btf: Allow multiple cu's in dwarf->btf conversion
Currently, the pahole dwarf->btf conversion only supports one
compilation unit. This is not ideal since we would like using pahole to
generate BTF for vmlinux which has a lot of compilation units.
This patch added support to process multiple compilation units per ELF
file. Multiple ELF files are also supported properly.
The following is a demonstration example:
-bash-4.4$ cat t1.c
struct t1 {
int a1;
} g1;
int main(void) { return 0; }
-bash-4.4$ cat t2.c
struct t2 {
char a2;
} g2;
int main() { return 0; }
-bash-4.4$ cat t3.c
struct t3 {
unsigned char a1:4;
} g1;
int main(void) { return 0; }
-bash-4.4$ cat t4.c
struct t4 {
volatile char a4;
} g2;
int main() { return 0; }
-bash-4.4$ gcc -O2 -o t1 -g t1.c t2.c
-bash-4.4$ gcc -O2 -o t3 -g t3.c t4.c
Note that both the binary "t1" and "t3" have two compilation units in
their respective dwarf debug_info sections. The following is the pahole
verbose output for BTF conversion for these two binaries.
-bash-4.4$ pahole -JV t1 t3
File t1:
[1] STRUCT t1 size=4 vlen=1
a1 type_id=2 bits_offset=0
[2] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
[3] STRUCT t2 size=1 vlen=1
a2 type_id=4 bits_offset=0
[4] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[5] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
File t3:
[1] STRUCT t3 size=1 vlen=1
a1 type_id=3 bits_offset=0
[2] INT unsigned char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[3] INT unsigned char size=1 bit_offset=0 nr_bits=4 encoding=(none)
[4] INT (anon) size=4 bit_offset=0 nr_bits=32 encoding=(none)
[5] STRUCT t4 size=1 vlen=1
a4 type_id=6 bits_offset=0
[6] VOLATILE (anon) type_id=7
[7] INT char size=1 bit_offset=0 nr_bits=8 encoding=(none)
[8] INT int size=4 bit_offset=0 nr_bits=32 encoding=SIGNED
Signed-off-by: Andrii Nakryiko <andriin@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>
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Andrii Nakryiko
Arnaldo Carvalho de Melo
parent
d843945ba5
commit
65bd17abc7
112
btf_encoder.c
112
btf_encoder.c
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@ -8,19 +8,22 @@
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#include <inttypes.h>
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static int tag__check_id_drift(const struct tag *tag,
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uint32_t core_id, uint32_t btf_type_id)
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uint32_t core_id, uint32_t btf_type_id,
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uint32_t type_id_off)
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{
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if (btf_type_id != core_id) {
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fprintf(stderr, "%s: %s id drift, core_id: %u, btf_type_id: %u\n",
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if (btf_type_id != (core_id + type_id_off)) {
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fprintf(stderr,
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"%s: %s id drift, core_id: %u, btf_type_id: %u, type_id_off: %u\n",
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__func__, dwarf_tag_name(tag->tag),
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core_id, btf_type_id);
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core_id, btf_type_id, type_id_off);
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return -1;
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}
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return 0;
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}
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static int32_t structure_type__encode(struct btf *btf, struct tag *tag)
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static int32_t structure_type__encode(struct btf *btf, struct tag *tag,
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uint32_t type_id_off)
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{
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struct type *type = tag__type(tag);
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struct class_member *pos;
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@ -59,7 +62,8 @@ static int32_t structure_type__encode(struct btf *btf, struct tag *tag)
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pos->bitfield_offset -
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pos->bitfield_size;
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if (btf__add_member(btf, pos->name, pos->tag.type,
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if (btf__add_member(btf, pos->name,
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type_id_off + pos->tag.type,
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bit_offset))
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return -1;
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}
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@ -107,21 +111,24 @@ static int32_t enumeration_type__encode(struct btf *btf, struct tag *tag)
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}
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static int tag__encode_btf(struct tag *tag, uint32_t core_id, struct btf *btf,
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uint32_t array_index_id)
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uint32_t array_index_id, uint32_t type_id_off)
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{
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/* single out type 0 as it represents special type "void" */
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uint32_t ref_type_id = tag->type == 0 ? 0 : type_id_off + tag->type;
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switch (tag->tag) {
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case DW_TAG_base_type:
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return btf__add_base_type(btf, tag__base_type(tag));
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case DW_TAG_const_type:
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return btf__add_ref_type(btf, BTF_KIND_CONST, tag->type, 0);
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return btf__add_ref_type(btf, BTF_KIND_CONST, ref_type_id, 0);
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case DW_TAG_pointer_type:
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return btf__add_ref_type(btf, BTF_KIND_PTR, tag->type, 0);
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return btf__add_ref_type(btf, BTF_KIND_PTR, ref_type_id, 0);
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case DW_TAG_restrict_type:
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return btf__add_ref_type(btf, BTF_KIND_RESTRICT, tag->type, 0);
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return btf__add_ref_type(btf, BTF_KIND_RESTRICT, ref_type_id, 0);
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case DW_TAG_volatile_type:
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return btf__add_ref_type(btf, BTF_KIND_VOLATILE, tag->type, 0);
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return btf__add_ref_type(btf, BTF_KIND_VOLATILE, ref_type_id, 0);
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case DW_TAG_typedef:
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return btf__add_ref_type(btf, BTF_KIND_TYPEDEF, tag->type,
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return btf__add_ref_type(btf, BTF_KIND_TYPEDEF, ref_type_id,
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tag__namespace(tag)->name);
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case DW_TAG_structure_type:
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case DW_TAG_union_type:
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@ -130,9 +137,9 @@ static int tag__encode_btf(struct tag *tag, uint32_t core_id, struct btf *btf,
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return btf__add_ref_type(btf, BTF_KIND_FWD, 0,
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tag__namespace(tag)->name);
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else
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return structure_type__encode(btf, tag);
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return structure_type__encode(btf, tag, type_id_off);
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case DW_TAG_array_type:
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return btf__add_array(btf, tag->type, array_index_id,
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return btf__add_array(btf, ref_type_id, array_index_id,
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/*TODO: Encode one dimension
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* at a time.
