Expose BTF inline-location information from vmlinux/module .BTF.inline
sections in /sys/kernel/btf using a ".inline" suffix.
vmlinux inline BTF is split relative to vmlinux BTF and can be examined
with:
bpftool btf dump file /sys/kernel/btf/vmlinux.inline
Register the sysfs attribute only when the embedded .BTF.inline section
is non-empty.
Module inline BTF is split relative to the module BTF, which in turn may
be split relative to its distilled base BTF. For example:
bpftool btf dump -B /sys/kernel/btf/vmlinux -B /sys/kernel/btf/xfs \
file /sys/kernel/btf/xfs.inline
Copy the inline BTF data into a private buffer for its sysfs lifetime
and remove the attribute and buffer when the module is unloaded.
Signed-off-by: Alan Maguire <[email protected]>
---
include/linux/btf.h | 1 +
include/linux/module.h | 4 ++
kernel/bpf/Makefile | 1 +
kernel/bpf/btf.c | 109 ++++++++++++++++++++++++++------
kernel/bpf/btf_vmlinux_inline.c | 30 +++++++++
kernel/module/main.c | 4 ++
6 files changed, 128 insertions(+), 21 deletions(-)
create mode 100644 kernel/bpf/btf_vmlinux_inline.c
diff --git a/include/linux/btf.h b/include/linux/btf.h
index a4412bc16688..93f10d3ccabe 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -617,6 +617,7 @@ int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum
bpf_prog_type prog_ty
bool btf_types_are_same(const struct btf *btf1, u32 id1,
const struct btf *btf2, u32 id2);
int btf_check_iter_arg(struct btf *btf, const struct btf_type *func, int
arg_idx);
+struct bin_attribute *sysfs_btf_add(const char *name, void *data, size_t
data_size);
static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct
btf_type *t)
{
diff --git a/include/linux/module.h b/include/linux/module.h
index 7566815fabbe..3d32c4e86f44 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -507,6 +507,10 @@ struct module {
void *btf_data;
void *btf_base_data;
#endif
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF_INLINE)
+ unsigned int btf_inline_data_size;
+ void *btf_inline_data;
+#endif
#ifdef CONFIG_JUMP_LABEL
struct jump_entry *jump_entries;
unsigned int num_jump_entries;
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 9a92c348bbda..60aa5adb0354 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_BPF_SYSCALL) += reuseport_array.o
endif
ifeq ($(CONFIG_SYSFS),y)
obj-$(CONFIG_DEBUG_INFO_BTF) += sysfs_btf.o
+obj-$(CONFIG_DEBUG_INFO_BTF_INLINE) += btf_vmlinux_inline.o
endif
ifeq ($(CONFIG_BPF_JIT),y)
obj-$(CONFIG_BPF_SYSCALL) += bpf_struct_ops.o
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index d74c8668aa3f..3e5890aed2db 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8735,12 +8735,69 @@ enum {
BTF_MODULE_F_LIVE = (1 << 0),
};
+#if IS_ENABLED(CONFIG_SYSFS)
+struct bin_attribute *sysfs_btf_add(const char *name, void *data, size_t
data_size)
+{
+ struct bin_attribute *attr;
+ int err;
+
+ attr = kzalloc_obj(*attr);
+ if (!attr)
+ return ERR_PTR(-ENOMEM);
+
+ sysfs_bin_attr_init(attr);
+ attr->attr.mode = 0444;
+ attr->size = data_size;
+ attr->private = data;
+ attr->read = sysfs_bin_attr_simple_read;
+ attr->attr.name = kstrdup(name, GFP_KERNEL);
+ if (!attr->attr.name) {
+ err = -ENOMEM;
+ goto err_free;
+ }
+ err = sysfs_create_bin_file(btf_kobj, attr);
+ if (err) {
+ pr_warn("failed to register [%s] BTF in sysfs: %d\n", name,
err);
+ goto err_free;
+ }
+ return attr;
+
+err_free:
+ kfree(attr->attr.name);
+ kfree(attr);
+ return ERR_PTR(err);
+}
+
+#else
+struct bin_attribute *sysfs_btf_add(const char *name, void *data, size_t
data_size)
+{
+ return NULL;
+}
+#endif
+
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+#if IS_ENABLED(CONFIG_SYSFS)
+static void sysfs_btf_remove(struct bin_attribute *attr)
+{
+ sysfs_remove_bin_file(btf_kobj, attr);
+ kfree(attr->attr.name);
+ kfree(attr);
+}
+#else
+static void sysfs_btf_remove(struct bin_attribute *attr)
+{
+}
+#endif
+
struct btf_module {
struct list_head list;
struct module *module;
struct btf *btf;
