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linux/arch/ia64
Hidetoshi Seto 07a6a4ae82 [IA64] kexec: Make INIT safe while transition to
kdump/kexec kernel

Summary:

  Asserting INIT on the beginning of kdump/kexec kernel will result
  in unexpected behavior because INIT handler for previous kernel is
  invoked on new kernel.

Description:

  In panic situation, we can receive INIT while kernel transition,
  i.e. from beginning of panic to bootstrap of kdump kernel.
  Since we initialize registers on leave from current kernel, no
  longer monarch/slave handlers of current kernel in virtual mode are
  called safely.  (In fact system goes hang as far as I confirmed)

How to Reproduce:

  Start kdump
    # echo c > /proc/sysrq-trigger
  Then assert INIT while kdump kernel is booting, before new INIT
  handler for kdump kernel is registered.

Expected(Desirable) result:

  kdump kernel boots without any problem, crashdump retrieved

Actual result:

  INIT handler for previous kernel is invoked on kdump kernel
  => panic, hang etc. (unexpected)

Proposed fix:

  We can unregister these init handlers from SAL before jumping into
  new kernel, however then the INIT will fallback to default behavior,
  result in warmboot by SAL (according to the SAL specification) and
  we cannot retrieve the crashdump.

  Therefore this patch introduces a NOP init handler and register it
  to SAL before leave from current kernel, to start kdump safely by
  preventing INITs from entering virtual mode and resulting in warmboot.

  On the other hand, in case of kexec that not for kdump, it also
  has same problem with INIT while kernel transition.
  This patch handles this case differently, because for kexec
  unregistering handlers will be preferred than registering NOP
  handler, since the situation "no handlers registered" is usual
  state for kernel's entry.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Haren Myneni <hbabu@us.ibm.com>
Cc: kexec@lists.infradead.org
Acked-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2009-09-14 16:18:02 -07:00
..
configs sgi-gru: remove SGI_GRU as a valid config option for ia64 configs with SGI_UV 2009-04-02 19:05:07 -07:00
dig x86, ia64: convert to use generic dma_map_ops struct 2009-01-06 14:06:57 +01:00
hp Pull for-2.6.31 into release 2009-06-17 09:35:24 -07:00
ia32 generic compat_sys_ustat 2009-03-27 14:43:57 -04:00
include/asm [IA64] kexec: Make INIT safe while transition to 2009-09-14 16:18:02 -07:00
kernel [IA64] kexec: Make INIT safe while transition to 2009-09-14 16:18:02 -07:00
kvm KVM: ia64: fix build failures due to ia64/unsigned long mismatches 2009-08-05 15:04:16 +03:00
lib [IA64] fix csum_ipv6_magic() 2009-09-02 09:14:48 -07:00
mm Move FAULT_FLAG_xyz into handle_mm_fault() callers 2009-06-21 13:08:22 -07:00
oprofile oprofile: more whitespace fixes 2008-10-15 20:55:51 +02:00
pci ia64/PCI: adjust section annotation for pcibios_setup() 2009-06-30 16:26:53 -07:00
scripts ia64/pv_ops/pvchecker: support mov = ar.itc paravirtualization 2009-03-26 10:50:09 -07:00
sn [IA64] sprintf should not be used with same source & destination address 2009-06-30 14:02:00 -07:00
uv [IA64] Simplify SGI uv vs. sn2 driver issues 2008-11-04 11:29:39 -08:00
xen [IA64] remove obsolete irq_desc_t typedef 2009-06-15 14:34:31 -07:00
install.sh
Kconfig dma-mapping: ia64: add CONFIG_DMA_API_DEBUG support 2009-06-18 13:03:58 -07:00
Kconfig.debug
Makefile arch/ia64/Makefile: Remove -mtune=merced in IA64 kernel build 2009-08-11 14:52:11 -07:00
module.lds