PowerPC indirect calls to __tls_get_addr

It is possible to construct indirect calls to __tls_get_addr in
assembly that confuse TLS optimization.  (PowerPC gcc doesn't support
such calls, ignoring -mlongcall for __tls_get_addr.)  This patch fixes
the problem by requiring a TLSLD or TLSGD marker reloc before any insn
in an indirect call to __tls_get_addr will be optimized.  They also
need additional marker relocs defined in a later patch, so don't
expect the optimization to work just yet.  The point here is to
prevent mis-optimization of indirect calls without any marker relocs.

The presense of a marker reloc is tracked by a new bit in the tls_mask
field of ppc_link_hash_entry and the corresponding lgot_masks unsigned
char array for local symbols.  Since the field is only 8 bits, we've
run out of space.  However, tracking TLS use for variables, and
tracking IFUNC for functions are independent, and bits can be reused.
TLS_TLS is always set for TLS usage, so can be used to select the
meaning of the other bits.  This patch does that even for elf32-ppc.c
which hasn't yet run out of space in the field.

	* elf64-ppc.c (TLS_TLS, TLS_GD, TLS_LD, TLS_TPREL, TLS_DTPREL,
	TLS_TPRELGD, TLS_EXPLICIT):  Renumber.  Test TLS_TLS throughout
	file when other TLS flags are tested in a mask.
	(TLS_MARK, NON_GOT): Define.
	(PLT_IFUNC): Redefine, and test TLS_TLS throughout file as well.
	(update_local_sym_info): Don't create got entry when NON_GOT.
	(ppc64_elf_check_relocs): Pass NON_GOT with PLT_IFUNC.
	Set TLS_MARK.
	(get_tls_mask): Do toc lookup if tls_mask is just TLS_MARK.
	(ppc64_elf_relocate_section): Likewise.
	(ppc64_elf_tls_optimize): Don't attempt to optimize indirect
	__tls_get_addr calls lacking a marker reloc.
	* elf32-ppc.c (TLS_TLS, TLS_GD, TLS_LD, TLS_TPREL, TLS_DTPREL,
	TLS_TPRELGD): Renumber.  Update comment.
	(TLS_MARK, NON_GOT): Define.
	(PLT_IFUNC): Redefine, and test TLS_TLS throughout file as well.
	(update_local_sym_info): Don't create got entry when NON_GOT.
	(ppc_elf_check_relocs): Pass NON_GOT with PLT_IFUNC.
	Set TLS_MARK.
	(ppc_elf_tls_optimize): Don't attempt to optimize indirect
	__tls_get_addr calls lacking a marker reloc.

0 files changed, 0 insertions, 0 deletions