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/*
* The PCI Library -- Access to i386 I/O ports on Linux
*
* Copyright (c) 1997--2006 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL v2+
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <sys/io.h>
#include <errno.h>
#include "i386-io-access.h"
static int ioperm_enabled;
static int iopl_enabled;
static int
intel_setup_io(struct pci_access *a UNUSED)
{
if (ioperm_enabled || iopl_enabled)
return 1;
/*
* Before Linux 2.6.8, only the first 0x3ff I/O ports permissions can be
* modified via ioperm(). Since 2.6.8 all ports are supported.
* Since Linux 5.5, EFLAGS-based iopl() implementation was removed and
* replaced by new TSS-IOPB-map-all-based emulator. Before Linux 5.5,
* EFLAGS-based iopl() allowed userspace to enable/disable interrupts,
* which is dangerous. So prefer usage of ioperm() and fallback to iopl().
*/
if (ioperm(0xcf8, 8, 1) < 0) /* conf1 + conf2 ports */
{
if (errno == EINVAL) /* ioperm() unsupported */
{
if (iopl(3) < 0)
return 0;
iopl_enabled = 1;
return 1;
}
return 0;
}
if (ioperm(0xc000, 0xfff, 1) < 0) /* remaining conf2 ports */
{
ioperm(0xcf8, 8, 0);
return 0;
}
ioperm_enabled = 1;
return 1;
}
static inline void
intel_cleanup_io(struct pci_access *a UNUSED)
{
if (ioperm_enabled)
{
ioperm(0xcf8, 8, 0);
ioperm(0xc000, 0xfff, 0);
ioperm_enabled = 0;
}
if (iopl_enabled)
{
iopl(0);
iopl_enabled = 0;
}
}
static inline void intel_io_lock(void)
{
}
static inline void intel_io_unlock(void)
{
}
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