[PATCH v2 0/4] enable bpf_prog_pack allocator for powerpc

[Hari Bathini <hbathini@linux.ibm.com>]

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.

The first patch introduces patch_instructions() function to enable
patching more than one instruction at a time. This change showed
around 5X improvement in the time taken to run test_bpf test cases.
Patches 2 & 3 add the arch specific functions needed to support this
feature. Patch 4 enables the support for powerpc and ensures cleanup
is handled racefully. Tested the changes successfully.

[1] https://lore.kernel.org/bpf/20220204185742.271030-1-song@kernel.org/
[2] https://lore.kernel.org/all/20221110184303.393179-1-hbathini@linux.ibm.com/ 

Changes in v2:
* Introduced patch_instructions() to help with patching bpf programs.

Hari Bathini (4):
  powerpc/code-patching: introduce patch_instructions()
  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/include/asm/code-patching.h |   1 +
 arch/powerpc/lib/code-patching.c         | 151 ++++++++++++++++-------
 arch/powerpc/net/bpf_jit.h               |   7 +-
 arch/powerpc/net/bpf_jit_comp.c          | 142 ++++++++++++++++-----
 arch/powerpc/net/bpf_jit_comp32.c        |   4 +-
 arch/powerpc/net/bpf_jit_comp64.c        |   6 +-
 6 files changed, 226 insertions(+), 85 deletions(-)

-- 
2.39.2