Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 30 Jun 2020 11:45:55 -0400 (EDT)
From:   Nicolas Pitre <nico@fluxnic.net>
To:     Al Viro <viro@zeniv.linux.org.uk>
cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        David Howells <dhowells@redhat.com>
Subject: Re: [RFC][PATCHES] converting FDPIC coredumps to regsets
In-Reply-To: <20200630043641.GD2786714@ZenIV.linux.org.uk>
Message-ID: <nycvar.YSQ.7.77.849.2006301141110.1785@knanqh.ubzr>
References: <20200630043641.GD2786714@ZenIV.linux.org.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, 30 Jun 2020, Al Viro wrote:

> 	The obvious solution is to introduce struct elf_prstatus_fdpic
> and use that in binfmt_elf_fdpic.c, taking these fields out of the
> normal struct elf_prstatus.  Unfortunately, the damn thing is defined in
> include/uapi/linux/elfcore.h, so nominally it's a part of userland ABI.
> However, not a single userland program actually includes linux/elfcore.h.
> The reason is that the definition in there uses elf_gregset_t as a member,
> and _that_ is not defined anywhere in the exported headers.  It is defined
> in (libc) sys/procfs.h, but the same file defines struct elf_prstatus
> as well.  So if you try to include linux/elfcore.h without having already
> pulled sys/procfs.h, it'll break on incomplete type of a member.  And if
> you have pulled sys/procfs.h, it'll break on redefining a structure.
> IOW, it's not usable and it never had been; as the matter of fact,
> that's the reason sys/procfs.h had been introduced back in 1996.

Huh! That's convenient alright.

Acked-by: Nicolas Pitre <nico@fluxnic.net>


Nicolas