During boot, we detect whether or not all CPUs are brought up in the
same mode and signal this to the kernel using the N bit in the SPSR.
This patch tidies up the checking code to use the PSR_N_BIT macro,
rather than hardcoding the bit field and commenting it as such.
Signed-off-by: Will Deacon <will.deacon@arm.com>
In order to easily detect pathological cases, print some diagnostics
when the kernel boots.
This also provides helpers to detect that HYP mode is actually available,
which can be used by other subsystems to enable HYP specific features.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This patch does two things:
* Ensure that asynchronous aborts are masked at kernel entry.
The bootloader should be masking these anyway, but this reduces
the damage window just in case it doesn't.
* Enter svc mode via exception return to ensure that CPU state is
properly serialised. This does not matter when switching from
an ordinary privileged mode ("PL1" modes in ARMv7-AR rev C
parlance), but it potentially does matter when switching from a
another privileged mode such as hyp mode.
This should allow the kernel to boot safely either from svc mode or
hyp mode, even if no support for use of the ARM Virtualization
Extensions is built into the kernel.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
