Currently, the BPF cgroup iterator supports walking descendants in
either pre-order (BPF_CGROUP_ITER_DESCENDANTS_PRE) or post-order
(BPF_CGROUP_ITER_DESCENDANTS_POST). These modes perform an exhaustive
depth-first search (DFS) of the hierarchy. In scenarios where a BPF
program may need to inspect only the direct children of a given parent
cgroup, a full DFS is unnecessarily expensive.
This patch introduces a new BPF cgroup iterator control option,
BPF_CGROUP_ITER_CHILDREN. This control option restricts the traversal
to the immediate children of a specified parent cgroup, allowing for
more targeted and efficient iteration, particularly when exhaustive
depth-first search (DFS) traversal is not required.
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Link: https://lore.kernel.org/r/20260127085112.3608687-1-mattbobrowski@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In a vain attempt to consolidate the email zoo switch everything to the
kernel.org account.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using libc types and headers from the UAPI headers is problematic as it
introduces a dependency on a full C toolchain.
Use the fixed-width integer types provided by the UAPI headers instead.
Fixes: 1602bad16d7d ("vfs: expose delegation support to userland")
Fixes: 4be9e04ebf75 ("vfs: add needed headers for new struct delegation definition")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20251203-uapi-fcntl-v1-1-490c67bf3425@linutronix.de
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add a new BPF command BPF_PROG_ASSOC_STRUCT_OPS to allow associating
a BPF program with a struct_ops map. This command takes a file
descriptor of a struct_ops map and a BPF program and set
prog->aux->st_ops_assoc to the kdata of the struct_ops map.
The command does not accept a struct_ops program nor a non-struct_ops
map. Programs of a struct_ops map is automatically associated with the
map during map update. If a program is shared between two struct_ops
maps, prog->aux->st_ops_assoc will be poisoned to indicate that the
associated struct_ops is ambiguous. The pointer, once poisoned, cannot
be reset since we have lost track of associated struct_ops. For other
program types, the associated struct_ops map, once set, cannot be
changed later. This restriction may be lifted in the future if there is
a use case.
A kernel helper bpf_prog_get_assoc_struct_ops() can be used to retrieve
the associated struct_ops pointer. The returned pointer, if not NULL, is
guaranteed to be valid and point to a fully updated struct_ops struct.
For struct_ops program reused in multiple struct_ops map, the return
will be NULL.
prog->aux->st_ops_assoc is protected by bumping the refcount for
non-struct_ops programs and RCU for struct_ops programs. Since it would
be inefficient to track programs associated with a struct_ops map, every
non-struct_ops program will bump the refcount of the map to make sure
st_ops_assoc stays valid. For a struct_ops program, it is protected by
RCU as map_free will wait for an RCU grace period before disassociating
the program with the map. The helper must be called in BPF program
context or RCU read-side critical section.
struct_ops implementers should note that the struct_ops returned may not
be initialized nor attached yet. The struct_ops implementer will be
responsible for tracking and checking the state of the associated
struct_ops map if the use case expects an initialized or attached
struct_ops.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/bpf/20251203233748.668365-3-ameryhung@gmail.com
Add a new state NAPI_STATE_THREADED_BUSY_POLL to the NAPI state enum to
enable and disable threaded busy polling.
When threaded busy polling is enabled for a NAPI, enable
NAPI_STATE_THREADED also.
When the threaded NAPI is scheduled, set NAPI_STATE_IN_BUSY_POLL to
signal napi_complete_done not to rearm interrupts.
Whenever NAPI_STATE_THREADED_BUSY_POLL is unset, the
NAPI_STATE_IN_BUSY_POLL will be unset, napi_complete_done unsets the
NAPI_STATE_SCHED_THREADED bit also, which in turn will make the kthread
go to sleep.
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Martin Karsten <mkarsten@uwaterloo.ca>
Tested-by: Martin Karsten <mkarsten@uwaterloo.ca>
Link: https://patch.msgid.link/20251028203007.575686-2-skhawaja@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If a socket has sk->sk_bypass_prot_mem flagged, the socket opts out
of the global protocol memory accounting.
