. If the flag "abort_if_unrecognized" is true, then this
527// routine will never return false (zero), but instead will execute a VM panic
528// routine to kill the process.
529//
530// If this routine returns false, it is OK to call it again. This allows
531// the user-defined signal handler to perform checks either before or after
532// the VM performs its own checks. Naturally, the user code would be making
533// a serious error if it tried to handle an exception (such as a null check
534// or breakpoint) that the VM was generating for its own correct operation.
535//
536// This routine may recognize any of the following kinds of signals:
537// SIGBUS, SIGSEGV, SIGILL, SIGFPE, SIGQUIT, SIGPIPE, SIGXFSZ, SIGUSR1.
538// It should be consulted by handlers for any of those signals.
539//
540// The caller of this routine must pass in the three arguments supplied
541// to the function referred to in the "sa_sigaction" (not the "sa_handler")
542// field of the structure passed to sigaction(). This routine assumes that
543// the sa_flags field passed to sigaction() includes SA_SIGINFO and SA_RESTART.
544//
545// Note that the VM will print warnings if it detects conflicting signal
546// handlers, unless invoked with the option "-XX:+AllowUserSignalHandlers".
547//
548
549#if defined(BSD)
550#define JVM_HANDLE_XXX_SIGNALJVM_handle_linux_signal JVM_handle_bsd_signal
551#elif defined(AIX)
552#define JVM_HANDLE_XXX_SIGNALJVM_handle_linux_signal JVM_handle_aix_signal
553#elif defined(LINUX1)
554#define JVM_HANDLE_XXX_SIGNALJVM_handle_linux_signal JVM_handle_linux_signal
555#else
556#error who are you?
557#endif
558
559extern "C" JNIEXPORT__attribute__((visibility("default")))
560int JVM_HANDLE_XXX_SIGNALJVM_handle_linux_signal(int sig, siginfo_t* info,
561 void* ucVoid, int abort_if_unrecognized)
562{
563 assert(info != NULL && ucVoid != NULL, "sanity")do { if (!(info != __null && ucVoid != __null)) { (*g_assert_poison
) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 563, "assert(" "info != __null && ucVoid != __null"
") failed", "sanity"); ::breakpoint(); } } while (0);
564
565 // Note: it's not uncommon that JNI code uses signal/sigset to install,
566 // then restore certain signal handler (e.g. to temporarily block SIGPIPE,
567 // or have a SIGILL handler when detecting CPU type). When that happens,
568 // this handler might be invoked with junk info/ucVoid. To avoid unnecessary
569 // crash when libjsig is not preloaded, try handle signals that do not require
570 // siginfo/ucontext first.
571
572 // Preserve errno value over signal handler.
573 // (note: RAII ok here, even with JFR thread crash protection, see below).
574 ErrnoPreserver ep;
575
576 // Unblock all synchronous error signals (see JDK-8252533)
577 PosixSignals::unblock_error_signals();
578
579 ucontext_t* const uc = (ucontext_t*) ucVoid;
580 Thread* const t = Thread::current_or_null_safe();
581
582 // Handle JFR thread crash protection.
583 // Note: this may cause us to longjmp away. Do not use any code before this
584 // point which really needs any form of epilogue code running, eg RAII objects.
585 os::ThreadCrashProtection::check_crash_protection(sig, t);
586
587 bool signal_was_handled = false;
588
589 // Handle assertion poison page accesses.
590#ifdef CAN_SHOW_REGISTERS_ON_ASSERT
591 if (!signal_was_handled &&
592 ((sig == SIGSEGV11 || sig == SIGBUS7) && info != NULL__null && info->si_addr_sifields._sigfault.si_addr == g_assert_poison)) {
593 signal_was_handled = handle_assert_poison_fault(ucVoid, info->si_addr_sifields._sigfault.si_addr);
594 }
595#endif
596
597 if (!signal_was_handled) {
598 // Handle SafeFetch access.
599#ifndef ZERO
600 if (uc != NULL__null) {
601 address pc = os::Posix::ucontext_get_pc(uc);
602 if (StubRoutines::is_safefetch_fault(pc)) {
603 os::Posix::ucontext_set_pc(uc, StubRoutines::continuation_for_safefetch_fault(pc));
604 signal_was_handled = true;
605 }
606 }
607#else
608 // See JDK-8076185
609 if (sig == SIGSEGV11 || sig == SIGBUS7) {
610 sigjmp_buf* const pjb = get_jmp_buf_for_continuation();
611 if (pjb) {
612 siglongjmp(*pjb, 1);
613 }
614 }
615#endif // ZERO
616 }
617
618 // Ignore SIGPIPE and SIGXFSZ (4229104, 6499219).
619 if (!signal_was_handled &&
620 (sig == SIGPIPE13 || sig == SIGXFSZ25)) {
621 PosixSignals::chained_handler(sig, info, ucVoid);
622 signal_was_handled = true; // unconditionally.
623 }
624
625 // Call platform dependent signal handler.
626 if (!signal_was_handled) {
627 JavaThread* const jt = (t != NULL__null && t->is_Java_thread()) ? (JavaThread*) t : NULL__null;
628 signal_was_handled = PosixSignals::pd_hotspot_signal_handler(sig, info, uc, jt);
629 }
630
631 // From here on, if the signal had not been handled, it is a fatal error.
632
633 // Give the chained signal handler - should it exist - a shot.
634 if (!signal_was_handled) {
635 signal_was_handled = PosixSignals::chained_handler(sig, info, ucVoid);
636 }
637
638 // Invoke fatal error handling.
639 if (!signal_was_handled && abort_if_unrecognized) {
640 // Extract pc from context for the error handler to display.
641 address pc = NULL__null;
642 if (uc != NULL__null) {
643 // prepare fault pc address for error reporting.
644 if (S390_ONLY(sig == SIGILL || sig == SIGFPE) NOT_S390(false)false) {
645 pc = (address)info->si_addr_sifields._sigfault.si_addr;
646 } else if (ZERO_ONLY(true) NOT_ZERO(false)false) {
647 // Non-arch-specific Zero code does not really know the pc.
648 // This can be alleviated by making arch-specific os::Posix::ucontext_get_pc
649 // available for Zero for known architectures. But for generic Zero
650 // code, it would still remain unknown.
651 pc = NULL__null;
652 } else {
653 pc = os::Posix::ucontext_get_pc(uc);
654 }
655 }
656 // For Zero, we ignore the crash context, because:
657 // a) The crash would be in C++ interpreter code, so context is not really relevant;
658 // b) Generic Zero code would not be able to parse it, so when generic error
659 // reporting code asks e.g. about frames on stack, Zero would experience
660 // a secondary ShouldNotCallThis() crash.
661 VMError::report_and_die(t, sig, pc, info, NOT_ZERO(ucVoid)ucVoid ZERO_ONLY(NULL));
662 // VMError should not return.
663 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 663); ::breakpoint(); } while (0);
664 }
665 return signal_was_handled;
666}
667
668// Entry point for the hotspot signal handler.
669static void javaSignalHandler(int sig, siginfo_t* info, void* ucVoid) {
670 // Do not add any code here!
671 // Only add code to either JVM_HANDLE_XXX_SIGNAL or PosixSignals::pd_hotspot_signal_handler.
672 (void)JVM_HANDLE_XXX_SIGNALJVM_handle_linux_signal(sig, info, ucVoid, true);
673}
674
675static void UserHandler(int sig, void *siginfo, void *context) {
676
677 PosixSignals::unblock_error_signals();
678
679 // Ctrl-C is pressed during error reporting, likely because the error
680 // handler fails to abort. Let VM die immediately.
681 if (sig == SIGINT2 && VMError::is_error_reported()) {
682 os::die();
683 }
684
685 os::signal_notify(sig);
686}
687
688static void print_signal_handler_name(outputStream* os, address handler, char* buf, size_t buflen) {
689 // We demangle, but omit arguments - signal handlers should have always the same prototype.
690 os::print_function_and_library_name(os, handler, buf, buflen,
691 true, // shorten_path
692 true, // demangle
693 true // omit arguments
694 );
695}
696
697// Writes one-line description of a combination of sigaction.sa_flags into a user
698// provided buffer. Returns that buffer.
