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Introduce SHF_AARCH64_LARGE section flag #326

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Introduce SHF_AARCH64_LARGE section flag #326

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3 changes: 3 additions & 0 deletions aaelf64/aaelf64.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -644,6 +644,9 @@ The defined processor-specific section attribute flags are listed in the followi
+--------------------------+----------------+----------------------------------------------------+
| Name | Value | Comment |
+==========================+================+====================================================+
| ``SHF_AARCH64_LARGE`` | ``0x10000000`` | The contents of this section contains large data |
| | | and is placed on the outer edges of the binary |
+--------------------------+----------------+----------------------------------------------------+
| ``SHF_AARCH64_PURECODE`` | ``0x20000000`` | The contents of this section contains only program |
| | | instructions and no program data |
+--------------------------+----------------+----------------------------------------------------+
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14 changes: 8 additions & 6 deletions sysvabi64/sysvabi64.rst
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Expand Up @@ -817,6 +817,7 @@ does not have a maximum size limit.

Data is defined as large data if any of the following are true:

- The data is in section with section flag ``SHF_AARCH64_LARGE``.
- The data is >= 64 KiB in size.
- The data is of unknown size.
- The data will be represented by an unallocated common block, described by a
Expand All @@ -825,12 +826,13 @@ Data is defined as large data if any of the following are true:
All other data is small data.

Large data is placed in sections with an ``l`` prefix, for example ``.lbss``,
``.ldata`` and ``.lrodata``. Both small and large RELRO data are placed in
``.data.rel.ro`` as many loaders only support one ``PT_GNU_RELRO`` program
header. At static link time the large data sections must be placed after all
small data sections. If it is the last small data section, the static linker
allocates storage for ``SHN_COMMON`` symbols at the end of the ``bss``
section. Otherwise they are allocated in ``lbss``.
``.ldata`` and ``.lrodata``. Additionally, they all have ``SHF_AARCH64_LARGE``
section flag. Both small and large RELRO data are placed in ``.data.rel.ro``
as many loaders only support one ``PT_GNU_RELRO`` program header. At static
link time the large data sections must be placed after all small data sections.
If it is the last small data section, the static linker allocates storage for
``SHN_COMMON`` symbols at the end of the ``bss`` section. Otherwise they are
allocated in ``lbss``.

Sample code sequences for code models
-------------------------------------
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