In some cases, an architecture might wish its stacks to be aligned to a
boundary larger than THREAD_SIZE. For example, using an alignment of
double THREAD_SIZE can allow for stack overflows smaller than
THREAD_SIZE to be detected by checking a single bit of the stack
pointer.
This patch allows architectures to override the alignment of VMAP'd
stacks, by defining THREAD_ALIGN. Where not defined, this defaults to
THREAD_SIZE, as is the case today.
Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: linux-kernel@vger.kernel.org