From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Shuah Khan <shuah@kernel.org>, Alexei Starovoitov <ast@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
linux-kselftest@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: [PATCHv2 bpf-next 1/3] bpf, tests: tweak endianness selection
Date: Wed, 20 Mar 2019 21:53:33 +0900 [thread overview]
Message-ID: <20190320125335.19621-1-sergey.senozhatsky@gmail.com> (raw)
Not all compilers have __builtin_bswap16() and __builtin_bswap32(),
thus not all compilers are able to compile the following code:
(__builtin_constant_p(x) ? \
___constant_swab16(x) : __builtin_bswap16(x))
That's the reason why bpf_ntohl() doesn't work on GCC < 4.8, for
instance:
error: implicit declaration of function '__builtin_bswap16'
We can use __builtin_bswap16() only if compiler has this built-in,
that is, only if __HAVE_BUILTIN_BSWAP16__ is defined. Standard UAPI
__swab16()/__swab32() take care of that, and, additionally, handle
__builtin_constant_p() cases as well:
#ifdef __HAVE_BUILTIN_BSWAP16__
#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
#else
#define __swab16(x) \
(__builtin_constant_p((__u16)(x)) ? \
___constant_swab16(x) : \
__fswab16(x))
#endif
So we can tweak selftests/bpf/bpf_endian.h and use UAPI
__swab16()/__swab32().
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
v2: fixed build error, reshuffled patches (Stanislav Fomichev)
tools/testing/selftests/bpf/bpf_endian.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_endian.h b/tools/testing/selftests/bpf/bpf_endian.h
index b25595ea4a78..1ed268b2002b 100644
--- a/tools/testing/selftests/bpf/bpf_endian.h
+++ b/tools/testing/selftests/bpf/bpf_endian.h
@@ -20,12 +20,12 @@
* use different targets.
*/
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-# define __bpf_ntohs(x) __builtin_bswap16(x)
-# define __bpf_htons(x) __builtin_bswap16(x)
+# define __bpf_ntohs(x) __swab16(x)
+# define __bpf_htons(x) __swab16(x)
# define __bpf_constant_ntohs(x) ___constant_swab16(x)
# define __bpf_constant_htons(x) ___constant_swab16(x)
-# define __bpf_ntohl(x) __builtin_bswap32(x)
-# define __bpf_htonl(x) __builtin_bswap32(x)
+# define __bpf_ntohl(x) __swab32(x)
+# define __bpf_htonl(x) __swab32(x)
# define __bpf_constant_ntohl(x) ___constant_swab32(x)
# define __bpf_constant_htonl(x) ___constant_swab32(x)
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
--
2.21.0
next reply other threads:[~2019-03-20 12:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 12:53 Sergey Senozhatsky [this message]
2019-03-20 12:53 ` [PATCHv2 bpf-next 2/3] bpf, tests: drop unused __bpf_constant_foo defines Sergey Senozhatsky
2019-03-20 12:56 ` Sergey Senozhatsky
2019-03-20 12:53 ` [PATCHv2 bpf-next 3/3] bpf, tests: don't use __bpf_constant_htons() Sergey Senozhatsky
2019-03-20 12:55 ` Sergey Senozhatsky
2019-03-20 17:13 ` [PATCHv2 bpf-next 1/3] bpf, tests: tweak endianness selection Stanislav Fomichev
2019-03-20 22:20 ` Yonghong Song
2019-03-20 22:27 ` Stanislav Fomichev
2019-03-20 22:45 ` Yonghong Song
2019-03-20 23:08 ` Daniel Borkmann
2019-03-21 0:03 ` Stanislav Fomichev
2019-03-21 0:23 ` Yonghong Song
2019-03-21 0:34 ` Sergey Senozhatsky
2019-03-21 0:22 ` Sergey Senozhatsky
2019-03-21 3:24 ` Alexei Starovoitov
2019-03-21 5:08 ` Sergey Senozhatsky
2019-03-21 15:49 ` Stanislav Fomichev
2019-03-22 2:46 ` Sergey Senozhatsky
2019-03-22 3:12 ` Alexei Starovoitov
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