powerpc/32s: Fix module loading failure when VMALLOC_END is over 0xf0000000

In is_module_segment(), when VMALLOC_END is over 0xf0000000,
ALIGN(VMALLOC_END, SZ_256M) has value 0.

In that case, addr >= ALIGN(VMALLOC_END, SZ_256M) is always
true then is_module_segment() always returns false.

Use (ALIGN(VMALLOC_END, SZ_256M) - 1) which will have
value 0xffffffff and will be suitable for the comparison.

Fixes: c4964331 ("powerpc/32s: Only leave NX unset on segments used for modules")
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/09fc73fe9c7423c6b4cf93f93df9bb0ed8eefab5.1597994047.git.christophe.leroy@csgroup.eu

arch/powerpc/mm/book3s32/mmu.c

@@ -194,12 +194,12 @@ static bool is_module_segment(unsigned long addr)
 #ifdef MODULES_VADDR
 	if (addr < ALIGN_DOWN(MODULES_VADDR, SZ_256M))
 		return false;
-	if (addr >= ALIGN(MODULES_END, SZ_256M))
+	if (addr > ALIGN(MODULES_END, SZ_256M) - 1)
 		return false;
 #else
 	if (addr < ALIGN_DOWN(VMALLOC_START, SZ_256M))
 		return false;
-	if (addr >= ALIGN(VMALLOC_END, SZ_256M))
+	if (addr > ALIGN(VMALLOC_END, SZ_256M) - 1)
 		return false;
 #endif
 	return true;