Fix another bug: if argv[0] is NULL, garbadge args might be added for
shell script
Submitted by: Tor Egge <Tor.Egge@idi.ntnu.no> (with yet one fault detect from me)
difference of approx 3mins in make world on my P6!!! This means
that vfork now has full address space sharing, so beware with
sloppy vfork programming. Also, you really do need to apply
the previously committed popen fix in libc.
Zero the b_dirty{off,end} after cluster-comitting a group of buffers.
With these fixes, I was able to complete a 'make world' with remote src
and obj directories.
were always in a tss; that tss just changed from the one in the
pcb to common_tss (who knows where it was when there was no curpcb?).
Not using the pcb also fixed the problem that there is no pcb in
idle(), so we now always get useful register values.
cache queue more often. The pageout daemon had to be waken up
more often than necessary since pages were not put on the
cache queue, when they should have been.
Submitted by: David Greenman <dg@freebsd.org>
fork. (On my machine, fork is about 240usecs, vfork is 78usecs.)
Implement rfork(!RFPROC !RFMEM), which allows a thread to divorce its memory
from the other threads of a group.
Implement rfork(!RFPROC RFCFDG), which closes all file descriptors, eliminating
possible existing shares with other threads/processes.
Implement rfork(!RFPROC RFFDG), which divorces the file descriptors for a
thread from the rest of the group.
Fix the case where a thread does an exec. It is almost nonsense for a thread
to modify the other threads address space by an exec, so we
now automatically divorce the address space before modifying it.
longer has anything to do with vnodes and never had anything to do
with buffers, but it needs the definitions of B_READ and B_WRITE
for use with the bogus useracc() interface and was getting them
bogusly due to excessive cleanups in rev.1.49.
space. (!)
Have each process use the kernel stack and pcb in the kvm space. Since
the stacks are at a different address, we cannot copy the stack at fork()
and allow the child to return up through the function call tree to return
to user mode - create a new execution context and have the new process
begin executing from cpu_switch() and go to user mode directly.
In theory this should speed up fork a bit.
Context switch the tss_esp0 pointer in the common tss. This is a lot
simpler since than swithching the gdt[GPROC0_SEL].sd.sd_base pointer
to each process's tss since the esp0 pointer is a 32 bit pointer, and the
sd_base setting is split into three different bit sections at non-aligned
boundaries and requires a lot of twiddling to reset.
The 8K of memory at the top of the process space is now empty, and unmapped
(and unmappable, it's higher than VM_MAXUSER_ADDRESS).
Simplity the pmap code to manage process contexts, we no longer have to
double map the UPAGES, this simplifies and should measuably speed up fork().
The following parts came from John Dyson:
Set PG_G on the UPAGES that are now in kernel context, and invalidate
them when swapping them out.
Move the upages object (upobj) from the vmspace to the proc structure.
Now that the UPAGES (pcb and kernel stack) are out of user space, make
rfork(..RFMEM..) do what was intended by sharing the vmspace
entirely via reference counting rather than simply inheriting the mappings.
convenient and makes life difficult for my next commit. We still need
an i386tss to point to for the tss slot in the gdt, so we use a common
tss shared between all processes.
Note that this is going to break debugging until this series of commits
is finished. core dumps will change again too. :-( we really need
a more modern core dump format that doesn't depend on the pcb/upages.
This change makes VM86 mode harder, but the following commits will remove
a lot of constraints for the VM86 system, including the possibility of
extending the pcb for an IO port map etc.
Obtained from: bde
Use the name argument almost the same in all LKM types. Maintain
the current behavior for the external (e.g., modstat) name for DEV,
EXEC, and MISC types being #name ## "_mod" and SYCALL and VFS only
#name. This is a candidate for change and I vote just the name without
the "_mod".
Change the DISPATCH macro to MOD_DISPATCH for consistency with the
other macros.
Add an LKM_ANON #define to eliminate the magic -1 and associated
signed/unsigned warnings.
Add MOD_PRIVATE to support wcd.c's poking around in the lkm structure.
Change source in tree to use the new interface.
Reviewed by: Bruce Evans
by Alan Cox <alc@cs.rice.edu>, and his description of the problem.
The bug was primarily in procfs_mem, but the mistake likely happened
due to the lack of vm system support for the operation. I added
better support for selective marking of page dirty flags so that
vm_map_pageable(wiring) will not cause this problem again.
The code in procfs_mem is now less bogus (but maybe still a little
so.)
implementation #ifdef out. This can be used for now by NFS. As soon
as all the other filesystems' locking is fixed, this can go away.
Print the vnode address in vprint for easier debugging.
1. imgp->image_header needs to be cleared for the bp == NULL && `goto
interpret' case, else exec_fail_dealloc would free it twice after
an error.
2. Moved the vp->v_writecount check in exec_check_permissions() to
near the end. This fixes execve("/dev/null", ...) returning the
bogus errno ETXTBSY. ETXTBSY is still returned for attempts to
exec interpreted files that are open for writing. The man page
is very old and wrong here. It says that ETXTBSY is for pure
procedure (shared text) files that are open for writing or reading.
3. Moved the setuid disabling in exec_check_permissions() to the end.
Cosmetic. It's more natural to dispose of all the error cases
first.
...plus a couple of other cosmetic changes.
Submitted by: bde
by bde.
Don't return EPERM in setre[ug]id() just because the caller passes in
the current effective id in the second arg (ie: no change), as suggested
by ache.
The magic number conflicted with the rotting disabled one in ext2fs for
debug.doasyncfree.
Removed messy debugging variable/constant/sysctl debug.doreallocblks.
Lite2 removed it, and we don't use the code that it controls.
This is valueable for library code which needs to be able to find out
whether the current process is or *was* set[ug]id at some point in the
past, and may have a "tainted" execution environment. This is especially
a problem with the trend to immediately revoke privs at startup and regain
them for critical sections. One problem with this is that if a cracker
is able to compromise the program while it's still got a saved id, the
cracker can direct the program to regain the privs. Another problem is
that the user may be able to affect the program in some other way (eg:
setting resolver host aliases) and the library code needs to know when it
should disable these sorts of features.
Reviewed by: ache
Inspired by: OpenBSD (but with a different implementation)
that allows traditional BSD setuid/setgid behavior.
The only visible difference should be that a non-root setuid program
(eg: inn's "rnews" program) that is setuid to news, can completely
"become" uid news. (ie: setuid(geteuid()) This was allowed in
traditional 4.2/4.3BSD and is now "blessed" by Posix as a special
case of "appropriate privilige".
