On Mon, Dec 4, 2023 at 2:14 PM Andrii Nakryiko andrii.nakryiko@gmail.com wrote:
On Mon, Dec 4, 2023 at 12:14 PM Kyle Huey me@kylehuey.com wrote:
The test sets a hardware breakpoint and uses a bpf program to suppress the I/O availability signal if the ip matches the expected value.
Signed-off-by: Kyle Huey khuey@kylehuey.com
.../selftests/bpf/prog_tests/perf_skip.c | 95 +++++++++++++++++++ .../selftests/bpf/progs/test_perf_skip.c | 23 +++++ 2 files changed, 118 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_skip.c create mode 100644 tools/testing/selftests/bpf/progs/test_perf_skip.c
diff --git a/tools/testing/selftests/bpf/prog_tests/perf_skip.c b/tools/testing/selftests/bpf/prog_tests/perf_skip.c new file mode 100644 index 000000000000..b269a31669b7 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/perf_skip.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <test_progs.h> +#include "test_perf_skip.skel.h" +#include <linux/hw_breakpoint.h> +#include <sys/mman.h>
+#define BPF_OBJECT "test_perf_skip.bpf.o"
leftover?
Indeed. Fixed.
+static void handle_sig(int) +{
ASSERT_OK(1, "perf event not skipped");+}
+static noinline int test_function(void) +{
please add
asm volatile ("");
here to prevent compiler from actually inlining at the call site
Ok.
return 0;+}
+void serial_test_perf_skip(void) +{
sighandler_t previous;int duration = 0;struct test_perf_skip *skel = NULL;int map_fd = -1;long page_size = sysconf(_SC_PAGE_SIZE);uintptr_t *ip = NULL;int prog_fd = -1;struct perf_event_attr attr = {0};int perf_fd = -1;struct f_owner_ex owner;int err;previous = signal(SIGIO, handle_sig);skel = test_perf_skip__open_and_load();if (!ASSERT_OK_PTR(skel, "skel_load"))goto cleanup;prog_fd = bpf_program__fd(skel->progs.handler);if (!ASSERT_OK(prog_fd < 0, "bpf_program__fd"))goto cleanup;map_fd = bpf_map__fd(skel->maps.ip);if (!ASSERT_OK(map_fd < 0, "bpf_map__fd"))goto cleanup;ip = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);if (!ASSERT_OK_PTR(ip, "mmap bpf map"))goto cleanup;*ip = (uintptr_t)test_function;attr.type = PERF_TYPE_BREAKPOINT;attr.size = sizeof(attr);attr.bp_type = HW_BREAKPOINT_X;attr.bp_addr = (uintptr_t)test_function;attr.bp_len = sizeof(long);attr.sample_period = 1;attr.sample_type = PERF_SAMPLE_IP;attr.pinned = 1;attr.exclude_kernel = 1;attr.exclude_hv = 1;attr.precise_ip = 3;perf_fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);if (CHECK(perf_fd < 0, "perf_event_open", "err %d\n", perf_fd))please don't use CHECK() macro, stick to ASSERT_xxx()
Done.
also, we are going to run all this on different hardware and VMs, see how we skip tests if hardware support is not there. See test__skip usage in prog_tests/perf_branches.c, as one example
Hmm I suppose it should be conditioned on CONFIG_HAVE_HW_BREAKPOINT.
goto cleanup;err = fcntl(perf_fd, F_SETFL, O_ASYNC);I assume this is what will send SIGIO, right? Can you add a small comment explicitly saying this?
Done.
if (!ASSERT_OK(err, "fcntl(F_SETFL, O_ASYNC)"))goto cleanup;owner.type = F_OWNER_TID;owner.pid = gettid();err = fcntl(perf_fd, F_SETOWN_EX, &owner);if (!ASSERT_OK(err, "fcntl(F_SETOWN_EX)"))goto cleanup;err = ioctl(perf_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);if (!ASSERT_OK(err, "ioctl(PERF_EVENT_IOC_SET_BPF)"))goto cleanup;we have a better way to do this, please use bpf_program__attach_perf_event() instead
Done.
test_function();+cleanup:
if (perf_fd >= 0)close(perf_fd);if (ip)munmap(ip, page_size);if (skel)test_perf_skip__destroy(skel);signal(SIGIO, previous);+} diff --git a/tools/testing/selftests/bpf/progs/test_perf_skip.c b/tools/testing/selftests/bpf/progs/test_perf_skip.c new file mode 100644 index 000000000000..ef01a9161afe --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_perf_skip.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h>
+struct {
__uint(type, BPF_MAP_TYPE_ARRAY);__uint(max_entries, 1);__uint(map_flags, BPF_F_MMAPABLE);__type(key, uint32_t);__type(value, uintptr_t);+} ip SEC(".maps");
please use global variable:
__u64 ip;
and then access it from user-space side through skeleton
skel->bss.ip = &test_function;
Done.
+SEC("perf_event") +int handler(struct bpf_perf_event_data *data) +{
const uint32_t index = 0;uintptr_t *v = bpf_map_lookup_elem(&ip, &index);return !(v && *v == PT_REGS_IP(&data->regs));and so we the above global var suggestion this will be just:
return ip == PT_REGS_IP(&data->regs);
+}
+char _license[] SEC("license") = "GPL";
2.34.1
- Kyle