1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "memory/resourceArea.hpp"
  27 #include "runtime/icache.hpp"
  28 
  29 // The flush stub function address
  30 AbstractICache::flush_icache_stub_t AbstractICache::_flush_icache_stub = NULL;
  31 
  32 void AbstractICache::initialize() {
  33   // Making this stub must be FIRST use of assembler
  34   ResourceMark rm;
  35 
  36   BufferBlob* b = BufferBlob::create("flush_icache_stub", ICache::stub_size);
  37   if (b == NULL) {
  38     vm_exit_out_of_memory(ICache::stub_size, OOM_MALLOC_ERROR, "CodeCache: no space for flush_icache_stub");
  39   }
  40   CodeBuffer c(b);
  41 
  42   ICacheStubGenerator g(&c);
  43   g.generate_icache_flush(&_flush_icache_stub);
  44 
  45   // The first use of flush_icache_stub must apply it to itself.
  46   // The StubCodeMark destructor in generate_icache_flush will
  47   // call Assembler::flush, which in turn will call invalidate_range,
  48   // which will in turn call the flush stub.  Thus we don't need an
  49   // explicit call to invalidate_range here.  This assumption is
  50   // checked in invalidate_range.
  51 }
  52 
  53 void AbstractICache::call_flush_stub(address start, int lines) {
  54   // The business with the magic number is just a little security.
  55   // We cannot call the flush stub when generating the flush stub
  56   // because it isn't there yet.  So, the stub also returns its third
  57   // parameter.  This is a cheap check that the stub was really executed.
  58   static int magic = 0xbaadbabe;
  59 
  60   int auto_magic = magic; // Make a local copy to avoid race condition
  61   int r = (*_flush_icache_stub)(start, lines, auto_magic);
  62   guarantee(r == auto_magic, "flush stub routine did not execute");
  63   ++magic;
  64 }
  65 
  66 void AbstractICache::invalidate_word(address addr) {
  67   // Because this is called for instruction patching on the fly, long after
  68   // bootstrapping, we execute the stub directly.  Account for a 4-byte word
  69   // spanning two cache lines by computing a start line address by rounding
  70   // addr down to a line_size boundary, and an end line address by adding
  71   // the word size - 1 and rounding the result down to a line_size boundary.
  72   // If we just added word size, we'd mistakenly flush the next cache line
  73   // if the word to be flushed started in the last 4 bytes of the line.
  74   // Doing that would segv if the next line weren't mapped.
  75 
  76   const int word_size_in_bytes = 4; // Always, regardless of platform
  77 
  78   intptr_t start_line = ((intptr_t)addr + 0) & ~(ICache::line_size - 1);
  79   intptr_t end_line   = ((intptr_t)addr + word_size_in_bytes - 1)
  80                                              & ~(ICache::line_size - 1);
  81   (*_flush_icache_stub)((address)start_line, start_line == end_line ? 1 : 2, 0);
  82 }
  83 
  84 void AbstractICache::invalidate_range(address start, int nbytes) {
  85   static bool firstTime = true;
  86   if (firstTime) {
  87     guarantee(start == CAST_FROM_FN_PTR(address, _flush_icache_stub),
  88               "first flush should be for flush stub");
  89     firstTime = false;
  90     return;
  91   }
  92   if (nbytes == 0) {
  93     return;
  94   }
  95   // Align start address to an icache line boundary and transform
  96   // nbytes to an icache line count.
  97   const uint line_offset = mask_address_bits(start, ICache::line_size-1);
  98   if (line_offset != 0) {
  99     start -= line_offset;
 100     nbytes += line_offset;
 101   }
 102   call_flush_stub(start, align_up(nbytes, (int)ICache::line_size) >>
 103                          ICache::log2_line_size);
 104 }
 105 
 106 // For init.cpp
 107 void icache_init() {
 108   ICache::initialize();
 109 }