On Tue, Jul 28, 2020 at 12:39:06PM -0700, Andrii Nakryiko wrote:
SNIP
>
> [...]
>
> > +#define BTF_SET_START(name) \
> > +__BTF_ID_LIST(name, local) \
> > +asm( \
> > +".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
> > +".local __BTF_ID__set__" #name "; \n" \
> > +"__BTF_ID__set__" #name ":; \n" \
> > +".zero 4 \n" \
> > +".popsection; \n");
> > +
> > +#define BTF_SET_END(name) \
> > +asm( \
> > +".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
> > +".size __BTF_ID__set__" #name ", .-" #name " \n" \
> > +".popsection; \n"); \
> > +extern struct btf_id_set name;
> > +
> > #else
>
> This local symbol assumption will probably at some point bite us.
> Yonghong already did global vs static variants for BTF ID list, we'll
> end up doing something like that for sets of BTF IDs as well. Let's do
> this similarly from the get go.
sure, will add that
>
> >
> > #define BTF_ID_LIST(name) static u32 name[5];
> > #define BTF_ID(prefix, name)
> > #define BTF_ID_UNUSED
> > #define BTF_ID_LIST_GLOBAL(name) u32 name[1];
> > +#define BTF_SET_START(name) static struct btf_id_set name = { 0 };
>
> nit: this zero is unnecessary and misleading (it's initialized for
> only the first member of a struct). Just {} is enough.
ok
>
> > +#define BTF_SET_END(name)
> >
> > #endif /* CONFIG_DEBUG_INFO_BTF */
> >
> > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > index 562d4453fad3..06714cdda0a9 100644
> > --- a/kernel/bpf/btf.c
> > +++ b/kernel/bpf/btf.c
> > @@ -21,6 +21,8 @@
> > #include <linux/btf_ids.h>
> > #include <linux/skmsg.h>
> > #include <linux/perf_event.h>
> > +#include <linux/bsearch.h>
> > +#include <linux/btf_ids.h>
> > #include <net/sock.h>
> >
> > /* BTF (BPF Type Format) is the meta data format which describes
> > @@ -4740,3 +4742,15 @@ u32 btf_id(const struct btf *btf)
> > {
> > return btf->id;
> > }
> > +
> > +static int btf_id_cmp_func(const void *a, const void *b)
> > +{
> > + const int *pa = a, *pb = b;
> > +
> > + return *pa - *pb;
> > +}
> > +
> > +bool btf_id_set_contains(struct btf_id_set *set, u32 id)
> > +{
> > + return bsearch(&id, set->ids, set->cnt, sizeof(int), btf_id_cmp_func) != NULL;
>
> very nit ;) sizeof(__u32)
sure ;-)
thanks,
jirka
