[PATCH bpf-next v2] samples/bpf: Set flag __SANE_USERSPACE_TYPES__ for MIPS to fix build warnings

From: Tiezhu Yang
Date: Mon Jan 25 2021 - 00:08:36 EST


There exists many build warnings when make M=samples/bpf on the Loongson
platform, this issue is MIPS related, x86 compiles just fine.

Here are some warnings:

CC samples/bpf/ibumad_user.o
samples/bpf/ibumad_user.c: In function ‘dump_counts’:
samples/bpf/ibumad_user.c:46:24: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘__u64’ {aka ‘long unsigned int’} [-Wformat=]
printf("0x%02x : %llu\n", key, value);
~~~^ ~~~~~
%lu
CC samples/bpf/offwaketime_user.o
samples/bpf/offwaketime_user.c: In function ‘print_ksym’:
samples/bpf/offwaketime_user.c:34:17: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘__u64’ {aka ‘long unsigned int’} [-Wformat=]
printf("%s/%llx;", sym->name, addr);
~~~^ ~~~~
%lx
samples/bpf/offwaketime_user.c: In function ‘print_stack’:
samples/bpf/offwaketime_user.c:68:17: warning: format ‘%lld’ expects argument of type ‘long long int’, but argument 3 has type ‘__u64’ {aka ‘long unsigned int’} [-Wformat=]
printf(";%s %lld\n", key->waker, count);
~~~^ ~~~~~
%ld

MIPS needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
'int-ll64.h' in arch/mips/include/uapi/asm/types.h, then it can avoid
build warnings when printing __u64 with %llu, %llx or %lld.

The header tools/include/linux/types.h defines __SANE_USERSPACE_TYPES__,
it seems that we can include <linux/types.h> in the source files which
have build warnings, but it has no effect due to actually it includes
usr/include/linux/types.h instead of tools/include/linux/types.h, the
problem is that "usr/include" is preferred first than "tools/include"
in samples/bpf/Makefile, that sounds like a ugly hack to -Itools/include
before -Iusr/include.

So define __SANE_USERSPACE_TYPES__ for MIPS in samples/bpf/Makefile
is proper, 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 and this ifndef change does not hurt other
compilations.

Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
---

v2: Update the commit message

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

--
2.1.0