Re: [PATCH 00/10] bpf samples: Uses libbpf in tools/lib to do BPF operations

[Daniel Wagner <daniel.wagner@bmw-carit.de>]

On 12/18/2015 04:04 AM, Wangnan (F) wrote:
> On 2015/12/17 21:46, Daniel Wagner wrote:
>> On 12/17/2015 11:09 AM, Wangnan (F) wrote:
>>> On 2015/12/17 16:29, Daniel Wagner wrote:
>>>> On 12/17/2015 08:03 AM, Daniel Wagner wrote:
>>>> Patch number 2 didn't apply cleanly.
>>> When you see this, could you please have a look at:
>>>
>>> /home/wagi/src/linux/samples/bpf/libbpf/feature/test-*.make.output
>>>
>>> ?
>> test-libpython.c:1:20: fatal error: Python.h: No such file or directory
> 
> So it is the content in test-all.make.output ? Then it is
> not a problem. It is only a fastpath which tries to check
> all features by one test. On most platform it would fail.

I see. 

> BPF related feature check is not in test-all. It is a potential
> bug, but I don't think it causes your problem.
> 
> Another problem is you didn't see this in the first failure:
> 
> Auto-detecting system features:
> ...                        libelf: [ on  ]
> ...                           bpf: [ on  ]
> 
> This only happen when you already have a FEATURE-DUMP.libbpf in that
> directory and it is same as the feature check result.
> 
> Could you please remove samples/bpf in your building tree and
> try again? After you see the failure, what's the content of
> 
> /home/wagi/src/linux/samples/bpf/libbpf/FEATURE-* ?

I cleanup up my tree (rm samples/bpf/ and git checkout samples/bpf) and then

$ make samples/bpf/ 
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  LD      samples/bpf/built-in.o
make -C /home/wagi/src/linux/tools/lib/bpf O=/home/wagi/src/linux/samples/bpf/libbpf CFLAGS= LDFLAGS= V=1 /home/wagi/src/linux/samples/bpf/libbpf/libbpf.a

Auto-detecting system features:
...                        libelf: [ OFF ]
...                           bpf: [ OFF ]

No libelf found
Makefile:203: recipe for target 'elfdep' failed
make[2]: *** [elfdep] Error 255
samples/bpf/Makefile:10: recipe for target 'samples/bpf/libbpf/libbpf.a' failed
make[1]: *** [samples/bpf/libbpf/libbpf.a] Error 2
Makefile:1550: recipe for target 'samples/bpf/' failed
make: *** [samples/bpf/] Error 2

$ cat /home/wagi/src/linux/samples/bpf/libbpf/FEATURE-*
feature-libelf(0) feature-bpf(0)

$ make -C /home/wagi/src/linux/tools/lib/bpf O=/home/wagi/src/linux/samples/bpf/libbpf CFLAGS= LDFLAGS= V=1 /home/wagi/src/linux/samples/bpf/libbpf/libbpf.a
make: Entering directory '/home/wagi/src/linux/tools/lib/bpf'

Auto-detecting system features:
...                        libelf: [ on  ]
...                           bpf: [ on  ]

make -f /home/wagi/src/linux/tools/build/Makefile.build dir=. obj=libbpf
  gcc -Wp,-MD,/home/wagi/src/linux/samples/bpf/libbpf/.libbpf.o.d,-MT,/home/wagi/src/linux/samples/bpf/libbpf/libbpf.o  -DHAVE_LIBELF_MMAP_SUPPORT -DHAVE_ELF_GETPHDRNUM_SUPPORT -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat-y2k -Winit-self -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-system-headers -Wold-style-definition -Wpacked -Wredundant-decls -Wshadow -Wstrict-aliasing=3 -Wstrict-prototypes -Wswitch-default -Wswitch-enum -Wundef -Wwrite-strings -Wformat -Werror -Wall -fPIC -I. -I/home/wagi/src/linux/tools/include -I/home/wagi/src/linux/arch//include/uapi -I/home/wagi/src/linux/include/uapi -D"BUILD_STR(s)=#s"   -c -o /home/wagi/src/linux/samples/bpf/libbpf/libbpf.o libbpf.c
  gcc -Wp,-MD,/home/wagi/src/linux/samples/bpf/libbpf/.bpf.o.d,-MT,/home/wagi/src/linux/samples/bpf/libbpf/bpf.o  -DHAVE_LIBELF_MMAP_SUPPORT -DHAVE_ELF_GETPHDRNUM_SUPPORT -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat-y2k -Winit-self -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-system-headers -Wold-style-definition -Wpacked -Wredundant-decls -Wshadow -Wstrict-aliasing=3 -Wstrict-prototypes -Wswitch-default -Wswitch-enum -Wundef -Wwrite-strings -Wformat -Werror -Wall -fPIC -I. -I/home/wagi/src/linux/tools/include -I/home/wagi/src/linux/arch//include/uapi -I/home/wagi/src/linux/include/uapi -D"BUILD_STR(s)=#s"   -c -o /home/wagi/src/linux/samples/bpf/libbpf/bpf.o bpf.c
   ld -r -o /home/wagi/src/linux/samples/bpf/libbpf/libbpf-in.o  /home/wagi/src/linux/samples/bpf/libbpf/libbpf.o /home/wagi/src/linux/samples/bpf/libbpf/bpf.o
rm -f /home/wagi/src/linux/samples/bpf/libbpf/libbpf.a; ar rcs /home/wagi/src/linux/samples/bpf/libbpf/libbpf.a /home/wagi/src/linux/samples/bpf/libbpf/libbpf-in.o
make: Leaving directory '/home/wagi/src/linux/tools/lib/bpf' 

