49 lines · c
1// SPDX-License-Identifier: GPL-2.02/* Copyright (C) 2023. Huawei Technologies Co., Ltd */3#include <linux/types.h>4#include <bpf/bpf_helpers.h>5 6#include "bpf_experimental.h"7#include "bpf_misc.h"8 9char _license[] SEC("license") = "GPL";10 11struct bin_data {12 char blob[32];13};14 15#define private(name) SEC(".bss." #name) __hidden __attribute__((aligned(8)))16private(kptr) struct bin_data __kptr * ptr;17 18SEC("tc")19__naked int kptr_xchg_inline(void)20{21 asm volatile (22 "r1 = %[ptr] ll;"23 "r2 = 0;"24 "call %[bpf_kptr_xchg];"25 "if r0 == 0 goto 1f;"26 "r1 = r0;"27 "r2 = 0;"28 "call %[bpf_obj_drop_impl];"29 "1:"30 "r0 = 0;"31 "exit;"32 :33 : __imm_addr(ptr),34 __imm(bpf_kptr_xchg),35 __imm(bpf_obj_drop_impl)36 : __clobber_all37 );38}39 40/* BTF FUNC records are not generated for kfuncs referenced41 * from inline assembly. These records are necessary for42 * libbpf to link the program. The function below is a hack43 * to ensure that BTF FUNC records are generated.44 */45void __btf_root(void)46{47 bpf_obj_drop(NULL);48}49