tree af71342b28547a4f9bb3611c1947a4330c544514
parent 84bd6d8b9c0f06b3f188efb479c77e20f05e9a8a
author David S. Miller <davem@davemloft.net> 1413688353 -0400
committer David S. Miller <davem@davemloft.net> 1413688353 -0400

sparc64: Do not define thread fpregs save area as zero-length array.

This breaks the stack end corruption detection facility.

What that facility does it write a magic value to "end_of_stack()"
and checking to see if it gets overwritten.

"end_of_stack()" is "task_thread_info(p) + 1", which for sparc64 is
the beginning of the FPU register save area.

So once the user uses the FPU, the magic value is overwritten and the
debug checks trigger.

Fix this by making the size explicit.

Due to the size we use for the fpsaved[], gsr[], and xfsr[] arrays we
are limited to 7 levels of FPU state saves.  So each FPU register set
is 256 bytes, allocate 256 * 7 for the fpregs area.

Reported-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>