Re: [PATCH bpf 1/2] samples/bpf: Set flag __SANE_USERSPACE_TYPES__ for MIPS to fix build warnings

[Tiezhu Yang]

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@xxxxxxxxxxx>
> > ---
> >   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.

Thanks,
Tiezhu

> > +
> >   #include <asm/types.h>
> >   #include <asm/posix_types.h>