Also, be much more careful with the P_SUGID flag so that we can use it
for issetugid() - only set it if something changed.
Reviewed by: ache
vector except for the egid in groups[0]. There is a risk that programs
that come from SYSV/Linux that expect this to work and don't check for
error returns may accidently pass root's groups on to child processes.
We now do what is least suprising (to non BSD programs/programmers) in
this scenario, and nothing is changed for programs written with BSD groups
rules in mind.
Reviewed by: ache
to removing the connection from the queue. The problem here is that
falloc() may block and this would allow another process to accept the
connection instead. If this happens to leave the queue empty, then the
system will panic with an "accept: nothing queued".
Also changed a wakeup() to a wakeup_one() to avoid the "thundering herd"
problem on new connections in Apache (or any other application that has
multiple processes blocked in accept() for the same socket).
as shadows of their containing directory. This should solve the problem
of users not being able to delete their symlinks from /tmp once and for
all.
Symlinks do not have modes though, they are accessable to everything that
can read the directory (as before). They are made to show this fact at
lstat time (they appear as mode 0777 always, since that's how the the
lookup routines in the kernel treat them).
More commits will follow, eg: add a real lchown() syscall and man pages.
centric rather than VM-centric to fix a problem with errors not being
detectable when the header is read.
Killed exech_map as a result of these changes.
There appears to be no performance difference with this change.
they were created later on. This is not the case when processing
syscalls.isc in the ibcs2 area. (It generates no declarations, it's
all either hidden (already prototyped elsewhere) or unimplemented).
<sys/ioctl_compat.h> and sometimes <sys/filio.h> instead of
<sys/ioctl.h> in tty-related files. <sys/ttycom.h> is still
usually imported bogusly via <sys/termios.h>.
<sys/ttycom.h> and sometimes <sys/filio.h> instead of <sys/ioctl.h>
in miscellaneous files. Most of these files have nothing to do
with ttys but need to include <sys/ttycom.h> to get the definitions
of TIOC[SG]PGRP which are (ab)used to convert F[SG]ETOWN fcntls into
ioctls.
automatically have random generation numbers. The kenel way of handling those
also changed. Further it is advised to run fsirand on all your nfs exported
filesystems. the code is mostly copied from OpenBSD, with the randomization
chanegd to use /dev/urandom
Reviewed by: Garrett
Obtained from: OpenBSD
null casts. `time' is nonvolatile for accesses within a region locked
by splclock()/splx(). Accesses outside such a region are invalid, and
splx() must have the side effect of potentially changing all global
variables (since there are hundreds of sort of volatile variables like
`time'), so declaring `time' as volatile didn't have any real benefits.
form `tv = time'. Use a new function gettime(). The current version
just forces atomicicity without fixing precision or efficiency bugs.
Simplified some related valid accesses by using the central function.
processes using AF_LOCAL sockets. This hack is going to be used with
Secure RPC to duplicate a feature of STREAMS which has no real counterpart
in sockets (with STREAMS/TLI, you can apparently use t_getinfo() to learn
UID of a local process on the other side of a transport endpoint).
What happens is this: the client sets up a sendmsg() call with ancillary
data using the SCM_CREDS socket-level control message type. It does not
need to fill in the structure. When the kernel notices the data,
unp_internalize() fills in the cmesgcred structure with the sending
process' credentials (UID, EUID, GID, and ancillary groups). This data
is later delivered to the receiving process. The receiver can then
perform the follwing tests:
- Did the client send ancillary data?
o Yes, proceed.
o No, refuse to authenticate the client.
- The the client send data of type SCM_CREDS?
o Yes, proceed.
o No, refuse to authenticate the client.
- Is the cmsgcred structure the right size?
o Yes, proceed.
o No, signal a possible error.
The receiver can now inspect the credential information and use it to
authenticate the client.
devtotty(). devtotty() must check its arg carefully since the arg is
supplied as ioctl data. This should fix PR3004.
Renamed devtotty() to snpdevtotty().
formula uses `& nchash'. This is very broken when nchash is a prime
number instead of 1 less than a power of 2, but the Lite2 formula was
merged in.
Merged some cosmetic changes from Lite2, rev.1.21 and Lite1. The merge
was difficult because the Lite2 code is essentially ours (phk's) except
where Lite2 improved or broke it.
Summary of the Lite2 changes:
- in the copyright, phk's rights have been transferred to the Regents.
This change should be reviewed.
- nchENOENT went away; the "no" vnode is now simply 0.
- comments were improved.
- style was "improved".
- goto instead of Fanatism (sic) was considered bad :-).
- there are some small changes to support whiteouts.
- new cache entries are added in more cases. More work is required
near here to change the hash table size if kern.desiredvnodes is
changed using sysctl.
- rescanning of the hash bucket in cache_purgevfs() was removed. This
change should be reviewed.
(phk's) sysctl framework, and I needed special code to disambiguate
the VFS_GENERIC node from the VFS_VFSCONF leaf, so I only converted
the leaves to the FreeBSD framework. The error handling isn't quite
right. CSRGS's sysctls seem to return ENOTDIR too much and FreeBSD's
sysctls don't agree with the man page.
and getvfsbyname() interfaces. The new interfaces are now hidden from
applications unless _NEW_VFSCONF is defined. The new vfsconf interfaces
don't work yet.
cruft and resulted in loading usually following a null pointer. Use
something closer to the pre-Lite2 code, including not making a copy of
the new filesystem's config info. Not making a copy also fixes a race
for loading and a memory leak for unloading.
Fixed unloading of vfs's. maxvfsconf wasn't maintained.
Look up the vfs to unload by name instead of by number. The numbers
should go away as soon as all mount utilities are converted.
- getnewvnode() and vref() were missing one simple_unlock() each.
- the Lite2 locking changes weren't merged at all in
printlockedvnodes() or sysctl_vnode(). Merging these undid
some KNF style regressions.
all of the configurables and instrumentation related to
inter-process communication mechanisms. Some variables,
like mbuf statistics, are instrumented here for the first
time.
For mbuf statistics: also keep track of m_copym() and
m_pullup() failures, and provide for the user's inspection
the compiled-in values of MSIZE, MHLEN, MCLBYTES, and MINCLSIZE.
- avoid malloc() if the number of fds is small.
- pack the bits better so that `small' is quite large.
