| Message ID | 20210915050943.679062-4-memxor@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [bpf-next,v3,01/10] bpf: Introduce BPF support for kernel module function calls | expand |
On Wed, Sep 15, 2021 at 11:06 AM Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote: > > On Wed, Sep 15, 2021 at 09:48:35PM IST, Alexei Starovoitov wrote: > > On Wed, Sep 15, 2021 at 10:39:36AM +0530, Kumar Kartikeya Dwivedi wrote: > > > This adds helpers for registering btf_id_set from modules and the > > > check_kfunc_call callback that can be used to look them up. > > > > > > With in kernel sets, the way this is supposed to work is, in kernel > > > callback looks up within the in-kernel kfunc whitelist, and then defers > > > to the dynamic BTF set lookup if it doesn't find the BTF id. If there is > > > no in-kernel BTF id set, this callback can be used directly. > > > > > > Also fix includes for btf.h and bpfptr.h so that they can included in > > > isolation. This is in preparation for their usage in tcp_bbr, tcp_cubic > > > and tcp_dctcp modules in the next patch. > > > > > > Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> > > > --- > > > include/linux/bpfptr.h | 1 + > > > include/linux/btf.h | 32 ++++++++++++++++++++++++++ > > > kernel/bpf/btf.c | 51 ++++++++++++++++++++++++++++++++++++++++++ > > > 3 files changed, 84 insertions(+) > > > > > > diff --git a/include/linux/bpfptr.h b/include/linux/bpfptr.h > > > index 546e27fc6d46..46e1757d06a3 100644 > > > --- a/include/linux/bpfptr.h > > > +++ b/include/linux/bpfptr.h > > > @@ -3,6 +3,7 @@ > > > #ifndef _LINUX_BPFPTR_H > > > #define _LINUX_BPFPTR_H > > > > > > +#include <linux/mm.h> > > > > Could you explain what this is for? > > > > When e.g. tcp_bbr.c includes btf.h and btf_ids.h without this, it leads to this > error. > > from net/ipv4/tcp_bbr.c:59: > ./include/linux/bpfptr.h: In function ‘kvmemdup_bpfptr’: > ./include/linux/bpfptr.h:67:19: error: implicit declaration of function ‘kvmalloc’; > did you mean ‘kmalloc’? [-Werror=implicit-function-declaration] > 67 | void *p = kvmalloc(len, GFP_USER | __GFP_NOWARN); > | ^~~~~~~~ > | kmalloc > ./include/linux/bpfptr.h:67:19: warning: initialization of ‘void *’ from ‘int’ > makes pointer from integer without a cast [-Wint-conversion] > ./include/linux/bpfptr.h:72:17: error: implicit declaration of function ‘kvfree’; > did you mean ‘kfree’? [-Werror=implicit-function-declaration] > 72 | kvfree(p); > | ^~~~~~ > | kfree Interesting. It's because of kvmalloc in kvmemdup_bpfptr. Which is used in ___bpf_copy_key. Which is used in map_update_elem. And afair all maps enforce key_size < KMALLOC_MAX_SIZE. Not sure why kvmalloc was there. If it was kmalloc instead then #include <linux/slab.h> in linux/sockptr.h that is included by linux/bpfptr.h would have been enough. A food for thought.
