Re: [tip:x86/x32] x32: Fix alignment fail in struct compat_siginfo

From: H. Peter Anvin
Date: Wed Mar 14 2012 - 19:19:53 EST


On 03/14/2012 04:17 PM, H.J. Lu wrote:
>
> Just for the record, although the offsets of _utime and _stime are
> multiple of 8 bytes, struct siginfo is only aligned at 4 bytes. So
> the addresses of _utime and _stime may not be 8byte aligned.
> But misaligned int64 load/store are OK for x86-64.
>

Yes; the real question I guess is where struct siginfo appears and if it
is misaligned by construction. It obviously appears in the signal stack
frame but also in a couple of system calls. It might be possible to put
an __attribute__((aligned(8))) on the whole structure in the x32 case?

-hpa
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