- don't waste time generating zero bits for null fd_set pointers or
scanning these bits.
Possibly improved select():
- free malloc()ed storage before returning. This is simpler and I
think huge select()s aren't worth optimizing since they are rare,
relative gain would be small and there would be tiny costs for all
selects().
Reviewed by: ache (first version by him too)
execve() clears the P_SUGID process flag in execve() if the binary
executed does not have suid or sgid permission bits set.
This also happens when the effective uid is different from the real
uid or the effective gid is different from the real gid. Under
these circumstances, the process still has set id privileges and
the P_SUGID flag should not be cleared.
Submitted by: Tor Egge <Tor.Egge@idt.ntnu.no>
Successful lstat()s purged an existing entry as well as not caching the
result.
This bug was introduced in Lite1 by setting the LOCKPARENT flag for
[o]lstat() in order to support the inherit-attributes-from-parent-
directory misfeature for symlinks. LOCKPARENT was previously only set
for CREATEs and DELETEs. It is now set for LOOKUPs, but only for
[o]lstat(), so the problem wasn't very noticeable.
the old VFS_VFSCONF sysctl is enabled by default.
Initialize the vfc_vfsops field to non-NULL in sysctl_ovfs_conf()
so that the old VFS_VFSCONF sysctl actually works. The old (still
current) getvfsent.c uses this "kernel-only" field to decide which
vfs's are configured (the old implementation returned null entries
for unconfigured vfs's).
to coredump previously since it (somewhat uniquely) is setuid and forks
without execing, and thus without passing P_SUGID the child could
coredump and possibly divulge sensitive information (such as encrypted
passwords from the passwd database).
clusters greater than one page in length by calling contigmalloc1().
This uses a helper process `mclalloc' to do the allocation if
the system runs out at interrupt time to avoid calling contigmalloc
at high spl. It is not yet clear to me whether this works.
sb_max * MCLBYTES / (MSIZE + MCLBYTES)
used in sbreserve() to overflow, causing all socket creation attempts
to fail. Force the calculation to use u_quad_t's, which makes overflow
less likely.
changes, so don't expect to be able to run the kernel as-is (very well)
without the appropriate Lite/2 userland changes.
The system boots and can mount UFS filesystems.
Untested: ext2fs, msdosfs, NFS
Known problems: Incorrect Berkeley ID strings in some files.
Mount_std mounts will not work until the getfsent
library routine is changed.
Reviewed by: various people
Submitted by: Jeffery Hsu <hsu@freebsd.org>
The limit is now only used by init, so it may as well be "infinite".
Don't use RLIM_INFINITY, since setrlimit() doesn't allow setting
that value. Use maxfiles instead of RLIM_INFINITY for the hard
limit for the same reason.
Similarly for the maxprocesses limits (use the "infinite" value of
maxproc instead if MAXUPRC and RLIM_INFINITY).
NOFILES, MAXUPRC, CHILD_MAX and OPEN_MAX are no longer used in
/usr/src and should go away. Their values are almost guaranteed to
be wrong now that login.conf exists, so anything that uses the values
is broken. Unfortunately, there are probably a lot of ports that
depend on them being defined.
The global limits maxfilesperproc and maxprocperuid should go away
too.
on it.
makesyscalls.sh:
This parsed $Id$. Fixed(?) to parse $FreeBSD$. The output is wrong when
the id is not expanded in the source file.
syscalls.master:
Fixed declaration of sigsuspend(). There are still some bogons and
spam involving sigset_t.
Use `struct foo *' instead of the equivalent `foo_t *' for some nfs and
lfs syscalls so that <sys/sysproto.h> doesn't depend on <sys/mount.h>.
variable `kern.maxvnodes' which gives much better control over vnode
allocation than EXTRAVNODES (except in -current between 1995/10/28 and
1996/11/12, kern.maxvnodes was read-only and thus useless).
when allocating memory for network buffers at interrupt time. This is due
to inadequate checking for the new mcl_map. Fixed by merging mb_map and
mcl_map into a single mb_map.
Reviewed by: wollman
rev.1.10 two years ago. Children continued to run at splhigh()
after returning from vm_fork(). This mainly affected kernel
processes and init. For ordinary processes, interrupts are normally
unmasked a few instructions later after fork() returns (it may be
important for syscall() not to reschedule the child processes).
Kernel processes had workarounds for the problem. Init manages to
start because some routines "know" that it is safe to go to sleep
despite their caller starting them at a high ipl. Then its ipl
gets fixed on its first normal return from a syscall.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
Firstly, now our read-ahead clustering is on a file descriptor basis and not
on a per-vnode basis. This will allow multiple processes reading the
same file to take advantage of read-ahead clustering. Secondly, there
previously was a problem with large reads still using the ramp-up
algorithm. Of course, that was bogus, and now we read the entire
"chunk" off of the disk in one operation. The read-ahead clustering
algorithm should use less CPU than the previous also (I hope :-)).
NOTE: THAT LKMS MUST BE REBUILT!!!
Broke locking on named pipes in the same way as locking on non-vnodes
(wrong errno). This will be fixed later.
The fix involves negative logic. Named pipes are now distinguished from
other types of files with vnodes, and there is additional code to handle
vnodes and named pipes in the same way only where that makes sense (not
for lseek, locking or TIOCSCTTY).
This makes unexpected faults (in an interrupt handler) more likely
to crash properly. It could be done even better (more robustly and
more efficiently) using lazy fault handling.
modules sort of works now. Their devswitch entries aren't cleaned
up, so accessing them after they have been unloaded causes a panic
in spec_open().
Submitted by: durian@plutotech.com (Mike Durian), IIRC
Most of the standard utilities that depended on (or were broken in
a different way by) the old behaviour of interpreting "" as "."
were fixed a year or two ago. There is still a fairly harmless
bug in tar and a harmless bug in gzip. Tar apparently replaces
"/" by "" when it strips leading slashes.
decrease the size of buffer_map to approx 2/3 of what it used to be
(buffer_map can be smaller now.) The original commit of these changes
increased the size of buffer_map to the point where the system would
not boot on large systems -- now large systems with large caches will
have even less problems than before.
the sd & od drivers. There is also slight changes to fdisk & newfs
in order to comply with different sectorsizes.
Currently sectors of size 512, 1024 & 2048 are supported, the only
restriction beeing in fdisk, which hunts for the sectorsize of
the device.
This is based on patches to od.c and the other system files by
John Gumb & Barry Scott, minor changes and the sd.c patches by
me.
