linux-kernel - Re: [PATCH] x86/perf: Add hardware performance events support for Zhaoxin CPU.

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Message-ID: <a4e4ee8a-bce8-64da-891e-c2705181f7da@zhaoxin.com>
Date:   Thu, 16 Apr 2020 14:16:32 +0800
From:   CodyYao-oc <CodyYao-oc@...oxin.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...hat.com>, <namhyung@...nel.org>, <tglx@...utronix.de>,
        <x86@...nel.org>, <hpa@...or.com>, <linux-kernel@...r.kernel.org>,
        <cooperyan@...oxin.com>, <codyyao@...oxin.com>
Subject: Re: [PATCH] x86/perf: Add hardware performance events support for
 Zhaoxin CPU.

On 2020/4/15 下午5:36, Borislav Petkov wrote:
> On Mon, Apr 13, 2020 at 11:14:29AM +0800, CodyYao-oc wrote:
>> Zhaoxin CPU has provided facilities for monitoring performance
>> via PMU(Performance Monitor Unit), but the functionality is unused so far.
>> Therefore, add support for zhaoxin pmu to make performance related
>> hardware events available.
>>
>> Signed-off-by: CodyYao-oc <CodyYao-oc@...oxin.com>
>> Reported-by: kbuild test robot <lkp@...el.com>
> 
> What exactly did the 0day bot report?
> 
> Put that in []
> 
> above the Reported-by line pls.
> 

Dear Boris,

It's a warning message about uninitialized variable, paste the log 
below, sorry for missing it.

Furthermore, it will disappear on next version patch because of the code 
changes, anyway I'll paste it when resend next version patch.

[All warnings (new ones prefixed by >>):

 >> arch/x86/events/zhaoxin/core.c:362:6: warning: variable 'is_zxc' is 
used uninitialized whenever 'if' condition is false 
[-Wsometimes-uninitialized]
            if (boot_cpu_data.x86 == 0x06 &&
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
    arch/x86/events/zhaoxin/core.c:369:6: note: uninitialized use occurs 
here
            if (is_zxc)
                ^~~~~~
    arch/x86/events/zhaoxin/core.c:362:2: note: remove the 'if' if its 
condition is always true
            if (boot_cpu_data.x86 == 0x06 &&
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 >> arch/x86/events/zhaoxin/core.c:362:6: warning: variable 'is_zxc' is 
used uninitialized whenever '&&' condition is false 
[-Wsometimes-uninitialized]
            if (boot_cpu_data.x86 == 0x06 &&
                ^~~~~~~~~~~~~~~~~~~~~~~~~
    arch/x86/events/zhaoxin/core.c:369:6: note: uninitialized use occurs 
here
            if (is_zxc)
                ^~~~~~
    arch/x86/events/zhaoxin/core.c:362:6: note: remove the '&&' if its 
condition is always true
            if (boot_cpu_data.x86 == 0x06 &&
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
    arch/x86/events/zhaoxin/core.c:352:13: note: initialize the variable 
'is_zxc' to silence this warning
            bool is_zxc;
                       ^
                        = 0
    2 warnings generated.]

Reported-by:kbuild test robot<lkp@...el.com>

Thanks
Cody