On 12/4/23 3:14 PM, Kyle Huey 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@xxxxxxxxxxxx>
---
.../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"
+
+static void handle_sig(int)
I hit a warning here:
home/yhs/work/bpf-next/tools/testing/selftests/bpf/prog_tests/perf_skip.c:10:27: error: omitting the parameter name in a function definition is a C23 extension [-Werror,-Wc23-extensions]
10 | static void handle_sig(int)
|
Add a parameter and marked as unused can resolve the issue.
#define __always_unused __attribute__((__unused__))
static void handle_sig(int unused __always_unused)
{
ASSERT_OK(1, "perf event not skipped");
}
+{
+ ASSERT_OK(1, "perf event not skipped");
+}
+
+static noinline int test_function(void)
+{
+ 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))
+ goto cleanup;
+
+ err = fcntl(perf_fd, F_SETFL, O_ASYNC);
+ if (!ASSERT_OK(err, "fcntl(F_SETFL, O_ASYNC)"))
+ goto cleanup;
+
+ owner.type = F_OWNER_TID;
+ owner.pid = gettid();
I hit a compilation failure here:
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/prog_tests/perf_skip.c:75:14: error: call to undeclared function 'gettid'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
75 | owner.pid = gettid();
| ^
If you looked at some other examples, the common usage is do 'syscall(SYS_gettid)'.
So the following patch should fix the compilation error:
#include <sys/syscall.h>
...
owner.pid = syscall(SYS_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;
+
+ test_function();
As Andrii has mentioned in previous comments, we will have
issue is RELEASE version of selftest is built
RELEASE=1 make ...
See https://lore.kernel.org/bpf/20231127050342.1945270-1-yonghong.song@xxxxxxxxx
+
+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");
+
+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));
+}
+
+char _license[] SEC("license") = "GPL";