There also exist some patches for the msdos filesys code, but I
havn't been able to test those (yet).
John Gumb (john@talisker.demon.co.uk)
Barry Scott (barry@scottb.demon.co.uk)
scheme. Additionally, add the capability for checking for unexpected
kernel page faults. The maximum amount of kva space for buffers hasn't
been decreased from where it is, but it will now be possible to do so.
This scheme manages the kva space similar to the buffers themselves. If
there isn't enough kva space because of usage or fragementation, buffers
will be reclaimed until a buffer allocation is successful. This scheme
should be very resistant to fragmentation problems until/if the LFS code
is fixed and uses the bogus buffer locking scheme -- but a 'fixed' LFS
is not likely to use such a scheme.
Now there should be NO problem allocating buffers up to MAXPHYS.
succeeds. Writing an action now succeeds iff the handler isn't changed.
(POSIX allows attempts to change the handler to be ignored or cause an
error. Changing other parts of the action is allowed (except attempts
to mask unmaskable signals are silently ignored as usual).)
Found by: NIST-PCTS
the queues and generate a SIGINT. Previously, this wasn't done if ISIG
was clear or the VINTR character was disabled, and it was done by
converting the BREAK to a VINTR character and sometimes bogusly echoing
this character.
Found by: NIST-PCTS
larger than the vfs layer can provide. We now automatically support
32K clusters if MSDOSFS is installed, and panic if a filesystem tries
to allocate a buffer larger than MAXBSIZE.
This commit is a result of some "prodding" by BDE.
substantially increasing buffer space. Specifically, we double
the number of buffers, but allocate only half the amount of memory
per buffer. Note that VDIR files aren't cached unless instantiated
in a buffer. This will significantly improve caching.
using a sockaddr_dl.
Fix the other packet-information socket options (SO_TIMESTAMP, IP_RECVDSTADDR)
to work for multicast UDP and raw sockets as well. (They previously only
worked for unicast UDP).
(1) deleted #if 0
pc98/pc98/mse.c
(2) hold per-unit I/O ports in ed_softc
pc98/pc98/if_ed.c
pc98/pc98/if_ed98.h
(3) merge more files by segregating changes into headers.
new file (moved from pc98/pc98):
i386/isa/aic_98.h
deleted:
well, it's already in the commit message so I won't repeat the
long list here ;)
Submitted by: The FreeBSD(98) Development Team
If DEVFS is configured, create devfs devices for previously invisible
partitions on the slices.
Fixed an old aliasing bug which caused E=17 errors from DEVFS for
DIOCSDINFO when there were no real slices.
I decided to do this for every hardclock() call instead of lazily
in microtime(). The lazy method is simpler but has more overhead
if microtime() is called a lot.
CPU_THISTICKLEN() is now a no-op and should probably go away.
Previously it did nothing directly but had the side effect of
setting i586_last_tick for CPU_CLOCKUPDATE() and i586_avg_tick for
debugging. CPU_CLOCKUPDATE() now uses a better method and
i586_avg_tick is too much trouble to maintain.
Reduced nesting of #includes in the usual case.
Increased nesting of #includes when CLOCK_HAIR is defined. This
is a kludge to get typedefs for inline functions only when the
inline functions are used. Normally only kern_clock.c defines
this. kern_clock.c can't include the i386 headers directly.
Removed unused LOCORE support.
- use a more accurate and more efficient method of compensating for
overheads. The old method counted too much time against leaf
functions.
- normally use the Pentium timestamp counter if available.
On Pentiums, the times are now accurate to within a couple of cpu
clock cycles per function call in the (unlikely) event that there
are no cache misses in or caused by the profiling code.
- optionally use an arbitrary Pentium event counter if available.
- optionally regress to using the i8254 counter.
- scaled the i8254 counter by a factor of 128. Now the i8254 counters
overflow slightly faster than the TSC counters for a 150MHz Pentium :-)
(after about 16 seconds). This is to avoid fractional overheads.
files.i386:
permon.c temporarily has to be classified as a profiling-routine
because a couple of functions in it may be called from profiling code.
options.i386:
- I586_CTR_GUPROF is currently unused (oops).
- I586_PMC_GUPROF should be something like 0x70000 to enable (but not
use unless prof_machdep.c is changed) support for Pentium event
counters. 7 is a control mode and the counter number 0 is somewhere
in the 0000 bits (see perfmon.h for the encoding).
profile.h:
- added declarations.
- cleaned up separation of user mode declarations.
prof_machdep.c:
Mostly clock-select changes. The default clock can be changed by
editing kmem. There should be a sysctl for this.
subr_prof.c:
- added copyright.
- calibrate overheads for the new method.
- documented new method.
- fixed races and and machine dependencies in start/stop code.
mcount.c:
Use the new overhead compensation method.
gmon.h:
- changed GPROF4 counter type from unsigned to int. Oops, this should
be machine-dependent and/or int32_t.
- reorganized overhead counters.
Submitted by: Pentium event counter changes mostly by wollman
add free vnodes back to the freelist. They must do their own vnode
management. Anyway, this change is *only* activated with their filesystem
and doesn't affect anyone else. Whoops, forgot the submitted-by lines
in my previous commits too.. :-(
Submitted-By: Tony Ardolino <tony@netcon.com>
The heuristic for managment of memory backing the buffer cache was
nice, but didn't work due to some architectural problems. Simplify
and improve the algorithm.
capable of being used for things other than swap space allocation,
and splvm would have been appropriate for only swap space allocation
and other VM things. My commit broke that (and was actually a mistake.)
previous snap. Specifically, kern_exit and kern_exec now makes a
call into the pmap module to do a very fast removal of pages from the
address space. Additionally, the pmap module now updates the PG_MAPPED
and PG_WRITABLE flags. This is an optional optimization, but helpful
on the X86.
(yes I had tested the hell out of this).
I've also temporarily disabled the code so that it behaves as it previously
did (tail drop's the syns) pending discussion with fenner about some socket
state flags that I don't fully understand.
Submitted by: fenner
Major: When blocking occurs in allocbuf() for VMIO files,
excess wire counts could accumulate.
Major: Pages are incorrectly accumulated into the physical
buffer for clustered reads. This happens when bogus
page is needed.
Minor: When reclaiming buffers, the async flag on the buffer
needs to be zero, or the reclaim is not optimal.
Minor: The age flag should be cleared, if a buffer is wanted.
