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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) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu (Google) 2023-08-23 01:25:52 +09:00
parent b1d1e90490
commit ebeed8d4a5
4 changed files with 72 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
kernel/trace/Makefile
View File

@ -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

53
kernel/trace/trace_btf.c Normal file
View File

@ -0,0 +1,53 @@
// 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;
}

7
kernel/trace/trace_btf.h Normal file
View File

@ -0,0 +1,7 @@
/* 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);

51
kernel/trace/trace_probe.c
View File

@ -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);