A new macro Z_THREAD_STACK_OBJ_ALIGN() defines the alignment
of the lowest memory address of a stack object.
Related is a new arch interface ARCH_THREAD_STACK_OBJ_ALIGN()
which lets arches specifiy this. ARCH_STACK_PTR_ALIGN or a
power-of-two ceiling is used if not defined.
The default stack macros now use this instead of hard-coding
ARCH_STACK_PTR_ALIGN.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This operation is formally defined as rounding down a potential
stack pointer value to meet CPU and ABI requirments.
This was previously defined ad-hoc as STACK_ROUND_DOWN().
A new architecture constant ARCH_STACK_PTR_ALIGN is added.
Z_STACK_PTR_ALIGN() is defined in terms of it. This used to
be inconsistently specified as STACK_ALIGN or STACK_PTR_ALIGN;
in the latter case, STACK_ALIGN meant something else, typically
a required alignment for the base of a stack buffer.
STACK_ROUND_UP() only used in practice by Risc-V, delete
elsewhere.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
