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8248186: Move CDS C++ vtable code to cppVtables.cpp
Reviewed-by: coleenp
1 parent 03a4df0 commit c5e63b6

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7 files changed

+391
-312
lines changed

7 files changed

+391
-312
lines changed

make/hotspot/lib/JvmFeatures.gmk

+1
Original file line numberDiff line numberDiff line change
@@ -121,6 +121,7 @@ ifneq ($(call check-jvm-feature, cds), true)
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classListParser.cpp \
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classLoaderDataShared.cpp \
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classLoaderExt.cpp \
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cppVtables.cpp \
124125
dumpAllocStats.cpp \
125126
dynamicArchive.cpp \
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filemap.cpp \

src/hotspot/share/memory/archiveBuilder.cpp

+2-1
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,7 @@
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#include "logging/logMessage.hpp"
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#include "memory/archiveBuilder.hpp"
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#include "memory/archiveUtils.hpp"
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#include "memory/cppVtables.hpp"
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#include "memory/dumpAllocStats.hpp"
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#include "memory/metaspaceShared.hpp"
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#include "memory/resourceArea.hpp"
@@ -479,7 +480,7 @@ void ArchiveBuilder::make_shallow_copy(DumpRegion *dump_region, SourceObjInfo* s
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480481
memcpy(dest, src, bytes);
481482

