/* * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, 2014 SAP SE. All rights reserved. * Copyright (c) 2022, IBM Corp. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. *
*/
frame JavaThread::pd_last_frame() {
assert(has_last_Java_frame(), "must have last_Java_sp() when suspended");
// Only called by current thread or when the thread is suspended. // No memory barrier needed, here. Only writer must write sp last (for use by profiler).
intptr_t* sp = last_Java_sp();
address pc = _anchor.last_Java_pc();
// If we have a last_Java_frame, then we should use it even if // isInJava == true. It should be more reliable than ucontext info. if (has_last_Java_frame() && frame_anchor()->walkable()) {
intptr_t* sp = last_Java_sp();
address pc = _anchor.last_Java_pc(); // pc can be seen as null because not all writers use store pc + release store sp. // Simply discard the sample in this very rare case. if (pc == nullptr) returnfalse;
*fr_addr = frame(sp, pc); returntrue;
}
// At this point, we don't have a last_Java_frame, so // we try to glean some information out of the ucontext // if we were running Java code when SIGPROF came in. if (isInJava) {
ucontext_t* uc = (ucontext_t*) ucontext;
address pc = (address)uc->uc_mcontext.jmp_context.iar;
if (ret_frame.fp() == NULL) { // The found frame does not have a valid frame pointer. // Bail out because this will create big trouble later on, either // - when using istate, calculated as (NULL - ijava_state_size) or // - when using fp() directly in safe_for_sender() // // There is no conclusive description (yet) how this could happen, but it does. // For more details on what was observed, see thread_linux_s390.cpp returnfalse;
}
if (ret_frame.is_interpreted_frame()) {
frame::ijava_state *istate = ret_frame.get_ijava_state(); const Method *m = (const Method*)(istate->method); if (!Method::is_valid_method(m)) returnfalse; if (!Metaspace::contains(m->constMethod())) returnfalse;
uint64_t reg_bcp = uc->uc_mcontext.jmp_context.gpr[14/*R14_bcp*/];
uint64_t istate_bcp = istate->bcp;
uint64_t code_start = (uint64_t)(m->code_base());
uint64_t code_end = (uint64_t)(m->code_base() + m->code_size()); if (istate_bcp >= code_start && istate_bcp < code_end) { // we have a valid bcp, don't touch it, do nothing
} elseif (reg_bcp >= code_start && reg_bcp < code_end) {
istate->bcp = reg_bcp;
} else { returnfalse;
}
} if (!ret_frame.safe_for_sender(this)) { // nothing else to try if the frame isn't good returnfalse;
}
*fr_addr = ret_frame; returntrue;
} // nothing else to try returnfalse;
}
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