btf: add func_proto support
Two new btf kinds, BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO, have been added in kernel since https://patchwork.ozlabs.org/cover/1000176/ to support better func introspection. Currently, for a DW_TAG_subroutine_type dwarf type, a simple "void *" is generated instead of real subroutine type. This patch teaches pahole to generate BTF_KIND_FUNC_PROTO properly. After this patch, pahole should have complete type coverage for C frontend with types a bpf program cares. For example, $ cat t1.c typedef int __int32; struct t1 { int a1; int (*f1)(char p1, __int32 p2); } g1; $ cat t2.c typedef int __int32; struct t2 { int a2; int (*f2)(char q1, __int32 q2, ...); int (*f3)(); } g2; int main() { return 0; } $ gcc -O2 -o t1 -g t1.c t2.c $ pahole -JV t1 File t1: [1] TYPEDEF __int32 type_id=2 [2] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED [3] STRUCT t1 kind_flag=0 size=16 vlen=2 a1 type_id=2 bits_offset=0 f1 type_id=6 bits_offset=64 [4] FUNC_PROTO (anon) return=2 args=(5 (anon), 1 (anon)) [5] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none) [6] PTR (anon) type_id=4 [7] TYPEDEF __int32 type_id=8 [8] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED [9] STRUCT t2 kind_flag=0 size=24 vlen=3 a2 type_id=8 bits_offset=0 f2 type_id=12 bits_offset=64 f3 type_id=14 bits_offset=128 [10] FUNC_PROTO (anon) return=8 args=(11 (anon), 7 (anon), vararg) [11] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none) [12] PTR (anon) type_id=10 [13] FUNC_PROTO (anon) return=8 args=(vararg) [14] PTR (anon) type_id=13 $ In the above example, type [4], [10] and [13] represent the func_proto types. BTF_KIND_FUNC, which represents a real subprogram, is not generated in this patch and will be considered later. Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@fb.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Yonghong Song
Arnaldo Carvalho de Melo
parent
8630ce4042
commit
3aa3fd506e
15
btf.h
15
btf.h
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@ -67,8 +67,10 @@ struct btf_type {
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#define BTF_KIND_VOLATILE 9 /* Volatile */
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#define BTF_KIND_CONST 10 /* Const */
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#define BTF_KIND_RESTRICT 11 /* Restrict */
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#define BTF_KIND_MAX 11
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#define NR_BTF_KINDS 12
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#define BTF_KIND_FUNC 12 /* Function */
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#define BTF_KIND_FUNC_PROTO 13 /* Function Proto */
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#define BTF_KIND_MAX 13
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#define NR_BTF_KINDS 14
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/* For some specific BTF_KIND, "struct btf_type" is immediately
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* followed by extra data.
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@ -126,4 +128,13 @@ struct btf_member {
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#define BTF_MEMBER_BITFIELD_SIZE(val) ((val) >> 24)
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#define BTF_MEMBER_BIT_OFFSET(val) ((val) & 0xffffff)
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/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
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* The exact number of btf_param is stored in the vlen (of the
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* info in "struct btf_type").
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*/
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struct btf_param {
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__u32 name_off;
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__u32 type;
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};
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#endif /* _UAPI__LINUX_BTF_H__ */
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@ -170,10 +170,7 @@ static int tag__encode_btf(struct tag *tag, uint32_t core_id, struct btf *btf,
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case DW_TAG_enumeration_type:
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return enumeration_type__encode(btf, tag);
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case DW_TAG_subroutine_type:
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/* A dummy void * to avoid a shift in btf->type_index */
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btf_verbose_log("Filling unsupported DW_TAG_%s(0x%x) with void *\n",
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dwarf_tag_name(tag->tag), tag->tag);
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return btf__add_ref_type(btf, BTF_KIND_PTR, 0, 0, false);
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return btf__add_func_proto(btf, tag__ftype(tag), type_id_off);
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default:
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fprintf(stderr, "Unsupported DW_TAG_%s(0x%x)\n",
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dwarf_tag_name(tag->tag), tag->tag);
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125
libbtf.c
125
libbtf.c
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@ -142,6 +142,8 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
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[BTF_KIND_VOLATILE] = "VOLATILE",
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[BTF_KIND_CONST] = "CONST",
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[BTF_KIND_RESTRICT] = "RESTRICT",
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[BTF_KIND_FUNC] = "FUNC",
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[BTF_KIND_FUNC_PROTO] = "FUNC_PROTO",
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};
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static const char *btf__name_in_gobuf(const struct btf *btf,
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@ -167,9 +169,9 @@ static const char * btf__int_encoding_str(uint8_t encoding)
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return "UNKN";
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}
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__attribute ((format (printf, 4, 5)))
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__attribute ((format (printf, 5, 6)))
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static void btf__log_type(const struct btf *btf, const struct btf_type *t,
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bool err, const char *fmt, ...)