struct bin_attribute *sysfs_attr;
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF_INLINE)
+ struct bin_attribute *sysfs_inline_attr;
+ void *btf_inline_data;
+#endif
int flags;
};
@@ -8754,6 +8811,7 @@ static int btf_module_notify(struct notifier_block *nb,
unsigned long op,
{
struct btf_module *btf_mod, *tmp;
struct module *mod = module;
+ struct bin_attribute *attr;
struct btf *btf;
int err = 0;
@@ -8796,31 +8854,35 @@ static int btf_module_notify(struct notifier_block *nb,
unsigned long op,
list_add(&btf_mod->list, &btf_modules);
mutex_unlock(&btf_module_mutex);
- if (IS_ENABLED(CONFIG_SYSFS)) {
- struct bin_attribute *attr;
-
- attr = kzalloc_obj(*attr);
- if (!attr)
- goto out;
+ attr = sysfs_btf_add(btf->name, btf->data, btf->data_size);
+ if (IS_ERR(attr)) {
+ err = 0;
+ goto out;
+ }
+ btf_mod->sysfs_attr = attr;
- sysfs_bin_attr_init(attr);
- attr->attr.name = btf->name;
- attr->attr.mode = 0444;
- attr->size = btf->data_size;
- attr->private = btf->data;
- attr->read = sysfs_bin_attr_simple_read;
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF_INLINE)
+ if (mod->btf_inline_data_size > 0) {
+ char name[MODULE_NAME_LEN + sizeof(".inline")];
+ void *data;
- err = sysfs_create_bin_file(btf_kobj, attr);
- if (err) {
- pr_warn("failed to register module [%s] BTF in
sysfs: %d\n",
- mod->name, err);
- kfree(attr);
+ data = kvmemdup(mod->btf_inline_data,
mod->btf_inline_data_size,
+ GFP_KERNEL | __GFP_NOWARN);
+ if (!data) {
err = 0;
goto out;
}
-
- btf_mod->sysfs_attr = attr;
+ snprintf(name, sizeof(name), "%s.inline", mod->name);
+ attr = sysfs_btf_add(name, data,
mod->btf_inline_data_size);
+ if (IS_ERR(attr)) {
+ err = 0;
+ kvfree(data);
+ goto out;
+ }
+ btf_mod->btf_inline_data = data;
+ btf_mod->sysfs_inline_attr = attr;
}
+#endif
break;
case MODULE_STATE_LIVE:
@@ -8849,10 +8911,15 @@ static int btf_module_notify(struct notifier_block *nb,
unsigned long op,
btf_free_id(btf_mod->btf);
list_del(&btf_mod->list);
if (btf_mod->sysfs_attr)
- sysfs_remove_bin_file(btf_kobj,
btf_mod->sysfs_attr);
+ sysfs_btf_remove(btf_mod->sysfs_attr);
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF_INLINE)
+ if (btf_mod->sysfs_inline_attr) {
+ sysfs_btf_remove(btf_mod->sysfs_inline_attr);
+ kvfree(btf_mod->btf_inline_data);
+ }
+#endif
purge_cand_cache(btf_mod->btf);
btf_put(btf_mod->btf);
- kfree(btf_mod->sysfs_attr);
kfree(btf_mod);
break;
}
diff --git a/kernel/bpf/btf_vmlinux_inline.c b/kernel/bpf/btf_vmlinux_inline.c
new file mode 100644
index 000000000000..b155df9849b9
--- /dev/null
+++ b/kernel/bpf/btf_vmlinux_inline.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026, Oracle and/or its affiliates. */
+/*
+ * Provide kernel BTF inline function information for use by BPF tools.
+ */
+#include <linux/btf.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#if IS_BUILTIN(CONFIG_DEBUG_INFO_BTF_INLINE)
+extern char __start_BTF_inline[];
+extern char __stop_BTF_inline[];
+#endif
+
+static int __init btf_vmlinux_inline_init(void)
+{
+#if IS_BUILTIN(CONFIG_DEBUG_INFO_BTF_INLINE)
+ size_t data_size = __stop_BTF_inline - __start_BTF_inline;
+
+ if (data_size)
+ sysfs_btf_add("vmlinux.inline", __start_BTF_inline,
+ data_size);
+#endif
+ return 0;
+}
+subsys_initcall(btf_vmlinux_inline_init);
+
+MODULE_DESCRIPTION("BTF inline information for vmlinux");
+MODULE_LICENSE("GPL");
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 46dd8d25a605..7e06ef113113 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2712,6 +2712,10 @@ static int find_module_sections(struct module *mod,
struct load_info *info)
mod->btf_base_data = any_section_objs(info, ".BTF.base", 1,
&mod->btf_base_data_size);
#endif
+#if IS_ENABLED(CONFIG_DEBUG_INFO_BTF_INLINE)
+ mod->btf_inline_data = any_section_objs(info, ".BTF.inline", 1,
+ &mod->btf_inline_data_size);
+#endif
#ifdef CONFIG_JUMP_LABEL
mod->jump_entries = section_objs(info, "__jump_table",
sizeof(*mod->jump_entries),
--
2.43.5
