// 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;}