On Tue, Sep 03, 2024 at 03:41:49PM -0400, Liam R. Howlett wrote:

* Mark Brown [off-list ref] [240902 15:09]:

quoted

+static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
+{
+	if (vm_flags & VM_SHADOW_STACK)
+		return PAGE_SIZE;

Is PAGE_SIZE is enough?

It's what x86 currently uses so it'll be no worse off if it gets moved
to the generic code (there's a comment in the arch code explaing what's
needed there) and it's enough for arm64, we only do single record
pushes/pops or (optionally) writes to unconstrained addresses.