Commit Graph

56 Commits

Author SHA1 Message Date
David Xu
f71ba3d4a7 Remove pcb_switchout, it has not been used for a long time. 2005-12-29 13:23:48 +00:00
Peter Wemm
d1734bad0a It seems I introduced a new prerequisite for <machine/pcb.h> on i386,
which is included from <sys/user.h>.  Add a bandaid for userland.
2005-04-14 04:13:27 +00:00
Peter Wemm
e0ab2c6d10 Change the segment limits to 4GB, we set the user accessible bit on all
of the kernel address space already.  Intel recommend this anyway, because
using a non-4GB limit adds an additional clock cycle to address generation.
We were able to install 4GB segments into the LDT, so any limits we imposed
on %cs and %ds were academic anyway.  More importantly, this allows us to
make a page in the kernel readable to user applications, for holding things
like the signal trampoline and other fun things.

Move the user %cs/%ds segments from the LDT to the GDT.  There was no good
reason for them to be there anyway.  The old LDT entries are still there
but we can now relax the restriction that prevented users from emptying
the default LDT entries.

Putting user and kernel %cs and %ds together allows us to access the fast
sysenter/sysexit/syscall/sysret instructions.  syscall/sysret in particular
require that the user/kernel segments be laid out this way.  Reserve a slot
specifically for NDIS while here.

Create two user controllable slots in the GDT that are context switched
with the (kernel) thread.  This allows user applications to set two
user privilige selectors to arbitary values.  Create
i386_set_fsbase(void *base) and friends. (get/set, fs/gs).  For i386,
%gs is used by tls and the thread libraries and this means that user
processes no longer have to have the cost of having a custom LDT, and
we will no longer to do a ldt switch when activating a kthread/ithread in
the usual case any more.

In other words, we can now set the base address for %fs and %gs to arbitary
addresses without the pain of messing with ldt segments.
2005-04-13 22:57:17 +00:00
Peter Wemm
85b23d1138 Fix an evil bug that appeared in September 2003. VM86 bios calls use two
of the __pcb_spare longs.  Except that fields were changed and one of the
spare values was used and the __pcb_spare field was reduced from two to one
long.  Now VM86 bios calls can trash the first 4 bytes of the next page
following the kernel stack/pcb.  This Is Bad(TM).  This bug has been
present in 5.2-release and onwards, and is still in RELENG_5.

Instead of tempting fate and trying to use "spare" fields, explicitly
reserve them.
2005-04-13 18:13:40 +00:00
Marcel Moolenaar
5a39cbaf69 Implement makectx(). The makectx() function is used by KDB to create
a PCB from a trapframe for purposes of unwinding the stack. The PCB
is used as the thread context and all but the thread that entered the
debugger has a valid PCB.
This function can also be used to create a context for the threads
running on the CPUs that have been stopped when the debugger got
entered. This however is not done at the time of this commit.
2004-07-10 19:56:00 +00:00
Warner Losh
f36cfd49ad Remove advertising clause from University of California Regent's
license, per letter dated July 22, 1999 and email from Peter Wemm,
Alan Cox and Robert Watson.

Approved by: core, peter, alc, rwatson
2004-04-07 20:46:16 +00:00
Jeff Roberson
fa3f9daae5 - On my Pentium4-M laptop, invalpg takes ~1100 cycles if the page is found in
the TLB and ~1600 if it is not.  Therefore, it is more effecient to
   invalidate the TLB after operations that use CMAP rather than before.
 - So that the tlb is invalidated prior to switching off of a processor, we
   must change the switchin functions to switchout functions.
 - Remove td_switchout from the thread and move it to the x86 pcb.
 - Move the code that calls switchout into swtch.s.  These changes make this
   optimization truely x86 specific.
2003-09-30 08:11:36 +00:00
David Xu
8c132e9fae 1.Fix smp race between kernel vm86 BIOS calling and userland vm86 mode code,
remove global variable in_vm86call, set vm86 calling flag in PCB flags.

