The client manager (venus) blocks in sys_mount() before entering its
event loop answering requests from the kernel device (cfs). sys_mount()
calls VFS_STATFS() internally which caused an upcall through cfs,
which was never answered.
Now don't consider the fs fully mounted before the VFS_START() was
called at the vey end of sys_mount(). So VFS_STATFS() will return
an error which is ignored.
and the subsequent namei(): inform the kernel portion of
valid filenames and then disallow symlink lookups for
those filenames by means of a hook in namei().
with suggestions from provos@
also, add (currently unused) seqnr field to struct
systrace_replace, from provos@
and make the stack and heap non-executable by default. the changes
fall into two basic catagories:
- pmap and trap-handler changes. these are all MD:
= alpha: we already track per-page execute permission with the (software)
PG_EXEC bit, so just have the trap handler pay attention to it.
= i386: use a new GDT segment for %cs for processes that have no
executable mappings above a certain threshold (currently the
bottom of the stack). track per-page execute permission with
the last unused PTE bit.
= powerpc/ibm4xx: just use the hardware exec bit.
= powerpc/oea: we already track per-page exec bits, but the hardware only
implements non-exec mappings at the segment level. so track the
number of executable mappings in each segment and turn on the no-exec
segment bit iff the count is 0. adjust the trap handler to deal.
= sparc (sun4m): fix our use of the hardware protection bits.
fix the trap handler to recognize text faults.
= sparc64: split the existing unified TSB into data and instruction TSBs,
and only load TTEs into the appropriate TSB(s) for the permissions.
fix the trap handler to check for execute permission.
= not yet implemented: amd64, hppa, sh5
- changes in all the emulations that put a signal trampoline on the stack.
instead, we now put the trampoline into a uvm_aobj and map that into
the process separately.
originally from openbsd, adapted for netbsd by me.
