x86, realmode: 16-bit real-mode code support for relocs tool

commit 6520fe55 upstream.

A new option is added to the relocs tool called '--realmode'.
This option causes the generation of 16-bit segment relocations
and 32-bit linear relocations for the real-mode code. When
the real-mode code is moved to the low-memory during kernel
initialization, these relocation entries can be used to
relocate the code properly.

In the assembly code 16-bit segment relocations must be relative
to the 'real_mode_seg' absolute symbol. Linear relocations must be
relative to a symbol prefixed with 'pa_'.

16-bit segment relocation is used to load cs:ip in 16-bit code.
Linear relocations are used in the 32-bit code for relocatable
data references. They are declared in the linker script of the
real-mode code.

The relocs tool is moved to arch/x86/tools/relocs.c, and added new
target archscripts that can be used to build scripts needed building
an architecture.  be compiled before building the arch/x86 tree.

[ hpa: accelerating this because it detects invalid absolute
  relocations, a serious bug in binutils 2.22.52.0.x which currently
  produces bad kernels. ]
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.comSigned-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
[bwh: Backported to 3.2:
 - Adjust context (no archheaders; no insn_sanity)
 - Expand put_unaligned_le32()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

Makefile

@@ -442,7 +442,7 @@ asm-generic:
 
 no-dot-config-targets := clean mrproper distclean \
 			 cscope gtags TAGS tags help %docs check% coccicheck \
-			 include/linux/version.h headers_% \
+			 include/linux/version.h headers_% archscripts \
 			 kernelversion %src-pkg
 
 config-targets := 0
@@ -979,7 +979,7 @@ prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \
                    include/config/auto.conf
 	$(cmd_crmodverdir)
 
-archprepare: prepare1 scripts_basic
+archprepare: archscripts prepare1 scripts_basic
 
 prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
@@ -1046,8 +1046,11 @@ hdr-inst := -rR -f $(srctree)/scripts/Makefile.headersinst obj
 # If we do an all arch process set dst to asm-$(hdr-arch)
 hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)
 
+PHONY += archscripts
+archscripts:
+
 PHONY += __headers
-__headers: include/linux/version.h scripts_basic asm-generic FORCE
+__headers: include/linux/version.h scripts_basic asm-generic archscripts FORCE
 	$(Q)$(MAKE) $(build)=scripts build_unifdef
 
 PHONY += headers_install_all

arch/x86/Makefile

@@ -117,6 +117,9 @@ KBUILD_CFLAGS += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,)
 KBUILD_CFLAGS += $(mflags-y)
 KBUILD_AFLAGS += $(mflags-y)
 
+archscripts:
+	$(Q)$(MAKE) $(build)=arch/x86/tools relocs
+
 ###
 # Kernel objects
 

arch/x86/boot/compressed/Makefile

@@ -31,13 +31,12 @@ OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)
 
+targets += vmlinux.bin.all vmlinux.relocs
 
-targets += vmlinux.bin.all vmlinux.relocs relocs
-hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs
-
+CMD_RELOCS = arch/x86/tools/relocs
 quiet_cmd_relocs = RELOCS  $@
-      cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
-$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
+      cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
+$(obj)/vmlinux.relocs: vmlinux FORCE
 	$(call if_changed,relocs)
 
 vmlinux.bin.all-y := $(obj)/vmlinux.bin

arch/x86/tools/.gitignore

+relocs

arch/x86/tools/Makefile

@@ -29,3 +29,6 @@ HOSTCFLAGS_test_get_len.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/
 # Dependencies are also needed.
 $(obj)/test_get_len.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
 
+HOST_EXTRACFLAGS += -I$(srctree)/tools/include
+hostprogs-y	+= relocs
+relocs: $(obj)/relocs

scripts/Makefile

@@ -8,6 +8,8 @@
 # conmakehash:	 Create arrays for initializing the kernel console tables
 # docproc:       Used in Documentation/DocBook
 
+HOST_EXTRACFLAGS += -I$(srctree)/tools/include
+
 hostprogs-$(CONFIG_KALLSYMS)     += kallsyms
 hostprogs-$(CONFIG_LOGO)         += pnmtologo
 hostprogs-$(CONFIG_VT)           += conmakehash