2.Fix vm86 BIOS calling preempted problem by changing vm86_lock mutex type
  from MTX_DEF to MTX_SPIN. vm86pcb is not remembered in thread struct,
  when the thread calling vm86 BIOS is preempted by interrupt thread,
  and later switching back to the thread would cause incorrect context be
  loaded into CPU registers, this leads to kernel crash.
2002-11-07 01:34:23 +00:00
Peter Wemm
af3f249f3a The a.out md_coredump stuff isn't referenced anywhere anymore, and
hasn't been filled in for ages..  Nuked.
2002-10-15 00:02:50 +00:00
Poul-Henning Kamp
c2b6013026 It is too much work convincing lint why we would want empty structures,
so make the non-empty #ifdef lint.
2002-10-01 14:08:08 +00:00
Jonathan Mini
9ba1547929 Add kernel support needed for the KSE-aware libpthread:
- Maintain fpu state across signals.
	- Save and restore FPU state properly in ucontext_t's.

Reviewed by:	deischen, julian
Approved by:	-arch
2002-09-16 19:25:41 +00:00
Matthew Dillon
d74ac6819b Compromise for critical*()/cpu_critical*() recommit. Cleanup the interrupt
disablement assumptions in kern_fork.c by adding another API call,
cpu_critical_fork_exit().  Cleanup the td_savecrit field by moving it
from MI to MD.  Temporarily move cpu_critical*() from <arch>/include/cpufunc.h
to <arch>/<arch>/critical.c (stage-2 will clean this up).

Implement interrupt deferral for i386 that allows interrupts to remain
enabled inside critical sections.  This also fixes an IPI interlock bug,
and requires uses of icu_lock to be enclosed in a true interrupt disablement.

This is the stage-1 commit.  Stage-2 will occur after stage-1 has stabilized,
and will move cpu_critical*() into its own header file(s) + other things.
This commit may break non-i386 architectures in trivial ways.  This should
be temporary.

Reviewed by:	core
Approved by:	core
2002-03-27 05:39:23 +00:00
Alfred Perlstein
b63dc6ad47 Remove __P. 2002-03-20 05:48:58 +00:00
Matthew Dillon
181df8c9d4 revert last commit temporarily due to whining on the lists. 2002-02-26 20:33:41 +00:00
Matthew Dillon
f96ad4c223 STAGE-1 of 3 commit - allow (but do not require) interrupts to remain
enabled in critical sections and streamline critical_enter() and
critical_exit().

This commit allows an architecture to leave interrupts enabled inside
critical sections if it so wishes.  Architectures that do not wish to do
this are not effected by this change.

This commit implements the feature for the I386 architecture and provides
a sysctl, debug.critical_mode, which defaults to 1 (use the feature).  For
now you can turn the sysctl on and off at any time in order to test the
architectural changes or track down bugs.

This commit is just the first stage.  Some areas of the code, specifically
the MACHINE_CRITICAL_ENTER #ifdef'd code, is strictly temporary and will
be cleaned up in the STAGE-2 commit when the critical_*() functions are
moved entirely into MD files.

The following changes have been made:

	* critical_enter() and critical_exit() for I386 now simply increment
	  and decrement curthread->td_critnest.  They no longer disable
	  hard interrupts.  When critical_exit() decrements the counter to
	  0 it effectively calls a routine to deal with whatever interrupts
	  were deferred during the time the code was operating in a critical
	  section.

	  Other architectures are unaffected.

	* fork_exit() has been conditionalized to remove MD assumptions for
	  the new code.  Old code will still use the old MD assumptions
	  in regards to hard interrupt disablement.  In STAGE-2 this will
	  be turned into a subroutine call into MD code rather then hardcoded
	  in MI code.

	  The new code places the burden of entering the critical section
	  in the trampoline code where it belongs.

	* I386: interrupts are now enabled while we are in a critical section.
	  The interrupt vector code has been adjusted to deal with the fact.
	  If it detects that we are in a critical section it currently defers
	  the interrupt by adding the appropriate bit to an interrupt mask.

	* In order to accomplish the deferral, icu_lock is required.  This
	  is i386-specific.  Thus icu_lock can only be obtained by mainline
	  i386 code while interrupts are hard disabled.  This change has been
	  made.

	* Because interrupts may or may not be hard disabled during a
	  context switch, cpu_switch() can no longer simply assume that
	  PSL_I will be in a consistent state.  Therefore, it now saves and
	  restores eflags.

	* FAST INTERRUPT PROVISION.  Fast interrupts are currently deferred.
	  The intention is to eventually allow them to operate either while
	  we are in a critical section or, if we are able to restrict the
	  use of sched_lock, while we are not holding the sched_lock.

