x86: fix asm warning in head_32.S

On Mon, May 19, 2008 at 04:10:02PM -0700, Linus Torvalds wrote:
> It also causes these warnings on 32-bit PAE:
>
> 	  AS      arch/x86/kernel/head_32.o
> 	arch/x86/kernel/head_32.S: Assembler messages:
> 	arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
> 	arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed
>
> and I do not see why (the end result seems to be identical).

Fix head_32.S gcc bignum warnings when CONFIG_PAE=y.

    arch/x86/kernel/head_32.S: Assembler messages:
    arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
    arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed

The assembler was stumbling over the 64-bit constant 0x100000000 in the
KPMDS #define.

Testing: a cmp(1) on head_32.o before and after shows the binary is unchanged.

Signed-off-by: Joe Korty <[email protected]
Cc: Hugh Dickins <[email protected]>
Cc: Theodore Tso <[email protected]>
Cc: Gabriel C <[email protected]>
Cc: Keith Packard <[email protected]>
Cc: "Pallipadi Venkatesh" <[email protected]>
Cc: Eric Anholt <[email protected]>
Cc: "Siddha Suresh B" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: "Barnes Jesse" <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Linus Torvalds <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

Author: Joe Korty

arch/x86/kernel/head_32.S

@@ -189,7 +189,7 @@ default_entry:
 	 * this stage.
 	 */
 
-#define KPMDS ((0x100000000-__PAGE_OFFSET) >> 30) /* Number of kernel PMDs */
+#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
 
 	xorl %ebx,%ebx				/* %ebx is kept at zero */