On Fri, Dec 07, 2018 at 07:37:35PM -0800, Yonghong Song wrote:
>
>
> On 12/7/18 4:53 PM, Roman Gushchin wrote:
> > Implement bpffs pretty printing for cgroup local storage maps
> > (both shared and per-cpu).
> > Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):
> >
> > Shared:
> > $ cat /sys/fs/bpf/map_2
> > # WARNING!! The output is for debug purpose only
> > # WARNING!! The output format will change
> > {4294968594,1}: {9999,1039896}
> >
> > Per-cpu:
> > $ cat /sys/fs/bpf/map_1
> > # WARNING!! The output is for debug purpose only
> > # WARNING!! The output format will change
> > {4294968594,1}: {
> > cpu0: {0,0,0,0,0}
> > cpu1: {0,0,0,0,0}
> > cpu2: {1,104,0,0,0}
> > cpu3: {0,0,0,0,0}
> > }
> >
> > Signed-off-by: Roman Gushchin <g...@fb.com>
> > Cc: Alexei Starovoitov <a...@kernel.org>
> > Cc: Daniel Borkmann <dan...@iogearbox.net>
> > ---
> > include/linux/btf.h | 10 +++++
> > kernel/bpf/local_storage.c | 90 +++++++++++++++++++++++++++++++++++++-
> > 2 files changed, 99 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/btf.h b/include/linux/btf.h
> > index 8c2199b5d250..ac67bc4cbfd9 100644
> > --- a/include/linux/btf.h
> > +++ b/include/linux/btf.h
> > @@ -5,6 +5,7 @@
> > #define _LINUX_BTF_H 1
> >
> > #include <linux/types.h>
> > +#include <uapi/linux/btf.h>
> >
> > struct btf;
> > struct btf_type;
> > @@ -63,4 +64,13 @@ static inline const char *btf_name_by_offset(const
> > struct btf *btf,
> > }
> > #endif
> >
> > +static inline const struct btf_type *btf_orig_type(const struct btf *btf,
> > + const struct btf_type *t)
> > +{
> > + while (t && BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF)
> > + t = btf_type_by_id(btf, t->type);
> technically, type modifier "const" and "volatile" can apply to member
> type as well. But these modifiers really don't make sense here.
> Could you add a comment here to mention that they will be treated
> as an error since such a programming is not really recommended?
Switched over to btf_type_id_size() based on Martin's suggestion.
>
> > +
> > + return t;
> > +}
> > +
> > #endif
> > diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> > index b65017dead44..7b51fe1aba3c 100644
> > --- a/kernel/bpf/local_storage.c
> > +++ b/kernel/bpf/local_storage.c
> > @@ -1,11 +1,13 @@
> > //SPDX-License-Identifier: GPL-2.0
> > #include <linux/bpf-cgroup.h>
> > #include <linux/bpf.h>
> > +#include <linux/btf.h>
> > #include <linux/bug.h>
> > #include <linux/filter.h>
> > #include <linux/mm.h>
> > #include <linux/rbtree.h>
> > #include <linux/slab.h>
> > +#include <uapi/linux/btf.h>
> >
> > DEFINE_PER_CPU(struct bpf_cgroup_storage*,
> > bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
> >
> > @@ -308,6 +310,91 @@ static int cgroup_storage_delete_elem(struct bpf_map
> > *map, void *key)
> > return -EINVAL;
> > }
> >
> > +static int cgroup_storage_check_btf(const struct bpf_map *map,
> > + const struct btf *btf,
> > + const struct btf_type *key_type,
> > + const struct btf_type *value_type)
> > +{
> > + const struct btf_type *st, *t;
> > + struct btf_member *m;
> > +
> > + /* Key is expected to be of struct bpf_cgroup_storage_key type,
> > + * which is:
> > + * struct bpf_cgroup_storage_key {
> > + * __u64 cgroup_inode_id;
> > + * __u32 attach_type;
> > + * };
> > + */
> > +
> > + /*
> > + * Key_type must be a structure (or a typedef of a structure) with
> > + * two members.
> > + */
> > + st = btf_orig_type(btf, key_type);
> > + if (BTF_INFO_KIND(st->info) != BTF_KIND_STRUCT ||
> > + BTF_INFO_VLEN(st->info) != 2)
> > + return -EINVAL;
> > +
> > + /*
> > + * The first field must be a 64 bit integer at 0 offset.
> > + */
> > + m = (struct btf_member *)(st + 1);
> > + t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> > + if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT || m->offset ||
> > + t->size !=
> > + FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id))
> > + return -EINVAL;
>
> We should not use t->size here. The "t->size" is the type size, and the
> real number of bits held by the member is BTF_INT_BITS(...) with the
> argument of the u32 int value after "t".
>
> > +
> > + /*
> > + * The second field must be a 32 bit integer at 0 offset.
> > + */
> > + m = m + 1;
> > + t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> > + if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT ||
> > + m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
> > + BITS_PER_BYTE || t->size !=
> > + FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type))
> > + return -EINVAL;
>
> The same is here. t->size should not be used.
> BTF_INT_BITS(...) should be used.
Fixed in v2, which I'll send soon.
Thank you for the review!
