Mercurial > hg > graal-jvmci-8
diff src/share/vm/memory/guardedMemory.hpp @ 20804:7848fc12602b
Merge with jdk8u40-b25
author | Gilles Duboscq <gilles.m.duboscq@oracle.com> |
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date | Tue, 07 Apr 2015 14:58:49 +0200 |
parents | fa62fb12cdca |
children | d68158e12cea |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/memory/guardedMemory.hpp Tue Apr 07 14:58:49 2015 +0200 @@ -0,0 +1,326 @@ +/* + * Copyright (c) 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_VM_MEMORY_GUARDED_MEMORY_HPP +#define SHARE_VM_MEMORY_GUARDED_MEMORY_HPP + +#include "memory/allocation.hpp" +#include "utilities/globalDefinitions.hpp" + +/** + * Guarded memory for detecting buffer overrun. + * + * Allows allocations to be wrapped with padded bytes of a known byte pattern, + * that is a "guard". Guard patterns may be verified to detect buffer overruns. + * + * Primarily used by "debug malloc" and "checked JNI". + * + * Memory layout: + * + * |Offset | Content | Description | + * |------------------------------------------------------------ + * |base_addr | 0xABABABABABABABAB | Head guard | + * |+16 | <size_t:user_size> | User data size | + * |+sizeof(uintptr_t) | <tag> | Tag word | + * |+sizeof(void*) | 0xF1 <user_data> ( | User data | + * |+user_size | 0xABABABABABABABAB | Tail guard | + * ------------------------------------------------------------- + * + * Where: + * - guard padding uses "badResourceValue" (0xAB) + * - tag word is general purpose + * - user data + * -- initially padded with "uninitBlockPad" (0xF1), + * -- to "freeBlockPad" (0xBA), when freed + * + * Usage: + * + * * Allocations: one may wrap allocations with guard memory: + * <code> + * Thing* alloc_thing() { + * void* mem = user_alloc_fn(GuardedMemory::get_total_size(sizeof(thing))); + * GuardedMemory guarded(mem, sizeof(thing)); + * return (Thing*) guarded.get_user_ptr(); + * } + * </code> + * * Verify: memory guards are still in tact + * <code> + * bool verify_thing(Thing* thing) { + * GuardedMemory guarded((void*)thing); + * return guarded.verify_guards(); + * } + * </code> + * * Free: one may mark bytes as freed (further debugging support) + * <code> + * void free_thing(Thing* thing) { + * GuardedMemory guarded((void*)thing); + * assert(guarded.verify_guards(), "Corrupt thing"); + * user_free_fn(guards.release_for_freeing(); + * } + * </code> + */ +class GuardedMemory : StackObj { // Wrapper on stack + + // Private inner classes for memory layout... + +protected: + + /** + * Guard class for header and trailer known pattern to test for overwrites. + */ + class Guard { // Class for raw memory (no vtbl allowed) + friend class GuardedMemory; + protected: + enum { + GUARD_SIZE = 16 + }; + + u_char _guard[GUARD_SIZE]; + + public: + + void build() { + u_char* c = _guard; // Possibly unaligned if tail guard + u_char* end = c + GUARD_SIZE; + while (c < end) { + *c = badResourceValue; + c++; + } + } + + bool verify() const { + u_char* c = (u_char*) _guard; + u_char* end = c + GUARD_SIZE; + while (c < end) { + if (*c != badResourceValue) { + return false; + } + c++; + } + return true; + } + + }; // GuardedMemory::Guard + + /** + * Header guard and size + */ + class GuardHeader : Guard { + friend class GuardedMemory; + protected: + // Take care in modifying fields here, will effect alignment + // e.g. x86 ABI 16 byte stack alignment + union { + uintptr_t __unused_full_word1; + size_t _user_size; + }; + void* _tag; + public: + void set_user_size(const size_t usz) { _user_size = usz; } + size_t get_user_size() const { return _user_size; } + + void set_tag(const void* tag) { _tag = (void*) tag; } + void* get_tag() const { return _tag; } + + }; // GuardedMemory::GuardHeader + + // Guarded Memory... + + protected: + u_char* _base_addr; + + public: + + /** + * Create new guarded memory. + * + * Wraps, starting at the given "base_ptr" with guards. Use "get_user_ptr()" + * to return a pointer suitable for user data. + * + * @param base_ptr allocation wishing to be wrapped, must be at least "GuardedMemory::get_total_size()" bytes. + * @param user_size the size of the user data to be wrapped. + * @param tag optional general purpose tag. + */ + GuardedMemory(void* base_ptr, const size_t user_size, const void* tag = NULL) { + wrap_with_guards(base_ptr, user_size, tag); + } + + /** + * Wrap existing guarded