kernel/linux.git/Documentation/bpf, branch v7.0-rc7

Merge tag 'bpf-next-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2026-02-10T19:26:21+00:00

Pull bpf updates from Alexei Starovoitov: - Support associating BPF program with struct_ops (Amery Hung) - Switch BPF local storage to rqspinlock and remove recursion detection counters which were causing false positives (Amery Hung) - Fix live registers marking for indirect jumps (Anton Protopopov) - Introduce execution context detection BPF helpers (Changwoo Min) - Improve verifier precision for 32bit sign extension pattern (Cupertino Miranda) - Optimize BTF type lookup by sorting vmlinux BTF and doing binary search (Donglin Peng) - Allow states pruning for misc/invalid slots in iterator loops (Eduard Zingerman) - In preparation for ASAN support in BPF arenas teach libbpf to move global BPF variables to the end of the region and enable arena kfuncs while holding locks (Emil Tsalapatis) - Introduce support for implicit arguments in kfuncs and migrate a number of them to new API. This is a prerequisite for cgroup sub-schedulers in sched-ext (Ihor Solodrai) - Fix incorrect copied_seq calculation in sockmap (Jiayuan Chen) - Fix ORC stack unwind from kprobe_multi (Jiri Olsa) - Speed up fentry attach by using single ftrace direct ops in BPF trampolines (Jiri Olsa) - Require frozen map for calculating map hash (KP Singh) - Fix lock entry creation in TAS fallback in rqspinlock (Kumar Kartikeya Dwivedi) - Allow user space to select cpu in lookup/update operations on per-cpu array and hash maps (Leon Hwang) - Make kfuncs return trusted pointers by default (Matt Bobrowski) - Introduce "fsession" support where single BPF program is executed upon entry and exit from traced kernel function (Menglong Dong) - Allow bpf_timer and bpf_wq use in all programs types (Mykyta Yatsenko, Andrii Nakryiko, Kumar Kartikeya Dwivedi, Alexei Starovoitov) - Make KF_TRUSTED_ARGS the default for all kfuncs and clean up their definition across the tree (Puranjay Mohan) - Allow BPF arena calls from non-sleepable context (Puranjay Mohan) - Improve register id comparison logic in the verifier and extend linked registers with negative offsets (Puranjay Mohan) - In preparation for BPF-OOM introduce kfuncs to access memcg events (Roman Gushchin) - Use CFI compatible destructor kfunc type (Sami Tolvanen) - Add bitwise tracking for BPF_END in the verifier (Tianci Cao) - Add range tracking for BPF_DIV and BPF_MOD in the verifier (Yazhou Tang) - Make BPF selftests work with 64k page size (Yonghong Song) * tag 'bpf-next-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (268 commits) selftests/bpf: Fix outdated test on storage->smap selftests/bpf: Choose another percpu variable in bpf for btf_dump test selftests/bpf: Remove test_task_storage_map_stress_lookup selftests/bpf: Update task_local_storage/task_storage_nodeadlock test selftests/bpf: Update task_local_storage/recursion test selftests/bpf: Update sk_storage_omem_uncharge test bpf: Switch to bpf_selem_unlink_nofail in bpf_local_storage_{map_free, destroy} bpf: Support lockless unlink when freeing map or local storage bpf: Prepare for bpf_selem_unlink_nofail() bpf: Remove unused percpu counter from bpf_local_storage_map_free bpf: Remove cgroup local storage percpu counter bpf: Remove task local storage percpu counter bpf: Change local_storage->lock and b->lock to rqspinlock bpf: Convert bpf_selem_unlink to failable bpf: Convert bpf_selem_link_map to failable bpf: Convert bpf_selem_unlink_map to failable bpf: Select bpf_local_storage_map_bucket based on bpf_local_storage selftests/xsk: fix number of Tx frags in invalid packet selftests/xsk: properly handle batch ending in the middle of a packet bpf: Prevent reentrance into call_rcu_tasks_trace() ...

