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From: Oleg Nesterov <oleg@redhat.com>
To: Brian Gerst <brgerst@gmail.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH] x86: Remove force_iret()
Date: Fri, 20 Dec 2019 20:35:44 +0100	[thread overview]
Message-ID: <20191220193543.GD13464@redhat.com> (raw)
In-Reply-To: <20191219115812.102620-1-brgerst@gmail.com>

On 12/19, Brian Gerst wrote:
>
> force_iret() was originally intended to prevent the return to user mode with
> the SYSRET or SYSEXIT instructions, in cases where the register state could
> have been changed to be incompatible with those instructions.  The entry code
> has been significantly reworked since then, and register state is validated
> before SYSRET or SYSEXIT are used.  force_iret() no longer serves its original
> purpose and can be eliminated.

Plus iiuc today force_iret() == set_thread_flag(TIF_NOTIFY_RESUME) simply has
no effect on asm paths.

Acked-by: Oleg Nesterov <oleg@redhat.com>


  parent reply	other threads:[~2019-12-20 19:36 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-19 11:58 [PATCH] x86: Remove force_iret() Brian Gerst
2019-12-20  1:49 ` Andy Lutomirski
2019-12-20  3:48   ` Brian Gerst
2019-12-20 10:10     ` David Laight
2019-12-20 10:30       ` Andy Lutomirski
2019-12-20 10:59         ` David Laight
2019-12-20 21:20           ` Andy Lutomirski
2019-12-20 12:18       ` Brian Gerst
2019-12-20 12:35         ` David Laight
2019-12-20 19:35 ` Oleg Nesterov [this message]
2020-01-08 20:30 ` [tip: x86/asm] " tip-bot2 for Brian Gerst

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