x86: unify desc_struct

This patch aims to make the access of struct desc_struct variables
equal across architectures. In this patch, I unify the i386 and x86_64
versions under an anonymous union, keeping the way they are accessed
untouched (a and b for 32-bit code, individual bit-fields for 64-bit).

This solution is not beautiful, but will allow us to integrate common
code that differed by the way descriptors were used. This is to be viewed
incrementally. There's simply too much code to be fixed at once.

In the future, goal is to set up in a single way of acessing
the desc_struct fields.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 17 insertions, 8 deletions

diff --git a/include/asm-x86/desc_defs.h b/include/asm-x86/desc_defs.h
index 089004070099..de47eb0a23aa 100644
--- a/include/asm-x86/desc_defs.h
+++ b/include/asm-x86/desc_defs.h
@@ -11,17 +11,26 @@
 
 #include <linux/types.h>
 
+/*
+ * FIXME: Acessing the desc_struct through its fields is more elegant,
+ * and should be the one valid thing to do. However, a lot of open code
+ * still touches the a and b acessors, and doing this allow us to do it
+ * incrementally. We keep the signature as a struct, rather than an union,
+ * so we can get rid of it transparently in the future -- glommer
+ */
 // 8 byte segment descriptor
 struct desc_struct {
-        u16 limit0;
-        u16 base0;
-        unsigned base1 : 8, type : 4, s : 1, dpl : 2, p : 1;
-        unsigned limit : 4, avl : 1, l : 1, d : 1, g : 1, base2 : 8;
-} __attribute__((packed));
+        union {
+                struct { unsigned int a, b; };
+                struct {
+                        u16 limit0;
+                        u16 base0;
+                        unsigned base1: 8, type: 4, s: 1, dpl: 2, p: 1;
+                        unsigned limit: 4, avl: 1, l: 1, d: 1, g: 1, base2: 8;
+                };
 
-struct n_desc_struct {
-        unsigned int a,b;
-};
+        };
+} __attribute__((packed));
 
 enum {
         GATE_INTERRUPT = 0xE,