jdk8-mips64-public/hotspot: src/share/vm/utilities/copy.cpp@dee6a1ce4a0c (annotated)

src/share/vm/utilities/copy.cpp@dee6a1ce4a0c (annotated)

src/share/vm/utilities/copy.cpp

Mon, 03 Dec 2018 07:29:54 -0500

author: dbuck
date: Mon, 03 Dec 2018 07:29:54 -0500
changeset 9562: dee6a1ce4a0c
parent 2314: f95d63e2154a
child 9572: 624a0741915c
permissions: -rw-r--r--

8141491: Unaligned memory access in Bits.c
Summary: Introduce alignment-safe Copy::conjoint_swap and JVM_CopySwapMemory
Reviewed-by: mikael, dholmes

 /*
  * Copyright (c) 2006, 2018, 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.
  *
  */
 #include "precompiled.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "utilities/copy.hpp"
 // Copy bytes; larger units are filled atomically if everything is aligned.
 void Copy::conjoint_memory_atomic(void* from, void* to, size_t size) {
   address src = (address) from;
   address dst = (address) to;
   uintptr_t bits = (uintptr_t) src | (uintptr_t) dst | (uintptr_t) size;
   // (Note:  We could improve performance by ignoring the low bits of size,
   // and putting a short cleanup loop after each bulk copy loop.
   // There are plenty of other ways to make this faster also,
   // and it's a slippery slope.  For now, let's keep this code simple
   // since the simplicity helps clarify the atomicity semantics of
   // this operation.  There are also CPU-specific assembly versions
   // which may or may not want to include such optimizations.)
   if (bits % sizeof(jlong) == 0) {
     Copy::conjoint_jlongs_atomic((jlong*) src, (jlong*) dst, size / sizeof(jlong));
   } else if (bits % sizeof(jint) == 0) {
     Copy::conjoint_jints_atomic((jint*) src, (jint*) dst, size / sizeof(jint));
   } else if (bits % sizeof(jshort) == 0) {
     Copy::conjoint_jshorts_atomic((jshort*) src, (jshort*) dst, size / sizeof(jshort));
   } else {
     // Not aligned, so no need to be atomic.
     Copy::conjoint_jbytes((void*) src, (void*) dst, size);
   }
 }
 class CopySwap : AllStatic {
 public:
   /**
    * Copy and byte swap elements
    *
    * @param src address of source
    * @param dst address of destination
    * @param byte_count number of bytes to copy
    * @param elem_size size of the elements to copy-swap
    */
   static void conjoint_swap(address src, address dst, size_t byte_count, size_t elem_size) {
     assert(src != NULL, "address must not be NULL");
     assert(dst != NULL, "address must not be NULL");
     assert(elem_size == 2 || elem_size == 4 || elem_size == 8,
            err_msg("incorrect element size: " SIZE_FORMAT, elem_size));
     assert(is_size_aligned(byte_count, elem_size),
            err_msg("byte_count " SIZE_FORMAT " must be multiple of element size " SIZE_FORMAT, byte_count, elem_size));
     address src_end = src + byte_count;
     if (dst <= src || dst >= src_end) {
       do_conjoint_swap<RIGHT>(src, dst, byte_count, elem_size);
     } else {
       do_conjoint_swap<LEFT>(src, dst, byte_count, elem_size);
     }
   }
 private:
   /**
    * Byte swap a 16-bit value
    */
   static uint16_t byte_swap(uint16_t x) {
     return (x << 8) | (x >> 8);
   }
   /**
    * Byte swap a 32-bit value
    */
   static uint32_t byte_swap(uint32_t x) {
     uint16_t lo = (uint16_t)x;
     uint16_t hi = (uint16_t)(x >> 16);
     return ((uint32_t)byte_swap(lo) << 16) | (uint32_t)byte_swap(hi);
   }
   /**
    * Byte swap a 64-bit value
    */
   static uint64_t byte_swap(uint64_t x) {
     uint32_t lo = (uint32_t)x;
     uint32_t hi = (uint32_t)(x >> 32);
     return ((uint64_t)byte_swap(lo) << 32) | (uint64_t)byte_swap(hi);
   }
   enum CopyDirection {
     RIGHT, // lower -> higher address
     LEFT   // higher -> lower address
   };
   /**
    * Copy and byte swap elements
    *
    * <T> - type of element to copy
    * <D> - copy direction
    * <is_src_aligned> - true if src argument is aligned to element size
    * <is_dst_aligned> - true if dst argument is aligned to element size
    *
    * @param src address of source
    * @param dst address of destination
    * @param byte_count number of bytes to copy
    */
   template <typename T, CopyDirection D, bool is_src_aligned, bool is_dst_aligned>
