nsSigHandlers.cpp
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* This module is supposed to abstract signal handling away from the other
* platforms that do not support it.
*/
#include "nsSigHandlers.h"
#ifdef XP_UNIX
# include <signal.h>
# include <stdio.h>
# include <string.h>
# include "prthread.h"
# include "prenv.h"
# include "nsDebug.h"
# include "nsString.h"
# include "nsXULAppAPI.h"
# if defined(LINUX)
# include <sys/time.h>
# include <sys/resource.h>
# include <unistd.h>
# include <stdlib.h> // atoi
# include <sys/prctl.h>
# ifndef ANDROID // no Android impl
# include <ucontext.h>
# endif
# endif
# if defined(SOLARIS)
# include <sys/resource.h>
# include <ucontext.h>
# endif
// Note: some tests manipulate this value.
unsigned int _gdb_sleep_duration = 300;
# if defined(LINUX) && !defined(ANDROID) && defined(DEBUG) && \
(defined(__i386) || defined(__x86_64) || defined(PPC))
# define CRAWL_STACK_ON_SIGSEGV
# endif
# ifndef PR_SET_PTRACER
# define PR_SET_PTRACER 0x59616d61
# endif
# ifndef PR_SET_PTRACER_ANY
# define PR_SET_PTRACER_ANY ((unsigned long)-1)
# endif
# if defined(CRAWL_STACK_ON_SIGSEGV)
# include <unistd.h>
# include "nsISupportsUtils.h"
# include "mozilla/Attributes.h"
# include "mozilla/StackWalk.h"
static const char* gProgname = "huh?";
// NB: keep me up to date with the same variable in
// ipc/chromium/chrome/common/ipc_channel_posix.cc
static const int kClientChannelFd = 3;
extern "C" {
static void PrintStackFrame(uint32_t aFrameNumber, void* aPC, void* aSP,
void* aClosure) {
char buf[1024];
MozCodeAddressDetails details;
MozDescribeCodeAddress(aPC, &details);
MozFormatCodeAddressDetails(buf, sizeof(buf), aFrameNumber, aPC, &details);
fprintf(stdout, "%s\n", buf);
fflush(stdout);
}
}
void common_crap_handler(int signum, const void* aFirstFramePC) {
printf("\nProgram %s (pid = %d) received signal %d.\n", gProgname, getpid(),
signum);
printf("Stack:\n");
MozStackWalk(PrintStackFrame, aFirstFramePC, /* maxFrames */ 0, nullptr);
printf("Sleeping for %d seconds.\n", _gdb_sleep_duration);
printf("Type 'gdb %s %d' to attach your debugger to this thread.\n",
gProgname, getpid());
// Allow us to be ptraced by gdb on Linux with Yama restrictions enabled.
prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
sleep(_gdb_sleep_duration);
printf("Done sleeping...\n");
_exit(signum);
}
MOZ_NEVER_INLINE void ah_crap_handler(int signum) {
common_crap_handler(signum, CallerPC());
}
MOZ_NEVER_INLINE void child_ah_crap_handler(int signum) {
if (!getenv("MOZ_DONT_UNBLOCK_PARENT_ON_CHILD_CRASH"))
close(kClientChannelFd);
common_crap_handler(signum, CallerPC());
}
# endif // CRAWL_STACK_ON_SIGSEGV
# ifdef MOZ_WIDGET_GTK
// Need this include for version test below.
# include <glib.h>
# endif
# if defined(MOZ_WIDGET_GTK) && \
(GLIB_MAJOR_VERSION > 2 || \
(GLIB_MAJOR_VERSION == 2 && GLIB_MINOR_VERSION >= 6))
static GLogFunc orig_log_func = nullptr;
extern "C" {
static void glib_log_func(const gchar* log_domain, GLogLevelFlags log_level,
const gchar* message, gpointer user_data);
}
// GDK sometimes avoids calling exit handlers, but we still want to know when we
// crash, see https://gitlab.gnome.org/GNOME/gtk/-/issues/4514 and bug 1743144.
