[RFC PATCH 0/3] enable bpf_prog_pack allocator for powerpc

[Hari Bathini]

Most BPF programs are small, but they consume a page each. For systems
with busy traffic and many BPF programs, this may also add significant
pressure on instruction TLB. High iTLB pressure usually slows down the
whole system causing visible performance degradation for production
workloads.

bpf_prog_pack, a customized allocator that packs multiple bpf programs
into preallocated memory chunks, was proposed [1] to address it. This
series extends this support on powerpc.

Patches 1 & 2 add the arch specific functions needed to support this
feature. Patch 3 enables the support for powerpc. The last patch
ensures cleanup is handled racefully.

Tested the changes successfully on a PowerVM. patch_instruction(),
needed for bpf_arch_text_copy(), is failing for ppc32. Debugging it.
Posting the patches in the meanwhile for feedback on these changes.

[1] https://lore.kernel.org/bpf/20220204185742.271030-1-song@kernel.org/

Hari Bathini (3):
  powerpc/bpf: implement bpf_arch_text_copy
  powerpc/bpf: implement bpf_arch_text_invalidate for bpf_prog_pack
  powerpc/bpf: use bpf_jit_binary_pack_[alloc|finalize|free]

 arch/powerpc/net/bpf_jit.h        |  18 +--
 arch/powerpc/net/bpf_jit_comp.c   | 194 ++++++++++++++++++++++++------
 arch/powerpc/net/bpf_jit_comp32.c |  26 ++--
 arch/powerpc/net/bpf_jit_comp64.c |  32 ++---
 4 files changed, 198 insertions(+), 72 deletions(-)

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2.37.3