tree 9300e072736fd4fb96a62d3f1cde3b55e38fd500
parent 4db92934dee4150a6a15de9240cb318685250597
author Ties Stuij <ties.stuij@arm.com> 1638788410 +0000
committer Copybara-Service <copybara-worker@google.com> 1638789063 -0800

[ARM] Implement setjmp BTI placement for PACBTI-M

This patch intends to guard indirect branches performed by longjmp
by inserting BTI instructions after calls to setjmp.

Calls with 'returns-twice' are lowered to a new pseudo-instruction
named t2CALL_BTI that is later expanded to a bundle of {tBL,t2BTI}.

This patch is part of a series that adds support for the PACBTI-M extension of
the Armv8.1-M architecture, as detailed here:

https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/armv8-1-m-pointer-authentication-and-branch-target-identification-extension

The PACBTI-M specification can be found in the Armv8-M Architecture Reference
Manual:

https://developer.arm.com/documentation/ddi0553/latest

The following people contributed to this patch:

- Alexandros Lamprineas
- Ties Stuij

Reviewed By: labrinea

Differential Revision: https://reviews.llvm.org/D112427

GitOrigin-RevId: 0fbb17458a01a6b388fc67661ffb92969503e977