	* ICU and APIC vector assembly for I386 cleaned up.  The ICU code
	  has been cleaned up to match the APIC code in regards to format
	  and macro availability.  Additionally, the code has been adjusted
	  to deal with deferred interrupts.

	* Deferred interrupts use a per-cpu boolean int_pending, and
	  masks ipending, spending, and fpending.  Being per-cpu variables
	  it is not currently necessary to lock; bus cycles modifying them.

	  Note that the same mechanism will enable preemption to be
	  incorporated as a true software interrupt without having to
	  further hack up the critical nesting code.

	* Note: the old critical_enter() code in kern/kern_switch.c is
	  currently #ifdef to be compatible with both the old and new
	  methodology.  In STAGE-2 it will be moved entirely to MD code.

Performance issues:

	One of the purposes of this commit is to enhance critical section
	performance, specifically to greatly reduce bus overhead to allow
	the critical section code to be used to protect per-cpu caches.
	These caches, such as Jeff's slab allocator work, can potentially
	operate very quickly making the effective savings of the new
	critical section code's performance very significant.

	The second purpose of this commit is to allow architectures to
	enable certain interrupts while in a critical section.  Specifically,
	the intention is to eventually allow certain FAST interrupts to
	operate rather then defer.

	The third purpose of this commit is to begin to clean up the
	critical_enter()/critical_exit()/cpu_critical_enter()/
	cpu_critical_exit() API which currently has serious cross pollution
	in MI code (in fork_exit() and ast() for example).

	The fourth purpose of this commit is to provide a framework that
	allows kernel-preempting software interrupts to be implemented
	cleanly.  This is currently used for two forward interrupts in I386.
	Other architectures will have the choice of using this infrastructure
	or building the functionality directly into critical_enter()/
	critical_exit().

	Finally, this commit is designed to greatly improve the flexibility
	of various architectures to manage critical section handling,
	software interrupts, preemption, and other highly integrated
	architecture-specific details.
2002-02-26 17:06:21 +00:00
Bruce Evans
e744f30933 Changed the type of pcb_flags from u_char to u_int and adjusted things.
This removes the only atomic operation on a char type in the entire
kernel.
2002-01-17 17:49:23 +00:00
John Baldwin
24db04598b Split the per-process Local Descriptor Table out of the PCB and into
struct mdproc.

Submitted by:	Andrew R. Reiter <arr@watson.org>
Silence on:	-current
2001-10-25 00:53:43 +00:00
Peter Wemm
28f74b2003 The #define for pcb_savefpu seems to do more harm than good. 2001-07-12 12:48:08 +00:00
Peter Wemm
9d146ac5d1 Activate SSE/SIMD. This is the extra context switching support that
we are required to do if we let user processes use the extra 128 bit
registers etc.

This is the base part of the diff I got from:
  http://www.issei.org/issei/FreeBSD/sse.html
I believe this is by:  Mr. SUZUKI Issei <issei@issei.org>
SMP support apparently by: Takekazu KATO <kato@chino.it.okayama-u.ac.jp>
Test code by: NAKAMURA Kazushi <kaz@kobe1995.net>, see
  http://kobe1995.net/~kaz/FreeBSD/SSE.en.html

I have fixed a couple of style(9) deviations.  I have some followup
commits to fix a couple of non-style things.
2001-07-12 06:32:51 +00:00
Bruce Evans
1c1771cb5b Convert npx interrupts into traps instead of vice versa. This is much
simpler for npx exceptions that start as traps (no assembly required...)
and works better for npx exceptions that start as interrupts (there is
no longer a problem for nested interrupts).

Submitted by:	original (pre-SMPng) version by luoqi
2001-05-22 21:20:49 +00:00
Peter Wemm
f1532aadee Activate USER_LDT by default. The new thread libraries are going to
depend on this.  The linux ABI emulator tries to use it for some linux
binaries too.  VM86 had a bigger cost than this and it was made default
a while ago.