699static const char* describe_sa_flags(int flags, char* buffer, size_t size) {
700 char* p = buffer;
701 size_t remaining = size;
702 bool first = true;
703 int idx = 0;
704
705 assert(buffer, "invalid argument")do { if (!(buffer)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 705, "assert(" "buffer" ") failed", "invalid argument"); ::
breakpoint(); } } while (0);
706
707 if (size == 0) {
708 return buffer;
709 }
710
711 strncpy(buffer, "none", size);
712
713 const unsigned int unknown_flag = ~(SA_NOCLDSTOP1 |
714 SA_ONSTACK0x08000000 |
715 SA_NOCLDSTOP1 |
716 SA_RESTART0x10000000 |
717 SA_SIGINFO4 |
718 SA_NOCLDWAIT2 |
719 SA_NODEFER0x40000000
720 AIX_ONLY(| SA_OLDSTYLE)
721 );
722
723 const struct {
724 // NB: i is an unsigned int here because SA_RESETHAND is on some
725 // systems 0x80000000, which is implicitly unsigned. Assigning
726 // it to an int field would be an overflow in unsigned-to-signed
727 // conversion.
728 unsigned int i;
729 const char* s;
730 } flaginfo [] = {
731 { SA_NOCLDSTOP1, "SA_NOCLDSTOP" },
732 { SA_ONSTACK0x08000000, "SA_ONSTACK" },
733 { SA_RESETHAND0x80000000, "SA_RESETHAND" },
734 { SA_RESTART0x10000000, "SA_RESTART" },
735 { SA_SIGINFO4, "SA_SIGINFO" },
736 { SA_NOCLDWAIT2, "SA_NOCLDWAIT" },
737 { SA_NODEFER0x40000000, "SA_NODEFER" },
738#if defined(AIX)
739 { SA_OLDSTYLE, "SA_OLDSTYLE" },
740#endif
741 { unknown_flag, "NOT USED" }
742 };
743
744 for (idx = 0; flaginfo[idx].i != unknown_flag && remaining > 1; idx++) {
745 if (flags & flaginfo[idx].i) {
746 if (first) {
747 jio_snprintf(p, remaining, "%s", flaginfo[idx].s);
748 first = false;
749 } else {
750 jio_snprintf(p, remaining, "|%s", flaginfo[idx].s);
751 }
752 const size_t len = strlen(p);
753 p += len;
754 remaining -= len;
755 }
756 }
757 unsigned int unknowns = flags & unknown_flag;
758 if (unknowns != 0) {
759 jio_snprintf(p, remaining, "|Unknown_flags:%x", unknowns);
760 }
761
762 buffer[size - 1] = '\0';
763
764 return buffer;
765}
766
767// Prints one-line description of a combination of sigaction.sa_flags.
768static void print_sa_flags(outputStream* st, int flags) {
769 char buffer[0x100];
770 describe_sa_flags(flags, buffer, sizeof(buffer));
771 st->print("%s", buffer);
772}
773
774// Implementation may use the same storage for both the sa_sigaction field and the sa_handler field,
775// so check for "sigAct.sa_flags == SA_SIGINFO"
776static address get_signal_handler(const struct sigaction* action) {
777 bool siginfo_flag_set = (action->sa_flags & SA_SIGINFO4) != 0;
778 if (siginfo_flag_set) {
779 return CAST_FROM_FN_PTR(address, action->sa_sigaction)((address)((address_word)(action->__sigaction_handler.sa_sigaction
)));
780 } else {
781 return CAST_FROM_FN_PTR(address, action->sa_handler)((address)((address_word)(action->__sigaction_handler.sa_handler
)));
782 }
783}
784
785typedef int (*os_sigaction_t)(int, const struct sigaction *, struct sigaction *);
786
787static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context);
788
789// Semantically compare two sigaction structures. Return true if they are referring to
790// the same handler, using the same flags.
791static bool are_handlers_equal(const struct sigaction* sa,
792 const struct sigaction* expected_sa) {
793 address this_handler = get_signal_handler(sa);
794 address expected_handler = get_signal_handler(expected_sa);
795 const int this_flags = get_sanitized_sa_flags(sa);
796 const int expected_flags = get_sanitized_sa_flags(expected_sa);
797 return (this_handler == expected_handler) &&
798 (this_flags == expected_flags);
799}
800
801// If we installed one of our signal handlers for sig, check that the current
802// setup matches what we originally installed.
803static void check_signal_handler(int sig) {
804 char buf[O_BUFLEN2000];
805 bool mismatch = false;
806
807 if (!do_check_signal_periodically[sig]) {
808 return;
809 }
810
811 const struct sigaction* expected_act = vm_handlers.get(sig);
812 assert(expected_act != NULL, "Sanity")do { if (!(expected_act != __null)) { (*g_assert_poison) = 'X'
;; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 812, "assert(" "expected_act != __null" ") failed", "Sanity"
); ::breakpoint(); } } while (0);
813
814 // Retrieve current signal setup.
815 struct sigaction act;
816 static os_sigaction_t os_sigaction = NULL__null;
817 if (os_sigaction == NULL__null) {
818 // only trust the default sigaction, in case it has been interposed
819 os_sigaction = (os_sigaction_t)dlsym(RTLD_DEFAULT((void *) 0), "sigaction");
820 if (os_sigaction == NULL__null) return;
821 }
822
823 os_sigaction(sig, (struct sigaction*)NULL__null, &act);
824
825 // Compare both sigaction structures (intelligently; only the members we care about).
826 if (!are_handlers_equal(&act, expected_act)) {
827 tty->print_cr("Warning: %s handler modified!", os::exception_name(sig, buf, sizeof(buf)));
828 // If we had a mismatch:
829 // - print all signal handlers. As part of that printout, details will be printed
830 // about any modified handlers.
831 // - Disable any further checks for this signal - we do not want to flood stdout. Though
832 // depending on which signal had been overwritten, we may die very soon anyway.
833 os::print_signal_handlers(tty, buf, O_BUFLEN2000);
834 do_check_signal_periodically[sig] = false;
835 tty->print_cr("Consider using jsig library.");
836 // Running under non-interactive shell, SHUTDOWN2_SIGNAL will be reassigned SIG_IGN
837 if (sig == SHUTDOWN2_SIGNAL2 && !isatty(fileno(stdinstdin))) {
838 tty->print_cr("Note: Running in non-interactive shell, %s handler is replaced by shell",
839 os::exception_name(sig, buf, O_BUFLEN2000));
840 }
841 }
842}
843
844void* os::user_handler() {
845 return CAST_FROM_FN_PTR(void*, UserHandler)((void*)((address_word)(UserHandler)));
846}
847
848void* os::signal(int signal_number, void* handler) {
849 struct sigaction sigAct, oldSigAct;
850
851 sigfillset(&(sigAct.sa_mask));
852 remove_error_signals_from_set(&(sigAct.sa_mask));
853
854 sigAct.sa_flags = SA_RESTART0x10000000|SA_SIGINFO4;
855 sigAct.sa_handler__sigaction_handler.sa_handler = CAST_TO_FN_PTR(sa_handler_t, handler)(reinterpret_cast<sa_handler_t>(handler));
856
857 if (sigaction(signal_number, &sigAct, &oldSigAct)) {
858 // -1 means registration failed
859 return (void *)-1;
860 }
861
862 return get_signal_handler(&oldSigAct);
863}
864
865void os::signal_raise(int signal_number) {
866 ::raise(signal_number);
867}
868
869// Will be modified when max signal is changed to be dynamic
870int os::sigexitnum_pd() {
871 return NSIG(64 + 1);
872}
873
874// This method is a periodic task to check for misbehaving JNI applications
875// under CheckJNI, we can add any periodic checks here
876void os::run_periodic_checks() {
877
878 if (check_signals == false) return;
879
880 // SEGV and BUS if overridden could potentially prevent
881 // generation of hs*.log in the event of a crash, debugging
882 // such a case can be very challenging, so we absolutely
883 // check the following for a good measure:
884 check_signal_handler(SIGSEGV11);
885 check_signal_handler(SIGILL4);
886 check_signal_handler(SIGFPE8);
887 check_signal_handler(SIGBUS7);
888 check_signal_handler(SIGPIPE13);
889 check_signal_handler(SIGXFSZ25);
890 PPC64_ONLY(check_signal_handler(SIGTRAP);)
891
892 // ReduceSignalUsage allows the user to override these handlers
893 // see comments at the very top and jvm_md.h
894 if (!ReduceSignalUsage) {
895 check_signal_handler(SHUTDOWN1_SIGNAL1);
896 check_signal_handler(SHUTDOWN2_SIGNAL2);
897 check_signal_handler(SHUTDOWN3_SIGNAL15);
898 check_signal_handler(BREAK_SIGNAL3);
899 }
900
901 check_signal_handler(PosixSignals::SR_signum);
902}
903
904// Helper function for PosixSignals::print_siginfo_...():
905// return a textual description for signal code.
