Date: Fri, 1 Sep 2006 09:29:00 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: Peter Chubb <peterc@gelato.unsw.edu.au> Cc: marcel@FreeBSD.org, ppc@FreeBSD.org, ia64@FreeBSD.org Subject: Re: IA64, PPC system call path audit patches Message-ID: <20060901092636.E4921@fledge.watson.org> In-Reply-To: <87irk8at9i.wl%peterc@quokka.chubb.wattle.id.au> References: <20060901080402.W97485@fledge.watson.org> <87irk8at9i.wl%peterc@quokka.chubb.wattle.id.au>
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On Fri, 1 Sep 2006, Peter Chubb wrote: > You've only caught the IA64 slow path system call entries. The fast path is > highly optimised assembly language inside arch/ia64/kernel/fsys.S, that > avoids doing a trap at all. > > With a modern libc, syscall_via_break is only called for a very few system > calls. Hmm. I'm confused by the above comment -- I'm catching system calls on the kernel side of the system call invocation around the system call, not on the libc side. I only see two system call demux points in the src/sys/ia64 tree: ./ia32/ia32_trap.c: error = (*callp->sy_call)(td, args64); ./ia64/trap.c: error = (*callp->sy_call)(td, args); Both of which are covered in the patch I attached. I'm under the impression that the different mechanisms to enter the kernel system call path converge prior to the system call table evaluation, in the kernel trap code. Do I misunderstand? Robert N M Watson Computer Laboratory University of Cambridge
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