From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Mark Rutland <mark.rutland@arm.com>,
Keno Fischer <keno@juliacomputing.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm list <kvm@vger.kernel.org>,
Gabriel Krisman Bertazi <krisman@collabora.com>
Subject: Re: [patch V3 01/13] entry: Provide generic syscall entry functionality
Date: Sat, 18 Jul 2020 16:16:26 +0200 [thread overview]
Message-ID: <875zakq56t.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CALCETrXz_vEySQJ=f3MTPG9XjZS7U0P-diJE9j_+0KRa_Kie=Q@mail.gmail.com>
Andy Lutomirski <luto@kernel.org> writes:
> On Fri, Jul 17, 2020 at 12:29 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>> The alternative is to play nasty games with TIF_IA32, TIF_ADDR32 and
>> TIF_X32 to free up bits for 32bit and make the flags field 64 bit on 64
>> bit kernels, but I prefer to do the above seperation.
>
> I'm all for cleaning it up, but I don't think any nasty games would be
> needed regardless. IMO at least the following flags are nonsense and
> don't belong in TIF_anything at all:
>
> TIF_IA32, TIF_X32: can probably be deleted. Someone would just need
> to finish the work.
> TIF_ADDR32: also probably removable, but I'm less confident.
> TIF_FORCED_TF: This is purely a ptrace artifact and could easily go
> somewhere else entirely.
>
> So getting those five bits back would be straightforward.
>
> FWIW, TIF_USER_RETURN_NOTIFY is a bit of an odd duck: it's an
> entry/exit word *and* a context switch word. The latter is because
> it's logically a per-cpu flag, not a per-task flag, and the context
> switch code moves it around so it's always set on the running task.
Gah, I missed the context switch thing of that. That stuff is hideous.
Thanks,
tglx
next prev parent reply other threads:[~2020-07-18 14:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 18:22 [patch V3 00/13] entry, x86, kvm: Generic entry/exit functionality for host and guest Thomas Gleixner
2020-07-16 18:22 ` [patch V3 01/13] entry: Provide generic syscall entry functionality Thomas Gleixner
2020-07-16 20:52 ` Kees Cook
2020-07-16 21:55 ` Thomas Gleixner
2020-07-17 17:49 ` Kees Cook
2020-07-17 19:29 ` Thomas Gleixner
2020-07-17 21:56 ` Andy Lutomirski
2020-07-18 14:16 ` Thomas Gleixner [this message]
2020-07-18 14:41 ` Andy Lutomirski
2020-07-19 10:17 ` Thomas Gleixner
2020-07-19 10:17 ` Thomas Gleixner
2020-07-19 10:17 ` Thomas Gleixner
2020-07-19 15:25 ` Andy Lutomirski
2020-07-20 6:50 ` Thomas Gleixner
2020-07-27 22:28 ` Andy Lutomirski
2020-07-16 18:22 ` [patch V3 02/13] entry: Provide generic syscall exit function Thomas Gleixner
2020-07-16 20:55 ` Kees Cook
2020-07-16 21:28 ` Thomas Gleixner
2020-07-16 18:22 ` [patch V3 03/13] entry: Provide generic interrupt entry/exit code Thomas Gleixner
2020-07-16 18:22 ` [patch V3 04/13] entry: Provide infrastructure for work before exiting to guest mode Thomas Gleixner
2020-07-16 18:22 ` [patch V3 05/13] x86/entry: Consolidate check_user_regs() Thomas Gleixner
2020-07-16 20:56 ` Kees Cook
2020-07-16 18:22 ` [patch V3 06/13] x86/entry: Consolidate 32/64 bit syscall entry Thomas Gleixner
2020-07-16 18:22 ` [patch V3 07/13] x86/ptrace: Provide pt_regs helpers for entry/exit Thomas Gleixner
2020-07-16 20:57 ` Kees Cook
2020-07-16 18:22 ` [patch V3 08/13] x86/entry: Use generic syscall entry function Thomas Gleixner
2020-07-16 21:13 ` Kees Cook
2020-07-16 21:33 ` Thomas Gleixner
2020-07-16 18:22 ` [patch V3 09/13] x86/entry: Use generic syscall exit functionality Thomas Gleixner
2020-07-16 18:22 ` [patch V3 10/13] x86/entry: Cleanup idtentry_entry/exit_user Thomas Gleixner
2020-07-16 18:22 ` [patch V3 11/13] x86/entry: Use generic interrupt entry/exit code Thomas Gleixner
2020-07-16 18:22 ` [patch V3 12/13] x86/entry: Cleanup idtentry_enter/exit Thomas Gleixner
2020-07-16 18:22 ` [patch V3 13/13] x86/kvm: Use generic exit to guest work function Thomas Gleixner
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