/*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
// This is heavily inspired by the signal handler from google-glog
-#include "folly/experimental/symbolizer/SignalHandler.h"
+#include <folly/experimental/symbolizer/SignalHandler.h>
+#include <pthread.h>
+#include <signal.h>
#include <sys/types.h>
+#include <unistd.h>
+
+#include <algorithm>
#include <atomic>
#include <ctime>
#include <mutex>
-#include <pthread.h>
-#include <signal.h>
-#include <unistd.h>
#include <vector>
#include <glog/logging.h>
-#include "folly/Conv.h"
-#include "folly/FileUtil.h"
-#include "folly/Portability.h"
-#include "folly/ScopeGuard.h"
-#include "folly/experimental/symbolizer/Symbolizer.h"
+#include <folly/Conv.h>
+#include <folly/FileUtil.h>
+#include <folly/Portability.h>
+#include <folly/ScopeGuard.h>
+#include <folly/experimental/symbolizer/ElfCache.h>
+#include <folly/experimental/symbolizer/Symbolizer.h>
+#include <folly/portability/SysSyscall.h>
namespace folly { namespace symbolizer {
void FatalSignalCallbackRegistry::run() {
if (!installed_) {
- return; // Shouldn't happen
+ return;
}
for (auto& fn : handlers_) {
const char* name;
struct sigaction oldAction;
} kFatalSignals[] = {
- { SIGSEGV, "SIGSEGV" },
- { SIGILL, "SIGILL" },
- { SIGFPE, "SIGFPE" },
- { SIGABRT, "SIGABRT" },
- { SIGBUS, "SIGBUS" },
- { SIGTERM, "SIGTERM" },
- { 0, nullptr }
+ { SIGSEGV, "SIGSEGV", {} },
+ { SIGILL, "SIGILL", {} },
+ { SIGFPE, "SIGFPE", {} },
+ { SIGABRT, "SIGABRT", {} },
+ { SIGBUS, "SIGBUS", {} },
+ { SIGTERM, "SIGTERM", {} },
+ { 0, nullptr, {} }
};
void callPreviousSignalHandler(int signum) {
for (auto p = kFatalSignals; p->name; ++p) {
if (p->number == signum) {
sigaction(signum, &p->oldAction, nullptr);
+ raise(signum);
return;
}
}
raise(signum);
}
+// Note: not thread-safe, but that's okay, as we only let one thread
+// in our signal handler at a time.
+//
+// Leak it so we don't have to worry about destruction order
+constexpr size_t kMinSignalSafeElfCacheSize = 500;
+auto gSignalSafeElfCache = new SignalSafeElfCache(
+ std::max(countLoadedElfFiles(), kMinSignalSafeElfCacheSize));
+
+// Buffered writer (using a fixed-size buffer). We try to write only once
+// to prevent interleaving with messages written from other threads.
+//
+// Leak it so we don't have to worry about destruction order.
+auto gPrinter = new FDSymbolizePrinter(STDERR_FILENO,
+ SymbolizePrinter::COLOR_IF_TTY,
+ size_t(64) << 10); // 64KiB
+
+// Flush gPrinter, also fsync, in case we're about to crash again...
+void flush() {
+ gPrinter->flush();
+ fsyncNoInt(STDERR_FILENO);
+}
+
void printDec(uint64_t val) {
char buf[20];
uint32_t n = uint64ToBufferUnsafe(val, buf);
- writeFull(STDERR_FILENO, buf, n);
+ gPrinter->print(StringPiece(buf, n));
}
const char kHexChars[] = "0123456789abcdef";
*--p = 'x';
*--p = '0';
- writeFull(STDERR_FILENO, p, end - p);
+ gPrinter->print(StringPiece(p, end));
}
void print(StringPiece sp) {
- writeFull(STDERR_FILENO, sp.data(), sp.size());
+ gPrinter->print(sp);
}
void dumpTimeInfo() {
- SCOPE_EXIT { fsyncNoInt(STDERR_FILENO); };
+ SCOPE_EXIT { flush(); };
time_t now = time(nullptr);
print("*** Aborted at ");
printDec(now);
print("') ***\n");
}
+const char* sigill_reason(int si_code) {
+ switch (si_code) {
+ case ILL_ILLOPC:
+ return "illegal opcode";
+ case ILL_ILLOPN:
+ return "illegal operand";
+ case ILL_ILLADR:
+ return "illegal addressing mode";
+ case ILL_ILLTRP:
+ return "illegal trap";
+ case ILL_PRVOPC:
+ return "privileged opcode";
+ case ILL_PRVREG:
+ return "privileged register";
+ case ILL_COPROC:
+ return "coprocessor error";
+ case ILL_BADSTK:
+ return "internal stack error";
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* sigfpe_reason(int si_code) {
+ switch (si_code) {
+ case FPE_INTDIV:
+ return "integer divide by zero";
+ case FPE_INTOVF:
+ return "integer overflow";
+ case FPE_FLTDIV:
+ return "floating-point divide by zero";
+ case FPE_FLTOVF:
+ return "floating-point overflow";
+ case FPE_FLTUND:
+ return "floating-point underflow";
+ case FPE_FLTRES:
+ return "floating-point inexact result";
+ case FPE_FLTINV:
+ return "floating-point invalid operation";
+ case FPE_FLTSUB:
+ return "subscript out of range";
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* sigsegv_reason(int si_code) {
+ switch (si_code) {
+ case SEGV_MAPERR:
+ return "address not mapped to object";
+ case SEGV_ACCERR:
+ return "invalid permissions for mapped object";
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* sigbus_reason(int si_code) {
+ switch (si_code) {
+ case BUS_ADRALN:
+ return "invalid address alignment";
+ case BUS_ADRERR:
+ return "nonexistent physical address";
+ case BUS_OBJERR:
+ return "object-specific hardware error";
+
+ // MCEERR_AR and MCEERR_AO: in sigaction(2) but not in headers.
