arm, cris, mips, sparc, powerpc, um, xtensa: fix build with bash 4.0

Albin Tonnerre <albin.tonnerre@free-electrons.com> reported:

    Bash 4 filters out variables which contain a dot in them.
    This happends to be the case of CPPFLAGS_vmlinux.lds.
    This is rather unfortunate, as it now causes
    build failures when using SHELL=/bin/bash to compile,
    or when bash happens to be used by make (eg when it's /bin/sh)

Remove the common definition of CPPFLAGS_vmlinux.lds by
pushing relevant stuff to either Makefile.build or the
arch specific kernel/Makefile where we build the linker script.

This is also nice cleanup as we move the information out where
it is used.

Notes for the different architectures touched:

arm - we use an already exported symbol
cris - we use a config symbol aleady available
       [Not build tested]
mips - the jiffies complexity has moved to vmlinux.lds.S where we need it.
       Added a few variables to CPPFLAGS - they are only used by
       the linker script.
       [Not build tested]
powerpc - removed assignment that is not needed
          [not build tested]
sparc - simplified it using $(BITS)
um - introduced a few new exported variables to deal with this
xtensa - added options to CPP invocation
         [not build tested]

Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

arch/um/Makefile

@@ -96,11 +96,10 @@ CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,)
 	$(call cc-option, -fno-stack-protector,) \
 	$(call cc-option, -fno-stack-protector-all,)
 
-CONFIG_KERNEL_STACK_ORDER ?= 2
-STACK_SIZE := $(shell echo $$[ 4096 * (1 << $(CONFIG_KERNEL_STACK_ORDER)) ] )
-
-CPPFLAGS_vmlinux.lds = -U$(SUBARCH) -DSTART=$(START) -DELF_ARCH=$(ELF_ARCH) \
-	-DELF_FORMAT="$(ELF_FORMAT)" -DKERNEL_STACK_SIZE=$(STACK_SIZE)
+# Options used by linker script
+export LDS_START      := $(START)
+export LDS_ELF_ARCH   := $(ELF_ARCH)
+export LDS_ELF_FORMAT := $(ELF_FORMAT)
 
 # The wrappers will select whether using "malloc" or the kernel allocator.
 LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc

arch/um/kernel/Makefile

@@ -3,6 +3,9 @@
 # Licensed under the GPL
 #
 
+CPPFLAGS_vmlinux.lds := -U$(SUBARCH) -DSTART=$(LDS_START) \
+                        -DELF_ARCH=$(LDS_ELF_ARCH)        \
+                        -DELF_FORMAT=$(LDS_ELF_FORMAT)
 extra-y := vmlinux.lds
 clean-files :=
 

arch/um/kernel/vmlinux.lds.S

@@ -1,3 +1,6 @@
+
+KERNEL_STACK_SIZE = 4096 * (1 << CONFIG_KERNEL_STACK_ORDER);
+
 #ifdef CONFIG_LD_SCRIPT_STATIC
 #include "uml.lds.S"
 #else