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: 3059303f59 ("samples/bpf: update tracex[23] examples to use per-cpu maps")
Fixes: 86af8b4191 ("Add sample for adding simple drop program to link")
Fixes: df570f5772 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_ARRAY")
Fixes: e155967179 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_HASH")
Fixes: ebb676daa1 ("bpf: Print function name in addition to function id")
Fixes: 5db58faf98 ("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>
eBPF programs attached to kprobes need to filter based on
current->pid, uid and other fields, so introduce helper functions:
u64 bpf_get_current_pid_tgid(void)
Return: current->tgid << 32 | current->pid
u64 bpf_get_current_uid_gid(void)
Return: current_gid << 32 | current_uid
bpf_get_current_comm(char *buf, int size_of_buf)
stores current->comm into buf
They can be used from the programs attached to TC as well to classify packets
based on current task fields.
Update tracex2 example to print histogram of write syscalls for each process
instead of aggregated for all.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
this example has two probes in one C file that attach to
different kprove events and use two different maps.
1st probe is x64 specific equivalent of dropmon. It attaches to
kfree_skb, retrevies 'ip' address of kfree_skb() caller and
counts number of packet drops at that 'ip' address. User space
prints 'location - count' map every second.
2nd probe attaches to kprobe:sys_write and computes a histogram
of different write sizes
Usage:
$ sudo tracex2
location 0xffffffff81695995 count 1
location 0xffffffff816d0da9 count 2
location 0xffffffff81695995 count 2
location 0xffffffff816d0da9 count 2
location 0xffffffff81695995 count 3
location 0xffffffff816d0da9 count 2
557145+0 records in
557145+0 records out
285258240 bytes (285 MB) copied, 1.02379 s, 279 MB/s
syscall write() stats
byte_size : count distribution
1 -> 1 : 3 | |
2 -> 3 : 0 | |
4 -> 7 : 0 | |
8 -> 15 : 0 | |
16 -> 31 : 2 | |
32 -> 63 : 3 | |
64 -> 127 : 1 | |
128 -> 255 : 1 | |
256 -> 511 : 0 | |
512 -> 1023 : 1118968 |************************************* |
Ctrl-C at any time. Kernel will auto cleanup maps and programs
$ addr2line -ape ./bld_x64/vmlinux 0xffffffff81695995
0xffffffff816d0da9 0xffffffff81695995:
./bld_x64/../net/ipv4/icmp.c:1038 0xffffffff816d0da9:
./bld_x64/../net/unix/af_unix.c:1231
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1427312966-8434-8-git-send-email-ast@plumgrid.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Daniel Borkmann
Alexei Starovoitov
Alexei Starovoitov