2 * This contains the io-permission bitmap code - written by obz, with changes
3 * by Linus. 32/64 bits code unification by Miguel Botón.
6 #include <linux/sched.h>
7 #include <linux/kernel.h>
8 #include <linux/capability.h>
9 #include <linux/errno.h>
10 #include <linux/types.h>
11 #include <linux/ioport.h>
12 #include <linux/smp.h>
13 #include <linux/stddef.h>
14 #include <linux/slab.h>
15 #include <linux/thread_info.h>
16 #include <linux/syscalls.h>
17 #include <asm/syscalls.h>
19 /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
20 static void set_bitmap(unsigned long *bitmap
, unsigned int base
,
21 unsigned int extent
, int new_value
)
25 for (i
= base
; i
< base
+ extent
; i
++) {
29 __clear_bit(i
, bitmap
);
34 * this changes the io permissions bitmap in the current task.
36 asmlinkage
long sys_ioperm(unsigned long from
, unsigned long num
, int turn_on
)
38 struct thread_struct
*t
= ¤t
->thread
;
39 struct tss_struct
*tss
;
40 unsigned int i
, max_long
, bytes
, bytes_updated
;
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 unsigned long *bitmap
= kmalloc(IO_BITMAP_BYTES
, GFP_KERNEL
);
58 memset(bitmap
, 0xff, IO_BITMAP_BYTES
);
59 t
->io_bitmap_ptr
= bitmap
;
60 set_thread_flag(TIF_IO_BITMAP
);
64 * do it in the per-thread copy and in the TSS ...
66 * Disable preemption via get_cpu() - we must not switch away
67 * because the ->io_bitmap_max value must match the bitmap
70 tss
= &per_cpu(init_tss
, get_cpu());
72 set_bitmap(t
->io_bitmap_ptr
, from
, num
, !turn_on
);
75 * Search for a (possibly new) maximum. This is simple and stupid,
76 * to keep it obviously correct:
79 for (i
= 0; i
< IO_BITMAP_LONGS
; i
++)
80 if (t
->io_bitmap_ptr
[i
] != ~0UL)
83 bytes
= (max_long
+ 1) * sizeof(unsigned long);
84 bytes_updated
= max(bytes
, t
->io_bitmap_max
);
86 t
->io_bitmap_max
= bytes
;
90 * Sets the lazy trigger so that the next I/O operation will
91 * reload the correct bitmap.
92 * Reset the owner so that a process switch will not set
93 * tss->io_bitmap_base to IO_BITMAP_OFFSET.
95 tss
->x86_tss
.io_bitmap_base
= INVALID_IO_BITMAP_OFFSET_LAZY
;
96 tss
->io_bitmap_owner
= NULL
;
99 memcpy(tss
->io_bitmap
, t
->io_bitmap_ptr
, bytes_updated
);
108 * sys_iopl has to be used when you want to access the IO ports
109 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
110 * you'd need 8kB of bitmaps/process, which is a bit excessive.
112 * Here we just change the flags value on the stack: we allow
113 * only the super-user to do it. This depends on the stack-layout
114 * on system-call entry - see also fork() and the signal handling
117 static int do_iopl(unsigned int level
, struct pt_regs
*regs
)
119 unsigned int old
= (regs
->flags
>> 12) & 3;
123 /* Trying to gain more privileges? */
125 if (!capable(CAP_SYS_RAWIO
))
128 regs
->flags
= (regs
->flags
& ~X86_EFLAGS_IOPL
) | (level
<< 12);
134 asmlinkage
long sys_iopl(unsigned long regsp
)
136 struct pt_regs
*regs
= (struct pt_regs
*)®sp
;
137 unsigned int level
= regs
->bx
;
138 struct thread_struct
*t
= ¤t
->thread
;
141 rc
= do_iopl(level
, regs
);
145 t
->iopl
= level
<< 12;
146 set_iopl_mask(t
->iopl
);
151 asmlinkage
long sys_iopl(unsigned int level
, struct pt_regs
*regs
)
153 return do_iopl(level
, regs
);