LXR qemu/page-vary-target.c

   1/*
   2 * Variable page size handling -- target specific part.
   3 *
   4 *  Copyright (c) 2003 Fabrice Bellard
   5 *
   6 * This library is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU Lesser General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2.1 of the License, or (at your option) any later version.
  10 *
  11 * This library is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * Lesser General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU Lesser General Public
  17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20#define IN_PAGE_VARY 1
  21
  22#include "qemu/osdep.h"
  23#include "exec/page-vary.h"
  24#include "exec/target_page.h"
  25
  26
  27/*
  28 * For system mode, the minimum comes from the number of bits
  29 * required for maximum alignment (6) and the number of bits
  30 * required for TLB_FLAGS_MASK (3).
  31 *
  32 * For user mode, TARGET_PAGE_BITS_VARY is a hack to allow the target
  33 * page size to match the host page size.  Mostly, this reduces the
  34 * ordinary target page size to run on a host with 4KiB pages (i.e. x86).
  35 * There is no true minimum required by the implementation, but keep the
  36 * same minimum as for system mode for sanity.
  37 * See linux-user/mmap.c, mmap_h_lt_g and mmap_h_gt_g.
  38 */
  39#define TARGET_PAGE_BITS_MIN 9
  40
  41#ifndef TARGET_PAGE_BITS_VARY
  42QEMU_BUILD_BUG_ON(TARGET_PAGE_BITS < TARGET_PAGE_BITS_MIN);
  43#endif
  44
  45#ifndef CONFIG_USER_ONLY
  46#include "exec/tlb-flags.h"
  47
  48QEMU_BUILD_BUG_ON(TLB_FLAGS_MASK & ((1u < TARGET_PAGE_BITS_MIN) - 1));
  49
  50int migration_legacy_page_bits(void)
  51{
  52#ifdef TARGET_PAGE_BITS_VARY
  53    QEMU_BUILD_BUG_ON(TARGET_PAGE_BITS_LEGACY < TARGET_PAGE_BITS_MIN);
  54    return TARGET_PAGE_BITS_LEGACY;
  55#else
  56    return TARGET_PAGE_BITS;
  57#endif
  58}
  59#endif
  60
  61bool set_preferred_target_page_bits(int bits)
  62{
  63    assert(bits >= TARGET_PAGE_BITS_MIN);
  64#ifdef TARGET_PAGE_BITS_VARY
  65    return set_preferred_target_page_bits_common(bits);
  66#else
  67    return true;
  68#endif
  69}
  70
  71void finalize_target_page_bits(void)
  72{
  73#ifndef TARGET_PAGE_BITS_VARY
  74    finalize_target_page_bits_common(TARGET_PAGE_BITS);
  75#elif defined(CONFIG_USER_ONLY)
  76    assert(target_page.bits != 0);
  77    finalize_target_page_bits_common(target_page.bits);
  78#else
  79    finalize_target_page_bits_common(TARGET_PAGE_BITS_LEGACY);
  80#endif
  81}
  82