test_core_reloc_module.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2020 Facebook */
  3
  4#include "vmlinux.h"
  5#include <bpf/bpf_helpers.h>
  6#include <bpf/bpf_core_read.h>
  7#include <bpf/bpf_tracing.h>
  8
  9char _license[] SEC("license") = "GPL";
 10
 11struct bpf_testmod_test_read_ctx {
 12	/* field order is mixed up */
 13	size_t len;
 14	char *buf;
 15	loff_t off;
 16} __attribute__((preserve_access_index));
 17
 18struct {
 19	char in[256];
 20	char out[256];
 21	bool skip;
 22	uint64_t my_pid_tgid;
 23} data = {};
 24
 25struct core_reloc_module_output {
 26	long long len;
 27	long long off;
 28	int read_ctx_sz;
 29	bool read_ctx_exists;
 30	bool buf_exists;
 31	bool len_exists;
 32	bool off_exists;
 33	/* we have test_progs[-flavor], so cut flavor part */
 34	char comm[sizeof("test_progs")];
 35	int comm_len;
 36};
 37
 38SEC("raw_tp/bpf_testmod_test_read")
 39int BPF_PROG(test_core_module_probed,
 40	     struct task_struct *task,
 41	     struct bpf_testmod_test_read_ctx *read_ctx)
 42{
 43#if __has_builtin(__builtin_preserve_enum_value)
 44	struct core_reloc_module_output *out = (void *)&data.out;
 45	__u64 pid_tgid = bpf_get_current_pid_tgid();
 46	__s32 real_tgid = (__s32)(pid_tgid >> 32);
 47	__s32 real_pid = (__s32)pid_tgid;
 48
 49	if (data.my_pid_tgid != pid_tgid)
 50		return 0;
 51
 52	if (BPF_CORE_READ(task, pid) != real_pid || BPF_CORE_READ(task, tgid) != real_tgid)
 53		return 0;
 54
 55	out->len = BPF_CORE_READ(read_ctx, len);
 56	out->off = BPF_CORE_READ(read_ctx, off);
 57
 58	out->read_ctx_sz = bpf_core_type_size(struct bpf_testmod_test_read_ctx);
 59	out->read_ctx_exists = bpf_core_type_exists(struct bpf_testmod_test_read_ctx);
 60	out->buf_exists = bpf_core_field_exists(read_ctx->buf);
 61	out->off_exists = bpf_core_field_exists(read_ctx->off);
 62	out->len_exists = bpf_core_field_exists(read_ctx->len);
 63
 64	out->comm_len = BPF_CORE_READ_STR_INTO(&out->comm, task, comm);
 65#else
 66	data.skip = true;
 67#endif
 68
 69	return 0;
 70}
 71
 72SEC("tp_btf/bpf_testmod_test_read")
 73int BPF_PROG(test_core_module_direct,
 74	     struct task_struct *task,
 75	     struct bpf_testmod_test_read_ctx *read_ctx)
 76{
 77#if __has_builtin(__builtin_preserve_enum_value)
 78	struct core_reloc_module_output *out = (void *)&data.out;
 79	__u64 pid_tgid = bpf_get_current_pid_tgid();
 80	__s32 real_tgid = (__s32)(pid_tgid >> 32);
 81	__s32 real_pid = (__s32)pid_tgid;
 82
 83	if (data.my_pid_tgid != pid_tgid)
 84		return 0;
 85
 86	if (task->pid != real_pid || task->tgid != real_tgid)
 87		return 0;
 88
 89	out->len = read_ctx->len;
 90	out->off = read_ctx->off;
 91
 92	out->read_ctx_sz = bpf_core_type_size(struct bpf_testmod_test_read_ctx);
 93	out->read_ctx_exists = bpf_core_type_exists(struct bpf_testmod_test_read_ctx);
 94	out->buf_exists = bpf_core_field_exists(read_ctx->buf);
 95	out->off_exists = bpf_core_field_exists(read_ctx->off);
 96	out->len_exists = bpf_core_field_exists(read_ctx->len);
 97
 98	out->comm_len = BPF_CORE_READ_STR_INTO(&out->comm, task, comm);
 99#else
100	data.skip = true;
101#endif
102
103	return 0;
104}