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 <linux/bitmap.h>
18 #include <asm/syscalls.h>
21 * this changes the io permissions bitmap in the current task.
23 asmlinkage
long sys_ioperm(unsigned long from
, unsigned long num
, int turn_on
)
25 struct thread_struct
*t
= ¤t
->thread
;
26 struct tss_struct
*tss
;
27 unsigned int i
, max_long
, bytes
, bytes_updated
;
29 if ((from
+ num
<= from
) || (from
+ num
> IO_BITMAP_BITS
))
31 if (turn_on
&& !capable(CAP_SYS_RAWIO
))
35 * If it's the first ioperm() call in this thread's lifetime, set the
36 * IO bitmap up. ioperm() is much less timing critical than clone(),
37 * this is why we delay this operation until now:
39 if (!t
->io_bitmap_ptr
) {
40 unsigned long *bitmap
= kmalloc(IO_BITMAP_BYTES
, GFP_KERNEL
);
45 memset(bitmap
, 0xff, IO_BITMAP_BYTES
);
46 t
->io_bitmap_ptr
= bitmap
;
47 set_thread_flag(TIF_IO_BITMAP
);
51 * do it in the per-thread copy and in the TSS ...
53 * Disable preemption via get_cpu() - we must not switch away
54 * because the ->io_bitmap_max value must match the bitmap
57 tss
= &per_cpu(cpu_tss
, get_cpu());
60 bitmap_clear(t
->io_bitmap_ptr
, from
, num
);
62 bitmap_set(t
->io_bitmap_ptr
, from
, num
);
65 * Search for a (possibly new) maximum. This is simple and stupid,
66 * to keep it obviously correct:
69 for (i
= 0; i
< IO_BITMAP_LONGS
; i
++)
70 if (t
->io_bitmap_ptr
[i
] != ~0UL)
73 bytes
= (max_long
+ 1) * sizeof(unsigned long);
74 bytes_updated
= max(bytes
, t
->io_bitmap_max
);
76 t
->io_bitmap_max
= bytes
;
79 memcpy(tss
->io_bitmap
, t
->io_bitmap_ptr
, bytes_updated
);
87 * sys_iopl has to be used when you want to access the IO ports
88 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
89 * you'd need 8kB of bitmaps/process, which is a bit excessive.
91 * Here we just change the flags value on the stack: we allow
92 * only the super-user to do it. This depends on the stack-layout
93 * on system-call entry - see also fork() and the signal handling
96 SYSCALL_DEFINE1(iopl
, unsigned int, level
)
98 struct pt_regs
*regs
= current_pt_regs();
99 struct thread_struct
*t
= ¤t
->thread
;
102 * Careful: the IOPL bits in regs->flags are undefined under Xen PV
103 * and changing them has no effect.
105 unsigned int old
= t
->iopl
>> X86_EFLAGS_IOPL_BIT
;
109 /* Trying to gain more privileges? */
111 if (!capable(CAP_SYS_RAWIO
))
114 regs
->flags
= (regs
->flags
& ~X86_EFLAGS_IOPL
) |
115 (level
<< X86_EFLAGS_IOPL_BIT
);
116 t
->iopl
= level
<< X86_EFLAGS_IOPL_BIT
;
117 set_iopl_mask(t
->iopl
);