On Tue, 2023-02-21 at 09:31 +0100, David Hildenbrand wrote:

quoted

quoted

Why not modify is_stack_mapping() ?

It kind of sticks out a little in this conditional, but
is_stack_mapping() has this comment:
/*
   * Stack area - automatically grows in one direction
   *
   * VM_GROWSUP / VM_GROWSDOWN VMAs are always private anonymous:
   * do_mmap() forbids all other combinations.
   */

Shadow stack don't grow, so it doesn't quite fit. There used to be
an
is_shadow_stack_mapping(), but it was removed because all that was
needed (for the time being) was the simple bitwise AND:

https://lore.kernel.org/lkml/804adbac-61e6-0fd2-f726-5735fb290199@intel.com/ (local)

As there is only a single user of is_stack_mapping(), I'd simply
have 
adjusted the doc of is_stack_mapping() to include shadow stacks.

Ok, I'll update the comment and add it there.