| Message ID | 20200625221304.2817194-4-jolsa@kernel.org |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: Add d_path helper | expand |
On Thu, Jun 25, 2020 at 3:13 PM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding support to generate .BTF_ids section that will hold BTF > ID lists for verifier. > > Adding macros that will help to define lists of BTF ID values > placed in .BTF_ids section. They are initially filled with zeros > (during compilation) and resolved later during the linking phase > by resolve_btfids tool. > > Following defines list of one BTF ID value: > > BTF_ID_LIST(bpf_skb_output_btf_ids) > BTF_ID(struct, sk_buff) > > It also defines following variable to access the list: > > extern int bpf_skb_output_btf_ids[]; > > Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- Looks good, with few nits below. Acked-by: Andrii Nakryiko <andriin@fb.com> > include/asm-generic/vmlinux.lds.h | 4 ++ > include/linux/btf_ids.h | 69 +++++++++++++++++++++++++++++++ > 2 files changed, 73 insertions(+) > create mode 100644 include/linux/btf_ids.h > [...] > diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h > new file mode 100644 > index 000000000000..f7f9dc4d9a9f > --- /dev/null > +++ b/include/linux/btf_ids.h > @@ -0,0 +1,69 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#ifndef _LINUX_BTF_IDS_H > +#define _LINUX_BTF_IDS_H 1 this "1", is it necessary? I think it's always just `#define HEADER_GUARD`? > + > +#include <linux/compiler.h> /* for __PASTE */ > + [...] > +#define __BTF_ID_LIST(name) \ > +asm( \ > +".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ > +".local " #name "; \n" \ > +#name ":; \n" \ > +".popsection; \n"); \ > + > +#define BTF_ID_LIST(name) \ > +__BTF_ID_LIST(name) \ > +extern int name[]; nit: extern u32 (or __u32) perhaps? > + > +#endif > -- > 2.25.4 >
On Fri, Jun 26, 2020 at 02:32:48PM -0700, Andrii Nakryiko wrote: SNIP > > [...] > > > diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h > > new file mode 100644 > > index 000000000000..f7f9dc4d9a9f > > --- /dev/null > > +++ b/include/linux/btf_ids.h > > @@ -0,0 +1,69 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > + > > +#ifndef _LINUX_BTF_IDS_H > > +#define _LINUX_BTF_IDS_H 1 > > this "1", is it necessary? I think it's always just `#define HEADER_GUARD`? I followed btf.h header: #ifndef _LINUX_BTF_H #define _LINUX_BTF_H 1 I don't mind changing it > > > + > > +#include <linux/compiler.h> /* for __PASTE */ > > + > > [...] > > > +#define __BTF_ID_LIST(name) \ > > +asm( \ > > +".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ > > +".local " #name "; \n" \ > > +#name ":; \n" \ > > +".popsection; \n"); \ > > + > > +#define BTF_ID_LIST(name) \ > > +__BTF_ID_LIST(name) \ > > +extern int name[]; > > nit: extern u32 (or __u32) perhaps? right, should be u32 thanks, jirka
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index db600ef218d7..a9b77a4314a8 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -641,6 +641,10 @@ __start_BTF = .; \ *(.BTF) \ __stop_BTF = .; \ + } \ + . = ALIGN(4); \ + .BTF.ids : AT(ADDR(.BTF.ids) - LOAD_OFFSET) { \ + *(.BTF.ids) \ } #else #define BTF diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h new file mode 100644 index 000000000000..f7f9dc4d9a9f --- /dev/null +++ b/include/linux/btf_ids.h @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_BTF_IDS_H +#define _LINUX_BTF_IDS_H 1 + +#include <linux/compiler.h> /* for __PASTE */ + +/* + * Following macros help to define lists of BTF IDs placed + * in .BTF_ids section. They are initially filled with zeros + * (during compilation) and resolved later during the + * linking phase by btfid tool. + * + * Any change in list layout must be reflected in btfid + * tool logic. + */ + +#define BTF_IDS_SECTION ".BTF.ids" + +#define ____BTF_ID(symbol) \ +asm( \ +".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ +".local " #symbol " ; \n" \ +".type " #symbol ", @object; \n" \ +".size " #symbol ", 4; \n" \ +#symbol ": \n" \ +".zero 4 \n" \ +".popsection; \n"); + +#define __BTF_ID(symbol) \ + ____BTF_ID(symbol) + +#define __ID(prefix) \ + __PASTE(prefix, __COUNTER__) + +/* + * The BTF_ID defines unique symbol for each ID pointing + * to 4 zero bytes. + */ +#define BTF_ID(prefix, name) \ + __BTF_ID(__ID(__BTF_ID__##prefix##__##name##__)) + +/* + * The BTF_ID_LIST macro defines pure (unsorted) list + * of BTF IDs, with following layout: + * + * BTF_ID_LIST(list1) + * BTF_ID(type1, name1) + * BTF_ID(type2, name2) + * + * list1: + * __BTF_ID__type1__name1__1: + * .zero 4 + * __BTF_ID__type2__name2__2: + * .zero 4 + * + */ +#define __BTF_ID_LIST(name) \ +asm( \ +".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ +".local " #name "; \n" \ +#name ":; \n" \ +".popsection; \n"); \ + +#define BTF_ID_LIST(name) \ +__BTF_ID_LIST(name) \ +extern int name[]; + +#endif
Adding support to generate .BTF_ids section that will hold BTF ID lists for verifier. Adding macros that will help to define lists of BTF ID values placed in .BTF_ids section. They are initially filled with zeros (during compilation) and resolved later during the linking phase by resolve_btfids tool. Following defines list of one BTF ID value: BTF_ID_LIST(bpf_skb_output_btf_ids) BTF_ID(struct, sk_buff) It also defines following variable to access the list: extern int bpf_skb_output_btf_ids[]; Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- include/asm-generic/vmlinux.lds.h | 4 ++ include/linux/btf_ids.h | 69 +++++++++++++++++++++++++++++++ 2 files changed, 73 insertions(+) create mode 100644 include/linux/btf_ids.h