Linux does not gracefully deal with multiple processors going
through OS_MCA aa part of the same MCA event.  The first cpu
into OS_MCA grabs the ia64_mca_serialize lock.  Subsequent
cpus wait for that lock, preventing them from reporting in as
rendezvoused.  The first cpu waits 5 seconds then complains
that all the cpus have not rendezvoused.  The first cpu then
handles its MCA and frees up all the rendezvoused cpus and
releases the ia64_mca_serialize lock.  One of the subsequent
cpus going thought OS_MCA then gets the ia64_mca_serialize
lock, waits another 5 seconds and then complains that none of
the other cpus have rendezvoused.

This patch allows multiple CPUs to gracefully go through OS_MCA.

The first CPU into ia64_mca_handler() grabs a mca_count lock.
Subsequent CPUs into ia64_mca_handler() are added to a list of cpus
that need to go through OS_MCA (a bit set in mca_cpu), and report
in as rendezvoused, and but spin waiting their turn.

The first CPU sees everyone rendezvous, handles his MCA, wakes up
one of the other CPUs waiting to process their MCA (by clearing
one mca_cpu bit), and then waits for the other cpus to complete
their MCA handling.  The next CPU handles his MCA and the process
repeats until all the CPUs have handled their MCA.  When the last
CPU has handled it's MCA, it sets monarch_cpu to -1, releasing all
the CPUs.

In testing this works more reliably and faster.

Thanks to Keith Owens for suggesting numerous improvements
to this code.
Signed-off-by: NRuss Anderson <rja@sgi.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

* Kexec adds some code to arch/ia64/kernel/smp.c which needs ia64_mca_pal_base,
  so the kexec patch (actually the kdump patch) declares this
  per-cpu variable in include/asm-ia64/kexec.h.

* ia64_mca_pal_base is defined in arch/ia64/kernel/mca.c, so it
  seems to me that it would make a lot more sense to declare it in
  include/asm-ia64/mca.h.
Signed-off-by: NSimon Horman <horms@verge.net.au>
Signed-off-by: NTony Luck <tony.luck@intel.com>

struct ia64_sal_os_state has three semi-independent sections.  The code
in mca_asm.S assumes that these three sections are contiguous, which
makes it very awkward to add new data to this structure.  Remove the
assumption that the sections are contiguous.  Define a macro to shorten
references to offsets in ia64_sal_os_state.

This patch does not change the way that the code behaves.  It just
makes it easier to update the code in future and to add fields to
ia64_sal_os_state when debugging the MCA/INIT handlers.
Signed-off-by: NKeith Owens <kaos@sgi.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

The MCA/INIT handlers maintain important state in the SAL to OS (sos)
area and in the monarch_cpu flag.  Kernel debuggers (such as KDB) need
this data, and may need to adjust the monarch_cpu field so make the
data available to the notify_die hooks.  Define two more events for
calling the functions on the notify_die chain.
Signed-off-by: NKeith Owens <kaos@sgi.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

here is the BSP removal support for IA64. Its pretty much the same thing that
was released a while back, but has your feedback incorporated.

- Removed CONFIG_BSP_REMOVE_WORKAROUND and associated cmdline param
- Fixed compile issue with sn2/zx1 due to a undefined fix_b0_for_bsp
- some formatting nits (whitespace etc)

This has been tested on tiger and long back by alex on hp systems as well.
Signed-off-by: NAshok Raj <ashok.raj@intel.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Wire the MCA/INIT handler stacks into DTR[2] and track them in
IA64_KR(CURRENT_STACK).  This gives the MCA/INIT handler stacks the
same TLB status as normal kernel stacks.  Reload the old CURRENT_STACK
data on return from OS to SAL.
Signed-off-by: NKeith Owens <kaos@sgi.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

The bulk of the change.  Use per cpu MCA/INIT stacks.  Change the SAL
to OS state (sos) to be per process.  Do all the assembler work on the
MCA/INIT stacks, leaving the original stack alone.  Pass per cpu state
data to the C handlers for MCA and INIT, which also means changing the
mca_drv interfaces slightly.  Lots of verification on whether the
original stack is usable before converting it to a sleeping process.
Signed-off-by: NKeith Owens <kaos@sgi.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!