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Re: RFC: x86: Fall back to lazy binding for unrelocated IFUNC symbol [BZ #23240]
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Florian Weimer <fweimer at redhat dot com>
- Cc: "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 6 Jun 2018 07:50:12 -0700
- Subject: Re: RFC: x86: Fall back to lazy binding for unrelocated IFUNC symbol [BZ #23240]
- References: <20180526135209.GA23818@intel.com> <fbaa5916-fc89-0ab9-72ed-883a408eaad4@redhat.com> <CAMe9rOrKtM2t3khHZonNw_xpZ22Nj2BU1A-6_7eAa6nNaQGDDA@mail.gmail.com> <a34107c3-880e-c40b-98b2-8026e9e29acf@redhat.com> <d476f562-1f99-3817-7b86-788e3540a42a@redhat.com> <CAMe9rOoKECiA-0ZHFazLzzBtvHVmCdMzYaBfqsJwh0q2Qch07w@mail.gmail.com> <c311c003-8b33-6d40-26ac-062a9f3e79e5@redhat.com> <363168df-c501-9d28-446b-34ee33a11611@redhat.com>
On Wed, Jun 6, 2018 at 7:04 AM, Florian Weimer <fweimer@redhat.com> wrote:
> On 06/05/2018 09:24 PM, Florian Weimer wrote:
>>
>> On 05/28/2018 09:51 PM, H.J. Lu wrote:
>>>
>>> Here is the updated patch. It fails to back lazy binding only
>>> if GOT is writable.
>>
>>
>> I think this still sets a wrong incentive, as in “you need to have a
>> writable GOT for full forwards compatibility with future library evolution”.
>>
>> I think if we detect an IFUNC-based relocation against a
>> not-yet-fully-relocated object, we need to delay this relocation processing
>> and perform a second pass of all delayed relocations. I have a patch which
>> needs a little bit of work, but looks quite promising (to me at least).
>
>
> Here are my patches:
>
> https://sourceware.org/ml/libc-alpha/2018-06/msg00076.html
> https://sourceware.org/ml/libc-alpha/2018-06/msg00077.html
>
> I hope they address your needs.
Do you have a git branch I can use?
--
H.J.