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bool err, bool output_cr, const char *fmt, ...)
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{
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uint8_t kind;
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FILE *out;
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@ -193,7 +195,8 @@ static void btf__log_type(const struct btf *btf, const struct btf_type *t,
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va_end(ap);
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}
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fprintf(out, "\n");
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if (output_cr)
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fprintf(out, "\n");
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}
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__attribute ((format (printf, 5, 6)))
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@ -232,6 +235,36 @@ static void btf_log_member(const struct btf *btf,
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fprintf(out, "\n");
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}
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__attribute ((format (printf, 6, 7)))
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static void btf_log_func_param(const struct btf *btf,
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uint32_t name_off, uint32_t type,
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bool err, bool is_last_param,
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const char *fmt, ...)
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{
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FILE *out;
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if (!btf_verbose && !err)
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return;
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out = err ? stderr : stdout;
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if (is_last_param && !type)
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fprintf(out, "vararg)\n");
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else
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fprintf(out, "%u %s%s", type,
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btf__name_in_gobuf(btf, name_off),
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is_last_param ? ")\n" : ", ");
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if (fmt && *fmt) {
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va_list ap;
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fprintf(out, " ");
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va_start(ap, fmt);
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vfprintf(out, fmt, ap);
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va_end(ap);
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}
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}
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int32_t btf__add_base_type(struct btf *btf, const struct base_type *bt)
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{
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struct btf_int_type int_type;
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@ -253,14 +286,14 @@ int32_t btf__add_base_type(struct btf *btf, const struct base_type *bt)
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++btf->type_index;
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if (gobuffer__add(&btf->types, &int_type, sizeof(int_type)) >= 0) {
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btf__log_type(btf, t, false,
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btf__log_type(btf, t, false, true,
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"size=%u bit_offset=%u nr_bits=%u encoding=%s",
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t->size, BTF_INT_OFFSET(int_type.data),
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BTF_INT_BITS(int_type.data),
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btf__int_encoding_str(BTF_INT_ENCODING(int_type.data)));
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return btf->type_index;
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} else {
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btf__log_type(btf, t, true,
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btf__log_type(btf, t, true, true,
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"size=%u bit_offset=%u nr_bits=%u encoding=%s Error in adding gobuffer",
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t->size, BTF_INT_OFFSET(int_type.data),
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BTF_INT_BITS(int_type.data),
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@ -281,13 +314,13 @@ int32_t btf__add_ref_type(struct btf *btf, uint16_t kind, uint32_t type,
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++btf->type_index;
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if (gobuffer__add(&btf->types, &t, sizeof(t)) >= 0) {
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if (kind == BTF_KIND_FWD)
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btf__log_type(btf, &t, false, "%s",
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btf__log_type(btf, &t, false, true, "%s",
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kind_flag ? "union" : "struct");
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else
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btf__log_type(btf, &t, false, "type_id=%u", t.type);
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btf__log_type(btf, &t, false, true, "type_id=%u", t.type);
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return btf->type_index;
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} else {
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btf__log_type(btf, &t, true,
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btf__log_type(btf, &t, true, true,
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"kind_flag=%d type_id=%u Error in adding gobuffer",
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kind_flag, t.type);
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return -1;
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@ -311,12 +344,12 @@ int32_t btf__add_array(struct btf *btf, uint32_t type, uint32_t index_type,
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++btf->type_index;
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if (gobuffer__add(&btf->types, &array_type, sizeof(array_type)) >= 0) {
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btf__log_type(btf, t, false,
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btf__log_type(btf, t, false, true,
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"type_id=%u index_type_id=%u nr_elems=%u",
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array->type, array->index_type, array->nelems);
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return btf->type_index;
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} else {
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btf__log_type(btf, t, true,
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btf__log_type(btf, t, true, true,
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"type_id=%u index_type_id=%u nr_elems=%u Error in adding gobuffer",
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array->type, array->index_type, array->nelems);
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return -1;
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@ -352,11 +385,11 @@ int32_t btf__add_struct(struct btf *btf, uint8_t kind, uint32_t name,
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++btf->type_index;
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if (gobuffer__add(&btf->types, &t, sizeof(t)) >= 0) {
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btf__log_type(btf, &t, false, "kind_flag=%d size=%u vlen=%u",
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btf__log_type(btf, &t, false, true, "kind_flag=%d size=%u vlen=%u",
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kind_flag, t.size, BTF_INFO_VLEN(t.info));
