[Morello] Pad section alignment to account for capability range format

[Morello] Pad section alignment to account for capability range format

The capability format has limitations on the alignment and length of
capability bounds and are subject to rounding.  Add alignment and
padding at the boundaries of such long (typically >16M) sections so
that any capabilities referencing these sections do not end up
overlapping into neighbouring sections.

There are two cases where this is in use.  The first and most
important due to the current implementation is the range for PCC,
which needs to span all executable sections and all PLT and GOT
sections.  The other case is for linker and ldscript defined symbols
that may be used in dynamic relocations.

bfd/ChangeLog:

2020-10-20  Siddhesh Poyarekar  <siddesh.poyarekar@arm.com>

	* elfnn-aarch64.c (elf_aarch64_link_hash_table): New member.
	(section_start_symbol, c64_valid_cap_range, exponent): Move
	up.
	(sec_change_queue): New structure.
	(queue_section_padding, record_section_change,
	elfNN_c64_resize_sections): New functions.
	(bfd_elfNN_aarch64_init_maps): Add info argument.  Adjust
	callers.
	* elfxx-aarch64.h (bfd_elf64_aarch64_init_maps,
	bfd_elf32_aarch64_init_maps): Add info argument.
	(elf64_c64_resize_sections, elf32_c64_resize_sections): New
	function declarations.

ld/ChangeLog:

2020-10-20  Siddhesh Poyarekar  <siddesh.poyarekar@arm.com>

	* emultempl/aarch64elf.em (elf64_c64_pad_section): New
	function.
	(gld${EMULATION_NAME}_after_allocation): Resize C64 sections.
	* ldlang.c (lang_add_newdot): New function.
	* ldlang.h (lang_add_newdot): New function declaration.
	* testsuite/ld-aarch64/aarch64-elf.exp: Add new test.
	* testsuite/ld-aarch64/morello-sec-round.d: New file.
	* testsuite/ld-aarch64/morello-sec-round.ld: New file.
	* testsuite/ld-aarch64/morello-sec-round.s: New file.