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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/fprobe.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/fprobe.rst')
-rw-r--r-- | Documentation/trace/fprobe.rst | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/Documentation/trace/fprobe.rst b/Documentation/trace/fprobe.rst new file mode 100644 index 000000000..b64bec1ce --- /dev/null +++ b/Documentation/trace/fprobe.rst @@ -0,0 +1,174 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================== +Fprobe - Function entry/exit probe +================================== + +.. Author: Masami Hiramatsu <mhiramat@kernel.org> + +Introduction +============ + +Fprobe is a function entry/exit probe mechanism based on ftrace. +Instead of using ftrace full feature, if you only want to attach callbacks +on function entry and exit, similar to the kprobes and kretprobes, you can +use fprobe. Compared with kprobes and kretprobes, fprobe gives faster +instrumentation for multiple functions with single handler. This document +describes how to use fprobe. + +The usage of fprobe +=================== + +The fprobe is a wrapper of ftrace (+ kretprobe-like return callback) to +attach callbacks to multiple function entry and exit. User needs to set up +the `struct fprobe` and pass it to `register_fprobe()`. + +Typically, `fprobe` data structure is initialized with the `entry_handler` +and/or `exit_handler` as below. + +.. code-block:: c + + struct fprobe fp = { + .entry_handler = my_entry_callback, + .exit_handler = my_exit_callback, + }; + +To enable the fprobe, call one of register_fprobe(), register_fprobe_ips(), and +register_fprobe_syms(). These functions register the fprobe with different types +of parameters. + +The register_fprobe() enables a fprobe by function-name filters. +E.g. this enables @fp on "func*()" function except "func2()".:: + + register_fprobe(&fp, "func*", "func2"); + +The register_fprobe_ips() enables a fprobe by ftrace-location addresses. +E.g. + +.. code-block:: c + + unsigned long ips[] = { 0x.... }; + + register_fprobe_ips(&fp, ips, ARRAY_SIZE(ips)); + +And the register_fprobe_syms() enables a fprobe by symbol names. +E.g. + +.. code-block:: c + + char syms[] = {"func1", "func2", "func3"}; + + register_fprobe_syms(&fp, syms, ARRAY_SIZE(syms)); + +To disable (remove from functions) this fprobe, call:: + + unregister_fprobe(&fp); + +You can temporally (soft) disable the fprobe by:: + + disable_fprobe(&fp); + +and resume by:: + + enable_fprobe(&fp); + +The above is defined by including the header:: + + #include <linux/fprobe.h> + +Same as ftrace, the registered callbacks will start being called some time +after the register_fprobe() is called and before it returns. See +:file:`Documentation/trace/ftrace.rst`. + +Also, the unregister_fprobe() will guarantee that the both enter and exit +handlers are no longer being called by functions after unregister_fprobe() +returns as same as unregister_ftrace_function(). + +The fprobe entry/exit handler +============================= + +The prototype of the entry/exit callback function is as follows: + +.. code-block:: c + + void callback_func(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs); + +Note that both entry and exit callbacks have same ptototype. The @entry_ip is +saved at function entry and passed to exit handler. + +@fp + This is the address of `fprobe` data structure related to this handler. + You can embed the `fprobe` to your data structure and get it by + container_of() macro from @fp. The @fp must not be NULL. + +@entry_ip + This is the ftrace address of the traced function (both entry and exit). + Note that this may not be the actual entry address of the function but + the address where the ftrace is instrumented. + +@regs + This is the `pt_regs` data structure at the entry and exit. Note that + the instruction pointer of @regs may be different from the @entry_ip + in the entry_handler. If you need traced instruction pointer, you need + to use @entry_ip. On the other hand, in the exit_handler, the instruction + pointer of @regs is set to the currect return address. + +Share the callbacks with kprobes +================================ + +Since the recursion safeness of the fprobe (and ftrace) is a bit different +from the kprobes, this may cause an issue if user wants to run the same +code from the fprobe and the kprobes. + +Kprobes has per-cpu 'current_kprobe' variable which protects the kprobe +handler from recursion in all cases. On the other hand, fprobe uses +only ftrace_test_recursion_trylock(). This allows interrupt context to +call another (or same) fprobe while the fprobe user handler is running. + +This is not a matter if the common callback code has its own recursion +detection, or it can handle the recursion in the different contexts +(normal/interrupt/NMI.) +But if it relies on the 'current_kprobe' recursion lock, it has to check +kprobe_running() and use kprobe_busy_*() APIs. + +Fprobe has FPROBE_FL_KPROBE_SHARED flag to do this. If your common callback +code will be shared with kprobes, please set FPROBE_FL_KPROBE_SHARED +*before* registering the fprobe, like: + +.. code-block:: c + + fprobe.flags = FPROBE_FL_KPROBE_SHARED; + + register_fprobe(&fprobe, "func*", NULL); + +This will protect your common callback from the nested call. + +The missed counter +================== + +The `fprobe` data structure has `fprobe::nmissed` counter field as same as +kprobes. +This counter counts up when; + + - fprobe fails to take ftrace_recursion lock. This usually means that a function + which is traced by other ftrace users is called from the entry_handler. + + - fprobe fails to setup the function exit because of the shortage of rethook + (the shadow stack for hooking the function return.) + +The `fprobe::nmissed` field counts up in both cases. Therefore, the former +skips both of entry and exit callback and the latter skips the exit +callback, but in both case the counter will increase by 1. + +Note that if you set the FTRACE_OPS_FL_RECURSION and/or FTRACE_OPS_FL_RCU to +`fprobe::ops::flags` (ftrace_ops::flags) when registering the fprobe, this +counter may not work correctly, because ftrace skips the fprobe function which +increase the counter. + + +Functions and structures +======================== + +.. kernel-doc:: include/linux/fprobe.h +.. kernel-doc:: kernel/trace/fprobe.c + |