From: Yonghong Song <yhs@fb.com>
To: Tiezhu Yang <yangtiezhu@loongson.cn>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>
Cc: <linux-sparse@vger.kernel.org>, <netdev@vger.kernel.org>,
<bpf@vger.kernel.org>, <clang-built-linux@googlegroups.com>,
<linux-mips@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Xuefeng Li <lixuefeng@loongson.cn>
Subject: Re: [PATCH bpf 1/2] samples/bpf: Set flag __SANE_USERSPACE_TYPES__ for MIPS to fix build warnings
Date: Mon, 18 Jan 2021 10:44:34 -0800 [thread overview]
Message-ID: <313a7ed5-a34d-5eed-4715-06fed4a75c40@fb.com> (raw)
In-Reply-To: <f077bcae-97be-fc7f-c3fa-c6026bfe25d2@loongson.cn>
On 1/17/21 7:22 PM, Tiezhu Yang wrote:
> On 01/14/2021 01:12 AM, Yonghong Song wrote:
>>
>>
>> On 1/13/21 2:57 AM, Tiezhu Yang wrote:
>>> MIPS needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
>>> 'int-ll64.h' in arch/mips/include/uapi/asm/types.h and avoid compile
>>> warnings when printing __u64 with %llu, %llx or %lld.
>>
>> could you mention which command produces the following warning?
>
> make M=samples/bpf
>
>>
>>>
>>> printf("0x%02x : %llu\n", key, value);
>>> ~~~^ ~~~~~
>>> %lu
>>> printf("%s/%llx;", sym->name, addr);
>>> ~~~^ ~~~~
>>> %lx
>>> printf(";%s %lld\n", key->waker, count);
>>> ~~~^ ~~~~~
>>> %ld
>>>
>>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>>> ---
>>> samples/bpf/Makefile | 4 ++++
>>> tools/include/linux/types.h | 3 +++
>>> 2 files changed, 7 insertions(+)
>>>
>>> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
>>> index 26fc96c..27de306 100644
>>> --- a/samples/bpf/Makefile
>>> +++ b/samples/bpf/Makefile
>>> @@ -183,6 +183,10 @@ BPF_EXTRA_CFLAGS := $(ARM_ARCH_SELECTOR)
>>> TPROGS_CFLAGS += $(ARM_ARCH_SELECTOR)
>>> endif
>>> +ifeq ($(ARCH), mips)
>>> +TPROGS_CFLAGS += -D__SANE_USERSPACE_TYPES__
>>> +endif
>>> +
>>
>> This change looks okay based on description in
>> arch/mips/include/uapi/asm/types.h
>>
>> '''
>> /*
>> * We don't use int-l64.h for the kernel anymore but still use it for
>> * userspace to avoid code changes.
>> *
>> * However, some user programs (e.g. perf) may not want this. They can
>> * flag __SANE_USERSPACE_TYPES__ to get int-ll64.h here.
>> */
>> '''
>>
>>> TPROGS_CFLAGS += -Wall -O2
>>> TPROGS_CFLAGS += -Wmissing-prototypes
>>> TPROGS_CFLAGS += -Wstrict-prototypes
>>> diff --git a/tools/include/linux/types.h b/tools/include/linux/types.h
>>> index 154eb4e..e9c5a21 100644
>>> --- a/tools/include/linux/types.h
>>> +++ b/tools/include/linux/types.h
>>> @@ -6,7 +6,10 @@
>>> #include <stddef.h>
>>> #include <stdint.h>
>>> +#ifndef __SANE_USERSPACE_TYPES__
>>> #define __SANE_USERSPACE_TYPES__ /* For PPC64, to get LL64 types */
>>> +#endif
>>
>> What problem this patch fixed?
>
> If add "TPROGS_CFLAGS += -D__SANE_USERSPACE_TYPES__" in
> samples/bpf/Makefile, it appears the following error:
>
> Auto-detecting system features:
> ... libelf: [ on ]
> ... zlib: [ on ]
> ... bpf: [ OFF ]
>
> BPF API too old
> make[3]: *** [Makefile:293: bpfdep] Error 1
> make[2]: *** [Makefile:156: all] Error 2
>
> With #ifndef __SANE_USERSPACE_TYPES__ in tools/include/linux/types.h,
> the above error has gone.
>
>> If this header is used, you can just
>> change comment from "PPC64" to "PPC64/MIPS", right?
>
> If include <linux/types.h> in the source files which have compile warnings
> when printing __u64 with %llu, %llx or %lld, it has no effect due to
> actually
> it includes usr/include/linux/types.h instead of
> tools/include/linux/types.h,
> this is because the include-directories in samples/bpf/Makefile are
> searched
> in the order, -I./usr/include is in the front of -I./tools/include.
>
> So I think define __SANE_USERSPACE_TYPES__ for MIPS in samples/bpf/Makefile
> is proper, at the same time, add #ifndef __SANE_USERSPACE_TYPES__ in
> tools/include/linux/types.h can avoid build error and have no side effect.
>
> I will send v2 later with mention in the commit message that this is
> mips related.
It would be good if you can add the above information to the commit
message so people will know what the root cause of the issue.
If I understand correctly, if we could have include path
"tools/include" earlier than "usr/include", we might not have this
issue. The problem is that "usr/include" is preferred first (uapi)
than "tools/include" (including kernel dev headers).
I am wondering whether we could avoid changes in
tools/include/linux/types.h, e.g., by undef __SANE_USER_SPACE_TYPES
right before include
path tools/include. But that sounds like a ugly hack and actually
the change in tools/include/linux/types.h does not hurt other
compilations.
So your current change looks good to me, but please have better
explanation of the problem and why for each change in the commit
message.
>
> Thanks,
> Tiezhu
>
>>
>>> +
>>> #include <asm/types.h>
>>> #include <asm/posix_types.h>
>>>
>
next prev parent reply other threads:[~2021-01-18 18:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 10:57 [PATCH 0/2] Fix build errors and warnings when make M=samples/bpf Tiezhu Yang
2021-01-13 10:57 ` [PATCH bpf 1/2] samples/bpf: Set flag __SANE_USERSPACE_TYPES__ for MIPS to fix build warnings Tiezhu Yang
2021-01-13 17:12 ` Yonghong Song
2021-01-18 3:22 ` Tiezhu Yang
2021-01-18 18:44 ` Yonghong Song [this message]
2021-01-13 10:57 ` [PATCH 2/2] compiler.h: Include asm/rwonce.h under ARM64 and ALPHA to fix build errors Tiezhu Yang
2021-01-13 17:14 ` Yonghong Song
2021-01-18 9:25 ` Tiezhu Yang
2021-01-14 8:40 ` Sergei Shtylyov
2021-01-13 17:16 ` [PATCH 0/2] Fix build errors and warnings when make M=samples/bpf Yonghong Song
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