From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Thu, 06 May 2004 03:42:24 +0000 Subject: Re: 2.6.5 unwind problem with rp <- r0 Message-Id: <16537.46112.573022.514558@napali.hpl.hp.com> List-Id: References: <4885.1083211711@kao2.melbourne.sgi.com> In-Reply-To: <4885.1083211711@kao2.melbourne.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Thu, 06 May 2004 12:04:13 +1000, Keith Owens said: Keith> On Wed, 5 May 2004 17:19:37 -0700, David Mosberger Keith> wrote: >> I'd have preferred if there had been a simple and clean fix to >> the existing unwinder that supports .save rp,r0, but I haven't >> seen/found something acceptable yet. Keith> The clean patch is a bit bigger than the kludge. I considered that approach but rejected it because it runs the "FORTRAN constant" risk. That is, someone might write to a saved register (e.g., via unw_set_br()) and end up inadvertently redefining the 0 "constant" (unw_r0) to a non-zero value. Perhaps what we could do is change unw_access_{gr,br,fr,ar,pr} to reject attempts to write to the special save-address &unw_r0. I think that would make it safe. --david