drivers/pci/syscall.c

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