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libbpf: Add support for BTF_KIND_TAG

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Add BTF_KIND_TAG support for parsing and dedup.
Also added sanitization for BTF_KIND_TAG. If BTF_KIND_TAG is not
supported in the kernel, sanitize it to INTs.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210914223025.246687-1-yhs@fb.com
This commit is contained in:
Yonghong Song
2021-09-14 15:30:25 -07:00
committed by Alexei Starovoitov
parent 30025e8bd8
commit 5b84bd1036
6 changed files with 118 additions and 3 deletions
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31
tools/lib/bpf/libbpf.c
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@@ -195,6 +195,8 @@ enum kern_feature_id {
FEAT_BTF_FLOAT,
/* BPF perf link support */
FEAT_PERF_LINK,
/* BTF_KIND_TAG support */
FEAT_BTF_TAG,
__FEAT_CNT,
};
@@ -1986,6 +1988,7 @@ static const char *__btf_kind_str(__u16 kind)
case BTF_KIND_VAR: return "var";
case BTF_KIND_DATASEC: return "datasec";
case BTF_KIND_FLOAT: return "float";
case BTF_KIND_TAG: return "tag";
default: return "unknown";
}
}
@@ -2485,8 +2488,9 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_tag = kernel_supports(obj, FEAT_BTF_TAG);
return !has_func || !has_datasec || !has_func_global || !has_float;
return !has_func || !has_datasec || !has_func_global || !has_float || !has_tag;
}
static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@@ -2495,14 +2499,15 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_tag = kernel_supports(obj, FEAT_BTF_TAG);
struct btf_type *t;
int i, j, vlen;
for (i = 1; i <= btf__get_nr_types(btf); i++) {
t = (struct btf_type *)btf__type_by_id(btf, i);
if (!has_datasec && btf_is_var(t)) {
/* replace VAR with INT */
if ((!has_datasec && btf_is_var(t)) || (!has_tag && btf_is_tag(t))) {
/* replace VAR/TAG with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
/*
* using size = 1 is the safest choice, 4 will be too
@@ -4212,6 +4217,23 @@ static int probe_kern_btf_float(void)
strs, sizeof(strs)));
}
static int probe_kern_btf_tag(void)
{
static const char strs[] = "\0tag";
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* VAR x */ /* [2] */
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
BTF_VAR_STATIC,
/* attr */
BTF_TYPE_TAG_ENC(1, 2, -1),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_array_mmap(void)
{
struct bpf_create_map_attr attr = {
@@ -4428,6 +4450,9 @@ static struct kern_feature_desc {
[FEAT_PERF_LINK] = {
"BPF perf link support", probe_perf_link,
},
[FEAT_BTF_TAG] = {
"BTF_KIND_TAG support", probe_kern_btf_tag,
},
};
static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)