906struct enum_sigcode_desc_t {
907 const char* s_name;
908 const char* s_desc;
909};
910
911static bool get_signal_code_description(const siginfo_t* si, enum_sigcode_desc_t* out) {
912
913 const struct {
914 int sig; int code; const char* s_code; const char* s_desc;
915 } t1 [] = {
916 { SIGILL4, ILL_ILLOPCILL_ILLOPC, "ILL_ILLOPC", "Illegal opcode." },
917 { SIGILL4, ILL_ILLOPNILL_ILLOPN, "ILL_ILLOPN", "Illegal operand." },
918 { SIGILL4, ILL_ILLADRILL_ILLADR, "ILL_ILLADR", "Illegal addressing mode." },
919 { SIGILL4, ILL_ILLTRPILL_ILLTRP, "ILL_ILLTRP", "Illegal trap." },
920 { SIGILL4, ILL_PRVOPCILL_PRVOPC, "ILL_PRVOPC", "Privileged opcode." },
921 { SIGILL4, ILL_PRVREGILL_PRVREG, "ILL_PRVREG", "Privileged register." },
922 { SIGILL4, ILL_COPROCILL_COPROC, "ILL_COPROC", "Coprocessor error." },
923 { SIGILL4, ILL_BADSTKILL_BADSTK, "ILL_BADSTK", "Internal stack error." },
924#if defined(IA64) && defined(LINUX1)
925 { SIGILL4, ILL_BADIADDR, "ILL_BADIADDR", "Unimplemented instruction address" },
926 { SIGILL4, ILL_BREAK, "ILL_BREAK", "Application Break instruction" },
927#endif
928 { SIGFPE8, FPE_INTDIVFPE_INTDIV, "FPE_INTDIV", "Integer divide by zero." },
929 { SIGFPE8, FPE_INTOVFFPE_INTOVF, "FPE_INTOVF", "Integer overflow." },
930 { SIGFPE8, FPE_FLTDIVFPE_FLTDIV, "FPE_FLTDIV", "Floating-point divide by zero." },
931 { SIGFPE8, FPE_FLTOVFFPE_FLTOVF, "FPE_FLTOVF", "Floating-point overflow." },
932 { SIGFPE8, FPE_FLTUNDFPE_FLTUND, "FPE_FLTUND", "Floating-point underflow." },
933 { SIGFPE8, FPE_FLTRESFPE_FLTRES, "FPE_FLTRES", "Floating-point inexact result." },
934 { SIGFPE8, FPE_FLTINVFPE_FLTINV, "FPE_FLTINV", "Invalid floating-point operation." },
935 { SIGFPE8, FPE_FLTSUBFPE_FLTSUB, "FPE_FLTSUB", "Subscript out of range." },
936 { SIGSEGV11, SEGV_MAPERRSEGV_MAPERR, "SEGV_MAPERR", "Address not mapped to object." },
937 { SIGSEGV11, SEGV_ACCERRSEGV_ACCERR, "SEGV_ACCERR", "Invalid permissions for mapped object." },
938#if defined(AIX)
939 // no explanation found what keyerr would be
940 { SIGSEGV11, SEGV_KEYERR, "SEGV_KEYERR", "key error" },
941#endif
942#if defined(IA64) && !defined(AIX)
943 { SIGSEGV11, SEGV_PSTKOVF, "SEGV_PSTKOVF", "Paragraph stack overflow" },
944#endif
945 { SIGBUS7, BUS_ADRALNBUS_ADRALN, "BUS_ADRALN", "Invalid address alignment." },
946 { SIGBUS7, BUS_ADRERRBUS_ADRERR, "BUS_ADRERR", "Nonexistent physical address." },
947 { SIGBUS7, BUS_OBJERRBUS_OBJERR, "BUS_OBJERR", "Object-specific hardware error." },
948 { SIGTRAP5, TRAP_BRKPTTRAP_BRKPT, "TRAP_BRKPT", "Process breakpoint." },
949 { SIGTRAP5, TRAP_TRACETRAP_TRACE, "TRAP_TRACE", "Process trace trap." },
950 { SIGCHLD17, CLD_EXITEDCLD_EXITED, "CLD_EXITED", "Child has exited." },
951 { SIGCHLD17, CLD_KILLEDCLD_KILLED, "CLD_KILLED", "Child has terminated abnormally and did not create a core file." },
952 { SIGCHLD17, CLD_DUMPEDCLD_DUMPED, "CLD_DUMPED", "Child has terminated abnormally and created a core file." },
953 { SIGCHLD17, CLD_TRAPPEDCLD_TRAPPED, "CLD_TRAPPED", "Traced child has trapped." },
954 { SIGCHLD17, CLD_STOPPEDCLD_STOPPED, "CLD_STOPPED", "Child has stopped." },
955 { SIGCHLD17, CLD_CONTINUEDCLD_CONTINUED,"CLD_CONTINUED","Stopped child has continued." },
956#ifdef SIGPOLL29
957 { SIGPOLL29, POLL_OUTPOLL_OUT, "POLL_OUT", "Output buffers available." },
958 { SIGPOLL29, POLL_MSGPOLL_MSG, "POLL_MSG", "Input message available." },
959 { SIGPOLL29, POLL_ERRPOLL_ERR, "POLL_ERR", "I/O error." },
960 { SIGPOLL29, POLL_PRIPOLL_PRI, "POLL_PRI", "High priority input available." },
961 { SIGPOLL29, POLL_HUPPOLL_HUP, "POLL_HUP", "Device disconnected. [Option End]" },
962#endif
963 { -1, -1, NULL__null, NULL__null }
964 };
965
966 // Codes valid in any signal context.
967 const struct {
968 int code; const char* s_code; const char* s_desc;
969 } t2 [] = {
970 { SI_USERSI_USER, "SI_USER", "Signal sent by kill()." },
971 { SI_QUEUESI_QUEUE, "SI_QUEUE", "Signal sent by the sigqueue()." },
972 { SI_TIMERSI_TIMER, "SI_TIMER", "Signal generated by expiration of a timer set by timer_settime()." },
973 { SI_ASYNCIOSI_ASYNCIO, "SI_ASYNCIO", "Signal generated by completion of an asynchronous I/O request." },
974 { SI_MESGQSI_MESGQ, "SI_MESGQ", "Signal generated by arrival of a message on an empty message queue." },
975 // Linux specific
976#ifdef SI_TKILLSI_TKILL
977 { SI_TKILLSI_TKILL, "SI_TKILL", "Signal sent by tkill (pthread_kill)" },
978#endif
979#ifdef SI_DETHREAD
980 { SI_DETHREAD, "SI_DETHREAD", "Signal sent by execve() killing subsidiary threads" },
981#endif
982#ifdef SI_KERNELSI_KERNEL
983 { SI_KERNELSI_KERNEL, "SI_KERNEL", "Signal sent by kernel." },
984#endif
985#ifdef SI_SIGIOSI_SIGIO
986 { SI_SIGIOSI_SIGIO, "SI_SIGIO", "Signal sent by queued SIGIO" },
987#endif
988
989#if defined(AIX)
990 { SI_UNDEFINED, "SI_UNDEFINED","siginfo contains partial information" },
991 { SI_EMPTY, "SI_EMPTY", "siginfo contains no useful information" },
992#endif
993
994 { -1, NULL__null, NULL__null }
995 };
996
997 const char* s_code = NULL__null;
998 const char* s_desc = NULL__null;
999
1000 for (int i = 0; t1[i].sig != -1; i ++) {
1001 if (t1[i].sig == si->si_signo && t1[i].code == si->si_code) {
1002 s_code = t1[i].s_code;
1003 s_desc = t1[i].s_desc;
1004 break;
1005 }
1006 }
1007
1008 if (s_code == NULL__null) {
1009 for (int i = 0; t2[i].s_code != NULL__null; i ++) {
1010 if (t2[i].code == si->si_code) {
1011 s_code = t2[i].s_code;
1012 s_desc = t2[i].s_desc;
1013 }
1014 }
1015 }
1016
1017 if (s_code == NULL__null) {
1018 out->s_name = "unknown";
1019 out->s_desc = "unknown";
1020 return false;
1021 }
1022
1023 out->s_name = s_code;
1024 out->s_desc = s_desc;
1025
1026 return true;
1027}
1028
1029bool os::signal_sent_by_kill(const void* siginfo) {
1030 const siginfo_t* const si = (const siginfo_t*)siginfo;
1031 return si->si_code == SI_USERSI_USER || si->si_code == SI_QUEUESI_QUEUE
1032#ifdef SI_TKILLSI_TKILL
1033 || si->si_code == SI_TKILLSI_TKILL
1034#endif
1035 ;
1036}
1037
1038// Returns true if signal number is valid.
