We've seen several bugs caused by interrupt weirdness in the kdump kernel.
Panicking from an interrupt handler means we fail to EOI the interrupt, and
so the second kernel never gets that interrupt ever again. We also see hangs
on JS20 where we take interrupts in the second kernel early during boot.

This patch fixes both those problems, and although it adds more code to the
crash path I think it is the best solution.
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The panic CPU is waiting forever due to some large timeout value if some
CPU is not responding to an IPI.
This patch fixes the problem - the maximum waiting period will be
10 seconds and then the kdump boot will go ahead.
Signed-off-by: NHaren Myneni <haren@us.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

- This contains the arch specific changes for the following the
kdump generic fixes which were already accepted in the upstream.
       .   Capturing CPU registers (for the case of 'panic' and invoking
the dump using 'sysrq-trigger') from a function (stack frame) which will
be not be available during the kdump boot. Hence, might result in
invalid stack trace.
       .   Dynamically allocating per cpu ELF notes section instead of
statically for NR_CPUS.

- Fix the compiler warning in prom_init.c.
Signed-off-by: NHaren Myneni <haren@us.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This patch fixes the compilation error (shown below) when CONFIG_SMP=n.
    arch/powerpc/kernel/crash.c: In function `crash_kexec_prepare_cpus':
    arch/powerpc/kernel/crash.c:236: error: implicit declaration of
    function `smp_release_cpus'
Signed-off-by: NHaren Myneni <haren@us.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Implementing the machine_crash_shutdown which will be called by
crash_kexec (called in case of a panic, sysrq etc.). Disable the
interrupts, shootdown cpus using debugger IPI and collect regs
for all CPUs.

elfcorehdr= specifies the location of elf core header stored by
the crashed kernel. This command line option will be passed by
the kexec-tools to capture kernel.

savemaxmem= specifies the actual memory size that the first kernel
has and this value will be used for dumping in the capture kernel.
This command line option will be passed by the kexec-tools to
capture kernel.
Signed-off-by: NHaren Myneni <haren@us.ibm.com>
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>