source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/arch/i386/kernel/ioport-xen.c @ 34

Last change on this file since 34 was 34, checked in by hartmans, 18 years ago

Add xen and xen-common

File size: 3.1 KB
Line 
1/*
2 *      linux/arch/i386/kernel/ioport.c
3 *
4 * This contains the io-permission bitmap code - written by obz, with changes
5 * by Linus.
6 */
7
8#include <linux/sched.h>
9#include <linux/kernel.h>
10#include <linux/capability.h>
11#include <linux/errno.h>
12#include <linux/types.h>
13#include <linux/ioport.h>
14#include <linux/smp.h>
15#include <linux/smp_lock.h>
16#include <linux/stddef.h>
17#include <linux/slab.h>
18#include <linux/thread_info.h>
19#include <xen/interface/physdev.h>
20
21/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
22static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value)
23{
24        unsigned long mask;
25        unsigned long *bitmap_base = bitmap + (base / BITS_PER_LONG);
26        unsigned int low_index = base & (BITS_PER_LONG-1);
27        int length = low_index + extent;
28
29        if (low_index != 0) {
30                mask = (~0UL << low_index);
31                if (length < BITS_PER_LONG)
32                        mask &= ~(~0UL << length);
33                if (new_value)
34                        *bitmap_base++ |= mask;
35                else
36                        *bitmap_base++ &= ~mask;
37                length -= BITS_PER_LONG;
38        }
39
40        mask = (new_value ? ~0UL : 0UL);
41        while (length >= BITS_PER_LONG) {
42                *bitmap_base++ = mask;
43                length -= BITS_PER_LONG;
44        }
45
46        if (length > 0) {
47                mask = ~(~0UL << length);
48                if (new_value)
49                        *bitmap_base++ |= mask;
50                else
51                        *bitmap_base++ &= ~mask;
52        }
53}
54
55
56/*
57 * this changes the io permissions bitmap in the current task.
58 */
59asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
60{
61        struct thread_struct * t = &current->thread;
62        unsigned long *bitmap;
63        struct physdev_set_iobitmap set_iobitmap;
64
65        if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
66                return -EINVAL;
67        if (turn_on && !capable(CAP_SYS_RAWIO))
68                return -EPERM;
69
70        /*
71         * If it's the first ioperm() call in this thread's lifetime, set the
72         * IO bitmap up. ioperm() is much less timing critical than clone(),
73         * this is why we delay this operation until now:
74         */
75        if (!t->io_bitmap_ptr) {
76                bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
77                if (!bitmap)
78                        return -ENOMEM;
79
80                memset(bitmap, 0xff, IO_BITMAP_BYTES);
81                t->io_bitmap_ptr = bitmap;
82                set_thread_flag(TIF_IO_BITMAP);
83
84                set_xen_guest_handle(set_iobitmap.bitmap, (char *)bitmap);
85                set_iobitmap.nr_ports = IO_BITMAP_BITS;
86                HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &set_iobitmap);
87        }
88
89        set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
90
91        return 0;
92}
93
94/*
95 * sys_iopl has to be used when you want to access the IO ports
96 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
97 * you'd need 8kB of bitmaps/process, which is a bit excessive.
98 *
99 * Here we just change the eflags value on the stack: we allow
100 * only the super-user to do it. This depends on the stack-layout
101 * on system-call entry - see also fork() and the signal handling
102 * code.
103 */
104
105asmlinkage long sys_iopl(unsigned long unused)
106{
107        volatile struct pt_regs * regs = (struct pt_regs *) &unused;
108        unsigned int level = regs->ebx;
109        struct thread_struct *t = &current->thread;
110        unsigned int old = (t->iopl >> 12) & 3;
111
112        if (level > 3)
113                return -EINVAL;
114        /* Trying to gain more privileges? */
115        if (level > old) {
116                if (!capable(CAP_SYS_RAWIO))
117                        return -EPERM;
118        }
119        t->iopl = level << 12;
120        set_iopl_mask(t->iopl);
121        return 0;
122}
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