Re: [PATCH v19 00/27] riscv control-flow integrity for usermode

* Deepak Gupta:

In case of shadow stack, it similar situation. If enabled compiler decides to insert sspush and sspopchk. They necessarily won't be prologue or epilogue but somewhere in function body as deemed fit by compiler, thus increasing the complexity of runtime patching.

More so, here are wishing for kernel to do this patching for usermode vDSO when there is no guarantee of such of rest of usermode (which if was compiled with shadow stack would have faulted before vDSO's sspush/sspopchk if ran on pre-zimop hardware)

I think this capability is desirable so that you can use a distribution kernel during CFI userspace bringup.

Thanks, Florian