1 /*
2  * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
3  *
4  * This code is free software; you can redistribute it and/or modify it
5  * under the terms of the GNU General Public License version 2 only, as
6  * published by the Free Software Foundation.
7  *
8  * This code is distributed in the hope that it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
11  * version 2 for more details (a copy is included in the LICENSE file that
12  * accompanied this code).
13  *
14  * You should have received a copy of the GNU General Public License version
15  * 2 along with this work; if not, write to the Free Software Foundation,
16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17  *
18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19  * or visit www.oracle.com if you need additional information or have any
20  * questions.
21  *
22  */
23 
24 #ifndef SHARE_SERVICES_THREADSTACKTRACKER_HPP
25 #define SHARE_SERVICES_THREADSTACKTRACKER_HPP
26 
27 #if INCLUDE_NMT
28 
29 #include "services/allocationSite.hpp"
30 #include "services/mallocSiteTable.hpp"
31 #include "services/nmtCommon.hpp"
32 #include "utilities/nativeCallStack.hpp"
33 #include "utilities/linkedlist.hpp"
34 
35 class SimpleThreadStackSite;
36 
37 class SimpleThreadStack {
38   friend class SimpleThreadStackSite;
39 private:
40   address _base;
41   size_t  _size;
42 public:
SimpleThreadStack()43   SimpleThreadStack() : _base(NULL), _size(0) { }
equals(const SimpleThreadStack & s) const44   bool equals(const SimpleThreadStack& s) const {
45     return base() == s.base();
46   }
47 
size() const48   size_t  size() const { return _size; }
base() const49   address base() const { return _base; }
50 private:
set_size(size_t size)51   void set_size(size_t size)  { _size = size; }
set_base(address base)52   void set_base(address base) { _base = base; }
53 };
54 
55 class SimpleThreadStackSite : public AllocationSite<SimpleThreadStack> {
56 public:
SimpleThreadStackSite(address base,size_t size,const NativeCallStack & stack)57   SimpleThreadStackSite(address base, size_t size, const NativeCallStack& stack) :
58     AllocationSite<SimpleThreadStack>(stack, mtThreadStack) {
59     data()->set_size(size);
60     data()->set_base(base);
61   }
62 
SimpleThreadStackSite(address base,size_t size)63   SimpleThreadStackSite(address base, size_t size) :
64     AllocationSite<SimpleThreadStack>(NativeCallStack::empty_stack(), mtThreadStack) {
65     data()->set_base(base);
66     data()->set_size(size);
67   }
68 
equals(const SimpleThreadStackSite & mts) const69   bool equals(const SimpleThreadStackSite& mts) const {
70     bool eq = base() == mts.base();
71     assert(!eq || size() == mts.size(), "Must match");
72     return eq;
73   }
74 
size() const75   size_t  size() const { return peek()->size(); }
base() const76   address base() const { return peek()->base(); }
77 };
78 
79   /*
80    * Most of platforms, that hotspot support, have their thread stacks backed by
81    * virtual memory by default. For these cases, thread stack tracker simply
82    * delegates tracking to virtual memory tracker.
83    * However, there are exceptions, (e.g. AIX), that platforms can provide stacks
84    * that are not page aligned. A hypothetical VM implementation, it can provide
85    * it own stacks. In these case, track_as_vm() should return false and manage
86    * stack tracking by this tracker internally.
87    * During memory snapshot, tracked thread stacks memory data is walked and stored
88    * along with malloc'd data inside baseline. The regions are not scanned and assumed
89    * all committed for now. Can add scanning phase when there is a need.
90    */
91 class ThreadStackTracker : AllStatic {
92 private:
93   static volatile size_t _thread_count;
94 
95   static int compare_thread_stack_base(const SimpleThreadStackSite& s1, const SimpleThreadStackSite& s2);
96   static SortedLinkedList<SimpleThreadStackSite, compare_thread_stack_base>* _simple_thread_stacks;
97 public:
98   // Late phase initialization
99   static bool late_initialize(NMT_TrackingLevel level);
100   static bool transition(NMT_TrackingLevel from, NMT_TrackingLevel to);
101 
102   static void new_thread_stack(void* base, size_t size, const NativeCallStack& stack);
103   static void delete_thread_stack(void* base, size_t size);
104 
track_as_vm()105   static bool   track_as_vm()  { return AIX_ONLY(false) NOT_AIX(true); }
thread_count()106   static size_t thread_count() { return _thread_count; }
107 
108   // Snapshot support. Piggyback thread stack data in malloc slot, NMT always handles
109   // thread stack slot specially since beginning.
110   static bool walk_simple_thread_stack_site(MallocSiteWalker* walker);
111 };
112 
113 #endif // INCLUDE_NMT
114 #endif // SHARE_SERVICES_THREADSTACKTRACKER_HPP
115