code in sys/kern/kern_dump.c. Most dumpsys() implementations are nearly
identical and simply redefine a number of constants and helper subroutines;
a generic implementation will make it easier to implement features around
kernel core dumps. This change does not alter any minidump code and should
have no functional impact.
PR: 193873
Differential Revision: https://reviews.freebsd.org/D904
Submitted by: Conrad Meyer <conrad.meyer@isilon.com>
Reviewed by: jhibbits (earlier version)
Sponsored by: EMC / Isilon Storage Division
was possible for a regular user to setup the dump device if he had write access
to the given device. In theory it is a security issue as user might get access
to kernel's memory after provoking kernel crash, but in practise it is not
recommended to give regular users direct access to storage devices.
Rework the code so that we do privileges check within the set_dumper() function
to avoid similar problems in the future.
Discussed with: secteam
This commit does not add error returns to minidumpsys() or
textdump_dumpsys(); those can also be added later.
Submitted by: Conrad Meyer (EMC / Isilon storage division)
These changes prevent sysctl(8) from returning proper output,
such as:
1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.
Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.
MFC after: 2 weeks
Sponsored by: Mellanox Technologies
Right now, init(8) cannot distinguish between an ACPI power button press
or a Ctrl+Alt+Del sequence on the keyboard. This is because
shutdown_nice() sends SIGINT to init(8) unconditionally, but later
modifies the arguments to reboot(2) to force a certain behaviour.
Instead of doing this, patch up the code to just forward the appropriate
signal to userspace. SIGUSR1 and SIGUSR2 can already be used to halt the
system.
While there, move waittime to the function where it's used; kern_reboot().
defaults to PANIC_REBOOT_WAIT_TIME (a long-existing kernel config
setting). Use this now-variable value in place of the defined constant
to control how long the system waits after a panic before rebooting.
future further optimizations where the vm_object lock will be held
in read mode most of the time the page cache resident pool of pages
are accessed for reading purposes.
The change is mostly mechanical but few notes are reported:
* The KPI changes as follow:
- VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK()
- VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK()
- VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK()
- VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED()
(in order to avoid visibility of implementation details)
- The read-mode operations are added:
VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(),
VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED()
* The vm/vm_pager.h namespace pollution avoidance (forcing requiring
sys/mutex.h in consumers directly to cater its inlining functions
using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h
consumers now must include also sys/rwlock.h.
* zfs requires a quite convoluted fix to include FreeBSD rwlocks into
the compat layer because the name clash between FreeBSD and solaris
versions must be avoided.
At this purpose zfs redefines the vm_object locking functions
directly, isolating the FreeBSD components in specific compat stubs.
The KPI results heavilly broken by this commit. Thirdy part ports must
be updated accordingly (I can think off-hand of VirtualBox, for example).
Sponsored by: EMC / Isilon storage division
Reviewed by: jeff
Reviewed by: pjd (ZFS specific review)
Discussed with: alc
Tested by: pho
This is an ongoing effort to provide runtime debug information
useful in the field that does not panic existing installations.
This gives us the flexibility needed when shipping images to a
potentially large audience with WITNESS enabled without worrying
about formerly non-fatal LORs hurting a release.
Sponsored by: iXsystems
This is to allow debug images to be used without taking down the
system when non-fatal asserts are hit.
The following sysctls are added:
debug.kassert.warn_only: 1 = log, 0 = panic
debug.kassert.do_ktr: set to a ktr mask for logging via KTR
debug.kassert.do_log: 1 = log, 0 = quiet
debug.kassert.warnings: stats, number of kasserts hit
debug.kassert.log_panic_at:
number of kasserts before we actually panic, 0 = never
debug.kassert.log_pps_limit: pps limit for log messages
debug.kassert.log_mute_at: stop warning after N kasserts, 0 = never stop
debug.kassert.kassert: set this sysctl to trigger a kassert
Discussed with: scottl, gnn, marcel
Sponsored by: iXsystems
There has not been any complaints about the default behavior, so there
is no need to keep a knob that enables the worse alternative.
Now that the hard-stopping of other CPUs is the only behavior, the panic_cpu
spinlock-like logic can be dropped, because only a single CPU is
supposed to win stop_cpus_hard(other_cpus) race and proceed past that
call.
MFC after: 1 month
this is a VNET-kernel or not. gcc used to put the static symbol into
the symbol table, clang does not. This fixes the 'netstat: no namelist'
error seen on clang+VNET systems.
primitives by breaking stop_scheduler into a per-thread variable.
Also, store the new td_stopsched very close to td_*locks members as
they will be accessed mostly in the same codepaths as td_stopsched and
this results in avoiding a further cache-line pollution, possibly.
