The register state struct is 848 bytes, which ends up bloating the
apple_rtkit_crashlog_dump_regs stack frame beyond 1024 on some
32-bit platforms, triggering compile warnings.

This doesn't matter for 64BIT/ARM64, but there's also no good reason to
copy the structure to the stack in this case. We can use __packed to
avoid alignment issues, there are no double-read hazards, and this is a
fatal error path so performance does not matter.

Fixes: 22991d8d5725 ("soc: apple: rtkit: Add register dump decoding to crashlog")
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

When the coprocessor crashes, it's useful to get a proper register dump
so we can find out what the firmware was doing. Add a decoder for this.

Originally this had ESR decoding by reusing the ARM64 arch header for
this, but that introduces some module linking and cross-arch compilation
issues, so let's leave that out for now.

Reviewed-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Signed-off-by: Hector Martin <marcan@marcan.st>

Apple SoCs such as the M1 come with multiple embedded co-processors
running proprietary firmware. Communication with those is established
over a simple mailbox using the RTKit IPC protocol.

This cannot be implemented inside the mailbox subsystem since on top
of communication over channels we also need support for starting,
hibernating and resetting these co-processors. We also need to
handle shared memory allocations differently depending on the
co-processor and don't want to split that across multiple drivers.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sven Peter <sven@svenpeter.dev>