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.
on for a while:
- fine grained TLB shootdown for SMP on i386
- ranged TLB shootdowns.. eg: specify a range of pages to shoot down with
a single IPI, since the IPI is very expensive. Adjust some callers
that used to trigger this inside tight loops to do a ranged shootdown
at the end instead.
- PG_G support for SMP on i386 (options ENABLE_PG_G)
- defer PG_G activation till after we decide what we are going to do with
PSE and the 4MB pages at the start of the kernel. This should solve
some rumored strangeness about stale PG_G entries getting stuck
underneath the 4MB pages.
- add some instrumentation for the fine TLB shootdown
- convert some asm instruction wrappers from functions to inlines. gcc
seems to do a fair bit better with this.
- [temporarily!] pessimize the tlb shootdown IPI handlers. I will fix
this again shortly.
This has been working fairly well for me for a while, but I have tweaked
it again prior to commit since my last major testing round. The only
outstanding problem that I know of is PG_G related, which is why there
is an option for it (not on by default for SMP). I have seen a world
speedups by a few percent (as much as 4 or 5% in one case) but I have
*not* accurately measured this - I am a bit sceptical of these numbers.
New locks are:
- pgrpsess_lock which locks the whole pgrps and sessions,
- pg_mtx which protects the pgrp members, and
- s_mtx which protects the session members.
Please refer to sys/proc.h for the coverage of these locks.
Changes on the pgrp/session interface:
- pgfind() needs the pgrpsess_lock held.
- The caller of enterpgrp() is responsible to allocate a new pgrp and
session.
- Call enterthispgrp() in order to enter an existing pgrp.
- pgsignal() requires a pgrp lock held.
Reviewed by: jhb, alfred
Tested on: cvsup.jp.FreeBSD.org
(which is a quad-CPU machine running -current)
While in userland, keep the thread's ucred reference in a shadow
field so that the usual place to store it is NULL.
If DIAGNOSTIC is not set, the thread ucred is kept valid until the next
kernel entry, at which time it is checked against the process cred
and possibly corrected. Produces a BIG speedup in
kernels with INVARIANTS set. (A previous commit corrected it
for the non INVARIANTS case already)
Reviewed by: dillon@freebsd.org
deprecated in favor of the POSIX-defined lowercase variants.
o Change all occurrences of NTOHL() and associated marcros in the
source tree to use the lowercase function variants.
o Add missing license bits to sparc64's <machine/endian.h>.
Approved by: jake
o Clean up <machine/endian.h> files.
o Remove unused __uint16_swap_uint32() from i386's <machine/endian.h>.
o Remove prototypes for non-existent bswapXX() functions.
o Include <machine/endian.h> in <arpa/inet.h> to define the
POSIX-required ntohl() family of functions.
o Do similar things to expose the ntohl() family in libstand, <netinet/in.h>,
and <sys/param.h>.
o Prepend underscores to the ntohl() family to help deal with
complexities associated with having MD (asm and inline) versions, and
having to prevent exposure of these functions in other headers that
happen to make use of endian-specific defines.
o Create weak aliases to the canonical function name to help deal with
third-party software forgetting to include an appropriate header.
o Remove some now unneeded pollution from <sys/types.h>.
o Add missing <arpa/inet.h> includes in userland.
Tested on: alpha, i386
Reviewed by: bde, jake, tmm
ucontext_t. Forward declare struct __ucontext in <sys/signal.h> and
remove reliance on <sys/ucontext.h> being included.
While I'm here, also hide osigcontext types from userland; suggested
by bde.
Namespace pollution noticed by: Kevin Day <toasty@shell.dragondata.com>
reaquiring it. In the same vein, don't bother dropping the thread cred
when goinf ot userland. We are guaranteed to nned it when we come back,
(which we are guaranteed to do).
Reviewed by: jhb@freebsd.org, bde@freebsd.org (slightly different version)
the structure definitions come from NetBSD to make it easier to share card
definitions. The driver only acts as a shim between the pci bus and the
sio driver. Later pci parallel ports could also be supported through this
driver. Support for most single and multiport pci serial cards should be
as simple as adding its definition to pucdata.c
Tested with the following pci cards:
Moxa Industio CP-114, 4 port RS-232,RS-422/485
Syba Tech Ltd. PCI-4S2P-550-ECP, 4 port RS-232 + 2 parallel ports
Netmos NM9835 PCI-2S-550, 2 port RS-232
patch from a year ago: give file flags their own type. This does not
(yet) change the type used by system calls or library functions.
The underlying type was chosen to match what is returned by stat().
ACPI_NO_SEMAPHORES, ASR_MEASURE_PERFORMANCE, AST_DEBUG, ATAPI_DEBUG,
ATA_DEBUG, BKTR_ALLOC_PAGES, BROOKTREE_ALLOC_PAGES, CAPABILITIES,
COMPAT_SUNOS, CV_DEBUG, MAXFILES, METEOR_TEST_VIDEO, NDEVFSINO,
NDEVFSOVERFLOW, NETGRAPH_BRIDGE, NETSMB, NETSMBCRYPTO, PFIL_HOOKS,
SIMOS, SMBFS, VESA_DEBUG, VGA_DEBUG.