1039static bool is_valid_signal(int sig) {
1040 // MacOS not really POSIX compliant: sigaddset does not return
1041 // an error for invalid signal numbers. However, MacOS does not
1042 // support real time signals and simply seems to have just 33
1043 // signals with no holes in the signal range.
1044#if defined(__APPLE__)
1045 return sig >= 1 && sig < NSIG(64 + 1);
1046#else
1047 // Use sigaddset to check for signal validity.
1048 sigset_t set;
1049 sigemptyset(&set);
1050 if (sigaddset(&set, sig) == -1 && errno(*__errno_location ()) == EINVAL22) {
1051 return false;
1052 }
1053 return true;
1054#endif
1055}
1056
1057static const char* get_signal_name(int sig, char* out, size_t outlen) {
1058
1059 const char* ret = NULL__null;
1060
1061#ifdef SIGRTMIN(__libc_current_sigrtmin ())
1062 if (sig >= SIGRTMIN(__libc_current_sigrtmin ()) && sig <= SIGRTMAX(__libc_current_sigrtmax ())) {
1063 if (sig == SIGRTMIN(__libc_current_sigrtmin ())) {
1064 ret = "SIGRTMIN";
1065 } else if (sig == SIGRTMAX(__libc_current_sigrtmax ())) {
1066 ret = "SIGRTMAX";
1067 } else {
1068 jio_snprintf(out, outlen, "SIGRTMIN+%d", sig - SIGRTMIN(__libc_current_sigrtmin ()));
1069 return out;
1070 }
1071 }
1072#endif
1073
1074 if (sig > 0) {
1075 for (int idx = 0; g_signal_info[idx].sig != -1; idx ++) {
1076 if (g_signal_info[idx].sig == sig) {
1077 ret = g_signal_info[idx].name;
1078 break;
1079 }
1080 }
1081 }
1082
1083 if (!ret) {
1084 if (!is_valid_signal(sig)) {
1085 ret = "INVALID";
1086 } else {
1087 ret = "UNKNOWN";
1088 }
1089 }
1090
1091 if (out && outlen > 0) {
1092 strncpy(out, ret, outlen);
1093 out[outlen - 1] = '\0';
1094 }
1095 return out;
1096}
1097
1098void os::print_siginfo(outputStream* os, const void* si0) {
1099
1100 const siginfo_t* const si = (const siginfo_t*) si0;
1101
1102 char buf[20];
1103 os->print("siginfo:");
1104
1105 if (!si) {
1106 os->print(" <null>");
1107 return;
1108 }
1109
1110 const int sig = si->si_signo;
1111
1112 os->print(" si_signo: %d (%s)", sig, get_signal_name(sig, buf, sizeof(buf)));
1113
1114 enum_sigcode_desc_t ed;
1115 get_signal_code_description(si, &ed);
1116 os->print(", si_code: %d (%s)", si->si_code, ed.s_name);
1117
1118 if (si->si_errno) {
1119 os->print(", si_errno: %d", si->si_errno);
1120 }
1121
1122 // Output additional information depending on the signal code.
1123
1124 // Note: Many implementations lump si_addr, si_pid, si_uid etc. together as unions,
1125 // so it depends on the context which member to use. For synchronous error signals,
1126 // we print si_addr, unless the signal was sent by another process or thread, in
1127 // which case we print out pid or tid of the sender.
1128 if (os::signal_sent_by_kill(si)) {
1129 const pid_t pid = si->si_pid_sifields._kill.si_pid;
1130 os->print(", si_pid: %ld", (long) pid);
1131 if (IS_VALID_PID(pid)(pid > 0 && pid < 2147483647)) {
1132 const pid_t me = getpid();
1133 if (me == pid) {
1134 os->print(" (current process)");
1135 }
1136 } else {
1137 os->print(" (invalid)");
1138 }
1139 os->print(", si_uid: %ld", (long) si->si_uid_sifields._kill.si_uid);
1140 if (sig == SIGCHLD17) {
1141 os->print(", si_status: %d", si->si_status_sifields._sigchld.si_status);
1142 }
1143 } else if (sig == SIGSEGV11 || sig == SIGBUS7 || sig == SIGILL4 ||
1144 sig == SIGTRAP5 || sig == SIGFPE8) {
1145 os->print(", si_addr: " PTR_FORMAT"0x%016" "l" "x", p2i(si->si_addr_sifields._sigfault.si_addr));
1146#ifdef SIGPOLL29
1147 } else if (sig == SIGPOLL29) {
1148 // siginfo_t.si_band is defined as "long", and it is so in most
1149 // implementations. But SPARC64 glibc has a bug: si_band is "int".
1150 // Cast si_band to "long" to prevent format specifier mismatch.
1151 // See: https://sourceware.org/bugzilla/show_bug.cgi?id=23821
1152 os->print(", si_band: %ld", (long) si->si_band_sifields._sigpoll.si_band);
1153#endif
1154 }
1155}
1156
1157bool os::signal_thread(Thread* thread, int sig, const char* reason) {
1158 OSThread* osthread = thread->osthread();
1159 if (osthread) {
1160 int status = pthread_kill(osthread->pthread_id(), sig);
1161 if (status == 0) {
1162 Events::log(Thread::current(), "sent signal %d to Thread " INTPTR_FORMAT"0x%016" "l" "x" " because %s.",
1163 sig, p2i(thread), reason);
1164 return true;
1165 }
1166 }
1167 return false;
1168}
1169
1170// Returns:
1171// NULL for an invalid signal number
1172// "SIG<num>" for a valid but unknown signal number
1173// signal name otherwise.
1174const char* os::exception_name(int sig, char* buf, size_t size) {
1175 if (!is_valid_signal(sig)) {
1176 return NULL__null;
1177 }
1178 const char* const name = get_signal_name(sig, buf, size);
1179 if (strcmp(name, "UNKNOWN") == 0) {
1180 jio_snprintf(buf, size, "SIG%d", sig);
1181 }
1182 return buf;
1183}
1184
1185int os::get_signal_number(const char* signal_name) {
1186 char tmp[30];
1187 const char* s = signal_name;
1188 if (s[0] != 'S' || s[1] != 'I' || s[2] != 'G') {
1189 jio_snprintf(tmp, sizeof(tmp), "SIG%s", signal_name);
1190 s = tmp;
1191 }
1192 for (int idx = 0; g_signal_info[idx].sig != -1; idx ++) {
1193 if (strcmp(g_signal_info[idx].name, s) == 0) {
1194 return g_signal_info[idx].sig;
1195 }
1196 }
1197 return -1;
1198}
1199
1200void set_signal_handler(int sig) {
1201 // Check for overwrite.
1202 struct sigaction oldAct;
1203 sigaction(sig, (struct sigaction*)NULL__null, &oldAct);
1204
1205 // Query the current signal handler. Needs to be a separate operation
1206 // from installing a new handler since we need to honor AllowUserSignalHandlers.
1207 void* oldhand = get_signal_handler(&oldAct);
1208 if (!HANDLER_IS_IGN_OR_DFL(oldhand)((((oldhand) == ((void*)((address_word)((((__sighandler_t) 1)
)))))) || (((oldhand) == ((void*)((address_word)((((__sighandler_t
) 0)))))))) &&
1209 !HANDLER_IS(oldhand, javaSignalHandler)((oldhand) == ((void*)((address_word)((javaSignalHandler)))))) {
1210 if (AllowUserSignalHandlers) {
1211 // Do not overwrite; user takes responsibility to forward to us.
