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-rw-r--r--tools/lib/bpf/libbpf.c174
1 files changed, 162 insertions, 12 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e1615c274250..7aad78dbb4b4 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -186,6 +186,7 @@ enum reloc_type {
RELO_CALL,
RELO_DATA,
RELO_EXTERN_VAR,
+ RELO_EXTERN_FUNC,
RELO_SUBPROG_ADDR,
};
@@ -1955,6 +1956,11 @@ static const char *btf_kind_str(const struct btf_type *t)
return __btf_kind_str(btf_kind(t));
}
+static enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
+{
+ return (enum btf_func_linkage)BTF_INFO_VLEN(t->info);
+}
+
/*
* Fetch integer attribute of BTF map definition. Such attributes are
* represented using a pointer to an array, in which dimensionality of array
@@ -3019,7 +3025,7 @@ static bool sym_is_subprog(const GElf_Sym *sym, int text_shndx)
static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
{
const struct btf_type *t;
- const char *var_name;
+ const char *tname;
int i, n;
if (!btf)
@@ -3029,14 +3035,18 @@ static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
for (i = 1; i <= n; i++) {
t = btf__type_by_id(btf, i);
- if (!btf_is_var(t))
+ if (!btf_is_var(t) && !btf_is_func(t))
continue;
- var_name = btf__name_by_offset(btf, t->name_off);
- if (strcmp(var_name, ext_name))
+ tname = btf__name_by_offset(btf, t->name_off);
+ if (strcmp(tname, ext_name))
continue;
- if (btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
+ if (btf_is_var(t) &&
+ btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
+ return -EINVAL;
+
+ if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
return -EINVAL;
return i;
@@ -3149,12 +3159,48 @@ static int find_int_btf_id(const struct btf *btf)
return 0;
}
+static int add_dummy_ksym_var(struct btf *btf)
+{
+ int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
+ const struct btf_var_secinfo *vs;
+ const struct btf_type *sec;
+
+ sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
+ BTF_KIND_DATASEC);
+ if (sec_btf_id < 0)
+ return 0;
+
+ sec = btf__type_by_id(btf, sec_btf_id);
+ vs = btf_var_secinfos(sec);
+ for (i = 0; i < btf_vlen(sec); i++, vs++) {
+ const struct btf_type *vt;
+
+ vt = btf__type_by_id(btf, vs->type);
+ if (btf_is_func(vt))
+ break;
+ }
+
+ /* No func in ksyms sec. No need to add dummy var. */
+ if (i == btf_vlen(sec))
+ return 0;
+
+ int_btf_id = find_int_btf_id(btf);
+ dummy_var_btf_id = btf__add_var(btf,
+ "dummy_ksym",
+ BTF_VAR_GLOBAL_ALLOCATED,
+ int_btf_id);
+ if (dummy_var_btf_id < 0)
+ pr_warn("cannot create a dummy_ksym var\n");
+
+ return dummy_var_btf_id;
+}
+
static int bpf_object__collect_externs(struct bpf_object *obj)
{
struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
const struct btf_type *t;
struct extern_desc *ext;
- int i, n, off;
+ int i, n, off, dummy_var_btf_id;
const char *ext_name, *sec_name;
Elf_Scn *scn;
GElf_Shdr sh;
@@ -3166,6 +3212,10 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
if (elf_sec_hdr(obj, scn, &sh))
return -LIBBPF_ERRNO__FORMAT;
+ dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
+ if (dummy_var_btf_id < 0)
+ return dummy_var_btf_id;
+
n = sh.sh_size / sh.sh_entsize;
pr_debug("looking for externs among %d symbols...\n", n);
@@ -3210,6 +3260,11 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
sec_name = btf__name_by_offset(obj->btf, sec->name_off);
if (strcmp(sec_name, KCONFIG_SEC) == 0) {
+ if (btf_is_func(t)) {
+ pr_warn("extern function %s is unsupported under %s section\n",
+ ext->name, KCONFIG_SEC);
+ return -ENOTSUP;
+ }
kcfg_sec = sec;
ext->type = EXT_KCFG;
ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
@@ -3231,6 +3286,11 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
return -ENOTSUP;
}
} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
+ if (btf_is_func(t) && ext->is_weak) {
+ pr_warn("extern weak function %s is unsupported\n",
+ ext->name);
+ return -ENOTSUP;
+ }
ksym_sec = sec;
ext->type = EXT_KSYM;
skip_mods_and_typedefs(obj->btf, t->type,
@@ -3257,7 +3317,14 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
* extern variables in DATASEC
*/
int int_btf_id = find_int_btf_id(obj->btf);
+ /* For extern function, a dummy_var added earlier
+ * will be used to replace the vs->type and
+ * its name string will be used to refill
+ * the missing param's name.
