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In order to express test cases that use bpf_tail_call() intrinsic it
is necessary to have several programs to be loaded at a time.
This commit adds __auxiliary annotation to the set of annotations
supported by test_loader.c. Programs marked as auxiliary are always
loaded but are not treated as a separate test.
For example:
void dummy_prog1(void);
struct {
__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
__uint(max_entries, 4);
__uint(key_size, sizeof(int));
__array(values, void (void));
} prog_map SEC(".maps") = {
.values = {
[0] = (void *) &dummy_prog1,
},
};
SEC("tc")
__auxiliary
__naked void dummy_prog1(void) {
asm volatile ("r0 = 42; exit;");
}
SEC("tc")
__description("reference tracking: check reference or tail call")
__success __retval(0)
__naked void check_reference_or_tail_call(void)
{
asm volatile (
"r2 = %[prog_map] ll;"
"r3 = 0;"
"call %[bpf_tail_call];"
"r0 = 0;"
"exit;"
:: __imm(bpf_tail_call),
: __clobber_all);
}
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230421174234.2391278-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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When a test case is annotated with __retval tag the test_loader engine
would use libbpf's bpf_prog_test_run_opts() to do a test run of the
program and compare retvals.
This commit allows to perform arbitrary actions on bpf object right
before test loader invokes bpf_prog_test_run_opts(). This could be
used to setup some state for program execution, e.g. fill some maps.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230420232317.2181776-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Florian Westphal found a bug in and suggested a fix for test_loader.c
processing of __retval tag. Because of this bug the function
test_loader.c:do_prog_test_run() never executed and all __retval test
tags were ignored.
If this bug is fixed a number of test cases from
progs/verifier_array_access.c fail with retval not matching the
expected value. This test was recently converted to use test_loader.c
and inline assembly in [1]. When doing the conversion I missed the
important detail of test_verifier.c operation: when it creates
fixup_map_array_ro, fixup_map_array_wo and fixup_map_array_small it
populates these maps with a dummy record.
Disabling the __retval checks for the affected verifier_array_access
in this commit to avoid false-postivies in any potential bisects.
The issue is addressed in the next patch.
I verified that the __retval tags are now respected by changing
expected return values for all tests annotated with __retval, and
checking that these tests started to fail.
[1] https://lore.kernel.org/bpf/20230325025524.144043-1-eddyz87@gmail.com/
Fixes: 19a8e06f5f91 ("selftests/bpf: Tests execution support for test_loader.c")
Reported-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/bpf/f4c4aee644425842ee6aa8edf1da68f0a8260e7c.camel@gmail.com/T/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230420232317.2181776-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Extends test_loader.c:test_loader__run_subtests() by allowing to
execute BPF_PROG_TEST_RUN bpf command for selected programs.
This is similar to functionality provided by test_verifier.
Adds the following new attributes controlling test_loader behavior:
__retval(...)
__retval_unpriv(...)
* If any of these attributes is present, the annotated program would
be executed using libbpf's bpf_prog_test_run_opts() function.
* If __retval is present, the test run would be done for program
loaded in privileged mode.
* If __retval_unpriv is present, the test run would be done for
program loaded in unprivileged mode.
* To mimic test_verifier behavior, the actual run is initiated in
privileged mode.
* The value returned by a test run is compared against retval
parameter.
The retval attribute takes one of the following parameters:
- a decimal number
- a hexadecimal number (must start from '0x')
- any of a three special literals (provided for compatibility with
test_verifier):
- INT_MIN
- POINTER_VALUE
- TEST_DATA_LEN
An example of the attribute usage:
SEC("socket")
__description("return 42")
__success __success_unpriv __retval(42)
__naked void the_42_test(void)
{
asm volatile (" \
r0 = 42; \
exit; \
" ::: __clobber_all);
}
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230325025524.144043-5-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Extends test_loader.c:test_loader__run_subtests() by allowing to
execute tests in unprivileged mode, similar to test_verifier.c.
