Date: Tue, 1 Feb 2005 06:43:45 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Maxim Sobolev <sobomax@portaone.com> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/linux linux_sysvec.c src/sys/alpha/osf1 imgact_osf1.c osf1_sysvec.c src/sys/amd64/linux32 linux32_sysvec.c src/sys/compat/ia32 ia32_sysvec.c src/sys/compat/pecoff imgact_pecoff.c src/sys/compat/svr4 imgact_svr4.c svr4_sysvec.c ... Message-ID: <200502010643.45784.jhb@FreeBSD.org> In-Reply-To: <41FEBAE5.7010201@portaone.com> References: <200501292312.j0TNC0VE052634@repoman.freebsd.org> <200501311441.24275.jhb@FreeBSD.org> <41FEBAE5.7010201@portaone.com>
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On Monday 31 January 2005 06:10 pm, Maxim Sobolev wrote: > John Baldwin wrote: > > On Saturday 29 January 2005 06:12 pm, Maxim Sobolev wrote: > >>sobomax 2005-01-29 23:12:00 UTC > >> > >> FreeBSD src repository > >> > >> Modified files: > >> sys/alpha/linux linux_sysvec.c > >> sys/alpha/osf1 imgact_osf1.c osf1_sysvec.c > >> sys/amd64/linux32 linux32_sysvec.c > >> sys/compat/ia32 ia32_sysvec.c > >> sys/compat/pecoff imgact_pecoff.c > >> sys/compat/svr4 imgact_svr4.c svr4_sysvec.c > >> sys/i386/ibcs2 ibcs2_sysvec.c imgact_coff.c > >> sys/i386/linux imgact_linux.c linux_sysvec.c > >> linux_machdep.c > >> sys/kern imgact_aout.c imgact_elf.c imgact_gzip.c > >> imgact_shell.c kern_exec.c kern_kse.c > >> sys/modules Makefile > >> sys/sys imgact.h syscallsubr.h > >> Log: > >> o Split out kernel part of execve(2) syscall into two parts: one that > >> copies arguments into the kernel space and one that operates > >> completely in the kernel space; > >> > >> o use kernel-only version of execve(2) to kill another stackgap in > >> linuxlator/i386. > >> > >> Obtained from: DragonFlyBSD (partially) > >> MFC after: 2 weeks > > > > Cool, this had been on my anti-stackgap todo list as well. > > > :-) > > We have been tolerating this stackgap hack for too long. > > Right now linuxlator/i386 is almost stackgap-free. The only remaining > stackgap is in semctl(2) syscal, which in my opinion it is very > over/under engineered API, so that there is no a good clean way to do > the split. At the same time, it's not the one used oftenly, so that I > can wait when I (or somebody else) is in the right mood to do the > remaining work. > > Other arches/emulation layers are awaiting for somebody (maintainers?) > to do the work, which will be very easy one, since most popular kernel > interfaces that work on userland structures/buffers have been split. That's not the only one. All the filesystem system calls use the stackgap to handle the /compat/linux namespace. Fixing that will not be trivial, as it will involve teaching namei() to retrieve filenames using a uio or some such so that names can either be in user space or in kernel space. Either that or we add native support for prefixes like /compat/foo to namei() by sticking a pointer to a prefix in struct sysent or some such. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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