Re: ARM long branch stub: thumb

[Richard Earnshaw <rearnsha at arm dot com>]

On Fri, 2009-02-20 at 15:15 +0100, Christophe LYON wrote:

>  static const bfd_vma elf32_arm_stub_long_branch_v4t_thumb_arm[] =
>    {
> -    0x4e03b540,         /* push {r6, lr} */
> -                        /* ldr  r6, [pc, #12] */
> -    0x473046fe,         /* mov  lr, pc */
> -                        /* bx   r6 */
> -    0xe8bd4040,         /* pop  {r6, pc} */
> -    0xe12fff1e,         /* bx   lr */
> -    0x00000000,         /* dcd  R_ARM_ABS32(X) */
> +    0x46c04778,         /* bx   pc */
> +                        /* nop   */
> +    0xe51ff004,         /* ldr   pc, [pc, #-4] */
> +    0x00000000,         /* dcd   R_ARM_ABS32(X) */
>    };

Unless I've missed a correction going on elsewhere, this isn't going to
work for BE-8 mode. The rules for manipulating thumb and ARM opcodes are
different (swap-16 and swap-32 respectively), and the code has to know
what instructions are at each address (the old code wouldn't have that
problem as it was all Thumb code).