patch-2.4.20 linux-2.4.20/arch/x86_64/kernel/ioport.c

• Lines: 116
• Date: Thu Nov 28 15:53:12 2002
• Orig file: linux-2.4.19/arch/x86_64/kernel/ioport.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/x86_64/kernel/ioport.c linux-2.4.20/arch/x86_64/kernel/ioport.c
@@ -0,0 +1,115 @@
+/*
+ *	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/errno.h>
+#include <linux/types.h>
+#include <linux/ioport.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/stddef.h>
+
+/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
+static void set_bitmap(unsigned long *bitmap, short base, short extent, int new_value)
+{
+	int mask;
+	unsigned long *bitmap_base = bitmap + (base >> 6);
+	unsigned short low_index = base & 0x3f;
+	int length = low_index + extent;
+
+	if (low_index != 0) {
+		mask = (~0 << low_index);
+		if (length < 64)
+				mask &= ~(~0 << length);
+		if (new_value)
+			*bitmap_base++ |= mask;
+		else
+			*bitmap_base++ &= ~mask;
+		length -= 32;
+	}
+
+	mask = (new_value ? ~0 : 0);
+	while (length >= 64) {
+		*bitmap_base++ = mask;
+		length -= 64;
+	}
+
+	if (length > 0) {
+		mask = ~(~0 << length);
+		if (new_value)
+			*bitmap_base++ |= mask;
+		else
+			*bitmap_base++ &= ~mask;
+	}
+}
+
+/*
+ * this changes the io permissions bitmap in the current task.
+ */
+asmlinkage int sys_ioperm(unsigned long from, unsigned long num, int turn_on)
+{
+	struct thread_struct * t = &current->thread;
+	struct tss_struct * tss = init_tss + smp_processor_id();
+
+	if ((from + num <= from) || (from + num > IO_BITMAP_SIZE*32))
+		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) {
+		t->io_bitmap_ptr = kmalloc((IO_BITMAP_SIZE+1)*4, GFP_KERNEL);
+		if (!t->io_bitmap_ptr) 
+			return -ENOMEM; 
+
+		memset(t->io_bitmap_ptr,0xff,(IO_BITMAP_SIZE+1)*4);
+		/*
+		 * this activates it in the TSS
+		 */
+		tss->io_map_base = IO_BITMAP_OFFSET;
+	}
+
+	/*
+	 * do it in the per-thread copy and in the TSS ...
+	 */
+	set_bitmap((unsigned long *) t->io_bitmap_ptr, from, num, !turn_on);
+	set_bitmap((unsigned long *) tss->io_bitmap, from, num, !turn_on);
+
+	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 & 0xffffffffffffcfff) | (level << 12);
+	return 0;
+}