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Subject[PATCH v4] docs: sysctl/kernel: document BPF entries
Based on the implementation in kernel/bpf/syscall.c,
kernel/bpf/trampoline.c, include/linux/filter.h, and the documentation
in bpftool-prog.rst.

Signed-off-by: Stephen Kitt <>

This patch is intended for docs-next, but I'd appreciate reviews from
BPF developers.

Changes since v3:
- moved back to docs-next.

Changes since v2:
- fixed "will disabled" typo.

Changes since v1:
- rebased on bpf-next instead of docs-next.

Documentation/admin-guide/sysctl/kernel.rst | 24 +++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 335696d3360d..88c51c0a5ce6 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -102,6 +102,20 @@ See the ``type_of_loader`` and ``ext_loader_ver`` fields in
:doc:`/x86/boot` for additional information.

+Controls whether the kernel should collect statistics on BPF programs
+(total time spent running, number of times run...). Enabling
+statistics causes a slight reduction in performance on each program
+run. The statistics can be seen using ``bpftool``.
+= ===================================
+0 Don't collect statistics (default).
+1 Collect statistics.
+= ===================================

@@ -1166,6 +1180,16 @@ NMI switch that most IA32 servers have fires unknown NMI up, for
example. If a system hangs up, try pressing the NMI switch.

+Writing 1 to this entry will disable unprivileged calls to ``bpf()``;
+once disabled, calling ``bpf()`` without ``CAP_SYS_ADMIN`` will return
+Once set, this can't be cleared.

base-commit: 7d3d3254adaa61cba896f71497f56901deb618e5

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