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 ...
John Baldwin
jhb at FreeBSD.org
Tue Feb 1 10:13:31 PST 2005
On Tuesday 01 February 2005 10:26 am, Maxim Sobolev wrote:
> John Baldwin wrote:
> > 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.
>
> Hmm, are you 100% sure? As long as I can see they all use LCONVPATH()
> macros, which in turn uses linux_emul_convpath() function from
> linux_util.c. The latter function is stackgap-free. The only
> commonly-used function "infected" with stackgap in linuxlator is
> linux_emul_find (and so that CHECKALT*() macroses that use it). My plan
> was to remove that function entirely, but apparently it is still used in
> non-i386 versions of linuxlator, so that it can be done yet.
Ah, someone fixed this already while I wasn't looking. Now we should just
genericize linux_emul_convpath() (to take a prefix argument) and fix all the
ABIs to use that instead. I can add that to my todo list I guess. There are
also other stackgap uses in other ABIs that need to be worked on besides just
Linux/i386, but those are already on my todo.
--
John Baldwin <jhb at FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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