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Re: Stack bias
On Tue, Aug 11, 2009 at 01:21:22PM -0400, der Mouse wrote:
> Okay, here is part of the confusion. To me, a leaf routine is one that
> does not call any others; depending on factors such as the complexity
> of the routine and the smartness of the compiler, this may or may not
> get compiled to code using save and restore.
> I was actually talking about routines that _do_ save on entry and
> restore on exit, but which have no desire to refer to %sp. But, based
> on what you say here, this is not safe because the kernel may want to
> spill user windows onto the stack, and will assume %o6/%sp indicates
> where to put them. Have I finally got myself straightened out?
'save' is a subtract instruction that reads from the old window
and writes to the new. It is always(?) used to subtract from %sp
and thus writes to the new %o6.
For sparc(64) a leaf routine is specifically one that doesn't
David Laight: david%l8s.co.uk@localhost
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