This is easily controlled by net.core.bypass_prot_mem sysctl, but it
lacks flexibility.
Let's support flagging (and clearing) sk->sk_bypass_prot_mem via
bpf_setsockopt() at the BPF_CGROUP_INET_SOCK_CREATE hook.
int val = 1;
bpf_setsockopt(ctx, SOL_SOCKET, SK_BPF_BYPASS_PROT_MEM,
&val, sizeof(val));
As with net.core.bypass_prot_mem, this is inherited to child sockets,
and BPF always takes precedence over sysctl at socket(2) and accept(2).
SK_BPF_BYPASS_PROT_MEM is only supported at BPF_CGROUP_INET_SOCK_CREATE
and not supported on other hooks for some reasons:
1. UDP charges memory under sk->sk_receive_queue.lock instead
of lock_sock()
2. Modifying the flag after skb is charged to sk requires such
adjustment during bpf_setsockopt() and complicates the logic
unnecessarily
We can support other hooks later if a real use case justifies that.
Most changes are inline and hard to trace, but a microbenchmark on
__sk_mem_raise_allocated() during neper/tcp_stream showed that more
samples completed faster with sk->sk_bypass_prot_mem == 1. This will
be more visible under tcp_mem pressure (but it's not a fair comparison).
# bpftrace -e 'kprobe:__sk_mem_raise_allocated { @start[tid] = nsecs; }
kretprobe:__sk_mem_raise_allocated /@start[tid]/
{ @end[tid] = nsecs - @start[tid]; @times = hist(@end[tid]); delete(@start[tid]); }'
# tcp_stream -6 -F 1000 -N -T 256
Without bpf prog:
[128, 256) 3846 | |
[256, 512) 1505326 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[512, 1K) 1371006 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ |
[1K, 2K) 198207 |@@@@@@ |
[2K, 4K) 31199 |@ |
With bpf prog in the next patch:
(must be attached before tcp_stream)
# bpftool prog load sk_bypass_prot_mem.bpf.o /sys/fs/bpf/test type cgroup/sock_create
# bpftool cgroup attach /sys/fs/cgroup/test cgroup_inet_sock_create pinned /sys/fs/bpf/test
[128, 256) 6413 | |
[256, 512) 1868425 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[512, 1K) 1101697 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ |
[1K, 2K) 117031 |@@@@ |
[2K, 4K) 11773 | |
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Link: https://patch.msgid.link/20251014235604.3057003-6-kuniyu@google.com
Arm FEAT_SPE_FDS adds the ability to filter on the data source of a
packet using another 64-bits of event filtering control. As the existing
perf_event_attr::configN fields are all used up for SPE PMU, an
additional field is needed. Add a new 'config4' field.
Reviewed-by: Leo Yan <leo.yan@arm.com>
Tested-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>
Add support for deferred userspace unwind to perf.
Where perf currently relies on in-place stack unwinding; from NMI
context and all that. This moves the userspace part of the unwind to
right before the return-to-userspace.
This has two distinct benefits, the biggest is that it moves the
unwind to a faultable context. It becomes possible to fault in debug
info (.eh_frame, SFrame etc.) that might not otherwise be readily
available. And secondly, it de-duplicates the user callchain where
multiple samples happen during the same kernel entry.
To facilitate this the perf interface is extended with a new record
type:
PERF_RECORD_CALLCHAIN_DEFERRED
and two new attribute flags:
perf_event_attr::defer_callchain - to request the user unwind be deferred
perf_event_attr::defer_output - to request PERF_RECORD_CALLCHAIN_DEFERRED records
The existing PERF_RECORD_SAMPLE callchain section gets a new
context type:
PERF_CONTEXT_USER_DEFERRED
After which will come a single entry, denoting the 'cookie' of the
deferred callchain that should be attached here, matching the 'cookie'
field of the above mentioned PERF_RECORD_CALLCHAIN_DEFERRED.