STOP_SCHEDULER() was pondered to use a new 'thread' argument, in order to
take advantage of already cached curthread, but in the end there should
not really be a performance benefit, while introducing a KPI breakage.
In collabouration with: flo
Reviewed by: avg
MFC after: 3 months (or never)
X-MFC: r228424
Historical behavior of letting other CPUs merily go on is a default for
time being. The new behavior can be switched on via
kern.stop_scheduler_on_panic tunable and sysctl.
Stopping of the CPUs has (at least) the following benefits:
- more of the system state at panic time is preserved intact
- threads and interrupts do not interfere with dumping of the system
state
Only one thread runs uninterrupted after panic if stop_scheduler_on_panic
is set. That thread might call code that is also used in normal context
and that code might use locks to prevent concurrent execution of certain
parts. Those locks might be held by the stopped threads and would never
be released. To work around this issue, it was decided that instead of
explicit checks for panic context, we would rather put those checks
inside the locking primitives.
This change has substantial portions written and re-written by attilio
and kib at various times. Other changes are heavily based on the ideas
and patches submitted by jhb and mdf. bde has provided many insights
into the details and history of the current code.
The new behavior may cause problems for systems that use a USB keyboard
for interfacing with system console. This is because of some unusual
locking patterns in the ukbd code which have to be used because on one
hand ukbd is below syscons, but on the other hand it has to interface
with other usb code that uses regular mutexes/Giant for its concurrency
protection. Dumping to USB-connected disks may also be affected.
PR: amd64/139614 (at least)
In cooperation with: attilio, jhb, kib, mdf
Discussed with: arch@, bde
Tested by: Eugene Grosbein <eugen@grosbein.net>,
gnn,
Steven Hartland <killing@multiplay.co.uk>,
glebius,
Andrew Boyer <aboyer@averesystems.com>
(various versions of the patch)
MFC after: 3 months (or never)
The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.
Reviewed by: rwatson
Approved by: re (bz)
of the device boundry.
While this is generally ok, the problem is that all the consumers
handle similar cases (and expect to catch) ENOSPC for this (for a
reference look at minidumpsys() and dumpsys() constructions). That
ends up in consumers not recognizing the issue and amd64 failing to
retry if the number of pages grows up during minidump.
Fix this by returning ENOSPC in dump_write() and while here add some
more diagnostic on involved values.
Sponsored by: Sandvine Incorporated
In collabouration with: emaste
Approved by: re (kib)
MFC after: 10 days
- Axe out the SHOW_BUSYBUFS option and uses a tunable for selectively
enable/disable it, which is defaulted for not printing anything (0
value) but can be changed for printing (1 value) and be verbose (2
value)
- Improves the informations outputed: right now, there is no track of
the actual struct buf object or vnode which are referenced by the
shutdown process, but it is printed the related struct bufobj object
which is not really helpful
- Add more verbosity about the state of the struct buf lock and the
vnode informations, with the latter to be activated separately by the
sysctl
Sponsored by: Sandvine Incorporated
Reviewed by: emaste, kib
Approved by: re (ksmith)
MFC after: 10 days
This is done per request/suggestion from John Baldwin
who introduced the option. Trying to resume normal
system operation after a panic is very unpredictable
and dangerous. It will become even more dangerous
when we allow a thread in panic(9) to penetrate all
lock contexts.
I understand that the only purpose of this option was
for testing scenarios potentially resulting in panic.
Suggested by: jhb
Reviewed by: attilio, jhb
X-MFC-After: never
Approved by: re (kib)
interleaving.
Signal dumping to happen only for the first panic which should be the
most important.
Sponsored by: Sandvine Incorporated
Submitted by: Nima Misaghian (nmisaghian AT sandvine DOT com)
MFC after: 2 weeks
for it. Do not not expect a developer to call doadump(). Calling
doadump does not necessarily work when it's declared static. Nor
does it necessarily do what was intended in the context of text
dumps. The dump command always creates a core dump.
Move printing of error messages from doadump to the dump command,
now that we don't have to worry about being called from DDB.
disk dumping.
With the option SW_WATCHDOG on, these operations are doomed to let
watchdog fire, fi they take too long.
I implemented the stubs this way because I really want wdog_kern_*
KPI to not be dependant by SW_WATCHDOG being on (and really, the option
only enables watchdog activation in hardclock) and also avoid to
call them when not necessary (avoiding not-volountary watchdog
activations).
Sponsored by: Sandvine Incorporated
Discussed with: emaste, des
MFC after: 2 weeks
existing code caused problems with some SCSI controllers.