   static void do_conjoint_swap(address src, address dst, size_t byte_count) {
     address cur_src, cur_dst;
     switch (D) {
     case RIGHT:
       cur_src = src;
       cur_dst = dst;
       break;
     case LEFT:
       cur_src = src + byte_count - sizeof(T);
       cur_dst = dst + byte_count - sizeof(T);
       break;
     }
     for (size_t i = 0; i < byte_count / sizeof(T); i++) {
       T tmp;
       if (is_src_aligned) {
         tmp = *(T*)cur_src;
       } else {
         memcpy(&tmp, cur_src, sizeof(T));
       }
       tmp = byte_swap(tmp);
       if (is_dst_aligned) {
         *(T*)cur_dst = tmp;
       } else {
         memcpy(cur_dst, &tmp, sizeof(T));
       }
       switch (D) {
       case RIGHT:
         cur_src += sizeof(T);
         cur_dst += sizeof(T);
         break;
       case LEFT:
         cur_src -= sizeof(T);
         cur_dst -= sizeof(T);
         break;
       }
     }
   }
   /**
    * Copy and byte swap elements
    *
    * <T> - type of element to copy
    * <D> - copy direction
    *
    * @param src address of source
    * @param dst address of destination
    * @param byte_count number of bytes to copy
    */
   template <typename T, CopyDirection direction>
   static void do_conjoint_swap(address src, address dst, size_t byte_count) {
     if (is_ptr_aligned(src, sizeof(T))) {
       if (is_ptr_aligned(dst, sizeof(T))) {
         do_conjoint_swap<T,direction,true,true>(src, dst, byte_count);
       } else {
         do_conjoint_swap<T,direction,true,false>(src, dst, byte_count);
       }
     } else {
       if (is_ptr_aligned(dst, sizeof(T))) {
         do_conjoint_swap<T,direction,false,true>(src, dst, byte_count);
       } else {
         do_conjoint_swap<T,direction,false,false>(src, dst, byte_count);
       }
     }
   }
   /**
    * Copy and byte swap elements
    *
    * <D> - copy direction
    *
    * @param src address of source
    * @param dst address of destination
    * @param byte_count number of bytes to copy
    * @param elem_size size of the elements to copy-swap
    */
   template <CopyDirection D>
   static void do_conjoint_swap(address src, address dst, size_t byte_count, size_t elem_size) {
     switch (elem_size) {
     case 2: do_conjoint_swap<uint16_t,D>(src, dst, byte_count); break;
     case 4: do_conjoint_swap<uint32_t,D>(src, dst, byte_count); break;
     case 8: do_conjoint_swap<uint64_t,D>(src, dst, byte_count); break;
     default: guarantee(false, err_msg("do_conjoint_swap: Invalid elem_size %zd\n", elem_size));
     }
   }
 };
 void Copy::conjoint_swap(address src, address dst, size_t byte_count, size_t elem_size) {
   CopySwap::conjoint_swap(src, dst, byte_count, elem_size);
 }
 // Fill bytes; larger units are filled atomically if everything is aligned.
 void Copy::fill_to_memory_atomic(void* to, size_t size, jubyte value) {
   address dst = (address) to;
   uintptr_t bits = (uintptr_t) to | (uintptr_t) size;
   if (bits % sizeof(jlong) == 0) {
     jlong fill = (julong)( (jubyte)value ); // zero-extend
     if (fill != 0) {
       fill += fill << 8;
       fill += fill << 16;
       fill += fill << 32;
     }
     //Copy::fill_to_jlongs_atomic((jlong*) dst, size / sizeof(jlong));
     for (uintptr_t off = 0; off < size; off += sizeof(jlong)) {
       *(jlong*)(dst + off) = fill;
     }
   } else if (bits % sizeof(jint) == 0) {
     jint fill = (juint)( (jubyte)value ); // zero-extend
     if (fill != 0) {
       fill += fill << 8;
       fill += fill << 16;
     }
     //Copy::fill_to_jints_atomic((jint*) dst, size / sizeof(jint));
     for (uintptr_t off = 0; off < size; off += sizeof(jint)) {
       *(jint*)(dst + off) = fill;
     }
   } else if (bits % sizeof(jshort) == 0) {
     jshort fill = (jushort)( (jubyte)value ); // zero-extend
     fill += fill << 8;
     //Copy::fill_to_jshorts_atomic((jshort*) dst, size / sizeof(jshort));
     for (uintptr_t off = 0; off < size; off += sizeof(jshort)) {
       *(jshort*)(dst + off) = fill;
     }
   } else {
     // Not aligned, so no need to be atomic.
     Copy::fill_to_bytes(dst, size, value);
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/copy.cpp@dee6a1ce4a0c (annotated)

src/share/vm/utilities/copy.cpp