Message-ID: <1437037461.15828.2.camel@ellerman.id.au>
Subject: Re: BUG: perf error on syscalls for powerpc64.
From: Michael Ellerman <mpe@ellerman.id.au>
To: Zumeng Chen <zumeng.chen@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        romeo.cane.ext@coriant.com, imunsie@au1.ibm.com, paulus@samba.org,
        benh@kernel.crashing.org
Date: Thu, 16 Jul 2015 19:04:21 +1000
In-Reply-To: <CA+Y31wfLFe11nh9AVs2JgKrxpMc6qxxDyCfey52HT23S7RJ_zw@mail.gmail.com>
References: <CA+Y31wfLFe11nh9AVs2JgKrxpMc6qxxDyCfey52HT23S7RJ_zw@mail.gmail.com>
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On Thu, 2015-07-16 at 13:57 +0800, Zumeng Chen wrote:
> Hi All,
> 
> 1028ccf5 did a change for sys_call_table from a pointer to an array of
> unsigned long, I think it's not proper, here is my reason:
> 
> sys_call_table defined as a label in assembler should be pointer array
> rather than an array as described in 1028ccf5. If we defined it as an
> array, then arch_syscall_addr will return the address of sys_call_table[],
> actually the content of sys_call_table[] is demanded by arch_syscall_addr.
> so 'perf list' will ignore all syscalls since find_syscall_meta will
> return null
> in init_ftrace_syscalls because of the wrong arch_syscall_addr.
> 
> Did I miss something, or Gcc compiler has done something newer ?

Hi Zumeng,

It works for me with the code as it is in mainline.

I don't quite follow your explanation, so if you're seeing a bug please send
some information about what you're actually seeing. And include the disassembly
of arch_syscall_addr() and your compiler version etc.

cheers


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