[PATCH] D135276: [AArch64] Add support for the SEH opcode for return address signing

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo added a comment.

In D135276#3838357 <https://reviews.llvm.org/D135276#3838357>, @mstorsjo wrote:

> In D135276#3838355 <https://reviews.llvm.org/D135276#3838355>, @efriedma wrote:
>
>> I guess if you run Windows in a virtual machine on a computer with PAC instructions (like a Mac), you might theoretically have access to them?  I don't currently have a setup like that, though.
>
> Oh, thanks, that's a good hint, I'll try to dig around to see if I can find someone with such a setup to run some tests for me.

I did get hold of a person with such a setup, but apparently either the PAC extensions weren't visible in the VM guest, or the OS hadn't set up the signing keys, so after either `paciasp` or `pacibsp`, the return address was unchanged - so the experiment didn't teach us anything about how this bug affects code on future devices. :-( (I did verify that the same test binaries do show the expected changes if I run them in Wine on Linux on Graviton 3 though.)


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