tools/testing/selftests/bpf/progs/test_subprogs.c

   1 #include "vmlinux.h"
   2 #include <bpf/bpf_helpers.h>
   3 #include <bpf/bpf_core_read.h>
   4
   5 const char LICENSE[] SEC("license") = "GPL";
   6
   7 __noinline int sub1(int x)
   8 {
   9         return x + 1;
  10 }
  11
  12 static __noinline int sub5(int v);
  13
  14 __noinline int sub2(int y)
  15 {
  16         return sub5(y + 2);
  17 }
  18
  19 static __noinline int sub3(int z)
  20 {
  21         return z + 3 + sub1(4);
  22 }
  23
  24 static __noinline int sub4(int w)
  25 {
  26         return w + sub3(5) + sub1(6);
  27 }
  28
  29 /* sub5() is an identitify function, just to test weirder functions layout and
  30  * call patterns
  31  */
  32 static __noinline int sub5(int v)
  33 {
  34         return sub1(v) - 1; /* compensates sub1()'s + 1 */
  35 }
  36
  37 /* unfortunately verifier rejects `struct task_struct *t` as an unkown pointer
  38  * type, so we need to accept pointer as integer and then cast it inside the
  39  * function
  40  */
  41 __noinline int get_task_tgid(uintptr_t t)
  42 {
  43         /* this ensures that CO-RE relocs work in multi-subprogs .text */
  44         return BPF_CORE_READ((struct task_struct *)(void *)t, tgid);
  45 }
  46
  47 int res1 = 0;
  48 int res2 = 0;
  49 int res3 = 0;
  50 int res4 = 0;
  51
  52 SEC("raw_tp/sys_enter")
  53 int prog1(void *ctx)
  54 {
  55         /* perform some CO-RE relocations to ensure they work with multi-prog
  56          * sections correctly
  57          */
  58         struct task_struct *t = (void *)bpf_get_current_task();
  59
  60         if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
  61                 return 1;
  62
  63         res1 = sub1(1) + sub3(2); /* (1 + 1) + (2 + 3 + (4 + 1)) = 12 */
  64         return 0;
  65 }
  66
  67 SEC("raw_tp/sys_exit")
  68 int prog2(void *ctx)
  69 {
  70         struct task_struct *t = (void *)bpf_get_current_task();
  71
  72         if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
  73                 return 1;
  74
  75         res2 = sub2(3) + sub3(4); /* (3 + 2) + (4 + 3 + (4 + 1)) = 17 */
  76         return 0;
  77 }
  78
  79 /* prog3 has the same section name as prog1 */
  80 SEC("raw_tp/sys_enter")
  81 int prog3(void *ctx)
  82 {
  83         struct task_struct *t = (void *)bpf_get_current_task();
  84
  85         if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
  86                 return 1;
  87
  88         res3 = sub3(5) + 6; /* (5 + 3 + (4 + 1)) + 6 = 19 */
  89         return 0;
  90 }
  91
  92 /* prog4 has the same section name as prog2 */
  93 SEC("raw_tp/sys_exit")
  94 int prog4(void *ctx)
  95 {
  96         struct task_struct *t = (void *)bpf_get_current_task();
  97
  98         if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
  99                 return 1;
 100
 101         res4 = sub4(7) + sub1(8); /* (7 + (5 + 3 + (4 + 1)) + (6 + 1)) + (8 + 1) = 36 */
 102         return 0;
 103 }