When we register a TSB with the hypervisor, so that it or hardware can
handle TLB misses and do the TSB walk for us, the hypervisor traps
down to these trap when it incurs a TSB miss.

Processing is simple, we load the missing virtual address and context,
and do a full page table walk.
Signed-off-by: David S. Miller <davem@davemloft.net>

For 'tlb_type'.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

We look for "SUNW,sun4v" in the 'compatible' property
of the root OBP device tree node.

Protect every %ver register access, to make sure it is
not touched on sun4v, as %ver is hyperprivileged there.

Lock kernel TLB entries using hypervisor calls instead of
calls into OBP.
Signed-off-by: David S. Miller <davem@davemloft.net>

Technically the hypervisor call supports sending in a list
of all cpus to get the cross-call, but I only pass in one
cpu at a time for now.

The multi-cpu support is there, just ifdef'd out so it's easy to
enable or delete it later.
Signed-off-by: David S. Miller <davem@davemloft.net>

Sun4v has 4 interrupt queues: cpu, device, resumable errors,
and non-resumable errors.  A set of head/tail offset pointers
help maintain a work queue in physical memory.  The entries
are 64-bytes in size.

Each queue is allocated then registered with the hypervisor
as we bring cpus up.

The two error queues each get a kernel side buffer that we
use to quickly empty the main interrupt queue before we
call up to C code to log the event and possibly take evasive
action.
Signed-off-by: David S. Miller <davem@davemloft.net>

Needs to occur before we enable PSTATE_IE in %pstate.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Also, correct TRAP_PER_CPU_FAULT_INFO define, it should be
0x40 not 0x20.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

sun4v uses ASI_MMU instead of ASI_DMMU
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

For the expansion of __GET_CPUID() on SMP.
Signed-off-by: David S. Miller <davem@davemloft.net>

Happily we have no D-cache aliasing issues on these
chips, so the implementation is very straightforward.

Add a stub in bootup which will be where the patching
calls will be made for niagara/sun4v/hypervisor.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Things are a little tricky because, unlike sun4u, we have
to:

1) do a hypervisor trap to do the TLB load.
2) do the TSB lookup calculations by hand
Signed-off-by: David S. Miller <davem@davemloft.net>

V9 requires a write memory barrier before the instruction flush.
Signed-off-by: David S. Miller <davem@davemloft.net>

If we're just switching between different alternate global
sets, nop it out on sun4v.  Also, get rid of all of the
alternate global save/restore in the OBP CIF trampoline code.
Signed-off-by: David S. Miller <davem@davemloft.net>

They are totally unnecessary because:

1) Interrupts are already disabled when switch_to()
   runs.

2) We don't use hard-coded alternate globals any longer.

This found a case in rtrap, which still assumed alternate
global %g6 was current_thread_info(), and that is fixed
by this changeset as well.
Signed-off-by: David S. Miller <davem@davemloft.net>

Instead of setting/clearing PSTATE_AG we have to change
the %gl register value on sun4v.
Signed-off-by: David S. Miller <davem@davemloft.net>

As we save trap state onto the stack, the store buffer fills up
mid-way through and we stall for several cycles as the store buffer
trickles out to the L2 cache.  Meanwhile we can do some privileged
register reads and other calculations, essentially for free.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

And more consistently check cheetah{,_plus} instead
of assuming anything not spitfire is cheetah{,_plus}.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

When saving and restoing trap state, do the window spill/fill
handling inline so that we never trap deeper than 2 trap levels.
This is important for chips like Niagara.

The window fixup code is massively simplified, and many more
improvements are now possible.
Signed-off-by: David S. Miller <davem@davemloft.net>

This, as well as making the code cleaner, allows a simplification in
the TSB miss handling path.
Signed-off-by: David S. Miller <davem@davemloft.net>

On uniprocessor, it's always zero for optimize that.

On SMP, the jmpl to the stub kills the return address stack in the cpu
branch prediction logic, so expand the code sequence inline and use a
code patching section to fix things up.  This also always better and
explicit register selection, which will be taken advantage of in a
future changeset.

The hard_smp_processor_id() function is big, so do not inline it.

Fix up tests for Jalapeno to also test for Serrano chips too.  These
tests want "jbus Ultra-IIIi" cases to match, so that is what we should
test for.
Signed-off-by: David S. Miller <davem@davemloft.net>

There are several tricky races involved with growing the TSB.  So just
use base-size TSBs for user contexts and we can revisit enabling this
later.

One part of the SMP problems is that tsb_context_switch() can see
partially updated TSB configuration state if tsb_grow() is running in
parallel.  That's easily solved with a seqlock taken as a writer by
tsb_grow() and taken as a reader to capture all the TSB config state
in tsb_context_switch().

Then there is flush_tsb_user() running in parallel with a tsb_grow().
In theory we could take the seqlock as a reader there too, and just
resample the TSB pointer and reflush but that looks really ugly.

Lastly, I believe there is a case with threads that results in a TSB
entry lock bit being set spuriously which will cause the next access
to that TSB entry to wedge the cpu (since the TSB entry lock bit will
never clear).  It's either copy_tsb() or some bug elsewhere in the TSB
assembly.
Signed-off-by: David S. Miller <davem@davemloft.net>

The are distrupting, which by the sparc v9 definition means they
can only occur when interrupts are enabled in the %pstate register.
This never occurs in any of the trap handling code running at
trap levels > 0.

So just mark it as an unexpected trap.

This allows us to kill off the cee_stuff member of struct thread_info.
Signed-off-by: David S. Miller <davem@davemloft.net>

This way we don't need to lock the TSB into the TLB.
The trick is that every TSB load/store is registered into
a special instruction patch section.  The default uses
virtual addresses, and the patch instructions use physical
address load/stores.

We can't do this on all chips because only cheetah+ and later
have the physical variant of the atomic quad load.
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: David S. Miller <davem@davemloft.net>

If we are returning back to kernel mode, %g4 could be live
(for example, in the case where we window spill in the etrap
code).  So do not change it's value if going back to kernel.
Signed-off-by: David S. Miller <davem@davemloft.net>