jdk8-mips64-public/hotspot: src/share/vm/prims/jvmtiRedefineClasses.hpp@f008d3631bd1 (annotated)

src/share/vm/prims/jvmtiRedefineClasses.hpp@f008d3631bd1 (annotated)

src/share/vm/prims/jvmtiRedefineClasses.hpp

Wed, 08 Oct 2008 08:10:51 -0700

author: ksrini
date: Wed, 08 Oct 2008 08:10:51 -0700
changeset 823: f008d3631bd1
parent 435: a61af66fc99e
child 1907: c18cbe5936b8
permissions: -rw-r--r--

6755845: JVM_FindClassFromBoot triggers assertions
Summary: Fixes assertions caused by one jvm_entry calling another, solved by refactoring code and modified gamma test.
Reviewed-by: dholmes, xlu

 /*
  * Copyright 2003-2006 Sun Microsystems, Inc.  All Rights Reserved.
  * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 // Introduction:
 //
 // The RedefineClasses() API is used to change the definition of one or
 // more classes. While the API supports redefining more than one class
 // in a single call, in general, the API is discussed in the context of
 // changing the definition of a single current class to a single new
 // class. For clarity, the current class is will always be called
 // "the_class" and the new class will always be called "scratch_class".
 //
 // The name "the_class" is used because there is only one structure
 // that represents a specific class; redefinition does not replace the
 // structure, but instead replaces parts of the structure. The name
 // "scratch_class" is used because the structure that represents the
 // new definition of a specific class is simply used to carry around
 // the parts of the new definition until they are used to replace the
 // appropriate parts in the_class. Once redefinition of a class is
 // complete, scratch_class is thrown away.
 //
 //
 // Implementation Overview:
 //
 // The RedefineClasses() API is mostly a wrapper around the VM op that
 // does the real work. The work is split in varying degrees between
 // doit_prologue(), doit() and doit_epilogue().
 //
 // 1) doit_prologue() is called by the JavaThread on the way to a
 //    safepoint. It does parameter verification and loads scratch_class
 //    which involves:
 //    - parsing the incoming class definition using the_class' class
 //      loader and security context
 //    - linking scratch_class
 //    - merging constant pools and rewriting bytecodes as needed
 //      for the merged constant pool
 //    - verifying the bytecodes in scratch_class
 //    - setting up the constant pool cache and rewriting bytecodes
 //      as needed to use the cache
 //    - finally, scratch_class is compared to the_class to verify
 //      that it is a valid replacement class
 //    - if everything is good, then scratch_class is saved in an
 //      instance field in the VM operation for the doit() call
 //
 //    Note: A JavaThread must do the above work.
 //
 // 2) doit() is called by the VMThread during a safepoint. It installs
 //    the new class definition(s) which involves:
 //    - retrieving the scratch_class from the instance field in the
 //      VM operation
 //    - house keeping (flushing breakpoints and caches, deoptimizing
 //      dependent compiled code)
 //    - replacing parts in the_class with parts from scratch_class
 //    - adding weak reference(s) to track the obsolete but interesting
 //      parts of the_class
 //    - adjusting constant pool caches and vtables in other classes
 //      that refer to methods in the_class. These adjustments use the
 //      SystemDictionary::classes_do() facility which only allows
 //      a helper method to be specified. The interesting parameters
 //      that we would like to pass to the helper method are saved in
 //      static global fields in the VM operation.
 //    - telling the SystemDictionary to notice our changes
 //
 //    Note: the above work must be done by the VMThread to be safe.
 //
 // 3) doit_epilogue() is called by the JavaThread after the VM op
 //    is finished and the safepoint is done. It simply cleans up
 //    memory allocated in doit_prologue() and used in doit().
 //
 //
 // Constant Pool Details:
 //
 // When the_class is redefined, we cannot just replace the constant
 // pool in the_class with the constant pool from scratch_class because
 // that could confuse obsolete methods that may still be running.
 // Instead, the constant pool from the_class, old_cp, is merged with
 // the constant pool from scratch_class, scratch_cp. The resulting
 // constant pool, merge_cp, replaces old_cp in the_class.
 //
 // The key part of any merging algorithm is the entry comparison
 // function so we have to know the types of entries in a constant pool
 // in order to merge two of them together. Constant pools can contain
 // up to 12 different kinds of entries; the JVM_CONSTANT_Unicode entry
 // is not presently used so we only have to worry about the other 11
 // entry types. For the purposes of constant pool merging, it is
 // helpful to know that the 11 entry types fall into 3 different
 // subtypes: "direct", "indirect" and "double-indirect".
