Re: perf test LLVM failure

[Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>]

On 06/19/2017 12:29 PM, Wangnan (F) wrote:
> Hi,
> 
> Thank you for your quick reply.
> 
> The problem is caused by following relocation information:
> 
> $ readelf -a ./llvmsubtest3
> ...
>   [ 5] _ftrace_branch    PROGBITS         0000000000000000  00000260
>        00000000000000a0  0000000000000000  WA       0     0     4
> ...
> Relocation section '.relfunc=null_lseek file->f_mode offset orig' at offset 0x490 contains 4 entries:
>   Offset          Info           Type           Sym. Value    Sym. Name
> 000000000038  000b00000001 unrecognized: 1       0000000000000000 _ftrace_branch
> 0000000000b0  000b00000001 unrecognized: 1       0000000000000000 _ftrace_branch
> 000000000128  000b00000001 unrecognized: 1       0000000000000000 _ftrace_branch
> 0000000001c0  000b00000001 unrecognized: 1       0000000000000000 _ftrace_branch
> 
> Relocation section '.rel_ftrace_branch' at offset 0x4d0 contains 8 entries:
>   Offset          Info           Type           Sym. Value    Sym. Name
> 000000000000  000200000001 unrecognized: 1       0000000000000000 .L__func__.bpf_func__n
> 000000000008  000100000001 unrecognized: 1       0000000000000015 .L.str
> 000000000028  000200000001 unrecognized: 1       0000000000000000 .L__func__.bpf_func__n
> 000000000030  000100000001 unrecognized: 1       0000000000000015 .L.str
> 000000000050  000200000001 unrecognized: 1       0000000000000000 .L__func__.bpf_func__n
> 000000000058  000100000001 unrecognized: 1       0000000000000015 .L.str
> 000000000078  000200000001 unrecognized: 1       0000000000000000 .L__func__.bpf_func__n
> 000000000080  000100000001 unrecognized: 1       0000000000000015 .L.str
> ...
> 
> So I think the failure is because you enabled CONFIG_PROFILE_ALL_BRANCHES.
> 
> I can reproduce your buggy result by selecting CONFIG_PROFILE_ALL_BRANCHES in my
> kbuild:
> 
> $ ./perf test LLVM
> 35: LLVM search and compile                    :
> 35.1: Basic BPF llvm compile                    : Ok
> 35.2: kbuild searching                          : Ok
> 35.3: Compile source for BPF prologue generation: FAILED!
> 35.4: Compile source for BPF relocation         : Skip
> 
> Simply undef CONFIG_PROFILE_ALL_BRANCHES in clang opts not working because it is
> introduced by "#include <uapi/linux/fs.h>", which override cmdline options. So I
> think the best way is to undefine 'if' inside BPF script.
> 
> Please have a look on the patch I sent:
> 
> http://lkml.kernel.org/r/20170620183203.2517-1-wangnan0@huawei.com
> 
> Thank you.
> 
> 

Thank you very much for your quick fix. I can confirm that the patch
also fixes my issue on s390.


[root@s8360047 perf]# ./perf test LLVM
35: LLVM search and compile                    :
35.1: Basic BPF llvm compile                    : Ok
35.2: kbuild searching                          : Ok
35.3: Compile source for BPF prologue generation: Ok
35.4: Compile source for BPF relocation         : Ok
[root@s8360047 perf]#


You have my Tested-by/Acked-by.

-- 
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
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