Documentation: use a source-read extension for the index link boilerplate

2026-01-23T18:59:34+00:00

The root document usually has a special :ref:`genindex` link to the generated index. This is also the case for Documentation/index.rst. The other index.rst files deeper in the directory hierarchy usually don't. For SPHINXDIRS builds, the root document isn't Documentation/index.rst, but some other index.rst in the hierarchy. Currently they have a ".. only::" block to add the index link when doing SPHINXDIRS html builds. This is obviously very tedious and repetitive. The link is also added to all index.rst files in the hierarchy for SPHINXDIRS builds, not just the root document. Put the boilerplate in a sphinx-includes/subproject-index.rst file, and include it at the end of the root document for subproject builds in an ad-hoc source-read extension defined in conf.py. For now, keep having the boilerplate in translations, because this approach currently doesn't cover translated index link headers. Cc: Jonathan Corbet Cc: Mauro Carvalho Chehab Cc: Randy Dunlap Signed-off-by: Jani Nikula Tested-by: Mauro Carvalho Chehab Reviewed-by: Mauro Carvalho Chehab [jc: did s/doctree/kern_doc_dir/ ] Signed-off-by: Jonathan Corbet Message-ID: <20260123143149.2024303-1-jani.nikula@intel.com>

bpf,docs: Document KF_IMPLICIT_ARGS flag

2026-01-21T00:22:38+00:00

Add a section explaining KF_IMPLICIT_ARGS kfunc flag. Remove __prog arg annotation, as it is no longer supported. Signed-off-by: Ihor Solodrai Link: https://lore.kernel.org/r/20260120223027.3981805-1-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov

bpf: Replace opt annotation with nullable for kfuncs

2026-01-02T23:51:34+00:00

The __opt annotation was originally introduced specifically for buffer/size argument pairs in bpf_dynptr_slice() and bpf_dynptr_slice_rdwr(), allowing the buffer pointer to be NULL while still validating the size as a constant. The __nullable annotation serves the same purpose but is more general and is already used throughout the BPF subsystem for raw tracepoints, struct_ops, and other kfuncs. This patch unifies the two annotations by replacing __opt with __nullable. The key change is in the verifier's get_kfunc_ptr_arg_type() function, where mem/size pair detection is now performed before the nullable check. This ensures that buffer/size pairs are correctly classified as KF_ARG_PTR_TO_MEM_SIZE even when the buffer is nullable, while adding an !arg_mem_size condition to the nullable check prevents interference with mem/size pair handling. When processing KF_ARG_PTR_TO_MEM_SIZE arguments, the verifier now uses is_kfunc_arg_nullable() instead of the removed is_kfunc_arg_optional() to determine whether to skip size validation for NULL buffers. This is the first documentation added for the __nullable annotation, which has been in use since it was introduced but was previously undocumented. No functional changes to verifier behavior - nullable buffer/size pairs continue to work exactly as before. Acked-by: Eduard Zingerman Signed-off-by: Puranjay Mohan Link: https://lore.kernel.org/r/20260102221513.1961781-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov

bpf: Make KF_TRUSTED_ARGS the default for all kfuncs

2026-01-02T20:04:28+00:00

Change the verifier to make trusted args the default requirement for all kfuncs by removing is_kfunc_trusted_args() assuming it be to always return true. This works because: 1. Context pointers (xdp_md, __sk_buff, etc.) are handled through their own KF_ARG_PTR_TO_CTX case label and bypass the trusted check 2. Struct_ops callback arguments are already marked as PTR_TRUSTED during initialization and pass is_trusted_reg() 3. KF_RCU kfuncs are handled separately via is_kfunc_rcu() checks at call sites (always checked with || alongside is_kfunc_trusted_args) This simple change makes all kfuncs require trusted args by default while maintaining correct behavior for all existing special cases. Note: This change means kfuncs that previously accepted NULL pointers without KF_TRUSTED_ARGS will now reject NULL at verification time. Several netfilter kfuncs are affected: bpf_xdp_ct_lookup(), bpf_skb_ct_lookup(), bpf_xdp_ct_alloc(), and bpf_skb_ct_alloc() all accept NULL for their bpf_tuple and opts parameters internally (checked in __bpf_nf_ct_lookup), but after this change the verifier rejects NULL before the kfunc is even called. This is acceptable because these kfuncs don't work with NULL parameters in their proper usage. Now they will be rejected rather than returning an error, which shouldn't make a difference to BPF programs that were using these kfuncs properly. Acked-by: Eduard Zingerman Reviewed-by: Emil Tsalapatis Signed-off-by: Puranjay Mohan Link: https://lore.kernel.org/r/20260102180038.2708325-2-puranjay@kernel.org Signed-off-by: Alexei Starovoitov