 //
 // Direct CP entries contain data and do not contain references to
 // other CP entries. The following are direct CP entries:
 //     JVM_CONSTANT_{Double,Float,Integer,Long,Utf8}
 //
 // Indirect CP entries contain 1 or 2 references to a direct CP entry
 // and no other data. The following are indirect CP entries:
 //     JVM_CONSTANT_{Class,NameAndType,String}
 //
 // Double-indirect CP entries contain two references to indirect CP
 // entries and no other data. The following are double-indirect CP
 // entries:
 //     JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref}
 //
 // When comparing entries between two constant pools, the entry types
 // are compared first and if they match, then further comparisons are
 // made depending on the entry subtype. Comparing direct CP entries is
 // simply a matter of comparing the data associated with each entry.
 // Comparing both indirect and double-indirect CP entries requires
 // recursion.
 //
 // Fortunately, the recursive combinations are limited because indirect
 // CP entries can only refer to direct CP entries and double-indirect
 // CP entries can only refer to indirect CP entries. The following is
 // an example illustration of the deepest set of indirections needed to
 // access the data associated with a JVM_CONSTANT_Fieldref entry:
 //
 //     JVM_CONSTANT_Fieldref {
 //         class_index => JVM_CONSTANT_Class {
 //             name_index => JVM_CONSTANT_Utf8 {
 //                 <data-1>
 //             }
 //         }
 //         name_and_type_index => JVM_CONSTANT_NameAndType {
 //             name_index => JVM_CONSTANT_Utf8 {
 //                 <data-2>
 //             }
 //             descriptor_index => JVM_CONSTANT_Utf8 {
 //                 <data-3>
 //             }
 //         }
 //     }
 //
 // The above illustration is not a data structure definition for any
 // computer language. The curly braces ('{' and '}') are meant to
 // delimit the context of the "fields" in the CP entry types shown.
 // Each indirection from the JVM_CONSTANT_Fieldref entry is shown via
 // "=>", e.g., the class_index is used to indirectly reference a
 // JVM_CONSTANT_Class entry where the name_index is used to indirectly
 // reference a JVM_CONSTANT_Utf8 entry which contains the interesting
 // <data-1>. In order to understand a JVM_CONSTANT_Fieldref entry, we
 // have to do a total of 5 indirections just to get to the CP entries
 // that contain the interesting pieces of data and then we have to
 // fetch the three pieces of data. This means we have to do a total of
 // (5 + 3) * 2 == 16 dereferences to compare two JVM_CONSTANT_Fieldref
 // entries.
 //
 // Here is the indirection, data and dereference count for each entry
 // type:
 //
 //    JVM_CONSTANT_Class               1 indir, 1 data, 2 derefs
 //    JVM_CONSTANT_Double              0 indir, 1 data, 1 deref
 //    JVM_CONSTANT_Fieldref            2 indir, 3 data, 8 derefs
 //    JVM_CONSTANT_Float               0 indir, 1 data, 1 deref
 //    JVM_CONSTANT_Integer             0 indir, 1 data, 1 deref
 //    JVM_CONSTANT_InterfaceMethodref  2 indir, 3 data, 8 derefs
 //    JVM_CONSTANT_Long                0 indir, 1 data, 1 deref
 //    JVM_CONSTANT_Methodref           2 indir, 3 data, 8 derefs
 //    JVM_CONSTANT_NameAndType         1 indir, 2 data, 4 derefs
 //    JVM_CONSTANT_String              1 indir, 1 data, 2 derefs
 //    JVM_CONSTANT_Utf8                0 indir, 1 data, 1 deref
 //
 // So different subtypes of CP entries require different amounts of
 // work for a proper comparison.
 //
 // Now that we've talked about the different entry types and how to
 // compare them we need to get back to merging. This is not a merge in
 // the "sort -u" sense or even in the "sort" sense. When we merge two
 // constant pools, we copy all the entries from old_cp to merge_cp,
 // preserving entry order. Next we append all the unique entries from
 // scratch_cp to merge_cp and we track the index changes from the
 // location in scratch_cp to the possibly new location in merge_cp.
 // When we are done, any obsolete code that is still running that
 // uses old_cp should not be able to observe any difference if it
 // were to use merge_cp. As for the new code in scratch_class, it is
 // modified to use the appropriate index values in merge_cp before it
 // is used to replace the code in the_class.
 //
 // There is one small complication in copying the entries from old_cp
 // to merge_cp. Two of the CP entry types are special in that they are
 // lazily resolved. Before explaining the copying complication, we need
 // to digress into CP entry resolution.
