From: "H.J. Lu" <hjl.tools@gmail.com>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>,
"richard.henderson@linaro.org" <richard.henderson@linaro.org>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [RESEND PATCH] Makeconfig: Set pie-ccflag to -fPIE by default
Date: Fri, 26 Aug 2022 12:02:55 -0700 [thread overview]
Message-ID: <CAMe9rOoE1Fd0sO5foQcL3tehmsRPuC0XssamMdvTLzpQ3v6c6g@mail.gmail.com> (raw)
In-Reply-To: <AM5PR0801MB166829B54CB7FBF6AF83D6EF83759@AM5PR0801MB1668.eurprd08.prod.outlook.com>
On Fri, Aug 26, 2022 at 11:39 AM Wilco Dijkstra via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> Hi,
>
> >> I recall that powerpc wanted to use -mcmodel=large, but it would require to
> >> adjust a lot of assembly implementations. Are we sure this change does not
> >> trigger any regression with current glibc code?
>
> I don't see significant differences in terms of codesize on AArch64, so the patch
> is fine. As Richard mentioned, it often doesn't make any difference if a function
> only uses a single global.
>
> However this exposes a bug: it appears all symbols, including hidden symbols,
> are always accessed via the GOT in libc.a even when they don't in libc.so. As a
> result PIE code quality is actually worse than PIC... This affects libc_single_threaded
Is this issue processor specific?
> and many uses of internal arrays etc.
>
> So it looks like we should not ignore hidden when building for PIE.
--
H.J.
next prev parent reply other threads:[~2022-08-26 19:03 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-26 18:39 Wilco Dijkstra
2022-08-26 19:02 ` H.J. Lu [this message]
2022-08-26 19:45 ` Richard Henderson
2022-08-26 20:11 ` H.J. Lu
2022-08-29 11:49 ` Wilco Dijkstra
2022-08-29 13:10 ` Florian Weimer
2022-08-29 15:27 ` Wilco Dijkstra
2022-08-29 15:27 ` Wilco Dijkstra
2022-08-29 19:43 ` H.J. Lu
2022-08-29 19:57 ` Fangrui Song
2022-09-05 8:58 ` Wilco Dijkstra
2022-09-15 21:45 ` Fangrui Song
2022-09-20 13:59 ` Wilco Dijkstra
2022-09-20 14:12 ` Florian Weimer
2022-09-20 16:00 ` Wilco Dijkstra
2022-09-20 22:02 ` Fangrui Song
-- strict thread matches above, loose matches on Subject: below --
2022-08-25 21:01 Richard Henderson
2022-08-26 12:32 ` Adhemerval Zanella Netto
2022-08-26 17:29 ` Richard Henderson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAMe9rOoE1Fd0sO5foQcL3tehmsRPuC0XssamMdvTLzpQ3v6c6g@mail.gmail.com \
--to=hjl.tools@gmail.com \
--cc=Wilco.Dijkstra@arm.com \
--cc=adhemerval.zanella@linaro.org \
--cc=libc-alpha@sourceware.org \
--cc=richard.henderson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).