bpf: Update BPF_PROG_RUN documentation

2025-12-31T21:45:26+00:00

LWT_SEG6LOCAL no longer supports test_run starting from v6.11 so remove it from the list of program types supported by BPF_PROG_RUN. Add TRACING and NETFILTER program types to reflect the current set of types that implement test_run. Signed-off-by: SungRock Jung Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20251221070041.26592-1-tjdfkr2421@gmail.com Signed-off-by: Alexei Starovoitov

docs: bpf: map_array: Specify BPF_MAP_TYPE_PERCPU_ARRAY value size limit

2025-11-25T22:32:00+00:00

Specify value size limit for BPF_MAP_TYPE_PERCPU_ARRAY which is PCPU_MIN_UNIT_SIZE (32 kb). In percpu allocator (mm: percpu), any request with a size greater than PCPU_MIN_UNIT_SIZE is rejected. Signed-off-by: Alex Tran Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251115063531.2302903-1-alex.t.tran@gmail.com

docs/bpf: Add missing BPF k/uprobe program types to docs

2025-11-04T18:24:43+00:00

Update the table of program types in the libbpf docs with the missing k/uprobe multi and session program types. Signed-off-by: Donald Hunter Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251029180932.98038-1-donald.hunter@gmail.com

bpf: disable and remove registers chain based liveness

2025-09-19T16:27:23+00:00

Remove register chain based liveness tracking: - struct bpf_reg_state->{parent,live} fields are no longer needed; - REG_LIVE_WRITTEN marks are superseded by bpf_mark_stack_write() calls; - mark_reg_read() calls are superseded by bpf_mark_stack_read(); - log.c:print_liveness() is superseded by logging in liveness.c; - propagate_liveness() is superseded by bpf_update_live_stack(); - no need to establish register chains in is_state_visited() anymore; - fix a bunch of tests expecting "_w" suffixes in verifier log messages. Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250918-callchain-sensitive-liveness-v3-9-c3cd27bacc60@gmail.com Signed-off-by: Alexei Starovoitov

bpf: Enforce RCU protection for KF_RCU_PROTECTED

2025-09-18T22:36:17+00:00

Currently, KF_RCU_PROTECTED only applies to iterator APIs and that too in a convoluted fashion: the presence of this flag on the kfunc is used to set MEM_RCU in iterator type, and the lack of RCU protection results in an error only later, once next() or destroy() methods are invoked on the iterator. While there is no bug, this is certainly a bit unintuitive, and makes the enforcement of the flag iterator specific. In the interest of making this flag useful for other upcoming kfuncs, e.g. scx_bpf_cpu_curr() [0][1], add enforcement for invoking the kfunc in an RCU critical section in general. This would also mean that iterator APIs using KF_RCU_PROTECTED will error out earlier, instead of throwing an error for lack of RCU CS protection when next() or destroy() methods are invoked. In addition to this, if the kfuncs tagged KF_RCU_PROTECTED return a pointer value, ensure that this pointer value is only usable in an RCU critical section. There might be edge cases where the return value is special and doesn't need to imply MEM_RCU semantics, but in general, the assumption should hold for the majority of kfuncs, and we can revisit things if necessary later. [0]: https://lore.kernel.org/all/20250903212311.369697-3-christian.loehle@arm.com [1]: https://lore.kernel.org/all/20250909195709.92669-1-arighi@nvidia.com Tested-by: Andrea Righi Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250917032755.4068726-2-memxor@gmail.com Signed-off-by: Alexei Starovoitov