tree 02e5262098e0aa10f0c8ec9cc7dbfe88c66ee35d
parent ff70091a955348af15b7fea00c66591f52c7b5c4
author gejin <ge.jin@intel.com> 1629966038 +0800
committer Copybara-Service <copybara-worker@google.com> 1629965760 -0700

[libunwind] Support stack unwind in CET environment

Control-flow Enforcement Technology (CET), published by Intel,
introduces shadow stack feature aiming to ensure a return from
a function is directed to where the function was called.
In a CET enabled system, each function call will push return
address into normal stack and shadow stack, when the function
returns, the address stored in shadow stack will be popped and
compared with the return address, program will fail if the 2
addresses don't match.
In exception handling, the control flow may skip some stack frames
and we must adjust shadow stack to avoid violating CET restriction.
In order to achieve this, we count the number of stack frames skipped
and adjust shadow stack by this number before jumping to landing pad.

Reviewed By: hjl.tools, compnerd, MaskRay
Differential Revision: https://reviews.llvm.org/D105968

Signed-off-by: gejin <ge.jin@intel.com>
GitOrigin-RevId: 21b25a1fb32ecd2e1f336123c2715f8ef1a49f97