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1// SPDX-License-Identifier: GPL-2.02/* Copyright (c) 2021 Facebook */3 4#include "vmlinux.h"5#include <bpf/bpf_helpers.h>6#include <bpf/bpf_tracing.h>7#include <bpf/bpf_core_read.h>8#include "bpf_misc.h"9 10/* weak and shared between both files */11const volatile int my_tid __weak;12long syscall_id __weak;13 14int output_val2;15int output_ctx2;16int output_weak2; /* should stay zero */17 18/* same "subprog" name in all files, but it's ok because they all are static */19static __noinline int subprog(int x)20{21 /* but different formula */22 return x * 2;23}24 25/* Global functions can't be void */26int set_output_val2(int x)27{28 output_val2 = 2 * x + 2 * subprog(x);29 return 2 * x;30}31 32/* This function can't be verified as global, as it assumes raw_tp/sys_enter33 * context and accesses syscall id (second argument). So we mark it as34 * __hidden, so that libbpf will mark it as static in the final object file,35 * right before verifying it in the kernel.36 *37 * But we don't mark it as __hidden here, rather at extern site. __hidden is38 * "contaminating" visibility, so it will get propagated from either extern or39 * actual definition (including from the losing __weak definition).40 */41void set_output_ctx2(__u64 *ctx)42{43 output_ctx2 = ctx[1]; /* long id, same as in BPF_PROG below */44}45 46/* this weak instance should lose, because it will be processed second */47__weak int set_output_weak(int x)48{49 static volatile int whatever;50 51 /* make sure we use CO-RE relocations in a weak function, this used to52 * cause problems for BPF static linker53 */54 whatever = 2 * bpf_core_type_size(struct task_struct);55 __sink(whatever);56 57 output_weak2 = x;58 return 2 * x;59}60 61extern int set_output_val1(int x);62 63/* here we'll force set_output_ctx1() to be __hidden in the final obj file */64__hidden extern void set_output_ctx1(__u64 *ctx);65 66SEC("?raw_tp/sys_enter")67int BPF_PROG(handler2, struct pt_regs *regs, long id)68{69 static volatile int whatever;70 71 if (my_tid != (s32)bpf_get_current_pid_tgid() || id != syscall_id)72 return 0;73 74 /* make sure we have CO-RE relocations in main program */75 whatever = bpf_core_type_size(struct task_struct);76 __sink(whatever);77 78 set_output_val1(2000);79 set_output_ctx1(ctx); /* ctx definition is hidden in BPF_PROG macro */80 81 /* keep input value the same across both files to avoid dependency on82 * handler call order; differentiate by output_weak1 vs output_weak2.83 */84 set_output_weak(42);85 86 return 0;87}88 89char LICENSE[] SEC("license") = "GPL";90