Date: Wed, 18 Apr 2001 12:27:28 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Doug Rabson <dfr@nlsystems.com> Cc: cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha exception.s Message-ID: <XFMail.010418122728.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.33.0104182012240.55816-100000@salmon.nlsystems.com>
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On 18-Apr-01 Doug Rabson wrote: > On Wed, 18 Apr 2001, John Baldwin wrote: > >> jhb 2001/04/18 10:17:55 PDT >> >> Modified files: >> sys/alpha/alpha exception.s >> Log: >> Back out the previous revision as it causes random sig 11's to userland >> processes until a better fix is found. > > I can see several possible races here. For instance, if an interrupt > happened partway through restoring registers trying to return to userland, > we could corrupt the user's t7 pretty easily. > > I can't quite think of the correct solution yet though. Oh, we share the same stack frame for user and kernel returns? Oh yuck. I can hack around that by raising the IPL in Lkernelret before changing t7, but if we use the same stackframe how do interrupts in the kernel work at all w/o trashing the user frame? -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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