[PATCH 4/5] x86-64: further tighten convert-load-reloc checking

[H.J. Lu]

On Mon, Feb 3, 2025 at 7:41 PM Jan Beulich <jbeulich@suse.com> wrote:
>
> REX2.M affects what insn we're actually dealing with, so we better check
> this to avoid transforming (future) insns we must not touch.
>
> --- a/bfd/elf64-x86-64.c
> +++ b/bfd/elf64-x86-64.c
> @@ -2282,14 +2282,14 @@ elf_x86_64_convert_load_reloc (bfd *abfd
>           if (to_reloc_pc32)
>             return true;
>
> -         if (opcode == 0x85)
> +         if (opcode == 0x85 && !(rex2 & (REX2_M << 4)))
>             {
>               /* Convert "test %reg, foo@GOTPCREL(%rip)" to
>                  "test $foo, %reg".  */
>               modrm = 0xc0 | (modrm & 0x38) >> 3;
>               opcode = 0xf7;
>             }
> -         else if ((opcode | 0x38) == 0x3b)
> +         else if ((opcode | 0x38) == 0x3b && !(rex2 & (REX2_M << 4)))
>             {
>               /* Convert "binop foo@GOTPCREL(%rip), %reg" to
>                  "binop $foo, %reg".  */
>

Please add a testcase to show it makes a difference.

Thanks.


-- 
H.J.