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/linux') 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 From aea2f7b8911617d7a8c23fb73d69e78764f91b58 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Tue, 22 May 2018 14:57:20 -0700 Subject: bpf: btf: Remove unused bits from uapi/linux/btf.h This patch does the followings: 1. Limit BTF_MAX_TYPES and BTF_MAX_NAME_OFFSET to 64k. We can raise it later. 2. Remove the BTF_TYPE_PARENT and BTF_STR_TBL_ELF_ID. They are currently encoded at the highest bit of a u32. It is because the current use case does not require supporting parent type (i.e type_id referring to a type in another BTF file). It also does not support referring to a string in ELF. The BTF_TYPE_PARENT and BTF_STR_TBL_ELF_ID checks are replaced by BTF_TYPE_ID_CHECK and BTF_STR_OFFSET_CHECK which are defined in btf.c instead of uapi/linux/btf.h. 3. Limit the BTF_INFO_KIND from 5 bits to 4 bits which is enough. There is unused bits headroom if we ever needed it later. 4. The root bit in BTF_INFO is also removed because it is not used in the current use case. 5. Remove BTF_INT_VARARGS since func type is not supported now. The BTF_INT_ENCODING is limited to 4 bits instead of 8 bits. The above can be added back later because the verifier ensures the unused bits are zeros. Signed-off-by: Martin KaFai Lau Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann --- include/uapi/linux/btf.h | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h index 4fa479741a02..0b5ddbe135a4 100644 --- a/include/uapi/linux/btf.h +++ b/include/uapi/linux/btf.h @@ -22,28 +22,19 @@ struct btf_header { }; /* Max # of type identifier */ -#define BTF_MAX_TYPE 0x7fffffff +#define BTF_MAX_TYPE 0x0000ffff /* Max offset into the string section */ -#define BTF_MAX_NAME_OFFSET 0x7fffffff +#define BTF_MAX_NAME_OFFSET 0x0000ffff /* Max # of struct/union/enum members or func args */ #define BTF_MAX_VLEN 0xffff -/* The type id is referring to a parent BTF */ -#define BTF_TYPE_PARENT(id) (((id) >> 31) & 0x1) -#define BTF_TYPE_ID(id) ((id) & BTF_MAX_TYPE) - -/* String is in the ELF string section */ -#define BTF_STR_TBL_ELF_ID(ref) (((ref) >> 31) & 0x1) -#define BTF_STR_OFFSET(ref) ((ref) & BTF_MAX_NAME_OFFSET) - struct btf_type { __u32 name_off; /* "info" bits arrangement * bits 0-15: vlen (e.g. # of struct's members) * bits 16-23: unused - * bits 24-28: kind (e.g. int, ptr, array...etc) - * bits 29-30: unused - * bits 31: root + * bits 24-27: kind (e.g. int, ptr, array...etc) + * bits 28-31: unused */ __u32 info; /* "size" is used by INT, ENUM, STRUCT and UNION. @@ -58,8 +49,7 @@ struct btf_type { }; }; -#define BTF_INFO_KIND(info) (((info) >> 24) & 0x1f) -#define BTF_INFO_ISROOT(info) (!!(((info) >> 24) & 0x80)) +#define BTF_INFO_KIND(info) (((info) >> 24) & 0x0f) #define BTF_INFO_VLEN(info) ((info) & 0xffff) #define BTF_KIND_UNKN 0 /* Unknown */ @@ -84,15 +74,14 @@ struct btf_type { /* BTF_KIND_INT is followed by a u32 and the following * is the 32 bits arrangement: */ -#define BTF_INT_ENCODING(VAL) (((VAL) & 0xff000000) >> 24) +#define BTF_INT_ENCODING(VAL) (((VAL) & 0x0f000000) >> 24) #define BTF_INT_OFFSET(VAL) (((VAL & 0x00ff0000)) >> 16) #define BTF_INT_BITS(VAL) ((VAL) & 0x0000ffff) /* Attributes stored in the BTF_INT_ENCODING */ -#define BTF_INT_SIGNED 0x1 -#define BTF_INT_CHAR 0x2 -#define BTF_INT_BOOL 0x4 -#define BTF_INT_VARARGS 0x8 +#define BTF_INT_SIGNED (1 << 0) +#define BTF_INT_CHAR (1 << 1) +#define BTF_INT_BOOL (1 << 2) /* BTF_KIND_ENUM is followed by multiple "struct btf_enum". * The exact number of btf_enum is stored in the vlen (of the -- cgit v1.2.3 From 9b2cf328b2eccf761537a06bef914d2a0700fba7 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Tue, 22 May 2018 14:57:21 -0700 Subject: bpf: btf: Rename btf_key_id and btf_value_id in bpf_map_info In "struct bpf_map_info", the name "btf_id", "btf_key_id" and "btf_value_id" could cause confusion because the "id" of "btf_id" means the BPF obj id given to the BTF object while "btf_key_id" and "btf_value_id" means the BTF type id within that BTF object. To make it clear, btf_key_id and btf_value_id are renamed to btf_key_type_id and btf_value_type_id. Suggested-by: Daniel Borkmann Signed-off-by: Martin KaFai Lau Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann --- include/uapi/linux/bpf.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 97446bbe2ca5..c3e502d06bc3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -284,8 +284,8 @@ union bpf_attr { char map_name[BPF_OBJ_NAME_LEN]; __u32 map_ifindex; /* ifindex of netdev to create on */ __u32 btf_fd; /* fd pointing to a BTF type data */ - __u32 btf_key_id; /* BTF type_id of the key */ - __u32 btf_value_id; /* BTF type_id of the value */ + __u32 btf_key_type_id; /* BTF type_id of the key */ + __u32 btf_value_type_id; /* BTF type_id of the value */ }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ @@ -2219,8 +2219,8 @@ struct bpf_map_info { __u64 netns_dev; __u64 netns_ino; __u32 btf_id; - __u32 btf_key_id; - __u32 btf_value_id; + __u32 btf_key_type_id; + __u32 btf_value_type_id; } __attribute__((aligned(8))); struct bpf_btf_info { -- cgit v1.2.3