On Fri, Nov 01, 2019 at 10:22:14AM +0100, Aurelien Jarno wrote:
>On 2019-10-30 00:17, Steve McIntyre wrote:
>> Source: glibc
>> Version: 2.28-10
>> Severity: important
>> Hi folks,
>> It looks like my old Arm ABI detection patch for ld.so is causing
>> problems for people using LLVM. I've been contacted by a developer,
>> referring to a mailing list thread:
>>   https://lists.llvm.org/pipermail/llvm-dev/2019-October/135993.html
>> It looks like the LLVM version of strip is more aggressive than the
>> GNU binutils version, and this is causing problems - it's stripping
>> the .ARM.attributes data and that's causing problems with our extra
>> checks for the Tag_ABI_VFP_args setting. Whether that's a valid thing
>> to do or not is an argument for another day, I think... However,
>> checking with the bzip2 binaries that the reporter provided I can see
>> that they have the right ABI flag in the ELF header but we're still
>> running the extra ABI check:
>> (sid-armhf)steve@mjolnir:~/abi$ LD_PRELOAD=./libbz2.so.all ./bzip2 
>> ERROR: ld.so: object './libbz2.so.all' from LD_PRELOAD cannot be preloaded 
>> (cannot open shared object file): ignored.
>> bzip2: I won't write compressed data to a terminal.
>> bzip2: For help, type: `bzip2 --help'.
>> (sid-armhf)steve@mjolnir:~/abi$ readelf -a libbz2.so.all | grep "^  Flags"
>>   Flags:                             0x5000400, Version5 EABI, hard-float ABI
>> I think this is wrong, and I can't think of why I didn't find this
>> earlier when I was working in this area. :-/
>> So: I think we have two sensible options:
>> 1. I find time now to fix up ld.so to only do the extra check here if
>>    we think it's needed
>> OR
>> 2. Just remove the patch for extra check here - it was always the plan
>>    that this would go away after a while once people were unlikely to
>>    still be running binaries from the pre ELF-header toolchains.
>> Checking history, I can see that the binutils changes for those ELF
>> header changes landed in Debian back in Nov 2012. (Wow, time
>> flies!). Given that, I'd now be strongly in favour of just dropping the
>> patch in
>> debian/patches/arm/unsubmitted-ldso-abi-check.diff
>> as it's now safely obsolete. What do others think?
>Given this patch is not needed anymore, I also thing it's the way to do.
>It caused us issue in the past, so i'll be very happy to see it going

ACK. I did want to keep it around for a while for safety, and that
period is clearly done. Thanks for your help with this! 

Steve McIntyre, Cambridge, UK.                                st...@einval.com
You raise the blade, you make the change... You re-arrange me 'til I'm sane...

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