 //
 // JVM_CONSTANT_Class and JVM_CONSTANT_String entries are present in
 // the class file, but are not stored in memory as such until they are
 // resolved. The entries are not resolved unless they are used because
 // resolution is expensive. During class file parsing the entries are
 // initially stored in memory as JVM_CONSTANT_ClassIndex and
 // JVM_CONSTANT_StringIndex entries. These special CP entry types
 // indicate that the JVM_CONSTANT_Class and JVM_CONSTANT_String entries
 // have been parsed, but the index values in the entries have not been
 // validated. After the entire constant pool has been parsed, the index
 // values can be validated and then the entries are converted into
 // JVM_CONSTANT_UnresolvedClass and JVM_CONSTANT_UnresolvedString
 // entries. During this conversion process, the UTF8 values that are
 // indirectly referenced by the JVM_CONSTANT_ClassIndex and
 // JVM_CONSTANT_StringIndex entries are changed into symbolOops and the
 // entries are modified to refer to the symbolOops. This optimization
 // eliminates one level of indirection for those two CP entry types and
 // gets the entries ready for verification. During class file parsing
 // it is also possible for JVM_CONSTANT_UnresolvedString entries to be
 // resolved into JVM_CONSTANT_String entries. Verification expects to
 // find JVM_CONSTANT_UnresolvedClass and either JVM_CONSTANT_String or
 // JVM_CONSTANT_UnresolvedString entries and not JVM_CONSTANT_Class
 // entries.
 //
 // Now we can get back to the copying complication. When we copy
 // entries from old_cp to merge_cp, we have to revert any
 // JVM_CONSTANT_Class entries to JVM_CONSTANT_UnresolvedClass entries
 // or verification will fail.
 //
 // It is important to explicitly state that the merging algorithm
 // effectively unresolves JVM_CONSTANT_Class entries that were in the
 // old_cp when they are changed into JVM_CONSTANT_UnresolvedClass
 // entries in the merge_cp. This is done both to make verification
 // happy and to avoid adding more brittleness between RedefineClasses
 // and the constant pool cache. By allowing the constant pool cache
 // implementation to (re)resolve JVM_CONSTANT_UnresolvedClass entries
 // into JVM_CONSTANT_Class entries, we avoid having to embed knowledge
 // about those algorithms in RedefineClasses.
 //
 // Appending unique entries from scratch_cp to merge_cp is straight
 // forward for direct CP entries and most indirect CP entries. For the
 // indirect CP entry type JVM_CONSTANT_NameAndType and for the double-
 // indirect CP entry types, the presence of more than one piece of
 // interesting data makes appending the entries more complicated.
 //
 // For the JVM_CONSTANT_{Double,Float,Integer,Long,Utf8} entry types,
 // the entry is simply copied from scratch_cp to the end of merge_cp.
 // If the index in scratch_cp is different than the destination index
 // in merge_cp, then the change in index value is tracked.
 //
 // Note: the above discussion for the direct CP entries also applies
 // to the JVM_CONSTANT_Unresolved{Class,String} entry types.
 //
 // For the JVM_CONSTANT_{Class,String} entry types, since there is only
 // one data element at the end of the recursion, we know that we have
 // either one or two unique entries. If the JVM_CONSTANT_Utf8 entry is
 // unique then it is appended to merge_cp before the current entry.
 // If the JVM_CONSTANT_Utf8 entry is not unique, then the current entry
 // is updated to refer to the duplicate entry in merge_cp before it is
 // appended to merge_cp. Again, any changes in index values are tracked
 // as needed.
 //
 // Note: the above discussion for JVM_CONSTANT_{Class,String} entry
 // types is theoretical. Since those entry types have already been
 // optimized into JVM_CONSTANT_Unresolved{Class,String} entry types,
 // they are handled as direct CP entries.
 //
 // For the JVM_CONSTANT_NameAndType entry type, since there are two
 // data elements at the end of the recursions, we know that we have
 // between one and three unique entries. Any unique JVM_CONSTANT_Utf8
 // entries are appended to merge_cp before the current entry. For any
 // JVM_CONSTANT_Utf8 entries that are not unique, the current entry is
 // updated to refer to the duplicate entry in merge_cp before it is
 // appended to merge_cp. Again, any changes in index values are tracked
 // as needed.
 //
 // For the JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref} entry
 // types, since there are two indirect CP entries and three data
 // elements at the end of the recursions, we know that we have between
 // one and six unique entries. See the JVM_CONSTANT_Fieldref diagram
 // above for an example of all six entries. The uniqueness algorithm
 // for the JVM_CONSTANT_Class and JVM_CONSTANT_NameAndType entries is
 // covered above. Any unique entries are appended to merge_cp before
 // the current entry. For any entries that are not unique, the current
 // entry is updated to refer to the duplicate entry in merge_cp before
 // it is appended to merge_cp. Again, any changes in index values are
 // tracked as needed.