Adds the following new attributes controlling test_loader behavior:
__msg_unpriv
__success_unpriv
__failure_unpriv
* If any of these attributes is present the test would be loaded in
unprivileged mode.
* If only "privileged" attributes are present the test would be loaded
only in privileged mode.
* If both "privileged" and "unprivileged" attributes are present the
test would be loaded in both modes.
* If test has to be executed in both modes, __msg(text) is specified
and __msg_unpriv is not specified the behavior is the same as if
__msg_unpriv(text) is specified.
* For test filtering purposes the name of the program loaded in
unprivileged mode is derived from the usual program name by adding
`@unpriv' suffix.
Also adds attribute '__description'. This attribute specifies text to
be used instead of a program name for display and filtering purposes.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230325025524.144043-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Change test_loader.c:run_subtest() behavior to show BPF program name
when test spec for that program can't be parsed.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230325025524.144043-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Extend __flag attribute by allowing to specify one of the following:
* BPF_F_STRICT_ALIGNMENT
* BPF_F_ANY_ALIGNMENT
* BPF_F_TEST_RND_HI32
* BPF_F_TEST_STATE_FREQ
* BPF_F_SLEEPABLE
* BPF_F_XDP_HAS_FRAGS
* Some numeric value
Extend __msg attribute by allowing to specify multiple exepcted messages.
All messages are expected to be present in the verifier log in the
order of application.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230301175417.3146070-2-eddyz87@gmail.com
[ Eduard: added commit message, formatting, comments ]
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It's become a common pattern to have a collection of small BPF programs
in one BPF object file, each representing one test case. On user-space
side of such tests we maintain a table of program names and expected
failure or success, along with optional expected verifier log message.
This works, but each set of tests reimplement this mundane code over and
over again, which is a waste of time for anyone trying to add a new set
of tests. Furthermore, it's quite error prone as it's way too easy to miss
some entries in these manually maintained test tables (as evidences by
dynptr_fail tests, in which ringbuf_release_uninit_dynptr subtest was
accidentally missed; this is fixed in next patch).
So this patch implements generic test_loader, which accepts skeleton
name and handles the rest of details: opens and loads BPF object file,
making sure each program is tested in isolation. Optionally each test
case can specify expected BPF verifier log message. In case of failure,
tester makes sure to report verifier log, but it also reports verifier
log in verbose mode unconditionally.
Now, the interesting deviation from existing custom implementations is
the use of btf_decl_tag attribute to specify expected-to-fail vs
expected-to-succeed markers and, optionally, expected log message
directly next to BPF program source code, eliminating the need to
manually create and update table of tests.
We define few macros wrapping btf_decl_tag with a convention that all
values of btf_decl_tag start with "comment:" prefix, and then utilizing
a very simple "just_some_text_tag" or "some_key_name=<value>" pattern to
define things like expected success/failure, expected verifier message,
extra verifier log level (if necessary). This approach is demonstrated
by next patch in which two existing sets of failure tests are converted.
Tester supports both expected-to-fail and expected-to-succeed programs,
though this patch set didn't convert any existing expected-to-succeed
programs yet, as existing tests couple BPF program loading with their
further execution through attach or test_prog_run. One way to allow
testing scenarios like this would be ability to specify custom callback,
executed for each successfully loaded BPF program. This is left for
follow up patches, after some more analysis of existing test cases.
This test_loader is, hopefully, a start of a test_verifier-like runner,
but integrated into test_progs infrastructure. It will allow much better
"user experience" of defining low-level verification tests that can take
advantage of all the libbpf-provided nicety features on BPF side: global
variables, declarative maps, etc. All while having a choice of defining
it in C or as BPF assembly (through __attribute__((naked)) functions and
using embedded asm), depending on what makes most sense in each
particular case. This will be explored in follow up patches as well.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221207201648.2990661-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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