diff --git a/include/linux/bpfptr.h b/include/linux/bpfptr.h index 546e27fc6d46..46e1757d06a3 100644 --- a/include/linux/bpfptr.h +++ b/include/linux/bpfptr.h @@ -3,6 +3,7 @@ #ifndef _LINUX_BPFPTR_H #define _LINUX_BPFPTR_H +#include <linux/mm.h> #include <linux/sockptr.h> typedef sockptr_t bpfptr_t; diff --git a/include/linux/btf.h b/include/linux/btf.h index 214fde93214b..e29a486d09d4 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -5,8 +5,10 @@ #define _LINUX_BTF_H 1 #include <linux/types.h> +#include <linux/bpfptr.h> #include <uapi/linux/btf.h> #include <uapi/linux/bpf.h> +#include <linux/mutex.h> #define BTF_TYPE_EMIT(type) ((void)(type *)0) #define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val) @@ -238,4 +240,34 @@ static inline const char *btf_name_by_offset(const struct btf *btf, } #endif +struct kfunc_btf_id_set { + struct list_head list; + struct btf_id_set *set; + struct module *owner; +}; + +struct kfunc_btf_id_list; + +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES +void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l, + struct kfunc_btf_id_set *s); +void unregister_kfunc_btf_id_set(struct kfunc_btf_id_list *l, + struct kfunc_btf_id_set *s); +#else +static inline void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l, + struct kfunc_btf_id_set *s) +{ +} +static inline void unregister_kfunc_btf_id_set(struct kfunc_btf_id_list *l, + struct kfunc_btf_id_set *s) +{ +} +#endif + +#define DECLARE_CHECK_KFUNC_CALLBACK(type) \ + bool __bpf_check_##type##_kfunc_call(u32 kfunc_id, struct module *owner) +#define DEFINE_KFUNC_BTF_ID_SET(set, name) \ + struct kfunc_btf_id_set name = { LIST_HEAD_INIT(name.list), (set), \ + THIS_MODULE } + #endif diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index c3d605b22473..d17f45b163f5 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6343,3 +6343,54 @@ const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = { }; BTF_ID_LIST_GLOBAL_SINGLE(btf_task_struct_ids, struct, task_struct) + +struct kfunc_btf_id_list { + struct list_head list; + struct mutex mutex; +}; + +#ifdef CONFIG_DEBUG_INFO_BTF_MODULES + +void register_kfunc_btf_id_set(struct kfunc_btf_id_list *l, + struct kfunc_btf_id_set *s) +{ + mutex_lock(&l->mutex); + list_add(&s->list, &l->list); + mutex_unlock(&l->mutex); +} +EXPORT_SYMBOL_GPL(register_kfunc_btf_id_set); + +void unregister_kfunc_btf_id_set(struct kfunc_btf_id_list *l, + struct kfunc_btf_id_set *s) +{ + mutex_lock(&l->mutex); + list_del_init(&s->list); + mutex_unlock(&l->mutex); +} +EXPORT_SYMBOL_GPL(unregister_kfunc_btf_id_set); + +#endif + +#define DEFINE_KFUNC_BTF_ID_LIST(name) \ + struct kfunc_btf_id_list name = { LIST_HEAD_INIT(name.list), \ + __MUTEX_INITIALIZER(name.mutex) }; \ + EXPORT_SYMBOL_GPL(name) + +#define DEFINE_CHECK_KFUNC_CALLBACK(type, list_name) \ + bool __bpf_check_##type##_kfunc_call(u32 kfunc_id, \ + struct module *owner) \ + { \ + struct kfunc_btf_id_set *s; \ + if (!owner || !IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) \ + return false; \ + mutex_lock(&list_name.mutex); \ + list_for_each_entry(s, &list_name.list, list) { \ + if (s->owner == owner && \ + btf_id_set_contains(s->set, kfunc_id)) { \ + mutex_unlock(&list_name.mutex); \ + return true; \ + } \ + } \ + mutex_unlock(&list_name.mutex); \ + return false; \ + }
This adds helpers for registering btf_id_set from modules and the check_kfunc_call callback that can be used to look them up. With in kernel sets, the way this is supposed to work is, in kernel callback looks up within the in-kernel kfunc whitelist, and then defers to the dynamic BTF set lookup if it doesn't find the BTF id. If there is no in-kernel BTF id set, this callback can be used directly. Also fix includes for btf.h and bpfptr.h so that they can included in isolation. This is in preparation for their usage in tcp_bbr, tcp_cubic and tcp_dctcp modules in the next patch. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> --- include/linux/bpfptr.h | 1 + include/linux/btf.h | 32 ++++++++++++++++++++++++++ kernel/bpf/btf.c | 51 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 84 insertions(+)