[Buildroot] Fwd: [PATCH] arm: ensure symbol is a thumb symbol in new binutils

From: Romain Naour <romain.naour@gmail.com>
To: buildroot@busybox.net
Subject: [Buildroot] Fwd: [PATCH] arm: ensure symbol is a thumb symbol in new binutils
Date: Thu, 31 May 2018 23:16:19 +0200	[thread overview]
Message-ID: <1e9b8ffd-cc1d-2c39-e34a-d1e33f49a645@gmail.com> (raw)
In-Reply-To: <254af731-459b-1f1d-2d93-27c5a91e7bfb@redhat.com>

Hi Nick,

Le 31/05/2018 ? 15:00, Nick Clifton a ?crit?:
> Hi Romain,
> 
>>>   https://sourceware.org/bugzilla/show_bug.cgi?id=21458
>>
>> What's the status of this bug?
> 
> It was sidelined. :-(  Sorry.

No problem :-)

> 
>> Some users reported a runtime issue with the linux kernel boot for Cortex-M
>> target: https://bugs.buildroot.org/show_bug.cgi?id=11051
> 
> I think that part of the problem is that the kernel people are 
> asking for the (adr affecting part of the) patch to be reverted, 
> but they have not suggested a way to address the issue raised in
> the PR.  (From comment #6 onwards).

Yes, but it's a very difficult topic.
Did you have some feedback from ARM ?

> 
> One thing that did occur to me is that the adr handling code
> in the assembler does not check to see if the bottom bit has 
> already been set, so maybe this is part of the problem.  Are
> you able to test out an assembler patch and see if it makes
> a difference ?  

I'm not able to test this patch but I'm adding Christophe Priouzeau in Cc.
He use a stm32f429 system.

Christophe, it would be great if you can test this patch with your toolchain
based on Binutils 2.29.

> 
> diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
> index dbaf1627bb..c682ceabd3 100644
> --- a/gas/config/tc-arm.c
> +++ b/gas/config/tc-arm.c
> @@ -8423,7 +8423,7 @@ do_adr (void)
>        && inst.reloc.exp.X_add_symbol != NULL
>        && S_IS_DEFINED (inst.reloc.exp.X_add_symbol)
>        && THUMB_IS_FUNC (inst.reloc.exp.X_add_symbol))
> -    inst.reloc.exp.X_add_number += 1;
> +    inst.reloc.exp.X_add_number |= 1;
>  }
>  
>  /* This is a pseudo-op of the form "adrl rd, label" to be converted
> 
> If that does not help, then I think that the only thing to do is
> to add a command line option to control the behaviour of the ADR
> pseudo-op and a configure time switch to set the default for this
> option.

Ok, let's see the test result.

Thanks for your time,
Romain

> 
> Cheers
>   Nick
> 