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[60.240.189.67]) by smtp.gmail.com with ESMTPSA id y1-v6sm688097pfy.89.2018.10.02.23.09.13 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 02 Oct 2018 23:09:16 -0700 (PDT) Date: Wed, 3 Oct 2018 16:09:11 +1000 From: Nicholas Piggin To: Christophe LEROY Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , aneesh.kumar@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC PATCH v3 5/7] powerpc: 'current_set' is now a table of task_struct pointers Message-ID: <20181003160911.18fb0c60@roar.ozlabs.ibm.com> In-Reply-To: <0336ff43-55ac-067b-23a9-4cb4b2fd38f3@c-s.fr> References: <20181003154101.0b46956d@roar.ozlabs.ibm.com> <0336ff43-55ac-067b-23a9-4cb4b2fd38f3@c-s.fr> X-Mailer: Claws Mail 3.17.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 3 Oct 2018 08:00:43 +0200 Christophe LEROY wrote: > Le 03/10/2018 =C3=A0 07:41, Nicholas Piggin a =C3=A9crit=C2=A0: > > On Mon, 1 Oct 2018 12:30:27 +0000 (UTC) > > Christophe Leroy wrote: > > =20 > >> The table of pointers 'current_set' has been used for retrieving > >> the stack and current. They used to be thread_info pointers as > >> they were pointing to the stack and current was taken from the > >> 'task' field of the thread_info. > >> > >> Now, the pointers of 'current_set' table are now both pointers > >> to task_struct and pointers to thread_info. > >> > >> As they are used to get current, and the stack pointer is > >> retrieved from current's stack field, this patch changes > >> their type to task_struct, and renames secondary_ti to > >> secondary_current. =20 > >=20 > > I'm not sure if current_set is actually needed is it? Because > > 64-bit already initializes paca->ksave / PACAKSAVE. That might > > be a cleanup to do after your series. =20 >=20 > head_64.S contains: >=20 > __secondary_start: > /* Set thread priority to MEDIUM */ > HMT_MEDIUM >=20 > /* Initialize the kernel stack */ > LOAD_REG_ADDR(r3, current_set) > sldi r28,r24,3 /* get current_set[cpu#] */ > ldx r14,r3,r28 > addi r14,r14,THREAD_SIZE-STACK_FRAME_OVERHEAD > std r14,PACAKSAVE(r13) Right, I don't *think* that's needed because boot CPU should already have set PACAKSAVE before starting secondaries here. ld r14,PACAKSAVE should have the same result I think. But never mind that for your series, just something I saw that could be cleaned up. Thanks, Nick