1// SPDX-License-Identifier: GPL-2.0 2 3#include "vmlinux.h" 4#include <bpf/bpf_helpers.h> 5#include "bpf_misc.h" 6 7#ifndef __clang__ 8#pragma GCC diagnostic ignored "-Warray-bounds" 9#endif 10 11char _license[] SEC("license") = "GPL"; 12 13struct { 14 __uint(type, BPF_MAP_TYPE_HASH); 15 __uint(max_entries, 1); 16 __type(key, u64); 17 __type(value, u64); 18} m_hash SEC(".maps"); 19 20SEC("?raw_tp") 21__failure __msg("R8 invalid mem access 'map_value_or_null") 22int jeq_infer_not_null_ptr_to_btfid(void *ctx) 23{ 24 struct bpf_map *map = (struct bpf_map *)&m_hash; 25 struct bpf_map *inner_map = map->inner_map_meta; 26 u64 key = 0, ret = 0, *val; 27 28 val = bpf_map_lookup_elem(map, &key); 29 /* Do not mark ptr as non-null if one of them is 30 * PTR_TO_BTF_ID (R9), reject because of invalid 31 * access to map value (R8). 32 * 33 * Here, we need to inline those insns to access 34 * R8 directly, since compiler may use other reg 35 * once it figures out val==inner_map. 36 */ 37 asm volatile("r8 = %[val];\n" 38 "r9 = %[inner_map];\n" 39 "if r8 != r9 goto +1;\n" 40 "%[ret] = *(u64 *)(r8 +0);\n" 41 : [ret] "+r"(ret) 42 : [inner_map] "r"(inner_map), [val] "r"(val) 43 : "r8", "r9"); 44 45 return ret; 46} 47