The 'defer_callchain' flag is expected on all events with
PERF_SAMPLE_CALLCHAIN. The 'defer_output' flag is expect on the event
responsible for collecting side-band events (like mmap, comm etc.).
Setting 'defer_output' on multiple events will get you duplicated
PERF_RECORD_CALLCHAIN_DEFERRED records.
Based on earlier patches by Josh and Steven.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251023150002.GR4067720@noisy.programming.kicks-ass.net
The definition of struct delegation uses stdint.h integer types. Add the
necessary headers to ensure that always works.
Fixes: 1602bad16d7d ("vfs: expose delegation support to userland")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Now that support for recallable directory delegations is available,
expose this functionality to userland with new F_SETDELEG and F_GETDELEG
commands for fcntl().
Note that this also allows userland to request a FL_DELEG type lease on
files too. Userland applications that do will get signalled when there
are metadata changes in addition to just data changes (which is a
limitation of FL_LEASE leases).
These commands accept a new "struct delegation" argument that contains a
flags field for future expansion.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-17-52f3feebb2f2@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
On bpf(BPF_PROG_LOAD) syscall user-supplied BPF programs are
translated by the verifier into "xlated" BPF programs. During this
process the original instructions offsets might be adjusted and/or
individual instructions might be replaced by new sets of instructions,
or deleted.
Add a new BPF map type which is aimed to keep track of how, for a
given program, the original instructions were relocated during the
verification. Also, besides keeping track of the original -> xlated
mapping, make x86 JIT to build the xlated -> jitted mapping for every
instruction listed in an instruction array. This is required for every
future application of instruction arrays: static keys, indirect jumps
and indirect calls.
A map of the BPF_MAP_TYPE_INSN_ARRAY type must be created with a u32
keys and value of size 8. The values have different semantics for
userspace and for BPF space. For userspace a value consists of two
u32 values – xlated and jitted offsets. For BPF side the value is
a real pointer to a jitted instruction.
On map creation/initialization, before loading the program, each
element of the map should be initialized to point to an instruction
offset within the program. Before the program load such maps should
be made frozen. After the program verification xlated and jitted
offsets can be read via the bpf(2) syscall.
If a tracked instruction is removed by the verifier, then the xlated
offset is set to (u32)-1 which is considered to be too big for a valid
BPF program offset.
One such a map can, obviously, be used to track one and only one BPF
program. If the verification process was unsuccessful, then the same
map can be re-used to verify the program with a different log level.
However, if the program was loaded fine, then such a map, being
frozen in any case, can't be reused by other programs even after the
program release.
Example. Consider the following original and xlated programs:
Original prog: Xlated prog:
0: r1 = 0x0 0: r1 = 0
1: *(u32 *)(r10 - 0x4) = r1 1: *(u32 *)(r10 -4) = r1
2: r2 = r10 2: r2 = r10
3: r2 += -0x4 3: r2 += -4
4: r1 = 0x0 ll 4: r1 = map[id:88]
6: call 0x1 6: r1 += 272
7: r0 = *(u32 *)(r2 +0)
8: if r0 >= 0x1 goto pc+3
9: r0 <<= 3
10: r0 += r1
11: goto pc+1
12: r0 = 0
7: r6 = r0 13: r6 = r0
8: if r6 == 0x0 goto +0x2 14: if r6 == 0x0 goto pc+4
9: call 0x76 15: r0 = 0xffffffff8d2079c0
17: r0 = *(u64 *)(r0 +0)
10: *(u64 *)(r6 + 0x0) = r0 18: *(u64 *)(r6 +0) = r0
11: r0 = 0x0 19: r0 = 0x0
12: exit 20: exit
An instruction array map, containing, e.g., instructions [0,4,7,12]
will be translated by the verifier to [0,4,13,20]. A map with
index 5 (the middle of 16-byte instruction) or indexes greater than 12
(outside the program boundaries) would be rejected.
The functionality provided by this patch will be extended in consequent
patches to implement BPF Static Keys, indirect jumps, and indirect calls.