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return btf->type_index;
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} else {
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btf__log_type(btf, &t, true,
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btf__log_type(btf, &t, true, true,
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"kind_flag=%d size=%u vlen=%u Error in adding gobuffer",
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kind_flag, t.size, BTF_INFO_VLEN(t.info));
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return -1;
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@ -374,11 +407,11 @@ int32_t btf__add_enum(struct btf *btf, uint32_t name, uint32_t bit_size,
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++btf->type_index;
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if (gobuffer__add(&btf->types, &t, sizeof(t)) >= 0) {
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btf__log_type(btf, &t, false, "size=%u vlen=%u",
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btf__log_type(btf, &t, false, true, "size=%u vlen=%u",
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t.size, BTF_INFO_VLEN(t.info));
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return btf->type_index;
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} else {
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btf__log_type(btf, &t, true,
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btf__log_type(btf, &t, true, true,
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"size=%u vlen=%u Error in adding gobuffer",
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t.size, BTF_INFO_VLEN(t.info));
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return -1;
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@ -403,6 +436,70 @@ int btf__add_enum_val(struct btf *btf, uint32_t name, int32_t value)
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return 0;
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}
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static int32_t btf__add_func_proto_param(struct btf *btf, uint32_t name,
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uint32_t type, bool is_last_param)
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{
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struct btf_param param;
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param.name_off = name;
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param.type = type;
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if (gobuffer__add(&btf->types, ¶m, sizeof(param)) >= 0) {
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btf_log_func_param(btf, name, type, false, is_last_param, NULL);
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return 0;
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} else {
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btf_log_func_param(btf, name, type, true, is_last_param,
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"Error in adding gobuffer");
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return -1;
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}
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}
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int32_t btf__add_func_proto(struct btf *btf, struct ftype *ftype,
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uint32_t type_id_off)
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{
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uint16_t nr_params, param_idx;
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struct parameter *param;
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struct btf_type t;
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int32_t type_id;
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/* add btf_type for func_proto */
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nr_params = ftype->nr_parms + (ftype->unspec_parms ? 1 : 0);
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t.name_off = 0;
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t.info = BTF_INFO_ENCODE(BTF_KIND_FUNC_PROTO, 0, nr_params);
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t.type = type_id_off + ftype->tag.type;
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++btf->type_index;
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if (gobuffer__add(&btf->types, &t, sizeof(t)) >= 0) {
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btf__log_type(btf, &t, false, false, "return=%u args=(%s",
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t.type, !nr_params ? "void)\n" : "");
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type_id = btf->type_index;
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} else {
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btf__log_type(btf, &t, true, true,
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"return=%u vlen=%u Error in adding gobuffer",
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t.type, BTF_INFO_VLEN(t.info));
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return -1;
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}
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/* add parameters */
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param_idx = 0;
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ftype__for_each_parameter(ftype, param) {
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++param_idx;
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if (btf__add_func_proto_param(btf, param->name,
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type_id_off + param->tag.type,
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param_idx == nr_params))
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return -1;
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}
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++param_idx;
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if (ftype->unspec_parms)
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if (btf__add_func_proto_param(btf, 0, 0,
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param_idx == nr_params))
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return -1;
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return type_id;
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}
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static int btf__write_elf(struct btf *btf)
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{
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GElf_Shdr shdr_mem, *shdr;
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3
libbtf.h
3
libbtf.h
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@ -29,6 +29,7 @@ extern uint8_t btf_verbose;
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#define btf_verbose_log(fmt, ...) { if (btf_verbose) printf(fmt, __VA_ARGS__); }
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struct base_type;
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struct ftype;
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struct btf *btf__new(const char *filename, Elf *elf);
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void btf__free(struct btf *btf);
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@ -45,6 +46,8 @@ int32_t btf__add_array(struct btf *btf, uint32_t type, uint32_t index_type,
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int32_t btf__add_enum(struct btf *btf, uint32_t name, uint32_t size,
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uint16_t nr_entries);
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int btf__add_enum_val(struct btf *btf, uint32_t name, int32_t value);
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int32_t btf__add_func_proto(struct btf *btf, struct ftype *ftype,
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uint32_t type_id_off);
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void btf__set_strings(struct btf *btf, struct gobuffer *strings);
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int btf__encode(struct btf *btf, uint8_t flags);
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