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(domain: 0, bus, devfn: dfn);
31 if (!dev)
32 goto error;
33
34 switch (len) {
35 case 1:
36 cfg_ret = pci_user_read_config_byte(dev, where: off, val: &byte);
37 break;
38 case 2:
39 cfg_ret = pci_user_read_config_word(dev, where: off, val: &word);
40 break;
41 case 4:
42 cfg_ret = pci_user_read_config_dword(dev, where: off, val: &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(what: LOCKDOWN_PCI_ACCESS))
97 return -EPERM;
98
99 dev = pci_get_domain_bus_and_slot(domain: 0, bus, devfn: 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, where: off, val: 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, where: off, val: 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, where: off, val: 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

source code of linux/drivers/pci/syscall.c