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1) The test_lru_map and test_lru_dist fails building on my machine since
the sys/resource.h header is not included.
2) test_verifier fails in one test case where we try to call an invalid
function, since the verifier log output changed wrt printing function
names.
3) Current selftest suite code relies on sysconf(_SC_NPROCESSORS_CONF) for
retrieving the number of possible CPUs. This is broken at least in our
scenario and really just doesn't work.
glibc tries a number of things for retrieving _SC_NPROCESSORS_CONF.
First it tries equivalent of /sys/devices/system/cpu/cpu[0-9]* | wc -l,
if that fails, depending on the config, it either tries to count CPUs
in /proc/cpuinfo, or returns the _SC_NPROCESSORS_ONLN value instead.
If /proc/cpuinfo has some issue, it returns just 1 worst case. This
oddity is nothing new [1], but semantics/behaviour seems to be settled.
_SC_NPROCESSORS_ONLN will parse /sys/devices/system/cpu/online, if
that fails it looks into /proc/stat for cpuX entries, and if also that
fails for some reason, /proc/cpuinfo is consulted (and returning 1 if
unlikely all breaks down).
While that might match num_possible_cpus() from the kernel in some
cases, it's really not guaranteed with CPU hotplugging, and can result
in a buffer overflow since the array in user space could have too few
number of slots, and on perpcu map lookup, the kernel will write beyond
that memory of the value buffer.
William Tu reported such mismatches:
[...] The fact that sysconf(_SC_NPROCESSORS_CONF) != num_possible_cpu()
happens when CPU hotadd is enabled. For example, in Fusion when
setting vcpu.hotadd = "TRUE" or in KVM, setting ./qemu-system-x86_64
-smp 2, maxcpus=4 ... the num_possible_cpu() will be 4 and sysconf()
will be 2 [2]. [...]
Documentation/cputopology.txt says /sys/devices/system/cpu/possible
outputs cpu_possible_mask. That is the same as in num_possible_cpus(),
so first step would be to fix the _SC_NPROCESSORS_CONF calls with our
own implementation. Later, we could add support to bpf(2) for passing
a mask via CPU_SET(3), for example, to just select a subset of CPUs.
BPF samples code needs this fix as well (at least so that people stop
copying this). Thus, define bpf_num_possible_cpus() once in selftests
and import it from there for the sample code to avoid duplicating it.
The remaining sysconf(_SC_NPROCESSORS_CONF) in samples are unrelated.
After all three issues are fixed, the test suite runs fine again:
# make run_tests | grep self
selftests: test_verifier [PASS]
selftests: test_maps [PASS]
selftests: test_lru_map [PASS]
selftests: test_kmod.sh [PASS]
[1] https://www.sourceware.org/ml/libc-alpha/2011-06/msg00079.html
[2] https://www.mail-archive.com/netdev@vger.kernel.org/msg121183.html
Fixes: 3059303f59cf ("samples/bpf: update tracex[23] examples to use per-cpu maps")
Fixes: 86af8b4191d2 ("Add sample for adding simple drop program to link")
Fixes: df570f577231 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_ARRAY")
Fixes: e15596717948 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_HASH")
Fixes: ebb676daa1a3 ("bpf: Print function name in addition to function id")
Fixes: 5db58faf989f ("bpf: Add tests for the LRU bpf_htab")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: William Tu <u9012063@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch has some unit tests and a test_lru_dist.
The test_lru_dist reads in the numeric keys from a file.
The files used here are generated by a modified fio-genzipf tool
originated from the fio test suit. The sample data file can be
found here: https://github.com/iamkafai/bpf-lru
The zipf.* data files have 100k numeric keys and the key is also
ranged from 1 to 100k.
The test_lru_dist outputs the number of unique keys (nr_unique).
