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| author |   Andrii Nakryiko <andrii@kernel.org> | 2021-09-28 09:19:42 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2021-09-28 13:51:19 -0700 |
| commit | 13d35a0cf1741431333ba4aa9bce9c5bbc88f63b (patch) | |
| tree | 2eaa7f8f88aca32b742625b150891e4958d4a51a /tools/lib/bpf/libbpf_internal.h | |
| parent | libbpf: Refactor internal sec_def handling to enable pluggability (diff) | |
| download | linux-dev-13d35a0cf1741431333ba4aa9bce9c5bbc88f63b.tar.xz linux-dev-13d35a0cf1741431333ba4aa9bce9c5bbc88f63b.zip | |
libbpf: Reduce reliance of attach_fns on sec_def internals
Move closer to not relying on bpf_sec_def internals that won't be part
of public API, when pluggable SEC() handlers will be allowed. Drop
pre-calculated prefix length, and in various helpers don't rely on this
prefix length availability. Also minimize reliance on knowing
bpf_sec_def's prefix for few places where section prefix shortcuts are
supported (e.g., tp vs tracepoint, raw_tp vs raw_tracepoint).
Given checking some string for having a given string-constant prefix is
such a common operation and so annoying to be done with pure C code, add
a small macro helper, str_has_pfx(), and reuse it throughout libbpf.c
where prefix comparison is performed. With __builtin_constant_p() it's
possible to have a convenient helper that checks some string for having
a given prefix, where prefix is either string literal (or compile-time
known string due to compiler optimization) or just a runtime string
pointer, which is quite convenient and saves a lot of typing and string
literal duplication.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20210928161946.2512801-7-andrii@kernel.org
Diffstat (limited to 'tools/lib/bpf/libbpf_internal.h')
| -rw-r--r-- | tools/lib/bpf/libbpf_internal.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index ceb0c98979bc..ec79400517d4 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -89,6 +89,13 @@ (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD)) #endif +/* Check whether a string `str` has prefix `pfx`, regardless if `pfx` is + * a string literal known at compilation time or char * pointer known only at + * runtime. + */ +#define str_has_pfx(str, pfx) \ + (strncmp(str, pfx, __builtin_constant_p(pfx) ? sizeof(pfx) - 1 : strlen(pfx)) == 0) + /* Symbol versioning is different between static and shared library. * Properly versioned symbols are needed for shared library, but * only the symbol of the new version is needed for static library. |