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| author | Alexei Starovoitov <ast@kernel.org> | 2021-12-11 17:40:23 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-12-11 17:40:23 -0800 |
| commit | 84ef3f0bb72dfcdeb7ff3e5335882f6084381437 (patch) | |
| tree | 8f12996f3395a51aed6906f48497ca3be84da125 /include | |
| parent | 259172bb6514758ce3be1610c500b51a9f44212a (diff) | |
| parent | bdbee82beca4514496c52a2dc035f2a26f0c1b88 (diff) | |
Merge branch 'introduce bpf_strncmp() helper'
Hou Tao says:
====================
Hi,
The motivation for introducing bpf_strncmp() helper comes from
two aspects:
(1) clang doesn't always replace strncmp() automatically
In tracing program, sometimes we need to using a home-made
strncmp() to check whether or not the file name is expected.
(2) the performance of home-made strncmp is not so good
As shown in the benchmark in patch #4, the performance of
bpf_strncmp() helper is 18% or 33% better than home-made strncmp()
under x86-64 or arm64 when the compared string length is 64. When
the string length grows to 4095, the performance win will be
179% or 600% under x86-64 or arm64.
Any comments are welcome.
Regards,
Tao
Change Log:
v2:
* rebased on bpf-next
* drop patch "selftests/bpf: factor out common helpers for benchmarks"
(suggested by Andrii)
* remove unnecessary inline functions and add comments for programs which
will be rejected by verifier in patch 4 (suggested by Andrii)
* rename variables used in will-fail programs to clarify the purposes.
v1: https://lore.kernel.org/bpf/20211130142215.1237217-1-houtao1@huawei.com
* change API to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2)
* add benchmark refactor and benchmark between bpf_strncmp() and strncmp()
RFC: https://lore.kernel.org/bpf/20211106132822.1396621-1-houtao1@huawei.com/
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bpf.h | 1 | ||||
| -rw-r--r-- | include/uapi/linux/bpf.h | 11 |
2 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 0ceb54c6342f..7a40022e3d00 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2163,6 +2163,7 @@ extern const struct bpf_func_proto bpf_sk_getsockopt_proto; extern const struct bpf_func_proto bpf_kallsyms_lookup_name_proto; extern const struct bpf_func_proto bpf_find_vma_proto; extern const struct bpf_func_proto bpf_loop_proto; +extern const struct bpf_func_proto bpf_strncmp_proto; const struct bpf_func_proto *tracing_prog_func_proto( enum bpf_func_id func_id, const struct bpf_prog *prog); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index c26871263f1f..2820c77e4846 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4983,6 +4983,16 @@ union bpf_attr { * Return * The number of loops performed, **-EINVAL** for invalid **flags**, * **-E2BIG** if **nr_loops** exceeds the maximum number of loops. + * + * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) + * Description + * Do strncmp() between **s1** and **s2**. **s1** doesn't need + * to be null-terminated and **s1_sz** is the maximum storage + * size of **s1**. **s2** must be a read-only string. + * Return + * An integer less than, equal to, or greater than zero + * if the first **s1_sz** bytes of **s1** is found to be + * less than, to match, or be greater than **s2**. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5167,6 +5177,7 @@ union bpf_attr { FN(kallsyms_lookup_name), \ FN(find_vma), \ FN(loop), \ + FN(strncmp), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper |