From: Carlos O'Donell <carlos@redhat.com>
To: "H.J. Lu" <hjl.tools@gmail.com>,
gnu-gabi@sourceware.org, Binutils <binutils@sourceware.org>
Subject: Re: RFC: Add SHT_GNU_PHDRS
Date: Mon, 01 Jan 2018 00:00:00 -0000 [thread overview]
Message-ID: <15814b22-551c-91a9-4b23-397e374cfd18@redhat.com> (raw)
In-Reply-To: <CAMe9rOoqcxZxPKgJn1JwG+ux4YRVbfWQBR=d9BOR3cfQgRn9QA@mail.gmail.com>
On 9/26/18 5:53 PM, H.J. Lu wrote:
> When -z separate-code is used to create executable, ld won't place any
> data in the code-only PT_LOAD segment. If there are no data sections
> placed before the code-only PT_LOAD segment, the program headers
> won't be mapped into any PT_LOAD segment. When the executable tries
> to access it (based on the program header address passed in AT_PHDR),
> it will lead to segfault.
>
> I am proposing
>
> #define SHT_GNU_PHDRS 0x6ffffff4 /* Dummy section for program header */
>
> This is a special read-only SHF_ALLOC zero-size data section. It is the
> first output section, which will force a data PT_LOAD segment with program
> header before the code-only PT_LOAD segment,
This seems like a huge hack to me. Either ld ensures that the page-aligned
start of the PT_LOAD mapping includes the program headers, or we have to
define SHT_GNU_PHDRS as having exactly that semantic and we need to clearly
explain what a static linker needs to do to accomplish this task. What you
have here needs more documentation.
--
Cheers,
Carlos.
next prev parent reply other threads:[~2018-09-27 3:25 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-01 0:00 H.J. Lu
2018-01-01 0:00 ` Carlos O'Donell [this message]
2018-01-01 0:00 ` H.J. Lu
[not found] ` <CAORpzuOWtHeqBLEE+MMN4-TZyp6Z1r-MdmyNv7Zj-BhxMstr=g@mail.gmail.com>
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Jan Beulich
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Szabolcs Nagy
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Cary Coutant
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Michael Matz
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Michael Matz
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` Cary Coutant
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Rich Felker
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Carlos O'Donell
2018-01-01 0:00 ` H.J. Lu
2018-01-01 0:00 ` Carlos O'Donell
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