Hi All,

In _stack_init function of crt0.S file, when the current mode is not user mode,
all the processor modes are parsed and the corresponding stack limit are set for
these modes for all A-profile and R-profile CPU's. But when the current processor
mode is hypervisor mode, changing to any other mode using CPSR will result in an
illegal instruction as per Arm-arm and simulator throws undefined instruction
exception.
This patch prevent the change of hypervisor mode to any other mode in _stack_init
function in crt0.S files.

Regression tested on arm-none-eabi target for newlib and newlib-nano and found
no regressions.

Ok for newlib master?

Regards,
Srinath.

libgloss/ChangeLog:

2023-02-23  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

         * arm/crt0.S (_stack_init): Add check for hypervisor mode.

newlib/ChangeLog:

2023-02-23  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

         * libc/sys/arm/crt0.S (_stack_init): Add check for hypervisor mode.