1212 return;
1213 } else if (UseSignalChaining) {
1214 // save the old handler in jvm
1215 chained_handlers.set(sig, &oldAct);
1216 // libjsig also interposes the sigaction() call below and saves the
1217 // old sigaction on it own.
1218 } else {
1219 fatal("Encountered unexpected pre-existing sigaction handler "do { (*g_assert_poison) = 'X';; report_fatal(INTERNAL_ERROR, "/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1220, "Encountered unexpected pre-existing sigaction handler "
"%#lx for signal %d.", (long)oldhand, sig); ::breakpoint(); }
while (0)
1220 "%#lx for signal %d.", (long)oldhand, sig)do { (*g_assert_poison) = 'X';; report_fatal(INTERNAL_ERROR, "/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1220, "Encountered unexpected pre-existing sigaction handler "
"%#lx for signal %d.", (long)oldhand, sig); ::breakpoint(); }
while (0);
1221 }
1222 }
1223
1224 struct sigaction sigAct;
1225 sigfillset(&(sigAct.sa_mask));
1226 remove_error_signals_from_set(&(sigAct.sa_mask));
1227 sigAct.sa_sigaction__sigaction_handler.sa_sigaction = javaSignalHandler;
1228 sigAct.sa_flags = SA_SIGINFO4|SA_RESTART0x10000000;
1229#if defined(__APPLE__)
1230 // Needed for main thread as XNU (Mac OS X kernel) will only deliver SIGSEGV
1231 // (which starts as SIGBUS) on main thread with faulting address inside "stack+guard pages"
1232 // if the signal handler declares it will handle it on alternate stack.
1233 // Notice we only declare we will handle it on alt stack, but we are not
1234 // actually going to use real alt stack - this is just a workaround.
1235 // Please see ux_exception.c, method catch_mach_exception_raise for details
1236 // link http://www.opensource.apple.com/source/xnu/xnu-2050.18.24/bsd/uxkern/ux_exception.c
1237 if (sig == SIGSEGV11) {
1238 sigAct.sa_flags |= SA_ONSTACK0x08000000;
1239 }
1240#endif
1241
1242 // Save handler setup for later checking
1243 vm_handlers.set(sig, &sigAct);
1244 do_check_signal_periodically[sig] = true;
1245
1246 int ret = sigaction(sig, &sigAct, &oldAct);
1247 assert(ret == 0, "check")do { if (!(ret == 0)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1247, "assert(" "ret == 0" ") failed", "check"); ::breakpoint
(); } } while (0);
1248
1249 void* oldhand2 = get_signal_handler(&oldAct);
1250 assert(oldhand2 == oldhand, "no concurrent signal handler installation")do { if (!(oldhand2 == oldhand)) { (*g_assert_poison) = 'X';;
report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1250, "assert(" "oldhand2 == oldhand" ") failed", "no concurrent signal handler installation"
); ::breakpoint(); } } while (0);
1251}
1252
1253// install signal handlers for signals that HotSpot needs to
1254// handle in order to support Java-level exception handling.
1255void install_signal_handlers() {
1256 // signal-chaining
1257 typedef void (*signal_setting_t)();
1258 signal_setting_t begin_signal_setting = NULL__null;
1259 signal_setting_t end_signal_setting = NULL__null;
1260 begin_signal_setting = CAST_TO_FN_PTR(signal_setting_t,(reinterpret_cast<signal_setting_t>(dlsym(((void *) 0),
"JVM_begin_signal_setting")))
1261 dlsym(RTLD_DEFAULT, "JVM_begin_signal_setting"))(reinterpret_cast<signal_setting_t>(dlsym(((void *) 0),
"JVM_begin_signal_setting")));
1262 if (begin_signal_setting != NULL__null) {
3
←
Assuming 'begin_signal_setting' is equal to NULL
→
4
←
Taking false branch
→
1263 end_signal_setting = CAST_TO_FN_PTR(signal_setting_t,(reinterpret_cast<signal_setting_t>(dlsym(((void *) 0),
"JVM_end_signal_setting")))
1264 dlsym(RTLD_DEFAULT, "JVM_end_signal_setting"))(reinterpret_cast<signal_setting_t>(dlsym(((void *) 0),
"JVM_end_signal_setting")));
1265 get_signal_action = CAST_TO_FN_PTR(get_signal_t,(reinterpret_cast<get_signal_t>(dlsym(((void *) 0), "JVM_get_signal_action"
)))
1266 dlsym(RTLD_DEFAULT, "JVM_get_signal_action"))(reinterpret_cast<get_signal_t>(dlsym(((void *) 0), "JVM_get_signal_action"
)));
1267 libjsig_is_loaded = true;
1268 assert(UseSignalChaining, "should enable signal-chaining")do { if (!(UseSignalChaining)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1268, "assert(" "UseSignalChaining" ") failed", "should enable signal-chaining"
); ::breakpoint(); } } while (0);
1269 }
1270 if (libjsig_is_loaded) {
5
←
Assuming 'libjsig_is_loaded' is false
→
6
←
Taking false branch
→
1271 // Tell libjsig jvm is setting signal handlers
1272 (*begin_signal_setting)();
1273 }
1274
1275 set_signal_handler(SIGSEGV11);
1276 set_signal_handler(SIGPIPE13);
1277 set_signal_handler(SIGBUS7);
1278 set_signal_handler(SIGILL4);
1279 set_signal_handler(SIGFPE8);
1280 PPC64_ONLY(set_signal_handler(SIGTRAP);)
1281 set_signal_handler(SIGXFSZ25);
1282
1283#if defined(__APPLE__)
1284 // lldb (gdb) installs both standard BSD signal handlers, and mach exception
1285 // handlers. By replacing the existing task exception handler, we disable lldb's mach
1286 // exception handling, while leaving the standard BSD signal handlers functional.
1287 //
1288 // EXC_MASK_BAD_ACCESS needed by all architectures for NULL ptr checking
1289 // EXC_MASK_ARITHMETIC needed by all architectures for div by 0 checking
1290 // EXC_MASK_BAD_INSTRUCTION needed by aarch64 to initiate deoptimization
1291 kern_return_t kr;
1292 kr = task_set_exception_ports(mach_task_self(),
1293 EXC_MASK_BAD_ACCESS | EXC_MASK_ARITHMETIC
1294 AARCH64_ONLY(| EXC_MASK_BAD_INSTRUCTION),
1295 MACH_PORT_NULL,
1296 EXCEPTION_STATE_IDENTITY,
1297 MACHINE_THREAD_STATE);
1298
1299 assert(kr == KERN_SUCCESS, "could not set mach task signal handler")do { if (!(kr == KERN_SUCCESS)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1299, "assert(" "kr == KERN_SUCCESS" ") failed", "could not set mach task signal handler"
); ::breakpoint(); } } while (0);
1300#endif
1301
1302 if (libjsig_is_loaded) {
7
←
Assuming 'libjsig_is_loaded' is true
→
8
←
Taking true branch
→
1303 // Tell libjsig jvm finishes setting signal handlers
1304 (*end_signal_setting)();
9
←
Called function pointer is null (null dereference)
1305 }
1306
1307 // We don't activate signal checker if libjsig is in place, we trust ourselves
1308 // and if UserSignalHandler is installed all bets are off.
1309 // Log that signal checking is off only if -verbose:jni is specified.
