1 files changed, 137 insertions, 0 deletions
diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
new file mode 100644
index 0000000000..803acbf33e
--- /dev/null
+++ b/drivers/pci/syscall.c
@@ -0,0 +1,137 @@
+// 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/security.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;
+	int err, cfg_ret;
+
+	err = -EPERM;
+	dev = NULL;
+	if (!capable(CAP_SYS_ADMIN))
+		goto error;
+
+	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)
+		goto error;
+
+	switch (len) {
+	case 1:
+		err = put_user(byte, (u8 __user *)buf);
+		break;
+	case 2:
+		err = put_user(word, (u16 __user *)buf);
+		break;
+	case 4:
+		err = put_user(dword, (u32 __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, (u8 __user *)buf);
+		break;
+	case 2:
+		put_user(-1, (u16 __user *)buf);
+		break;
+	case 4:
+		put_user(-1, (u32 __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) ||
+	    security_locked_down(LOCKDOWN_PCI_ACCESS))
+		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)
+			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)
+			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)
+			err = -EIO;
+		break;
+
+	default:
+		err = -EINVAL;
+		break;
+	}
+	pci_dev_put(dev);
+	return err;
+}