Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Content-Type: text/plain;
        charset=us-ascii
Mime-Version: 1.0 (1.0)
Subject: Re: [PATCH v2 13/20] x86/asm/64: Pass sp0 directly to load_sp0()
From:   Andy Lutomirski <luto@amacapital.net>
In-Reply-To: <20171102094813.idw77gu2rarcu4zq@gmail.com>
Date:   Thu, 2 Nov 2017 11:32:38 +0100
Cc:     Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
        Borislav Petkov <bpetkov@suse.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Brian Gerst <brgerst@gmail.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <429FD204-476B-4F5B-B007-A444F6562E79@amacapital.net>
References: <cover.1509609304.git.luto@kernel.org> <2655d8b42ed940aa384fe18ee1129bbbcf730a08.1509609304.git.luto@kernel.org> <20171102094813.idw77gu2rarcu4zq@gmail.com>
To:     Ingo Molnar <mingo@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Nov 2, 2017, at 10:48 AM, Ingo Molnar <mingo@kernel.org> wrote:
>=20
>=20
> * Andy Lutomirski <luto@kernel.org> wrote:
>=20
>> load_sp0() had an odd signature:
>>=20
>> void load_sp0(struct tss_struct *tss, struct thread_struct *thread);
>>=20
>> Simplify it to:
>>=20
>> void load_sp0(unsigned long sp0);
>=20
> I also added this to the changelog:
>=20
>> Also simplify a few get_cpu()/put_cpu() sequences to
>> preempt_disable()/preempt_enable().
>=20
> Plus:
>=20
>> --- a/arch/x86/kernel/cpu/common.c
>> +++ b/arch/x86/kernel/cpu/common.c
>> @@ -1572,7 +1572,7 @@ void cpu_init(void)
>>    initialize_tlbstate_and_flush();
>>    enter_lazy_tlb(&init_mm, me);
>>=20
>> -    load_sp0(t, &current->thread);
>> +    load_sp0(current->thread.sp0);
>>    set_tss_desc(cpu, t);
>>    load_TR_desc();
>>    load_mm_ldt(&init_mm);
>> @@ -1627,7 +1627,7 @@ void cpu_init(void)
>>    initialize_tlbstate_and_flush();
>>    enter_lazy_tlb(&init_mm, curr);
>>=20
>> -    load_sp0(t, thread);
>> +    load_sp0(thread->sp0);
>>    set_tss_desc(cpu, t);
>>    load_TR_desc();
>>    load_mm_ldt(&init_mm);
>=20
> In the 32-bit path this was the last use of 'thread', making the local var=
iable=20
> unused - I removed it.
>=20
> Just curious: did you build/boot-test 32-bit kernels, or should we conside=
r it=20
> mostly untested?

I tested it in an earlier version, but I'm away from my real computer, so I h=
aven't tested as well as I should.  It should be run through at least the se=
lftests on 32-bit, 64-bit, and Xen PV.

>=20
> Thanks,
>=20
>    Ingo

From 1582947599188798930@xxx Thu Nov 02 09:54:29 +0000 2017
X-GM-THRID: 1582940507843427928
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread