//------------------------------------------------------------------------------
// frame::sender_for_compiled_frame
frame frame::sender_for_compiled_frame(RegisterMap* map) const {
assert(map != NULL, "map must be set");
// frame owned by optimizing compiler
assert(_cb->frame_size() >= 0, "must have non-zero frame size");
intptr_t* sender_sp = unextended_sp() + _cb->frame_size();
intptr_t* unextended_sp = sender_sp;
// On Intel the return_address is always the word on the stack
address sender_pc = (address) *(sender_sp-1);
// This is the saved value of EBP which may or may not really be an FP.
// It is only an FP if the sender is an interpreter frame (or C1?).
intptr_t** saved_fp_addr = (intptr_t**) (sender_sp - frame::sender_sp_offset);
if (map->update_map()) {
// Tell GC to use argument oopmaps for some runtime stubs that need it.
// For C1, the runtime stub might not have oop maps, so set this flag
// outside of update_register_map.
map->set_include_argument_oops(_cb->caller_must_gc_arguments(map->thread()));
if (_cb->oop_maps() != NULL) {
OopMapSet::update_register_map(this, map);
}
// Since the prolog does the save and restore of EBP there is no oopmap
// for it so we must fill in its location as if there was an oopmap entry
// since if our caller was compiled code there could be live jvm state in it.
update_map_with_saved_link(map, saved_fp_addr);
}
assert(sender_sp != sp(), "must have changed");
return frame(sender_sp, unextended_sp, *saved_fp_addr, sender_pc);
}
inline bool frame::equal(frame other) const {
bool ret = sp() == other.sp()
&& unextended_sp() == other.unextended_sp()
&& fp() == other.fp()
&& pc() == other.pc();
assert(!ret || ret && cb() == other.cb() && _deopt_state == other._deopt_state, "inconsistent construction");
return ret;
}
bool frame::is_interpreted_frame_valid(JavaThread* thread) const {
assert(is_interpreted_frame(), "Not an interpreted frame");
// These are reasonable sanity checks
if (fp() == 0 || (intptr_t(fp()) & (2*wordSize-1)) != 0) {
return false;
}
if (sp() == 0 || (intptr_t(sp()) & (2*wordSize-1)) != 0) {
return false;
}
const intptr_t interpreter_frame_initial_sp_offset = interpreter_frame_vm_local_words;
if (fp() + interpreter_frame_initial_sp_offset < sp()) {
return false;
}
// These are hacks to keep us out of trouble.
// The problem with these is that they mask other problems
if (fp() <= sp()) { // this attempts to deal with unsigned comparison above
return false;
}
// do some validation of frame elements
// first the method
Method* m = *interpreter_frame_method_addr();
// validate the method we'd find in this potential sender
if (!m->is_valid_method()) return false;
// stack frames shouldn't be much larger than max_stack elements
if (fp() - unextended_sp() > 1024 + m->max_stack()*Interpreter::stackElementSize) {
return false;
}
// validate bci/bcp
address bcp = interpreter_frame_bcp();
if (m->validate_bci_from_bcp(bcp) < 0) {
return false;
}
// validate ConstantPoolCache*
ConstantPoolCache* cp = *interpreter_frame_cache_addr();
if (cp == NULL || !cp->is_metaspace_object()) return false;
// validate locals
address locals = (address) *interpreter_frame_locals_addr();
if (locals > thread->stack_base() || locals < (address) fp()) return false;
// We'd have to be pretty unlucky to be mislead at this point
return true;
}
intptr_t* frame::real_fp() const {
if (_cb != NULL) {
// use the frame size if valid
int size = _cb->frame_size();
if (size > 0) {
return unextended_sp() + size;
}
}
// else rely on fp()
assert(! is_compiled_frame(), "unknown compiled frame size");
return fp();
}
intptr_t* frame::entry_frame_argument_at(int offset) const {
// convert offset to index to deal with tsi
int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
// Entry frame's arguments are always in relation to unextended_sp()
return &unextended_sp()[index];
}
bool frame::safe_for_sender(JavaThread *thread) {
address _SP = (address) sp();
address _FP = (address) fp();
address _UNEXTENDED_SP = (address) unextended_sp();
// sp must be within the stack
bool sp_safe = (_SP <= thread->stack_base()) &&
(_SP >= thread->stack_base() - thread->stack_size());
if (!sp_safe) {
return false;
}
// unextended sp must be within the stack and above or equal sp
bool unextended_sp_safe = (_UNEXTENDED_SP <= thread->stack_base()) &&
(_UNEXTENDED_SP >= _SP);
if (!unextended_sp_safe) return false;
// an fp must be within the stack and above (but not equal) sp
bool fp_safe = (_FP <= thread->stack_base()) &&
(_FP > _SP);
// We know sp/unextended_sp are safe only fp is questionable here
// If the current frame is known to the code cache then we can attempt to
// to construct the sender and do some validation of it. This goes a long way
// toward eliminating issues when we get in frame construction code
if (_cb != NULL ) {
// First check if frame is complete and tester is reliable
// Unfortunately we can only check frame complete for runtime stubs and nmethod
// other generic buffer blobs are more problematic so we just assume they are
// ok. adapter blobs never have a frame complete and are never ok.