1/ session leader
2/ Have a console device vnode (/dev/console)
3/ have NULL pointer for a consoel tty struct.
fix the only case where the tty struct is referenced without a prior
check for existance.
- kern.maxproc and kern.maxprocperuid were read-only (and thus essentially
useless. Apparently no one uses them).
- all the user sysctls were read-write (and thus it was possible for them
to be inconsistent with the authoritative fixed values in the library).
Removed unused #include.
It is needed for implementation details but very little of it is
needed for the interface. Include it in the few places that didn't
already include it.
Include <sys/ioccom.h> in <sys/disklabel.h> (as already in
<sys/diskslice.h>) so that all the disk-related headers are almost
self-sufficient.
incorrect, and correct the support for B_ORDERED. The spl window
fix was from Peter Wemm, and his questions led me to find the problem with
the interrupt time page manipulation.
data pointed at in a ktrace file, if this process is being ktrace'ed.
I'm using this to profile malloc usage.
The advantage is that there is no context around this call, ie, no
open file or socket, so it will work in any process, and you can
decide if you want it to collect data or not.
/*
* Structure defined by POSIX.4 to be like a timeval.
*/
struct timespec {
time_t ts_sec; /* seconds */
long ts_nsec; /* and nanoseconds */
};
The correct names of the fields are tv_sec and tv_nsec.
Reminded by: James Drobina <jdrobina@infinet.com>
B_ASYNC flag broke things pretty bad (freeing buffer already on
queue or other wierd buffer queue errors.) The broken code is
left in commented out, but this makes the problem go away for
now.
The default level works with minimal overhead, but one can also enable
full, efficient use of a 512K cache. (Parameters can be generated
to support arbitrary cache sizes also.)
for entire SYS5 SHM segments. This is totally unnecessary, and so the
correct allocation of VM objects has been substituted. (The vm_mmap
was misused -- vm_object_allocate is more appropriate.)
Bowrite guarantees that buffers queued after a call to bowrite will
be written after the specified buffer (on a particular device).
Bowrite does this either by taking advantage of hardware ordering support
(e.g. tagged queueing on SCSI devices) or resorting to a synchronous write.
were declared as non-const. This is backwards (_lkm_exec() changes the
pointers but all the target `struct execsw's are const). Fixed this
and poisoned related declarations to match and removed the bogus casts
that hid the bug.
the file access time update on reads and can be useful in reducing
filesystem overhead in cases where the access time is not important (like
Usenet news spools).
the primary and secondary return codes, causing it to not behave as
documented. This probably originates from the ancient BSD kernels that
had pipe(2) implemented by socketpair(2), there are no binaries left that
we can run that do this.
Pointed out by: Robert Withrow <witr@rwwa.com>, PR#731
note that at_shutdown has a new parameter to indicate When
during a shutdown the callout should be made. also
add a RB_POWEROFF flag to reboot "howto" parameter..
tells the reboot code in our at_shutdown module to turn off the UPS
and kill the power. bound to be useful eventually on laptops
The interface into the "VMIO" system has changed to be more consistant
and robust. Essentially, it is now no longer necessary to call vn_open
to get merged VM/Buffer cache operation, and exceptional conditions
such as merged operation of VBLK devices is simpler and more correct.
This code corrects a potentially large set of problems including the
problems with ktrace output and loaded systems, file create/deletes,
etc.
Most of the changes to NFS are cosmetic and name changes, eliminating
a layer of subroutine calls. The direct calls to vput/vrele have
been re-instituted for better cross platform compatibility.
Reviewed by: davidg
half way through the range rather than possibly colliding with
fixed elements. Increase the size of the arrays to take this into account..
remember that each element in the array is now only 1 ponter so this
isn't that much..
also note a possible bug in debugging code in uipc_socket2.c (add XXX)
I've been meaning to do this for AGES as I keep having to patch those routines
whenever I write a proprietary package or similar..
any module that assigns resources to processes needs to know when
these events occur. there are existsing modules that should be modified
to take advantage of these.. e.g. SYSV IPC primatives
presently have #ifdef entries in exit()
this also helps with making LKMs out of such things..
(see the man pages at_exit(9) and at_fork(9))
called kern_shutdown.c
note: I couldn't see anything machine dependant in the
functions boot() and dumpsys() which were in machdep.c
I have left a prototype for cpu_boot() which would go in
machdep.c, but I have nothing to put in it. Iexpect others will
let me know in no uncertain ways that this or that is machine dependant
and should be there, but I'll way for that to happen.. :)
I haven't actually taken the functions OUT of machdep
or anywhere else yet.. I'm checking in this file so others can have a look
at it and comment. SO PLEASE DO COMMENT!
I am also (in another checkin) addinf a man(9) page for the new
at_shotdown().. er freudian slip there.. at_shutdown() call
so have a look at that (and at_exit and at_fork as well)
and feed me comments..
I'll heck in the changes to make these (shutdown) changes active tomorrow
if no-one objects too strongly..
Fixes unp_externalize panic which occurs when a process is at it's
ulimit for file descriptors and tries to receive a file descriptor from
another process.
Reviewed by: wollman
block number.. (assuming Debugger() returned). The disk drivers assume
that dscheck() sets both error markers (bp->b_error and set B_ERROR in
bp->b_flags) if it fails.
problem with the 'shell scripts' was found, but there was a 'strange'
problem found with a 486 laptop that we could not find. This commit
backs the code back to 25-jul, and will be re-entered after the snapshot
in smaller (more easily tested) chunks.
performance issues.
1) The pmap module has had too many inlines, and so the
object file is simply bigger than it needs to be.
Some common code is also merged into subroutines.
2) Removal of some *evil* PHYS_TO_VM_PAGE macro calls.
Unfortunately, a few have needed to be added also.
The removal caused the need for more vm_page_lookups.
I added lookup hints to minimize the need for the
page table lookup operations.
3) Removal of some bogus performance improvements, that
mostly made the code more complex (tracking individual
page table page updates unnecessarily). Those improvements
actually hurt 386 processors perf (not that people who
worry about perf use 386 processors anymore :-)).
4) Changed pv queue manipulations/structures to be TAILQ's.
5) The pv queue code has had some performance problems since
day one. Some significant scalability issues are resolved
by threading the pv entries from the pmap AND the physical
address instead of just the physical address. This makes
certain pmap operations run much faster. This does
not affect most micro-benchmarks, but should help loaded system
performance *significantly*. DG helped and came up with most
of the solution for this one.
