2 * linux/arch/i386/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>
19 #include <xen/interface/physdev.h>
21 /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
22 static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value)
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;
30 mask = (~0UL << low_index);
31 if (length < BITS_PER_LONG)
32 mask &= ~(~0UL << length);
34 *bitmap_base++ |= mask;
36 *bitmap_base++ &= ~mask;
37 length -= BITS_PER_LONG;
40 mask = (new_value ? ~0UL : 0UL);
41 while (length >= BITS_PER_LONG) {
42 *bitmap_base++ = mask;
43 length -= BITS_PER_LONG;
47 mask = ~(~0UL << length);
49 *bitmap_base++ |= mask;
51 *bitmap_base++ &= ~mask;
57 * this changes the io permissions bitmap in the current task.
59 asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
61 struct thread_struct * t = ¤t->thread;
62 unsigned long *bitmap;
63 struct physdev_set_iobitmap set_iobitmap;
65 if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
67 if (turn_on && !capable(CAP_SYS_RAWIO))
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:
75 if (!t->io_bitmap_ptr) {
76 bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
80 memset(bitmap, 0xff, IO_BITMAP_BYTES);
81 t->io_bitmap_ptr = bitmap;
83 set_iobitmap.bitmap = (char *)bitmap;
84 set_iobitmap.nr_ports = IO_BITMAP_BITS;
85 HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &set_iobitmap);
88 set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
94 * sys_iopl has to be used when you want to access the IO ports
95 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
96 * you'd need 8kB of bitmaps/process, which is a bit excessive.
98 * Here we just change the eflags value on the stack: we allow
99 * only the super-user to do it. This depends on the stack-layout
100 * on system-call entry - see also fork() and the signal handling
104 asmlinkage long sys_iopl(unsigned long unused)
106 volatile struct pt_regs * regs = (struct pt_regs *) &unused;
107 unsigned int level = regs->ebx;
108 struct thread_struct *t = ¤t->thread;
109 unsigned int old = (t->iopl >> 12) & 3;
113 /* Trying to gain more privileges? */
115 if (!capable(CAP_SYS_RAWIO))
118 t->iopl = level << 12;
119 set_iopl_mask(t->iopl);