if (!_cb->is_frame_complete_at(_pc)) {
if (_cb->is_nmethod() || _cb->is_adapter_blob() || _cb->is_runtime_stub()) {
return false;
}
}
// Entry frame checks
if (is_entry_frame()) {
// an entry frame must have a valid fp.
if (!fp_safe) {
return false;
}
// Validate the JavaCallWrapper an entry frame must have
address jcw = (address)entry_frame_call_wrapper();
bool jcw_safe = (jcw <= thread->stack_base()) && ( jcw > _FP);
return jcw_safe;
}
intptr_t* younger_sp = sp();
intptr_t* _SENDER_SP = sender_sp(); // sender is actually just _FP
bool adjusted_stack = is_interpreted_frame();
address sender_pc = (address)younger_sp[I7->sp_offset_in_saved_window()] + pc_return_offset;
// We must always be able to find a recognizable pc
CodeBlob* sender_blob = CodeCache::find_blob_unsafe(sender_pc);
if (sender_pc == NULL || sender_blob == NULL) {
return false;
}
// It should be safe to construct the sender though it might not be valid
frame sender(_SENDER_SP, younger_sp, adjusted_stack);
// Do we have a valid fp?
address sender_fp = (address) sender.fp();
// an fp must be within the stack and above (but not equal) current frame's _FP
bool sender_fp_safe = (sender_fp <= thread->stack_base()) &&
(sender_fp > _FP);
if (!sender_fp_safe) {
return false;
}
// If the potential sender is the interpreter then we can do some more checking
if (Interpreter::contains(sender_pc)) {
return sender.is_interpreted_frame_valid(thread);
}
// Could just be some random pointer within the codeBlob
if (!sender.cb()->code_contains(sender_pc)) {
return false;
}
// We should never be able to see an adapter if the current frame is something from code cache
if (sender_blob->is_adapter_blob()) {
return false;
}
if( sender.is_entry_frame()) {
// Validate the JavaCallWrapper an entry frame must have
address jcw = (address)sender.entry_frame_call_wrapper();
bool jcw_safe = (jcw <= thread->stack_base()) && ( jcw > sender_fp);
return jcw_safe;
}
// If the frame size is 0 something is bad because every nmethod has a non-zero frame size
// because you must allocate window space
if (sender_blob->frame_size() == 0) {
assert(!sender_blob->is_nmethod(), "should count return address at least");
return false;
}
// The sender should positively be an nmethod or call_stub. On sparc we might in fact see something else.
// The cause of this is because at a save instruction the O7 we get is a leftover from an earlier
// window use. So if a runtime stub creates two frames (common in fastdebug/jvmg) then we see the
// stale pc. So if the sender blob is not something we'd expect we have little choice but to declare
// the stack unwalkable. pd_get_top_frame_for_signal_handler tries to recover from this by unwinding
// that initial frame and retrying.
if (!sender_blob->is_nmethod()) {
return false;
}
// Could put some more validation for the potential non-interpreted sender
// frame we'd create by calling sender if I could think of any. Wait for next crash in forte...
// One idea is seeing if the sender_pc we have is one that we'd expect to call to current cb
// We've validated the potential sender that would be created
return true;
}
// Must be native-compiled frame. Since sender will try and use fp to find
// linkages it must be safe
if (!fp_safe) return false;
// could try and do some more potential verification of native frame if we could think of some...
return true;
}
// Return unique id for this frame. The id must have a value where we can distinguish
// identity and younger/older relationship. NULL represents an invalid (incomparable)
// frame.
inline intptr_t* frame::id(void) const { return unextended_sp(); }
