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Message-Id: <20181122033611.15890-16-acme@kernel.org>
Date: Thu, 22 Nov 2018 00:35:58 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: Clark Williams <williams@...hat.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
David Ahern <dsahern@...il.com>,
Edward Cree <ecree@...arflare.com>,
Jiri Olsa <jolsa@...nel.org>, Martin KaFai Lau <kafai@...com>,
Namhyung Kim <namhyung@...nel.org>,
Wang Nan <wangnan0@...wei.com>, Yonghong Song <yhs@...com>
Subject: [PATCH 15/28] perf bpf: Reduce the hardcoded .max_entries for pid_maps
From: Arnaldo Carvalho de Melo <acme@...hat.com>
While working on augmented syscalls I got into this error:
# trace -vv --filter-pids 2469,1663 -e tools/perf/examples/bpf/augmented_raw_syscalls.c sleep 1
<SNIP>
libbpf: map 0 is "__augmented_syscalls__"
libbpf: map 1 is "__bpf_stdout__"
libbpf: map 2 is "pids_filtered"
libbpf: map 3 is "syscalls"
libbpf: collecting relocating info for: '.text'
libbpf: relo for 13 value 84 name 133
libbpf: relocation: insn_idx=3
libbpf: relocation: find map 3 (pids_filtered) for insn 3
libbpf: collecting relocating info for: 'raw_syscalls:sys_enter'
libbpf: relo for 8 value 0 name 0
libbpf: relocation: insn_idx=1
libbpf: relo for 8 value 0 name 0
libbpf: relocation: insn_idx=3
libbpf: relo for 9 value 28 name 178
libbpf: relocation: insn_idx=36
libbpf: relocation: find map 1 (__augmented_syscalls__) for insn 36
libbpf: collecting relocating info for: 'raw_syscalls:sys_exit'
libbpf: relo for 8 value 0 name 0
libbpf: relocation: insn_idx=0
libbpf: relo for 8 value 0 name 0
libbpf: relocation: insn_idx=2
bpf: config program 'raw_syscalls:sys_enter'
bpf: config program 'raw_syscalls:sys_exit'
libbpf: create map __bpf_stdout__: fd=3
libbpf: create map __augmented_syscalls__: fd=4
libbpf: create map syscalls: fd=5
libbpf: create map pids_filtered: fd=6
libbpf: added 13 insn from .text to prog raw_syscalls:sys_enter
libbpf: added 13 insn from .text to prog raw_syscalls:sys_exit
libbpf: load bpf program failed: Operation not permitted
libbpf: failed to load program 'raw_syscalls:sys_exit'
libbpf: failed to load object 'tools/perf/examples/bpf/augmented_raw_syscalls.c'
bpf: load objects failed: err=-4009: (Incorrect kernel version)
event syntax error: 'tools/perf/examples/bpf/augmented_raw_syscalls.c'
\___ Failed to load program for unknown reason
(add -v to see detail)
Run 'perf list' for a list of valid events
Usage: perf trace [<options>] [<command>]
or: perf trace [<options>] -- <command> [<options>]
or: perf trace record [<options>] [<command>]
or: perf trace record [<options>] -- <command> [<options>]
-e, --event <event> event/syscall selector. use 'perf list' to list available events
If I then try to use strace (perf trace'ing 'perf trace' needs some more work
before its possible) to get a bit more info I get:
# strace -e bpf trace --filter-pids 2469,1663 -e tools/perf/examples/bpf/augmented_raw_syscalls.c sleep 1
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_PERF_EVENT_ARRAY, key_size=4, value_size=4, max_entries=4, map_flags=0, inner_map_fd=0, map_name="__bpf_stdout__", map_ifindex=0}, 72) = 3
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_PERF_EVENT_ARRAY, key_size=4, value_size=4, max_entries=4, map_flags=0, inner_map_fd=0, map_name="__augmented_sys", map_ifindex=0}, 72) = 4
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4, value_size=1, max_entries=500, map_flags=0, inner_map_fd=0, map_name="syscalls", map_ifindex=0}, 72) = 5
bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_HASH, key_size=4, value_size=1, max_entries=512, map_flags=0, inner_map_fd=0, map_name="pids_filtered", map_ifindex=0}, 72) = 6
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_TRACEPOINT, insn_cnt=57, insns=0x1223f50, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(4, 18, 10), prog_flags=0, prog_name="sys_enter", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS}, 72) = 7
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_TRACEPOINT, insn_cnt=18, insns=0x1224120, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(4, 18, 10), prog_flags=0, prog_name="sys_exit", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS}, 72) = -1 EPERM (Operation not permitted)
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_TRACEPOINT, insn_cnt=18, insns=0x1224120, license="GPL", log_level=1, log_size=262144, log_buf="", kern_version=KERNEL_VERSION(4, 18, 10), prog_flags=0, prog_name="sys_exit", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS}, 72) = -1 EPERM (Operation not permitted)
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_KPROBE, insn_cnt=18, insns=0x1224120, license="GPL", log_level=0, log_size=0, log_buf=NULL, kern_version=KERNEL_VERSION(4, 18, 10), prog_flags=0, prog_name="sys_exit", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS}, 72) = -1 EPERM (Operation not permitted)
event syntax error: 'tools/perf/examples/bpf/augmented_raw_syscalls.c'
\___ Failed to load program for unknown reason
<SNIP similar output as without 'strace'>
#
I managed to create the maps, etc, but then installing the "sys_exit" hook into
the "raw_syscalls:sys_exit" tracepoint somehow gets -EPERMed...
I then go and try reducing the size of this new table:
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -47,6 +47,17 @@ struct augmented_filename {
#define SYS_OPEN 2
#define SYS_OPENAT 257
+struct syscall {
+ bool filtered;
+};
+
+struct bpf_map SEC("maps") syscalls = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(int),
+ .value_size = sizeof(struct syscall),
+ .max_entries = 500,
+};
And after reducing that .max_entries a tad, it works. So yeah, the "unknown
reason" should be related to the number of bytes all this is taking, reduce the
default for pid_map()s so that we can have a "syscalls" map with enough slots
for all syscalls in most arches. And take notes about this error message,
improve it :-)
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: David Ahern <dsahern@...il.com>
Cc: Edward Cree <ecree@...arflare.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Martin KaFai Lau <kafai@...com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>
Cc: Yonghong Song <yhs@...com>
Link: https://lkml.kernel.org/n/tip-yjzhak8asumz9e9hts2dgplp@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/perf/include/bpf/bpf.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/tools/perf/include/bpf/bpf.h b/tools/perf/include/bpf/bpf.h
index 04ecd425a237..bd5d7b4d7760 100644
--- a/tools/perf/include/bpf/bpf.h
+++ b/tools/perf/include/bpf/bpf.h
@@ -18,12 +18,20 @@ struct bpf_map {
unsigned int numa_node;
};
+/*
+ * FIXME: this should receive .max_entries as a parameter, as careful
+ * tuning of these limits is needed to avoid hitting limits that
+ * prevents other BPF constructs, such as tracepoint handlers,
+ * to get installed, with cryptic messages from libbpf, etc.
+ * For the current need, 'perf trace --filter-pids', 64 should
+ * be good enough, but this surely needs to be revisited.
+ */
#define pid_map(name, value_type) \
struct bpf_map SEC("maps") name = { \
.type = BPF_MAP_TYPE_HASH, \
.key_size = sizeof(pid_t), \
.value_size = sizeof(value_type), \
- .max_entries = 512, \
+ .max_entries = 64, \
}
static int (*bpf_map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags) = (void *)BPF_FUNC_map_update_elem;
--
2.14.5
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