1 files changed, 153 insertions, 0 deletions

diff --git a/arch/x86/kernel/ioport_32.c b/arch/x86/kernel/ioport_32.c
new file mode 100644
index 000000000000..3d310a946d76
--- /dev/null
+++ b/arch/x86/kernel/ioport_32.c
@@ -0,0 +1,153 @@
+/*
+ *      linux/arch/i386/kernel/ioport.c
+ *
+ * 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)
+{
+        unsigned long mask;
+        unsigned long *bitmap_base = bitmap + (base / BITS_PER_LONG);
+        unsigned int low_index = base & (BITS_PER_LONG-1);
+        int length = low_index + extent;
+
+        if (low_index != 0) {
+                mask = (~0UL << low_index);
+                if (length < BITS_PER_LONG)
+                        mask &= ~(~0UL << length);
+                if (new_value)
+                        *bitmap_base++ |= mask;
+                else
+                        *bitmap_base++ &= ~mask;
+                length -= BITS_PER_LONG;
+        }
+
+        mask = (new_value ? ~0UL : 0UL);
+        while (length >= BITS_PER_LONG) {
+                *bitmap_base++ = mask;
+                length -= BITS_PER_LONG;
+        }
+
+        if (length > 0) {
+                mask = ~(~0UL << length);
+                if (new_value)
+                        *bitmap_base++ |= mask;
+                else
+                        *bitmap_base++ &= ~mask;
+        }
+}
+
+
+/*
+ * this changes the io permissions bitmap in the current task.
+ */
+asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
+{
+        unsigned long 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;
+
+        /*
+         * Sets the lazy trigger so that the next I/O operation will
+         * reload the correct bitmap.
+         * Reset the owner so that a process switch will not set
+         * tss->io_bitmap_base to IO_BITMAP_OFFSET.
+         */
+        tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+        tss->io_bitmap_owner = NULL;
+
+        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 long unused)
+{
+        volatile struct pt_regs * regs = (struct pt_regs *) &unused;
+        unsigned int level = regs->ebx;
+        unsigned int old = (regs->eflags >> 12) & 3;
+        struct thread_struct *t = &current->thread;
+
+        if (level > 3)
+                return -EINVAL;
+        /* Trying to gain more privileges? */
+        if (level > old) {
+                if (!capable(CAP_SYS_RAWIO))
+                        return -EPERM;
+        }
+        t->iopl = level << 12;
+        regs->eflags = (regs->eflags & ~X86_EFLAGS_IOPL) | t->iopl;
+        set_iopl_mask(t->iopl);
+        return 0;
+}