1 files changed, 55 insertions, 0 deletions

diff --git a/tools/perf/examples/bpf/augmented_syscalls.c b/tools/perf/examples/bpf/augmented_syscalls.c
new file mode 100644
index 000000000000..69a31386d8cd
--- /dev/null
+++ b/tools/perf/examples/bpf/augmented_syscalls.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Augment the openat syscall with the contents of the filename pointer argument.
+ *
+ * Test it with:
+ *
+ * perf trace -e tools/perf/examples/bpf/augmented_syscalls.c cat /etc/passwd > /dev/null
+ *
+ * It'll catch some openat syscalls related to the dynamic linked and
+ * the last one should be the one for '/etc/passwd'.
+ *
+ * This matches what is marshalled into the raw_syscall:sys_enter payload
+ * expected by the 'perf trace' beautifiers, and can be used by them unmodified,
+ * which will be done as that feature is implemented in the next csets, for now
+ * it will appear in a dump done by the default tracepoint handler in 'perf trace',
+ * that uses bpf_output__fprintf() to just dump those contents, as done with
+ * the bpf-output event associated with the __bpf_output__ map declared in
+ * tools/perf/include/bpf/stdio.h.
+ */
+
+#include <stdio.h>
+
+struct bpf_map SEC("maps") __augmented_syscalls__ = {
+       .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+       .key_size = sizeof(int),
+       .value_size = sizeof(u32),
+       .max_entries = __NR_CPUS__,
+};
+
+struct syscall_enter_openat_args {
+        unsigned long long common_tp_fields;
+        long               syscall_nr;
+        long               dfd;
+        char               *filename_ptr;
+        long               flags;
+        long               mode;
+};
+
+struct augmented_enter_openat_args {
+        struct syscall_enter_openat_args args;
+        char                             filename[64];
+};
+
+int syscall_enter(openat)(struct syscall_enter_openat_args *args)
+{
+        struct augmented_enter_openat_args augmented_args;
+
+        probe_read(&augmented_args.args, sizeof(augmented_args.args), args);
+        probe_read_str(&augmented_args.filename, sizeof(augmented_args.filename), args->filename_ptr);
+        perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU,
+                          &augmented_args, sizeof(augmented_args));
+        return 1;
+}
+
+license(GPL);