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251105090410.1250500-2-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Dynptr currently caps size and offset at 24 bits, which isn’t sufficient
for file-backed use cases; even 32 bits can be limiting. Refactor dynptr
helpers/kfuncs to use 64-bit size and offset, ensuring consistency
across the APIs.
This change does not affect internals of xdp, skb or other dynptrs,
which continue to behave as before. Also it does not break binary
compatibility.
The widening enables large-file access support via dynptr, implemented
in the next patches.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251026203853.135105-3-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
On Android/Termux, linux/types.h is included (indirectly) by sys/epoll.h which
depends on this definition to be present.
Signed-off-by: Alain Knaff <github@misc.lka.org.lu>
The commit 1b8abbb12128 ("bpf...d_path(): constify path argument")
constified the first parameter of the bpf_d_path(), but failed to
update it in all places. Finish constification.
Otherwise the selftest fail to build:
.../selftests/bpf/bpf_experimental.h:222:12: error: conflicting types for 'bpf_path_d_path'
222 | extern int bpf_path_d_path(const struct path *path, char *buf, size_t buf__sz) __ksym;
| ^
.../selftests/bpf/tools/include/vmlinux.h:153922:12: note: previous declaration is here
153922 | extern int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz) __weak __ksym;
Fixes: 1b8abbb12128 ("bpf...d_path(): constify path argument")
Signed-off-by: Rong Tao <rongtao@cestc.cn>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Various network interface types make use of needed_{head,tail}room values
to efficiently reserve buffer space for additional encapsulation headers,
such as VXLAN, Geneve, IPSec, etc. However, it is not currently possible
to query these values in a generic way.
Introduce ability to query the needed_{head,tail}room values of a network
device via rtnetlink, such that applications that may wish to use these
values can do so.
For example, Cilium agent iterates over present devices based on user config
(direct routing, vxlan, geneve, wireguard etc.) and in future will configure
netkit in order to expose the needed_{head,tail}room into K8s pods. See
b9ed315d3c4c ("netkit: Allow for configuring needed_{head,tail}room").
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alasdair McWilliam <alasdair@mcwilliam.dev>
Reviewed-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://patch.msgid.link/20250917095543.14039-1-alasdair@mcwilliam.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Introduce a new netlink attribute 'actor_port_prio' to allow setting
the LACP actor port priority on a per-slave basis. This extends the
existing bonding infrastructure to support more granular control over
LACP negotiations.
The priority value is embedded in LACPDU packets and will be used by
subsequent patches to influence aggregator selection policies.
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://patch.msgid.link/20250902064501.360822-2-liuhangbin@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The uAPI stddef header includes compiler_types.h, a kernel-only
header, to make sure that kernel definitions of annotations
like __counted_by() take precedence.
There is a hack in scripts/headers_install.sh which strips includes
of compiler.h and compiler_types.h when installing uAPI headers.
While explicit handling makes sense for compiler.h, which is included
all over the uAPI, compiler_types.h is only included by stddef.h
(within the uAPI, obviously it's included in kernel code a lot).
Remove the stripping from scripts/headers_install.sh and wrap
the include of compiler_types.h in #ifdef __KERNEL__ instead.
This should be equivalent functionally, but is easier to understand
to a casual reader of the code. It also makes it easier to work
with kernel headers directly from under tools/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250825201828.2370083-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This patch adds necessary plumbing in verifier, syscall and maps to
support handling new kfunc bpf_task_work_schedule and kernel structure
bpf_task_work. The idea is similar to how we already handle bpf_wq and
bpf_timer.
verifier changes validate calls to bpf_task_work_schedule to make sure
it is safe and expected invariants hold.
btf part is required to detect bpf_task_work structure inside map value
and store its offset, which will be used in the next patch to calculate
key and value addresses.
arraymap and hashtab changes are needed to handle freeing of the
bpf_task_work: run code needed to deinitialize it, for example cancel
task_work callback if possible.
