// For Forte Analyzer AsyncGetCallTrace profiling support - thread is
// currently interrupted by SIGPROF
bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
void* ucontext,
bool isInJava) {
assert(Thread::current() == this, "caller must be current thread");
assert(this->is_Java_thread(), "must be JavaThread");
JavaThread* jt = (JavaThread *)this;
if (!isInJava) {
// make_walkable flushes register windows and grabs last_Java_pc
// which can not be done if the ucontext sp matches last_Java_sp
// stack walking utilities assume last_Java_pc set if marked flushed
jt->frame_anchor()->make_walkable(jt);
}
// If we have a walkable last_Java_frame, then we should use it
// even if isInJava == true. It should be more reliable than
// ucontext info.
if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
*fr_addr = jt->pd_last_frame();
return true;
}
ucontext_t* uc = (ucontext_t*) ucontext;
// At this point, we don't have a walkable last_Java_frame, so
// we try to glean some information out of the ucontext.
intptr_t* ret_sp;
ExtendedPC addr =
os::fetch_frame_from_context(uc, &ret_sp,
NULL /* ret_fp only used on X86 */);
if (addr.pc() == NULL || ret_sp == NULL) {
// ucontext wasn't useful
return false;
}
#if INCLUDE_CDS
if (UseSharedSpaces && MetaspaceShared::is_in_shared_region(addr.pc(), MetaspaceShared::md)) {
// In the middle of a trampoline call. Bail out for safety.
// This happens rarely so shouldn't affect profiling.
return false;
}
#endif
// we were running Java code when SIGPROF came in
if (isInJava) {
// If we have a last_Java_sp, then the SIGPROF signal caught us
// right when we were transitioning from _thread_in_Java to a new
// JavaThreadState. We use last_Java_sp instead of the sp from
// the ucontext since it should be more reliable.
if (jt->has_last_Java_frame()) {
ret_sp = jt->last_Java_sp();
}
// Implied else: we don't have a last_Java_sp so we use what we
// got from the ucontext.
frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
if (!ret_frame.safe_for_sender(jt)) {
// nothing else to try if the frame isn't good
return false;
}
*fr_addr = ret_frame;
return true;
}
// At this point, we know we weren't running Java code. We might
// have a last_Java_sp, but we don't have a walkable frame.
// However, we might still be able to construct something useful
// if the thread was running native code.
if (jt->has_last_Java_frame()) {
assert(!jt->frame_anchor()->walkable(), "case covered above");
if (jt->thread_state() == _thread_in_native) {
frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
if (!ret_frame.safe_for_sender(jt)) {
// nothing else to try if the frame isn't good
return false;
}
*fr_addr = ret_frame;
return true;
}
}
// nothing else to try
return false;
}
bool JavaThread::pd_get_top_frame(frame* fr_addr,
void* ucontext, bool isInJava, bool makeWalkable) {
assert(this->is_Java_thread(), "must be JavaThread");
JavaThread* jt = (JavaThread *)this;
if (!isInJava && makeWalkable) {
// make_walkable flushes register windows and grabs last_Java_pc
// which can not be done if the ucontext sp matches last_Java_sp
// stack walking utilities assume last_Java_pc set if marked flushed
jt->frame_anchor()->make_walkable(jt);
}
// If we have a walkable last_Java_frame, then we should use it
// even if isInJava == true. It should be more reliable than
// ucontext info.
if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
*fr_addr = jt->pd_last_frame();
return true;
}
ucontext_t* uc = (ucontext_t*) ucontext;
// At this point, we don't have a walkable last_Java_frame, so
// we try to glean some information out of the ucontext.
intptr_t* ret_sp;
ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
&ret_sp, NULL /* ret_fp only used on Solaris X86 */);
if (addr.pc() == NULL || ret_sp == NULL) {
// ucontext wasn't useful
return false;
}
#if INCLUDE_CDS
if (UseSharedSpaces && MetaspaceShared::is_in_shared_region(addr.pc(), MetaspaceShared::md)) {
// In the middle of a trampoline call. Bail out for safety.
// This happens rarely so shouldn't affect profiling.
return false;
}
#endif
frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
// we were running Java code when SIGPROF came in
if (isInJava) {
// If the frame we got is safe then it is most certainly valid
if (ret_frame.safe_for_sender(jt)) {
*fr_addr = ret_frame;
return true;
}
// If it isn't safe then we can try several things to try and get
// a good starting point.
//
// On sparc the frames are almost certainly walkable in the sense
// of sp/fp linkages. However because of recycling of windows if
// a piece of code does multiple save's where the initial save creates
// a real frame with a return pc and the succeeding save's are used to
// simply get free registers and have no real pc then the pc linkage on these
// "inner" temporary frames will be bogus.
// Since there is in general only a nesting level like
// this one deep in general we'll try and unwind such an "inner" frame
// here ourselves and see if it makes sense
frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
if (unwind_frame.safe_for_sender(jt)) {
*fr_addr = unwind_frame;
return true;
}
// Well that didn't work. Most likely we're toast on this tick
// The previous code would try this. I think it is dubious in light
// of changes to safe_for_sender and the unwind trick above but
// if it gets us a safe frame who wants to argue.
// If we have a last_Java_sp, then the SIGPROF signal caught us
// right when we were transitioning from _thread_in_Java to a new
// JavaThreadState. We use last_Java_sp instead of the sp from
// the ucontext since it should be more reliable.
if (jt->has_last_Java_frame()) {
ret_sp = jt->last_Java_sp();
frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
if (ret_frame2.safe_for_sender(jt)) {
*fr_addr = ret_frame2;
return true;
}
}
// This is the best we can do. We will only be able to decode the top frame
*fr_addr = ret_frame;
return true;
}
// At this point, we know we weren't running Java code. We might
// have a last_Java_sp, but we don't have a walkable frame.
// However, we might still be able to construct something useful
// if the thread was running native code.
if (jt->has_last_Java_frame()) {
assert(!jt->frame_anchor()->walkable(), "case covered above");
frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
*fr_addr = ret_frame;
return true;
}
// nothing else to try but what we found initially
*fr_addr = ret_frame;
return true;
}
