mirror of https://github.com/torvalds/linux.git
39ab20647d
-----BEGIN PGP SIGNATURE----- iIsEABYIADMWIQTFp0I1jqZrAX+hPRXbK58LschIgwUCZw1/jBUcZGFuaWVsQGlv Z2VhcmJveC5uZXQACgkQ2yufC7HISIO/ZwEAuAVkRgyuC0njVV9PyT7EbZqxHjY+ 10v6I6XR8vWmILABALrTIR9wTOyBVgmZzW7AUq8wiFv9FSZmhJfp1KxPdNYA =L6hT -----END PGP SIGNATURE----- Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== pull-request: bpf-next 2024-10-14 The following pull-request contains BPF updates for your *net-next* tree. We've added 21 non-merge commits during the last 18 day(s) which contain a total of 21 files changed, 1185 insertions(+), 127 deletions(-). The main changes are: 1) Put xsk sockets on a struct diet and add various cleanups. Overall, this helps to bump performance by 12% for some workloads, from Maciej Fijalkowski. 2) Extend BPF selftests to increase coverage of XDP features in combination with BPF cpumap, from Alexis Lothoré (eBPF Foundation). 3) Extend netkit with an option to delegate skb->{mark,priority} scrubbing to its BPF program, from Daniel Borkmann. 4) Make the bpf_get_netns_cookie() helper available also to tc(x) BPF programs, from Mahe Tardy. 5) Extend BPF selftests covering a BPF program setting socket options per MPTCP subflow, from Geliang Tang and Nicolas Rybowski. bpf-next-for-netdev * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (21 commits) xsk: Use xsk_buff_pool directly for cq functions xsk: Wrap duplicated code to function xsk: Carry a copy of xdp_zc_max_segs within xsk_buff_pool xsk: Get rid of xdp_buff_xsk::orig_addr xsk: s/free_list_node/list_node/ xsk: Get rid of xdp_buff_xsk::xskb_list_node selftests/bpf: check program redirect in xdp_cpumap_attach selftests/bpf: make xdp_cpumap_attach keep redirect prog attached selftests/bpf: fix bpf_map_redirect call for cpu map test selftests/bpf: add tcx netns cookie tests bpf: add get_netns_cookie helper to tc programs selftests/bpf: add missing header include for htons selftests/bpf: Extend netkit tests to validate skb meta data tools: Sync if_link.h uapi tooling header netkit: Add add netkit scrub support to rt_link.yaml netkit: Simplify netkit mode over to use NLA_POLICY_MAX netkit: Add option for scrubbing skb meta data bpf: Remove unused macro selftests/bpf: Add mptcp subflow subtest selftests/bpf: Add getsockopt to inspect mptcp subflow ... ==================== Link: https://patch.msgid.link/20241014211110.16562-1-daniel@iogearbox.net Signed-off-by: Paolo Abeni <pabeni@redhat.com> |
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README
Why we want a copy of kernel headers in tools?
==============================================
There used to be no copies, with tools/ code using kernel headers
directly. From time to time tools/perf/ broke due to legitimate kernel
hacking. At some point Linus complained about such direct usage. Then we
adopted the current model.
The way these headers are used in perf are not restricted to just
including them to compile something.
There are sometimes used in scripts that convert defines into string
tables, etc, so some change may break one of these scripts, or new MSRs
may use some different #define pattern, etc.
E.g.:
$ ls -1 tools/perf/trace/beauty/*.sh | head -5
tools/perf/trace/beauty/arch_errno_names.sh
tools/perf/trace/beauty/drm_ioctl.sh
tools/perf/trace/beauty/fadvise.sh
tools/perf/trace/beauty/fsconfig.sh
tools/perf/trace/beauty/fsmount.sh
$
$ tools/perf/trace/beauty/fadvise.sh
static const char *fadvise_advices[] = {
[0] = "NORMAL",
[1] = "RANDOM",
[2] = "SEQUENTIAL",
[3] = "WILLNEED",
[4] = "DONTNEED",
[5] = "NOREUSE",
};
$
The tools/perf/check-headers.sh script, part of the tools/ build
process, points out changes in the original files.
So its important not to touch the copies in tools/ when doing changes in
the original kernel headers, that will be done later, when
check-headers.sh inform about the change to the perf tools hackers.
Another explanation from Ingo Molnar:
It's better than all the alternatives we tried so far:
- Symbolic links and direct #includes: this was the original approach but
was pushed back on from the kernel side, when tooling modified the
headers and broke them accidentally for kernel builds.
- Duplicate self-defined ABI headers like glibc: double the maintenance
burden, double the chance for mistakes, plus there's no tech-driven
notification mechanism to look at new kernel side changes.
What we are doing now is a third option:
- A software-enforced copy-on-write mechanism of kernel headers to
tooling, driven by non-fatal warnings on the tooling side build when
kernel headers get modified:
Warning: Kernel ABI header differences:
diff -u tools/include/uapi/drm/i915_drm.h include/uapi/drm/i915_drm.h
diff -u tools/include/uapi/linux/fs.h include/uapi/linux/fs.h
diff -u tools/include/uapi/linux/kvm.h include/uapi/linux/kvm.h
...
The tooling policy is to always pick up the kernel side headers as-is,
and integate them into the tooling build. The warnings above serve as a
notification to tooling maintainers that there's changes on the kernel
side.
We've been using this for many years now, and it might seem hacky, but
works surprisingly well.