static void ptrace_wait_for_inferior_to_reach_syscall(pid_t inferior, int sysno)
{
struct user_regs_struct regs;
int syscall_number;
int status;
int count = 0;
while (1) {
count ++;
JASSERT(_real_ptrace(PTRACE_SYSCALL, inferior, 0, 0) == 0)
(inferior) (JASSERT_ERRNO);
JASSERT(_real_wait4(inferior, &status, __WALL, NULL) == inferior)
(inferior) (JASSERT_ERRNO);
JASSERT(_real_ptrace(PTRACE_GETREGS, inferior, 0, ®s) == 0)
(inferior) (JASSERT_ERRNO);
syscall_number = regs.ORIG_AX_REG;
if (syscall_number == sysno) {
JASSERT(_real_ptrace(PTRACE_SYSCALL, inferior, 0, (void*) 0) == 0)
(inferior) (JASSERT_ERRNO);
JASSERT(_real_wait4(inferior, &status, __WALL, NULL) == inferior)
(inferior) (JASSERT_ERRNO);
break;
}
}
return;
}
extern "C" pid_t wait4(pid_t pid, void *stat, int options,
struct rusage *rusage)
{
int status;
struct rusage rusagebuf;
pid_t retval;
int *stat_loc = (int*) stat;
if (stat_loc == NULL) {
stat_loc = &status;
}
if (rusage == NULL) {
rusage = &rusagebuf;
}
retval = dmtcp::PtraceInfo::instance().getWait4Status(pid, stat_loc, rusage);
if (retval != -1) {
return retval;
}
retval = _real_wait4(pid, stat_loc, options, rusage);
if (retval > 0 && dmtcp::PtraceInfo::instance().isPtracing()) {
if (WIFSTOPPED(*stat_loc)) {
dmtcp::PtraceInfo::instance().setLastCmd(retval, -1);
} else if (WIFEXITED(*stat_loc) || WIFSIGNALED(*stat_loc)) {
dmtcp::PtraceInfo::instance().eraseInferior(retval);
}
}
return retval;
}
pid_t wait4(pid_t pid, __WAIT_STATUS status, int options, struct rusage *rusage)
{
int stat;
int saved_errno = errno;
pid_t retval = 0;
if (status == NULL) {
status = (__WAIT_STATUS) &stat;
}
retval = _real_wait4(pid, status, options, rusage);
saved_errno = errno;
if (retval > 0 &&
(WIFEXITED(*(int*)status) || WIFSIGNALED(*(int*)status))) {
dmtcp::ProcessInfo::instance().eraseChild(retval);
}
errno = saved_errno;
return retval;
}
pid_t wait4(pid_t pid, __WAIT_STATUS status, int options, struct rusage *rusage)
{
int stat;
int saved_errno = errno;
pid_t currPid;
pid_t virtualPid;
pid_t retval = 0;
struct timespec sleepTime = {0, 10*000};
if (status == NULL)
status = (__WAIT_STATUS) &stat;
while (retval == 0) {
DMTCP_PLUGIN_DISABLE_CKPT();
currPid = VIRTUAL_TO_REAL_PID(pid);
retval = _real_wait4(currPid, status, options | WNOHANG, rusage);
saved_errno = errno;
virtualPid = REAL_TO_VIRTUAL_PID(retval);
if (retval > 0 &&
(WIFEXITED(*(int*)status) || WIFSIGNALED(*(int*)status))) {
dmtcp::VirtualPidTable::instance().erase(virtualPid);
}
DMTCP_PLUGIN_ENABLE_CKPT();
if ((options & WNOHANG) || retval != 0) {
break;
} else {
if (sleepTime.tv_sec == 0) {
sleepTime.tv_nsec *= 2;
if (sleepTime.tv_nsec >= 1000 * 1000 * 1000) {
sleepTime.tv_sec++;
sleepTime.tv_nsec = 0;
}
}
nanosleep(&sleepTime, NULL);
}
}
errno = saved_errno;
return virtualPid;
}
static void ptrace_single_step_thread(dmtcp::Inferior *inferiorInfo,
int isRestart)
{
struct user_regs_struct regs;
long peekdata;
long low, upp;
int status;
unsigned long addr;
unsigned long int eflags;
pid_t inferior = inferiorInfo->tid();
pid_t superior = GETTID();
int last_command = inferiorInfo->lastCmd();
char inferior_st = inferiorInfo->state();
while(1) {
int status;
JASSERT(_real_ptrace(PTRACE_SINGLESTEP, inferior, 0, 0) != -1)
(superior) (inferior) (JASSERT_ERRNO);
if (_real_wait4(inferior, &status, 0, NULL) == -1) {
JASSERT(_real_wait4(inferior, &status, __WCLONE, NULL) != -1)
(superior) (inferior) (JASSERT_ERRNO);
}
if (WIFEXITED(status)) {
JTRACE("thread is dead") (inferior) (WEXITSTATUS(status));
} else if(WIFSIGNALED(status)) {
JTRACE("thread terminated by signal") (inferior);
}
JASSERT(_real_ptrace(PTRACE_GETREGS, inferior, 0, ®s) != -1)
(superior) (inferior) (JASSERT_ERRNO);
