netdev - Re: [PATCH net] samples/bpf: fix a build issue

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Date:   Mon, 10 Jul 2017 13:51:45 -0700
From:   Yonghong Song <yhs@...com>
To:     Daniel Borkmann <daniel@...earbox.net>, <ast@...com>,
        <brakmo@...com>, <netdev@...r.kernel.org>
CC:     <kernel-team@...com>, Yonghong Song <yhs@...alhost.localdomain>
Subject: Re: [PATCH net] samples/bpf: fix a build issue



On 7/10/17 1:27 PM, Daniel Borkmann wrote:
> On 07/10/2017 10:12 PM, Yonghong Song wrote:
>> From: Yonghong Song <yhs@...alhost.localdomain>
>>
>> With latest net-next:
>> ====
>> clang  -nostdinc -isystem 
>> /usr/lib/gcc/x86_64-redhat-linux/6.3.1/include -I./arch/x86/include 
>> -I./arch/x86/include/generated/uapi -I./arch/x86/include/generated  
>> -I./include -I./arch/x86/include/uapi -I./include/uapi 
>> -I./include/generated/uapi -include ./include/linux/kconfig.h  
>> -Isamples/bpf \
>>     -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
>>     -Wno-compare-distinct-pointer-types \
>>     -Wno-gnu-variable-sized-type-not-at-end \
>>     -Wno-address-of-packed-member -Wno-tautological-compare \
>>     -Wno-unknown-warning-option \
>>     -O2 -emit-llvm -c samples/bpf/tcp_synrto_kern.c -o -| llc 
>> -march=bpf -filetype=obj -o samples/bpf/tcp_synrto_kern.o
>> samples/bpf/tcp_synrto_kern.c:20:10: fatal error: 'bpf_endian.h' file 
>> not found
>>           ^~~~~~~~~~~~~~
>> 1 error generated.
>> ====
>>
>> net has the same issue.
>>
>> Add support for ntohl and htonl in 
>> tools/testing/selftests/bpf/bpf_endian.h
>> and move it to samples/bpf/ directory so that it can used by
>> both selftests/bpf and samples/bpf. The existing 
>> samples/bpf/bpf_helpers.h
>> is already used by both.
>>
>> Signed-off-by: Yonghong Song <yhs@...com>
>> ---
>>   {tools/testing/selftests => samples}/bpf/bpf_endian.h | 14 
>> ++++++++++++++
> 
> samples/bpf/Makefile already does:
> 
>    HOSTCFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
> 
> If needed we should rather extend the sample's Makefile to pull in
> bpf_endian.h also for clang generated files, but not the other way
> round. It's both kind of messy, but kernel selftests should not need
> to include or depend upon some sample code.

Sounds good. I will then move bpf_helpers.h to selftests as well so
samples/bpf will depend on selftests/bpf, but not the other way around.

> 
> Other than that looks good to me.
> 
>>   tools/testing/selftests/bpf/Makefile                  |  3 ++-
>>   2 files changed, 16 insertions(+), 1 deletion(-)
>>   rename {tools/testing/selftests => samples}/bpf/bpf_endian.h (73%)
>>
>> diff --git a/tools/testing/selftests/bpf/bpf_endian.h 
>> b/samples/bpf/bpf_endian.h
>> similarity index 73%
>> rename from tools/testing/selftests/bpf/bpf_endian.h
>> rename to samples/bpf/bpf_endian.h
>> index 487cbfb..74af266 100644
>> --- a/tools/testing/selftests/bpf/bpf_endian.h
>> +++ b/samples/bpf/bpf_endian.h
>> @@ -23,11 +23,19 @@
>>   # 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)
>>   #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)
>>   #else
>>   # error "Fix your compiler's __BYTE_ORDER__?!"
>>   #endif
>> @@ -38,5 +46,11 @@
>>   #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__ */
>> diff --git a/tools/testing/selftests/bpf/Makefile 
>> b/tools/testing/selftests/bpf/Makefile
>> index 2ca51a8..f263c6b 100644
>> --- a/tools/testing/selftests/bpf/Makefile
>> +++ b/tools/testing/selftests/bpf/Makefile
>> @@ -8,7 +8,8 @@ ifneq ($(wildcard $(GENHDR)),)
>>     GENFLAGS := -DHAVE_GENHDR
>>   endif
>>
>> -CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) 
>> -I../../../include
>> +CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) 
>> -I../../../include \
>> +    -I../../../../samples/bpf
>>   LDLIBS += -lcap -lelf
>>
>>   TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map 
>> test_lpm_map test_progs \
>>
>