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This patch tests bpf_loop in pyperf and strobemeta, and measures the
verifier performance of replacing the traditional for loop
with bpf_loop.
The results are as follows:
~strobemeta~
Baseline
verification time 6808200 usec
stack depth 496
processed 554252 insns (limit 1000000) max_states_per_insn 16
total_states 15878 peak_states 13489 mark_read 3110
#192 verif_scale_strobemeta:OK (unrolled loop)
Using bpf_loop
verification time 31589 usec
stack depth 96+400
processed 1513 insns (limit 1000000) max_states_per_insn 2
total_states 106 peak_states 106 mark_read 60
#193 verif_scale_strobemeta_bpf_loop:OK
~pyperf600~
Baseline
verification time 29702486 usec
stack depth 368
processed 626838 insns (limit 1000000) max_states_per_insn 7
total_states 30368 peak_states 30279 mark_read 748
#182 verif_scale_pyperf600:OK (unrolled loop)
Using bpf_loop
verification time 148488 usec
stack depth 320+40
processed 10518 insns (limit 1000000) max_states_per_insn 10
total_states 705 peak_states 517 mark_read 38
#183 verif_scale_pyperf600_bpf_loop:OK
Using the bpf_loop helper led to approximately a 99% decrease
in the verification time and in the number of instructions.
Signed-off-by: Joanne Koong <joannekoong@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211130030622.4131246-4-joannekoong@fb.com
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Previous fix aded bpf_clamp_umax() helper use to re-validate boundaries.
While that works correctly, it introduces more branches, which blows up
past 1 million instructions in no-alu32 variant of strobemeta selftests.
Switching len variable from u32 to u64 also fixes the issue and reduces
the number of validated instructions, so use that instead. Fix this
patch and bpf_clamp_umax() removed, both alu32 and no-alu32 selftests
pass.
Fixes: 0133c20480b1 ("selftests/bpf: Fix strobemeta selftest regression")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211101230118.1273019-1-andrii@kernel.org
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After most recent nightly Clang update strobemeta selftests started
failing with the following error (relevant portion of assembly included):
1624: (85) call bpf_probe_read_user_str#114
1625: (bf) r1 = r0
1626: (18) r2 = 0xfffffffe
1628: (5f) r1 &= r2
1629: (55) if r1 != 0x0 goto pc+7
1630: (07) r9 += 104
1631: (6b) *(u16 *)(r9 +0) = r0
1632: (67) r0 <<= 32
1633: (77) r0 >>= 32
1634: (79) r1 = *(u64 *)(r10 -456)
1635: (0f) r1 += r0
1636: (7b) *(u64 *)(r10 -456) = r1
1637: (79) r1 = *(u64 *)(r10 -368)
1638: (c5) if r1 s< 0x1 goto pc+778
1639: (bf) r6 = r8
1640: (0f) r6 += r7
1641: (b4) w1 = 0
1642: (6b) *(u16 *)(r6 +108) = r1
1643: (79) r3 = *(u64 *)(r10 -352)
1644: (79) r9 = *(u64 *)(r10 -456)
1645: (bf) r1 = r9
1646: (b4) w2 = 1
1647: (85) call bpf_probe_read_user_str#114
R1 unbounded memory access, make sure to bounds check any such access
In the above code r0 and r1 are implicitly related. Clang knows that,
but verifier isn't able to infer this relationship.
Yonghong Song narrowed down this "regression" in code generation to
a recent Clang optimization change ([0]), which for BPF target generates
code pattern that BPF verifier can't handle and loses track of register
boundaries.
This patch works around the issue by adding an BPF assembly-based helper
that helps to prove to the verifier that upper bound of the register is
a given constant by controlling the exact share of generated BPF
instruction sequence. This fixes the immediate issue for strobemeta
selftest.
[0] https://github.com/llvm/llvm-project/commit/acabad9ff6bf13e00305d9d8621ee8eafc1f8b08
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211029182907.166910-1-andrii@kernel.org
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Add use of non-inlined subprogs to few bigger selftests to excercise libbpf's
bpf2bpf handling logic. Also split l4lb_all selftest into two sub-tests.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200903203542.15944-13-andriin@fb.com
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Fix all selftests to include libbpf header files with the bpf/ prefix, to
be consistent with external users of the library. Also ensure that all
includes of exported libbpf header files (those that are exported on 'make
install' of the library) use bracketed includes instead of quoted.
To not break the build, keep the old include path until everything has been
changed to the new one; a subsequent patch will remove that.
Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157952560568.1683545.9649335788846513446.stgit@toke.dk
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Use probe read *_{kernel,user}{,_str}() helpers instead of bpf_probe_read()
or bpf_probe_read_user_str() for program tests where appropriate.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/4a61d4b71ce3765587d8ef5cb93afa18515e5b3e.1572649915.git.daniel@iogearbox.net
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Some recent changes in latest Clang started causing the following
warning when unrolling strobemeta test case main loop:
progs/strobemeta.h:416:2: warning: loop not unrolled: the optimizer was
unable to perform the requested transformation; the transformation might
be disabled or specified as part of an unsupported transformation
ordering [-Wpass-failed=transform-warning]
This patch simplifies loop's exit condition to depend only on constant
max iteration number (STROBE_MAX_MAP_ENTRIES), while moving early
termination logic inside the loop body. The changes are equivalent from
program logic standpoint, but fixes the warning. It also appears to
improve generated BPF code, as it fixes previously failing non-unrolled
strobemeta test cases.
Cc: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Convert selftests that were originally left out and new ones added
recently to consistently use BTF-defined maps.
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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The progs for bpf selftests use several different notations to force
function inlining. Standardize to what most of them use,
static __always_inline.
Suggested-by: Song Liu <liu.song.a23@gmail.com>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Add a bunch of loop tests. Most of them are created by replacing
'#pragma unroll' with '#pragma clang loop unroll(disable)'
Several tests are artificially large:
/* partial unroll. llvm will unroll loop ~150 times.
* C loop count -> 600.
* Asm loop count -> 4.
* 16k insns in loop body.
* Total of 5 such loops. Total program size ~82k insns.
*/
"./pyperf600.o",
/* no unroll at all.
* C loop count -> 600.
* ASM loop count -> 600.
* ~110 insns in loop body.
* Total of 5 such loops. Total program size ~1500 insns.
*/
"./pyperf600_nounroll.o",
/* partial unroll. 19k insn in a loop.
* Total program size 20.8k insn.
* ~350k processed_insns
*/
"./strobemeta.o",
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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