On Tue, Oct 3, 2023, at 18:35, Sohil Mehta wrote:

On 9/14/2023 11:58 AM, Sohil Mehta wrote:

quoted

commit c35559f94ebc ("x86/shstk: Introduce map_shadow_stack syscall")
recently added support for map_shadow_stack() but it is limited to x86
only for now. There is a possibility that other architectures (namely,
arm64 and RISC-V), that are implementing equivalent support for shadow
stacks, might need to add support for it.

Independent of that, reserving arch-specific syscall numbers in the
syscall tables of all architectures is good practice and would help
avoid future conflicts. map_shadow_stack() is marked as a conditional
syscall in sys_ni.c. Adding it to the syscall tables of other
architectures is harmless and would return ENOSYS when exercised.

Note, map_shadow_stack() was assigned #453 during the merge process
since #452 was taken by fchmodat2().

For Powerpc, map it to sys_ni_syscall() as is the norm for Powerpc
syscall tables.

For Alpha, map_shadow_stack() takes up #563 as Alpha still diverges from
the common syscall numbering system in the other architectures.

Link: https://lore.kernel.org/lkml/20230515212255.GA562920@debug.ba.rivosinc.com/ (local)
Link: https://lore.kernel.org/lkml/b402b80b-a7c6-4ef0-b977-c0f5f582b78a@sirena.org.uk/ (local)

Signed-off-by: Sohil Mehta <redacted>
---

Gentle ping...

Are there any additional comments? It applies cleanly on 6.6-rc4.

Or does it seem ready to be merged? It has the following
acknowledgements until now:

Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

If you like, I can pick this up for 6.7 through the asm-generic
tree. If you think this should be part of 6.6, I would suggest
to merge it through the tree that originally contained the
syscall code.

      Arnd