1310 if (CheckJNICalls) {
1311 if (libjsig_is_loaded) {
1312 log_debug(jni, resolve)(!(LogImpl<(LogTag::_jni), (LogTag::_resolve), (LogTag::__NO_TAG
), (LogTag::__NO_TAG), (LogTag::__NO_TAG), (LogTag::__NO_TAG)
>::is_level(LogLevel::Debug))) ? (void)0 : LogImpl<(LogTag
::_jni), (LogTag::_resolve), (LogTag::__NO_TAG), (LogTag::__NO_TAG
), (LogTag::__NO_TAG), (LogTag::__NO_TAG)>::write<LogLevel
::Debug>("Info: libjsig is activated, all active signal checking is disabled");
1313 check_signals = false;
1314 }
1315 if (AllowUserSignalHandlers) {
1316 log_debug(jni, resolve)(!(LogImpl<(LogTag::_jni), (LogTag::_resolve), (LogTag::__NO_TAG
), (LogTag::__NO_TAG), (LogTag::__NO_TAG), (LogTag::__NO_TAG)
>::is_level(LogLevel::Debug))) ? (void)0 : LogImpl<(LogTag
::_jni), (LogTag::_resolve), (LogTag::__NO_TAG), (LogTag::__NO_TAG
), (LogTag::__NO_TAG), (LogTag::__NO_TAG)>::write<LogLevel
::Debug>("Info: AllowUserSignalHandlers is activated, all active signal checking is disabled");
1317 check_signals = false;
1318 }
1319 }
1320}
1321
1322// Returns one-line short description of a signal set in a user provided buffer.
1323static const char* describe_signal_set_short(const sigset_t* set, char* buffer, size_t buf_size) {
1324 assert(buf_size == (NUM_IMPORTANT_SIGS + 1), "wrong buffer size")do { if (!(buf_size == (32 + 1))) { (*g_assert_poison) = 'X';
; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1324, "assert(" "buf_size == (32 + 1)" ") failed", "wrong buffer size"
); ::breakpoint(); } } while (0);
1325 // Note: for shortness, just print out the first 32. That should
1326 // cover most of the useful ones, apart from realtime signals.
1327 for (int sig = 1; sig <= NUM_IMPORTANT_SIGS32; sig++) {
1328 const int rc = sigismember(set, sig);
1329 if (rc == -1 && errno(*__errno_location ()) == EINVAL22) {
1330 buffer[sig-1] = '?';
1331 } else {
1332 buffer[sig-1] = rc == 0 ? '0' : '1';
1333 }
1334 }
1335 buffer[NUM_IMPORTANT_SIGS32] = 0;
1336 return buffer;
1337}
1338
1339// Prints one-line description of a signal set.
1340static void print_signal_set_short(outputStream* st, const sigset_t* set) {
1341 char buf[NUM_IMPORTANT_SIGS32 + 1];
1342 describe_signal_set_short(set, buf, sizeof(buf));
1343 st->print("%s", buf);
1344}
1345
1346static void print_single_signal_handler(outputStream* st,
1347 const struct sigaction* act,
1348 char* buf, size_t buflen) {
1349
1350 address handler = get_signal_handler(act);
1351 if (HANDLER_IS_DFL(handler)(((handler) == ((void*)((address_word)((((__sighandler_t) 0))
)))))) {
1352 st->print("SIG_DFL");
1353 } else if (HANDLER_IS_IGN(handler)(((handler) == ((void*)((address_word)((((__sighandler_t) 1))
)))))) {
1354 st->print("SIG_IGN");
1355 } else {
1356 print_signal_handler_name(st, handler, buf, buflen);
1357 }
1358
1359 st->print(", mask=");
1360 print_signal_set_short(st, &(act->sa_mask));
1361
1362 st->print(", flags=");
1363 int flags = get_sanitized_sa_flags(act);
1364 print_sa_flags(st, flags);
1365
1366}
1367
1368// Print established signal handler for this signal.
1369// - if this signal handler was installed by us and is chained to a pre-established user handler
1370// it replaced, print that one too.
1371// - otherwise, if this signal handler was installed by us and replaced another handler to which we
1372// are not chained (e.g. if chaining is off), print that one too.
1373void PosixSignals::print_signal_handler(outputStream* st, int sig,
1374 char* buf, size_t buflen) {
1375
1376 st->print("%10s: ", os::exception_name(sig, buf, buflen));
1377
1378 struct sigaction current_act;
1379 sigaction(sig, NULL__null, &current_act);
1380
1381 print_single_signal_handler(st, &current_act, buf, buflen);
1382 st->cr();
1383
1384 // If we expected to see our own hotspot signal handler but found a different one,
1385 // print a warning (unless the handler replacing it is our own crash handler, which can
1386 // happen if this function is called during error reporting).
1387 const struct sigaction* expected_act = vm_handlers.get(sig);
1388 if (expected_act != NULL__null) {
1389 const address current_handler = get_signal_handler(&current_act);
1390 if (!(HANDLER_IS(current_handler, VMError::crash_handler_address)((current_handler) == ((void*)((address_word)((VMError::crash_handler_address
))))))) {
1391 if (!are_handlers_equal(&current_act, expected_act)) {
1392 st->print_cr(" *** Handler was modified!");
1393 st->print (" *** Expected: ");
1394 print_single_signal_handler(st, expected_act, buf, buflen);
1395 st->cr();
1396 }
1397 }
1398 }
1399
1400 // If there is a chained handler waiting behind the current one, print it too.
1401 const struct sigaction* chained_act = get_chained_signal_action(sig);
1402 if (chained_act != NULL__null) {
1403 st->print(" chained to: ");
1404 print_single_signal_handler(st, &current_act, buf, buflen);
1405 st->cr();
1406 }
1407}
1408
1409void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
1410 st->print_cr("Signal Handlers:");
1411 PosixSignals::print_signal_handler(st, SIGSEGV11, buf, buflen);
1412 PosixSignals::print_signal_handler(st, SIGBUS7 , buf, buflen);
1413 PosixSignals::print_signal_handler(st, SIGFPE8 , buf, buflen);
1414 PosixSignals::print_signal_handler(st, SIGPIPE13, buf, buflen);
1415 PosixSignals::print_signal_handler(st, SIGXFSZ25, buf, buflen);
1416 PosixSignals::print_signal_handler(st, SIGILL4 , buf, buflen);
1417 PosixSignals::print_signal_handler(st, PosixSignals::SR_signum, buf, buflen);
1418 PosixSignals::print_signal_handler(st, SHUTDOWN1_SIGNAL1, buf, buflen);
1419 PosixSignals::print_signal_handler(st, SHUTDOWN2_SIGNAL2 , buf, buflen);
1420 PosixSignals::print_signal_handler(st, SHUTDOWN3_SIGNAL15 , buf, buflen);
1421 PosixSignals::print_signal_handler(st, BREAK_SIGNAL3, buf, buflen);
1422#if defined(SIGDANGER)
1423 // We also want to know if someone else adds a SIGDANGER handler because
1424 // that will interfere with OOM killling.
1425 PosixSignals::print_signal_handler(st, SIGDANGER, buf, buflen);
1426#endif
1427#if defined(SIGTRAP5)
1428 PosixSignals::print_signal_handler(st, SIGTRAP5, buf, buflen);
1429#endif
1430}
1431
1432bool PosixSignals::is_sig_ignored(int sig) {
1433 struct sigaction oact;
1434 sigaction(sig, (struct sigaction*)NULL__null, &oact);
1435 if (HANDLER_IS_IGN(get_signal_handler(&oact))(((get_signal_handler(&oact)) == ((void*)((address_word)(
(((__sighandler_t) 1)))))))) {
1436 return true;
1437 } else {
1438 return false;
1439 }
1440}
1441
1442static void signal_sets_init() {
1443 sigemptyset(&preinstalled_sigs);
1444
1445 // Should also have an assertion stating we are still single-threaded.
1446 assert(!signal_sets_initialized, "Already initialized")do { if (!(!signal_sets_initialized)) { (*g_assert_poison) = 'X'
;; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1446, "assert(" "!signal_sets_initialized" ") failed", "Already initialized"
); ::breakpoint(); } } while (0);
1447 // Fill in signals that are necessarily unblocked for all threads in
1448 // the VM. Currently, we unblock the following signals:
1449 // SHUTDOWN{1,2,3}_SIGNAL: for shutdown hooks support (unless over-ridden
1450 // by -Xrs (=ReduceSignalUsage));
1451 // BREAK_SIGNAL which is unblocked only by the VM thread and blocked by all
1452 // other threads. The "ReduceSignalUsage" boolean tells us not to alter
1453 // the dispositions or masks wrt these signals.
1454 // Programs embedding the VM that want to use the above signals for their
1455 // own purposes must, at this time, use the "-Xrs" option to prevent
1456 // interference with shutdown hooks and BREAK_SIGNAL thread dumping.
1457 // (See bug 4345157, and other related bugs).
1458 // In reality, though, unblocking these signals is really a nop, since
1459 // these signals are not blocked by default.