482-
intptr_t* archived_vtable = MetaspaceShared::get_archived_cpp_vtable(ref->msotype(), (address)dest);
483+
intptr_t* archived_vtable = CppVtables::get_archived_cpp_vtable(ref->msotype(), (address)dest);
483484
if (archived_vtable != NULL) {
484485
*(address*)dest = (address)archived_vtable;
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ArchivePtrMarker::mark_pointer((address*)dest);
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@@ -0,0 +1,332 @@
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/*
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* Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "logging/log.hpp"
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#include "memory/archiveUtils.hpp"
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#include "memory/cppVtables.hpp"
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#include "memory/metaspaceShared.hpp"
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#include "oops/instanceClassLoaderKlass.hpp"
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#include "oops/instanceMirrorKlass.hpp"
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#include "oops/instanceRefKlass.hpp"
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#include "oops/methodData.hpp"
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#include "oops/objArrayKlass.hpp"
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#include "oops/typeArrayKlass.hpp"
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#include "runtime/arguments.hpp"
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#include "utilities/globalDefinitions.hpp"
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// Objects of the Metadata types (such as Klass and ConstantPool) have C++ vtables.
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// (In GCC this is the field <Type>::_vptr, i.e., first word in the object.)
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//
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// Addresses of the vtables and the methods may be different across JVM runs,
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// if libjvm.so is dynamically loaded at a different base address.
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//
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// To ensure that the Metadata objects in the CDS archive always have the correct vtable:
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//
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// + at dump time: we redirect the _vptr to point to our own vtables inside
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// the CDS image
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// + at run time: we clone the actual contents of the vtables from libjvm.so
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// into our own tables.
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// Currently, the archive contain ONLY the following types of objects that have C++ vtables.
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#define CPP_VTABLE_PATCH_TYPES_DO(f) \
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f(ConstantPool) \
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f(InstanceKlass) \
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f(InstanceClassLoaderKlass) \
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f(InstanceMirrorKlass) \
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f(InstanceRefKlass) \
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f(Method) \
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f(ObjArrayKlass) \
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f(TypeArrayKlass)
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class CppVtableInfo {
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intptr_t _vtable_size;
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intptr_t _cloned_vtable[1];
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public:
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static int num_slots(int vtable_size) {
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return 1 + vtable_size; // Need to add the space occupied by _vtable_size;
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}
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int vtable_size() { return int(uintx(_vtable_size)); }
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void set_vtable_size(int n) { _vtable_size = intptr_t(n); }
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intptr_t* cloned_vtable() { return &_cloned_vtable[0]; }
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void zero() { memset(_cloned_vtable, 0, sizeof(intptr_t) * vtable_size()); }
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// Returns the address of the next CppVtableInfo that can be placed immediately after this CppVtableInfo
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static size_t byte_size(int vtable_size) {
76+
CppVtableInfo i;
77+
return pointer_delta(&i._cloned_vtable[vtable_size], &i, sizeof(u1));
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}
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};
80+
81+
static inline intptr_t* vtable_of(Metadata* m) {
82+
return *((intptr_t**)m);
83+
}
84+
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static inline DumpRegion* mc_region() {
86+
return MetaspaceShared::misc_code_dump_space();
87+
}
88+
89+
template <class T> class CppVtableCloner : public T {
90+
static CppVtableInfo* _info;
91+
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static int get_vtable_length(const char* name);
93+
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public:
95+
// Allocate and initialize the C++ vtable, starting from top, but do not go past end.
96+
static intptr_t* allocate(const char* name);
97+
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// Clone the vtable to ...
99+
static intptr_t* clone_vtable(const char* name, CppVtableInfo* info);
