Enabling various thread options causes failures on cortex-M0 boards

[nashif]

Adding the following options to hello_world:

diff --git a/samples/hello_world/prj.conf b/samples/hello_world/prj.conf
index 240d0959a5..70614d9ed7 100644
--- a/samples/hello_world/prj.conf
+++ b/samples/hello_world/prj.conf
@@ -1,2 +1,5 @@
 # nothing here
 CONFIG_SCHED_MULTIQ=y
+CONFIG_THREAD_STACK_INFO=y
+CONFIG_THREAD_MONITOR=y
+CONFIG_THREAD_CUSTOM_DATA=y

causes build failure:

s/kernel.dir/idle.c.obj   -c /home/nashif/Work/github/zephyr/kernel/idle.c
/home/nashif/Work/github/zephyr/arch/arm/core/swap_helper.S: Assembler messages:
/home/nashif/Work/github/zephyr/arch/arm/core/swap_helper.S:129: Error: invalid offset, value too big (0x00000080)
/home/nashif/Work/github/zephyr/arch/arm/core/swap_helper.S:131: Error: invalid offset, value too big (0x00000080)

[nashif]

bisect info:

2dd91eca0e25e35ab00567461ff4f3d773db24db is the first bad commit
commit 2dd91eca0e25e35ab00567461ff4f3d773db24db
Author: Andrew Boie <andrew.p.boie@intel.com>
Date:   Wed Jun 6 08:45:01 2018 -0700

    kernel: move thread monitor init to common code

    The original implementation of CONFIG_THREAD_MONITOR would
    try to leverage a thread's initial stack layout to provide
    the entry function with arguments for any given thread.

    This is problematic:

    - Some arches do not have a initial stack layout suitable for
    this
    - Some arches never enabled this at all (riscv32, nios2)
    - Some arches did not enable this properly
    - Dropping to user mode would erase or provide incorrect
    information.

    Just spend a few extra bytes to store this stuff directly
    in the k_thread struct and get rid of all the arch-specific
    code for this.

    Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

[andrewboie]

The problem here is that on Cortex M0, the LDR/STR assembly instructions have a maximium of offset of 0x7c:

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0497a/BABJGHFJ.html

In this configuration, the size of struct k_thread becomes large enough that the offset of thread->arch.basepri is 0x80:

     /* Restore previous interrupt disable state (irq_lock key) */
    ldr r0, [r2, #_thread_offset_to_basepri]
    movs.n r3, #0
    str r3, [r2, #_thread_offset_to_basepri]