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Date: Tue, 1 May 2018 17:02:20 -0700
From: Song Liu <songliubraving@...com>
To: <netdev@...r.kernel.org>
CC: Song Liu <songliubraving@...com>, <kernel-team@...com>
Subject: [PATCH bpf-next 2/2] 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: Song Liu <songliubraving@...com>
---
tools/testing/selftests/bpf/test_progs.c | 137 +++++++++++++++++++++++++++++
tools/testing/selftests/bpf/urandom_read.c | 10 ++-
2 files changed, 145 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index aa336f0..00bb08c 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -1272,6 +1272,142 @@ 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))
+ goto out;
+
+ 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);
+
+out:
+ return;
+}
+
#define MAX_CNT_RAWTP 10ull
#define MAX_STACK_RAWTP 100
struct get_stack_trace_t {
@@ -1425,6 +1561,7 @@ 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();
diff --git a/tools/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c
index 4acfdeb..9de8b7c 100644
--- a/tools/testing/selftests/bpf/urandom_read.c
+++ b/tools/testing/selftests/bpf/urandom_read.c
@@ -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);
--
2.9.5
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