netdev - [PATCH v2 bpf-next 0/4] bpf: Make the verifier recognize llvm register allocation patterns.

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Message-Id: <20201009011240.48506-1-alexei.starovoitov@gmail.com>
Date:   Thu,  8 Oct 2020 18:12:36 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     davem@...emloft.net
Cc:     daniel@...earbox.net, john.fastabend@...il.com,
        netdev@...r.kernel.org, bpf@...r.kernel.org, kernel-team@...com
Subject: [PATCH v2 bpf-next 0/4] bpf: Make the verifier recognize llvm register allocation patterns.

From: Alexei Starovoitov <ast@...nel.org>

v1->v2:
- fixed 32-bit mov issue spotted by John.
- allowed r2=r1; r3=r2; sequence as suggested by John.
- added comments, acks, more tests.

Make two verifier improvements:
- The llvm register allocator may use two different registers representing the
  same virtual register. Teach the verifier to recognize that.
- Track bounded scalar spill/fill.

The profiler[123] test in patch 3 will fail to load without patches 1 and 2.
The profiler[23] test may fail to load on older llvm due to speculative
code motion nd instruction combining optimizations that are fixed in
https://reviews.llvm.org/D85570

Alexei Starovoitov (3):
  bpf: Propagate scalar ranges through register assignments.
  selftests/bpf: Add profiler test
  selftests/bpf: Asm tests for the verifier regalloc tracking.

Yonghong Song (1):
  bpf: Track spill/fill of bounded scalars.

 kernel/bpf/verifier.c                         |  66 +-
 tools/testing/selftests/bpf/README.rst        |  38 +
 .../testing/selftests/bpf/prog_tests/align.c  |  16 +-
 .../selftests/bpf/prog_tests/test_profiler.c  |  72 ++
 tools/testing/selftests/bpf/progs/profiler.h  | 177 ++++
 .../selftests/bpf/progs/profiler.inc.h        | 969 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/profiler1.c |   6 +
 tools/testing/selftests/bpf/progs/profiler2.c |   6 +
 tools/testing/selftests/bpf/progs/profiler3.c |   6 +
 .../bpf/verifier/direct_packet_access.c       |   2 +-
 .../testing/selftests/bpf/verifier/regalloc.c | 243 +++++
 11 files changed, 1591 insertions(+), 10 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_profiler.c
 create mode 100644 tools/testing/selftests/bpf/progs/profiler.h
 create mode 100644 tools/testing/selftests/bpf/progs/profiler.inc.h
 create mode 100644 tools/testing/selftests/bpf/progs/profiler1.c
 create mode 100644 tools/testing/selftests/bpf/progs/profiler2.c
 create mode 100644 tools/testing/selftests/bpf/progs/profiler3.c
 create mode 100644 tools/testing/selftests/bpf/verifier/regalloc.c

-- 
2.23.0