Start using #! to comment out negative options and ## to comment out
broken options.
atapi-all.c:
Fixed rotted bits that were hiding under ATAPI_DEBUG.
atapi-cd.c:
#include "opt_ata.h" so that ACD_DEBUG is actually visible.
ata/atapi-tape.c
#include "opt_ata.h" so that AST_DEBUG is actually visible.
SMP we'd like as much feedback as possible from users about possible
locking problems as early as possible.
To negate most of the performance impact I've also enabled
WITNESS_SKIPSPIN. I've done this as we've been running WITNESS
over the spinlock code for a while without incident and it goes a
long way to making the performance problems of WITNESS much more
bearable.
Users who should be running current should know about turning WITNESS
off for performance reasons.
That said and done, WITNESS could/should be made into a tuneable,
but we'll leave that as an excersize to those that want to disable
it without a kernel recompile.
descriptors. This simplifies code for jumbo frames.
- Cleaned up coding conventions to make code more unix-like.
- Cleaned up code in if_em_fxhw.c and if_em_phy.c.
Added relevant comments.
MFC after: 1 week
slower, and may be impeding adoption of -CURRENT by developers. We
recommend turning on WITNESS by default on crash boxes, and when doing
locking development. It will probably get turned on by default for a week
or two following any major locking commits, also.
Approved by: all and sundry (jhb, phk, ...)
feature bit on newer Athlon CPUs if the BIOS has forgotten to enable
it.
This patch was constructed using some info made available by John
Clemens at http://www.deater.net/john/PavilionN5430.html
Reviewed by: -audit
MFC after: 3 weeks
- Collected i486 identification codes in one place like
586 and 686.
- Merged two cases (0x470 and 0x490) for `Enhanced Am486DX4
Write-Back.'
- Replaced `unknown' into `Unknown'.
Submitted by: chi@bd.mbn.or.jp (Chiharu Shibata)
this is a low-functionality change that changes the kernel to access the main
thread of a process via the linked list of threads rather than
assuming that it is embedded in the process. It IS still embeded there
but remove all teh code that assumes that in preparation for the next commit
which will actually move it out.
Reviewed by: peter@freebsd.org, gallatin@cs.duke.edu, benno rice,
from old signal handlers. This is simpler and faster, and fixes (new)
sigreturn(2) when %eip in the new signal context happens to match the
magic value (0x1d516). 0x1d516 is below the default ELF text section,
so this probably never broken anything in practice.
locore.s:
In addition, don't build the signal trampoline for old signal handlers
when it is not used.
alpha:
Not fixed, but seems to be even less broken in practice due to more
advanced magic. A false match occurs for register #32 in mc_regs[].
Since there is no hardware register #32, a false match is only possible
for direct calls to sigreturn(2) that happen to have the magic number
in the spare mc_regs[32] field.
some arches and the syscall table is machine-independent. It was
(bogusly) conditional on COMPAT_43, so this usually makes no difference.
ia64: in addition:
- replace the bogus cloned comment before osigreturn() by a correct one.
osigreturn() is just a stub fo ia64's.
- fix the formatting of cloned comment before sigreturn().
- fix the return code. use nosys() instead of returning ENOSYS to get
the same semantics as if the syscall is not in the syscall table.
Generating SIGSYS is actually correct here.
- fix style bugs.
powerpc: copy the cleaned up ia64 stub. This mainly fixes a bogus comment.
sparc64: copy the cleaned up the ia64 stub, since there was no stub before.
for SMP in the plain profiling case. It seems to work too.
This error was not detected by LINT because LINT only compiles the
GUPROF profiling case, which is is a superset of the plain profiling
case for !SMP but which is so broken for SMP that the buggy code is
not compiled.
the packet transfer routines, since rev.1.468 of machdep.c does this
better. I'm surprised that disabling interrupts helped much. Disabling
them in the packet receive routine is too late.
Fixed some minor style bugs in rev.1.14.
to fetch the magic word instead of useracc() plus a direct access.
This is more efficient as well as simpler and less incorrect:
- it was inefficent because useracc() takes much longer than just
accessing the data using a correct access method, at least on i386's.
- it was incorrect because direct access is incorrect unless the address
has been mapped. This and nearby direct accesses are mostly handled
better for other arches because they have to be (direct accesses don't
work).
- using magic in sigreturn is still fundamentally broken because false
matches are possible. On i386's, a false match occurs when %eip in a
new signal context happens to equal the magic value. This is not
handled better for other arches.
is not configured. Including <isa/isavar.h> when it is not used is
harmful as well as bogus, since it includes "isa_if.h" which is not
generated when isa is not configured.
This was fixed in 1999 but was broken by unconditionalizing PNPBIOS.
prior ICP Vortex models. This driver was developed by Achim Leubner
of Intel (previously with ICP Vortex) and Boji Kannanthanam of Intel.
