Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * This contains the io-permission bitmap code - written by obz, with changes

 * by Linus.

 */

#include <linux/sched.h>

#include <linux/kernel.h>

#include <linux/capability.h>

#include <linux/errno.h>

#include <linux/types.h>

#include <linux/ioport.h>

#include <linux/smp.h>

#include <linux/stddef.h>

#include <linux/slab.h>

#include <linux/thread_info.h>

#include <linux/syscalls.h>

/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */

static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value)

{

        int i;

                if (new_value)

                for (i = base; i < base + extent; i++)

                        __set_bit(i, bitmap);

                else

                for (i = base; i < base + extent; i++)

                        clear_bit(i, bitmap);

}

/*

 * this changes the io permissions bitmap in the current task.

 */

asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)

{

        unsigned int i, max_long, bytes, bytes_updated;

        struct thread_struct * t = &current->thread;

        struct tss_struct * tss;

        unsigned long *bitmap;

        if ((from + num <= from) || (from + num > IO_BITMAP_BITS))

                return -EINVAL;

        if (turn_on && !capable(CAP_SYS_RAWIO))

                return -EPERM;

        /*

         * If it's the first ioperm() call in this thread's lifetime, set the

         * IO bitmap up. ioperm() is much less timing critical than clone(),

         * this is why we delay this operation until now:

         */

        if (!t->io_bitmap_ptr) {

                bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);

                if (!bitmap)

                        return -ENOMEM;

                memset(bitmap, 0xff, IO_BITMAP_BYTES);

                t->io_bitmap_ptr = bitmap;

                set_thread_flag(TIF_IO_BITMAP);

        }

        /*

         * do it in the per-thread copy and in the TSS ...

         *

         * Disable preemption via get_cpu() - we must not switch away

         * because the ->io_bitmap_max value must match the bitmap

         * contents:

         */

        tss = &per_cpu(init_tss, get_cpu());

        set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);

        /*

         * Search for a (possibly new) maximum. This is simple and stupid,

         * to keep it obviously correct:

         */

        max_long = 0;

        for (i = 0; i < IO_BITMAP_LONGS; i++)

                if (t->io_bitmap_ptr[i] != ~0UL)

                        max_long = i;

        bytes = (max_long + 1) * sizeof(long);

        bytes_updated = max(bytes, t->io_bitmap_max);

        t->io_bitmap_max = bytes;

        /* Update the TSS: */

        memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);

        put_cpu();

        return 0;

}

/*

 * sys_iopl has to be used when you want to access the IO ports

 * beyond the 0x3ff range: to get the full 65536 ports bitmapped

 * you'd need 8kB of bitmaps/process, which is a bit excessive.

 *

 * Here we just change the eflags value on the stack: we allow

 * only the super-user to do it. This depends on the stack-layout

 * on system-call entry - see also fork() and the signal handling

 * code.

 */

asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)

{

        unsigned int old = (regs->eflags >> 12) & 3;

        if (level > 3)

                return -EINVAL;

        /* Trying to gain more privileges? */

        if (level > old) {

                if (!capable(CAP_SYS_RAWIO))

                        return -EPERM;

        }

        regs->eflags = (regs->eflags &~ X86_EFLAGS_IOPL) | (level << 12);

        return 0;

}