From: Ihor Solodrai <ihor.solodrai@xxxxx>
btf_encoder__tag_kfuncs() is a post-processing step of BTF encoding,
executed right before BTF is deduped and dumped to the output.
Split btf_encoder__tag_kfuncs() routine in two parts:
* btf_encoder__collect_kfuncs()
* btf_encoder__tag_kfuncs()
btf_encoder__collect_kfuncs() reads the .BTF_ids section of the ELF,
collecting kfunc information into a list of kfunc_info structs in the
btf_encoder. It is executed in btf_encoder__new() when tag_kfuncs flag
is set. This way kfunc information is available during entire lifetime
of the btf_encoder.
btf_encoder__tag_kfuncs() is basically the same: collect BTF
functions, and then for each kfunc find and tag correspoding BTF
func. Except now kfunc information is not collected in-place, but is
simply read from the btf_encoder.
Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxxxxxx>
---
btf_encoder.c | 89 +++++++++++++++++++++++++++++++++++++++------------
1 file changed, 68 insertions(+), 21 deletions(-)
diff --git a/btf_encoder.c b/btf_encoder.c
index 511c1ea..e9f4baf 100644
--- a/btf_encoder.c
+++ b/btf_encoder.c
@@ -89,6 +89,7 @@ struct elf_function {
const char *name;
char *alias;
size_t prefixlen;
+ bool kfunc;
};
struct elf_secinfo {
@@ -100,6 +101,13 @@ struct elf_secinfo {
struct gobuffer secinfo;
};
+struct kfunc_info {
+ struct list_head node;
+ uint32_t id;
+ uint32_t flags;
+ const char* name;
+};
+
struct elf_functions {
struct list_head node; /* for elf_functions_list */
Elf *elf; /* source ELF */
@@ -143,6 +151,7 @@ struct btf_encoder {
* so we have to store elf_functions tables per ELF.
*/
struct list_head elf_functions_list;
+ struct list_head kfuncs; /* list of kfunc_info */
};
struct btf_func {
@@ -1842,9 +1851,9 @@ static int btf__add_kfunc_decl_tag(struct btf *btf, const char *tag, __u32 id, c
return 0;
}
-static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *funcs, const char *kfunc, __u32 flags)
+static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *funcs, const struct kfunc_info *kfunc)
{
- struct btf_func key = { .name = kfunc };
+ struct btf_func key = { .name = kfunc->name };
struct btf *btf = encoder->btf;
struct btf_func *target;
const void *base;
@@ -1855,7 +1864,7 @@ static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *
cnt = gobuffer__nr_entries(funcs);
target = bsearch(&key, base, cnt, sizeof(key), btf_func_cmp);
if (!target) {
- fprintf(stderr, "%s: failed to find kfunc '%s' in BTF\n", __func__, kfunc);
+ fprintf(stderr, "%s: failed to find kfunc '%s' in BTF\n", __func__, kfunc->name);
return -1;
}
@@ -1864,11 +1873,12 @@ static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *
* We are ok to do this b/c we will later btf__dedup() to remove
* any duplicates.
*/
- err = btf__add_kfunc_decl_tag(btf, BTF_KFUNC_TYPE_TAG, target->type_id, kfunc);
+ err = btf__add_kfunc_decl_tag(btf, BTF_KFUNC_TYPE_TAG, target->type_id, kfunc->name);
if (err < 0)
return err;
- if (flags & KF_FASTCALL) {
- err = btf__add_kfunc_decl_tag(btf, BTF_FASTCALL_TAG, target->type_id, kfunc);
+
+ if (kfunc->flags & KF_FASTCALL) {
+ err = btf__add_kfunc_decl_tag(btf, BTF_FASTCALL_TAG, target->type_id, kfunc->name);
if (err < 0)
return err;
}
@@ -1876,11 +1886,10 @@ static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *
return 0;
}
-static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
+static int btf_encoder__collect_kfuncs(struct btf_encoder *encoder)
{
const char *filename = encoder->source_filename;
struct gobuffer btf_kfunc_ranges = {};
- struct gobuffer btf_funcs = {};
Elf_Data *symbols = NULL;
Elf_Data *idlist = NULL;
Elf_Scn *symscn = NULL;
@@ -1897,6 +1906,8 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
int nr_syms;
int i = 0;
+ INIT_LIST_HEAD(&encoder->kfuncs);
+
fd = open(filename, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "Cannot open %s\n", filename);
@@ -1977,12 +1988,6 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
}
nr_syms = shdr.sh_size / shdr.sh_entsize;
- err = btf_encoder__collect_btf_funcs(encoder, &btf_funcs);
- if (err) {
- fprintf(stderr, "%s: failed to collect BTF funcs\n", __func__);
- goto out;
- }
-
/* First collect all kfunc set ranges.
*
* Note we choose not to sort these ranges and accept a linear
@@ -2015,12 +2020,13 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
for (i = 0; i < nr_syms; i++) {
const struct btf_kfunc_set_range *ranges;
const struct btf_id_and_flag *pair;
+ struct elf_function *elf_fn;
+ struct kfunc_info *kfunc;
unsigned int ranges_cnt;
char *func, *name;
ptrdiff_t off;
GElf_Sym sym;
bool found;
- int err;
int j;
if (!gelf_getsym(symbols, i, &sym)) {
@@ -2061,18 +2067,26 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
continue;
}
- err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func, pair->flags);
- if (err) {
- fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func);
- free(func);
+ elf_fn = btf_encoder__find_function(encoder, func, 0);
+ free(func);
+ if (!elf_fn)
+ continue;
+ elf_fn->kfunc = true;
+
+ kfunc = calloc(1, sizeof(*kfunc));
+ if (!kfunc) {
+ fprintf(stderr, "%s: failed to allocate memory for kfunc info\n", __func__);
+ err = -ENOMEM;
goto out;
}
- free(func);
+ kfunc->id = pair->id;
+ kfunc->flags = pair->flags;
+ kfunc->name = elf_fn->name;
+ list_add(&kfunc->node, &encoder->kfuncs);
}
err = 0;
out:
- __gobuffer__delete(&btf_funcs);
__gobuffer__delete(&btf_kfunc_ranges);
if (elf)
elf_end(elf);
@@ -2081,6 +2095,34 @@ out:
return err;
}
+static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
+{
+ struct gobuffer btf_funcs = {};
+ int err;
+
+ err = btf_encoder__collect_btf_funcs(encoder, &btf_funcs);
+ if (err) {
+ fprintf(stderr, "%s: failed to collect BTF funcs\n", __func__);
+ goto out;
+ }
+
+ struct kfunc_info *kfunc, *tmp;
+ list_for_each_entry_safe(kfunc, tmp, &encoder->kfuncs, node) {
+ err = btf_encoder__tag_kfunc(encoder, &btf_funcs, kfunc);
+ if (err) {
+ fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, kfunc->name);
+ goto out;
+ }
+ list_del(&kfunc->node);
+ free(kfunc);
+ }
+
+ err = 0;
+out:
+ __gobuffer__delete(&btf_funcs);
+ return err;
+}
+
int btf_encoder__encode(struct btf_encoder *encoder, struct conf_load *conf)
{
bool should_tag_kfuncs;
@@ -2496,6 +2538,11 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
if (!found_percpu && encoder->verbose)
printf("%s: '%s' doesn't have '%s' section\n", __func__, cu->filename, PERCPU_SECTION);
+ if (encoder->tag_kfuncs) {
+ if (btf_encoder__collect_kfuncs(encoder))
+ goto out_delete;
+ }
+
if (encoder->verbose)
printf("File %s:\n", cu->filename);
}
--
2.48.1
