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Date: Tue, 23 Nov 2021 21:22:24 +0100
From: Florian Weimer <fweimer@...hat.com>
To: Rich Felker <dalias@...c.org>
Cc: musl@...ts.openwall.com
Subject: Re: __WORDSIZE on x32

* Rich Felker:

> On Tue, Nov 23, 2021 at 08:51:36PM +0100, Florian Weimer wrote:
>> This looks a bid suspicious:
>
> Come on, you missed a chance to say "sus". :-)

Sorry?  I typo'ed “bit”, but that's not it?

>> arch/x32/bits/reg.h:#undef __WORDSIZE
>> arch/x32/bits/reg.h:#define __WORDSIZE 32
>> arch/x32/bits/user.h:#undef __WORDSIZE
>> arch/x32/bits/user.h:#define __WORDSIZE 64
>> 
>> I don't know if it causes any actual problems.  I discovered it while
>> checking whether musl defines/uses __WORDSIZE.
>
> Thanks for the find. Now... which is it supposed to be?
>
> commit 664cd341921007cea52c8891f27ce35927dca378 introduced x32 as a
> patch against a copy of x86_64 and changed one instance from 64 to 32,
> so presumably the intent was to change both. Is this in agreement with
> what it means on glibc or elsewhere?

glibc uses __WORDSIZE == 64 to differentiate x86-64 from x86-64-32, so
it should be 32 for x32.

However, arch/x32/bits/user.h looks written as if define __WORDSIZE to
64 changes the width of long to 64.  I think struct user_regs_struct
needs to have unsigned long long members on x32.  (It's what glibc uses
for both x86-64 and x86-64-32.)  Likewise a most of the members of
struct user.

Thanks,
Florian

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