F.e. The following means, 61239 of them is unique out of 100k keys.
nr_misses means it cannot be found in the LRU map, so nr_misses
must be >= nr_unique. test_lru_dist also simulates a perfect LRU
map as a comparison:
[root@arch-fb-vm1 ~]# ~/devshare/fb-kernel/linux/samples/bpf/test_lru_dist \
/root/zipf.100k.a1_01.out 4000 1
...
test_parallel_lru_dist (map_type:9 map_flags:0x0):
task:0 BPF LRU: nr_unique:23093(/100000) nr_misses:31603(/100000)
task:0 Perfect LRU: nr_unique:23093(/100000 nr_misses:34328(/100000)
....
test_parallel_lru_dist (map_type:9 map_flags:0x2):
task:0 BPF LRU: nr_unique:23093(/100000) nr_misses:31710(/100000)
task:0 Perfect LRU: nr_unique:23093(/100000 nr_misses:34328(/100000)
[root@arch-fb-vm1 ~]# ~/devshare/fb-kernel/linux/samples/bpf/test_lru_dist \
/root/zipf.100k.a0_01.out 40000 1
...
test_parallel_lru_dist (map_type:9 map_flags:0x0):
task:0 BPF LRU: nr_unique:61239(/100000) nr_misses:67054(/100000)
task:0 Perfect LRU: nr_unique:61239(/100000 nr_misses:66993(/100000)
...
test_parallel_lru_dist (map_type:9 map_flags:0x2):
task:0 BPF LRU: nr_unique:61239(/100000) nr_misses:67068(/100000)
task:0 Perfect LRU: nr_unique:61239(/100000 nr_misses:66993(/100000)
LRU map has also been added to map_perf_test:
/* Global LRU */
[root@kerneltest003.31.prn1 ~]# for i in 1 4 8; do echo -n "$i cpus: "; \
./map_perf_test 16 $i | awk '{r += $3}END{print r " updates"}'; done
1 cpus: 2934082 updates
4 cpus: 7391434 updates
8 cpus: 6500576 updates
/* Percpu LRU */
[root@kerneltest003.31.prn1 ~]# for i in 1 4 8; do echo -n "$i cpus: "; \
./map_perf_test 32 $i | awk '{r += $3}END{print r " updates"}'; done
1 cpus: 2896553 updates
4 cpus: 9766395 updates
8 cpus: 17460553 updates
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
A BPF program is required to check the return register of a
map_elem_lookup() call before accessing memory. The verifier keeps
track of this by converting the type of the result register from
PTR_TO_MAP_VALUE_OR_NULL to PTR_TO_MAP_VALUE after a conditional
jump ensures safety. This check is currently exclusively performed
for the result register 0.
In the event the compiler reorders instructions, BPF_MOV64_REG
instructions may be moved before the conditional jump which causes
them to keep their type PTR_TO_MAP_VALUE_OR_NULL to which the
verifier objects when the register is accessed:
0: (b7) r1 = 10
1: (7b) *(u64 *)(r10 -8) = r1
2: (bf) r2 = r10
3: (07) r2 += -8
4: (18) r1 = 0x59c00000
6: (85) call 1
7: (bf) r4 = r0
8: (15) if r0 == 0x0 goto pc+1
R0=map_value(ks=8,vs=8) R4=map_value_or_null(ks=8,vs=8) R10=fp
9: (7a) *(u64 *)(r4 +0) = 0
R4 invalid mem access 'map_value_or_null'
This commit extends the verifier to keep track of all identical
PTR_TO_MAP_VALUE_OR_NULL registers after a map_elem_lookup() by
assigning them an ID and then marking them all when the conditional
jump is observed.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a start of a test suite for kernel selftests. This moves test_verifier
and test_maps over to tools/testing/selftests/bpf/ along with various
code improvements and also adds a script for invoking test_bpf module.
The test suite can simply be run via selftest framework, f.e.:
# cd tools/testing/selftests/bpf/
# make
# make run_tests
Both test_verifier and test_maps were kind of misplaced in samples/bpf/
directory and we were looking into adding them to selftests for a while
now, so it can be picked up by kbuild bot et al and hopefully also get
more exposure and thus new test case additions.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Daniel Borkmann
Martin KaFai Lau
Thomas Graf