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From: Florian Weimer <fw@deneb.enyo.de>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>
Subject: Re: [PATCH] Add SYSCALL_LONG/SYSCALL_ULONG to pass long to syscall
 [BZ #25810]
References: <20200410212249.3529885-1-hjl.tools@gmail.com>
 <87k12m9w9n.fsf@mid.deneb.enyo.de>
 <CAMe9rOqP_s6nUnxZOphja3HXLcvjBd7bQ0wHxijLYLFQBO3trw@mail.gmail.com>
Date: Sat, 11 Apr 2020 16:45:24 +0200
In-Reply-To: <CAMe9rOqP_s6nUnxZOphja3HXLcvjBd7bQ0wHxijLYLFQBO3trw@mail.gmail.com>
 (H. J. Lu's message of "Sat, 11 Apr 2020 06:26:08 -0700")
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* H. J. Lu:

> On Sat, Apr 11, 2020 at 3:01 AM Florian Weimer <fw@deneb.enyo.de> wrote:
>>
>> * H. J. Lu via Libc-alpha:
>>
>> > For inline syscalls, SYSCALL_LONG and SYSCALL_ULONG are introduced as
>> > wrappers for long and unsigned long arguments.
>>
>> Do the arguments have the correct types?  Then I think you can do the
>
> Yes, they have correct types.  But it is not the problem.  Take this example:
>
> int munmap(void *addr, size_t length);
>
> The type of length is unsigned int (size_t) for x32 and is unsigned long
> (64bit) in kernel.  We have no way to know the type which kernel expects.

Is it possible to extend all 32-bit arguments?  Ot is this incorrect
for negative int arguments, which must not have their upper bits set?