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* sigtrap_reason(int si_code) {
+ switch (si_code) {
+ case TRAP_BRKPT:
+ return "process breakpoint";
+ case TRAP_TRACE:
+ return "process trace trap";
+
+ // TRAP_BRANCH and TRAP_HWBKPT: in sigaction(2) but not in headers.
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* sigchld_reason(int si_code) {
+ switch (si_code) {
+ case CLD_EXITED:
+ return "child has exited";
+ case CLD_KILLED:
+ return "child was killed";
+ case CLD_DUMPED:
+ return "child terminated abnormally";
+ case CLD_TRAPPED:
+ return "traced child has trapped";
+ case CLD_STOPPED:
+ return "child has stopped";
+ case CLD_CONTINUED:
+ return "stopped child has continued";
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* sigio_reason(int si_code) {
+ switch (si_code) {
+ case POLL_IN:
+ return "data input available";
+ case POLL_OUT:
+ return "output buffers available";
+ case POLL_MSG:
+ return "input message available";
+ case POLL_ERR:
+ return "I/O error";
+ case POLL_PRI:
+ return "high priority input available";
+ case POLL_HUP:
+ return "device disconnected";
+
+ default:
+ return nullptr;
+ }
+}
+
+const char* signal_reason(int signum, int si_code) {
+ switch (signum) {
+ case SIGILL:
+ return sigill_reason(si_code);
+ case SIGFPE:
+ return sigfpe_reason(si_code);
+ case SIGSEGV:
+ return sigsegv_reason(si_code);
+ case SIGBUS:
+ return sigbus_reason(si_code);
+ case SIGTRAP:
+ return sigtrap_reason(si_code);
+ case SIGCHLD:
+ return sigchld_reason(si_code);
+ case SIGIO:
+ return sigio_reason(si_code); // aka SIGPOLL
+
+ default:
+ return nullptr;
+ }
+}
+
void dumpSignalInfo(int signum, siginfo_t* siginfo) {
- SCOPE_EXIT { fsyncNoInt(STDERR_FILENO); };
+ SCOPE_EXIT { flush(); };
// Get the signal name, if possible.
const char* name = nullptr;
for (auto p = kFatalSignals; p->name; ++p) {
printHex(reinterpret_cast<uint64_t>(siginfo->si_addr));
print(") received by PID ");
printDec(getpid());
- print(" (TID ");
+ print(" (pthread TID ");
printHex((uint64_t)pthread_self());
+ print(") (linux TID ");
+ printDec(syscall(__NR_gettid));
+
+ // Kernel-sourced signals don't give us useful info for pid/uid.
+ if (siginfo->si_code != SI_KERNEL) {
+ print(") (maybe from PID ");
+ printDec(siginfo->si_pid);
+ print(", UID ");
+ printDec(siginfo->si_uid);
+ }
+
+ auto reason = signal_reason(signum, siginfo->si_code);
+
+ if (reason != nullptr) {
+ print(") (code: ");
+ print(reason);
+ }
+
print("), stack trace: ***\n");
}
-void dumpStackTrace() {
- SCOPE_EXIT { fsyncNoInt(STDERR_FILENO); };
+FOLLY_NOINLINE void dumpStackTrace(bool symbolize);
+
+void dumpStackTrace(bool symbolize) {
+ SCOPE_EXIT { flush(); };
// Get and symbolize stack trace
constexpr size_t kMaxStackTraceDepth = 100;
FrameArray<kMaxStackTraceDepth> addresses;
// Skip the getStackTrace frame
- if (!getStackTrace(addresses)) {
+ if (!getStackTraceSafe(addresses)) {
print("(error retrieving stack trace)\n");
- } else {
- Symbolizer symbolizer;
+ } else if (symbolize) {
+ // Do our best to populate location info, process is going to terminate,
+ // so performance isn't critical.