6) Most if not all pmap bit operations follow the pattern:
pmap_test_bit();
pmap_clear_bit();
That made for twice the necessary pv list traversal. The
pmap interface now supports only pmap_tc_bit type operations:
pmap_[test/clear]_modified, pmap_[test/clear]_referenced.
Additionally, the modified routine now takes a vm_page_t arg
instead of a phys address. This eliminates a PHYS_TO_VM_PAGE
operation.
7) Several rewrites of routines that contain redundant code to
use common routines, so that there is a greater likelihood of
keeping the cache footprint smaller.
Saves about 280 butes of source per driver, 56 bytes in object size
and another 56 bytes moves from data to bss.
No functional change intended nor expected.
GENERIC should be about one k smaller now :-)
Fixed initialization of pipe_pgid - don't default to pid 0 (swapper) for
SIGIO.
Added comments about other implicit initializations, mostly for struct
stat.
Fixed initialization of st_mode. S_IFSOCK was for when pipes were sockets.
It is probably safe to fix the bogus S_ISFIFO() now that pipes can be
distinguished from sockets in all cases.
Don't return ENOSYS for inappropriate ioctls.
for big positive adjustments. The existence of big adjustments may
be a bug (it's not documented...) but there was no good reason for
the asymmetric behaviour.
Reviewed by: wollman
pr_usrreq mechanism which was poorly designed and error-prone. This
commit renames pr_usrreq to pr_ousrreq so that old code which depended on it
would break in an obvious manner. This commit also implements the new
interface for TCP, although the old function is left as an example
(#ifdef'ed out). This commit ALSO fixes a longstanding bug in the
TCP timer processing (introduced by davidg on 1995/04/12) which caused
timer processing on a TCB to always stop after a single timer had
expired (because it misinterpreted the return value from tcp_usrreq()
to indicate that the TCB had been deleted). Finally, some code
related to polling has been deleted from if.c because it is not
relevant t -current and doesn't look at all like my current code.
the high kernel calls into a protocol stack to perform requests on the
user's behalf. We replace the pr_usrreq() entry in struct protosw with a
pointer to a structure containing pointers to functions which implement
the various reuqests; each function is declared with the correct type and
number of arguments. (This is unlike the current scheme in which a quarter
of the requests take arguments of type other than (struct mbuf *) and the
difference is papered over with casts.) There are a few benefits to this
new scheme:
1) Arguments are passed with their correct types, and null-pointer dummies
are no longer necessary.
2) There should be slightly better caching effects from eliminating
the prximity to extraneous code and th switch in pr_usrreq().
3) It becomes much easier to change the types of the arguments to something
other than `struct mbuf *' (e.g.,pushing the work of sosend() into
the protocol as advocated by Van Jacobson).
There is one principal drawback: existing protocol stacks need to
be modified. This is alleviated by compatibility code in
uipc_socket2.c and uipc_domain.c which emulates the new interface
in terms of the old and vice versa.
This idea is not original to me. I read about what Jacobson did
in one of his papers and have tried to implement the first steps
towards something like that here. Much work remains to be done.
The i386 pmap module uses a special area of kernel virtual memory for mapping
of page tables pages when it needs to modify another process's virtual
address space. It's called the 'alternate page table map'. There is only one
of them and it's expected that only one process will be using it at once and
that the operation is atomic.
When the merged VM/buffer cache was implemented over a year ago, it became
necessary to rundown VM pages at I/O completion. The unfortunate and
unforeseen side effect of this is that pmap functions are now called at bio
interrupt time. If there happend to be a process using the alternate page
table map when this I/O completion occurred, it was possible for a different
process's address space to be switched into the alternate page table map -
leaving the current pmap process with the wrong address space mapped when
the interrupt completed. This resulted in BAD things happening like pages
being mapped or removed from the wrong address space, etc.. Since a very
common case of a process modifying another process's address space is during
fork when the kernel stack is inserted, one of the most common manifestations
of this bug was the kernel stack not being mapped properly, resulting in a
silent hang or reboot. This made it VERY difficult to troubleshoot this bug
(I've been trying to figure out the cause of this for >6 months). Fortunately,
the set of conditions that must be true before this problem occurs is
sufficiently rare enough that most people never saw the bug occur. As I/O
rates increase, however, so does the frequency of the crashes. This problem
used to kill wcarchive about every 10 days, but in more recent times when
the traffic exceeded >100GB/day, the machine could barely manage 6 hours of
uptime.
The fix is to make certain that no process has the pages mapped that are
involved in the I/O, before the I/O is started. The pages are made busy, so
no process will be able to map them, either, until the I/O has finished.
This side-steps the issue by still allowing the pmap functions to be called
at interrupt time, but also assuring that the alternate page table map won't
be switched.
Unfortunately, this appears to not be the only cause of this problem. :-(
Reviewed by: dyson
was due to non-aligned 64K transfers taking 17 pages. We currently
do not support >16 page transfers. The transfer is unfortunately truncated,
but since buffers are usually malloced, this is a problem only once in
a while. Savecore is a culprit, but tar/cpio usually aren't. This
is NOT the final fix (which is likely a bouncing scheme), but will at
least keep the system from crashing.
Fixed profiling of system times. It was pre-4.4Lite and didn't support
statclocks. System times were too small by a factor of 8.
Handle deferred profiling ticks the 4.4Lite way: use addupc_task() instead
of addupc(). Call addupc_task() directly instead of using the ADDUPC()
macro.
Removed vestigial support for PROFTIMER.
switch.s:
Removed addupc().
resourcevar.h:
Removed ADDUPC() and declarations of addupc().
cpu.h:
Updated a comment. i386's never were tahoe's, and the deferred profiling
tick became (possibly) multiple ticks in 4.4Lite.
Obtained from: mostly from NetBSD
compiler warnings which occur if you don't have 'options DEVFS' in
your kernel config file:
../../kern/kern_descrip.c: In function `fildesc_drvinit':
../../kern/kern_descrip.c:1103: warning: unused variable `fd'
../../kern/kern_descrip.c: At top level:
../../kern/kern_descrip.c:1095: warning: `devfs_token_stdin' defined but not use
d
../../kern/kern_descrip.c:1096: warning: `devfs_token_stdout' defined but not us
ed
../../kern/kern_descrip.c:1097: warning: `devfs_token_stderr' defined but not us
ed
../../kern/kern_descrip.c:1098: warning: `devfs_token_fildesc' defined but not u
sed
to match (pc98/random_machdep.c probably requires a similar change). This
is a problem area for the PC98 merge - all PC98 ifdefs in <machine/*.h> are
kludges to work around incorrect layering.
disklabel(8) to the kernel (dsopen()). Drivers should initialize the
hardware values (rpm, interleave, skews). Drivers currently don't do
this, but it usually doesn't matter since rotational position stuff is
normally disabled.
