tools/perf/examples/bpf/hello.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/bpf.h>
   3 #include <bpf/bpf_helpers.h>
   4
   5 struct __bpf_stdout__ {
   6         __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
   7         __type(key, int);
   8         __type(value, __u32);
   9         __uint(max_entries, __NR_CPUS__);
  10 } __bpf_stdout__ SEC(".maps");
  11
  12 #define puts(from) \
  13         ({ const int __len = sizeof(from); \
  14            char __from[sizeof(from)] = from;                    \
  15            bpf_perf_event_output(args, &__bpf_stdout__, BPF_F_CURRENT_CPU, \
  16                           &__from, __len & (sizeof(from) - 1)); })
  17
  18 struct syscall_enter_args;
  19
  20 SEC("raw_syscalls:sys_enter")
  21 int sys_enter(struct syscall_enter_args *args)
  22 {
  23         puts("Hello, world\n");
  24         return 0;
  25 }
  26
  27 char _license[] SEC("license") = "GPL";