BOLT instrument failed on Aarch64

[qianwindz]

I compiled bolt on the architecture of aarch64 to optimize the shared libraries of arrch64. At present, I am unable to use perf to obtain data, so I used llvm-bolt- instrument - o, but the above error occurred. May I ask what the reason is for this? Is there a solution?

[llvmbot]

@llvm/issue-subscribers-bolt

Author: None (qianwindz)

 I compiled bolt on the architecture of aarch64 to optimize the shared libraries of arrch64. At present, I am unable to use perf to obtain data, so I used llvm-bolt<exec>- instrument - o<exec-bolt>, but the above error occurred. May I ask what the reason is for this? Is there a solution?

[paschalis-mpeis]

Hi @qianwindz,

You're using PAC-RET, which BOLT doesn't yet support. I will be closing this as duplicate of:

• [BOLT] perf2bolt fails on aarch64 due to an unsupported CFI opcode #80992
• BOLT instrumentation fails on aarch64 due to an unsupported CFI opcode OpNegateRAState #74833

Note that we are working to add support for this. Please have a look at @bgergely0 proposal:

• [RFC][BOLT][AArch64] Handle OpNegateRAState to enable optimizing binaries with pac-ret hardening)

Feel free to comment on the RFC or here. The latest patch that adds support is:

• [BOLT][AArch64] Handle OpNegateRAState to enable optimizing binaries with pac-ret hardening #120064

I encourage you to try it, however, it doesn't yet include support for instrumentation. TMU, it's in the lineup of Gergely.
As a workaround, if you can live without PAC-RET and understand the security implications, disable it with: -mbranch-protection=none

[peterwaller-arm]

Just to mention also for anyone finding it, -mbranch-protection=none is required for all code being statically linked into a binary, which might not be limited to the workload you are attempting to compile (i.e. its dependencies).

As an example, this means if you are attempting to statically link a binary on a distribution which provides runtimes and libraries with branch protection switched on, compiling the workload and its dependencies with -mbranch-protection=none would still be insufficient, because bolt may still have a problem with the branch protection compiled in to the runtimes, until it has full support for pac-ret.

[qianwindz]

Yes, I have encountered this problem, and it is truly a sad outcome