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bpf: add BPF_SIZEOF and BPF_FIELD_SIZEOF macros

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Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit
which otherwise often result in overly long bytes_to_bpf_size(sizeof())
and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro
helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF())
check in convert_bpf_extensions(), but we should rather make that generic
as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF()
users to detect any rewriter size issues at compile time. Note, there are
currently none, but we want to assert that it stays this way.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2016-09-09 02:45:29 +02:00 • committed by David S. Miller
parent 6088b5823b
commit f035a51536
3 changed files with 27 additions and 14 deletions
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14
include/linux/filter.h
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@ -314,6 +314,20 @@ struct bpf_prog_aux;
bpf_size; \
})
#define BPF_SIZEOF(type) \
({ \
const int __size = bytes_to_bpf_size(sizeof(type)); \
BUILD_BUG_ON(__size < 0); \
__size; \
})
#define BPF_FIELD_SIZEOF(type, field) \
({ \
const int __size = bytes_to_bpf_size(FIELD_SIZEOF(type, field)); \
BUILD_BUG_ON(__size < 0); \
__size; \
})
#ifdef CONFIG_COMPAT
/* A struct sock_filter is architecture independent. */
struct compat_sock_fprog {