100+
101+
static void zero_vtable_clone() {
102+
assert(DumpSharedSpaces, "dump-time only");
103+
_info->zero();
104+
}
105+
106+
static bool is_valid_shared_object(const T* obj) {
107+
intptr_t* vptr = *(intptr_t**)obj;
108+
return vptr == _info->cloned_vtable();
109+
}
110+
111+
static void init_orig_cpp_vtptr(int kind);
112+
};
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template <class T> CppVtableInfo* CppVtableCloner<T>::_info = NULL;
115+
116+
template <class T>
117+
intptr_t* CppVtableCloner<T>::allocate(const char* name) {
118+
assert(is_aligned(mc_region()->top(), sizeof(intptr_t)), "bad alignment");
119+
int n = get_vtable_length(name);
120+
_info = (CppVtableInfo*)mc_region()->allocate(CppVtableInfo::byte_size(n), sizeof(intptr_t));
121+
_info->set_vtable_size(n);
122+
123+
intptr_t* p = clone_vtable(name, _info);
124+
assert((char*)p == mc_region()->top(), "must be");
125+
126+
return _info->cloned_vtable();
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}
128+
129+
template <class T>
130+
intptr_t* CppVtableCloner<T>::clone_vtable(const char* name, CppVtableInfo* info) {
131+
if (!DumpSharedSpaces) {
132+
assert(_info == 0, "_info is initialized only at dump time");
133+
_info = info; // Remember it -- it will be used by MetaspaceShared::is_valid_shared_method()
134+
}
135+
T tmp; // Allocate temporary dummy metadata object to get to the original vtable.
136+
int n = info->vtable_size();
137+
intptr_t* srcvtable = vtable_of(&tmp);
138+
intptr_t* dstvtable = info->cloned_vtable();
139+
140+
// We already checked (and, if necessary, adjusted n) when the vtables were allocated, so we are
141+
// safe to do memcpy.
142+
log_debug(cds, vtables)("Copying %3d vtable entries for %s", n, name);
143+
memcpy(dstvtable, srcvtable, sizeof(intptr_t) * n);
144+
return dstvtable + n;
145+
}
146+
147+
// To determine the size of the vtable for each type, we use the following
148+
// trick by declaring 2 subclasses:
149+
//
150+
// class CppVtableTesterA: public InstanceKlass {virtual int last_virtual_method() {return 1;} };
151+
// class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return NULL}; };
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//
153+
// CppVtableTesterA and CppVtableTesterB's vtables have the following properties:
154+
// - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N)
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// - The first N entries have are exactly the same as in InstanceKlass's vtable.
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// - Their last entry is different.
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//
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// So to determine the value of N, we just walk CppVtableTesterA and CppVtableTesterB's tables
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// and find the first entry that's different.
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//
161+
// This works on all C++ compilers supported by Oracle, but you may need to tweak it for more
162+
// esoteric compilers.
163+
164+
template <class T> class CppVtableTesterB: public T {
165+
public:
166+
virtual int last_virtual_method() {return 1;}
167+
};
168+
169+
template <class T> class CppVtableTesterA : public T {
170+
public:
171+
virtual void* last_virtual_method() {
172+
// Make this different than CppVtableTesterB::last_virtual_method so the C++
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// compiler/linker won't alias the two functions.
174+
return NULL;
175+
}
176+
};
177+
178+
template <class T>
179+
int CppVtableCloner<T>::get_vtable_length(const char* name) {
180+
CppVtableTesterA<T> a;
181+
CppVtableTesterB<T> b;
182+
183+
intptr_t* avtable = vtable_of(&a);
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intptr_t* bvtable = vtable_of(&b);
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// Start at slot 1, because slot 0 may be RTTI (on Solaris/Sparc)
187+
int vtable_len = 1;
188+
for (; ; vtable_len++) {
189+
if (avtable[vtable_len] != bvtable[vtable_len]) {
190+
break;
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}
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}
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log_debug(cds, vtables)("Found %3d vtable entries for %s", vtable_len, name);
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return vtable_len;
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}
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#define ALLOC_CPP_VTABLE_CLONE(c) \
199+
_cloned_cpp_vtptrs[c##_Kind] = CppVtableCloner<c>::allocate(#c); \
200+
ArchivePtrMarker::mark_pointer(&_cloned_cpp_vtptrs[c##_Kind]);
201+
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#define CLONE_CPP_VTABLE(c) \
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p = CppVtableCloner<c>::clone_vtable(#c, (CppVtableInfo*)p);
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#define ZERO_CPP_VTABLE(c) \
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CppVtableCloner<c>::zero_vtable_clone();
207+
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#define INIT_ORIG_CPP_VTPTRS(c) \
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CppVtableCloner<c>::init_orig_cpp_vtptr(c##_Kind);
210+
211+
#define DECLARE_CLONED_VTABLE_KIND(c) c ## _Kind,
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enum ClonedVtableKind {
214+
// E.g., ConstantPool_Kind == 0, InstanceKlass_Kind == 1, etc.
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CPP_VTABLE_PATCH_TYPES_DO(DECLARE_CLONED_VTABLE_KIND)
216+
_num_cloned_vtable_kinds
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};
218+
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// This is a map of all the original vtptrs. E.g., for
220+
// ConstantPool *cp = new (...) ConstantPool(...) ; // a dynamically allocated constant pool
221+
// the following holds true:
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// _orig_cpp_vtptrs[ConstantPool_Kind] == ((intptr_t**)cp)[0]
