From: Steven Rostedt <rostedt@goodmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@kernel.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: Tue, 14 Jul 2026 10:34:01 -0400 [thread overview]
Message-ID: <20260714103401.0aa3f9e0@gandalf.local.home> (raw)
In-Reply-To: <169694605862.516358.5321950027838863987.stgit@devnote2>
Whatever happened to this patch?
-- 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"
>
next prev parent reply other threads:[~2026-07-14 14:34 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 [this message]
2026-07-15 1:53 ` Masami Hiramatsu
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