123 lines
3.0 KiB
C
123 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/btf.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/slab.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;
|
|
}
|
|
|
|
#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 */
|
|
if (btf_type_skip_modifiers(btf, member->type, &tid) &&
|
|
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;
|
|
}
|
|
|