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From: Daniel Borkmann <daniel@iogearbox.net>
To: Yaniv Agman <yanivagman@gmail.com>
Cc: bpf <bpf@vger.kernel.org>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Yonghong Song <yhs@fb.com>
Subject: Re: libbpf error: unknown register name 'r0' in asm
Date: Fri, 9 Oct 2020 20:21:13 +0200	[thread overview]
Message-ID: <e385d737-1a4b-a1b6-9a2e-23a71d2ca1b7@iogearbox.net> (raw)
In-Reply-To: <CAMy7=ZV5pZzzs_vuqn1eqEe9tBjgmQHT=hv0CXhgxYrjO_8wZg@mail.gmail.com>

On 10/9/20 8:09 PM, Yaniv Agman wrote:
> ‫בתאריך יום ו׳, 9 באוק׳ 2020 ב-20:39 מאת ‪Daniel Borkmann‬‏
> <‪daniel@iogearbox.net‬‏>:‬
>>
>> On 10/9/20 6:56 PM, Yaniv Agman wrote:
>>> ‫בתאריך יום ו׳, 9 באוק׳ 2020 ב-19:27 מאת ‪Daniel Borkmann‬‏
>>> <‪daniel@iogearbox.net‬‏>:‬
>>>>
>>>> [ Cc +Yonghong ]
>>>>
>>>> On 10/9/20 6:05 PM, Yaniv Agman wrote:
>>>>> Pulling the latest changes of libbpf and compiling my application with it,
>>>>> I see the following error:
>>>>>
>>>>> ../libbpf/src//root/usr/include/bpf/bpf_helpers.h:99:10: error:
>>>>> unknown register name 'r0' in asm
>>>>>                         : "r0", "r1", "r2", "r3", "r4", "r5");
>>>>>
>>>>> The commit which introduced this change is:
>>>>> 80c7838600d39891f274e2f7508b95a75e4227c1
>>>>>
>>>>> I'm not sure if I'm doing something wrong (missing include?), or this
>>>>> is a genuine error
>>>>
>>>> Seems like your clang/llvm version might be too old.
>>>
>>> I'm using clang 10.0.1
>>
>> Ah, okay, I see. Would this diff do the trick for you?
> 
> Yes! Now it compiles without any problems!

Great, thx, I'll cook proper fix and check with clang6 as Yonghong mentioned.

>> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
>> index 2bdb7d6dbad2..31e356831fcf 100644
>> --- a/tools/lib/bpf/bpf_helpers.h
>> +++ b/tools/lib/bpf/bpf_helpers.h
>> @@ -72,6 +72,7 @@
>>    /*
>>     * Helper function to perform a tail call with a constant/immediate map slot.
>>     */
>> +#if __clang_major__ >= 10 && defined(__bpf__)
>>    static __always_inline void
>>    bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
>>    {
>> @@ -98,6 +99,9 @@ bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
>>                       :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
>>                       : "r0", "r1", "r2", "r3", "r4", "r5");
>>    }
>> +#else
>> +# define bpf_tail_call_static  bpf_tail_call
>> +#endif /* __clang_major__ >= 10 && __bpf__ */
>>
>>    /*
>>     * Helper structure used by eBPF C program


  reply	other threads:[~2020-10-09 18:21 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09 16:05 libbpf error: unknown register name 'r0' in asm Yaniv Agman
2020-10-09 16:27 ` Daniel Borkmann
2020-10-09 16:56   ` Yaniv Agman
2020-10-09 17:39     ` Daniel Borkmann
2020-10-09 18:09       ` Yaniv Agman
2020-10-09 18:21         ` Daniel Borkmann [this message]
2020-10-09 18:33           ` Yaniv Agman
2020-10-09 18:39             ` Andrii Nakryiko
2020-10-09 19:32               ` Yaniv Agman
2020-10-09 19:53                 ` Andrii Nakryiko
2020-10-09 20:24                   ` Yaniv Agman
2020-10-12 20:03                     ` Andrii Nakryiko
2020-10-12 21:48                       ` Yaniv Agman
2020-10-12 22:16                         ` Andrii Nakryiko
2020-10-09 18:35           ` Andrii Nakryiko
2020-10-09 18:41             ` Daniel Borkmann
2020-10-09 18:59               ` Andrii Nakryiko
2020-10-09 19:08                 ` Yonghong Song
2020-10-09 19:33                   ` Yaniv Agman
2020-10-09 19:58                     ` Daniel Borkmann
2020-10-21  9:43                       ` Yaniv Agman
2020-10-21 17:18                         ` Daniel Borkmann
2020-10-21 19:33                           ` Yaniv Agman
2020-10-09 17:41   ` Yonghong Song
2020-10-09 18:03 ` Andrii Nakryiko
2020-10-09 18:12   ` Yaniv Agman

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