memory. + * + * To use this constructor, one must have created guarded memory with + * "GuardedMemory(void*, size_t, void*)" (or indirectly via helper, e.g. "wrap_copy()"). + * + * @param user_p existing wrapped memory. + */ + GuardedMemory(void* userp) { + u_char* user_ptr = (u_char*) userp; + assert((uintptr_t)user_ptr > (sizeof(GuardHeader) + 0x1000), "Invalid pointer"); + _base_addr = (user_ptr - sizeof(GuardHeader)); + } + + /** + * Create new guarded memory. + * + * Wraps, starting at the given "base_ptr" with guards. Allows reuse of stack allocated helper. + * + * @param base_ptr allocation wishing to be wrapped, must be at least "GuardedMemory::get_total_size()" bytes. + * @param user_size the size of the user data to be wrapped. + * @param tag optional general purpose tag. + * + * @return user data pointer (inner pointer to supplied "base_ptr"). + */ + void* wrap_with_guards(void* base_ptr, size_t user_size, const void* tag = NULL) { + assert(base_ptr != NULL, "Attempt to wrap NULL with memory guard"); + _base_addr = (u_char*)base_ptr; + get_head_guard()->build(); + get_head_guard()->set_user_size(user_size); + get_tail_guard()->build(); + set_tag(tag); + set_user_bytes(uninitBlockPad); + assert(verify_guards(), "Expected valid memory guards"); + return get_user_ptr(); + } + + /** + * Verify head and tail guards. + * + * @return true if guards are intact, false would indicate a buffer overrun. + */ + bool verify_guards() const { + if (_base_addr != NULL) { + return (get_head_guard()->verify() && get_tail_guard()->verify()); + } + return false; + } + + /** + * Set the general purpose tag. + * + * @param tag general purpose tag. + */ + void set_tag(const void* tag) { get_head_guard()->set_tag(tag); } + + /** + * Return the general purpose tag. + * + * @return the general purpose tag, defaults to NULL. + */ + void* get_tag() const { return get_head_guard()->get_tag(); } + + /** + * Return the size of the user data. + * + * @return the size of the user data. + */ + size_t get_user_size() const { + assert(_base_addr, "Not wrapping any memory"); + return get_head_guard()->get_user_size(); + } + + /** + * Return the user data pointer. + * + * @return the user data pointer. + */ + u_char* get_user_ptr() const { + assert(_base_addr, "Not wrapping any memory"); + return _base_addr + sizeof(GuardHeader); + } + + /** + * Release the wrapped pointer for resource freeing. + * + * Pads the user data with "freeBlockPad", and dis-associates the helper. + * + * @return the original base pointer used to wrap the data. + */ + void* release_for_freeing() { + set_user_bytes(freeBlockPad); + return release(); + } + + /** + * Dis-associate the help from the original base address. + * + * @return the original base pointer used to wrap the data. + */ + void* release() { + void* p = (void*) _base_addr; + _base_addr = NULL; + return p; + } + + virtual void print_on(outputStream* st) const; + + protected: + GuardHeader* get_head_guard() const { return (GuardHeader*) _base_addr; } + Guard* get_tail_guard() const { return (Guard*) (get_user_ptr() + get_user_size()); }; + void set_user_bytes(u_char ch) { + memset(get_user_ptr(), ch, get_user_size()); + } + +public: + /** + * Return the total size required for wrapping the given user size. + * + * @return the total size required for wrapping the given user size. + */ + static size_t get_total_size(size_t user_size) { + size_t total_size = sizeof(GuardHeader) + user_size + sizeof(Guard); + assert(total_size > user_size, "Unexpected wrap-around"); + return total_size; + } + + // Helper functions... + + /** + * Wrap a copy of size "len" of "ptr". + * + * @param ptr the memory to be copied + * @param len the length of the copy + * @param tag optional general purpose tag (see GuardedMemory::get_tag()) + * + * @return guarded wrapped memory pointer to the user area, or NULL if OOM. + */ + static void* wrap_copy(const void* p, const size_t len, const void* tag = NULL); + + /** + * Free wrapped copy. + * + * Frees memory copied with "wrap_copy()". + * + * @param p memory returned by "wrap_copy()". + * + * @return true if guards were verified as intact. false indicates a buffer overrun. + */ + static bool free_copy(void* p); + + // Testing... +#ifndef PRODUCT + static void test_guarded_memory(void); +#endif +}; // GuardedMemory + +#endif // SHARE_VM_MEMORY_GUARDED_MEMORY_HPP