[PATCH bpf-next v8 5/9] bpf: Refactor reporting btf_log_true_size for btf_load

From: Leon Hwang <hidden>
Date: 2026-01-26 15:15:39
Also in: bpf, linux-kselftest, lkml
Subsystem: bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds

In the next commit, it will be able to report logs via extended common
attributes, which will report 'log_true_size' via the extended common
attributes meanwhile.

Therefore, refactor the way of 'btf_log_true_size' reporting in order to
report 'log_true_size' via the extended common attributes easily.

Signed-off-by: Leon Hwang <redacted>
---
 include/linux/bpf_verifier.h |  1 +
 include/linux/btf.h          |  3 ++-
 kernel/bpf/btf.c             | 32 +++++++++-----------------------
 kernel/bpf/log.c             |  9 +++++++++
 kernel/bpf/syscall.c         | 10 +++++++++-
 5 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 7eb024e83d2d..28e22a03ac84 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h

@@ -642,6 +642,7 @@ struct bpf_log_attr {
 
 int bpf_prog_load_log_attr_init(struct bpf_log_attr *log_attr, struct bpf_attrs *attrs,
 				struct bpf_attrs *attrs_common);
+int bpf_btf_load_log_attr_init(struct bpf_log_attr *log_attr, struct bpf_attrs *attrs);
 int bpf_log_attr_finalize(struct bpf_log_attr *log_attr, struct bpf_verifier_log *log);
 
 #define BPF_MAX_SUBPROGS 256

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 48108471c5b1..2812caa6c60e 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h

@@ -145,7 +145,8 @@ const char *btf_get_name(const struct btf *btf);
 void btf_get(struct btf *btf);
 void btf_put(struct btf *btf);
 const struct btf_header *btf_header(const struct btf *btf);
-int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz);
+struct bpf_log_attr;
+int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, struct bpf_log_attr *log_attr);
 struct btf *btf_get_by_fd(int fd);
 int btf_get_info_by_fd(const struct btf *btf,
 		       const union bpf_attr *attr,

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 8959f3bc1e92..3565570601e5 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c

@@ -5856,25 +5856,11 @@ static int btf_check_type_tags(struct btf_verifier_env *env,
 	return 0;
 }
 
-static int finalize_log(struct bpf_verifier_log *log, bpfptr_t uattr, u32 uattr_size)
-{
-	u32 log_true_size;
-	int err;
-
-	err = bpf_vlog_finalize(log, &log_true_size);
-
-	if (uattr_size >= offsetofend(union bpf_attr, btf_log_true_size) &&
-	    copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, btf_log_true_size),
-				  &log_true_size, sizeof(log_true_size)))
-		err = -EFAULT;
-
-	return err;
-}
-
-static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
+static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr,
+			     struct bpf_log_attr *log_attr)
 {
 	bpfptr_t btf_data = make_bpfptr(attr->btf, uattr.is_kernel);
-	char __user *log_ubuf = u64_to_user_ptr(attr->btf_log_buf);
+	char __user *log_ubuf = u64_to_user_ptr(log_attr->log_buf);
 	struct btf_struct_metas *struct_meta_tab;
 	struct btf_verifier_env *env = NULL;
 	struct btf *btf = NULL;

@@ -5891,8 +5877,8 @@ static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uat
 	/* user could have requested verbose verifier output
 	 * and supplied buffer to store the verification trace
 	 */
-	err = bpf_vlog_init(&env->log, attr->btf_log_level,
-			    log_ubuf, attr->btf_log_size);
+	err = bpf_vlog_init(&env->log, log_attr->log_level,
+			    log_ubuf, log_attr->log_size);
 	if (err)
 		goto errout_free;

@@ -5953,7 +5939,7 @@ static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uat
 		}
 	}
 
-	err = finalize_log(&env->log, uattr, uattr_size);
+	err = bpf_log_attr_finalize(log_attr, &env->log);
 	if (err)
 		goto errout_free;

@@ -5965,7 +5951,7 @@ static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uat
 	btf_free_struct_meta_tab(btf);
 errout:
 	/* overwrite err with -ENOSPC or -EFAULT */
-	ret = finalize_log(&env->log, uattr, uattr_size);
+	ret = bpf_log_attr_finalize(log_attr, &env->log);
 	if (ret)
 		err = ret;
 errout_free:

@@ -8136,12 +8122,12 @@ static int __btf_new_fd(struct btf *btf)
 	return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
 }
 
-int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
+int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, struct bpf_log_attr *log_attr)
 {
 	struct btf *btf;
 	int ret;
 
-	btf = btf_parse(attr, uattr, uattr_size);
+	btf = btf_parse(attr, uattr, log_attr);
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);

diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
index c0b816e84384..f1ed24157d71 100644
--- a/kernel/bpf/log.c
+++ b/kernel/bpf/log.c

@@ -902,6 +902,15 @@ int bpf_prog_load_log_attr_init(struct bpf_log_attr *log_attr, struct bpf_attrs
 				 offsetof(union bpf_attr, log_true_size), attrs_common);
 }
 
+int bpf_btf_load_log_attr_init(struct bpf_log_attr *log_attr, struct bpf_attrs *attrs)
+{
+	const union bpf_attr *attr = attrs->attr;
+
+	return bpf_log_attr_init(log_attr, attrs, attr->btf_log_buf, attr->btf_log_size,
+				 attr->btf_log_level, offsetof(union bpf_attr, btf_log_true_size),
+				 NULL);
+}
+
 int bpf_log_attr_finalize(struct bpf_log_attr *log_attr, struct bpf_verifier_log *log)
 {
 	u32 log_true_size, off;

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3d1d1181b9b4..1ed007511776 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c

@@ -5452,6 +5452,9 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
 static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size)
 {
 	struct bpf_token *token = NULL;
+	struct bpf_log_attr log_attr;
+	struct bpf_attrs attrs;
+	int err;
 
 	if (CHECK_ATTR(BPF_BTF_LOAD))
 		return -EINVAL;

@@ -5459,6 +5462,11 @@ static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_
 	if (attr->btf_flags & ~BPF_F_TOKEN_FD)
 		return -EINVAL;
 
+	bpf_attrs_init(&attrs, attr, uattr, uattr_size);
+	err = bpf_btf_load_log_attr_init(&log_attr, &attrs);
+	if (err)
+		return err;
+
 	if (attr->btf_flags & BPF_F_TOKEN_FD) {
 		token = bpf_token_get_from_fd(attr->btf_token_fd);
 		if (IS_ERR(token))

@@ -5476,7 +5484,7 @@ static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_
 
 	bpf_token_put(token);
 
-	return btf_new_fd(attr, uattr, uattr_size);
+	return btf_new_fd(attr, uattr, &log_attr);
 }
 
 #define BPF_BTF_GET_FD_BY_ID_LAST_FIELD fd_by_id_token_fd

-- 
2.52.0

`h`	back out one level
`j`	next message in thread
`k`	previous message in thread
`l`	drill in
`Esc`	close help / fold thread tree
`?`	toggle this help