o Move all files from sparc64/kernel/ to sparc/kernel
  - rename as appropriate
o Update sparc/Makefile to the changes
o Update sparc/kernel/Makefile to include the sparc64 files

NOTE: This commit changes link order on sparc64!

Link order had to change for either of sparc32 and sparc64.
And assuming sparc64 see more testing than sparc32 change link
order on sparc64 where issues will be caught faster.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

And this allows us to indicate HAVE_LATENCYTOP_SUPPORT.

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

Things like lockdep can try to do stack backtraces before
the irqstack blocks have been setup.  So don't try to match
their ranges so early on.

Also, remove unused variable in save_stack_trace().

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

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

Bug reported by Alexander Beregalov.

Before we dereference the stack frame or try to peek at the
pt_regs magic value, make sure the entire object is within
the kernel stack bounds.

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

Today's linux-next build (spac64 allmodconfig) failed like this:

arch/sparc64/kernel/stacktrace.c:50: warning: type defaults to `int' in declaration of `EXPORT_SYMBOL_GPL'
arch/sparc64/kernel/stacktrace.c:50: warning: parameter names (without types) in function declaration
arch/sparc64/kernel/stacktrace.c:50: warning: data definition has no type or storage class

Signed-off-by: Stephen Rothwell <sf@canb.auug.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Andrew Morton reported this against linux-next:

ERROR: ".save_stack_trace" [tests/backtracetest.ko] undefined!

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The offset to the pt_regs area was wrong, so we weren't
looking at the right location for the magic cookie.

A trap frame is composed of a "struct sparc_stackf" then
a "struct pt_regs", the code was using "struct reg_window"
instead of "struct sparc_stackf".

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

Now that we have a magic cookie in the pt_regs, we can
properly detect trap frames in stack bactraces.

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

Doing a 'flushw' every stack trace capture creates so much overhead
that it makes lockdep next to unusable.

We only care about the frame pointer chain and the function caller
program counters, so flush those by hand to the stack frame.

This is significantly more efficient than a 'flushw' because:

1) We only save 16 bytes per active register window to the stack.

2) This doesn't push the entire register window context of the current
   call chain out of the cpu, forcing register window fill traps as we
   return back down.

Note that we can't use 'restore' and 'save' instructions to move
around the register windows because that wouldn't work on Niagara
processors.  They optimize 'save' into a new register window by
simply clearing out the registers instead of pulling them in from
the on-chip register window backing store.

Based upon a report by Tom Callaway.

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