forte.cpp revision 1472
3909N/A * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved. 1008N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 1008N/A * This code is free software; you can redistribute it and/or modify it 1008N/A * under the terms of the GNU General Public License version 2 only, as 2362N/A * published by the Free Software Foundation. 2362N/A * This code is distributed in the hope that it will be useful, but WITHOUT 1008N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1008N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1008N/A * version 2 for more details (a copy is included in the LICENSE file that 1008N/A * You should have received a copy of the GNU General Public License version 1008N/A * 2 along with this work; if not, write to the Free Software Foundation, 1008N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 1008N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 1008N/A#
include "incls/_precompiled.incl" 0N/A// These name match the names reported by the forte quality kit 2391N/A//------------------------------------------------------- 1821N/A// Native interfaces for use by Forte tools. 1821N/A // constructor that starts with sender of frame fr (top_frame) 1821N/A // We must always have a valid frame to start filling 4634N/A// Solaris SPARC Compiler1 needs an additional check on the grandparent 4634N/A// of the top_frame when the parent of the top_frame is interpreted and 4634N/A// the grandparent is compiled. However, in this method we do not know 4634N/A// the relationship of the current _frame relative to the top_frame so 4634N/A// we implement a more broad sanity check. When the previous callee is 4634N/A// interpreted and the current sender is compiled, we verify that the 4634N/A// current sender is also walkable. If it is not walkable, then we mark 4634N/A// the current vframeStream as at the end. 2402N/A // handle frames with inlining 2402N/A // By the time we get here we should never see unsafe but better 2228N/A// Determine if 'fr' is a decipherable compiled frame. We are already 2228N/A// assured that fr is for a java nmethod. 2402N/A // We're stopped at a call into the JVM so look for a PcDesc with 2402N/A // the actual pc reported by the frame. 2402N/A // Did we find a useful PcDesc? 2402N/A // We're at some random pc in the nmethod so search for the PcDesc 2402N/A // whose pc is greater than the current PC. It's done this way 2402N/A // because the extra PcDescs that are recorded for improved debug 2402N/A // info record the end of the region covered by the ScopeDesc 2402N/A // instead of the beginning. 2402N/A // Now do we have a useful PcDesc? 2228N/A // No debug information available for this pc 2228N/A // vframeStream would explode if we try and walk the frames. 2228N/A // This PcDesc is useful however we must adjust the frame's pc 2228N/A // so that the vframeStream lookups will use this same pc 1821N/A// Determine if 'fr' is a walkable interpreted frame. Returns false 1821N/A// if it is not. *method_p, and *bci_p are not set when false is 2228N/A// returned. *method_p is non-NULL if frame was executing a Java 2228N/A// method. *bci_p is != -1 if a valid BCI in the Java method could 2228N/A// Note: this method returns true when a valid Java method is found 2228N/A// even if a valid BCI cannot be found. 1821N/A // top frame is an interpreted frame 1821N/A // check if it is walkable (i.e. valid methodOop and valid bci) 1821N/A // Because we may be racing a gc thread the method and/or bci 1821N/A // of a valid interpreter frame may look bad causing us to 1821N/A // fail the is_interpreted_frame_valid test. If the thread 1821N/A // is in any of the following states we are assured that the 1821N/A // frame is in fact valid and we must have hit the race. 1821N/A // The frame code should completely validate the frame so that 1821N/A // references to methodOop and bci are completely safe to access 1821N/A // If they aren't the frame code should be fixed not this 0N/A // code. However since gc isn't locked out the values could be 1821N/A // stale. This is a race we can never completely win since we can't 1008N/A // lock out gc so do one last check after retrieving their values 0N/A // from the frame for additional safety 2228N/A // We've at least found a method. 2228N/A // NOTE: there is something to be said for the approach that 2228N/A // if we don't find a valid bci then the method is not likely 2228N/A // a valid method. Then again we may have caught an interpreter 0N/A // frame in the middle of construction and the bci field is 1008N/A // See if gc may have invalidated method since we validated frame 1008N/A // note: bci is set to -1 if not a valid bci 1008N/A// Determine if 'fr' can be used to find an initial Java frame. 1008N/A// Return false if it can not find a fully decipherable Java frame 1008N/A// (in other words a frame that isn't safe to use in a vframe stream). 1008N/A// Obviously if it can't even find a Java frame false will also be returned. 1008N/A// If we find a Java frame decipherable or not then by definition we have 1821N/A// identified a method and that will be returned to the caller via method_p. 1008N/A// If we can determine a bci that is returned also. (Hmm is it possible 1008N/A// to return a method and bci and still return false? ) 0N/A// The initial Java frame we find (if any) is return via initial_frame_p. 1821N/A // It is possible that for a frame containing an nmethod 1821N/A // we can capture the method but no bci. If we get no 1821N/A // bci the frame isn't walkable but the method is usable. 1821N/A // Therefore we init the returned methodOop to NULL so the 1821N/A // caller can make the distinction. 1821N/A // On the initial call to this method the frame we get may not be 1821N/A // recognizable to us. This should only happen if we are in a JRT_LEAF 1821N/A // or something called by a JRT_LEAF method. 2391N/A // If the starting frame we were given has no codeBlob associated with 2391N/A // it see if we can find such a frame because only frames with codeBlobs 1008N/A // are possible Java frames. 