Reviewed by:	jhb, imp
2001-02-23 01:25:02 +00:00
John Baldwin
5813dc03bd - Don't call clear_resched() in userret(), instead, clear the resched flag
in mi_switch() just before calling cpu_switch() so that the first switch
  after a resched request will satisfy the request.
- While I'm at it, move a few things into mi_switch() and out of
  cpu_switch(), specifically set the p_oncpu and p_lastcpu members of
  proc in mi_switch(), and handle the sched_lock state change across a
  context switch in mi_switch().
- Since cpu_switch() no longer handles the sched_lock state change, we
  have to setup an initial state for sched_lock in fork_exit() before we
  release it.
2001-02-20 05:26:15 +00:00
Bruce Evans
4a3bb59944 Declare or #define per-cpu globals in <machine/globals.h> in all cases.
The i386 UP case was messily different.
2000-10-27 08:30:59 +00:00
Jason Evans
0384fff8c5 Major update to the way synchronization is done in the kernel. Highlights
include:

* Mutual exclusion is used instead of spl*().  See mutex(9).  (Note: The
  alpha port is still in transition and currently uses both.)

* Per-CPU idle processes.

* Interrupts are run in their own separate kernel threads and can be
  preempted (i386 only).

Partially contributed by:	BSDi (BSD/OS)
Submissions by (at least):	cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
Peter Wemm
664a31e496 Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL"
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot).  This is consistant with the other
BSD's who made this change quite some time ago.  More commits to come.
1999-12-29 04:46:21 +00:00
Luoqi Chen
91c28bfde0 User ldt sharing. 1999-12-06 04:53:08 +00:00
Peter Wemm
c3aac50f28 $Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00
Jonathan Lemon
ab001a72be Implement support for hardware debug registers on the i386.
Submitted by:	Brian Dean <brdean@unx.sas.com>
1999-07-09 04:16:00 +00:00
Jonathan Lemon
eb9d435ae7 Unifdef VM86.
Reviewed by:	silence on on -current
1999-06-01 18:20:36 +00:00
Luoqi Chen
5206bca10a Enable vmspace sharing on SMP. Major changes are,
- %fs register is added to trapframe and saved/restored upon kernel entry/exit.
- Per-cpu pages are no longer mapped at the same virtual address.
- Each cpu now has a separate gdt selector table. A new segment selector
  is added to point to per-cpu pages, per-cpu global variables are now
  accessed through this new selector (%fs). The selectors in gdt table are
  rearranged for cache line optimization.
- fask_vfork is now on as default for both UP and SMP.
- Some aio code cleanup.

Reviewed by:	Alan Cox	<alc@cs.rice.edu>
		John Dyson	<dyson@iquest.net>
		Julian Elischer	<julian@whistel.com>
		Bruce Evans	<bde@zeta.org.au>
		David Greenman	<dg@root.com>
1999-04-28 01:04:33 +00:00
Bruce Evans
a8961a8284 Ifdefed some SMP and VM86 code. Note that although VM86 is not a global
option, the ifdef on it in a header works because only the name of the
VM86 extension is hidden.
1998-02-03 21:27:50 +00:00
Peter Wemm
b54470b433 Don't #include unneeded includes here. pcb_ext.h picks up lots of other
stuff with it.
1997-10-10 12:40:09 +00:00
John Dyson
48a09cf276 VM86 kernel support.
Work done by BSDI, Jonathan Lemon <jlemon@americantv.com>,
	Mike Smith <msmith@gsoft.com.au>, Sean Eric Fagan <sef@kithrup.com>,
	and probably alot of others.
Submitted by:	Jnathan Lemon <jlemon@americantv.com>
1997-08-09 00:04:06 +00:00
Peter Wemm
b3196e4b9f Preliminary support for per-cpu data pages.
This eliminates a lot of #ifdef SMP type code.  Things like _curproc reside
in a data page that is unique on each cpu, eliminating the expensive macros
like:    #define curproc (SMPcurproc[cpunumber()])

There are some unresolved bootstrap and address space sharing issues at
present, but Steve is waiting on this for other work.  There is still some
strictly temporary code present that isn't exactly pretty.

This is part of a larger change that has run into some bumps, this part is
standalone so it should be safe.  The temporary code goes away when the
full idle cpu support is finished.

Reviewed by: fsmp, dyson
1997-06-22 16:04:22 +00:00
Bruce Evans
7b3c84247b Preserve %fs and %gs across context switches. This has a relatively low
cost since it is only done in cpu_switch(), not for every exception.
The extra state is kept in the pcb, and handled much like the npx state,
with similar deficiencies (the state is not preserved across signal
handlers, and error handling loses state).
1997-06-07 04:36:10 +00:00
Peter Wemm
503c887bae remove #include opt_smp.h
declare SMPcurpcb[] next to #define and uniprocessor counterpart
1997-05-07 19:49:32 +00:00
Peter Wemm
477a642cee Man the liferafts! Here comes the long awaited SMP -> -current merge!
There are various options documented in i386/conf/LINT, there is more to
come over the next few days.