The use of bpf_task_work and proper implementation for kfuncs are
introduced in the next patch.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250923112404.668720-6-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch extends the BPF_PROG_LOAD command by adding three new fields
to `union bpf_attr` in the user-space API:
- signature: A pointer to the signature blob.
- signature_size: The size of the signature blob.
- keyring_id: The serial number of a loaded kernel keyring (e.g.,
the user or session keyring) containing the trusted public keys.
When a BPF program is loaded with a signature, the kernel:
1. Retrieves the trusted keyring using the provided `keyring_id`.
2. Verifies the supplied signature against the BPF program's
instruction buffer.
3. If the signature is valid and was generated by a key in the trusted
keyring, the program load proceeds.
4. If no signature is provided, the load proceeds as before, allowing
for backward compatibility. LSMs can chose to restrict unsigned
programs and implement a security policy.
5. If signature verification fails for any reason,
the program is not loaded.
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250921160120.9711-2-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently only array maps are supported, but the implementation can be
extended for other maps and objects. The hash is memoized only for
exclusive and frozen maps as their content is stable until the exclusive
program modifies the map.
This is required for BPF signing, enabling a trusted loader program to
verify a map's integrity. The loader retrieves
the map's runtime hash from the kernel and compares it against an
expected hash computed at build time.
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-7-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Exclusive maps allow maps to only be accessed by program with a
program with a matching hash which is specified in the excl_prog_hash
attr.
For the signing use-case, this allows the trusted loader program
to load the map and verify the integrity
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-3-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pidfd file handles are exhaustive meaning they don't require a handle on
another pidfd to pass to open_by_handle_at() so it can derive the
filesystem to decode in. Instead it can be derived from the file
handle itself. The same is possible for namespace file handles.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
libbpf is now using above macros for libbpf_sha256() implementation,
make them available in Github repo.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Some of them were outdated, again due to originally using UAPI headers
from tools/ subdirectory in Linux repo.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
They were removed during one of the syncs because Linux repo's tools/
versions of UAPI headers were removed (as they were not needed for perf
anymore). This is no right for libbpf, so add them back. And moving
forward, we'll sync them from Linux repo original UAPIs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Instead of using '0' and '1' for napi threaded state use an enum with
'disabled' and 'enabled' states.
Tested:
./tools/testing/selftests/net/nl_netdev.py
TAP version 13
1..7
ok 1 nl_netdev.empty_check
ok 2 nl_netdev.lo_check
ok 3 nl_netdev.page_pool_check
ok 4 nl_netdev.napi_list_check
ok 5 nl_netdev.dev_set_threaded
ok 6 nl_netdev.napi_set_threaded
ok 7 nl_netdev.nsim_rxq_reset_down
# Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
Link: https://patch.msgid.link/20250723013031.2911384-4-skhawaja@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
A net device has a threaded sysctl that can be used to enable threaded
NAPI polling on all of the NAPI contexts under that device. Allow
enabling threaded NAPI polling at individual NAPI level using netlink.
Extend the netlink operation `napi-set` and allow setting the threaded
attribute of a NAPI. This will enable the threaded polling on a NAPI
context.
Add a test in `nl_netdev.py` that verifies various cases of threaded
NAPI being set at NAPI and at device level.
Tested
./tools/testing/selftests/net/nl_netdev.py
TAP version 13
1..7
ok 1 nl_netdev.empty_check
ok 2 nl_netdev.lo_check
ok 3 nl_netdev.page_pool_check
ok 4 nl_netdev.napi_list_check
ok 5 nl_netdev.dev_set_threaded
ok 6 nl_netdev.napi_set_threaded
ok 7 nl_netdev.nsim_rxq_reset_down
# Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0
Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250710211203.3979655-1-skhawaja@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This patch provides a setsockopt method to let applications leverage to
adjust how many descs to be handled at most in one send syscall. It
mitigates the situation where the default value (32) that is too small
leads to higher frequency of triggering send syscall.
