Re: [PATCH bpf-next v7 20/22] selftests/bpf: Add __set_global() and __ret_global() test tags

[Yonghong Song <yonghong.song@linux.dev>]

On 9/28/26 5:52 PM, bot+bpf-ci@kernel.org wrote:
>> diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
>> index f3dbc3b59bff..9afa163fac5a 100644
>> --- a/tools/testing/selftests/bpf/progs/bpf_misc.h
>> +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
>> @@ -93,6 +93,11 @@
>>    * __failure         Expect program load failure in privileged mode.
>>    * __failure_unpriv  Expect program load failure in unprivileged mode.
>>    *
>> + * __set_global      Set a global variable of the program to a value before
>> + *                   executing it.
>> + * __ret_global      Execute the program and check that a global variable
>> + *                   holds the given value afterwards. The variable has to
>> + *                   live in .bss or .data and be four or eight bytes wide.
>>    * __retval          Execute the program using BPF_PROG_TEST_RUN command,
>>    *                   expect return value to match passed parameter:
>>    *                   - a decimal number
> [ ... ]
>
>> diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c
>> index 25eeb1c1248b..2492841f7a49 100644
>> --- a/tools/testing/selftests/bpf/test_loader.c
>> +++ b/tools/testing/selftests/bpf/test_loader.c
> [ ... ]
>
>> +static int find_global_var(struct bpf_object *obj, const char *name,
>> +			   struct bpf_map **map, __u32 *off, __u32 *sz,
>> +			   bool *is_signed)
>> +{
>> +	static const char * const secs[] = { ".bss", ".data" };
>> +	struct btf *btf = bpf_object__btf(obj);
>> +	int i, s;
>> +	__u32 vsz;
>> +
>> +	if (!btf) {
>> +		PRINT_FAIL("no BTF for object\n");
>> +		return -ENOENT;
>> +	}
>> +
>> +	for (s = 0; s < ARRAY_SIZE(secs); s++) {
>> +		const struct btf_type *sec, *vt;
>> +		const struct btf_var_secinfo *vsi;
>> +		struct bpf_map *m = NULL, *iter;
>> +		size_t slen = strlen(secs[s]);
>> +		int id;
>> +
>> +		bpf_object__for_each_map(iter, obj) {
>> +			const char *mname = bpf_map__name(iter);
>> +			size_t len = mname ? strlen(mname) : 0;
>> +
>> +			if (len >= slen && strcmp(mname + len - slen, secs[s]) == 0) {
>> +				m = iter;
>> +				break;
>> +			}
>> +		}
> This isn't a bug, but could the map loop here be replaced with
> bpf_object__find_map_by_name(obj, secs[s]), as veristat's
> set_global_vars() does? That would tie the map to the DATASEC by its
> section name and make the comment about the two lookups not agreeing on a
> size unnecessary.

Will do. Thanks!

>
>> +		id = btf__find_by_name_kind(btf, secs[s], BTF_KIND_DATASEC);
>> +		if (!m || id < 0)
>> +			continue;
>> +
>> +		sec = btf__type_by_id(btf, id);
>> +		vsi = btf_var_secinfos(sec);
>> +		for (i = 0; i < btf_vlen(sec); i++, vsi++) {
>> +			const struct btf_type *var = btf__type_by_id(btf, vsi->type);
>> +
>> +			if (strcmp(btf__name_by_offset(btf, var->name_off), name))
>> +				continue;
>> +			if (vsi->size != 4 && vsi->size != 8) {
>> +				PRINT_FAIL("'%s' is %u bytes, only 4 and 8 are supported\n",
>> +					   name, vsi->size);
>> +				return -EINVAL;
>> +			}
>> +			vt = btf__type_by_id(btf, btf__resolve_type(btf, var->type));
>> +			if (!vt || !(btf_is_int(vt) || btf_is_any_enum(vt))) {
>> +				PRINT_FAIL("'%s' is not an int or an enum\n", name);
>> +				return -EINVAL;
>> +			}
>> +			*is_signed = global_var_is_signed(vt);
>> +			/*
>> +			 * The map is found by the suffix of its name and the
>> +			 * section by its own, so nothing so far has made the
>> +			 * two agree on a size.
>> +			 */
>> +			vsz = bpf_map__value_size(m);
>> +			if (vsi->offset > vsz || vsi->size > vsz - vsi->offset) {
>> +				PRINT_FAIL("'%s' at %u+%u is outside '%s' of %u bytes\n",
>> +					   name, vsi->offset, vsi->size,
>> +					   bpf_map__name(m), vsz);
>> +				return -EINVAL;
>> +			}
>> +			*map = m;
>> +			*off = vsi->offset;
>> +			*sz = vsi->size;
>> +			return 0;
>> +		}
>> +	}
>> +
>> +	PRINT_FAIL("no global variable '%s'\n", name);
>> +	return -ENOENT;
>> +}
> [ ... ]
>
>
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
>
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/36502848904