The kernel should run pretty much "as before" without the options to
activate SMP mode.

There are a handful of known "loose ends" that need to be fixed, but
have been put off since the SMP kernel is in a moderately good condition
at the moment.

This commit is the result of the tinkering and testing over the last 14
months by many people.  A special thanks to Steve Passe for implementing
the APIC code!
1997-04-26 11:46:25 +00:00
Peter Wemm
271b264e4c No longer use an i386tss as the basis of our pcb - it wasn't particularly
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
1997-04-07 06:45:18 +00:00
Peter Wemm
6875d25465 Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.
1997-02-22 09:48:43 +00:00
Jordan K. Hubbard
1130b656e5 Make the long-awaited change from $Id$ to $FreeBSD$
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.
1997-01-14 07:20:47 +00:00
Bruce Evans
85acc6887d Eliminated pcb_inl. It was always 0 because context switches don't occur
in interrupt handlers.
1996-07-31 12:36:11 +00:00
Bruce Evans
eabe0f9f57 Don't return unused values in cpu_switch() or savectx().
Don't preserve unused registers in the NPX case in savectx().
1996-05-01 03:47:04 +00:00
Poul-Henning Kamp
68832d3037 Fix cpu_fork for real.
Suggested by:	 bde
1996-04-25 06:20:19 +00:00
Poul-Henning Kamp
6f1e6c97de savectx returns through cpu_switch in case of the child, so it must
return void just like cpu_switch.  Fix prototype and usage from machdep.c
1996-04-19 07:28:04 +00:00
Poul-Henning Kamp
7d2392141d Fix a bogon. cpu_fork & savectx ecpected cpu_switch to restore %eax,
they shouldn't.
1996-04-18 21:34:53 +00:00
Peter Wemm
d66a506616 Mega-commit for Linux emulator update.. This has been stress tested under
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.
1996-03-02 19:38:20 +00:00
David Greenman
2924d49169 Simplified savectx() a little and fixed a bug that caused it to return
garbage in the child process rather than "1" like it is supposed to.

Reviewed by:	bde
1996-01-23 02:39:24 +00:00
David Greenman
d0d1c65888 Killed some unused stuff inherited from Bill Jolitz. Note that since
this changes the size of the pcb struct, gdb will need to be rebuilt
or debugging won't work correctly.

Reviewed by:	Bruce Evans
1995-08-17 11:30:03 +00:00
Bruce Evans
b39b673d37 i386/exception.s,
Keep track of interrupt nesting level.  It is normally 0
	for syscalls and traps, but is fudged to 1 for their exit
	processing in case they metamorphose into an interrupt
	handler.

i386/genassym.c;
	Remove support for the obsolete pcb_iml and pcb_cmap2.

	Add support for pcb_inl.

i386/swtch.s:
	Fudge the interrupt nesting level across context switches and in
	the idle loop so that the work for preemptive context switches
	gets counted as interrupt time, the work for voluntary context
	switches gets counted mostly as system time (the part when
	curproc == 0 gets counted as interrupt time), and only truly idle
	time gets counted as idle time.

	Remove obsolete support (commented out and otherwise) for pcb_iml.

	Load curpcb just before curproc instead of just after so that
	curpcb is always valid if curproc is.  A few more changes like
	this may fix tracing through context switches.

	Remove obsolete function swtch_to_inactive().

include/cpu.h:
	Use the new interrupt nesting level variable to implement a
	non-fake CLF_INTR() so that accounting for the interrupt state
	works.

	You can use top, iostat or (best) an up to date systat to see
	interrupt overheads.  I see the expected huge interrupt overheads
	for ISA devices (on a 486DX/33, about 55% for an IDE drive
	transferring 1250K/sec and the same for a WD8013EBT network card
	transferring 1100K/sec).  The huge interrupt overheads for serial
	devices are unfortunately normally invisible.

include/pcb.h:
	Remove the obsolete pcb_iml and pcb_cmap2.  Replace them by
	padding to preserve binary compatibility.

	Use part of the new padding for pcb_inl.

isa/icu.s:
isa/vector.s:
	Keep track of interrupt nesting level.
1994-12-03 10:03:19 +00:00
Poul-Henning Kamp
50a1a05445 Added prototypes. 1994-10-08 22:21:34 +00:00