1460 sigemptyset(&unblocked_sigs);
1461 sigaddset(&unblocked_sigs, SIGILL4);
1462 sigaddset(&unblocked_sigs, SIGSEGV11);
1463 sigaddset(&unblocked_sigs, SIGBUS7);
1464 sigaddset(&unblocked_sigs, SIGFPE8);
1465 PPC64_ONLY(sigaddset(&unblocked_sigs, SIGTRAP);)
1466 sigaddset(&unblocked_sigs, PosixSignals::SR_signum);
1467
1468 if (!ReduceSignalUsage) {
1469 if (!PosixSignals::is_sig_ignored(SHUTDOWN1_SIGNAL1)) {
1470 sigaddset(&unblocked_sigs, SHUTDOWN1_SIGNAL1);
1471 }
1472 if (!PosixSignals::is_sig_ignored(SHUTDOWN2_SIGNAL2)) {
1473 sigaddset(&unblocked_sigs, SHUTDOWN2_SIGNAL2);
1474 }
1475 if (!PosixSignals::is_sig_ignored(SHUTDOWN3_SIGNAL15)) {
1476 sigaddset(&unblocked_sigs, SHUTDOWN3_SIGNAL15);
1477 }
1478 }
1479 // Fill in signals that are blocked by all but the VM thread.
1480 sigemptyset(&vm_sigs);
1481 if (!ReduceSignalUsage) {
1482 sigaddset(&vm_sigs, BREAK_SIGNAL3);
1483 }
1484 debug_only(signal_sets_initialized = true)signal_sets_initialized = true;
1485}
1486
1487// These are signals that are unblocked while a thread is running Java.
1488// (For some reason, they get blocked by default.)
1489static sigset_t* unblocked_signals() {
1490 assert(signal_sets_initialized, "Not initialized")do { if (!(signal_sets_initialized)) { (*g_assert_poison) = 'X'
;; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1490, "assert(" "signal_sets_initialized" ") failed", "Not initialized"
); ::breakpoint(); } } while (0);
1491 return &unblocked_sigs;
1492}
1493
1494// These are the signals that are blocked while a (non-VM) thread is
1495// running Java. Only the VM thread handles these signals.
1496static sigset_t* vm_signals() {
1497 assert(signal_sets_initialized, "Not initialized")do { if (!(signal_sets_initialized)) { (*g_assert_poison) = 'X'
;; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1497, "assert(" "signal_sets_initialized" ") failed", "Not initialized"
); ::breakpoint(); } } while (0);
1498 return &vm_sigs;
1499}
1500
1501void PosixSignals::hotspot_sigmask(Thread* thread) {
1502
1503 //Save caller's signal mask before setting VM signal mask
1504 sigset_t caller_sigmask;
1505 pthread_sigmask(SIG_BLOCK0, NULL__null, &caller_sigmask);
1506
1507 OSThread* osthread = thread->osthread();
1508 osthread->set_caller_sigmask(caller_sigmask);
1509
1510 pthread_sigmask(SIG_UNBLOCK1, unblocked_signals(), NULL__null);
1511
1512 if (!ReduceSignalUsage) {
1513 if (thread->is_VM_thread()) {
1514 // Only the VM thread handles BREAK_SIGNAL ...
1515 pthread_sigmask(SIG_UNBLOCK1, vm_signals(), NULL__null);
1516 } else {
1517 // ... all other threads block BREAK_SIGNAL
1518 pthread_sigmask(SIG_BLOCK0, vm_signals(), NULL__null);
1519 }
1520 }
1521}
1522
1523////////////////////////////////////////////////////////////////////////////////
1524// suspend/resume support
1525
1526// The low-level signal-based suspend/resume support is a remnant from the
1527// old VM-suspension that used to be for java-suspension, safepoints etc,
1528// within hotspot. Currently used by JFR's OSThreadSampler
1529//
1530// The remaining code is greatly simplified from the more general suspension
1531// code that used to be used.
1532//
1533// The protocol is quite simple:
1534// - suspend:
1535// - sends a signal to the target thread
1536// - polls the suspend state of the osthread using a yield loop
1537// - target thread signal handler (SR_handler) sets suspend state
1538// and blocks in sigsuspend until continued
1539// - resume:
1540// - sets target osthread state to continue
1541// - sends signal to end the sigsuspend loop in the SR_handler
1542//
1543// Note that resume_clear_context() and suspend_save_context() are needed
1544// by SR_handler(), so that fetch_frame_from_context() works,
1545// which in part is used by:
1546// - Forte Analyzer: AsyncGetCallTrace()
1547// - StackBanging: get_frame_at_stack_banging_point()
1548
1549sigset_t SR_sigset;
1550
1551static void resume_clear_context(OSThread *osthread) {
1552 osthread->set_ucontext(NULL__null);
1553 osthread->set_siginfo(NULL__null);
1554}
1555
1556static void suspend_save_context(OSThread *osthread, siginfo_t* siginfo, ucontext_t* context) {
1557 osthread->set_ucontext(context);
1558 osthread->set_siginfo(siginfo);
1559}
1560
1561// Handler function invoked when a thread's execution is suspended or
1562// resumed. We have to be careful that only async-safe functions are
1563// called here (Note: most pthread functions are not async safe and
1564// should be avoided.)
1565//
1566// Note: sigwait() is a more natural fit than sigsuspend() from an
1567// interface point of view, but sigwait() prevents the signal handler
1568// from being run. libpthread would get very confused by not having
1569// its signal handlers run and prevents sigwait()'s use with the
1570// mutex granting signal.
1571//
1572// Currently only ever called on the VMThread and JavaThreads (PC sampling)
1573//
1574static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
1575
1576 // Save and restore errno to avoid confusing native code with EINTR
1577 // after sigsuspend.
1578 int old_errno = errno(*__errno_location ());
1579
1580 PosixSignals::unblock_error_signals();
1581
1582 Thread* thread = Thread::current_or_null_safe();
1583 assert(thread != NULL, "Missing current thread in SR_handler")do { if (!(thread != __null)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1583, "assert(" "thread != __null" ") failed", "Missing current thread in SR_handler"
); ::breakpoint(); } } while (0);
1584
1585 // On some systems we have seen signal delivery get "stuck" until the signal
1586 // mask is changed as part of thread termination. Check that the current thread
1587 // has not already terminated - else the following assertion
1588 // will fail because the thread is no longer a JavaThread as the ~JavaThread
1589 // destructor has completed.
1590
1591 if (thread->has_terminated()) {
1592 return;
1593 }
1594
1595 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread")do { if (!(thread->is_VM_thread() || thread->is_Java_thread
())) { (*g_assert_poison) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1595, "assert(" "thread->is_VM_thread() || thread->is_Java_thread()"
") failed", "Must be VMThread or JavaThread"); ::breakpoint(
); } } while (0);
1596
1597 OSThread* osthread = thread->osthread();
1598
1599 os::SuspendResume::State current = osthread->sr.state();
1600
1601 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
1602 suspend_save_context(osthread, siginfo, context);
1603
1604 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
1605 os::SuspendResume::State state = osthread->sr.suspended();
1606 if (state == os::SuspendResume::SR_SUSPENDED) {
1607 sigset_t suspend_set; // signals for sigsuspend()
1608 sigemptyset(&suspend_set);
1609
1610 // get current set of blocked signals and unblock resume signal
1611 pthread_sigmask(SIG_BLOCK0, NULL__null, &suspend_set);
1612 sigdelset(&suspend_set, PosixSignals::SR_signum);
1613
1614 sr_semaphore.signal();
1615
1616 // wait here until we are resumed
1617 while (1) {
1618 sigsuspend(&suspend_set);
1619
1620 os::SuspendResume::State result = osthread->sr.running();
1621 if (result == os::SuspendResume::SR_RUNNING) {
1622 // double check AIX doesn't need this!
