On 1/29/21 3:39 PM, Madhavan T. Venkataraman wrote:

- A separate register has to be reserved for holding the shadow stack
  pointer. The compiler (gcc) has to be changed to not use this register for
  other purposes. And we have to trust that there are no compiler bugs
  in this area. All assembly code that currently uses this register for
  anything needs to be reviewed and potentially changed. This includes
  all inline assembly code. BTW, I believe clang uses x18 for the shadow
  stack pointer register.

Actually, if the stack and the shadow stack are allocated so that they are
adjacent or at a fixed distance from each other, we don't need a separate
register. We can compute parallel stack addresses from stack addresses by
a simple calculation.

So, this is not an issue.

Madhavan

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