Re: [PATCH 4/4] arm: Enable ARM mode for armv6 strlen

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 13/04/2018 09:44, Phil Blundell wrote:
> On Fri, 2018-04-13 at 13:06 +0100, Ramana Radhakrishnan wrote:
>> That change coming in with the NaCl port makes sense to me. IIRC NaCl
>> wanted fixed length encodings, (thus )everything to be in Arm state
>> only : instructions that were "forbidden" / not allowed as part of
>> the
>> whole NaCl strategy for providing sand boxes including switching to
>> Thumb. I also seem to remember that they had stuff that checked
>> instructions in the binary were in a particular set and anything
>> outside was not considered to be a safe binary.
>>
>> Aha - https://developer.chrome.com/native-client/reference/sandbox_in
>> ternals/arm-32-bit-sandbox#arm-32-bit-sandbox
> 
> Ah, thanks, that makes sense.  In that case, given that the rest of the
> NaCl port was removed a year ago, maybe we should also remove this
> cruft.  I think that'd essentially mean reverting
> 4f510e3aeeeb3fd974a12a71789fa9c63ab8c6dd and similar commits.
> 
> p.
> 

I am not against reverting it, but it does not help the scenario of 
BZ#23031.  We need to define whether environments which thumb is
expected to be supported but it is not enabled by compiler flags
(-marm) and act accordingly by avoid building glibc in such cases.

If we define that is the desirable case, we can also cleanup the
ARM code path for armv7 memchr and strcmp.