This patch implements the following:
- Emit PACBTI-M build attributes in libunwind asm files
- Authenticate LR in DWARF32 using PACBTI
Use Armv8.1-M.Main PACBTI extension to authenticate the return address
(stored in the LR register) before moving it to the PC (IP) register.
The AUTG instruction is used with the candidate return address, the CFA,
and the authentication code that is retrieved from the saved
pseudo-register RA_AUTH_CODE.
- Authenticate LR in EHABI using PACBTI
Authenticate the contents of the LR register using Armv8.1-M.Main PACBTI
extension.
A new frame unwinding instruction is introduced (0xb4). This
instruction pops out of the stack the return address authentication
code, which is then used in conjunction with the SP and the next-to-be
instruction pointer to perform authentication.
This authentication code is popped into a new register,
UNW_ARM_PSEUDO_PAC, which is a pseudo-register.
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:
- Momchil Velikov
- Victor Campos
- Ties Stuij
Reviewed By: #libunwind, danielkiss, mstorsjo
Differential Revision: https://reviews.llvm.org/D112430
We've stopped doing it in libc++ for a while now because these names
would end up rotting as we move things around and copy/paste stuff.
This cleans up all the existing files so as to stop the spreading
as people copy-paste headers around.
_Unwind_ForcedUnwind is not mandated by the EHABI but for compatibilty
reasons adding so the interface to higher layers would be the same.
Dropping EHABI specific _Unwind_Stop_Fn definition since it is not defined by EHABI.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D89570
Moving Itanium and ArmEHABI specific implementations to dedicated files.
This is a NFC patch.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D106461
Ties Stuij