Considering the prosperity/complexity the applications have, there is no
absolutely ideal suggestion fitting all cases. So keep 32 as its default
value like before.
The patch does the following things:
- Add XDP_MAX_TX_SKB_BUDGET socket option.
- Set max_tx_budget to 32 by default in the initialization phase as a
per-socket granular control.
- Set the range of max_tx_budget as [32, xs->tx->nentries].
The idea behind this comes out of real workloads in production. We use a
user-level stack with xsk support to accelerate sending packets and
minimize triggering syscalls. When the packets are aggregated, it's not
hard to hit the upper bound (namely, 32). The moment user-space stack
fetches the -EAGAIN error number passed from sendto(), it will loop to try
again until all the expected descs from tx ring are sent out to the driver.
Enlarging the XDP_MAX_TX_SKB_BUDGET value contributes to less frequency of
sendto() and higher throughput/PPS.
Here is what I did in production, along with some numbers as follows:
For one application I saw lately, I suggested using 128 as max_tx_budget
because I saw two limitations without changing any default configuration:
1) XDP_MAX_TX_SKB_BUDGET, 2) socket sndbuf which is 212992 decided by
net.core.wmem_default. As to XDP_MAX_TX_SKB_BUDGET, the scenario behind
this was I counted how many descs are transmitted to the driver at one
time of sendto() based on [1] patch and then I calculated the
possibility of hitting the upper bound. Finally I chose 128 as a
suitable value because 1) it covers most of the cases, 2) a higher
number would not bring evident results. After twisting the parameters,
a stable improvement of around 4% for both PPS and throughput and less
resources consumption were found to be observed by strace -c -p xxx:
1) %time was decreased by 7.8%
2) error counter was decreased from 18367 to 572
[1]: https://lore.kernel.org/all/20250619093641.70700-1-kerneljasonxing@gmail.com/
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://patch.msgid.link/20250704160138.48677-1-kerneljasonxing@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The 'commit 35f96de04127 ("bpf: Introduce BPF token object")' added
BPF token as a new kind of BPF kernel object. And BPF_OBJ_GET_INFO_BY_FD
already used to get BPF object info, so we can also get token info with
this cmd.
One usage scenario, when program runs failed with token, because of
the permission failure, we can report what BPF token is allowing with
this API for debugging.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Link: https://lore.kernel.org/r/20250716134654.1162635-1-chen.dylane@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support for a stream API to the kernel and expose related kfuncs to
BPF programs. Two streams are exposed, BPF_STDOUT and BPF_STDERR. These
can be used for printing messages that can be consumed from user space,
thus it's similar in spirit to existing trace_pipe interface.
The kernel will use the BPF_STDERR stream to notify the program of any
errors encountered at runtime. BPF programs themselves may use both
streams for writing debug messages. BPF library-like code may use
BPF_STDERR to print warnings or errors on misuse at runtime.
The implementation of a stream is as follows. Everytime a message is
emitted from the kernel (directly, or through a BPF program), a record
is allocated by bump allocating from per-cpu region backed by a page
obtained using alloc_pages_nolock(). This ensures that we can allocate
memory from any context. The eventual plan is to discard this scheme in
favor of Alexei's kmalloc_nolock() [0].
This record is then locklessly inserted into a list (llist_add()) so
that the printing side doesn't require holding any locks, and works in
any context. Each stream has a maximum capacity of 4MB of text, and each
printed message is accounted against this limit.
Messages from a program are emitted using the bpf_stream_vprintk kfunc,
which takes a stream_id argument in addition to working otherwise
similar to bpf_trace_vprintk.
The bprintf buffer helpers are extracted out to be reused for printing
the string into them before copying it into the stream, so that we can
(with the defined max limit) format a string and know its true length
before performing allocations of the stream element.
For consuming elements from a stream, we expose a bpf(2) syscall command
named BPF_PROG_STREAM_READ_BY_FD, which allows reading data from the
stream of a given prog_fd into a user space buffer. The main logic is
implemented in bpf_stream_read(). The log messages are queued in
bpf_stream::log by the bpf_stream_vprintk kfunc, and then pulled and
ordered correctly in the stream backlog.