 //
 //
 // Other Details:
 //
 // Details for other parts of RedefineClasses need to be written.
 // This is a placeholder section.
 //
 //
 // Open Issues (in no particular order):
 //
 // - How do we serialize the RedefineClasses() API without deadlocking?
 //
 // - SystemDictionary::parse_stream() was called with a NULL protection
 //   domain since the initial version. This has been changed to pass
 //   the_class->protection_domain(). This change has been tested with
 //   all NSK tests and nothing broke, but what will adding it now break
 //   in ways that we don't test?
 //
 // - GenerateOopMap::rewrite_load_or_store() has a comment in its
 //   (indirect) use of the Relocator class that the max instruction
 //   size is 4 bytes. goto_w and jsr_w are 5 bytes and wide/iinc is
 //   6 bytes. Perhaps Relocator only needs a 4 byte buffer to do
 //   what it does to the bytecodes. More investigation is needed.
 //
 // - java.lang.Object methods can be called on arrays. This is
 //   implemented via the arrayKlassOop vtable which we don't
 //   update. For example, if we redefine java.lang.Object.toString(),
 //   then the new version of the method will not be called for array
 //   objects.
 //
 // - How do we know if redefine_single_class() and the guts of
 //   instanceKlass are out of sync? I don't think this can be
 //   automated, but we should probably order the work in
 //   redefine_single_class() to match the order of field
 //   definitions in instanceKlass. We also need to add some
 //   comments about keeping things in sync.
 //
 // - set_new_constant_pool() is huge and we should consider refactoring
 //   it into smaller chunks of work.
 //
 // - The exception table update code in set_new_constant_pool() defines
 //   const values that are also defined in a local context elsewhere.
 //   The same literal values are also used in elsewhere. We need to
 //   coordinate a cleanup of these constants with Runtime.
 //
 class VM_RedefineClasses: public VM_Operation {
  private:
   // These static fields are needed by SystemDictionary::classes_do()
   // facility and the adjust_cpool_cache_and_vtable() helper:
   static objArrayOop     _old_methods;
   static objArrayOop     _new_methods;
   static methodOop*      _matching_old_methods;
   static methodOop*      _matching_new_methods;
   static methodOop*      _deleted_methods;
   static methodOop*      _added_methods;
   static int             _matching_methods_length;
   static int             _deleted_methods_length;
   static int             _added_methods_length;
   static klassOop        _the_class_oop;
   // The instance fields are used to pass information from
   // doit_prologue() to doit() and doit_epilogue().
   jint                        _class_count;
   const jvmtiClassDefinition *_class_defs;  // ptr to _class_count defs
   // This operation is used by both RedefineClasses and
   // RetransformClasses.  Indicate which.
   JvmtiClassLoadKind          _class_load_kind;
   // _index_map_count is just an optimization for knowing if
   // _index_map_p contains any entries.
   int                         _index_map_count;
   intArray *                  _index_map_p;
   // ptr to _class_count scratch_classes
   instanceKlassHandle *       _scratch_classes;
   jvmtiError                  _res;
   // Performance measurement support. These timers do not cover all
   // the work done for JVM/TI RedefineClasses() but they do cover
   // the heavy lifting.
   elapsedTimer  _timer_rsc_phase1;
   elapsedTimer  _timer_rsc_phase2;
   elapsedTimer  _timer_vm_op_prologue;
   // These routines are roughly in call order unless otherwise noted.
   // Load the caller's new class definition(s) into _scratch_classes.
   // Constant pool merging work is done here as needed. Also calls
   // compare_and_normalize_class_versions() to verify the class
   // definition(s).
   jvmtiError load_new_class_versions(TRAPS);
   // Verify that the caller provided class definition(s) that meet
   // the restrictions of RedefineClasses. Normalize the order of
   // overloaded methods as needed.
   jvmtiError compare_and_normalize_class_versions(
     instanceKlassHandle the_class, instanceKlassHandle scratch_class);
   // Swap annotations[i] with annotations[j]
   // Used by compare_and_normalize_class_versions() when normalizing
   // overloaded methods or changing idnum as when adding or deleting methods.
   void swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class);
   // Figure out which new methods match old methods in name and signature,
   // which methods have been added, and which are no longer present
   void compute_added_deleted_matching_methods();
   // Change jmethodIDs to point to the new methods
   void update_jmethod_ids();
   // In addition to marking methods as obsolete, this routine
   // records which methods are EMCP (Equivalent Module Constant
   // Pool) in the emcp_methods BitMap and returns the number of
   // EMCP methods via emcp_method_count_p. This information is
   // used when information about the previous version of the_class
   // is squirreled away.