1623 sr_semaphore.signal();
1624 break;
1625 } else if (result != os::SuspendResume::SR_SUSPENDED) {
1626 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1626); ::breakpoint(); } while (0);
1627 }
1628 }
1629
1630 } else if (state == os::SuspendResume::SR_RUNNING) {
1631 // request was cancelled, continue
1632 } else {
1633 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1633); ::breakpoint(); } while (0);
1634 }
1635
1636 resume_clear_context(osthread);
1637 } else if (current == os::SuspendResume::SR_RUNNING) {
1638 // request was cancelled, continue
1639 } else if (current == os::SuspendResume::SR_WAKEUP_REQUEST) {
1640 // ignore
1641 } else {
1642 // ignore
1643 }
1644
1645 errno(*__errno_location ()) = old_errno;
1646}
1647
1648int SR_initialize() {
1649 struct sigaction act;
1650 char *s;
1651 // Get signal number to use for suspend/resume
1652 if ((s = ::getenv("_JAVA_SR_SIGNUM")) != 0) {
1653 int sig = ::strtol(s, 0, 10);
1654 if (sig > MAX2(SIGSEGV11, SIGBUS7) && // See 4355769.
1655 sig < NSIG(64 + 1)) { // Must be legal signal and fit into sigflags[].
1656 PosixSignals::SR_signum = sig;
1657 } else {
1658 warning("You set _JAVA_SR_SIGNUM=%d. It must be in range [%d, %d]. Using %d instead.",
1659 sig, MAX2(SIGSEGV11, SIGBUS7)+1, NSIG(64 + 1)-1, PosixSignals::SR_signum);
1660 }
1661 }
1662
1663 assert(PosixSignals::SR_signum > SIGSEGV && PosixSignals::SR_signum > SIGBUS,do { if (!(PosixSignals::SR_signum > 11 && PosixSignals
::SR_signum > 7)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1664, "assert(" "PosixSignals::SR_signum > 11 && PosixSignals::SR_signum > 7"
") failed", "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"
); ::breakpoint(); } } while (0)
1664 "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769")do { if (!(PosixSignals::SR_signum > 11 && PosixSignals
::SR_signum > 7)) { (*g_assert_poison) = 'X';; report_vm_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1664, "assert(" "PosixSignals::SR_signum > 11 && PosixSignals::SR_signum > 7"
") failed", "SR_signum must be greater than max(SIGSEGV, SIGBUS), see 4355769"
); ::breakpoint(); } } while (0);
1665
1666 sigemptyset(&SR_sigset);
1667 sigaddset(&SR_sigset, PosixSignals::SR_signum);
1668
1669 // Set up signal handler for suspend/resume
1670 act.sa_flags = SA_RESTART0x10000000|SA_SIGINFO4;
1671 act.sa_handler__sigaction_handler.sa_handler = (void (*)(int)) SR_handler;
1672
1673 // SR_signum is blocked by default.
1674 pthread_sigmask(SIG_BLOCK0, NULL__null, &act.sa_mask);
1675 remove_error_signals_from_set(&(act.sa_mask));
1676
1677 if (sigaction(PosixSignals::SR_signum, &act, 0) == -1) {
1678 return -1;
1679 }
1680
1681 // Save signal setup information for later checking.
1682 vm_handlers.set(PosixSignals::SR_signum, &act);
1683 do_check_signal_periodically[PosixSignals::SR_signum] = true;
1684
1685 return 0;
1686}
1687
1688static int sr_notify(OSThread* osthread) {
1689 int status = pthread_kill(osthread->pthread_id(), PosixSignals::SR_signum);
1690 assert_status(status == 0, status, "pthread_kill")do { if (!(status == 0)) { (*g_assert_poison) = 'X';; report_vm_status_error
("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1690, "assert(" "status == 0" ") failed", status, "pthread_kill"
); ::breakpoint(); } } while (0);
1691 return status;
1692}
1693
1694// returns true on success and false on error - really an error is fatal
1695// but this seems the normal response to library errors
1696bool PosixSignals::do_suspend(OSThread* osthread) {
1697 assert(osthread->sr.is_running(), "thread should be running")do { if (!(osthread->sr.is_running())) { (*g_assert_poison
) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1697, "assert(" "osthread->sr.is_running()" ") failed", "thread should be running"
); ::breakpoint(); } } while (0);
1698 assert(!sr_semaphore.trywait(), "semaphore has invalid state")do { if (!(!sr_semaphore.trywait())) { (*g_assert_poison) = 'X'
;; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1698, "assert(" "!sr_semaphore.trywait()" ") failed", "semaphore has invalid state"
); ::breakpoint(); } } while (0);
1699
1700 // mark as suspended and send signal
1701 if (osthread->sr.request_suspend() != os::SuspendResume::SR_SUSPEND_REQUEST) {
1702 // failed to switch, state wasn't running?
1703 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1703); ::breakpoint(); } while (0);
1704 return false;
1705 }
1706
1707 if (sr_notify(osthread) != 0) {
1708 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1708); ::breakpoint(); } while (0);
1709 }
1710
1711 // managed to send the signal and switch to SUSPEND_REQUEST, now wait for SUSPENDED
1712 while (true) {
1713 if (sr_semaphore.timedwait(2)) {
1714 break;
1715 } else {
1716 // timeout
1717 os::SuspendResume::State cancelled = osthread->sr.cancel_suspend();
1718 if (cancelled == os::SuspendResume::SR_RUNNING) {
1719 return false;
1720 } else if (cancelled == os::SuspendResume::SR_SUSPENDED) {
1721 // make sure that we consume the signal on the semaphore as well
1722 sr_semaphore.wait();
1723 break;
1724 } else {
1725 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1725); ::breakpoint(); } while (0);
1726 return false;
1727 }
1728 }
1729 }
1730
1731 guarantee(osthread->sr.is_suspended(), "Must be suspended")do { if (!(osthread->sr.is_suspended())) { (*g_assert_poison
) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1731, "guarantee(" "osthread->sr.is_suspended()" ") failed"
, "Must be suspended"); ::breakpoint(); } } while (0);
1732 return true;
1733}
1734
1735void PosixSignals::do_resume(OSThread* osthread) {
1736 assert(osthread->sr.is_suspended(), "thread should be suspended")do { if (!(osthread->sr.is_suspended())) { (*g_assert_poison
) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1736, "assert(" "osthread->sr.is_suspended()" ") failed"
, "thread should be suspended"); ::breakpoint(); } } while (0
);
1737 assert(!sr_semaphore.trywait(), "invalid semaphore state")do { if (!(!sr_semaphore.trywait())) { (*g_assert_poison) = 'X'
;; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1737, "assert(" "!sr_semaphore.trywait()" ") failed", "invalid semaphore state"
); ::breakpoint(); } } while (0);
1738
1739 if (osthread->sr.request_wakeup() != os::SuspendResume::SR_WAKEUP_REQUEST) {
1740 // failed to switch to WAKEUP_REQUEST
1741 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1741); ::breakpoint(); } while (0);
1742 return;
1743 }
1744
1745 while (true) {
1746 if (sr_notify(osthread) == 0) {
1747 if (sr_semaphore.timedwait(2)) {
1748 if (osthread->sr.is_running()) {
1749 return;
1750 }
1751 }
1752 } else {
1753 ShouldNotReachHere()do { (*g_assert_poison) = 'X';; report_should_not_reach_here(
"/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1753); ::breakpoint(); } while (0);
1754 }
1755 }
1756
1757 guarantee(osthread->sr.is_running(), "Must be running!")do { if (!(osthread->sr.is_running())) { (*g_assert_poison
) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/os/posix/signals_posix.cpp"
, 1757, "guarantee(" "osthread->sr.is_running()" ") failed"
, "Must be running!"); ::breakpoint(); } } while (0);
1758}
1759
1760void os::SuspendedThreadTask::internal_do_task() {
1761 if (PosixSignals::do_suspend(_thread->osthread())) {
1762 os::SuspendedThreadTaskContext context(_thread, _thread->osthread()->ucontext());
1763 do_task(context);
1764 PosixSignals::do_resume(_thread->osthread());
1765 }
1766}
1767
1768int PosixSignals::init() {
1769 // initialize suspend/resume support - must do this before signal_sets_init()
1770 if (SR_initialize() != 0) {
1
Taking false branch
→
1771 vm_exit_during_initialization("SR_initialize failed");
1772 return JNI_ERR(-1);
1773 }
1774
1775 signal_sets_init();
1776
1777 install_signal_handlers();
2
←
Calling 'install_signal_handlers'
→
1778
1779 // Initialize data for jdk.internal.misc.Signal
1780 if (!ReduceSignalUsage) {
1781 jdk_misc_signal_init();
1782 }
1783
1784 return JNI_OK0;
1785}