Add bpf_for_each(), bpf_for(), and bpf_repeat() macros that make writing
open-coded iterator-based loops much more convenient and natural. These
macros utilize cleanup attribute to ensure proper destruction of the
iterator and thanks to that manage to provide the ergonomics that is
very close to C language's for() construct. Typical loop would look like:
int i;
int arr[N];
bpf_for(i, 0, N) {
/* verifier will know that i >= 0 && i < N, so could be used to
* directly access array elements with no extra checks
*/
arr[i] = i;
}
bpf_repeat() is very similar, but it doesn't expose iteration number and
is meant as a simple "repeat action N times" loop:
bpf_repeat(N) { /* whatever, N times */ }
Note that `break` and `continue` statements inside the {} block work as
expected.
bpf_for_each() is a generalization over any kind of BPF open-coded
iterator allowing to use for-each-like approach instead of calling
low-level bpf_iter_<type>_{new,next,destroy}() APIs explicitly. E.g.:
struct cgroup *cg;
bpf_for_each(cgroup, cg, some, input, args) {
/* do something with each cg */
}
would call (not-yet-implemented) bpf_iter_cgroup_{new,next,destroy}()
functions to form a loop over cgroups, where `some, input, args` are
passed verbatim into constructor as
bpf_iter_cgroup_new(&it, some, input, args).
As a first demonstration, add pyperf variant based on the bpf_for() loop.
Also clean up a few tests that either included bpf_misc.h header
unnecessarily from the user-space, which is unsupported, or included it
before any common types are defined (and thus leading to unnecessary
compilation warnings, potentially).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230308184121.1165081-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF object files are, in a way, the final artifact produced as part of
the ahead-of-time compilation process. That makes them somewhat special
compared to "regular" object files, which are a intermediate build
artifacts that can typically be removed safely. As such, it can make
sense to name them differently to make it easier to spot this difference
at a glance.
Among others, libbpf-bootstrap [0] has established the extension .bpf.o
for BPF object files. It seems reasonable to follow this example and
establish the same denomination for selftest build artifacts. To that
end, this change adjusts the corresponding part of the build system and
the test programs loading BPF object files to work with .bpf.o files.
[0] https://github.com/libbpf/libbpf-bootstrap
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220901222253.1199242-1-deso@posteo.net
Migrate all the selftests that were still using bpf_prog_load_xattr().
Few are converted to skeleton, others will use bpf_object__open_file()
API.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211201232824.3166325-7-andrii@kernel.org
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
./test_progs-no_alu32 -vv -t twfw
Before the 64-bit_into_32-bit fix:
19: (25) if r1 > 0x3f goto pc+6
R1_w=inv(id=0,umax_value=63,var_off=(0x0; 0xff),s32_max_value=255,u32_max_value=255)
and eventually:
invalid access to map value, value_size=8 off=7 size=8
R6 max value is outside of the allowed memory range
libbpf: failed to load object 'no_alu32/twfw.o'
After the fix:
19: (25) if r1 > 0x3f goto pc+6
R1_w=inv(id=0,umax_value=63,var_off=(0x0; 0x3f))
verif_twfw:OK
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-3-alexei.starovoitov@gmail.com
Instead of using subtests in bpf_verif_scale selftest, turn each scale
sub-test into its own test. Each subtest is compltely independent and
just reuses a bit of common test running logic, so the conversion is
trivial. For convenience, keep all of BPF verifier scale tests in one
file.
This conversion shaves off a significant amount of time when running
test_progs in parallel mode. E.g., just running scale tests (-t verif_scale):
BEFORE
======
Summary: 24/0 PASSED, 0 SKIPPED, 0 FAILED
real 0m22.894s
user 0m0.012s
sys 0m22.797s
AFTER
=====
Summary: 24/0 PASSED, 0 SKIPPED, 0 FAILED
real 0m12.044s
user 0m0.024s
sys 0m27.869s
Ten second saving right there. test_progs -j is not yet ready to be
turned on by default, unfortunately, and some tests fail almost every
time, but this is a good improvement nevertheless. Ignoring few
failures, here is sequential vs parallel run times when running all
tests now:
SEQUENTIAL
==========
Summary: 206/953 PASSED, 4 SKIPPED, 0 FAILED
real 1m5.625s
user 0m4.211s
sys 0m31.650s
PARALLEL
========
Summary: 204/952 PASSED, 4 SKIPPED, 2 FAILED
real 0m35.550s
user 0m4.998s
sys 0m39.890s
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211022223228.99920-5-andrii@kernel.org
The original bcc pull request https://github.com/iovisor/bcc/pull/3270 exposed
a verifier failure with Clang 12/13 while Clang 4 works fine.
Further investigation exposed two issues:
Issue 1: LLVM may generate code which uses less refined value. The issue is
fixed in LLVM patch: https://reviews.llvm.org/D97479
Issue 2: Spills with initial value 0 are marked as precise which makes later
state pruning less effective. This is my rough initial analysis and
further investigation is needed to find how to improve verifier
pruning in such cases.
With the above LLVM patch, for the new loop6.c test, which has smaller loop
bound compared to original test, I got:
$ test_progs -s -n 10/16
...
stack depth 64
processed 390735 insns (limit 1000000) max_states_per_insn 87
total_states 8658 peak_states 964 mark_read 6
#10/16 loop6.o:OK
Use the original loop bound, i.e., commenting out "#define WORKAROUND", I got:
$ test_progs -s -n 10/16
...
