Messages in this thread | | | Date | Wed, 20 Jun 2018 23:48:50 +0100 | From | Okash Khawaja <> | Subject | Re: [PATCH bpf-next 1/3] bpf: btf: export btf types and name by offset from lib |
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On Wed, Jun 20, 2018 at 11:40:19PM +0100, Song Liu wrote: > > > > On Jun 20, 2018, at 1:30 PM, Okash Khawaja <osk@fb.com> wrote: > > > > This patch introduces btf__resolve_type() function and exports two > > existing functions from libbpf. btf__resolve_type follows modifier > > types like const and typedef until it hits a type which actually takes > > up memory, and then returns it. This function follows similar pattern > > to btf__resolve_size but instead of computing size, it just returns > > the type. > > > > These functions will be used in the followig patch which parses > > information inside array of `struct btf_type *`. btf_name_by_offset is > > used for printing variable names. > > > > Signed-off-by: Okash Khawaja <osk@fb.com> > > Acked-by: Martin KaFai Lau <kafai@fb.com> > > > > --- > > tools/lib/bpf/btf.c | 65 ++++++++++++++++++++++++++++++++++++---------------- > > tools/lib/bpf/btf.h | 3 ++ > > 2 files changed, 48 insertions(+), 20 deletions(-) > > > > --- a/tools/lib/bpf/btf.c > > +++ b/tools/lib/bpf/btf.c > > @@ -17,6 +17,11 @@ > > > > #define BTF_MAX_NR_TYPES 65535 > > > > +#define IS_MODIFIER(k) (((k) == BTF_KIND_TYPEDEF) || \ > > + ((k) == BTF_KIND_VOLATILE) || \ > > + ((k) == BTF_KIND_CONST) || \ > > + ((k) == BTF_KIND_RESTRICT)) > > + > > static struct btf_type btf_void; > > > > struct btf { > > @@ -33,14 +38,6 @@ struct btf { > > int fd; > > }; > > > > -static const char *btf_name_by_offset(const struct btf *btf, uint32_t offset) > > -{ > > - if (offset < btf->hdr->str_len) > > - return &btf->strings[offset]; > > - else > > - return NULL; > > -} > > - > > static int btf_add_type(struct btf *btf, struct btf_type *t) > > { > > if (btf->types_size - btf->nr_types < 2) { > > @@ -190,15 +187,6 @@ static int btf_parse_type_sec(struct btf > > return 0; > > } > > > > -static const struct btf_type *btf_type_by_id(const struct btf *btf, > > - uint32_t type_id) > > -{ > > - if (type_id > btf->nr_types) > > - return NULL; > > - > > - return btf->types[type_id]; > > -} > > nit: Why do we need to move these two functions to later of the file? No real reason. It looked like this file was following a convention of keeping statics together. I'll put them back in place if no one objects.
> > Other than this, > > Acked-by: Song Liu <songliubraving@fb.com> Thanks
> > > - > > static bool btf_type_is_void(const struct btf_type *t) > > { > > return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD; > > @@ -234,7 +222,7 @@ int64_t btf__resolve_size(const struct b > > int64_t size = -1; > > int i; > > > > - t = btf_type_by_id(btf, type_id); > > + t = btf__type_by_id(btf, type_id); > > for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); > > i++) { > > size = btf_type_size(t); > > @@ -259,7 +247,7 @@ int64_t btf__resolve_size(const struct b > > return -EINVAL; > > } > > > > - t = btf_type_by_id(btf, type_id); > > + t = btf__type_by_id(btf, type_id); > > } > > > > if (size < 0) > > @@ -271,6 +259,26 @@ int64_t btf__resolve_size(const struct b > > return nelems * size; > > } > > > > +int32_t btf__resolve_type(const struct btf *btf, uint32_t type_id) > > +{ > > + const struct btf_type *t; > > + int depth = 0; > > + > > + t = btf__type_by_id(btf, type_id); > > + while (depth < MAX_RESOLVE_DEPTH && > > + !btf_type_is_void_or_null(t) && > > + IS_MODIFIER(BTF_INFO_KIND(t->info))) { > > + type_id = t->type; > > + t = btf__type_by_id(btf, type_id); > > + depth++; > > + } > > + > > + if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t)) > > + return -EINVAL; > > + > > + return type_id; > > +} > > + > > int32_t btf__find_by_name(const struct btf *btf, const char *type_name) > > { > > uint32_t i; > > @@ -280,7 +288,7 @@ int32_t btf__find_by_name(const struct b > > > > for (i = 1; i <= btf->nr_types; i++) { > > const struct btf_type *t = btf->types[i]; > > - const char *name = btf_name_by_offset(btf, t->name_off); > > + const char *name = btf__name_by_offset(btf, t->name_off); > > > > if (name && !strcmp(type_name, name)) > > return i; > > @@ -371,3 +379,20 @@ int btf__fd(const struct btf *btf) > > { > > return btf->fd; > > } > > + > > +const char *btf__name_by_offset(const struct btf *btf, uint32_t offset) > > +{ > > + if (offset < btf->hdr->str_len) > > + return &btf->strings[offset]; > > + else > > + return NULL; > > +} > > + > > +const struct btf_type *btf__type_by_id(const struct btf *btf, > > + uint32_t type_id) > > +{ > > + if (type_id > btf->nr_types) > > + return NULL; > > + > > + return btf->types[type_id]; > > +} > > --- a/tools/lib/bpf/btf.h > > +++ b/tools/lib/bpf/btf.h > > @@ -17,6 +17,9 @@ void btf__free(struct btf *btf); > > struct btf *btf__new(uint8_t *data, uint32_t size, btf_print_fn_t err_log); > > int32_t btf__find_by_name(const struct btf *btf, const char *type_name); > > int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id); > > +int32_t btf__resolve_type(const struct btf *btf, uint32_t type_id); > > int btf__fd(const struct btf *btf); > > +const char *btf__name_by_offset(const struct btf *btf, uint32_t offset); > > +const struct btf_type *btf__type_by_id(const struct btf *btf, uint32_t type_id); > > > > #endif > > >
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