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>
22 * this changes the io permissions bitmap in the current task.
24 asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
26 struct thread_struct *t = ¤t->thread;
27 struct tss_struct *tss;
28 unsigned int i, max_long, bytes, bytes_updated;
30 if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
32 if (turn_on && !capable(CAP_SYS_RAWIO))
36 * If it's the first ioperm() call in this thread's lifetime, set the
37 * IO bitmap up. ioperm() is much less timing critical than clone(),
38 * this is why we delay this operation until now:
40 if (!t->io_bitmap_ptr) {
41 unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
46 memset(bitmap, 0xff, IO_BITMAP_BYTES);
47 t->io_bitmap_ptr = bitmap;
48 set_thread_flag(TIF_IO_BITMAP);
56 * do it in the per-thread copy and in the TSS ...
58 * Disable preemption via get_cpu() - we must not switch away
59 * because the ->io_bitmap_max value must match the bitmap
62 tss = &per_cpu(cpu_tss, get_cpu());
65 bitmap_clear(t->io_bitmap_ptr, from, num);
67 bitmap_set(t->io_bitmap_ptr, from, num);
70 * Search for a (possibly new) maximum. This is simple and stupid,
71 * to keep it obviously correct:
74 for (i = 0; i < IO_BITMAP_LONGS; i++)
75 if (t->io_bitmap_ptr[i] != ~0UL)
78 bytes = (max_long + 1) * sizeof(unsigned long);
79 bytes_updated = max(bytes, t->io_bitmap_max);
81 t->io_bitmap_max = bytes;
84 memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
92 * sys_iopl has to be used when you want to access the IO ports
93 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
94 * you'd need 8kB of bitmaps/process, which is a bit excessive.
96 * Here we just change the flags value on the stack: we allow
97 * only the super-user to do it. This depends on the stack-layout
98 * on system-call entry - see also fork() and the signal handling
101 SYSCALL_DEFINE1(iopl, unsigned int, level)
103 struct pt_regs *regs = current_pt_regs();
104 struct thread_struct *t = ¤t->thread;
107 * Careful: the IOPL bits in regs->flags are undefined under Xen PV
108 * and changing them has no effect.
110 unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT;
114 /* Trying to gain more privileges? */
116 if (!capable(CAP_SYS_RAWIO))
119 regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
120 (level << X86_EFLAGS_IOPL_BIT);
121 t->iopl = level << X86_EFLAGS_IOPL_BIT;
122 set_iopl_mask(t->iopl);