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Message-Id: <168960741686.34107.6330273416064011062.stgit@devnote2>
Date: Tue, 18 Jul 2023 00:23:37 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: linux-trace-kernel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
mhiramat@...nel.org, Martin KaFai Lau <martin.lau@...ux.dev>,
bpf@...r.kernel.org, Sven Schnelle <svens@...ux.ibm.com>,
Alexei Starovoitov <ast@...nel.org>
Subject: [PATCH v2 2/9] bpf/btf: tracing: Move finding func-proto API and getting func-param API to BTF
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Move generic function-proto find API and getting function parameter API
to BTF library code from trace_probe.c. This will avoid redundant efforts
on different feature.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
include/linux/btf.h | 4 ++++
kernel/bpf/btf.c | 45 ++++++++++++++++++++++++++++++++++++++++
kernel/trace/trace_probe.c | 50 +++++++++++++-------------------------------
3 files changed, 64 insertions(+), 35 deletions(-)
diff --git a/include/linux/btf.h b/include/linux/btf.h
index cac9f304e27a..98fbbcdd72ec 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -221,6 +221,10 @@ const struct btf_type *
btf_resolve_size(const struct btf *btf, const struct btf_type *type,
u32 *type_size);
const char *btf_type_str(const struct btf_type *t);
+const struct btf_type *btf_find_func_proto(struct btf *btf,
+ const char *func_name);
+const struct btf_param *btf_get_func_param(const struct btf_type *func_proto,
+ s32 *nr);
#define for_each_member(i, struct_type, member) \
for (i = 0, member = btf_type_member(struct_type); \
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 817204d53372..e015b52956cb 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1947,6 +1947,51 @@ btf_resolve_size(const struct btf *btf, const struct btf_type *type,
return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
}
+/*
+ * Find a functio proto type by name, and return it.
+ * Return NULL if not found, or return -EINVAL if parameter is invalid.
+ */
+const struct btf_type *btf_find_func_proto(struct btf *btf, const char *func_name)
+{
+ const struct btf_type *t;
+ s32 id;
+
+ if (!btf || !func_name)
+ return ERR_PTR(-EINVAL);
+
+ id = btf_find_by_name_kind(btf, func_name, BTF_KIND_FUNC);
+ if (id <= 0)
+ return NULL;
+
+ /* Get BTF_KIND_FUNC type */
+ t = btf_type_by_id(btf, id);
+ if (!t || !btf_type_is_func(t))
+ return NULL;
+
+ /* The type of BTF_KIND_FUNC is BTF_KIND_FUNC_PROTO */
+ t = btf_type_by_id(btf, t->type);
+ if (!t || !btf_type_is_func_proto(t))
+ return NULL;
+
+ return t;
+}
+
+/*
+ * Get function parameter with the number of parameters.
+ * This can return NULL if the function has no parameters.
+ */
+const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s32 *nr)
+{
+ if (!func_proto || !nr)
+ return ERR_PTR(-EINVAL);
+
+ *nr = btf_type_vlen(func_proto);
+ if (*nr > 0)
+ return (const struct btf_param *)(func_proto + 1);
+ else
+ return NULL;
+}
+
static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index c68a72707852..cd89fc1ebb42 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -371,47 +371,23 @@ static const char *type_from_btf_id(struct btf *btf, s32 id)
return NULL;
}
-static const struct btf_type *find_btf_func_proto(const char *funcname)
-{
- struct btf *btf = traceprobe_get_btf();
- const struct btf_type *t;
- s32 id;
-
- if (!btf || !funcname)
- return ERR_PTR(-EINVAL);
-
- id = btf_find_by_name_kind(btf, funcname, BTF_KIND_FUNC);
- if (id <= 0)
- return ERR_PTR(-ENOENT);
-
- /* Get BTF_KIND_FUNC type */
- t = btf_type_by_id(btf, id);
- if (!t || !btf_type_is_func(t))
- return ERR_PTR(-ENOENT);
-
- /* The type of BTF_KIND_FUNC is BTF_KIND_FUNC_PROTO */
- t = btf_type_by_id(btf, t->type);
- if (!t || !btf_type_is_func_proto(t))
- return ERR_PTR(-ENOENT);
-
- return t;
-}
-
static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr,
bool tracepoint)
{
+ struct btf *btf = traceprobe_get_btf();
const struct btf_param *param;
const struct btf_type *t;
- if (!funcname || !nr)
+ if (!funcname || !nr || !btf)
return ERR_PTR(-EINVAL);
- t = find_btf_func_proto(funcname);
- if (IS_ERR(t))
+ t = btf_find_func_proto(btf, funcname);
+ if (IS_ERR_OR_NULL(t))
return (const struct btf_param *)t;
- *nr = btf_type_vlen(t);
- param = (const struct btf_param *)(t + 1);
+ param = btf_get_func_param(t, nr);
+ if (IS_ERR_OR_NULL(param))
+ return param;
/* Hide the first 'data' argument of tracepoint */
if (tracepoint) {
@@ -490,8 +466,8 @@ static const struct fetch_type *parse_btf_retval_type(
const struct btf_type *t;
if (btf && ctx->funcname) {
- t = find_btf_func_proto(ctx->funcname);
- if (!IS_ERR(t))
+ t = btf_find_func_proto(btf, ctx->funcname);
+ if (!IS_ERR_OR_NULL(t))
typestr = type_from_btf_id(btf, t->type);
}
@@ -500,10 +476,14 @@ static const struct fetch_type *parse_btf_retval_type(
static bool is_btf_retval_void(const char *funcname)
{
+ struct btf *btf = traceprobe_get_btf();
const struct btf_type *t;
- t = find_btf_func_proto(funcname);
- if (IS_ERR(t))
+ if (!btf)
+ return false;
+
+ t = btf_find_func_proto(btf, funcname);
+ if (IS_ERR_OR_NULL(t))
return false;
return t->type == 0;
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