   void check_methods_and_mark_as_obsolete(BitMap *emcp_methods,
          int * emcp_method_count_p);
   void transfer_old_native_function_registrations(instanceKlassHandle the_class);
   // Unevolving classes may point to methods of the_class directly
   // from their constant pool caches, itables, and/or vtables. We
   // use the SystemDictionary::classes_do() facility and this helper
   // to fix up these pointers.
   static void adjust_cpool_cache_and_vtable(klassOop k_oop, oop loader, TRAPS);
   // Install the redefinition of a class
   void redefine_single_class(jclass the_jclass,
     instanceKlassHandle scratch_class, TRAPS);
   // Increment the classRedefinedCount field in the specific instanceKlass
   // and in all direct and indirect subclasses.
   void increment_class_counter(instanceKlass *ik, TRAPS);
   // Support for constant pool merging (these routines are in alpha
   // order):
   void append_entry(constantPoolHandle scratch_cp, int scratch_i,
     constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
   int find_new_index(int old_index);
   bool is_unresolved_class_mismatch(constantPoolHandle cp1, int index1,
     constantPoolHandle cp2, int index2);
   bool is_unresolved_string_mismatch(constantPoolHandle cp1, int index1,
     constantPoolHandle cp2, int index2);
   void map_index(constantPoolHandle scratch_cp, int old_index, int new_index);
   bool merge_constant_pools(constantPoolHandle old_cp,
     constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
     int *merge_cp_length_p, TRAPS);
   jvmtiError merge_cp_and_rewrite(instanceKlassHandle the_class,
     instanceKlassHandle scratch_class, TRAPS);
   u2 rewrite_cp_ref_in_annotation_data(
     typeArrayHandle annotations_typeArray, int &byte_i_ref,
     const char * trace_mesg, TRAPS);
   bool rewrite_cp_refs(instanceKlassHandle scratch_class, TRAPS);
   bool rewrite_cp_refs_in_annotation_struct(
     typeArrayHandle class_annotations, int &byte_i_ref, TRAPS);
   bool rewrite_cp_refs_in_annotations_typeArray(
     typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS);
   bool rewrite_cp_refs_in_class_annotations(
     instanceKlassHandle scratch_class, TRAPS);
   bool rewrite_cp_refs_in_element_value(
     typeArrayHandle class_annotations, int &byte_i_ref, TRAPS);
   bool rewrite_cp_refs_in_fields_annotations(
     instanceKlassHandle scratch_class, TRAPS);
   void rewrite_cp_refs_in_method(methodHandle method,
     methodHandle * new_method_p, TRAPS);
   bool rewrite_cp_refs_in_methods(instanceKlassHandle scratch_class, TRAPS);
   bool rewrite_cp_refs_in_methods_annotations(
     instanceKlassHandle scratch_class, TRAPS);
   bool rewrite_cp_refs_in_methods_default_annotations(
     instanceKlassHandle scratch_class, TRAPS);
   bool rewrite_cp_refs_in_methods_parameter_annotations(
     instanceKlassHandle scratch_class, TRAPS);
   void rewrite_cp_refs_in_stack_map_table(methodHandle method, TRAPS);
   void rewrite_cp_refs_in_verification_type_info(
          address& stackmap_addr_ref, address stackmap_end, u2 frame_i,
          u1 frame_size, TRAPS);
   void set_new_constant_pool(instanceKlassHandle scratch_class,
     constantPoolHandle scratch_cp, int scratch_cp_length, bool shrink, TRAPS);
   void flush_dependent_code(instanceKlassHandle k_h, TRAPS);
   static void check_class(klassOop k_oop, oop initiating_loader, TRAPS) PRODUCT_RETURN;
   static void dump_methods()   PRODUCT_RETURN;
  public:
   VM_RedefineClasses(jint class_count,
                      const jvmtiClassDefinition *class_defs,
                      JvmtiClassLoadKind class_load_kind);
   VMOp_Type type() const { return VMOp_RedefineClasses; }
   bool doit_prologue();
   void doit();
   void doit_epilogue();
   bool allow_nested_vm_operations() const        { return true; }
   jvmtiError check_error()                       { return _res; }
   // Modifiable test must be shared between IsModifiableClass query
   // and redefine implementation
   static bool is_modifiable_class(oop klass_mirror);
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/prims/jvmtiRedefineClasses.hpp@f008d3631bd1 (annotated)

src/share/vm/prims/jvmtiRedefineClasses.hpp