All new code is "#ifdef PC98"ed so this should make no difference to
PC/AT (and its clones) users.
Ok'd by: core
Submitted by: FreeBSD(98) development team
It is called from copyin and copyout.
The new routine is conditioned on I586_CPU and I586_FAST_BCOPY, so you
need
options "I586_FAST_BCOPY"
(quotes essenstial) in your kernel config file.
Also, if you have other kernel types configured in your kernel, an
additional check to make sure it is running on a Pentium is inserted.
(It is not clear why it doesn't help on P6s, it may be just that the
Orion chipset doesn't prefetch as efficiently as Tritons and friends.)
Bruce can now hack this away. :)
it assumes all of the data exists in the kernel. Also, fix
sysctl_new-kernel (unused until now) which had reversed operands to
bcopy().
Reviewed by: phk
Poul writes:
... actually the lock/sleep/wakeup cruft shouldn't be needed in the
kernel version I think, but just leave it there for now.
any statclock ticks. Pretend that all the time up to the first
statclock tick is system time. . This makes a difference mainly for
benchmarks that test short-lived processes - the user and system
times for processes that each lived for about 1ms only added up to
about 10% of the real time even when there was very little interrupt
activity.
Break the printing of a quad_t variable correctly.
gcc only inlines memcpy()'s whose count is constant and didn't inline
these. I want memcpy() in the kernel go away so that it's obvious that
it doesn't need to be optimized. Now it is only used for one struct
copy in si.c.
code without the B_READ flag being set. This is a problem when the
data is not cached, and the result will be a bogus attempted write.
Submitted by: Kato Takenori <kato@eclogite.eps.nagoya-u.ac.jp>
to be allocated at boot time. This is an expensive option, as they
consume physical ram and are not pageable etc. In certain situations,
this kind of option is quite useful, especially for news servers that
access a large number of directories at random and torture the name cache.
Defining 5000 or 10000 extra vnodes should cut down the amount of vnode
recycling somewhat, which should allow better name and directory caching
etc.
This is a "your mileage may vary" option, with no real indication of
what works best for your machine except trial and error. Too many will
cost you ram that you could otherwise use for disk buffers etc.
This is based on something John Dyson mentioned to me a while ago.
(returns EPERM always, the errno is specified by POSIX).
If you really have a desperate need to link or unlink a directory, you
can use fsdb. :-)
This should stop any chance of ftpd, rdist, "rm -rf", etc from
bugging out and damaging the filesystem structure or loosing races
with malicious users.
Reviewed by: davidg, bde
contributions or ideas from Stephen McKay <syssgm@devetir.qld.gov.au>,
Alan Cox <alc@cs.rice.edu>, David Greenman <davidg@freebsd.org> and me:
More usage of the TAILQ macros. Additional minor fix to queue.h.
Performance enhancements to the pageout daemon.
Addition of a wait in the case that the pageout daemon
has to run immediately.
Slightly modify the pageout algorithm.
Significant revamp of the pmap/fork code:
1) PTE's and UPAGES's are NO LONGER in the process's map.
2) PTE's and UPAGES's reside in their own objects.
3) TOTAL elimination of recursive page table pagefaults.
4) The page directory now resides in the PTE object.
5) Implemented pmap_copy, thereby speeding up fork time.
6) Changed the pv entries so that the head is a pointer
and not an entire entry.
7) Significant cleanup of pmap_protect, and pmap_remove.
8) Removed significant amounts of machine dependent
fork code from vm_glue. Pushed much of that code into
the machine dependent pmap module.
9) Support more completely the reuse of already zeroed
pages (Page table pages and page directories) as being
already zeroed.
Performance and code cleanups in vm_map:
1) Improved and simplified allocation of map entries.
2) Improved vm_map_copy code.
3) Corrected some minor problems in the simplify code.
Implemented splvm (combo of splbio and splimp.) The VM code now
seldom uses splhigh.
Improved the speed of and simplified kmem_malloc.
Minor mod to vm_fault to avoid using pre-zeroed pages in the case
of objects with backing objects along with the already
existant condition of having a vnode. (If there is a backing
object, there will likely be a COW... With a COW, it isn't
necessary to start with a pre-zeroed page.)
Minor reorg of source to perhaps improve locality of ref.
(PR #1178).
Define a new SO_TIMESTAMP socket option for datagram sockets to return
packet-arrival timestamps as control information (PR #1179).
Submitted by: Louis Mamakos <loiue@TransSys.com>
the past, since it returns to the old system of allocating mbufs out of
a private area rather than using the kernel malloc(). While this may seem
like a backwards step to some, the new allocator is some 20% faster than
the old one and has much better caching properties.
Written by: John Wroclawski <jtw@lcs.mit.edu>
very busy servers (eg: news, web). This is an interaction between
embryonic processes that have not yet finished forking, and happen to
cause the kernel VM space to grow, hitting the uninitialised variable.
It was possible for this to strike at any time, depending on the size of
your kernel and load patterns. One machine had paniced occasionally
when cron launches a job since before the 2.1 release.
If you had "options DIAGNOSTIC", you may have seen references to bogus
addresses like 0xdeadc142 and the like.
This is a minimal change to fix the problem, it will probably be done
better by reordering p_vmspace to be in the startzero section, but it
becomes harder to validate then.
It's been vulnerable since pmap.c rev 1.40 (Jan 9, 1995), so it's been a
cause of problems since well before 2.0.5. This was when the merged
VM/buffer cache and the dynamic growing kernel VM space were first
committed. This probably fixes a few of PR's.
and B_READ before writing. This was was fatal. They also broke the
clearing of B_INVAL before doing i/o. This didn't actually matter.
Submitted by: mostly by joerg
compatibility slice. They were forgotten on last-close and then
creating them on first-open failed.
Devfs entries for slices other than the one containing the root file
system are still invisible unless you open a non-devfs inode on the
slice.
forked child to be dissociated from the parent).
Cleanup fork1(), implement vfork() and fork() in terms of rfork() flags.
