1 files changed, 77 insertions, 0 deletions
diff --git a/lib/i386-io-linux.h b/lib/i386-io-linux.h
new file mode 100644
index 0000000..317f079
--- /dev/null
+++ b/lib/i386-io-linux.h
@@ -0,0 +1,77 @@
+/*
+ *	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)
+{
+}