For this purpose, we hold a lock around bpf_stream_backlog_peek(), as
llist_del_first() (if we maintained a second lockless list for the
backlog) wouldn't be safe from multiple threads anyway. Then, if we
fail to find something in the backlog log, we splice out everything from
the lockless log, and place it in the backlog log, and then return the
head of the backlog. Once the full length of the element is consumed, we
will pop it and free it.
The lockless list bpf_stream::log is a LIFO stack. Elements obtained
using a llist_del_all() operation are in LIFO order, thus would break
the chronological ordering if printed directly. Hence, this batch of
messages is first reversed. Then, it is stashed into a separate list in
the stream, i.e. the backlog_log. The head of this list is the actual
message that should always be returned to the caller. All of this is
done in bpf_stream_backlog_fill().
From the kernel side, the writing into the stream will be a bit more
involved than the typical printk. First, the kernel typically may print
a collection of messages into the stream, and parallel writers into the
stream may suffer from interleaving of messages. To ensure each group of
messages is visible atomically, we can lift the advantage of using a
lockless list for pushing in messages.
To enable this, we add a bpf_stream_stage() macro, and require kernel
users to use bpf_stream_printk statements for the passed expression to
write into the stream. Underneath the macro, we have a message staging
API, where a bpf_stream_stage object on the stack accumulates the
messages being printed into a local llist_head, and then a commit
operation splices the whole batch into the stream's lockless log list.
This is especially pertinent for rqspinlock deadlock messages printed to
program streams. After this change, we see each deadlock invocation as a
non-interleaving contiguous message without any confusion on the
reader's part, improving their user experience in debugging the fault.
While programs cannot benefit from this staged stream writing API, they
could just as well hold an rqspinlock around their print statements to
serialize messages, hence this is kept kernel-internal for now.
Overall, this infrastructure provides NMI-safe any context printing of
messages to two dedicated streams.
Later patches will add support for printing splats in case of BPF arena
page faults, rqspinlock deadlocks, and cond_break timeouts, and
integration of this facility into bpftool for dumping messages to user
space.
[0]: https://lore.kernel.org/bpf/20250501032718.65476-1-alexei.starovoitov@gmail.com
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In Cilium, we use bpf_csum_diff + bpf_l4_csum_replace to, among other
things, update the L4 checksum after reverse SNATing IPv6 packets. That
use case is however not currently supported and leads to invalid
skb->csum values in some cases. This patch adds support for IPv6 address
changes in bpf_l4_csum_update via a new flag.
When calling bpf_l4_csum_replace in Cilium, it ends up calling
inet_proto_csum_replace_by_diff:
1: void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
2: __wsum diff, bool pseudohdr)
3: {
4: if (skb->ip_summed != CHECKSUM_PARTIAL) {
5: csum_replace_by_diff(sum, diff);
6: if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
7: skb->csum = ~csum_sub(diff, skb->csum);
8: } else if (pseudohdr) {
9: *sum = ~csum_fold(csum_add(diff, csum_unfold(*sum)));
10: }
11: }
The bug happens when we're in the CHECKSUM_COMPLETE state. We've just
updated one of the IPv6 addresses. The helper now updates the L4 header
checksum on line 5. Next, it updates skb->csum on line 7. It shouldn't.
For an IPv6 packet, the updates of the IPv6 address and of the L4
checksum will cancel each other. The checksums are set such that
computing a checksum over the packet including its checksum will result
in a sum of 0. So the same is true here when we update the L4 checksum
on line 5. We'll update it as to cancel the previous IPv6 address
update. Hence skb->csum should remain untouched in this case.
The same bug doesn't affect IPv4 packets because, in that case, three
fields are updated: the IPv4 address, the IP checksum, and the L4
checksum. The change to the IPv4 address and one of the checksums still
cancel each other in skb->csum, but we're left with one checksum update
and should therefore update skb->csum accordingly. That's exactly what
inet_proto_csum_replace_by_diff does.
