From ebeed8d4a55513116116993861c98a72915265ba Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Wed, 23 Aug 2023 01:25:52 +0900 Subject: [PATCH] tracing/probes: Move finding func-proto API and getting func-param API to trace_btf 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. Link: https://lore.kernel.org/all/169272155255.160970.719426926348706349.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) Acked-by: Steven Rostedt (Google) --- kernel/trace/Makefile | 1 + kernel/trace/trace_btf.c | 53 ++++++++++++++++++++++++++++++++++++++ kernel/trace/trace_btf.h | 7 +++++ kernel/trace/trace_probe.c | 51 ++++++++---------------------------- 4 files changed, 72 insertions(+), 40 deletions(-) create mode 100644 kernel/trace/trace_btf.c create mode 100644 kernel/trace/trace_btf.h diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 64b61f67a403..057cd975d014 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -99,6 +99,7 @@ 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 new file mode 100644 index 000000000000..d70b8ee9af37 --- /dev/null +++ b/kernel/trace/trace_btf.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: GPL-2.0 +#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; +} + diff --git a/kernel/trace/trace_btf.h b/kernel/trace/trace_btf.h new file mode 100644 index 000000000000..98685e9a556c --- /dev/null +++ b/kernel/trace/trace_btf.h @@ -0,0 +1,7 @@ +/* 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); diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index ecbe28f8d676..c3ac5698e80b 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -12,6 +12,7 @@ #define pr_fmt(fmt) "trace_probe: " fmt #include +#include "trace_btf.h" #include "trace_probe.h" @@ -361,38 +362,6 @@ 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_p) -{ - const struct btf_type *t; - struct btf *btf = NULL; - s32 id; - - if (!funcname) - return ERR_PTR(-EINVAL); - - id = bpf_find_btf_id(funcname, BTF_KIND_FUNC, &btf); - 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)) - goto err; - - /* 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)) - goto err; - - *btf_p = btf; - return t; - -err: - btf_put(btf); - return ERR_PTR(-ENOENT); -} - static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr, struct btf **btf_p, bool tracepoint) { @@ -403,12 +372,13 @@ static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr if (!funcname || !nr) return ERR_PTR(-EINVAL); - t = find_btf_func_proto(funcname, &btf); - if (IS_ERR(t)) + t = btf_find_func_proto(funcname, &btf); + if (!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)) + goto err; /* Hide the first 'data' argument of tracepoint */ if (tracepoint) { @@ -421,6 +391,7 @@ static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr return param; } +err: btf_put(btf); return NULL; } @@ -496,8 +467,8 @@ static const struct fetch_type *parse_btf_retval_type( if (ctx->funcname) { /* Do not use ctx->btf, because it must be used with ctx->param */ - t = find_btf_func_proto(ctx->funcname, &btf); - if (!IS_ERR(t)) { + t = btf_find_func_proto(ctx->funcname, &btf); + if (t) { typestr = type_from_btf_id(btf, t->type); btf_put(btf); } @@ -512,8 +483,8 @@ static bool is_btf_retval_void(const char *funcname) struct btf *btf; bool ret; - t = find_btf_func_proto(funcname, &btf); - if (IS_ERR(t)) + t = btf_find_func_proto(funcname, &btf); + if (!t) return false; ret = (t->type == 0);