2 * linux/arch/x86_64/kernel/ioport.c
4 * This contains the io-permission bitmap code - written by obz, with changes
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>
20 /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
21 static void set_bitmap(unsigned long *bitmap
, unsigned int base
, unsigned int extent
, int new_value
)
25 for (i
= base
; i
< base
+ extent
; i
++)
28 for (i
= base
; i
< base
+ extent
; i
++)
33 * this changes the io permissions bitmap in the current task.
35 asmlinkage
long sys_ioperm(unsigned long from
, unsigned long num
, int turn_on
)
37 unsigned int i
, max_long
, bytes
, bytes_updated
;
38 struct thread_struct
* t
= ¤t
->thread
;
39 struct tss_struct
* tss
;
40 unsigned long *bitmap
;
42 if ((from
+ num
<= from
) || (from
+ num
> IO_BITMAP_BITS
))
44 if (turn_on
&& !capable(CAP_SYS_RAWIO
))
48 * If it's the first ioperm() call in this thread's lifetime, set the
49 * IO bitmap up. ioperm() is much less timing critical than clone(),
50 * this is why we delay this operation until now:
52 if (!t
->io_bitmap_ptr
) {
53 bitmap
= kmalloc(IO_BITMAP_BYTES
, GFP_KERNEL
);
57 memset(bitmap
, 0xff, IO_BITMAP_BYTES
);
58 t
->io_bitmap_ptr
= bitmap
;
62 * do it in the per-thread copy and in the TSS ...
64 * Disable preemption via get_cpu() - we must not switch away
65 * because the ->io_bitmap_max value must match the bitmap
68 tss
= &per_cpu(init_tss
, get_cpu());
70 set_bitmap(t
->io_bitmap_ptr
, from
, num
, !turn_on
);
73 * Search for a (possibly new) maximum. This is simple and stupid,
74 * to keep it obviously correct:
77 for (i
= 0; i
< IO_BITMAP_LONGS
; i
++)
78 if (t
->io_bitmap_ptr
[i
] != ~0UL)
81 bytes
= (max_long
+ 1) * sizeof(long);
82 bytes_updated
= max(bytes
, t
->io_bitmap_max
);
84 t
->io_bitmap_max
= bytes
;
87 memcpy(tss
->io_bitmap
, t
->io_bitmap_ptr
, bytes_updated
);
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.
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
105 asmlinkage
long sys_iopl(unsigned int level
, struct pt_regs
*regs
)
107 unsigned int old
= (regs
->eflags
>> 12) & 3;
111 /* Trying to gain more privileges? */
113 if (!capable(CAP_SYS_RAWIO
))
116 regs
->eflags
= (regs
->eflags
&~ 0x3000UL
) | (level
<< 12);