Submitted by: "Kannanthanam, Boji T" <boji.t.kannanthanam@intel.com>
MFC after: 2 weeks
This typo keeps us from properly routing an interrupt for CardBus
bridges on this machine. So, now we look for $PIR and then _PIR to
cope. With these changes, the Libretto L1 now works properly.
Evidentally, the idea comes from patch that the Japanese version of
RedHat (or against a Japanese version of Red Hat), but my Japanese
isn't good enough to to know for sure.
Reported by: Hiroyuki Aizu-san <eyes@navi.org>
# This may be an MFC candidate, but I'm not yet sure.
cpuid with %eax=1 will return a logical cpu count in bits 16-23 of %ebx.
Bit 29 is actually 'TM' according to AP-485. This signifies the presence
of the thermal control circuit (which I believe can slow the clock down
to reduce core temperature).
they make it through to userland. This should fix the p5-smp problem
without affecting the other cpus (eg: cyrix, see initcpu.c and the special
cache handling for these cpu types).
Seigo Tanimura (tanimura) posted the initial delta.
I've polished it quite a bit reducing the need for locking and
adapting it for KSE.
Locks:
1 mutex in each filedesc
protects all the fields.
protects "struct file" initialization, while a struct file
is being changed from &badfileops -> &pipeops or something
the filedesc should be locked.
1 mutex in each struct file
protects the refcount fields.
doesn't protect anything else.
the flags used for garbage collection have been moved to
f_gcflag which was the FILLER short, this doesn't need
locking because the garbage collection is a single threaded
container.
could likely be made to use a pool mutex.
1 sx lock for the global filelist.
struct file * fhold(struct file *fp);
/* increments reference count on a file */
struct file * fhold_locked(struct file *fp);
/* like fhold but expects file to locked */
struct file * ffind_hold(struct thread *, int fd);
/* finds the struct file in thread, adds one reference and
returns it unlocked */
struct file * ffind_lock(struct thread *, int fd);
/* ffind_hold, but returns file locked */
I still have to smp-safe the fget cruft, I'll get to that asap.
traps on the first instruction of signal handlers.
In trap.c:syscall(), fake a trace trap if the single-step flag was set
on entry to the kernel, not if it will be set on exit from the kernel.
This fixes bogus trace traps after the last instruction of signal handlers.
gdb-4.18 (the version in FreeBSD) still has problems with the program in
the PR. These seem to be due to bugs in gdb and not in FreeBSD, and are
fixed in gdb-5.1 (the distribution version).
PR: 33262
Tested by: k Macy <kip_macy@yahoo.com>
MFC after: 1 day
whether the machine context is valid and whether the FPU state is
valid (saved).
Mark the machine context valid before copying it out when sending a
signal.
Approved by: -arch
mutex releases to not require flags for the cases when preemption is
not allowed:
The purpose of the MTX_NOSWITCH and SWI_NOSWITCH flags is to prevent
switching to a higher priority thread on mutex releease and swi schedule,
respectively when that switch is not safe. Now that the critical section
API maintains a per-thread nesting count, the kernel can easily check
whether or not it should switch without relying on flags from the
programmer. This fixes a few bugs in that all current callers of
swi_sched() used SWI_NOSWITCH, when in fact, only the ones called from
fast interrupt handlers and the swi_sched of softclock needed this flag.
Note that to ensure that swi_sched()'s in clock and fast interrupt
handlers do not switch, these handlers have to be explicitly wrapped
in critical_enter/exit pairs. Presently, just wrapping the handlers is
sufficient, but in the future with the fully preemptive kernel, the
interrupt must be EOI'd before critical_exit() is called. (critical_exit()
can switch due to a deferred preemption in a fully preemptive kernel.)
I've tested the changes to the interrupt code on i386 and alpha. I have
not tested ia64, but the interrupt code is almost identical to the alpha
code, so I expect it will work fine. PowerPC and ARM do not yet have
interrupt code in the tree so they shouldn't be broken. Sparc64 is
broken, but that's been ok'd by jake and tmm who will be fixing the
interrupt code for sparc64 shortly.
Reviewed by: peter
Tested on: i386, alpha
they were right. Fix both kenter() and kremove() for SMP by ensuring that
the tlb is flushed on other cpu's. This will directly solve random-corruption
panic issues in -stable when it is MFC'd. Better to be safe then sorry, we
can optimize this later.
Original Suspicion by: peter
Maybe MFC: immediately on re's permission
and it's associated state variables: icu_lock with the name "icu". This
renames the imen_mtx for x86 SMP, but also uses the lock to protect
access to the 8259 PIC on x86 UP. This also adds an appropriate lock to
the various Alpha chipsets which fixes problems with Alpha SMP machines
dropping interrupts with an SMP kernel.
for this file, but here goes nothing. This was my first attempt at
tidying up this file. Unfortunately, it just exposes many more horrors
in the code itself that had been masked by the eyesore that was there
before. I think this just needs to be put out of its misery.
