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// SPDX-License-Identifier: GPL-2.0
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
char _license[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, u64);
__type(value, u64);
} m_hash SEC(".maps");
SEC("?raw_tp")
__failure __msg("R8 invalid mem access 'map_value_or_null")
int jeq_infer_not_null_ptr_to_btfid(void *ctx)
{
struct bpf_map *map = (struct bpf_map *)&m_hash;
struct bpf_map *inner_map = map->inner_map_meta;
u64 key = 0, ret = 0, *val;
val = bpf_map_lookup_elem(map, &key);
/* Do not mark ptr as non-null if one of them is
* PTR_TO_BTF_ID (R9), reject because of invalid
* access to map value (R8).
*
* Here, we need to inline those insns to access
* R8 directly, since compiler may use other reg
* once it figures out val==inner_map.
*/
asm volatile("r8 = %[val];\n"
"r9 = %[inner_map];\n"
"if r8 != r9 goto +1;\n"
"%[ret] = *(u64 *)(r8 +0);\n"
: [ret] "+r"(ret)
: [inner_map] "r"(inner_map), [val] "r"(val)
: "r8", "r9");
return ret;
}
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