| Message ID | 168960742712.34107.9849785489776347376.stgit@devnote2 (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | tracing: Improbe BTF support on probe events | expand |
On 17/07/2023 16:23, Masami Hiramatsu (Google) wrote: > From: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Add btf_find_struct_member() API to search a member of a given data structure > or union from the member's name. > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> A few small things below, but Reviewed-by: Alan Maguire <alan.maguire@oracle.com> > --- > include/linux/btf.h | 3 +++ > kernel/bpf/btf.c | 38 ++++++++++++++++++++++++++++++++++++++ > 2 files changed, 41 insertions(+) > > diff --git a/include/linux/btf.h b/include/linux/btf.h > index 98fbbcdd72ec..097fe9b51562 100644 > --- a/include/linux/btf.h > +++ b/include/linux/btf.h > @@ -225,6 +225,9 @@ const struct btf_type *btf_find_func_proto(struct btf *btf, > const char *func_name); > const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, > s32 *nr); > +const struct btf_member *btf_find_struct_member(struct btf *btf, > + const struct btf_type *type, > + const char *member_name); > > #define for_each_member(i, struct_type, member) \ > for (i = 0, member = btf_type_member(struct_type); \ > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index e015b52956cb..452ffb0393d6 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -1992,6 +1992,44 @@ const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s3 > return NULL; > } > > +/* > + * Find a member of data structure/union by name and return it. > + * Return NULL if not found, or -EINVAL if parameter is invalid. > + */ > +const struct btf_member *btf_find_struct_member(struct btf *btf, > + const struct btf_type *type, > + const char *member_name) > +{ > + const struct btf_member *members, *ret; > + const char *name; > + int i, vlen; > + > + if (!btf || !member_name || !btf_type_is_struct(type)) > + return ERR_PTR(-EINVAL); > + > + vlen = btf_type_vlen(type); > + members = (const struct btf_member *)(type + 1); > + > + for (i = 0; i < vlen; i++) { could use for_each_member() here I think, or perhaps use btf_type_member(type) when getting member pointer above. > + if (!members[i].name_off) { > + /* unnamed union: dig deeper */ > + type = btf_type_by_id(btf, members[i].type); > + if (!IS_ERR_OR_NULL(type)) { > + ret = btf_find_struct_member(btf, type, > + member_name); You'll need to skip modifiers before calling btf_find_struct_member() here I think; it's possible to have a const anonymous union for example, so to get to the union you'd need to skip the modifiers first. Otherwise you could fail the btf_type_is_struct() test on re-entry. > + if (!IS_ERR_OR_NULL(ret)) > + return ret; > + } > + } else { > + name = btf_name_by_offset(btf, members[i].name_off); > + if (name && !strcmp(member_name, name)) > + return &members[i]; > + } > + } > + > + return NULL; > +} > + > static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id) > { > while (type_id < btf->start_id) > >
On Thu, 20 Jul 2023 23:34:42 +0100 Alan Maguire <alan.maguire@oracle.com> wrote: > On 17/07/2023 16:23, Masami Hiramatsu (Google) wrote: > > From: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > > > Add btf_find_struct_member() API to search a member of a given data structure > > or union from the member's name. > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > A few small things below, but > > Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Thanks > > > --- > > include/linux/btf.h | 3 +++ > > kernel/bpf/btf.c | 38 ++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 41 insertions(+) > > > > diff --git a/include/linux/btf.h b/include/linux/btf.h > > index 98fbbcdd72ec..097fe9b51562 100644 > > --- a/include/linux/btf.h > > +++ b/include/linux/btf.h > > @@ -225,6 +225,9 @@ const struct btf_type *btf_find_func_proto(struct btf *btf, > > const char *func_name); > > const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, > > s32 *nr); > > +const struct btf_member *btf_find_struct_member(struct btf *btf, > > + const struct btf_type *type, > > + const char *member_name); > > > > #define for_each_member(i, struct_type, member) \ > > for (i = 0, member = btf_type_member(struct_type); \ > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > > index e015b52956cb..452ffb0393d6 100644 > > --- a/kernel/bpf/btf.c > > +++ b/kernel/bpf/btf.c > > @@ -1992,6 +1992,44 @@ const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s3 > > return NULL; > > } > > > > +/* > > + * Find a member of data structure/union by name and return it. > > + * Return NULL if not found, or -EINVAL if parameter is invalid. > > + */ > > +const struct btf_member *btf_find_struct_member(struct btf *btf, > > + const struct btf_type *type, > > + const char *member_name) > > +{ > > + const struct btf_member *members, *ret; > > + const char *name; > > + int i, vlen; > > + > > + if (!btf || !member_name || !btf_type_is_struct(type)) > > + return ERR_PTR(-EINVAL); > > + > > + vlen = btf_type_vlen(type); > > + members = (const struct btf_member *)(type + 1); > > + > > + for (i = 0; i < vlen; i++) { > > could use for_each_member() here I think, or perhaps use > btf_type_member(type) when getting member pointer above. Thanks! I missed that macro. > > > + if (!members[i].name_off) { > > + /* unnamed union: dig deeper */ > > + type = btf_type_by_id(btf, members[i].type); > > + if (!IS_ERR_OR_NULL(type)) { > > + ret = btf_find_struct_member(btf, type, > > + member_name); > > You'll need to skip modifiers before calling btf_find_struct_member() > here I think; it's possible to have a const anonymous union for example, Yeah, it is possible. Let me add it. > so to get to the union you'd need to skip the modifiers first. Otherwise > you could fail the btf_type_is_struct() test on re-entry. Indeed. Thank you! > > > > + if (!IS_ERR_OR_NULL(ret)) > > + return ret; > > + } > > + } else { > > + name = btf_name_by_offset(btf, members[i].name_off); > > + if (name && !strcmp(member_name, name)) > > + return &members[i]; > > + } > > + } > > + > > + return NULL; > > +} > > + > > static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id) > > { > > while (type_id < btf->start_id) > > > >
diff --git a/include/linux/btf.h b/include/linux/btf.h index 98fbbcdd72ec..097fe9b51562 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -225,6 +225,9 @@ const struct btf_type *btf_find_func_proto(struct btf *btf, const char *func_name); const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s32 *nr); +const struct btf_member *btf_find_struct_member(struct btf *btf, + const struct btf_type *type, + const char *member_name); #define for_each_member(i, struct_type, member) \ for (i = 0, member = btf_type_member(struct_type); \ diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index e015b52956cb..452ffb0393d6 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -1992,6 +1992,44 @@ const struct btf_param *btf_get_func_param(const struct btf_type *func_proto, s3 return NULL; } +/* + * Find a member of data structure/union by name and return it. + * Return NULL if not found, or -EINVAL if parameter is invalid. + */ +const struct btf_member *btf_find_struct_member(struct btf *btf, + const struct btf_type *type, + const char *member_name) +{ + const struct btf_member *members, *ret; + const char *name; + int i, vlen; + + if (!btf || !member_name || !btf_type_is_struct(type)) + return ERR_PTR(-EINVAL); + + vlen = btf_type_vlen(type); + members = (const struct btf_member *)(type + 1); + + for (i = 0; i < vlen; i++) { + if (!members[i].name_off) { + /* unnamed union: dig deeper */ + type = btf_type_by_id(btf, members[i].type); + if (!IS_ERR_OR_NULL(type)) { + ret = btf_find_struct_member(btf, type, + member_name); + if (!IS_ERR_OR_NULL(ret)) + return ret; + } + } else { + name = btf_name_by_offset(btf, members[i].name_off); + if (name && !strcmp(member_name, name)) + return &members[i]; + } + } + + return NULL; +} + static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id) { while (type_id < btf->start_id)