From f80442a4cd1864154beaa060bb483a2c9f7d811f Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Tue, 22 May 2018 14:57:18 -0700 Subject: bpf: btf: Change how section is supported in btf_header There are currently unused section descriptions in the btf_header. Those sections are here to support future BTF use cases. For example, the func section (func_off) is to support function signature (e.g. the BPF prog function signature). Instead of spelling out all potential sections up-front in the btf_header. This patch makes changes to btf_header such that extending it (e.g. adding a section) is possible later. The unused ones can be removed for now and they can be added back later. This patch: 1. adds a hdr_len to the btf_header. It will allow adding sections (and other info like parent_label and parent_name) later. The check is similar to the existing bpf_attr. If a user passes in a longer hdr_len, the kernel ensures the extra tailing bytes are 0. 2. allows the section order in the BTF object to be different from its sec_off order in btf_header. 3. each sec_off is followed by a sec_len. It must not have gap or overlapping among sections. The string section is ensured to be at the end due to the 4 bytes alignment requirement of the type section. The above changes will allow enough flexibility to add new sections (and other info) to the btf_header later. This patch also removes an unnecessary !err check at the end of btf_parse(). Signed-off-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann --- include/uapi/linux/btf.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'include/uapi') diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h index bcb56ee47014..4fa479741a02 100644 --- a/include/uapi/linux/btf.h +++ b/include/uapi/linux/btf.h @@ -12,15 +12,11 @@ struct btf_header { __u16 magic; __u8 version; __u8 flags; - - __u32 parent_label; - __u32 parent_name; + __u32 hdr_len; /* All offsets are in bytes relative to the end of this header */ - __u32 label_off; /* offset of label section */ - __u32 object_off; /* offset of data object section*/ - __u32 func_off; /* offset of function section */ __u32 type_off; /* offset of type section */ + __u32 type_len; /* length of type section */ __u32 str_off; /* offset of string section */ __u32 str_len; /* length of string section */ }; -- cgit v1.2.3