LXR linux/tools/testing/selftests/bpf/progs/linked

   1// SPDX-License-Identifier: GPL-2.0
   2/* Copyright (c) 2021 Facebook */
   3
   4#include "vmlinux.h"
   5#include <bpf/bpf_helpers.h>
   6#include <bpf/bpf_tracing.h>
   7
   8/* weak and shared between two files */
   9const volatile int my_tid __weak;
  10long syscall_id __weak;
  11
  12int output_val1;
  13int output_ctx1;
  14int output_weak1;
  15
  16/* same "subprog" name in all files, but it's ok because they all are static */
  17static __noinline int subprog(int x)
  18{
  19        /* but different formula */
  20        return x * 1;
  21}
  22
  23/* Global functions can't be void */
  24int set_output_val1(int x)
  25{
  26        output_val1 = x + subprog(x);
  27        return x;
  28}
  29
  30/* This function can't be verified as global, as it assumes raw_tp/sys_enter
  31 * context and accesses syscall id (second argument). So we mark it as
  32 * __hidden, so that libbpf will mark it as static in the final object file,
  33 * right before verifying it in the kernel.
  34 *
  35 * But we don't mark it as __hidden here, rather at extern site. __hidden is
  36 * "contaminating" visibility, so it will get propagated from either extern or
  37 * actual definition (including from the losing __weak definition).
  38 */
  39void set_output_ctx1(__u64 *ctx)
  40{
  41        output_ctx1 = ctx[1]; /* long id, same as in BPF_PROG below */
  42}
  43
  44/* this weak instance should win because it's the first one */
  45__weak int set_output_weak(int x)
  46{
  47        output_weak1 = x;
  48        return x;
  49}
  50
  51extern int set_output_val2(int x);
  52
  53/* here we'll force set_output_ctx2() to be __hidden in the final obj file */
  54__hidden extern void set_output_ctx2(__u64 *ctx);
  55
  56SEC("raw_tp/sys_enter")
  57int BPF_PROG(handler1, struct pt_regs *regs, long id)
  58{
  59        if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id)
  60                return 0;
  61
  62        set_output_val2(1000);
  63        set_output_ctx2(ctx); /* ctx definition is hidden in BPF_PROG macro */
  64
  65        /* keep input value the same across both files to avoid dependency on
  66         * handler call order; differentiate by output_weak1 vs output_weak2.
  67         */
  68        set_output_weak(42);
  69
  70        return 0;
  71}
  72
  73char LICENSE[] SEC("license") = "GPL";
  74