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bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG

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Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.

After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).

This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].

 [1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
 [2] https://reviews.llvm.org/D111588
 [3] https://reviews.llvm.org/D111199

Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com
This commit is contained in:
Yonghong Song
2021-10-12 09:48:38 -07:00
committed by Andrii Nakryiko
parent ebf17ac628
commit 0f3ba10651
7 changed files with 46 additions and 46 deletions
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24
src/libbpf.c
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@@ -195,8 +195,8 @@ enum kern_feature_id {
FEAT_BTF_FLOAT,
/* BPF perf link support */
FEAT_PERF_LINK,
/* BTF_KIND_TAG support */
FEAT_BTF_TAG,
/* BTF_KIND_DECL_TAG support */
FEAT_BTF_DECL_TAG,
__FEAT_CNT,
};
@@ -2024,7 +2024,7 @@ 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";
case BTF_KIND_DECL_TAG: return "decl_tag";
default: return "unknown";
}
}
@@ -2524,9 +2524,9 @@ 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);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
return !has_func || !has_datasec || !has_func_global || !has_float || !has_tag;
return !has_func || !has_datasec || !has_func_global || !has_float || !has_decl_tag;
}
static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@@ -2535,15 +2535,15 @@ 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);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_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)) || (!has_tag && btf_is_tag(t))) {
/* replace VAR/TAG with INT */
if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
/* replace VAR/DECL_TAG with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
/*
* using size = 1 is the safest choice, 4 will be too
@@ -4248,7 +4248,7 @@ static int probe_kern_btf_float(void)
strs, sizeof(strs)));
}
static int probe_kern_btf_tag(void)
static int probe_kern_btf_decl_tag(void)
{
static const char strs[] = "\0tag";
__u32 types[] = {
@@ -4258,7 +4258,7 @@ static int probe_kern_btf_tag(void)
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
BTF_VAR_STATIC,
/* attr */
BTF_TYPE_TAG_ENC(1, 2, -1),
BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
@@ -4481,8 +4481,8 @@ 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,
[FEAT_BTF_DECL_TAG] = {
"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
},
};