Remove RFENVG, RFNOTEG, RFCNAMEG, RFCENVG which are Plan9 specific and cannot
possibly be implemented in FreeBSD.
Renumbered the flags to make up for the removal of the above flags.
Reviewed by: peter, smpatel
Submitted by: Mike Grupenhoff <kashmir@umiacs.umd.edu>
was duplicated until the canq filled up, and write() normally returned 0.
This case is apparently rare. It was reported for Jove's shell buffer in
PR 1130.
Make the SA_NODEFER handling more correct, previously if you called
sigaction to set a handler and had SA_NODEFER set, and manually masked
the signal itself in sa_mask, and when you read the settings back later,
you'd find SA_NODEFER incorrectly cleared.
Pointed out by: bde
the process's memory, it was possible for the procfs_domem() call to
return a residual leftover, but with no errno. Since this is no good for
ptrace which ignored the the residual, remap a leftover amount into an
errno rather than fooling the caller into thinking it was successful when
in fact it was not.
Submitted by: bde (a very long time ago :-)
Made the devfs `fd' devices bug for bug compatible with the ones created
by MAKEDEV:
- ownership is bin.bin, not root.wheel, except for std*. The devfsext
interface doesn't seem to allow specifying the ownership of /devfs/fd,
so it's still incompatible.
- std* aren't links to fd/[0-2].
Added scsi control devices.
Converted almost everything that I changed to use devfs_add_devswf()
and verbose id macros.
st.c:
Renamed enrst* to erst* since that's what the current name is (enrst
seems to be an old name).
vm_offset_t is currently unsigned long but should probably be plain
unsigned for i386's to match the choice of minimal types to represent
for fixed-width types in Lite2. Anyway, it shouldn't be assumed
to be unsigned long.
I only fixed the type mismatches that were detected when I changed
vm_offset_t to unsigned. Only pointer type mismatches were detected.
but didn't actually do anything with it (*blush*).
This should fix bde's test case where the test program set SA_RESETHAND
and when reading it back, it was gone.
Tweak/optimize SA_NODEFER so that the implementation is a little simpler
and does not incur (slight) overhead for every signal at delivery time.
files are off the vendor branch, so this should not change anything.
A "U" marker generally means that the file was not changed in between
the 4.4Lite and Lite-2 releases, and does not need a merge. "C" generally
means that there was a change.
[note new unused (in this form) syscalls.conf, to be 'cvs rm'ed]
the obsolete soqinsque and soqremque functions as well as collapsing
so_q0len and so_qlen into a single queue length of unaccepted connections.
Now the queue of unaccepted & complete connections is checked directly
for queued sockets. The new code should be functionally equivilent to
the old while being substantially faster - especially in cases where
large numbers of connections are often queued for accept (e.g. http).
Compile and link a new kernel, that will give native ELF support, and
provide the hooks for other ELF interpreters as well.
To make native ELF binaries use John Polstras elf-kit-1.0.1..
For the time being also use his ld-elf.so.1 and put it in
/usr/libexec.
The Linux emulator has been enhanced to also run ELF binaries, it
is however in its very first incarnation.
Just get some Linux ELF libs (Slackware-3.0) and put them in the
prober place (/compat/linux/...).
I've ben able to run all the Slackware-3.0 binaries I've tried
so far.
(No it won't run quake yet :)
residing in a buffer that had been dirtied by a process was being
handled incorrectly. The pages were mistakenly placed into the
cache queue. This would likely have the effect of mmaped page modifications
being lost when I/O system calls were being used simultaneously to
the same locations in a file.
Submitted by: davidg
on in the FreeBSD development, I had made a global lock around the
rlist code. This was bogus, and now the lock is maintained on a
per resource list basis. This now allows the rlist code to be used for
almost any non-interrupt level application.
linux binaries from the *BSD a.out loader. This is a hack, but lets me run
static NetBSD binaries. Dynamic binaries are a much bigger problem because
the shared libraries would conflict with our native libraries, so a
/compat/netbsd alternate namespace and translation would be needed.
netscape-2.0 for Linux running all the Java stuff. The scrollbars are now
working, at least on my machine. (whew! :-)
I'm uncomfortable with the size of this commit, but it's too
inter-dependant to easily seperate out.
The main changes:
COMPAT_LINUX is *GONE*. Most of the code has been moved out of the i386
machine dependent section into the linux emulator itself. The int 0x80
syscall code was almost identical to the lcall 7,0 code and a minor tweak
allows them to both be used with the same C code. All kernels can now
just modload the lkm and it'll DTRT without having to rebuild the kernel
first. Like IBCS2, you can statically compile it in with "options LINUX".
A pile of new syscalls implemented, including getdents(), llseek(),
readv(), writev(), msync(), personality(). The Linux-ELF libraries want
to use some of these.
linux_select() now obeys Linux semantics, ie: returns the time remaining
of the timeout value rather than leaving it the original value.
Quite a few bugs removed, including incorrect arguments being used in
syscalls.. eg: mixups between passing the sigset as an int, vs passing
it as a pointer and doing a copyin(), missing return values, unhandled
cases, SIOC* ioctls, etc.
The build for the code has changed. i386/conf/files now knows how
to build linux_genassym and generate linux_assym.h on the fly.
Supporting changes elsewhere in the kernel:
The user-mode signal trampoline has moved from the U area to immediately
below the top of the stack (below PS_STRINGS). This allows the different
binary emulations to have their own signal trampoline code (which gets rid
of the hardwired syscall 103 (sigreturn on BSD, syslog on Linux)) and so
that the emulator can provide the exact "struct sigcontext *" argument to
the program's signal handlers.
The sigstack's "ss_flags" now uses SS_DISABLE and SS_ONSTACK flags, which
have the same values as the re-used SA_DISABLE and SA_ONSTACK which are
intended for sigaction only. This enables the support of a SA_RESETHAND
flag to sigaction to implement the gross SYSV and Linux SA_ONESHOT signal
semantics where the signal handler is reset when it's triggered.
makesyscalls.sh no longer appends the struct sysentvec on the end of the
generated init_sysent.c code. It's a lot saner to have it in a seperate
file rather than trying to update the structure inside the awk script. :-)
At exec time, the dozen bytes or so of signal trampoline code are copied
to the top of the user's stack, rather than obtaining the trampoline code
the old way by getting a clone of the parent's user area. This allows
Linux and native binaries to freely exec each other without getting
trampolines mixed up.
