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bpf: add struct_ops_tab to btf.

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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: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-5-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Kui-Feng Lee 2024-01-19 14:49:55 -08:00 committed by Martin KaFai Lau
parent 4c5763ed99
commit e61995111a
1 changed files with 55 additions and 0 deletions
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55
kernel/bpf/btf.c
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@ -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;
}