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static intptr_t* _orig_cpp_vtptrs[_num_cloned_vtable_kinds];
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static bool _orig_cpp_vtptrs_inited = false;
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226+
template <class T>
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void CppVtableCloner<T>::init_orig_cpp_vtptr(int kind) {
228+
assert(kind < _num_cloned_vtable_kinds, "sanity");
229+
T tmp; // Allocate temporary dummy metadata object to get to the original vtable.
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intptr_t* srcvtable = vtable_of(&tmp);
231+
_orig_cpp_vtptrs[kind] = srcvtable;
232+
}
233+
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// This is the index of all the cloned vtables. E.g., for
235+
// ConstantPool* cp = ....; // an archived constant pool
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// InstanceKlass* ik = ....;// an archived class
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// the following holds true:
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// _cloned_cpp_vtptrs[ConstantPool_Kind] == ((intptr_t**)cp)[0]
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// _cloned_cpp_vtptrs[InstanceKlass_Kind] == ((intptr_t**)ik)[0]
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static intptr_t** _cloned_cpp_vtptrs = NULL;
241+
242+
void CppVtables::allocate_cloned_cpp_vtptrs() {
243+
assert(DumpSharedSpaces, "must");
244+
size_t vtptrs_bytes = _num_cloned_vtable_kinds * sizeof(intptr_t*);
245+
_cloned_cpp_vtptrs = (intptr_t**)mc_region()->allocate(vtptrs_bytes, sizeof(intptr_t*));
246+
}
247+
248+
void CppVtables::serialize_cloned_cpp_vtptrs(SerializeClosure* soc) {
249+
soc->do_ptr((void**)&_cloned_cpp_vtptrs);
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}
251+
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intptr_t* CppVtables::get_archived_cpp_vtable(MetaspaceObj::Type msotype, address obj) {
253+
if (!_orig_cpp_vtptrs_inited) {
254+
CPP_VTABLE_PATCH_TYPES_DO(INIT_ORIG_CPP_VTPTRS);
255+
_orig_cpp_vtptrs_inited = true;
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}
257+
258+
Arguments::assert_is_dumping_archive();
259+
int kind = -1;
260+
switch (msotype) {
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case MetaspaceObj::SymbolType:
262+
case MetaspaceObj::TypeArrayU1Type:
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case MetaspaceObj::TypeArrayU2Type:
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case MetaspaceObj::TypeArrayU4Type:
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case MetaspaceObj::TypeArrayU8Type:
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case MetaspaceObj::TypeArrayOtherType:
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case MetaspaceObj::ConstMethodType:
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case MetaspaceObj::ConstantPoolCacheType:
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case MetaspaceObj::AnnotationsType:
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case MetaspaceObj::MethodCountersType:
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case MetaspaceObj::RecordComponentType:
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// These have no vtables.
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break;
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case MetaspaceObj::MethodDataType:
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// We don't archive MethodData <-- should have been removed in removed_unsharable_info
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ShouldNotReachHere();
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break;
278+
default:
279+
for (kind = 0; kind < _num_cloned_vtable_kinds; kind ++) {
280+
if (vtable_of((Metadata*)obj) == _orig_cpp_vtptrs[kind]) {
281+
break;
282+
}
283+
}
284+
if (kind >= _num_cloned_vtable_kinds) {
285+
fatal("Cannot find C++ vtable for " INTPTR_FORMAT " -- you probably added"
286+
" a new subtype of Klass or MetaData without updating CPP_VTABLE_PATCH_TYPES_DO",
287+
p2i(obj));
288+
}
289+
}
290+
291+
if (kind >= 0) {
292+
assert(kind < _num_cloned_vtable_kinds, "must be");
293+
return _cloned_cpp_vtptrs[kind];
294+
} else {
295+
return NULL;
296+
}
297+
}
298+
299+
// This can be called at both dump time and run time:
300+
// - clone the contents of the c++ vtables into the space
301+
// allocated by allocate_cpp_vtable_clones()
302+
void CppVtables::clone_cpp_vtables(intptr_t* p) {
303+
assert(DumpSharedSpaces || UseSharedSpaces, "sanity");
304+
CPP_VTABLE_PATCH_TYPES_DO(CLONE_CPP_VTABLE);
305+
}
306+
307+
void CppVtables::zero_cpp_vtable_clones_for_writing() {
308+
assert(DumpSharedSpaces, "dump-time only");
309+
CPP_VTABLE_PATCH_TYPES_DO(ZERO_CPP_VTABLE);
310+
}
311+
312+
// Allocate and initialize the C++ vtables, starting from top, but do not go past end.
313+
char* CppVtables::allocate_cpp_vtable_clones() {
314+
char* cloned_vtables = mc_region()->top(); // This is the beginning of all the cloned vtables
315+
316+
assert(DumpSharedSpaces, "dump-time only");
317+
// Layout (each slot is a intptr_t):
318+
// [number of slots in the first vtable = n1]
319+
// [ <n1> slots for the first vtable]
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// [number of slots in the first second = n2]
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// [ <n2> slots for the second vtable]
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// ...
323+
// The order of the vtables is the same as the CPP_VTAB_PATCH_TYPES_DO macro.
324+
CPP_VTABLE_PATCH_TYPES_DO(ALLOC_CPP_VTABLE_CLONE);
325+
326+
return cloned_vtables;
327+
}
328+
329+
bool CppVtables::is_valid_shared_method(const Method* m) {
330+
assert(MetaspaceShared::is_in_shared_metaspace(m), "must be");
331+
return CppVtableCloner<Method>::is_valid_shared_object(m);
332+
}

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