v4.19.13 snapshot.
diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
new file mode 100644
index 0000000..d96626c
--- /dev/null
+++ b/drivers/pci/syscall.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * For architectures where we want to allow direct access to the PCI config
+ * stuff - it would probably be preferable on PCs too, but there people
+ * just do it by hand with the magic northbridge registers.
+ */
+
+#include <linux/errno.h>
+#include <linux/pci.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+#include "pci.h"
+
+SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,
+ unsigned long, off, unsigned long, len, void __user *, buf)
+{
+ struct pci_dev *dev;
+ u8 byte;
+ u16 word;
+ u32 dword;
+ long err;
+ long cfg_ret;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ err = -ENODEV;
+ dev = pci_get_domain_bus_and_slot(0, bus, dfn);
+ if (!dev)
+ goto error;
+
+ switch (len) {
+ case 1:
+ cfg_ret = pci_user_read_config_byte(dev, off, &byte);
+ break;
+ case 2:
+ cfg_ret = pci_user_read_config_word(dev, off, &word);
+ break;
+ case 4:
+ cfg_ret = pci_user_read_config_dword(dev, off, &dword);
+ break;
+ default:
+ err = -EINVAL;
+ goto error;
+ }
+
+ err = -EIO;
+ if (cfg_ret != PCIBIOS_SUCCESSFUL)
+ goto error;
+
+ switch (len) {
+ case 1:
+ err = put_user(byte, (unsigned char __user *)buf);
+ break;
+ case 2:
+ err = put_user(word, (unsigned short __user *)buf);
+ break;
+ case 4:
+ err = put_user(dword, (unsigned int __user *)buf);
+ break;
+ }
+ pci_dev_put(dev);
+ return err;
+
+error:
+ /* ??? XFree86 doesn't even check the return value. They
+ just look for 0xffffffff in the output, since that's what
+ they get instead of a machine check on x86. */
+ switch (len) {
+ case 1:
+ put_user(-1, (unsigned char __user *)buf);
+ break;
+ case 2:
+ put_user(-1, (unsigned short __user *)buf);
+ break;
+ case 4:
+ put_user(-1, (unsigned int __user *)buf);
+ break;
+ }
+ pci_dev_put(dev);
+ return err;
+}
+
+SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
+ unsigned long, off, unsigned long, len, void __user *, buf)
+{
+ struct pci_dev *dev;
+ u8 byte;
+ u16 word;
+ u32 dword;
+ int err = 0;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ dev = pci_get_domain_bus_and_slot(0, bus, dfn);
+ if (!dev)
+ return -ENODEV;
+
+ switch (len) {
+ case 1:
+ err = get_user(byte, (u8 __user *)buf);
+ if (err)
+ break;
+ err = pci_user_write_config_byte(dev, off, byte);
+ if (err != PCIBIOS_SUCCESSFUL)
+ err = -EIO;
+ break;
+
+ case 2:
+ err = get_user(word, (u16 __user *)buf);
+ if (err)
+ break;
+ err = pci_user_write_config_word(dev, off, word);
+ if (err != PCIBIOS_SUCCESSFUL)
+ err = -EIO;
+ break;
+
+ case 4:
+ err = get_user(dword, (u32 __user *)buf);
+ if (err)
+ break;
+ err = pci_user_write_config_dword(dev, off, dword);
+ if (err != PCIBIOS_SUCCESSFUL)
+ err = -EIO;
+ break;
+
+ default:
+ err = -EINVAL;
+ break;
+ }
+ pci_dev_put(dev);
+ return err;
+}