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*/
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@ -157,40 +164,72 @@ static int tag__encode_btf(struct tag *tag, uint32_t core_id, struct btf *btf,
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*/
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extern struct strings *strings;
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int cu__encode_btf(struct cu *cu, int verbose)
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static struct btf *btf;
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static uint32_t array_index_id;
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int btf_encoder__encode()
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{
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struct btf *btf = btf__new(cu->filename, cu->elf);
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struct tag *pos;
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uint32_t core_id, array_index_id;
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uint16_t id;
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int err;
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err = btf__encode(btf, 0);
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btf__free(btf);
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btf = NULL;
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return err;
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}
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int cu__encode_btf(struct cu *cu, int verbose)
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{
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bool add_index_type = false;
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uint32_t type_id_off;
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uint32_t core_id;
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struct tag *pos;
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int err = 0;
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if (btf && strcmp(btf->filename, cu->filename)) {
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err = btf_encoder__encode();
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if (err)
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goto out;
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/* Finished one file, add one empty line */
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if (verbose)
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printf("\n");
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}
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if (!btf) {
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btf = btf__new(cu->filename, cu->elf);
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if (!btf)
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return -1;
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btf__set_strings(btf, &strings->gb);
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/* cu__find_base_type_by_name() takes "uint16_t *id" */
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uint16_t id;
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if (!cu__find_base_type_by_name(cu, "int", &id)) {
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add_index_type = true;
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id = cu->types_table.nr_entries;
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}
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array_index_id = id;
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if (verbose)
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printf("File %s:\n", btf->filename);
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}
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btf_verbose = verbose;
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if (btf == NULL)
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return -1;
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btf__set_strings(btf, &strings->gb);
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/* cu__find_base_type_by_name() takes "uint16_t *id" */
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if (!cu__find_base_type_by_name(cu, "int", &id))
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id = cu->types_table.nr_entries;
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array_index_id = id;
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type_id_off = btf->type_index;
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cu__for_each_type(cu, core_id, pos) {
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int32_t btf_type_id = tag__encode_btf(pos, core_id, btf,
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array_index_id);
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array_index_id,
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type_id_off);
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if (btf_type_id < 0 ||
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tag__check_id_drift(pos, core_id, btf_type_id)) {
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tag__check_id_drift(pos, core_id, btf_type_id, type_id_off)) {
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err = -1;
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goto out;
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}
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id = btf_type_id;
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}
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if (array_index_id == cu->types_table.nr_entries) {
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if (add_index_type) {
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struct base_type bt = {};
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bt.name = 0;
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@ -198,11 +237,8 @@ int cu__encode_btf(struct cu *cu, int verbose)
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btf__add_base_type(btf, &bt);
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}
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err = btf__encode(btf, 0);
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out:
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btf__free(btf);
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if (err)
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fprintf(stderr, "Failed to encode BTF\n");
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btf__free(btf);
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return err;
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}
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@ -3,6 +3,8 @@
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struct cu;
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int btf_encoder__encode();
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int cu__encode_btf(struct cu *cu, int verbose);
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#endif /* _BTF_ENCODER_H_ */
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2
libbtf.c
2
libbtf.c
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@ -509,7 +509,7 @@ int btf__encode(struct btf *btf, uint8_t flags)
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hdr = btf->hdr;
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hdr->magic = BTF_MAGIC;
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hdr->version = 1;
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hdr->flags = 0;
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hdr->flags = flags;
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hdr->hdr_len = sizeof(*hdr);
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hdr->type_off = 0;
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10
pahole.c
10
pahole.c
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@ -1115,7 +1115,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu,
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if (btf_encode) {
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cu__encode_btf(cu, global_verbose);
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goto dump_and_stop;
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return LSK__KEEPIT;
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}
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if (ctf_encode) {
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@ -1265,6 +1265,14 @@ int main(int argc, char *argv[])
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goto out_cus_delete;
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}
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if (btf_encode) {
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err = btf_encoder__encode();
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if (err) {
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fputs("Failed to encode BTF\n", stderr);
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goto out_cus_delete;
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}
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}
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if (stats_formatter != NULL)
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print_stats();
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rc = EXIT_SUCCESS;
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