$  make samples/bpf/
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  HOSTCC  samples/bpf/test_verifier.o
  HOSTLD  samples/bpf/test_verifier
  HOSTCC  samples/bpf/test_maps.o
  HOSTLD  samples/bpf/test_maps
  HOSTCC  samples/bpf/sock_example.o
  HOSTCC  samples/bpf/utils.o
  HOSTLD  samples/bpf/sock_example
  HOSTCC  samples/bpf/fds_example.o
  HOSTLD  samples/bpf/fds_example
  HOSTCC  samples/bpf/sockex1_user.o
  HOSTLD  samples/bpf/sockex1
  HOSTCC  samples/bpf/sockex2_user.o
  HOSTLD  samples/bpf/sockex2
  HOSTCC  samples/bpf/sockex3_user.o
  HOSTLD  samples/bpf/sockex3
  HOSTCC  samples/bpf/tracex1_user.o
  HOSTLD  samples/bpf/tracex1
  HOSTCC  samples/bpf/tracex2_user.o
  HOSTLD  samples/bpf/tracex2
  HOSTCC  samples/bpf/tracex3_user.o
  HOSTLD  samples/bpf/tracex3
  HOSTCC  samples/bpf/tracex4_user.o
  HOSTLD  samples/bpf/tracex4
  HOSTCC  samples/bpf/tracex5_user.o
  HOSTLD  samples/bpf/tracex5
  HOSTCC  samples/bpf/tracex6_user.o
  HOSTLD  samples/bpf/tracex6
  HOSTCC  samples/bpf/trace_output_user.o
  HOSTLD  samples/bpf/trace_output
  HOSTCC  samples/bpf/lathist_user.o
  HOSTLD  samples/bpf/lathist
clang  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/5.1.1/include -I./arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated  -Iinclude -I./arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I./include/uapi -Iinclude/generated/uapi -include ./include/linux/kconfig.h  \
        -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
        -O2 -emit-llvm -c samples/bpf/sockex1_kern.c -o -| ./tools/bpf/llvm/bld/Debug+Asserts/bin/llc -march=bpf -filetype=obj -o samples/bpf/sockex1_kern.o
/bin/sh: line 2: ./tools/bpf/llvm/bld/Debug+Asserts/bin/llc: No such file or directory
clang: error: unable to execute command: Broken pipe
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 3.5.0 (tags/RELEASE_350/final)
Target: x86_64-redhat-linux-gnu
Thread model: posix
clang: note: diagnostic msg: PLEASE submit a bug report to http://llvm.org/bugs/ and include the crash backtrace, preprocessed source, and associated run script.
clang: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/sockex1_kern-d40fee.c
clang: note: diagnostic msg: /tmp/sockex1_kern-d40fee.sh
clang: note: diagnostic msg: 

********************
samples/bpf/Makefile:83: recipe for target 'samples/bpf/sockex1_kern.o' failed
make[1]: *** [samples/bpf/sockex1_kern.o] Error 127
Makefile:1550: recipe for target 'samples/bpf/' failed


So the last error is clear. llc is missing I need to rebuild it. 
There is something funny going on for the first call 'make samples/bpf/'.