Commit e6199511 authored by Kui-Feng Lee's avatar Kui-Feng Lee Committed by Martin KaFai Lau
Browse files

bpf: add struct_ops_tab to btf. 



Maintain a registry of registered struct_ops types in the per-btf (module)
struct_ops_tab. This registry allows for easy lookup of struct_ops types
that are registered by a specific module.

It is a preparation work for supporting kernel module struct_ops in a
latter patch. Each struct_ops will be registered under its own kernel
module btf and will be stored in the newly added btf->struct_ops_tab. The
bpf verifier and bpf syscall (e.g. prog and map cmd) can find the
struct_ops and its btf type/size/id... information from
btf->struct_ops_tab.

Signed-off-by: default avatarKui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-5-thinker.li@gmail.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 4c5763ed

kernel/bpf/btf.c

+55 −0
Original line number Diff line number Diff line
@@ -241,6 +241,12 @@ struct btf_id_dtor_kfunc_tab { 
	struct btf_id_dtor_kfunc dtors[];

};



struct btf_struct_ops_tab {

	u32 cnt;

	u32 capacity;

	struct bpf_struct_ops_desc ops[];

};



struct btf {

	void *data;

	struct btf_type **types;
@@ -258,6 +264,7 @@ struct btf { 
	struct btf_kfunc_set_tab *kfunc_set_tab;

	struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab;

	struct btf_struct_metas *struct_meta_tab;

	struct btf_struct_ops_tab *struct_ops_tab;



	/* split BTF support */

	struct btf *base_btf;
@@ -1688,11 +1695,20 @@ static void btf_free_struct_meta_tab(struct btf *btf) 
	btf->struct_meta_tab = NULL;

}



static void btf_free_struct_ops_tab(struct btf *btf)

{

	struct btf_struct_ops_tab *tab = btf->struct_ops_tab;



	kfree(tab);

	btf->struct_ops_tab = NULL;

}



static void btf_free(struct btf *btf)

{

	btf_free_struct_meta_tab(btf);

	btf_free_dtor_kfunc_tab(btf);

	btf_free_kfunc_set_tab(btf);

	btf_free_struct_ops_tab(btf);

	kvfree(btf->types);

	kvfree(btf->resolved_sizes);

	kvfree(btf->resolved_ids);
@@ -8689,3 +8705,42 @@ bool btf_type_ids_nocast_alias(struct bpf_verifier_log *log, 


	return !strncmp(reg_name, arg_name, cmp_len);

}



static int

btf_add_struct_ops(struct btf *btf, struct bpf_struct_ops *st_ops)

{

	struct btf_struct_ops_tab *tab, *new_tab;

	int i;



	tab = btf->struct_ops_tab;

	if (!tab) {

		tab = kzalloc(offsetof(struct btf_struct_ops_tab, ops[4]),

			      GFP_KERNEL);

		if (!tab)

			return -ENOMEM;

		tab->capacity = 4;

		btf->struct_ops_tab = tab;

	}



	for (i = 0; i < tab->cnt; i++)

		if (tab->ops[i].st_ops == st_ops)

			return -EEXIST;



	if (tab->cnt == tab->capacity) {

		new_tab = krealloc(tab,

				   offsetof(struct btf_struct_ops_tab,

					    ops[tab->capacity * 2]),

				   GFP_KERNEL);

		if (!new_tab)

			return -ENOMEM;

		tab = new_tab;

		tab->capacity *= 2;

		btf->struct_ops_tab = tab;

	}



	tab->ops[btf->struct_ops_tab->cnt].st_ops = st_ops;



	btf->struct_ops_tab->cnt++;



	return 0;

}