peekdata = _real_ptrace(PTRACE_PEEKDATA, inferior, (void*) regs.IP_REG, 0);
long inst = peekdata & 0xffff;
#ifdef __x86_64__
/* For 64 bit architectures. */
if (inst == SIGRETURN_INST_16 && regs.AX_REG == 0xf) {
#else /* For 32 bit architectures.*/
if (inst == SIGRETURN_INST_16 && (regs.AX_REG == DMTCP_SYS_sigreturn ||
regs.AX_REG == DMTCP_SYS_rt_sigreturn)) {
#endif
if (isRestart) { /* Restart time. */
// FIXME: TODO:
if (last_command == PTRACE_SINGLESTEP) {
if (regs.AX_REG != DMTCP_SYS_rt_sigreturn) {
addr = regs.SP_REG;
} else {
addr = regs.SP_REG + 8;
addr = _real_ptrace(PTRACE_PEEKDATA, inferior, (void*) addr, 0);
addr += 20;
}
addr += EFLAGS_OFFSET;
errno = 0;
JASSERT ((eflags = _real_ptrace(PTRACE_PEEKDATA, inferior,
(void *)addr, 0)) != -1)
(superior) (inferior) (JASSERT_ERRNO);
eflags |= 0x0100;
JASSERT(_real_ptrace(PTRACE_POKEDATA, inferior, (void *)addr,
(void*) eflags) != -1)
(superior) (inferior) (JASSERT_ERRNO);
} else if (inferior_st != PTRACE_PROC_TRACING_STOP) {
/* TODO: remove in future as GROUP restore becames stable
* - Artem */
JASSERT(_real_ptrace(PTRACE_CONT, inferior, 0, 0) != -1)
(superior) (inferior) (JASSERT_ERRNO);
}
} else { /* Resume time. */
if (inferior_st != PTRACE_PROC_TRACING_STOP) {
JASSERT(_real_ptrace(PTRACE_CONT, inferior, 0, 0) != -1)
(superior) (inferior) (JASSERT_ERRNO);
}
}
/* In case we have checkpointed at a breakpoint, we don't want to
* hit the same breakpoint twice. Thus this code. */
// TODO: FIXME: Replace this code with a raise(SIGTRAP) and see what happens
if (inferior_st == PTRACE_PROC_TRACING_STOP) {
JASSERT(_real_ptrace(PTRACE_SINGLESTEP, inferior, 0, 0) != -1)
(superior) (inferior) (JASSERT_ERRNO);
if (_real_wait4(inferior, &status, 0, NULL) == -1) {
JASSERT(_real_wait4(inferior, &status, __WCLONE, NULL) != -1)
(superior) (inferior) (JASSERT_ERRNO);
}
}
break;
}
} //while(1)
}
/* This function detaches the user threads. */
static void ptrace_detach_user_threads ()
{
PtraceProcState pstate;
int status;
struct rusage rusage;
dmtcp::vector<dmtcp::Inferior*> inferiors;
inferiors = dmtcp::PtraceInfo::instance().getInferiors(GETTID());
for (size_t i = 0; i < inferiors.size(); i++) {
pid_t inferior = inferiors[i]->tid();
void *data = (void*) (unsigned long) dmtcp_get_ckpt_signal();
pstate = procfs_state(inferiors[i]->tid());
if (pstate == PTRACE_PROC_INVALID) {
JTRACE("Inferior does not exist.") (inferior);
dmtcp::PtraceInfo::instance().eraseInferior(inferior);
continue;
}
inferiors[i]->setState(pstate);
inferiors[i]->semInit();
if (inferiors[i]->isCkptThread()) {
data = NULL;
}
int ret = _real_wait4(inferior, &status, __WALL | WNOHANG, &rusage);
if (ret > 0) {
if (!WIFSTOPPED(status) || WSTOPSIG(status) != dmtcp_get_ckpt_signal()) {
inferiors[i]->setWait4Status(&status, &rusage);
}
}
pstate = procfs_state(inferiors[i]->tid());
if (pstate == PTRACE_PROC_RUNNING || pstate == PTRACE_PROC_SLEEPING) {
syscall(SYS_tkill, inferior, SIGSTOP);
_real_wait4(inferior, &status, __WALL, NULL);
JASSERT(_real_wait4(inferior, &status, __WALL | WNOHANG, NULL) == 0)
(inferior) (JASSERT_ERRNO);
}
if (_real_ptrace(PTRACE_DETACH, inferior, 0, data) == -1) {
JASSERT(errno == ESRCH)
(GETTID()) (inferior) (JASSERT_ERRNO);
dmtcp::PtraceInfo::instance().eraseInferior(inferior);
continue;
}
pstate = procfs_state(inferiors[i]->tid());
if (pstate == PTRACE_PROC_STOPPED) {
kill(inferior, SIGCONT);
}
JTRACE("Detached thread") (inferior);
}
}
static void ptrace_attach_threads(int isRestart)
{
pid_t inferior;
int status;
dmtcp::vector<dmtcp::Inferior*> inferiors;
inferiors = dmtcp::PtraceInfo::instance().getInferiors(GETTID());
if (inferiors.size() == 0) {
return;
}
JTRACE("Attaching to inferior threads") (GETTID());
// Attach to all inferior user threads.
