[PATCH] x86-64: cleanup segments

Move __KERNEL32_CS up into the unused gdt entry.  __KERNEL32_CS is
used when entering the kernel so putting it first is useful when
trying to keep boot gdt sizes to a minimum.

Set the accessed bit on all gdt entries.  We don't care
so there is no need for the cpu to burn the extra cycles,
and it potentially allows the pages to be immutable.  Plus
it is confusing when debugging and your gdt entries mysteriously
change.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>

diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 23b45e79a27c0d613efc34f15a2303b623f39d0a..2b2e2c51e53266eee49eeab3f5006cd33b2a1cdb 100644 (file)
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -362,13 +362,13 @@ gdt:
        
 ENTRY(cpu_gdt_table)
        .quad   0x0000000000000000      /* NULL descriptor */
+       .quad   0x00cf9b000000ffff      /* __KERNEL32_CS */
+       .quad   0x00af9b000000ffff      /* __KERNEL_CS */
+       .quad   0x00cf93000000ffff      /* __KERNEL_DS */
+       .quad   0x00cffb000000ffff      /* __USER32_CS */
+       .quad   0x00cff3000000ffff      /* __USER_DS, __USER32_DS  */
+       .quad   0x00affb000000ffff      /* __USER_CS */
        .quad   0x0                     /* unused */
-       .quad   0x00af9a000000ffff      /* __KERNEL_CS */
-       .quad   0x00cf92000000ffff      /* __KERNEL_DS */
-       .quad   0x00cffa000000ffff      /* __USER32_CS */
-       .quad   0x00cff2000000ffff      /* __USER_DS, __USER32_DS  */           
-       .quad   0x00affa000000ffff      /* __USER_CS */
-       .quad   0x00cf9a000000ffff      /* __KERNEL32_CS */
        .quad   0,0                     /* TSS */
        .quad   0,0                     /* LDT */
        .quad   0,0,0                   /* three TLS descriptors */ 

diff --git a/include/asm-x86_64/segment.h b/include/asm-x86_64/segment.h
index 334ddcdd8f92dd52e70f8240abf6edaf360ddfc2..adf2bf1e187c341524e69bf7ddc7b8b2b449b9de 100644 (file)
--- a/include/asm-x86_64/segment.h
+++ b/include/asm-x86_64/segment.h
@@ -6,7 +6,7 @@
 #define __KERNEL_CS    0x10
 #define __KERNEL_DS    0x18
 
-#define __KERNEL32_CS   0x38
+#define __KERNEL32_CS   0x08
 
 /* 
  * we cannot use the same code segment descriptor for user and kernel