ARMv4 EABi support

[Paul Brook]

The ARM EABI requires that code be interworking safe. However ARMv4 cores do 
not support the BX instruction necessary for this.  The solution to this is 
the R_ARM_V4BX relocation, which allows the static linker to turn interworked 
v4t code into plain v4 code.

The attached patch makes gas generate these relocations. In addition it adds 
a --fix-v4bx option that allows bx on ARMv4 cores.  The name of this option 
was chosen to match the existing linker option.

I've also added a new --with-v4bx-interworking option.  This is aimed at 
systems like Debian where running the same binaries/shared libraries on all 
systems is important.  As described in the documentation, this replaces a bx 
instruction with a branch to a veneer that supports both interworking and 
ARMv4 simultaneously.

Tested on arm-none-eabi and arm-elf
Applied to CVS head.

Paul

2008-02-20  Paul Brook  <paul@codesourcery.com>

	ld/
	* emultempl/armelf.em (OPTION_FIX_V4BX_INTERWORKING): Define.
	(PARSE_AND_LIST_LONGOPTS): Add fix-v4bx-interworking.
	(PARSE_AND_LIST_OPTIONS): Ditto.
	(PARSE_AND_LIST_ARGS_CASES): Handle OPTION_FIX_V4BX_INTERWORKING.
	* emulparams/armelf.sh (OTHER_TEXT_SECTIONS): Add .v4_bx.
	* emulparams/armelf_linux.sh (OTHER_TEXT_SECTIONS): Ditto.
	* emulparams/armnto.sh (OTHER_TEXT_SECTIONS): Ditto.
	* ld.texinfo: Document --fix-v4bx-interworking.

	ld/testsuite/
	* ld-arm/armv4-bx.d: New test.
	* ld-arm/armv4-bx.s: New test.
	* ld-arm/arm.ld: Add .v4bx.
	* ld-arm/arm-elf.exp: Add armv4-bx.

	gas/testsuite/
	* gas/arm/thumb.d: Exclude EABI targets.
	* gas/arm/arch4t.d: Exclude EABI targts.
	* gas/arm/v4bx.d: New test.
	* gas/arm/v4bx.s: New test.
	* gas/arm/thumb-eabi.d: New test.
	* gas/arm/arch4t-eabi.d: New test.

	gas/
	* config/tc-arm.c (fix_v4bx): New variable.
	(do_bx): Generate V4BX relocations.
	(md_assemble): Allow bx on v4 codes when fix_v4bx.
	(md_apply_fix): Handle BFD_RELOC_ARM_V4BX.
	(tc_gen_reloc): Ditto.
	(OPTION_FIX_V4BX): Define.
	(md_longopts): Add fix-v4bx.
	(md_parse_option): Handle OPTION_FIX_V4BX.
	(md_show_usage): Document --fix-v4bx.
	* doc/c-arm.texi: Document --fix-v4bx.

	bfd/
	* reloc.c: Add BFD_RELOC_ARM_V4BX.
	* elf32-arm.c (elf32_arm_reloc_map): Add BFD_RELOC_ARM_V4BX.
	(ARM_BX_GLUE_SECTION_NAME, ARM_BX_GLUE_SECTION_NAME): Define.
	(elf32_arm_link_hash_table): Add bx_glue_size and bx_glue_offset.
	Update comment for fix_v4bx.
	(elf32_arm_link_hash_table_create): Zero bx_glue_size and
	bx_glue_offset.
	(ARM_BX_VENEER_SIZE, armbx1_tst_insn, armbx2_moveq_insn,
	armbx3_bx_insn): New.
	(bfd_elf32_arm_allocate_interworking_sections): Allocate BX veneer
	section.
	(bfd_elf32_arm_add_glue_sections_to_bfd): Ditto.
	(bfd_elf32_arm_process_before_allocation): Record BX veneers.
	(record_arm_bx_glue, elf32_arm_bx_glue): New functions.
	(elf32_arm_final_link_relocate): Handle BX veneers.
	(elf32_arm_output_arch_local_syms): Output mapping symbol for .v4_bx.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.
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