From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52B4486341; Wed, 15 Jul 2026 01:53:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784080400; cv=none; b=H1hXqG+e1KWhtCXmWGqRHcHcdlT5+5NcbTf7+ErIOc2t3G6yPwVNhg7khOxmfXZHRL1GpBaU4HRj0bZtXFGYa+15S8hP4XQMwfww1yvTS9iDM/df1SC/NW7iI4EhDQgR2y8OxpyNM5UysgK4Jp7DLG11KcHweI0MVZUxvEhgerI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784080400; c=relaxed/simple; bh=PhcNvwSnjvy/2Zo2A00mnn0LBTk6NQqbMFVyrDmDk2k=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=pUSn3Vm3DBDvRFv1M+FCiSWkP0B2QPhyfuBGM8EPu0+LZJVocsofpXo1HYRkw+Dgq9X1/wvd4bdyY7K4jSOZEa2XZzN113+oQDS+XhKXWkeuYKRJ/X+eNtvwap5cvWdUatfsfNqW+R6GuS9NzO3E6vOi8WCeK0nqCBm50JYvUKE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nd9Z1dgO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nd9Z1dgO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 798BA1F000E9; Wed, 15 Jul 2026 01:53:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784080399; bh=UXBW/juAIMWcu3PBqtxPKmUX6J4RCuOVZU0N0+X4O7w=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=nd9Z1dgOG2tlkg9rPblaXC4y86/CW1Wvrr0GPBXeepYoY/mePFeTnd6XD3+dP4+lq UFBPU25TjUgMnLCH+5+mDRvPIWXXmlv2tz+LHV4Yd6mdVZZgdXjY3JltowTmWsTh7P SBntaUJxECYk8uYABVmXD93mvp95AAhp/A7BmASPTM7x+LziSDE6aPmfEj+vPuNp4k thk7WOrBxyoFg91vLs01+1ObMghCb3ZttgM+L17zc/sAmFyLJoEHg3v99J69P2wXai HmgxAe3UWivKgmulfxahUIIB03D7zGsLVcG4k5FVbJFvtXpqvBkaVEJ0kVlKPd4YMj FnTarVnRo2DFg== Date: Wed, 15 Jul 2026 10:53:14 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Martin KaFai Lau , Alexei Starovoitov , 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 Message-Id: <20260715105314.5708c8ab918718942fb5b31e@kernel.org> In-Reply-To: <20260714103401.0aa3f9e0@gandalf.local.home> References: <169694605862.516358.5321950027838863987.stgit@devnote2> <20260714103401.0aa3f9e0@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 14 Jul 2026 10:34:01 -0400 Steven Rostedt 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)" wrote: > > > From: Masami Hiramatsu (Google) > > > > 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) > > --- > > 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 > > -#include > > -#include > > - > > -#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 > > - > > -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 > > -#include "trace_btf.h" > > +#include > > > > #include "trace_probe.h" > > > > -- Masami Hiramatsu (Google)