From e1cc1f39981b06ba22a0c92e800e9fd8ba59d2d3 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Mon, 14 Mar 2022 11:20:42 -0700 Subject: [PATCH] selftests/bpf: Test skipping stacktrace Add a test case for stacktrace with skip > 0 using a small sized buffer. It didn't support skipping entries greater than or equal to the size of buffer and filled the skipped part with 0. Signed-off-by: Namhyung Kim Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20220314182042.71025-2-namhyung@kernel.org --- .../selftests/bpf/prog_tests/stacktrace_map_skip.c | 63 ++++++++++++++++++++ .../selftests/bpf/progs/stacktrace_map_skip.c | 68 ++++++++++++++++++++++ 2 files changed, 131 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c create mode 100644 tools/testing/selftests/bpf/progs/stacktrace_map_skip.c diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c new file mode 100644 index 0000000..1932b1e --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include "stacktrace_map_skip.skel.h" + +#define TEST_STACK_DEPTH 2 + +void test_stacktrace_map_skip(void) +{ + struct stacktrace_map_skip *skel; + int stackid_hmap_fd, stackmap_fd, stack_amap_fd; + int err, stack_trace_len; + + skel = stacktrace_map_skip__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) + return; + + /* find map fds */ + stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap); + if (!ASSERT_GE(stackid_hmap_fd, 0, "stackid_hmap fd")) + goto out; + + stackmap_fd = bpf_map__fd(skel->maps.stackmap); + if (!ASSERT_GE(stackmap_fd, 0, "stackmap fd")) + goto out; + + stack_amap_fd = bpf_map__fd(skel->maps.stack_amap); + if (!ASSERT_GE(stack_amap_fd, 0, "stack_amap fd")) + goto out; + + skel->bss->pid = getpid(); + + err = stacktrace_map_skip__attach(skel); + if (!ASSERT_OK(err, "skel_attach")) + goto out; + + /* give some time for bpf program run */ + sleep(1); + + /* disable stack trace collection */ + skel->bss->control = 1; + + /* 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 (!ASSERT_OK(err, "compare_map_keys stackid_hmap vs. stackmap")) + goto out; + + err = compare_map_keys(stackmap_fd, stackid_hmap_fd); + if (!ASSERT_OK(err, "compare_map_keys stackmap vs. stackid_hmap")) + goto out; + + stack_trace_len = TEST_STACK_DEPTH * sizeof(__u64); + err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len); + if (!ASSERT_OK(err, "compare_stack_ips stackmap vs. stack_amap")) + goto out; + + if (!ASSERT_EQ(skel->bss->failed, 0, "skip_failed")) + goto out; + +out: + stacktrace_map_skip__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c b/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c new file mode 100644 index 0000000..2eb297d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/stacktrace_map_skip.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#define TEST_STACK_DEPTH 2 +#define TEST_MAX_ENTRIES 16384 + +typedef __u64 stack_trace_t[TEST_STACK_DEPTH]; + +struct { + __uint(type, BPF_MAP_TYPE_STACK_TRACE); + __uint(max_entries, TEST_MAX_ENTRIES); + __type(key, __u32); + __type(value, stack_trace_t); +} stackmap SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, TEST_MAX_ENTRIES); + __type(key, __u32); + __type(value, __u32); +} stackid_hmap SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, TEST_MAX_ENTRIES); + __type(key, __u32); + __type(value, stack_trace_t); +} stack_amap SEC(".maps"); + +int pid = 0; +int control = 0; +int failed = 0; + +SEC("tracepoint/sched/sched_switch") +int oncpu(struct trace_event_raw_sched_switch *ctx) +{ + __u32 max_len = TEST_STACK_DEPTH * sizeof(__u64); + __u32 key = 0, val = 0; + __u64 *stack_p; + + if (pid != (bpf_get_current_pid_tgid() >> 32)) + return 0; + + if (control) + return 0; + + /* it should allow skipping whole buffer size entries */ + key = bpf_get_stackid(ctx, &stackmap, TEST_STACK_DEPTH); + if ((int)key >= 0) { + /* The size of stackmap and stack_amap should be the same */ + bpf_map_update_elem(&stackid_hmap, &key, &val, 0); + stack_p = bpf_map_lookup_elem(&stack_amap, &key); + if (stack_p) { + bpf_get_stack(ctx, stack_p, max_len, TEST_STACK_DEPTH); + /* it wrongly skipped all the entries and filled zero */ + if (stack_p[0] == 0) + failed = 1; + } + } else { + /* old kernel doesn't support skipping that many entries */ + failed = 2; + } + + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.7.4