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Date: Fri, 17 Jun 2016 13:24:01 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        Yury Norov <ynorov@caviumnetworks.com>,
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        Kan Liang <kan.liang@intel.com>, Wang Nan <wangnan0@huawei.com>,
        Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [PATCH] tools/perf: Fix the mask in regs_dump__printf
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On Fri, Jun 17, 2016 at 02:43:31PM +0530, Madhavan Srinivasan wrote:

SNIP

> 
>  
>                 if (data->user_regs.abi) {
> -                       u64 mask = evsel->attr.sample_regs_user;
> +                       u.val64 = evsel->attr.sample_regs_user;
>  
> -                       sz = hweight_long(mask) * sizeof(u64);
> +                       if (sizeof(u64) > sizeof(unsigned long)) {
> +                               u64 mask = u.val64;
> +                               u.val32[1] = mask >> 32;
> +                               u.val32[0] = mask & ULONG_MAX;
> +                       }
> +
> +                       sz = hweight_long(u.val64) * sizeof(u64);
>                         OVERFLOW_CHECK(array, sz, max_size);
> -                       data->user_regs.mask = mask;
> +                       data->user_regs.mask = u.val64;
>                         data->user_regs.regs = (u64 *)array;
> 
> Issue I see is when printing the mask value in a 32bit perf
> on a 64bit kernel (big endian).
> 
> 442044948492 0xdc0 [0x188]: PERF_RECORD_SAMPLE(IP, 0x1): 7299/7299:
> 0xc000000000059200 period: 12599 addr: 0
> ... intr regs: mask 0xffffffff000007ff ABI 32-bit
>                             ^^^ shld have been 0x7ffffffffff
> 
> I agree it is better to fix this when reading, but
> we need to swap again when printing?

hum, sample data should be swap at this point already..
see perf_session__process_event

jirka