ARM long branch stub: thumb

[Christophe LYON]

On 20.02.2009 16:23, Richard Earnshaw wrote:
> 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).

Damned!

If I look at arm_build_one_stub, I can see that only put_arm_insn is 
use, whatever the stub being encoded. So there is a problem with any 
stub using thumb, isn't it?

Christophe.