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1275 |
phoenix |
/*
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* linux/arch/x86_64/kernel/ioport.c
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*
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* This contains the io-permission bitmap code - written by obz, with changes
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* by Linus.
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*/
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/ioport.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/stddef.h>
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/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
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static void set_bitmap(unsigned long *bitmap, short base, short extent, int new_value)
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{
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int i;
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if (new_value)
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for (i = base; i < base + extent; i++)
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__set_bit(i, bitmap);
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else
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for (i = base; i < base + extent; i++)
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clear_bit(i, bitmap);
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}
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/*
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* this changes the io permissions bitmap in the current task.
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*/
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asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
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{
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struct thread_struct * t = ¤t->thread;
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struct tss_struct * tss = init_tss + smp_processor_id();
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if ((from + num <= from) || (from + num > IO_BITMAP_SIZE*32))
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return -EINVAL;
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if (turn_on && !capable(CAP_SYS_RAWIO))
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return -EPERM;
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/*
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* If it's the first ioperm() call in this thread's lifetime, set the
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* IO bitmap up. ioperm() is much less timing critical than clone(),
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* this is why we delay this operation until now:
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*/
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if (!t->io_bitmap_ptr) {
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t->io_bitmap_ptr = kmalloc((IO_BITMAP_SIZE+1)*4, GFP_KERNEL);
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if (!t->io_bitmap_ptr)
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return -ENOMEM;
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memset(t->io_bitmap_ptr,0xff,(IO_BITMAP_SIZE+1)*4);
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/*
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* this activates it in the TSS
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*/
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}
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/*
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* do it in the per-thread copy and in the TSS ...
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*/
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set_bitmap((unsigned long *) t->io_bitmap_ptr, from, num, !turn_on);
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if (tss->io_map_base != IO_BITMAP_OFFSET) {
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memcpy(tss->io_bitmap, t->io_bitmap_ptr, sizeof(tss->io_bitmap));
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tss->io_map_base = IO_BITMAP_OFFSET;
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} else {
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set_bitmap((unsigned long *) tss->io_bitmap, from, num, !turn_on);
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}
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return 0;
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}
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/*
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* sys_iopl has to be used when you want to access the IO ports
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* beyond the 0x3ff range: to get the full 65536 ports bitmapped
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* you'd need 8kB of bitmaps/process, which is a bit excessive.
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*
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* Here we just change the eflags value on the stack: we allow
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* only the super-user to do it. This depends on the stack-layout
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* on system-call entry - see also fork() and the signal handling
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* code.
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*/
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asmlinkage long sys_iopl(unsigned int level, struct pt_regs regs)
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{
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unsigned int old = (regs.eflags >> 12) & 3;
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if (level > 3)
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return -EINVAL;
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/* Trying to gain more privileges? */
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if (level > old) {
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if (!capable(CAP_SYS_RAWIO))
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return -EPERM;
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}
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regs.eflags = (regs.eflags & 0xffffffffffffcfff) | (level << 12);
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return 0;
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}
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