+ Symbolizer symbolizer(gSignalSafeElfCache, Dwarf::LocationInfoMode::FULL);
symbolizer.symbolize(addresses);
- FDSymbolizePrinter printer(STDERR_FILENO);
- printer.println(addresses);
+ // Skip the top 2 frames:
+ // getStackTraceSafe
+ // dumpStackTrace (here)
+ //
+ // Leaving signalHandler on the stack for clarity, I think.
+ gPrinter->println(addresses, 2);
+ } else {
+ print("(safe mode, symbolizer not available)\n");
+ AddressFormatter formatter;
+ for (size_t i = 0; i < addresses.frameCount; ++i) {
+ print(formatter.format(addresses.addresses[i]));
+ print("\n");
+ }
}
}
-std::atomic<pthread_t*> gSignalThread;
+// On Linux, pthread_t is a pointer, so 0 is an invalid value, which we
+// take to indicate "no thread in the signal handler".
+//
+// POSIX defines PTHREAD_NULL for this purpose, but that's not available.
+constexpr pthread_t kInvalidThreadId = 0;
+
+std::atomic<pthread_t> gSignalThread(kInvalidThreadId);
+std::atomic<bool> gInRecursiveSignalHandler(false);
// Here be dragons.
-void innerSignalHandler(int signum, siginfo_t* info, void* uctx) {
+void innerSignalHandler(int signum, siginfo_t* info, void* /* uctx */) {
// First, let's only let one thread in here at a time.
pthread_t myId = pthread_self();
- pthread_t* prevSignalThread = nullptr;
- while (!gSignalThread.compare_exchange_strong(prevSignalThread, &myId)) {
- if (pthread_equal(*prevSignalThread, myId)) {
- print("Entered fatal signal handler recursively. We're in trouble.\n");
+ pthread_t prevSignalThread = kInvalidThreadId;
+ while (!gSignalThread.compare_exchange_strong(prevSignalThread, myId)) {
+ if (pthread_equal(prevSignalThread, myId)) {
+ // First time here. Try to dump the stack trace without symbolization.
+ // If we still fail, well, we're mightily screwed, so we do nothing the
+ // next time around.
+ if (!gInRecursiveSignalHandler.exchange(true)) {
+ print("Entered fatal signal handler recursively. We're in trouble.\n");
+ dumpStackTrace(false); // no symbolization
+ }
return;
}
ts.tv_nsec = 100L * 1000 * 1000; // 100ms
nanosleep(&ts, nullptr);
- prevSignalThread = nullptr;
+ prevSignalThread = kInvalidThreadId;
}
dumpTimeInfo();
dumpSignalInfo(signum, info);
- dumpStackTrace();
+ dumpStackTrace(true); // with symbolization
// Run user callbacks
gFatalSignalCallbackRegistry->run();
}
void signalHandler(int signum, siginfo_t* info, void* uctx) {
- SCOPE_EXIT { fsyncNoInt(STDERR_FILENO); };
+ SCOPE_EXIT { flush(); };
innerSignalHandler(signum, info, uctx);
- gSignalThread = nullptr;
+ gSignalThread = kInvalidThreadId;
// Kill ourselves with the previous handler.
callPreviousSignalHandler(signum);
}
gFatalSignalCallbackRegistry->add(cb);
}
+void installFatalSignalCallbacks() {
+ gFatalSignalCallbackRegistry->markInstalled();
+}
+
namespace {
std::atomic<bool> gAlreadyInstalled;
return;
}
- gFatalSignalCallbackRegistry->markInstalled();
-
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
- sa.sa_flags |= SA_SIGINFO;
+ // By default signal handlers are run on the signaled thread's stack.
+ // In case of stack overflow running the SIGSEGV signal handler on
+ // the same stack leads to another SIGSEGV and crashes the program.
+ // Use SA_ONSTACK, so alternate stack is used (only if configured via
+ // sigaltstack).
+ sa.sa_flags |= SA_SIGINFO | SA_ONSTACK;
sa.sa_sigaction = &signalHandler;
for (auto p = kFatalSignals; p->name; ++p) {
}
}} // namespaces
-
projects / folly.git / blobdiff