x86/ldt: Correct LDT access in single stepping logic

Commit 37868fe113ff ("x86/ldt: Make modify_ldt synchronous")
introduced a new struct ldt_struct anchored at mm->context.ldt.

convert_ip_to_linear() was changed to reflect this, but indexing
into the ldt has to be changed as the pointer is no longer void *.

Signed-off-by: Juergen Gross <[email protected]>
Reviewed-by: Andy Lutomirski <[email protected]>
Cc: <[email protected]> # On top of: 37868fe113ff: x86/ldt: Make modify_ldt synchronous
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 6273324186ac5ca7adba69be5ded69f23d8882f7..0ccb53a9fcd9361b83c7acd26e1f64601816a3d1 100644 (file)
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -28,11 +28,11 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re
                struct desc_struct *desc;
                unsigned long base;
 
-               seg &= ~7UL;
+               seg >>= 3;
 
                mutex_lock(&child->mm->context.lock);
                if (unlikely(!child->mm->context.ldt ||
-                            (seg >> 3) >= child->mm->context.ldt->size))
+                            seg >= child->mm->context.ldt->size))
                        addr = -1L; /* bogus selector, access would fault */
                else {
                        desc = &child->mm->context.ldt->entries[seg];