[PATCH bpf-next v2 0/2] bpf: use vrealloc() in bpf_patch_insn_data()

[Eduard Zingerman <eddyz87@gmail.com>]

Function bpf_patch_insn_data() uses vzalloc/vfree pair to allocate
memory for updated insn_aux_data. These operations are expensive for
big programs where a lot of rewrites happen, e.g. for pyperf180 test
case. The pair can be replaced with a call to vrealloc in order to
reduce the number of actual memory allocations.

Perf stat w/o this patch:

  $ perf stat -B --all-kernel -r10 -- ./veristat -q pyperf180.bpf.o
    ...
           2201.25 msec task-clock                       #    0.973 CPUs utilized               ( +-  2.20% )
               188      context-switches                 #   85.406 /sec                        ( +-  9.29% )
                15      cpu-migrations                   #    6.814 /sec                        ( +-  5.64% )
                 5      page-faults                      #    2.271 /sec                        ( +-  3.27% )
        4315057974      instructions                     #    1.28  insn per cycle
                                                  #    0.33  stalled cycles per insn     ( +-  0.03% )
        3366141387      cycles                           #    1.529 GHz                         ( +-  0.21% )
        1420810964      stalled-cycles-frontend          #   42.21% frontend cycles idle        ( +-  0.23% )
        1049956791      branches                         #  476.981 M/sec                       ( +-  0.03% )
          60591781      branch-misses                    #    5.77% of all branches             ( +-  0.07% )

            2.2632 +- 0.0527 seconds time elapsed  ( +-  2.33% )

Perf stat with this patch:

           1227.15 msec task-clock                       #    0.963 CPUs utilized               ( +-  2.27% )
               170      context-switches                 #  138.532 /sec                        ( +-  5.62% )
                 2      cpu-migrations                   #    1.630 /sec                        ( +- 33.37% )
                 5      page-faults                      #    4.074 /sec                        ( +-  4.47% )
        3312254304      instructions                     #    2.17  insn per cycle
                                                  #    0.15  stalled cycles per insn     ( +-  0.03% )
        1528944717      cycles                           #    1.246 GHz                         ( +-  0.31% )
         501475146      stalled-cycles-frontend          #   32.80% frontend cycles idle        ( +-  0.50% )
         730426891      branches                         #  595.222 M/sec                       ( +-  0.03% )
          17372363      branch-misses                    #    2.38% of all branches             ( +-  0.16% )

            1.2744 +- 0.0301 seconds time elapsed  ( +-  2.36% )

Changelog:
v1: https://lore.kernel.org/bpf/20250806200928.3080531-1-eddyz87@gmail.com/T/#t
v1 -> v2:
- added missing memset(0) in adjust_insn_aux_data(),
  this fixes CI failure reported in [1].

[1] https://github.com/kernel-patches/bpf/actions/runs/16787563163/job/47542309875

Eduard Zingerman (2):
  bpf: removed unused 'env' parameter from is_reg64 and insn_has_def32
  bpf: use realloc in bpf_patch_insn_data

 kernel/bpf/verifier.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

-- 
2.47.3