1// SPDX-License-Identifier: GPL-2.0 2 3#include "vmlinux.h" 4#include <bpf/bpf_helpers.h> 5#include "bpf_misc.h" 6 7char _license[] SEC("license") = "GPL"; 8 9struct { 10 __uint(type, BPF_MAP_TYPE_HASH); 11 __uint(max_entries, 1); 12 __type(key, u64); 13 __type(value, u64); 14} m_hash SEC(".maps"); 15 16SEC("?raw_tp") 17__failure __msg("R8 invalid mem access 'map_value_or_null") 18int jeq_infer_not_null_ptr_to_btfid(void *ctx) 19{ 20 struct bpf_map *map = (struct bpf_map *)&m_hash; 21 struct bpf_map *inner_map = map->inner_map_meta; 22 u64 key = 0, ret = 0, *val; 23 24 val = bpf_map_lookup_elem(map, &key); 25 /* Do not mark ptr as non-null if one of them is 26 * PTR_TO_BTF_ID (R9), reject because of invalid 27 * access to map value (R8). 28 * 29 * Here, we need to inline those insns to access 30 * R8 directly, since compiler may use other reg 31 * once it figures out val==inner_map. 32 */ 33 asm volatile("r8 = %[val];\n" 34 "r9 = %[inner_map];\n" 35 "if r8 != r9 goto +1;\n" 36 "%[ret] = *(u64 *)(r8 +0);\n" 37 : [ret] "+r"(ret) 38 : [inner_map] "r"(inner_map), [val] "r"(val) 39 : "r8", "r9"); 40 41 return ret; 42} 43