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[SYSVABI64] Reserve dynamic tags used by memtagabielf64 and pauthabi64
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The alpha ELF extension documents define dynamic tags. To avoid
avoidable clashes with the main specification, mark the values
used as reserved.
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@smithp35
smithp35 committed Mar 15, 2024
1 parent 8d5e422 commit 0233ab1
Showing 1 changed file with 64 additions and 36 deletions.
100 changes: 64 additions & 36 deletions sysvabi64/sysvabi64.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@
.. _CPPABI64: https://developer.arm.com/docs/ihi0059/latest
.. _GCABI: https://itanium-cxx-abi.github.io/cxx-abi/abi.html
.. _LINUX_ABI: https://github.com/hjl-tools/linux-abi/wiki
.. _MemTagABIELF64: https://github.com/ARM-software/abi-aa/releases
.. _PAuthABIELF64: https://github.com/ARM-software/abi-aa/releases
.. _HWCAP: https://www.kernel.org/doc/html/latest/arm64/elf_hwcaps.html
.. _LSB: https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/book1.html
.. _SCO-ELF: http://www.sco.com/developers/gabi
Expand Down Expand Up @@ -206,6 +208,10 @@ Change History
| | | Added Dynamic linking content for GCS including |
| | | GNU_PROPERTY_AARCH64_FEATURE_1_GCS Feature Bit |
+------------+------------------------------+-------------------------------------------------------+
| 2024Q1 | 15\ :sup:`th` March 2024 | - In `Dynamic Section Tags`_, reserve tags |
| | | used by `PAuthABIELF64`_ and |
| | | - `MemTagABIELF64`_. |
+---------------+--------------------+--------------------------------------------------------------+

References
----------
Expand All @@ -214,31 +220,35 @@ This document refers to, or is referred to by, the following documents.

.. table::

+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| Ref | External reference or URL | Title |
+=============+==============================================================+=============================================================================+
| SYSVABI_ | Source for this document | System V Application Binary Interface (ABI) for the Arm 64-bit architecture |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| ARMARM_ | DDI 0487 | Arm Architecture Reference Manual Armv8 for Armv8-A architecture profile |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| AAPCS64_ | IHI 0055 | Procedure Call Standard for the Arm 64-bit Architecture |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| AAELF64_ | IHI 0056 | ELF for the Arm 64-bit Architecture (AArch64). |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| CPPABI64_ | IHI 0059 | C++ ABI for the Arm 64-bit Architecture |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| GCABI_ | https://itanium-cxx-abi.github.io/cxx-abi/abi.html | Generic C++ ABI |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| HWCAP_ | https://www.kernel.org/doc/html/latest/arm64/elf_hwcaps.html | Linux Kernel HWCAPs interface |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| LINUX_ABI_ | https://github.com/hjl-tools/linux-abi/wiki | Linux Extensions to gABI |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| LSB_ | https://refspecs.linuxbase.org/lsb.shtml | Linux Standards Base Core Functional Area |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| SCO-ELF_ | http://www.sco.com/developers/gabi/ | System V Application Binary Interface – DRAFT |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| SYM-VER_ | http://people.redhat.com/drepper/symbol-versioning | GNU Symbol Versioning |
+-------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| Ref | External reference or URL | Title |
+=================+==============================================================+=============================================================================+
| SYSVABI_ | Source for this document | System V Application Binary Interface (ABI) for the Arm 64-bit architecture |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| ARMARM_ | DDI 0487 | Arm Architecture Reference Manual Armv8 for Armv8-A architecture profile |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| AAPCS64_ | IHI 0055 | Procedure Call Standard for the Arm 64-bit Architecture |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| AAELF64_ | IHI 0056 | ELF for the Arm 64-bit Architecture (AArch64). |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| CPPABI64_ | IHI 0059 | C++ ABI for the Arm 64-bit Architecture |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| GCABI_ | https://itanium-cxx-abi.github.io/cxx-abi/abi.html | Generic C++ ABI |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| HWCAP_ | https://www.kernel.org/doc/html/latest/arm64/elf_hwcaps.html | Linux Kernel HWCAPs interface |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| LINUX_ABI_ | https://github.com/hjl-tools/linux-abi/wiki | Linux Extensions to gABI |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| LSB_ | https://refspecs.linuxbase.org/lsb.shtml | Linux Standards Base Core Functional Area |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| MemTagABIELF64_ | memtagabielf64 | MemTag Extension to ELF for the Arm 64-bit Architecture |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| PAuthABIELF64_ | pauthabielf64 | PAuth Extension to ELF for the Arm 64-bit Architecture |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| SCO-ELF_ | http://www.sco.com/developers/gabi/ | System V Application Binary Interface – DRAFT |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+
| SYM-VER_ | http://people.redhat.com/drepper/symbol-versioning | GNU Symbol Versioning |
+-----------------+--------------------------------------------------------------+-----------------------------------------------------------------------------+

Terms and Abbreviations
-----------------------
Expand Down Expand Up @@ -1710,24 +1720,40 @@ Custom PLTs
instructions, it must add both ``DT_AARCH64_BTI_PLT`` and
``DT_AARCH64_PAC_PLT`` tags to the dynamic section.

Dynamic Section
^^^^^^^^^^^^^^^
Dynamic Section Tags
^^^^^^^^^^^^^^^^^^^^

AArch64 specifies the following processor-specific dynamic array tags.

.. _`AArch64 specific dynamic array tags`:

.. table:: AArch64 specific dynamic array tags

+---------------------------+------------+--------+-------------------+-------------------+
| Name | Value | d\_un | Executable | Shared Object |
+===========================+============+========+===================+===================+
| DT\_AARCH64\_BTI\_PLT | 0x70000001 | d\_val | Platform specific | Platform Specific |
+---------------------------+------------+--------+-------------------+-------------------+
| DT\_AARCH64\_PAC\_PLT | 0x70000003 | d\_val | Platform specific | Platform Specific |
+---------------------------+------------+--------+-------------------+-------------------+
| DT\_AARCH64\_VARIANT\_PCS | 0x70000005 | d\_val | Platform specific | Platform Specific |
+---------------------------+------------+--------+-------------------+-------------------+
+--------------------------------+------------+--------+-------------------+-------------------+
| Name | Value | d\_un | Executable | Shared Object |
+================================+============+========+===================+===================+
| DT\_AARCH64\_BTI\_PLT | 0x70000001 | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| DT\_AARCH64\_PAC\_PLT | 0x70000003 | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| DT\_AARCH64\_VARIANT\_PCS | 0x70000005 | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `MemTagABIELF64`_ | 0x70000009 | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `MemTagABIELF64`_ | 0x7000000b | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `MemTagABIELF64`_ | 0x7000000c | d\_ptr | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `MemTagABIELF64`_ | 0x7000000d | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `MemTagABIELF64`_ | 0x7000000f | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `PAuthABIELF64`_ | 0x70000011 | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `PAuthABIELF64`_ | 0x70000012 | d\_ptr | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+
| RESERVED for `PAuthABIELF64`_ | 0x70000013 | d\_val | Platform specific | Platform Specific |
+--------------------------------+------------+--------+-------------------+-------------------+

``DT_AARCH64_BTI_PLT`` indicates PLTs enabled with Branch Target Identification
mechanism.
Expand All @@ -1742,6 +1768,8 @@ Pointer Authentication.
relocations that reference symbols marked with the ``STO_AARCH64_VARIANT_PCS``
flag set in their ``st_other`` field.

See `MemTagABIELF64`_ and `PAuthABIELF64`_ for details of reserved tags.

.. raw:: pdf
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