static bool IsCrashyGtkMessage(const nsACString& aMessage) {
if (aMessage.EqualsLiteral("Lost connection to Wayland compositor.")) {
// https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L210
return true;
}
if (StringBeginsWith(aMessage, "Error flushing display: "_ns)) {
// https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L68
return true;
}
if (StringBeginsWith(aMessage, "Error reading events from display: "_ns)) {
// https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L97
return true;
}
if (StringBeginsWith(aMessage, "Error "_ns) &&
StringEndsWith(aMessage, " dispatching to Wayland display."_ns)) {
// https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L205
return true;
}
return false;
}
/* static */ void glib_log_func(const gchar* log_domain,
GLogLevelFlags log_level, const gchar* message,
gpointer user_data) {
if (MOZ_UNLIKELY(IsCrashyGtkMessage(nsDependentCString(message)))) {
MOZ_CRASH_UNSAFE(strdup(message));
}
if (log_level &
(G_LOG_LEVEL_ERROR | G_LOG_FLAG_FATAL | G_LOG_FLAG_RECURSION)) {
NS_DebugBreak(NS_DEBUG_ASSERTION, message, "glib assertion", __FILE__,
__LINE__);
} else if (log_level & (G_LOG_LEVEL_CRITICAL | G_LOG_LEVEL_WARNING)) {
NS_DebugBreak(NS_DEBUG_WARNING, message, "glib warning", __FILE__,
__LINE__);
}
orig_log_func(log_domain, log_level, message, nullptr);
}
# endif
# ifdef SA_SIGINFO
static void fpehandler(int signum, siginfo_t* si, void* context) {
/* Integer divide by zero or integer overflow. */
/* Note: FPE_INTOVF is ignored on Intel, PowerPC and SPARC systems. */
if (si->si_code == FPE_INTDIV || si->si_code == FPE_INTOVF) {
NS_DebugBreak(NS_DEBUG_ABORT, "Divide by zero", nullptr, __FILE__,
__LINE__);
}
# ifdef XP_MACOSX
# if defined(__i386__) || defined(__amd64__)
ucontext_t* uc = (ucontext_t*)context;
_STRUCT_FP_CONTROL* ctrl = &uc->uc_mcontext->__fs.__fpu_fcw;
ctrl->__invalid = ctrl->__denorm = ctrl->__zdiv = ctrl->__ovrfl =
ctrl->__undfl = ctrl->__precis = 1;
_STRUCT_FP_STATUS* status = &uc->uc_mcontext->__fs.__fpu_fsw;
status->__invalid = status->__denorm = status->__zdiv = status->__ovrfl =
status->__undfl = status->__precis = status->__stkflt =
status->__errsumm = 0;
uint32_t* mxcsr = &uc->uc_mcontext->__fs.__fpu_mxcsr;
*mxcsr |= SSE_EXCEPTION_MASK; /* disable all SSE exceptions */
*mxcsr &= ~SSE_STATUS_FLAGS; /* clear all pending SSE exceptions */
# endif
# endif
# if defined(LINUX) && !defined(ANDROID)
# if defined(__i386__)
ucontext_t* uc = (ucontext_t*)context;
/*
* It seems that we have no access to mxcsr on Linux. libc
* seems to be translating cw/sw to mxcsr.
*/
unsigned long int* cw = &uc->uc_mcontext.fpregs->cw;
*cw |= FPU_EXCEPTION_MASK;
unsigned long int* sw = &uc->uc_mcontext.fpregs->sw;
*sw &= ~FPU_STATUS_FLAGS;
# endif
# if defined(__amd64__)
ucontext_t* uc = (ucontext_t*)context;
uint16_t* cw = &uc->uc_mcontext.fpregs->cwd;
*cw |= FPU_EXCEPTION_MASK;
uint16_t* sw = &uc->uc_mcontext.fpregs->swd;
*sw &= ~FPU_STATUS_FLAGS;
uint32_t* mxcsr = &uc->uc_mcontext.fpregs->mxcsr;
*mxcsr |= SSE_EXCEPTION_MASK; /* disable all SSE exceptions */
*mxcsr &= ~SSE_STATUS_FLAGS; /* clear all pending SSE exceptions */
# endif
# endif
# ifdef SOLARIS
ucontext_t* uc = (ucontext_t*)context;
# if defined(__i386)
uint32_t* cw = &uc->uc_mcontext.fpregs.fp_reg_set.fpchip_state.state[0];
*cw |= FPU_EXCEPTION_MASK;
uint32_t* sw = &uc->uc_mcontext.fpregs.fp_reg_set.fpchip_state.state[1];
*sw &= ~FPU_STATUS_FLAGS;
/* address of the instruction that caused the exception */
uint32_t* ip = &uc->uc_mcontext.fpregs.fp_reg_set.fpchip_state.state[3];
uc->uc_mcontext.gregs[REG_PC] = *ip;
# endif
# if defined(__amd64__)
uint16_t* cw = &uc->uc_mcontext.fpregs.fp_reg_set.fpchip_state.cw;
*cw |= FPU_EXCEPTION_MASK;
uint16_t* sw = &uc->uc_mcontext.fpregs.fp_reg_set.fpchip_state.sw;
*sw &= ~FPU_STATUS_FLAGS;
uint32_t* mxcsr = &uc->uc_mcontext.fpregs.fp_reg_set.fpchip_state.mxcsr;
*mxcsr |= SSE_EXCEPTION_MASK; /* disable all SSE exceptions */
*mxcsr &= ~SSE_STATUS_FLAGS; /* clear all pending SSE exceptions */
# endif
# endif
}
# endif
void InstallSignalHandlers(const char* aProgname) {
# if defined(CRAWL_STACK_ON_SIGSEGV)
if (aProgname) {
const char* tmp = strdup(aProgname);
if (tmp) {
gProgname = tmp;
}
}
# endif // CRAWL_STACK_ON_SIGSEGV
const char* gdbSleep = PR_GetEnv("MOZ_GDB_SLEEP");
if (gdbSleep && *gdbSleep) {
unsigned int s;
if (1 == sscanf(gdbSleep, "%u", &s)) {
_gdb_sleep_duration = s;
}
}
# if defined(CRAWL_STACK_ON_SIGSEGV)
if (!getenv("XRE_NO_WINDOWS_CRASH_DIALOG")) {
void (*crap_handler)(int) = GeckoProcessType_Default != XRE_GetProcessType()
? child_ah_crap_handler
: ah_crap_handler;
signal(SIGSEGV, crap_handler);
signal(SIGILL, crap_handler);
signal(SIGABRT, crap_handler);
}
# endif // CRAWL_STACK_ON_SIGSEGV
# ifdef SA_SIGINFO
/* Install a handler for floating point exceptions and disable them if they
* occur. */
struct sigaction sa, osa;
sa.sa_flags = SA_ONSTACK | SA_RESTART | SA_SIGINFO;
sa.sa_sigaction = fpehandler;
sigemptyset(&sa.sa_mask);
sigaction(SIGFPE, &sa, &osa);
# endif
if (!XRE_IsParentProcess()) {
/*
* If the user is debugging a Gecko parent process in gdb and hits ^C to
* suspend, a SIGINT signal will be sent to the child. We ignore this signal
* so the child isn't killed.