+ */
+ const struct btf_type *dummy_var;
+ dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type != EXT_KSYM)
@@ -3276,12 +3343,32 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
ext_name = btf__name_by_offset(obj->btf, vt->name_off);
ext = find_extern_by_name(obj, ext_name);
if (!ext) {
- pr_warn("failed to find extern definition for BTF var '%s'\n",
- ext_name);
+ pr_warn("failed to find extern definition for BTF %s '%s'\n",
+ btf_kind_str(vt), ext_name);
return -ESRCH;
}
- btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
- vt->type = int_btf_id;
+ if (btf_is_func(vt)) {
+ const struct btf_type *func_proto;
+ struct btf_param *param;
+ int j;
+
+ func_proto = btf__type_by_id(obj->btf,
+ vt->type);
+ param = btf_params(func_proto);
+ /* Reuse the dummy_var string if the
+ * func proto does not have param name.
+ */
+ for (j = 0; j < btf_vlen(func_proto); j++)
+ if (param[j].type && !param[j].name_off)
+ param[j].name_off =
+ dummy_var->name_off;
+ vs->type = dummy_var_btf_id;
+ vt->info &= ~0xffff;
+ vt->info |= BTF_FUNC_GLOBAL;
+ } else {
+ btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+ vt->type = int_btf_id;
+ }
vs->offset = off;
vs->size = sizeof(int);
}
@@ -3436,7 +3523,10 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
}
pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
prog->name, i, ext->name, ext->sym_idx, insn_idx);
- reloc_desc->type = RELO_EXTERN_VAR;
+ if (insn->code == (BPF_JMP | BPF_CALL))
+ reloc_desc->type = RELO_EXTERN_FUNC;
+ else
+ reloc_desc->type = RELO_EXTERN_VAR;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = i; /* sym_off stores extern index */
return 0;
@@ -6241,6 +6331,12 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
}
relo->processed = true;
break;
+ case RELO_EXTERN_FUNC:
+ ext = &obj->externs[relo->sym_off];
+ insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
+ insn[0].imm = ext->ksym.kernel_btf_id;
+ relo->processed = true;
+ break;
case RELO_SUBPROG_ADDR:
insn[0].src_reg = BPF_PSEUDO_FUNC;
/* will be handled as a follow up pass */
@@ -7361,6 +7457,7 @@ static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
{
char sym_type, sym_name[500];
unsigned long long sym_addr;
+ const struct btf_type *t;
struct extern_desc *ext;
int ret, err = 0;
FILE *f;
@@ -7387,6 +7484,10 @@ static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
if (!ext || ext->type != EXT_KSYM)
continue;
+ t = btf__type_by_id(obj->btf, ext->btf_id);
+ if (!btf_is_var(t))
+ continue;
+
if (ext->is_set && ext->ksym.addr != sym_addr) {
pr_warn("extern (ksym) '%s' resolution is ambiguous: 0x%llx or 0x%llx\n",
sym_name, ext->ksym.addr, sym_addr);
@@ -7488,8 +7589,53 @@ static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
return 0;
}
+static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj,
+ struct extern_desc *ext)
+{
+ int local_func_proto_id, kfunc_proto_id, kfunc_id;
+ const struct btf_type *kern_func;
+ struct btf *kern_btf = NULL;
+ int ret, kern_btf_fd = 0;
+
+ local_func_proto_id = ext->ksym.type_id;
+
+ kfunc_id = find_ksym_btf_id(obj, ext->name, BTF_KIND_FUNC,
+ &kern_btf, &kern_btf_fd);
+ if (kfunc_id < 0) {
+ pr_warn("extern (func ksym) '%s': not found in kernel BTF\n",
+ ext->name);
+ return kfunc_id;
+ }
+
+ if (kern_btf != obj->btf_vmlinux) {
+ pr_warn("extern (func ksym) '%s': function in kernel module is not supported\n",
+ ext->name);
+ return -ENOTSUP;
+ }
+
+ kern_func = btf__type_by_id(kern_btf, kfunc_id);
+ kfunc_proto_id = kern_func->type;
+
+ ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id,
+ kern_btf, kfunc_proto_id);
+ if (ret <= 0) {
+ pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with kernel [%d]\n",
+ ext->name, local_func_proto_id, kfunc_proto_id);
+ return -EINVAL;
+ }
+
+ ext->is_set = true;
+ ext->ksym.kernel_btf_obj_fd = kern_btf_fd;
+ ext->ksym.kernel_btf_id = kfunc_id;
+ pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n",
+ ext->name, kfunc_id);
+
+ return 0;
+}
+
static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
{
+ const struct btf_type *t;
struct extern_desc *ext;
int i, err;
@@ -7498,7 +7644,11 @@ static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
if (ext->type != EXT_KSYM || !ext->ksym.type_id)
continue;
- err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
+ t = btf__type_by_id(obj->btf, ext->btf_id);
+ if (btf_is_var(t))
+ err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
+ else
+ err = bpf_object__resolve_ksym_func_btf_id(obj, ext);
if (err)
return err;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-18 18:21:19 +0000