From: Ingo Molnar <mingo@kernel.org>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com,
sfr@canb.auug.org.au, akpm@linux-foundation.org,
tglx@linutronix.de, mingo@elte.hu, hpa@zytor.com,
peterz@infradead.org, linux-next@vger.kernel.org, deller@gmx.de
Subject: Re: [PATCH] [v3] x86, pkeys: fix siginfo ABI breakage from new field
Date: Tue, 1 Mar 2016 09:09:04 +0100 [thread overview]
Message-ID: <20160301080904.GA9644@gmail.com> (raw)
In-Reply-To: <20160301074052.GA7201@gmail.com>
* Ingo Molnar <mingo@kernel.org> wrote:
> > I also shouldn't have been using a u64 in a userspace API to begin with.
>
> Well, it's __u64 that we use in UAPIs, and they can be used just fine, as long
> as the structure's field alignments is managed explicitly, i.e. there's no
> automatic alignment padding done by the compiler.
Btw., what we should not have used in a modern user ABI are variable size
pointers:
struct {
void __user *_lower;
void __user *_upper;
} _addr_bnd;
we should have used constant size structure elements for that, such as __u64.
Had we done that, the pkeys change would not have been a problem either.
Is it too late to change that, is there any si_code=SEGV_BNDERR usage in
user-space?
Thanks,
Ingo
next prev parent reply other threads:[~2016-03-01 8:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 22:17 [PATCH] [v3] x86, pkeys: fix siginfo ABI breakage from new field Dave Hansen
2016-02-29 22:33 ` Stephen Rothwell
2016-03-01 7:40 ` Ingo Molnar
2016-03-01 8:09 ` Ingo Molnar [this message]
2016-03-01 12:48 ` Dave Hansen
2016-03-01 9:39 ` Ingo Molnar
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