From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] bpf/btf: Move tracing BTF APIs to the BTF library
Date: Wed, 15 Jul 2026 10:53:14 +0900 [thread overview]
Message-ID: <20260715105314.5708c8ab918718942fb5b31e@kernel.org> (raw)
In-Reply-To: <20260714103401.0aa3f9e0@gandalf.local.home>
On Tue, 14 Jul 2026 10:34:01 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
>
> Whatever happened to this patch?
IIRC, this got rejected, so we ended up having
to keep maintaining it within the trace.
(because bpf does not use these functions.)
Thanks,
>
> -- Steve
>
>
> On Tue, 10 Oct 2023 22:54:19 +0900
> "Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
>
> > From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> >
> > Move the BTF APIs used in tracing to the BTF library code for sharing it
> > with others.
> > Previously, to avoid complex dependency in a series I made it on the
> > tracing tree, but now it is a good time to move it to BPF tree because
> > these functions are pure BTF functions.
> >
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > ---
> > include/linux/btf.h | 24 +++++++++
> > kernel/bpf/btf.c | 115 +++++++++++++++++++++++++++++++++++++++++
> > kernel/trace/Makefile | 1
> > kernel/trace/trace_btf.c | 122 --------------------------------------------
> > kernel/trace/trace_btf.h | 11 ----
> > kernel/trace/trace_probe.c | 2 -
> > 6 files changed, 140 insertions(+), 135 deletions(-)
> > delete mode 100644 kernel/trace/trace_btf.c
> > delete mode 100644 kernel/trace/trace_btf.h
> >
> > diff --git a/include/linux/btf.h b/include/linux/btf.h
> > index 928113a80a95..8372d93ea402 100644
> > --- a/include/linux/btf.h
> > +++ b/include/linux/btf.h
> > @@ -507,6 +507,14 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
> > int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
> > bool btf_types_are_same(const struct btf *btf1, u32 id1,
> > const struct btf *btf2, u32 id2);
> > +const struct btf_type *btf_find_func_proto(const char *func_name,
> > + struct btf **btf_p);
> > +const struct btf_param *btf_get_func_param(const struct btf_type *func_proto,
> > + s32 *nr);
> > +const struct btf_member *btf_find_struct_member(struct btf *btf,
> > + const struct btf_type *type,
> > + const char *member_name,
> > + u32 *anon_offset);
> > #else
> > static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
> > u32 type_id)
> > @@ -559,6 +567,22 @@ static inline bool btf_types_are_same(const struct btf *btf1, u32 id1,
> > {
> > return false;
> > }
> > +static inline const struct btf_type *btf_find_func_proto(const char *func_name,
> > + struct btf **btf_p)
> > +{
> > + return NULL;
> > +}
> > +static inline const struct btf_param *
> > +btf_get_func_param(const struct btf_type *func_proto, s32 *nr)
> > +{
> > + return NULL;
> > +}
> > +static inline const struct btf_member *
> > +btf_find_struct_member(struct btf *btf, const struct btf_type *type,
> > + const char *member_name, u32 *anon_offset)
> > +{
> > + return NULL;
> > +}
> > #endif
> >
> > static inline bool btf_type_is_struct_ptr(struct btf *btf, const struct btf_type *t)
> > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > index 8090d7fb11ef..e5cbf3b31b78 100644
> > --- a/kernel/bpf/btf.c
> > +++ b/kernel/bpf/btf.c
> > @@ -912,6 +912,121 @@ static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
> > return t;
> > }
> >
> > +/*
> > + * Find a function proto type by name, and return the btf_type with its btf
> > + * in *@btf_p. Return NULL if not found.
> > + * Note that caller has to call btf_put(*@btf_p) after using the btf_type.
> > + */
> > +const struct btf_type *btf_find_func_proto(const char *func_name, struct btf **btf_p)
> > +{
> > + const struct btf_type *t;
> > + s32 id;
> > +
> > + id = bpf_find_btf_id(func_name, BTF_KIND_FUNC, btf_p);
> > + if (id < 0)
> > + return NULL;
> > +
> > + /* Get BTF_KIND_FUNC type */
> > + t = btf_type_by_id(*btf_p, id);
> > + if (!t || !btf_type_is_func(t))
> > + goto err;
> > +
> > + /* The type of BTF_KIND_FUNC is BTF_KIND_FUNC_PROTO */
> > + t = btf_type_by_id(*btf_p, t->type);
> > + if (!t || !btf_type_is_func_proto(t))
> > + goto err;
> > +
> > + return t;
> > +err:
> > + btf_put(*btf_p);
> > + return NULL;
> > +}
> > +
> > +/*
> > + * Get function parameter with the number of parameters.
> > + * This can return NULL if the function has no parameters.
> > + * It can return -EINVAL if the @func_proto is not a function proto type.
