From mboxrd@z Thu Jan 1 00:00:00 1970 From: Randolph Chung Subject: [parisc-linux] Re: syscall restart block. Date: Sun, 12 Sep 2004 17:05:11 -0700 Message-ID: <20040913000511.GU28659@tausq.org> References: <20040912184553.GT1854@baldric.uwo.ca> Reply-To: Randolph Chung Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: James Bottomley , parisc-linux@lists.parisc-linux.org To: Carlos O'Donell Return-Path: In-Reply-To: <20040912184553.GT1854@baldric.uwo.ca> List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: parisc-linux-bounces@lists.parisc-linux.org > If we move stack trampolines to the gateway pagethen signals can't be > delivered to the returning process during the trampoline walk (signals > are not allowed to be delivered for processes on the gateway page). So > it fixes our hole too. > > It also allows us to interpret PT_GNU_STACK properly, since the kernel > no longer needs to execute a trampoline on the users stack. The > toolchain can now correctly mark the stack as non-exec. > > I only just realized we still had this hole and it might manifest itself > under heavy signal load. i think the analysis is correct, but i don't like the solution! :-) various pieces of software (gcc, gdb) need to be able to read and analyze the signal trampoline for unwinding. putting the trampoline onto the gateway page will break these applications, because the gateway page is not readable by the user. randolph -- Randolph Chung Debian GNU/Linux Developer, hppa/ia64 ports http://www.tausq.org/ _______________________________________________ parisc-linux mailing list parisc-linux@lists.parisc-linux.org http://lists.parisc-linux.org/mailman/listinfo/parisc-linux