Commit 13790d1c authored by Song Liu's avatar Song Liu Committed by Daniel Borkmann

bpf: add selftest for stackmap with build_id in NMI context

This new test captures stackmap with build_id with hardware event
PERF_COUNT_HW_CPU_CYCLES.

Because we only support one ips-to-build_id lookup per cpu in NMI
context, stack_amap will not be able to do the lookup in this test.
Therefore, we didn't do compare_stack_ips(), as it will alwasy fail.

urandom_read.c is extended to run configurable cycles so that it can be
caught by the perf event.
Signed-off-by: 's avatarSong Liu <songliubraving@fb.com>
Signed-off-by: 's avatarDaniel Borkmann <daniel@iogearbox.net>
parent bae77c5e
......@@ -1272,6 +1272,139 @@ static void test_stacktrace_build_id(void)
return;
}
static void test_stacktrace_build_id_nmi(void)
{
int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
const char *file = "./test_stacktrace_build_id.o";
int err, pmu_fd, prog_fd;
struct perf_event_attr attr = {
.sample_freq = 5000,
.freq = 1,
.type = PERF_TYPE_HARDWARE,
.config = PERF_COUNT_HW_CPU_CYCLES,
};
__u32 key, previous_key, val, duration = 0;
struct bpf_object *obj;
char buf[256];
int i, j;
struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
int build_id_matches = 0;
err = bpf_prog_load(file, BPF_PROG_TYPE_PERF_EVENT, &obj, &prog_fd);
if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
return;
pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
0 /* cpu 0 */, -1 /* group id */,
0 /* flags */);
if (CHECK(pmu_fd < 0, "perf_event_open",
"err %d errno %d. Does the test host support PERF_COUNT_HW_CPU_CYCLES?\n",
pmu_fd, errno))
goto close_prog;
err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",
err, errno))
goto close_pmu;
err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",
err, errno))
goto disable_pmu;
/* find map fds */
control_map_fd = bpf_find_map(__func__, obj, "control_map");
if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
"err %d errno %d\n", err, errno))
goto disable_pmu;
stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",
err, errno))
goto disable_pmu;
stack_amap_fd = bpf_find_map(__func__, obj, "stack_amap");
if (CHECK(stack_amap_fd < 0, "bpf_find_map stack_amap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")
== 0);
assert(system("taskset 0x1 ./urandom_read 100000") == 0);
/* disable stack trace collection */
key = 0;
val = 1;
bpf_map_update_elem(control_map_fd, &key, &val, 0);
/* for every element in stackid_hmap, we can find a corresponding one
* in stackmap, and vise versa.
*/
err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
err = extract_build_id(buf, 256);
if (CHECK(err, "get build_id with readelf",
"err %d errno %d\n", err, errno))
goto disable_pmu;
err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
if (CHECK(err, "get_next_key from stackmap",
"err %d, errno %d\n", err, errno))
goto disable_pmu;
do {
char build_id[64];
err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
if (CHECK(err, "lookup_elem from stackmap",
"err %d, errno %d\n", err, errno))
goto disable_pmu;
for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
id_offs[i].offset != 0) {
for (j = 0; j < 20; ++j)
sprintf(build_id + 2 * j, "%02x",
id_offs[i].build_id[j] & 0xff);
if (strstr(buf, build_id) != NULL)
build_id_matches = 1;
}
previous_key = key;
} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
if (CHECK(build_id_matches < 1, "build id match",
"Didn't find expected build ID from the map\n"))
goto disable_pmu;
/*
* We intentionally skip compare_stack_ips(). This is because we
* only support one in_nmi() ips-to-build_id translation per cpu
* at any time, thus stack_amap here will always fallback to
* BPF_STACK_BUILD_ID_IP;
*/
disable_pmu:
ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
close_pmu:
close(pmu_fd);
close_prog:
bpf_object__close(obj);
}
#define MAX_CNT_RAWTP 10ull
#define MAX_STACK_RAWTP 100
struct get_stack_trace_t {
......@@ -1425,6 +1558,7 @@ int main(void)
test_tp_attach_query();
test_stacktrace_map();
test_stacktrace_build_id();
test_stacktrace_build_id_nmi();
test_stacktrace_map_raw_tp();
test_get_stack_raw_tp();
......
......@@ -6,15 +6,21 @@
#include <stdlib.h>
#define BUF_SIZE 256
int main(void)
int main(int argc, char *argv[])
{
int fd = open("/dev/urandom", O_RDONLY);
int i;
char buf[BUF_SIZE];
int count = 4;
if (fd < 0)
return 1;
for (i = 0; i < 4; ++i)
if (argc == 2)
count = atoi(argv[1]);
for (i = 0; i < count; ++i)
read(fd, buf, BUF_SIZE);
close(fd);
......
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