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From: Nick Clifton <nickc@redhat.com>
To: gnu-gabi@sourceware.org
Cc: "H.J. Lu" <hjl.tools@gmail.com>, Florian Weimer <fweimer@redhat.com>
Subject: RFA: Add a new gynamic tag: DT_GNU_GOT_PLT_END
Date: Mon, 01 Jan 2018 00:00:00 -0000	[thread overview]
Message-ID: <83d583d0-884e-4208-436e-5b25cbb6ce5a@redhat.com> (raw)
In-Reply-To: <CAMe9rOrFiHvUj4EeviT8UdA2b8b_FpiPofeNqRyWzNA9286ZNQ@mail.gmail.com>

Hi Guys,

  I would like to propose the addition of a new dynamic tag to the gABI:

#define DT_GNU_GOT_PLT_END 0x60000100

  This tag would have two effects:

    * Its presence in the dynamic section would indicate that the 
      .got.plt section is on its own in a page aligned region of
      memory.

  IE no other sections overlap the pages used by the .got.plt, and
  the section has been padded so that it ends on a page alignment
  boundary.

    * The value of the tag would give the address of the first
      byte beyond the end of the .got.plt.

  This means that the size of the .got.plt can be computed by 
  subtracting the value of the DT_PLTGOT tag from the DT_GNU_GOT_PLT_END
  tag.

  The practical use of this tag is to allow the dynamic linker to
  isolate the .got.plt section by changing the permissions on the pages
  that it occupies.

Cheers
  Nick

PS.  I did see that there are already two tags called DT_PLTPAD and
  DT_PLTPADSZ, but apparently these are used by Solaris for implementing
  text relocations with 30-bit displacements (R_SPARC_WDISP30).

       reply	other threads:[~2018-06-21 14:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <87sh5hadd6.fsf@redhat.com>
     [not found] ` <CAMe9rOrFiHvUj4EeviT8UdA2b8b_FpiPofeNqRyWzNA9286ZNQ@mail.gmail.com>
2018-01-01  0:00   ` Nick Clifton [this message]
2018-01-01  0:00     ` Cary Coutant
2018-01-01  0:00       ` Cary Coutant
2018-01-01  0:00       ` Florian Weimer
2018-01-01  0:00         ` Cary Coutant
2018-01-01  0:00           ` Florian Weimer
2018-01-01  0:00             ` Cary Coutant
2018-01-01  0:00               ` Florian Weimer
2018-01-01  0:00                 ` Cary Coutant
2018-01-01  0:00                   ` Florian Weimer

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