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[aadwarf64] Add a character to the augmentation string for RA signing method #430

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Merged
kmclaughlin-arm merged 3 commits into from
Oct 8, 2026
Merged

[aadwarf64] Add a character to the augmentation string for RA signing method #430

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328931e
[aadwarf64] Add a character to the augmentation string for RA signing…
kmclaughlin-arm Sep 18, 2026
65bb49f
- Move statement about requiring a single method to the note section.
kmclaughlin-arm Sep 23, 2026
34e660d
- Clarify that the new mark only has meaning for DW_AARCH64_RA_SIGNED…
kmclaughlin-arm Sep 28, 2026
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12 changes: 11 additions & 1 deletion aadwarf64/aadwarf64.rst
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Expand Up @@ -592,7 +592,7 @@ This generates the following obligations on producers and consumers of CIEs:
cannot be used by any associated functions and their descendants. Although
these are not callee-saved, they are not callee-used either.)

This ABI defines two CIE augmentation characters that may appear as part of
This ABI defines three CIE augmentation characters that may appear as part of
a CIE augmentation string.

1. The character 'B' indicates that associated frames are using the B key for
Expand All @@ -601,12 +601,22 @@ a CIE augmentation string.
2. The character 'G' indicates that associated frames may modify MTE tags on
the stack space they use.
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3. The character 'N' indicates that associated frames are using non hint-space
FEAT_PAuth_LR instructions for return address signing.

.. note::

1. The mark on a frame recording that it may have set MTE tags other than the
stack background is information which can be used when unwinding.

2. The mark on a frame recording that it uses non hint-space instructions
for return address signing is information which can be used when unwinding.
This mark only has meaning when the PC value was used as a diversifier for
signing and will be ignored otherwise. If the mark is absent and the PC
value was used as a diversifier, this indicates that the hint-space PACM
instruction was used. It is required that a single method is used to sign
and authenticate a pointer.

.. raw:: pdf

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