BPF program is too large. Processed 1000001 insn
stack depth 64
processed 1000001 insns (limit 1000000) max_states_per_insn 91
total_states 23176 peak_states 5069 mark_read 6
...
#10/16 loop6.o:FAIL
The purpose of this patch is to provide a regression test for the above LLVM fix
and also provide a test case for further analyzing the verifier pruning issue.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Zhenwei Pi <pizhenwei@bytedance.com>
Link: https://lore.kernel.org/bpf/20210226223810.236472-1-yhs@fb.com
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
test results:
pyperf50 with always_inlined the same function five times: processed 46378 insns
pyperf50 with global function: processed 6102 insns
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200110064124.1760511-5-ast@kernel.org
Add exra level of verboseness, activated by -vvv argument. When -vv is
specified, verbose libbpf and verifier log (level 1) is output, even for
successful tests. With -vvv, verifier log goes to level 2.
This is extremely useful to debug verifier failures, as well as just see the
state and flow of verification. Before this, you'd have to go and modify
load_program()'s source code inside libbpf to specify extra log_level flags,
which is suboptimal to say the least.
Currently -vv and -vvv triggering verifier output is integrated into
test_stub's bpf_prog_load as well as bpf_verif_scale.c tests.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191120003548.4159797-1-andriin@fb.com
Now that we have a global per-test/per-environment state, there
is no longer need to have global fail/success counters (and there
is no need to save/get the diff before/after the test).
Introduce CHECK_FAIL macro (suggested by Andrii) and covert existing tests
to it. CHECK_FAIL uses new test__fail() to record the failure.
Cc: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Now that test__printf is a simple wraper around printf, let's drop it
(and test__vprintf as well).
Cc: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a test with multiple exit conditions.
It's not an infinite loop only when the verifier can properly track
all math on variable 'i' through all possible ways of executing this loop.
barrier()s are needed to disable llvm optimization that combines multiple
branches into fewer branches.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Add a test that returns a 'random' number between [0, 2^20)
If state pruning is not working correctly for loop body the number of
processed insns will be 2^20 * num_of_insns_in_loop_body and the program
will be rejected.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
This patch changes how test output is printed out. By default, if test
had no errors, the only output will be a single line with test number,
name, and verdict at the end, e.g.:
#31 xdp:OK
If test had any errors, all log output captured during test execution
will be output after test completes.
It's possible to force output of log with `-v` (`--verbose`) option, in
which case output won't be buffered and will be output immediately.
To support this, individual tests are required to use helper methods for
logging: `test__printf()` and `test__vprintf()`.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Make test_progs test runner own libbpf logging. Also introduce two
levels of verbosity: -v and -vv. First one will be used in subsequent
patches to enable test log output always. Second one increases verbosity
level of libbpf logging further to include debug output as well.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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>
The previous libbpf patch allows user to specify "prog_flags" to bpf
program load APIs. To enable high 32-bit randomization for a test, we need
to set BPF_F_TEST_RND_HI32 in "prog_flags".
To enable such randomization for all tests, we need to make sure all places
are passing BPF_F_TEST_RND_HI32. Changing them one by one is not
convenient, also, it would be better if a test could be switched to
"normal" running mode without code change.
Given the program load APIs used across bpf selftests are mostly:
bpf_prog_load: load from file
bpf_load_program: load from raw insns
A test_stub.c is implemented for bpf seltests, it offers two functions for
testing purpose:
bpf_prog_test_load
bpf_test_load_program
The are the same as "bpf_prog_load" and "bpf_load_program", except they
also set BPF_F_TEST_RND_HI32. Given *_xattr functions are the APIs to
customize any "prog_flags", it makes little sense to put these two
functions into libbpf.
Then, the following CFLAGS are passed to compilations for host programs:
-Dbpf_prog_load=bpf_prog_test_load
-Dbpf_load_program=bpf_test_load_program
They migrate the used load APIs to the test version, hence enable high
32-bit randomization for these tests without changing source code.
Besides all these, there are several testcases are using
"bpf_prog_load_attr" directly, their call sites are updated to pass
BPF_F_TEST_RND_HI32.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a snippet of pyperf bpf program used to collect python stack traces
as a scale test for the verifier.
At 189 loop iterations llvm 9.0 starts ignoring '#pragma unroll'
and generates partially unrolled loop instead.
Hence use 50, 100, and 180 loop iterations to stress test.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
There are a few tests which call bpf_object__close on uninitialized
bpf_object*, which may segfault. Explicitly zero-initialise these pointers
to avoid this.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add 3 basic tests that stress verifier scalability.
test_verif_scale1.c calls non-inlined jhash() function 90 times on
different position in the packet.
This test simulates network packet parsing.
jhash function is ~140 instructions and main program is ~1200 insns.
test_verif_scale2.c force inlines jhash() function 90 times.
This program is ~15k instructions long.
test_verif_scale3.c calls non-inlined jhash() function 90 times on
But this time jhash has to process 32-bytes from the packet
instead of 14-bytes in tests 1 and 2.
jhash function is ~230 insns and main program is ~1200 insns.
$ test_progs -s
can be used to see verifier stats.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
