kbuild/extable: Hook up sortextable into the build system.

Define a config variable BUILDTIME_EXTABLE_SORT to control build time
sorting of the kernel's exception table.

Patch Makefile to do the sorting when BUILDTIME_EXTABLE_SORT is
selected.

Signed-off-by: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1334872799-14589-4-git-send-email-ddaney.cavm@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Makefile

@@ -784,6 +784,10 @@ quiet_cmd_vmlinux_version = GEN     .version
 quiet_cmd_sysmap = SYSMAP
       cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap
 
+# Sort exception table at build time
+quiet_cmd_sortextable = SORTEX
+      cmd_sortextable = $(objtree)/scripts/sortextable
+
 # Link of vmlinux
 # If CONFIG_KALLSYMS is set .version is already updated
 # Generate System.map and verify that the content is consistent
@@ -796,6 +800,12 @@ define rule_vmlinux__
 	$(call cmd,vmlinux__)
 	$(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
 
+	$(if $(CONFIG_BUILDTIME_EXTABLE_SORT),				\
+	  $(Q)$(if $($(quiet)cmd_sortextable),				\
+	    echo '  $($(quiet)cmd_sortextable)  vmlinux' &&)		\
+	  $(cmd_sortextable)  vmlinux)
+
+
 	$(Q)$(if $($(quiet)cmd_sysmap),                                      \
 	  echo '  $($(quiet)cmd_sysmap)  System.map' &&)                     \
 	$(cmd_sysmap) $@ System.map;                                         \

init/Kconfig

@@ -27,6 +27,9 @@ config IRQ_WORK
 	bool
 	depends on HAVE_IRQ_WORK
 
+config BUILDTIME_EXTABLE_SORT
+	bool
+
 menu "General setup"
 
 config EXPERIMENTAL