1// SPDX-License-Identifier: GPL-2.0
2/*
3 * For architectures where we want to allow direct access to the PCI config
4 * stuff - it would probably be preferable on PCs too, but there people
5 * just do it by hand with the magic northbridge registers.
6 */
7
8#include <linux/errno.h>
9#include <linux/pci.h>
10#include <linux/security.h>
11#include <linux/syscalls.h>
12#include <linux/uaccess.h>
13#include "pci.h"
14
15SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,
16		unsigned long, off, unsigned long, len, void __user *, buf)
17{
18	struct pci_dev *dev;
19	u8 byte;
20	u16 word;
21	u32 dword;
22	int err, cfg_ret;
23
24	err = -EPERM;
25	dev = NULL;
26	if (!capable(CAP_SYS_ADMIN))
27		goto error;
28
29	err = -ENODEV;
30	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
31	if (!dev)
32		goto error;
33
34	switch (len) {
35	case 1:
36		cfg_ret = pci_user_read_config_byte(dev, off, &byte);
37		break;
38	case 2:
39		cfg_ret = pci_user_read_config_word(dev, off, &word);
40		break;
41	case 4:
42		cfg_ret = pci_user_read_config_dword(dev, off, &dword);
43		break;
44	default:
45		err = -EINVAL;
46		goto error;
47	}
48
49	err = -EIO;
50	if (cfg_ret)
51		goto error;
52
53	switch (len) {
54	case 1:
55		err = put_user(byte, (u8 __user *)buf);
56		break;
57	case 2:
58		err = put_user(word, (u16 __user *)buf);
59		break;
60	case 4:
61		err = put_user(dword, (u32 __user *)buf);
62		break;
63	}
64	pci_dev_put(dev);
65	return err;
66
67error:
68	/* ??? XFree86 doesn't even check the return value.  They
69	   just look for 0xffffffff in the output, since that's what
70	   they get instead of a machine check on x86.  */
71	switch (len) {
72	case 1:
73		put_user(-1, (u8 __user *)buf);
74		break;
75	case 2:
76		put_user(-1, (u16 __user *)buf);
77		break;
78	case 4:
79		put_user(-1, (u32 __user *)buf);
80		break;
81	}
82	pci_dev_put(dev);
83	return err;
84}
85
86SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
87		unsigned long, off, unsigned long, len, void __user *, buf)
88{
89	struct pci_dev *dev;
90	u8 byte;
91	u16 word;
92	u32 dword;
93	int err = 0;
94
95	if (!capable(CAP_SYS_ADMIN) ||
96	    security_locked_down(LOCKDOWN_PCI_ACCESS))
97		return -EPERM;
98
99	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
100	if (!dev)
101		return -ENODEV;
102
103	switch (len) {
104	case 1:
105		err = get_user(byte, (u8 __user *)buf);
106		if (err)
107			break;
108		err = pci_user_write_config_byte(dev, off, byte);
109		if (err)
110			err = -EIO;
111		break;
112
113	case 2:
114		err = get_user(word, (u16 __user *)buf);
115		if (err)
116			break;
117		err = pci_user_write_config_word(dev, off, word);
118		if (err)
119			err = -EIO;
120		break;
121
122	case 4:
123		err = get_user(dword, (u32 __user *)buf);
124		if (err)
125			break;
126		err = pci_user_write_config_dword(dev, off, dword);
127		if (err)
128			err = -EIO;
129		break;
130
131	default:
132		err = -EINVAL;
133		break;
134	}
135	pci_dev_put(dev);
136	return err;
137}
138