Commit 5c2c34a4 authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Jonathan Corbet
Browse files

ELF: document some de-facto PT_* ABI quirks 



Turns out rules about PT_INTERP, PT_GNU_STACK and PT_GNU_PROPERTY
program headers are slightly different.

Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Link: https://lore.kernel.org/r/88d3f1bb-f4e0-4c40-9304-3843513a1262@p183


Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 4de3790a

Documentation/userspace-api/ELF.rst

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.. SPDX-License-Identifier: GPL-2.0



=================================

Linux-specific ELF idiosyncrasies

=================================



Definitions

===========



"First" program header is the one with the smallest offset in the file:

e_phoff.



"Last" program header is the one with the biggest offset in the file:

e_phoff + (e_phnum - 1) * sizeof(Elf_Phdr).



PT_INTERP

=========



First PT_INTERP program header is used to locate the filename of ELF

interpreter. Other PT_INTERP headers are ignored (since Linux 2.4.11).



PT_GNU_STACK

============



Last PT_GNU_STACK program header defines userspace stack executability

(since Linux 2.6.6). Other PT_GNU_STACK headers are ignored.



PT_GNU_PROPERTY

===============



ELF interpreter's last PT_GNU_PROPERTY program header is used (since

Linux 5.8). If interpreter doesn't have one, then the last PT_GNU_PROPERTY

program header of an executable is used. Other PT_GNU_PROPERTY headers

are ignored.

Documentation/userspace-api/index.rst

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@@ -23,6 +23,7 @@ place where this information is gathered. 
   spec_ctrl

   accelerators/ocxl

   ebpf/index

   ELF

   ioctl/index

   iommu

   iommufd