From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
Randy Dunlap <rdunlap@infradead.org>,
Bagas Sanjaya <bagasdotme@gmail.com>,
Jonathan Corbet <corbet@lwn.net>
Subject: [PATCH v3] ELF: document some de-facto PT_* ABI quirks
Date: Sat, 15 Apr 2023 20:37:29 +0300 [thread overview]
Message-ID: <88d3f1bb-f4e0-4c40-9304-3843513a1262@p183> (raw)
In-Reply-To: <87edp7jyu4.fsf@meer.lwn.net>
Turns out rules about PT_INTERP, PT_GNU_STACK and PT_GNU_PROPERTY
program headers are slightly different.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
v3: move to Documentation/userspace-api/
v2: integrate into documentation build system
Documentation/userspace-api/ELF.rst | 34 ++++++++++++++++++++++++++++++++++
Documentation/userspace-api/index.rst | 1 +
2 files changed, 35 insertions(+)
new file mode 100644
--- /dev/null
+++ b/Documentation/userspace-api/ELF.rst
@@ -0,0 +1,34 @@
+.. 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.
--- a/Documentation/userspace-api/index.rst
+++ b/Documentation/userspace-api/index.rst
@@ -23,6 +23,7 @@ place where this information is gathered.
spec_ctrl
accelerators/ocxl
ebpf/index
+ ELF
ioctl/index
iommu
iommufd
next prev parent reply other threads:[~2023-04-15 17:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-14 17:02 [PATCH] ELF: document some de-facto PT_* ABI quirks Alexey Dobriyan
2023-03-15 2:34 ` Randy Dunlap
2023-03-17 8:22 ` Bagas Sanjaya
2023-03-17 16:53 ` Alexey Dobriyan
2023-03-19 12:52 ` Bagas Sanjaya
2023-03-26 16:49 ` [PATCH v2] " Alexey Dobriyan
2023-03-26 19:51 ` Randy Dunlap
2023-03-29 16:40 ` Jonathan Corbet
2023-04-15 17:37 ` Alexey Dobriyan [this message]
2023-04-20 16:07 ` [PATCH v3] " Jonathan Corbet
2023-12-06 22:58 ` Kees Cook
2023-12-07 15:03 ` Eric W. Biederman
2023-12-10 11:45 ` Alexey Dobriyan
2023-12-10 22:58 ` Eric W. Biederman
2023-12-11 16:26 ` Alexey Dobriyan
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