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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/trace/rv/runtime-verification.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
Diffstat (limited to 'Documentation/trace/rv/runtime-verification.rst')
-rw-r--r-- | Documentation/trace/rv/runtime-verification.rst | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/Documentation/trace/rv/runtime-verification.rst b/Documentation/trace/rv/runtime-verification.rst new file mode 100644 index 000000000..c46b61494 --- /dev/null +++ b/Documentation/trace/rv/runtime-verification.rst @@ -0,0 +1,231 @@ +==================== +Runtime Verification +==================== + +Runtime Verification (RV) is a lightweight (yet rigorous) method that +complements classical exhaustive verification techniques (such as *model +checking* and *theorem proving*) with a more practical approach for complex +systems. + +Instead of relying on a fine-grained model of a system (e.g., a +re-implementation a instruction level), RV works by analyzing the trace of the +system's actual execution, comparing it against a formal specification of +the system behavior. + +The main advantage is that RV can give precise information on the runtime +behavior of the monitored system, without the pitfalls of developing models +that require a re-implementation of the entire system in a modeling language. +Moreover, given an efficient monitoring method, it is possible execute an +*online* verification of a system, enabling the *reaction* for unexpected +events, avoiding, for example, the propagation of a failure on safety-critical +systems. + +Runtime Monitors and Reactors +============================= + +A monitor is the central part of the runtime verification of a system. The +monitor stands in between the formal specification of the desired (or +undesired) behavior, and the trace of the actual system. + +In Linux terms, the runtime verification monitors are encapsulated inside the +*RV monitor* abstraction. A *RV monitor* includes a reference model of the +system, a set of instances of the monitor (per-cpu monitor, per-task monitor, +and so on), and the helper functions that glue the monitor to the system via +trace, as depicted bellow:: + + Linux +---- RV Monitor ----------------------------------+ Formal + Realm | | Realm + +-------------------+ +----------------+ +-----------------+ + | Linux kernel | | Monitor | | Reference | + | Tracing | -> | Instance(s) | <- | Model | + | (instrumentation) | | (verification) | | (specification) | + +-------------------+ +----------------+ +-----------------+ + | | | + | V | + | +----------+ | + | | Reaction | | + | +--+--+--+-+ | + | | | | | + | | | +-> trace output ? | + +------------------------|--|----------------------+ + | +----> panic ? + +-------> <user-specified> + +In addition to the verification and monitoring of the system, a monitor can +react to an unexpected event. The forms of reaction can vary from logging the +event occurrence to the enforcement of the correct behavior to the extreme +action of taking a system down to avoid the propagation of a failure. + +In Linux terms, a *reactor* is an reaction method available for *RV monitors*. +By default, all monitors should provide a trace output of their actions, +which is already a reaction. In addition, other reactions will be available +so the user can enable them as needed. + +For further information about the principles of runtime verification and +RV applied to Linux: + + Bartocci, Ezio, et al. *Introduction to runtime verification.* In: Lectures on + Runtime Verification. Springer, Cham, 2018. p. 1-33. + + Falcone, Ylies, et al. *A taxonomy for classifying runtime verification tools.* + In: International Conference on Runtime Verification. Springer, Cham, 2018. p. + 241-262. + + De Oliveira, Daniel Bristot. *Automata-based formal analysis and + verification of the real-time Linux kernel.* Ph.D. Thesis, 2020. + +Online RV monitors +================== + +Monitors can be classified as *offline* and *online* monitors. *Offline* +monitor process the traces generated by a system after the events, generally by +reading the trace execution from a permanent storage system. *Online* monitors +process the trace during the execution of the system. Online monitors are said +to be *synchronous* if the processing of an event is attached to the system +execution, blocking the system during the event monitoring. On the other hand, +an *asynchronous* monitor has its execution detached from the system. Each type +of monitor has a set of advantages. For example, *offline* monitors can be +executed on different machines but require operations to save the log to a +file. In contrast, *synchronous online* method can react at the exact moment +a violation occurs. + +Another important aspect regarding monitors is the overhead associated with the +event analysis. If the system generates events at a frequency higher than the +monitor's ability to process them in the same system, only the *offline* +methods are viable. On the other hand, if the tracing of the events incurs +on higher overhead than the simple handling of an event by a monitor, then a +*synchronous online* monitors will incur on lower overhead. + +Indeed, the research presented in: + + De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo Silva. + *Efficient formal verification for the Linux kernel.* In: International + Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. + p. 315-332. + +Shows that for Deterministic Automata models, the synchronous processing of +events in-kernel causes lower overhead than saving the same events to the trace +buffer, not even considering collecting the trace for user-space analysis. +This motivated the development of an in-kernel interface for online monitors. + +For further information about modeling of Linux kernel behavior using automata, +see: + + De Oliveira, Daniel B.; De Oliveira, Romulo S.; Cucinotta, Tommaso. *A thread + synchronization model for the PREEMPT_RT Linux kernel.* Journal of Systems + Architecture, 2020, 107: 101729. + +The user interface +================== + +The user interface resembles the tracing interface (on purpose). It is +currently at "/sys/kernel/tracing/rv/". + +The following files/folders are currently available: + +**available_monitors** + +- Reading list the available monitors, one per line + +For example:: + + # cat available_monitors + wip + wwnr + +**available_reactors** + +- Reading shows the available reactors, one per line. + +For example:: + + # cat available_reactors + nop + panic + printk + +**enabled_monitors**: + +- Reading lists the enabled monitors, one per line +- Writing to it enables a given monitor +- Writing a monitor name with a '!' prefix disables it +- Truncating the file disables all enabled monitors + +For example:: + + # cat enabled_monitors + # echo wip > enabled_monitors + # echo wwnr >> enabled_monitors + # cat enabled_monitors + wip + wwnr + # echo '!wip' >> enabled_monitors + # cat enabled_monitors + wwnr + # echo > enabled_monitors + # cat enabled_monitors + # + +Note that it is possible to enable more than one monitor concurrently. + +**monitoring_on** + +This is an on/off general switcher for monitoring. It resembles the +"tracing_on" switcher in the trace interface. + +- Writing "0" stops the monitoring +- Writing "1" continues the monitoring +- Reading returns the current status of the monitoring + +Note that it does not disable enabled monitors but stop the per-entity +monitors monitoring the events received from the system. + +**reacting_on** + +- Writing "0" prevents reactions for happening +- Writing "1" enable reactions +- Reading returns the current status of the reaction + +**monitors/** + +Each monitor will have its own directory inside "monitors/". There the +monitor-specific files will be presented. The "monitors/" directory resembles +the "events" directory on tracefs. + +For example:: + + # cd monitors/wip/ + # ls + desc enable + # cat desc + wakeup in preemptive per-cpu testing monitor. + # cat enable + 0 + +**monitors/MONITOR/desc** + +- Reading shows a description of the monitor *MONITOR* + +**monitors/MONITOR/enable** + +- Writing "0" disables the *MONITOR* +- Writing "1" enables the *MONITOR* +- Reading return the current status of the *MONITOR* + +**monitors/MONITOR/reactors** + +- List available reactors, with the select reaction for the given *MONITOR* + inside "[]". The default one is the nop (no operation) reactor. +- Writing the name of a reactor enables it to the given MONITOR. + +For example:: + + # cat monitors/wip/reactors + [nop] + panic + printk + # echo panic > monitors/wip/reactors + # cat monitors/wip/reactors + nop + [panic] + printk |