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Message-Id: <20190319023331.23207-1-sergey.senozhatsky@gmail.com>
Date: Tue, 19 Mar 2019 11:33:31 +0900
From: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To: Shuah Khan <shuah@...nel.org>, Alexei Starovoitov <ast@...nel.org>
Cc: Stanislav Fomichev <sdf@...gle.com>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
linux-kselftest@...r.kernel.org, netdev@...r.kernel.org,
bpf@...r.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: [PATCH] bpf, tests: tweak endianness selection
Not all compilers have __builtin_bswap16() and __builtin_bswap32(),
thus not all compilers are able to compile the following code
(bpf_htons):
(__builtin_constant_p(x) ? \
___constant_swab16(x) : __builtin_bswap16(x))
That's why, for instance, bpf_htons() doesn't work on GCC < 4.8:
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 (if compiler doesn't provide
builtin bswap with constants folding):
#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@...il.com>
---
tools/testing/selftests/bpf/bpf_endian.h | 37 +++++-------------------
1 file changed, 8 insertions(+), 29 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_endian.h b/tools/testing/selftests/bpf/bpf_endian.h
index b25595ea4a78..ba06222963d5 100644
--- a/tools/testing/selftests/bpf/bpf_endian.h
+++ b/tools/testing/selftests/bpf/bpf_endian.h
@@ -20,38 +20,17 @@
* 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_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_constant_ntohl(x) ___constant_swab32(x)
-# define __bpf_constant_htonl(x) ___constant_swab32(x)
+# define bpf_ntohs(x) __swab16(x)
+# define bpf_htons(x) __swab16(x)
+# define bpf_ntohl(x) __swab32(x)
+# define bpf_htonl(x) __swab32(x)
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
-# define __bpf_ntohs(x) (x)
-# define __bpf_htons(x) (x)
-# define __bpf_constant_ntohs(x) (x)
-# define __bpf_constant_htons(x) (x)
-# define __bpf_ntohl(x) (x)
-# define __bpf_htonl(x) (x)
-# define __bpf_constant_ntohl(x) (x)
-# define __bpf_constant_htonl(x) (x)
+# define bpf_ntohs(x) (x)
+# define bpf_htons(x) (x)
+# define bpf_ntohl(x) (x)
+# define bpf_htonl(x) (x)
#else
# error "Fix your compiler's __BYTE_ORDER__?!"
#endif
-#define bpf_htons(x) \
- (__builtin_constant_p(x) ? \
- __bpf_constant_htons(x) : __bpf_htons(x))
-#define bpf_ntohs(x) \
- (__builtin_constant_p(x) ? \
- __bpf_constant_ntohs(x) : __bpf_ntohs(x))
-#define bpf_htonl(x) \
- (__builtin_constant_p(x) ? \
- __bpf_constant_htonl(x) : __bpf_htonl(x))
-#define bpf_ntohl(x) \
- (__builtin_constant_p(x) ? \
- __bpf_constant_ntohl(x) : __bpf_ntohl(x))
-
#endif /* __BPF_ENDIAN__ */
--
2.21.0
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