> > + */
> > +const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s32 *nr)
> > +{
> > + if (!btf_type_is_func_proto(func_proto))
> > + return ERR_PTR(-EINVAL);
> > +
> > + *nr = btf_type_vlen(func_proto);
> > + if (*nr > 0)
> > + return (const struct btf_param *)(func_proto + 1);
> > + else
> > + return NULL;
> > +}
> > +
> > +#define BTF_ANON_STACK_MAX 16
> > +
> > +struct btf_anon_stack {
> > + u32 tid;
> > + u32 offset;
> > +};
> > +
> > +/*
> > + * Find a member of data structure/union by name and return it.
> > + * Return NULL if not found, or -EINVAL if parameter is invalid.
> > + * If the member is an member of anonymous union/structure, the offset
> > + * of that anonymous union/structure is stored into @anon_offset. Caller
> > + * can calculate the correct offset from the root data structure by
> > + * adding anon_offset to the member's offset.
> > + */
> > +const struct btf_member *btf_find_struct_member(struct btf *btf,
> > + const struct btf_type *type,
> > + const char *member_name,
> > + u32 *anon_offset)
> > +{
> > + struct btf_anon_stack *anon_stack;
> > + const struct btf_member *member;
> > + u32 tid, cur_offset = 0;
> > + const char *name;
> > + int i, top = 0;
> > +
> > + anon_stack = kcalloc(BTF_ANON_STACK_MAX, sizeof(*anon_stack), GFP_KERNEL);
> > + if (!anon_stack)
> > + return ERR_PTR(-ENOMEM);
> > +
> > +retry:
> > + if (!btf_type_is_struct(type)) {
> > + member = ERR_PTR(-EINVAL);
> > + goto out;
> > + }
> > +
> > + for_each_member(i, type, member) {
> > + if (!member->name_off) {
> > + /* Anonymous union/struct: push it for later use */
> > + type = btf_type_skip_modifiers(btf, member->type, &tid);
> > + if (type && top < BTF_ANON_STACK_MAX) {
> > + anon_stack[top].tid = tid;
> > + anon_stack[top++].offset =
> > + cur_offset + member->offset;
> > + }
> > + } else {
> > + name = btf_name_by_offset(btf, member->name_off);
> > + if (name && !strcmp(member_name, name)) {
> > + if (anon_offset)
> > + *anon_offset = cur_offset;
> > + goto out;
> > + }
> > + }
> > + }
> > + if (top > 0) {
> > + /* Pop from the anonymous stack and retry */
> > + tid = anon_stack[--top].tid;
> > + cur_offset = anon_stack[top].offset;
> > + type = btf_type_by_id(btf, tid);
> > + goto retry;
> > + }
> > + member = NULL;
> > +
> > +out:
> > + kfree(anon_stack);
> > + return member;
> > +}
> > +
> > #define BTF_SHOW_MAX_ITER 10
> >
> > #define BTF_KIND_BIT(kind) (1ULL << kind)
> > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> > index 057cd975d014..64b61f67a403 100644
> > --- a/kernel/trace/Makefile
> > +++ b/kernel/trace/Makefile
> > @@ -99,7 +99,6 @@ obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
> > endif
> > obj-$(CONFIG_DYNAMIC_EVENTS) += trace_dynevent.o
> > obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
> > -obj-$(CONFIG_PROBE_EVENTS_BTF_ARGS) += trace_btf.o
> > obj-$(CONFIG_UPROBE_EVENTS) += trace_uprobe.o
> > obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o
> > obj-$(CONFIG_FTRACE_RECORD_RECURSION) += trace_recursion_record.o
> > diff --git a/kernel/trace/trace_btf.c b/kernel/trace/trace_btf.c
> > deleted file mode 100644
> > index ca224d53bfdc..000000000000
> > --- a/kernel/trace/trace_btf.c
> > +++ /dev/null
> > @@ -1,122 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -#include <linux/btf.h>
> > -#include <linux/kernel.h>
> > -#include <linux/slab.h>
> > -
> > -#include "trace_btf.h"
> > -
> > -/*
> > - * Find a function proto type by name, and return the btf_type with its btf
> > - * in *@btf_p. Return NULL if not found.
> > - * Note that caller has to call btf_put(*@btf_p) after using the btf_type.
> > - */
> > -const struct btf_type *btf_find_func_proto(const char *func_name, struct btf **btf_p)
> > -{
> > - const struct btf_type *t;
> > - s32 id;
> > -
> > - id = bpf_find_btf_id(func_name, BTF_KIND_FUNC, btf_p);
> > - if (id < 0)
> > - return NULL;
> > -
> > - /* Get BTF_KIND_FUNC type */
> > - t = btf_type_by_id(*btf_p, id);
> > - if (!t || !btf_type_is_func(t))
> > - goto err;
> > -
> > - /* The type of BTF_KIND_FUNC is BTF_KIND_FUNC_PROTO */
> > - t = btf_type_by_id(*btf_p, t->type);
> > - if (!t || !btf_type_is_func_proto(t))
> > - goto err;
> > -
> > - return t;
> > -err:
> > - btf_put(*btf_p);
> > - return NULL;
> > -}
> > -
> > -/*
> > - * Get function parameter with the number of parameters.
> > - * This can return NULL if the function has no parameters.
> > - * It can return -EINVAL if the @func_proto is not a function proto type.
> > - */
> > -const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s32 *nr)
> > -{
> > - if (!btf_type_is_func_proto(func_proto))
> > - return ERR_PTR(-EINVAL);
> > -
> > - *nr = btf_type_vlen(func_proto);
> > - if (*nr > 0)
> > - return (const struct btf_param *)(func_proto + 1);
> > - else
> > - return NULL;
> > -}
> > -
> > -#define BTF_ANON_STACK_MAX 16
> > -
> > -struct btf_anon_stack {
> > - u32 tid;
> > - u32 offset;
> > -};
> > -
> > -/*
> > - * Find a member of data structure/union by name and return it.
> > - * Return NULL if not found, or -EINVAL if parameter is invalid.
> > - * If the member is an member of anonymous union/structure, the offset
> > - * of that anonymous union/structure is stored into @anon_offset. Caller
> > - * can calculate the correct offset from the root data structure by
> > - * adding anon_offset to the member's offset.
> > - */
> > -const struct btf_member *btf_find_struct_member(struct btf *btf,
> > - const struct btf_type *type,
> > - const char *member_name,
> > - u32 *anon_offset)
> > -{
> > - struct btf_anon_stack *anon_stack;
> > - const struct btf_member *member;
> > - u32 tid, cur_offset = 0;
> > - const char *name;
> > - int i, top = 0;
> > -
> > - anon_stack = kcalloc(BTF_ANON_STACK_MAX, sizeof(*anon_stack), GFP_KERNEL);
> > - if (!anon_stack)
> > - return ERR_PTR(-ENOMEM);
> > -
> > -retry:
> > - if (!btf_type_is_struct(type)) {
> > - member = ERR_PTR(-EINVAL);
> > - goto out;
> > - }
> > -
> > - for_each_member(i, type, member) {
> > - if (!member->name_off) {
> > - /* Anonymous union/struct: push it for later use */
> > - type = btf_type_skip_modifiers(btf, member->type, &tid);
> > - if (type && top < BTF_ANON_STACK_MAX) {
> > - anon_stack[top].tid = tid;
> > - anon_stack[top++].offset =
> > - cur_offset + member->offset;
> > - }
> > - } else {
> > - name = btf_name_by_offset(btf, member->name_off);
> > - if (name && !strcmp(member_name, name)) {
> > - if (anon_offset)
> > - *anon_offset = cur_offset;
> > - goto out;
> > - }
> > - }
> > - }
> > - if (top > 0) {
> > - /* Pop from the anonymous stack and retry */
> > - tid = anon_stack[--top].tid;
> > - cur_offset = anon_stack[top].offset;
> > - type = btf_type_by_id(btf, tid);
> > - goto retry;
> > - }
> > - member = NULL;
> > -
> > -out:
> > - kfree(anon_stack);
> > - return member;
> > -}
> > -
> > diff --git a/kernel/trace/trace_btf.h b/kernel/trace/trace_btf.h
> > deleted file mode 100644
> > index 4bc44bc261e6..000000000000
> > --- a/kernel/trace/trace_btf.h
> > +++ /dev/null
> > @@ -1,11 +0,0 @@
> > -/* SPDX-License-Identifier: GPL-2.0 */
> > -#include <linux/btf.h>
> > -
> > -const struct btf_type *btf_find_func_proto(const char *func_name,
> > - struct btf **btf_p);
> > -const struct btf_param *btf_get_func_param(const struct btf_type *func_proto,
> > - s32 *nr);
> > -const struct btf_member *btf_find_struct_member(struct btf *btf,
> > - const struct btf_type *type,
> > - const char *member_name,
> > - u32 *anon_offset);
> > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> > index 4dc74d73fc1d..b33c424b8ee0 100644
> > --- a/kernel/trace/trace_probe.c
> > +++ b/kernel/trace/trace_probe.c
> > @@ -12,7 +12,7 @@
> > #define pr_fmt(fmt) "trace_probe: " fmt
> >
> > #include <linux/bpf.h>
> > -#include "trace_btf.h"
> > +#include <linux/btf.h>
> >
> > #include "trace_probe.h"
> >
>
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
prev parent reply other threads:[~2026-07-15 1:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-10 13:54 [PATCH] bpf/btf: Move tracing BTF APIs to the BTF library Masami Hiramatsu (Google)
2023-10-10 14:54 ` Steven Rostedt
2023-10-11 16:19 ` Alan Maguire
2026-07-14 14:34 ` Steven Rostedt
2026-07-15 1:53 ` Masami Hiramatsu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260715105314.5708c8ab918718942fb5b31e@kernel.org \
--to=mhiramat@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=martin.lau@linux.dev \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox