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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/i2c/gpio-fault-injection.rst
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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(). ...
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+=========================
+Linux I2C fault injection
+=========================
+
+The GPIO based I2C bus master driver can be configured to provide fault
+injection capabilities. It is then meant to be connected to another I2C bus
+which is driven by the I2C bus master driver under test. The GPIO fault
+injection driver can create special states on the bus which the other I2C bus
+master driver should handle gracefully.
+
+Once the Kconfig option I2C_GPIO_FAULT_INJECTOR is enabled, there will be an
+'i2c-fault-injector' subdirectory in the Kernel debugfs filesystem, usually
+mounted at /sys/kernel/debug. There will be a separate subdirectory per GPIO
+driven I2C bus. Each subdirectory will contain files to trigger the fault
+injection. They will be described now along with their intended use-cases.
+
+Wire states
+===========
+
+"scl"
+-----
+
+By reading this file, you get the current state of SCL. By writing, you can
+change its state to either force it low or to release it again. So, by using
+"echo 0 > scl" you force SCL low and thus, no communication will be possible
+because the bus master under test will not be able to clock. It should detect
+the condition of SCL being unresponsive and report an error to the upper
+layers.
+
+"sda"
+-----
+
+By reading this file, you get the current state of SDA. By writing, you can
+change its state to either force it low or to release it again. So, by using
+"echo 0 > sda" you force SDA low and thus, data cannot be transmitted. The bus
+master under test should detect this condition and trigger a bus recovery (see
+I2C specification version 4, section 3.1.16) using the helpers of the Linux I2C
+core (see 'struct bus_recovery_info'). However, the bus recovery will not
+succeed because SDA is still pinned low until you manually release it again
+with "echo 1 > sda". A test with an automatic release can be done with the
+"incomplete transfers" class of fault injectors.
+
+Incomplete transfers
+====================
+
+The following fault injectors create situations where SDA will be held low by a
+device. Bus recovery should be able to fix these situations. But please note:
+there are I2C client devices which detect a stuck SDA on their side and release
+it on their own after a few milliseconds. Also, there might be an external
+device deglitching and monitoring the I2C bus. It could also detect a stuck SDA
+and will init a bus recovery on its own. If you want to implement bus recovery
+in a bus master driver, make sure you checked your hardware setup for such
+devices before. And always verify with a scope or logic analyzer!
+
+"incomplete_address_phase"
+--------------------------
+
+This file is write only and you need to write the address of an existing I2C
+client device to it. Then, a read transfer to this device will be started, but
+it will stop at the ACK phase after the address of the client has been
+transmitted. Because the device will ACK its presence, this results in SDA
+being pulled low by the device while SCL is high. So, similar to the "sda" file
+above, the bus master under test should detect this condition and try a bus
+recovery. This time, however, it should succeed and the device should release
+SDA after toggling SCL.
+
+"incomplete_write_byte"
+-----------------------
+
+Similar to above, this file is write only and you need to write the address of
+an existing I2C client device to it.
+
+The injector will again stop at one ACK phase, so the device will keep SDA low
+because it acknowledges data. However, there are two differences compared to
+'incomplete_address_phase':
+
+a) the message sent out will be a write message
+b) after the address byte, a 0x00 byte will be transferred. Then, stop at ACK.
+
+This is a highly delicate state, the device is set up to write any data to
+register 0x00 (if it has registers) when further clock pulses happen on SCL.
+This is why bus recovery (up to 9 clock pulses) must either check SDA or send
+additional STOP conditions to ensure the bus has been released. Otherwise
+random data will be written to a device!
+
+Lost arbitration
+================
+
+Here, we want to simulate the condition where the master under test loses the
+bus arbitration against another master in a multi-master setup.
+
+"lose_arbitration"
+------------------
+
+This file is write only and you need to write the duration of the arbitration
+intereference (in µs, maximum is 100ms). The calling process will then sleep
+and wait for the next bus clock. The process is interruptible, though.
+
+Arbitration lost is achieved by waiting for SCL going down by the master under
+test and then pulling SDA low for some time. So, the I2C address sent out
+should be corrupted and that should be detected properly. That means that the
+address sent out should have a lot of '1' bits to be able to detect corruption.
+There doesn't need to be a device at this address because arbitration lost
+should be detected beforehand. Also note, that SCL going down is monitored
+using interrupts, so the interrupt latency might cause the first bits to be not
+corrupted. A good starting point for using this fault injector on an otherwise
+idle bus is::
+
+ # echo 200 > lose_arbitration &
+ # i2cget -y <bus_to_test> 0x3f
+
+Panic during transfer
+=====================
+
+This fault injector will create a Kernel panic once the master under test
+started a transfer. This usually means that the state machine of the bus master
+driver will be ungracefully interrupted and the bus may end up in an unusual
+state. Use this to check if your shutdown/reboot/boot code can handle this
+scenario.
+
+"inject_panic"
+--------------
+
+This file is write only and you need to write the delay between the detected
+start of a transmission and the induced Kernel panic (in µs, maximum is 100ms).
+The calling process will then sleep and wait for the next bus clock. The
+process is interruptible, though.
+
+Start of a transfer is detected by waiting for SCL going down by the master
+under test. A good starting point for using this fault injector is::
+
+ # echo 0 > inject_panic &
+ # i2cget -y <bus_to_test> <some_address>
+
+Note that there doesn't need to be a device listening to the address you are
+using. Results may vary depending on that, though.