A new sysctl kern.cam.ada.spindown_shutdown has been added that controls
whether or not to spin-down disks when shutting down.
Spinning down the disks unloads/parks the heads - this is
much better than removing power when the disk is still
spinning because otherwise an Emergency Unload occurs which may cause damage
to the actuator.
PR: kern/140752
Submitted by: olli
Reviewed by: arundel
Discussed with: mav
MFC after: 2 weeks
This is to prevent caching of its value in a register when it is checked
and modified by multiple CPUs in parallel.
Also, move the variable into the scope of the only function that uses it.
Reviewed by: jhb
Hint from: mdf
MFC after: 1 week
Keep the interrupts disabled in order to avoid preemption problems.
Reported by: tinderbox, b.f. <bf1783 at googlemail dot com>
MFC: 2 weeks
X-MFC: r206878
When performing a smp_rendezvous() or more likely, on amd64 and i386,
a smp_tlb_shootdown() the caller will end up with the smp_ipi_mtx
spinlock held, busy-waiting for other CPUs to acknowledge the operation.
As long as CPUs are suspended (via cpu_reset()) between the active mask
read and IPI sending there can be a deadlock where the caller will wait
forever for a dead CPU to acknowledge the operation.
Please note that on CPU0 that is going to be someway heavier because of
the spinlocks being disabled earlier than quitting the machine.
Fix this bug by calling cpu_reset() with the smp_ipi_mtx held.
Note that it is very likely that a saner offline/online CPUs mechanism
will help heavilly in fixing similar cases as it is likely more bugs
of this type may arise in the future.
Reported by: rwatson
Discussed with: jhb
Tested by: rnoland, Giovanni Trematerra
<giovanni dot trematerra at gmail dot com>
MFC: 2 weeks
Special deciation to: anyone who made possible to have 16-ways machines
in Netperf
Make CAM to stop all attached devices on system shutdown.
It allows devices to park heads, reducing stress on power loss.
Add `kern.cam.power_down` tunable and sysctl to controll it.
has proven to have a good effect when entering KDB by using a NMI,
but it completely violates all the good rules about interrupts
disabled while holding a spinlock in other occasions. This can be the
cause of deadlocks on events where a normal IPI_STOP is expected.
* Adds an new IPI called IPI_STOP_HARD on all the supported architectures.
This IPI is responsible for sending a stop message among CPUs using a
privileged channel when disponible. In other cases it just does match a
normal IPI_STOP.
Right now the IPI_STOP_HARD functionality uses a NMI on ia32 and amd64
architectures, while on the other has a normal IPI_STOP effect. It is
responsibility of maintainers to eventually implement an hard stop
when necessary and possible.
* Use the new IPI facility in order to implement a new userend SMP kernel
function called stop_cpus_hard(). That is specular to stop_cpu() but
it does use the privileged channel for the stopping facility.
* Let KDB use the newly introduced function stop_cpus_hard() and leave
stop_cpus() for all the other cases
* Disable interrupts on CPU0 when starting the process of APs suspension.
* Style cleanup and comments adding
This patch should fix the reboot/shutdown deadlocks many users are
constantly reporting on mailing lists.
Please don't forget to update your config file with the STOP_NMI
option removal
Reviewed by: jhb
Tested by: pho, bz, rink
Approved by: re (kib)
and used in a large number of files, but also because an increasing number
of incorrect uses of MAC calls were sneaking in due to copy-and-paste of
MAC-aware code without the associated opt_mac.h include.
Discussed with: pjd
The system hostname is now stored in prison0, and the global variable
"hostname" has been removed, as has the hostname_mtx mutex. Jails may
have their own host information, or they may inherit it from the
parent/system. The proper way to read the hostname is via
getcredhostname(), which will copy either the hostname associated with
the passed cred, or the system hostname if you pass NULL. The system
hostname can still be accessed directly (and without locking) at
prison0.pr_host, but that should be avoided where possible.
The "similar information" referred to is domainname, hostid, and
hostuuid, which have also become prison parameters and had their
associated global variables removed.
Approved by: bz (mentor)
on a generic dumper that creates an ELF core file and
uses PMAP functions to scan and iterate over memory
chunks, as well as handle memory mappings used during
dumping.
the PMAP layer can choose to return physical memory
chunks or virtual memory chunks. For minidumps, the
chunks should be virtual.
The default MMU I/F implementation for the scan_md()
method returns NULL. Thus, when a PMAP implementation
does not implement the required methods, an empty
core file is created. Here, empty means having an ELF
header only.
Obtained from: Juniper Networks
