[PATCH 2/2] aarch64: Support PLT with PAC

[Szabolcs Nagy]

Add pointer authentication code to the function pointers in PLTGOT if
DT_AARCH64_PAC_PLT is set on an elf binary. In such binaries the PLT
authenticates the pointer loaded from the GOT entry. This is only valid
in LP64 binaries and only useful when the PLTGOT is writable at runtime,
i.e. with lazy binding.

Note: TLS descriptors are not protected, the static linker should ensure
that GOT entries with TLSDESC relocations are read-only, i.e. they are
not lazy resolved.

2019-06-20  Szabolcs Nagy  <szabolcs.nagy@arm.com>

	* sysdeps/aarch64/dl-machine.h (set_jump_slot): Define.
	(elf_machine_fixup_plt): Use set_jump_slot.
	(elf_machine_rela): Likewise.
	(elf_machine_lazy_rel): Likewise.
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