Commit Graph

5 Commits

Author SHA1 Message Date
Takao Indoh 9ee27c7639 [IA64] Save I-resources to ia64_sal_os_state
This is a patch related to this discussion.
http://www.spinics.net/lists/linux-ia64/msg07605.html

When INIT is sent, ip/psr/pfs register is stored to the I-resources
(iip/ipsr/ifs registers), and they are copied in the min-state save
area(pmsa_{iip,ipsr,ifs}).

Therefore, in creating pt_regs at ia64_mca_modify_original_stack(),
cr_{iip,ipsr,ifs} should be derived from pmsa_{iip,ipsr,ifs}. But
current code copies pmsa_{xip,xpsr,xfs} to cr_{iip,ipsr,ifs}
when PSR.ic is 0.

finish_pt_regs(struct pt_regs *regs, const pal_min_state_area_t *ms,
                unsigned long *nat)
{
(snip)
        if (ia64_psr(regs)->ic) {
                regs->cr_iip = ms->pmsa_iip;
                regs->cr_ipsr = ms->pmsa_ipsr;
                regs->cr_ifs = ms->pmsa_ifs;
        } else {
                regs->cr_iip = ms->pmsa_xip;
                regs->cr_ipsr = ms->pmsa_xpsr;
                regs->cr_ifs = ms->pmsa_xfs;
        }

It's ok when PSR.ic is not 0. But when PSR.ic is 0, this could be
a problem when we investigate kernel as the value of regs->cr_iip does
not point to where INIT really interrupted.

At first I tried to change finish_pt_regs() so that it uses always
pmsa_{iip,ipsr,ifs} for cr_{iip,ipsr,ifs}, but Keith Owens pointed out
it could cause another problem if I change it.

>The only problem I can think of is an MCA/INIT
>arriving while code like SAVE_MIN or SAVE_REST is executing.  Back
>tracing at that point using pmsa_iip is going to be a problem, you have
>no idea what state the registers or stack are in.

I confirmed he was right, so I decided to keep it as-is and to
save pmsa_{iip,ipsr,ifs} to ia64_sal_os_state for debugging.

An attached patch is just adding new members into ia64_sal_os_state to
save pmsa_{iip,ipsr,ifs}.

Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2009-12-14 16:37:58 -08:00
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
Hidetoshi Seto 4295ab3488 [IA64] kdump: Mask MCA/INIT on frozen cpus
Summary:

  INIT asserted on kdump kernel invokes INIT handler not only on a
  cpu that running on the kdump kernel, but also BSP of the panicked
  kernel, because the (badly) frozen BSP can be thawed by INIT.

Description:

  The kdump_cpu_freeze() is called on cpus except one that initiates
  panic and/or kdump, to stop/offline the cpu (on ia64, it means we
  pass control of cpus to SAL, or put them in spinloop).  Note that
  CPU0(BSP) always go to spinloop, so if panic was happened on an AP,
  there are at least 2cpus (= the AP and BSP) which not back to SAL.

  On the spinning cpus, interrupts are disabled (rsm psr.i), but INIT
  is still interruptible because psr.mc for mask them is not set unless
  kdump_cpu_freeze() is not called from MCA/INIT context.

  Therefore, assume that a panic was happened on an AP, kdump was
  invoked, new INIT handlers for kdump kernel was registered and then
  an INIT is asserted.  From the viewpoint of SAL, there are 2 online
  cpus, so INIT will be delivered to both of them.  It likely means
  that not only the AP (= a cpu executing kdump) enters INIT handler
  which is newly registered, but also BSP (= another cpu spinning in
  panicked kernel) enters the same INIT handler.  Of course setting of
  registers in BSP are still old (for panicked kernel), so what happen
  with running handler with wrong setting will be extremely unexpected.
  I believe this is not desirable behavior.

How to Reproduce:

  Start kdump on one of APs (e.g. cpu1)
    # taskset 0x2 echo c > /proc/sysrq-trigger
  Then assert INIT after kdump kernel is booted, after new INIT handler
  for kdump kernel is registered.

Expected results:

  An INIT handler is invoked only on the AP.

Actual results:

  An INIT handler is invoked on the AP and BSP.

Sample of results:

  I got following console log by asserting INIT after prompt "root:/>".
  It seems that two monarchs appeared by one INIT, and one panicked at
  last.  And it also seems that the panicked one supposed there were
  4 online cpus and no one did rendezvous:

    :
    [  0 %]dropping to initramfs shell
    exiting this shell will reboot your system
    root:/> Entered OS INIT handler. PSP=fff301a0 cpu=0 monarch=0
    ia64_init_handler: Promoting cpu 0 to monarch.
    Delaying for 5 seconds...
    All OS INIT slaves have reached rendezvous
    Processes interrupted by INIT - 0 (cpu 0 task 0xa000000100af0000)
    :
    <<snip>>
    :
    Entered OS INIT handler. PSP=fff301a0 cpu=0 monarch=1
    Delaying for 5 seconds...
    mlogbuf_finish: printing switched to urgent mode, MCA/INIT might be dodgy or fail.
    OS INIT slave did not rendezvous on cpu 1 2 3
    INIT swapper 0[0]: bugcheck! 0 [1]
    :
    <<snip>>
    :
    Kernel panic - not syncing: Attempted to kill the idle task!

Proposed fix:

  To avoid this problem, this patch inserts ia64_set_psr_mc() to mask
  INIT on cpus going to be frozen.  This masking have no effect if the
  kdump_cpu_freeze() is called from INIT handler when kdump_on_init == 1,
  because psr.mc is already turned on to 1 before entering OS_INIT.
  I confirmed that weird log like above are disappeared after applying
  this patch.

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 16:17:05 -07:00
Matthew Wilcox e088a4ad7f [IA64] Convert ia64 to use int-ll64.h
It is generally agreed that it would be beneficial for u64 to be an
unsigned long long on all architectures.  ia64 (in common with several
other 64-bit architectures) currently uses unsigned long.  Migrating
piecemeal is too painful; this giant patch fixes all compilation warnings
and errors that come as a result of switching to use int-ll64.h.

Note that userspace will still see __u64 defined as unsigned long.  This
is important as it affects C++ name mangling.

[Updated by Tony Luck to change efi.h:efi_freemem_callback_t to use
 u64 for start/end rather than unsigned long]

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2009-06-17 09:33:49 -07:00
Tony Luck 7f30491ccd [IA64] Move include/asm-ia64 to arch/ia64/include/asm
After moving the the include files there were a few clean-ups:

1) Some files used #include <asm-ia64/xyz.h>, changed to <asm/xyz.h>

2) Some comments alerted maintainers to look at various header files to
make matching updates if certain code were to be changed. Updated these
comments to use the new include paths.

3) Some header files mentioned their own names in initial comments. Just
deleted these self references.

Signed-off-by: Tony Luck <tony.luck@intel.com>
2008-08-01 10:21:21 -07:00