unicorn/qemu/exec-vary.c

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2021-10-03 17:14:44 +03:00
/*
* Variable page size handling
*
* Copyright (c) 2003 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu-common.h"
#define IN_EXEC_VARY 1
#include "exec/exec-all.h"
#include <uc_priv.h>
bool set_preferred_target_page_bits(struct uc_struct *uc, int bits)
{
/*
* The target page size is the lowest common denominator for all
* the CPUs in the system, so we can only make it smaller, never
* larger. And we can't make it smaller once we've committed to
* a particular size.
*/
#ifdef TARGET_PAGE_BITS_VARY
assert(bits >= TARGET_PAGE_BITS_MIN);
if (uc->init_target_page->bits == 0 || uc->init_target_page->bits > bits) {
if (uc->init_target_page->decided) {
return false;
}
uc->init_target_page->bits = bits;
}
#endif
return true;
}
void finalize_target_page_bits(struct uc_struct *uc)
{
#ifdef TARGET_PAGE_BITS_VARY
if (uc->init_target_page == NULL) {
uc->init_target_page = g_new0(TargetPageBits, 1);
} else {
return;
}
if (uc->init_target_page->bits == 0) {
uc->init_target_page->bits = TARGET_PAGE_BITS_MIN;
}
uc->init_target_page->mask = (target_long)-1 << uc->init_target_page->bits;
uc->init_target_page->decided = true;
/*
* For the benefit of an -flto build, prevent the compiler from
* hoisting a read from target_page before we finish initializing.
*/
barrier();
#endif
}