Commit ebeed8d4 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google)
Browse files

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: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent b1d1e904

kernel/trace/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

kernel/trace/trace_btf.c

0 → 100644
+53 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/btf.h>

#include <linux/kernel.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;

}

kernel/trace/trace_btf.h

0 → 100644
+7 −0
Original line number Diff line number Diff line 
/* 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);

kernel/trace/trace_probe.c

+11 −40
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#define pr_fmt(fmt)	"trace_probe: " fmt



#include <linux/bpf.h>

#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);