*/
signal(SIGINT, SIG_IGN);
}
# if defined(DEBUG) && defined(LINUX)
const char* memLimit = PR_GetEnv("MOZ_MEM_LIMIT");
if (memLimit && *memLimit) {
long m = atoi(memLimit);
m *= (1024 * 1024);
struct rlimit r;
r.rlim_cur = m;
r.rlim_max = m;
setrlimit(RLIMIT_AS, &r);
}
# endif
# if defined(MOZ_WIDGET_GTK) && \
(GLIB_MAJOR_VERSION > 2 || \
(GLIB_MAJOR_VERSION == 2 && GLIB_MINOR_VERSION >= 6))
// Override the default glib logging function to intercept some crashes that
// are uninterceptable otherwise.
// Also, when XPCOM_DEBUG_BREAK is set, we can also get stacks for them.
// so we get stacks for it too.
orig_log_func = g_log_set_default_handler(glib_log_func, nullptr);
# endif
}
#elif XP_WIN
# include <windows.h>
# ifdef _M_IX86
/*
* WinNT.h prior to SDK7 does not expose the structure of the ExtendedRegisters
* for ia86. We known that MxCsr is at offset 0x18 and is a DWORD.
*/
# define MXCSR(ctx) (*(DWORD*)(((BYTE*)(ctx)->ExtendedRegisters) + 0x18))
# endif
# ifdef _M_X64
# define MXCSR(ctx) (ctx)->MxCsr
# endif
# if defined(_M_IX86) || defined(_M_X64)
# ifdef _M_X64
# define X87CW(ctx) (ctx)->FltSave.ControlWord
# define X87SW(ctx) (ctx)->FltSave.StatusWord
# else
# define X87CW(ctx) (ctx)->FloatSave.ControlWord
# define X87SW(ctx) (ctx)->FloatSave.StatusWord
# endif
static LPTOP_LEVEL_EXCEPTION_FILTER gFPEPreviousFilter;
LONG __stdcall FpeHandler(PEXCEPTION_POINTERS pe) {
PEXCEPTION_RECORD e = (PEXCEPTION_RECORD)pe->ExceptionRecord;
CONTEXT* c = (CONTEXT*)pe->ContextRecord;
switch (e->ExceptionCode) {
case STATUS_FLOAT_DENORMAL_OPERAND:
case STATUS_FLOAT_DIVIDE_BY_ZERO:
case STATUS_FLOAT_INEXACT_RESULT:
case STATUS_FLOAT_INVALID_OPERATION:
case STATUS_FLOAT_OVERFLOW:
case STATUS_FLOAT_STACK_CHECK:
case STATUS_FLOAT_UNDERFLOW:
case STATUS_FLOAT_MULTIPLE_FAULTS:
case STATUS_FLOAT_MULTIPLE_TRAPS:
X87CW(c) |= FPU_EXCEPTION_MASK; /* disable all FPU exceptions */
X87SW(c) &= ~FPU_STATUS_FLAGS; /* clear all pending FPU exceptions */
# ifdef _M_IX86
if (c->ContextFlags & CONTEXT_EXTENDED_REGISTERS) {
# endif
MXCSR(c) |= SSE_EXCEPTION_MASK; /* disable all SSE exceptions */
MXCSR(c) &= ~SSE_STATUS_FLAGS; /* clear all pending SSE exceptions */
# ifdef _M_IX86
}
# endif
return EXCEPTION_CONTINUE_EXECUTION;
}
LONG action = EXCEPTION_CONTINUE_SEARCH;
if (gFPEPreviousFilter) action = gFPEPreviousFilter(pe);
return action;
}
void InstallSignalHandlers(const char* aProgname) {
gFPEPreviousFilter = SetUnhandledExceptionFilter(FpeHandler);
}
# else
void InstallSignalHandlers(const char* aProgname) {}
# endif
#else
# error No signal handling implementation for this platform.
#endif