1008N/A // See if we can find a useful frame 1821N/A // We have a frame known to be in the codeCache 1947N/A // We will hopefully be able to figure out something to do with it. 1947N/A // If initial frame is frame from StubGenerator and there is no 2017N/A // previous anchor, there are no java frames associated with a method 1821N/A // Hopefully we got some data 1821N/A // If the frame isn't fully decipherable then the default 1821N/A // value for the bci is a signal that we don't have a bci. 1821N/A // If we have a decipherable frame this bci value will 1821N/A // Native wrapper code is trivial to decode by vframeStream 1821N/A // If it isn't decipherable then we have found a pc that doesn't 1821N/A // have a PCDesc that can get us a bci however we did find 1821N/A // is_decipherable_compiled_frame may modify candidate's pc 1008N/A // Must be some stub frame that we don't care about 0N/A // If it isn't in the code cache something is wrong 0N/A // since once we find a frame in the code cache they 1934N/A// call frame copied from old .h file and renamed 1821N/A// call trace copied from old .h file and renamed 3866N/A // The frame might not be walkable but still recovered a method 1821N/A // (e.g. an nmethod with no scope info for the pc 2228N/A // The method is not stored GC safe so see if GC became active 1934N/A // after we entered AsyncGetCallTrace() and before we try to 2228N/A // Yes, there is still a window after this check and before 1934N/A // we use methodOop below, but we can't lock out GC so that 1934N/A // has to be an acceptable risk. 1821N/A // We got a Java frame however it isn't fully decipherable 1821N/A // so it won't necessarily be safe to use it for the 1821N/A // initial frame in the vframe stream. 1934N/A // Take whatever method the top-frame decoder managed to scrape up. 1934N/A // We look further at the top frame only if non-safepoint 1934N/A // debugging information is available. 1821N/A // The method is not stored GC safe so see if GC became active 1821N/A // after we entered AsyncGetCallTrace() and before we try to 3740N/A // Yes, there is still a window after this check and before 1821N/A // we use methodOop below, but we can't lock out GC so that 1821N/A // has to be an acceptable risk. 1821N/A // we throw away everything we've gathered in this sample since 3740N/A// Forte Analyzer AsyncGetCallTrace() entry point. Currently supported 1821N/A// on Linux X86, Solaris SPARC and Solaris X86. 2017N/A// Async-safe version of GetCallTrace being called from a signal handler 1934N/A// when a LWP gets interrupted by SIGPROF but the stack traces are filled 1934N/A// with different content (see below). 1821N/A// CLASS_LOAD events have been enabled since agent startup. The enabled 3740N/A// event will cause the jmethodIDs to be allocated at class load time. 1821N/A// The jmethodIDs cannot be allocated in a signal handler because locks 1821N/A// cannot be grabbed in a signal handler safely. 1821N/A// void (*AsyncGetCallTrace)(ASGCT_CallTrace *trace, jint depth, void* ucontext) 1821N/A// Called by the profiler to obtain the current method call stack trace for 1821N/A// a given thread. The thread is identified by the env_id field in the 1821N/A// ASGCT_CallTrace structure. The profiler agent should allocate a ASGCT_CallTrace 1821N/A// structure with enough memory for the requested stack depth. The VM fills in 1821N/A// the frames buffer and the num_frames field. 1821N/A// trace - trace data structure to be filled by the VM. 1821N/A// depth - depth of the call stack trace. 1821N/A// ucontext - ucontext_t of the LWP 3740N/A// env_id - ID of thread which executed this trace. 1821N/A// num_frames - number of frames in the trace. 1821N/A// (< 0 indicates the frame is not walkable). 1821N/A// frames - the ASGCT_CallFrames that make up this trace. Callee followed by callers. 1821N/A// 1) For Java frame (interpreted and compiled), 3740N/A// lineno - bci of the method being executed or -1 if bci is not available 1821N/A// method_id - jmethodID of the method being executed 1821N/A// method_id - jmethodID of the method being executed 1821N/A// This is if'd out because we no longer use thread suspension. 3740N/A// However if someone wanted to backport this to a 5.0 jvm then this 2017N/A // The safepoint mechanism is trying to synchronize all the threads. 2546N/A // Since this can involve thread suspension, it is not safe for us 1821N/A // to be here. We can reduce the deadlock risk window by quickly 4499N/A // returning to the SIGPROF handler. However, it is still possible 2546N/A // for VMThread to catch us here or in the SIGPROF handler. If we 1821N/A // are suspended while holding a resource and another thread blocks 2017N/A // on that resource in the SIGPROF handler, then we will have a 1934N/A // three-thread deadlock (VMThread, this thread, the other thread). 1821N/A // bad env_id, thread has exited or thread is exiting 1821N/A // thread is in the deoptimization handler so return no frames 2017N/A "AsyncGetCallTrace must be called by the current interrupted thread");
1821N/A // We found the thread on the threads list above, but it is too 1821N/A // young to be useful so return that there are no Java frames. 2017N/A // param isInJava == false - indicate we aren't in Java code 1934N/A // This assert would seem to be valid but it is not. 1934N/A // It would be valid if we weren't possibly racing a gc 1821N/A // thread. A gc thread can make a valid interpreted frame 1821N/A // look invalid. It's a small window but it does happen. 3740N/A // The assert is left here commented out as a reminder. 1821N/A // assert(trace->num_frames != ticks_not_walkable_not_Java, "should always be walkable"); 1821N/A // param isInJava == true - indicate we are in Java code 2020N/A// Support for the Forte(TM) Peformance Tools collector. 2020N/A// information, please see the libcollect man page. 1821N/A// Method to let libcollector know about a dynamically loaded function. 2020N/A// Because it is weakly bound, the calls become NOP's when the library 1821N/A "Code size exceeds maximum range");
1008N/A#
endif // !_WINDOWS && !IA64