Date: Fri, 23 May 2003 16:16:43 -0700 (PDT) From: Marcel Moolenaar <marcel@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/ia64/ia64 context.s Message-ID: <200305232316.h4NNGhpc096192@repoman.freebsd.org>
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marcel 2003/05/23 16:16:43 PDT
FreeBSD src repository
Modified files:
sys/ia64/ia64 context.s
Log:
In swapctx(), put the RSE in enforced lazy mode before we flush the
register stack. There's nothing really wrong with flushing before
putting the RSE in enforced lazy mode, provided you don't depend on
ar.bspstore being equal to ar.bsp when the RSE has been put in
enforced lazy more. The small window between the flush and setting
the RSE may be sufficient to have the RSE eagerly increase the dirty
region (and hence cause ar.bspstore != ar.bsp) or have an interrupt
that may even get the laziest RSE to do something.
Anyway: we don't depend on ar.bspstore being equal to ar.bsp, so
nothing was and is broken. But the code was non-intuitive and
easily confuses. This is a source of future bugs.
Note: the advantage of not depending on ar.bspstore is that there's
some recilience against an interrupted flushrs. Clobbering is limited
to stacked register contents only, not to RSE address clobbering.
Approved: re@ (blanket)
Revision Changes Path
1.2 +2 -2 src/sys/ia64/ia64/context.s
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