tools/perf/tests/bpf-script-test-prologue.c

   1 /*
   2  * bpf-script-test-prologue.c
   3  * Test BPF prologue
   4  */
   5 #ifndef LINUX_VERSION_CODE
   6 # error Need LINUX_VERSION_CODE
   7 # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
   8 #endif
   9 #define SEC(NAME) __attribute__((section(NAME), used))
  10
  11 #include <uapi/linux/fs.h>
  12
  13 /*
  14  * If CONFIG_PROFILE_ALL_BRANCHES is selected,
  15  * 'if' is redefined after include kernel header.
  16  * Recover 'if' for BPF object code.
  17  */
  18 #ifdef if
  19 # undef if
  20 #endif
  21
  22 #define FMODE_READ              0x1
  23 #define FMODE_WRITE             0x2
  24
  25 static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
  26         (void *) 6;
  27
  28 SEC("func=null_lseek file->f_mode offset orig")
  29 int bpf_func__null_lseek(void *ctx, int err, unsigned long _f_mode,
  30                          unsigned long offset, unsigned long orig)
  31 {
  32         fmode_t f_mode = (fmode_t)_f_mode;
  33
  34         if (err)
  35                 return 0;
  36         if (f_mode & FMODE_WRITE)
  37                 return 0;
  38         if (offset & 1)
  39                 return 0;
  40         if (orig == SEEK_CUR)
  41                 return 0;
  42         return 1;
  43 }
  44
  45 char _license[] SEC("license") = "GPL";
  46 int _version SEC("version") = LINUX_VERSION_CODE;