This special case for IPv6 L4 checksums is also described atop
inet_proto_csum_replace16, the function we should be using in this case.
This patch introduces a new bpf_l4_csum_replace flag, BPF_F_IPV6,
to indicate that we're updating the L4 checksum of an IPv6 packet. When
the flag is set, inet_proto_csum_replace_by_diff will skip the
skb->csum update.
Fixes: 7d672345ed295 ("bpf: add generic bpf_csum_diff helper")
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://patch.msgid.link/96a6bc3a443e6f0b21ff7b7834000e17fb549e05.1748509484.git.paul.chaignon@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The sample file was renamed from trace_output_kern.c to
trace_output.bpf.c in commit d4fffba4d04b ("samples/bpf: Change _kern
suffix to .bpf with syscall tracing program"). Adjust the path in the
documentation comment for bpf_perf_event_output.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Link: https://lore.kernel.org/r/20250610140756.16332-1-tklauser@distanz.ch
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Current cgroup prog ordering is appending at attachment time. This is not
ideal. In some cases, users want specific ordering at a particular cgroup
level. To address this, the existing mprog API seems an ideal solution with
supporting BPF_F_BEFORE and BPF_F_AFTER flags.
But there are a few obstacles to directly use kernel mprog interface.
Currently cgroup bpf progs already support prog attach/detach/replace
and link-based attach/detach/replace. For example, in struct
bpf_prog_array_item, the cgroup_storage field needs to be together
with bpf prog. But the mprog API struct bpf_mprog_fp only has bpf_prog
as the member, which makes it difficult to use kernel mprog interface.
In another case, the current cgroup prog detach tries to use the
same flag as in attach. This is different from mprog kernel interface
which uses flags passed from user space.
So to avoid modifying existing behavior, I made the following changes to
support mprog API for cgroup progs:
- The support is for prog list at cgroup level. Cross-level prog list
(a.k.a. effective prog list) is not supported.
- Previously, BPF_F_PREORDER is supported only for prog attach, now
BPF_F_PREORDER is also supported by link-based attach.
- For attach, BPF_F_BEFORE/BPF_F_AFTER/BPF_F_ID/BPF_F_LINK is supported
similar to kernel mprog but with different implementation.
- For detach and replace, use the existing implementation.
- For attach, detach and replace, the revision for a particular prog
list, associated with a particular attach type, will be updated
by increasing count by 1.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250606163141.2428937-1-yonghong.song@linux.dev
When applying a recent commit to the <uapi/linux/perf_event.h>
header I noticed that we have accumulated quite a bit of
historic noise in this header, so do a bit of spring cleaning:
- Define bitfields in a vertically aligned fashion, like
perf_event_mmap_page::capabilities already does. This
makes it easier to see the distribution and sizing of
bits within a word, at a glance. The following is much
more readable:
__u64 cap_bit0 : 1,
cap_bit0_is_deprecated : 1,
cap_user_rdpmc : 1,
cap_user_time : 1,
cap_user_time_zero : 1,
cap_user_time_short : 1,
cap_____res : 58;
Than:
__u64 cap_bit0:1,
cap_bit0_is_deprecated:1,
cap_user_rdpmc:1,
cap_user_time:1,
cap_user_time_zero:1,
cap_user_time_short:1,
cap_____res:58;
So convert all bitfield definitions from the latter style to the
former style.
- Fix typos and grammar
- Fix capitalization
- Remove whitespace noise
- Harmonize the definitions of various generations and groups of
PERF_MEM_ ABI values.
- Vertically align all definitions and assignments to the same
column (48), as the first definition (enum perf_type_id),
throughout the entire header.
- And in general make the code and comments to be more in sync
with each other and to be more readable overall.
No change in functionality.
Copy the changes over to tools/include/uapi/linux/perf_event.h.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250521221529.2547099-1-irogers@google.com
Normalize already synced UAPI headers. For all subsequent syncs this
will be done automatically by the sync script.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
