From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailserv2.iuinc.com (qmailr@mailserv2.iuinc.com [206.245.164.55]) by puffin.external.hp.com (8.8.7/8.8.7) with SMTP id KAA03850 for ; Mon, 2 Aug 1999 10:50:00 -0600 From: Jerry Huck Message-Id: <199908021650.JAA10088@lucy.cup.hp.com> Subject: Re: [parisc-linux] HPUX syscall ABI? To: Matthew.Wilcox@genedata.com Date: Mon, 2 Aug 1999 09:50:39 -0700 (PDT) Cc: lamont@security.hp.com, parisc-linux@thepuffingroup.com In-Reply-To: <19990802082612.X25925@mencheca.ch.genedata.com> from Matthew Wilcox at Aug "2," 1999 "08:26:12" am MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-ID: > Date: Mon, 2 Aug 1999 08:26:12 +0200 > From: Matthew Wilcox > To: LaMont Jones > Cc: Matthew Wilcox , > parisc-linux@thepuffingroup.com > Subject: Re: [parisc-linux] HPUX syscall ABI? ... To LaMont's reply Matthew writes: > Yep, that's exactly what I need. Urgh, so I have to grab the arguments > off the user-mode stack before switching to the kernel-mode stack.. Just as an aside, you might want to use the gateway page to do some fix-ups. On the gateway page, you can delay the promotion, do some argument shuffling and other glue code in the user's context, and then finally gateway to priv 0 (and presumably to some kernel code). You could load up all the scratch registers with arguments and then have the kernel-stack switch code push the arguments after the priv change. I've always wanted HP-UX to use this type of approach to read as many arguments (and memory data structures) as can fit in the scratch region on both call and return. You can avoid all the high overhead kernel-user copy code. Simple things, like "gettimeofday", could pop into the kernel, get the return values, return to priv 3 near those gateway pages, write the return values to memory, and return to the caller without any kernel-user copies. Jerry Huck (PA-RISC architecture group)