for (size_t i = 0; i < inferiors.size(); i++) {
inferior = inferiors[i]->tid();
JASSERT(inferiors[i]->state() != PTRACE_PROC_INVALID) (GETTID()) (inferior);
if (!inferiors[i]->isCkptThread()) {
JASSERT(_real_ptrace(PTRACE_ATTACH, inferior, 0, 0) != -1)
(GETTID()) (inferior) (JASSERT_ERRNO);
JASSERT(_real_wait4(inferior, &status, __WALL, NULL) != -1)
(inferior) (JASSERT_ERRNO);
JASSERT(_real_ptrace(PTRACE_SETOPTIONS, inferior, 0,
inferiors[i]->getPtraceOptions()) != -1)
(GETTID()) (inferior) (inferiors[i]->getPtraceOptions()) (JASSERT_ERRNO);
// Run all user threads until the end of syscall(DMTCP_FAKE_SYSCALL)
dmtcp::PtraceInfo::instance().processPreResumeAttach(inferior);
ptrace_wait_for_inferior_to_reach_syscall(inferior, DMTCP_FAKE_SYSCALL);
}
}
// Attach to and run all user ckpthreads until the end of syscall(DMTCP_FAKE_SYSCALL)
for (size_t i = 0; i < inferiors.size(); i++) {
inferior = inferiors[i]->tid();
if (inferiors[i]->isCkptThread()) {
JASSERT(_real_ptrace(PTRACE_ATTACH, inferior, 0, 0) != -1)
(GETTID()) (inferior) (JASSERT_ERRNO);
JASSERT(_real_wait4(inferior, &status, __WALL, NULL) != -1)
(inferior) (JASSERT_ERRNO);
JASSERT(_real_ptrace(PTRACE_SETOPTIONS, inferior, 0,
inferiors[i]->getPtraceOptions()) != -1)
(GETTID()) (inferior) (inferiors[i]->getPtraceOptions()) (JASSERT_ERRNO);
// Wait for all inferiors to execute dummy syscall 'DMTCP_FAKE_SYSCALL'.
dmtcp::PtraceInfo::instance().processPreResumeAttach(inferior);
ptrace_wait_for_inferior_to_reach_syscall(inferior, DMTCP_FAKE_SYSCALL);
}
}
// Singlestep all user threads out of the signal handler
for (size_t i = 0; i < inferiors.size(); i++) {
int lastCmd = inferiors[i]->lastCmd();
inferior = inferiors[i]->tid();
if (!inferiors[i]->isCkptThread()) {
/* After attach, the superior needs to singlestep the inferior out of
* stopthisthread, aka the signal handler. */
ptrace_single_step_thread(inferiors[i], isRestart);
if (inferiors[i]->isStopped() && (lastCmd == PTRACE_CONT ||
lastCmd == PTRACE_SYSCALL)) {
JASSERT(_real_ptrace(lastCmd, inferior, 0, 0) != -1)
(GETTID()) (inferior) (JASSERT_ERRNO);
}
}
}
// Move ckpthreads to next step (depending on state)
for (size_t i = 0; i < inferiors.size(); i++) {
int lastCmd = inferiors[i]->lastCmd();
inferior = inferiors[i]->tid();
if (inferiors[i]->isCkptThread() && !inferiors[i]->isStopped() &&
(lastCmd == PTRACE_CONT || lastCmd == PTRACE_SYSCALL)) {
JASSERT(_real_ptrace(lastCmd, inferior, 0, 0) != -1)
(GETTID()) (inferior) (JASSERT_ERRNO);
}
}
JTRACE("thread done") (GETTID());
}
