From: "H.J. Lu" <hjl.tools@gmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>
Subject: Re: [PATCH 1/3] x86: Initialize CPU info via IFUNC relocation [BZ 26203]
Date: Fri, 18 Sep 2020 07:18:52 -0700 [thread overview]
Message-ID: <CAMe9rOqDwrj5Jba2=y1HaZfs09-SQ3QRrsqF9XEQCASTxfD8jw@mail.gmail.com> (raw)
In-Reply-To: <87a6xn6v8u.fsf@oldenburg2.str.redhat.com>
On Fri, Sep 18, 2020 at 6:59 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > On Fri, Sep 18, 2020 at 1:06 AM Florian Weimer <fweimer@redhat.com> wrote:
> >>
> >> * H. J. Lu via Libc-alpha:
> >>
> >> > X86 CPU features in ld.so are initialized by init_cpu_features, which is
> >> > invoked by DL_PLATFORM_INIT from _dl_sysdep_start. But when ld.so is
> >> > loaded by static executable, DL_PLATFORM_INIT is never called.
> >>
> >> I don't think that's accurate. It's called from elf/dl-support.c in the
> >> static case. But I agree that it's too late in this case.
> >
> > I was referring to the ld.so case. elf/dl-support.c isn't used for ld.so.
>
> I missed that.
>
> You cannot use ld.so in a static executable because it is
> uninitialized/dormant.
>
> If you need functionality after static dlopen, it has to reside in
> libc.so.6, not the dynamic loader.
Here is the problem. static dlopen uses libc.so.6 which brings in ld.so
with _rtld_global and _rtld_global_ro via DT_NEEDED. My patch is
trying to deal with it to initialize CPU info in _rtld_global_ro in this case.
--
H.J.
next prev parent reply other threads:[~2020-09-18 14:19 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-12 13:44 [PATCH 0/3] ld.so: Add --list-tunables to print tunable values H.J. Lu
2020-09-12 13:44 ` [PATCH 1/3] x86: Initialize CPU info via IFUNC relocation [BZ 26203] H.J. Lu
2020-09-18 8:06 ` Florian Weimer
2020-09-18 13:55 ` H.J. Lu
2020-09-18 13:59 ` Florian Weimer
2020-09-18 14:18 ` H.J. Lu [this message]
2020-09-18 14:22 ` Florian Weimer
2020-09-18 14:30 ` H.J. Lu
2020-09-21 8:21 ` Florian Weimer
2020-09-21 11:31 ` H.J. Lu
2020-09-25 12:55 ` Florian Weimer
2020-09-12 13:44 ` [PATCH 2/3] Set tunable value as well as min/max values H.J. Lu
2020-09-18 8:29 ` Florian Weimer
2020-09-18 15:11 ` H.J. Lu
2020-09-12 13:44 ` [PATCH 3/3] ld.so: Add --list-tunables to print tunable values H.J. Lu
2020-09-18 8:13 ` Florian Weimer
2020-09-18 15:24 ` H.J. Lu
-- strict thread matches above, loose matches on Subject: below --
2020-07-12 14:24 [PATCH 0/3] " H.J. Lu
2020-07-12 14:24 ` [PATCH 1/3] x86: Initialize CPU info via IFUNC relocation [BZ 26203] H.J. Lu
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