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.
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.
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.
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).
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>
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.
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
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))
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.
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>
kern_fork.c: add the tiny bit of code for rfork operation.
kern/sysv_*: shmfork() takes one less arg, it was never used.
sys/shm.h: drop "isvfork" arg from shmfork() prototype
sys/param.h: declare rfork args.. (this is where OpenBSD put it..)
sys/filedesc.h: protos for fdshare/fdcopy.
vm/vm_mmap.c: add minherit code, add rounding to mmap() type args where
it makes sense.
vm/*: drop unused isvfork arg.
Note: this rfork() implementation copies the address space mappings,
it does not connect the mappings together. ie: once the two processes
have split, the pages may be shared, but the address space is not. If one
does a mmap() etc, it does not appear in the other. This makes it not
useful for pthreads, but it is useful in it's own right for having
light-weight threads in a static shared address space.
Obtained from: Original by Ron Minnich, extended by OpenBSD
structs and prototypes for syscalls.
Ifdefed duplicated decentralized declarations of args structs. It's
convenient to have this visible but they are hard to maintain. Some
are already different from the central declarations. 4.4lite2 puts
them in comments in the function headers but I wanted to avoid the
large changes for that.
Prototypes are located in <sys/sysproto.h>.
Add appropriate #include <sys/sysproto.h> to files that needed
protos from systm.h.
Add structure definitions to appropriate files that relied on sys/systm.h,
right before system call definition, as in the rest of the kernel source.
In kern_prot.c, instead of using the dummy structure "args", create
individual dummy structures named <syscall>_args. This makes
life easier for prototype generation.
- Delete redundant declarations.
- Add -Wredundant-declarations to Makefile.i386 so they don't come back.
- Delete sloppy COMMON-style declarations of uninitialized data in
header files.
- Add a few prototypes.
- Clean up warnings resulting from the above.
NB: ioconf.c will still generate a redundant-declaration warning, which
is unavoidable unless somebody volunteers to make `config' smarter.
charge scheduling CPU of child process to the parent and have child
inherit scheduling CPU from parent on fork. Makes a **big** difference
in the feel of the system to interactive users.
Submitted by: John Dyson
