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Date: Tue, 24 Mar 2015 15:28:26 -0600
From: David Ahern <david.ahern@oracle.com>
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To: Arnaldo Carvalho de Melo <acme@kernel.org>
CC: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf timechart: Fix SIBGUS error on sparc64
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On 3/24/15 3:15 PM, Arnaldo Carvalho de Melo wrote:
> /me scratches head, should be missing something embarassingly simple :-/
>

ptr = sample->raw_data + field->offset;

raw_data is *guaranteed* to be misaligned. From kernel/events/core.c:

                         struct {
                                 u32     size;
                                 u32     data;
                         } raw = {
                                 .size = sizeof(u32),
                                 .data = 0,
                         };

Raw data starts at 64-bit alignment, but that u32 means data is NOT 
8-byte aligned. :-(

David