From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1f6BJs-0004M8-7J for barebox@lists.infradead.org; Wed, 11 Apr 2018 08:41:33 +0000 Date: Wed, 11 Apr 2018 10:41:20 +0200 From: Sascha Hauer Message-ID: <20180411084120.cxoyjrvp7f52aus2@pengutronix.de> References: <20180326192025.28809-1-l.stach@pengutronix.de> <20180326192025.28809-4-l.stach@pengutronix.de> <20180405075402.gbplqqwoubu7cqpg@pengutronix.de> <1523357612.4981.5.camel@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1523357612.4981.5.camel@pengutronix.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: quoted-printable Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH v3 04/10] ARM: add file for HYP mode related setup To: Lucas Stach Cc: barebox@lists.infradead.org On Tue, Apr 10, 2018 at 12:53:32PM +0200, Lucas Stach wrote: > Am Donnerstag, den 05.04.2018, 09:54 +0200 schrieb Sascha Hauer: > > On Mon, Mar 26, 2018 at 09:20:19PM +0200, Lucas Stach wrote: > > > This adds routines to add hyp mode vectors and switch back to HYP > > > mode from SVC. This is needed in both the PBL and Barebox proper. > > > = > > > > > Signed-off-by: Lucas Stach > > > > > Tested-by: Roland Hieber > > > --- > > > v3: > > > - fix whitespace > > > - use __BARE_INIT > > > --- > > > =A0arch/arm/cpu/Makefile=A0=A0=A0=A0=A0=A0=A0=A0=A0|=A0=A0=A04 ++ > > > =A0arch/arm/cpu/hyp.S=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0| 116 ++++++= ++++++++++++++++++++++++++++++++++++ > > > =A0arch/arm/cpu/sm_as.S=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0|=A0=A011 ---- > > > =A0arch/arm/include/asm/secure.h |=A0=A0=A08 +++ > > > =A04 files changed, 128 insertions(+), 11 deletions(-) > > > =A0create mode 100644 arch/arm/cpu/hyp.S > > > = > > > diff --git a/arch/arm/cpu/Makefile b/arch/arm/cpu/Makefile > > > index 13fe12c31f6f..f86dff975bb4 100644 > > > --- a/arch/arm/cpu/Makefile > > > +++ b/arch/arm/cpu/Makefile > > > @@ -9,6 +9,10 @@ obj-$(CONFIG_ARM_EXCEPTIONS) +=3D exceptions.o > > > =A0obj-$(CONFIG_MMU) +=3D mmu.o mmu-early.o > > > =A0pbl-$(CONFIG_MMU) +=3D mmu-early.o > > > =A0lwl-y +=3D lowlevel.o > > > +obj-y +=3D hyp.o > > > +AFLAGS_hyp.o :=3D-Wa,-march=3Darmv7-a -Wa,-mcpu=3Dall > > > +pbl-y +=3D hyp.o > > > +AFLAGS_pbl-hyp.o :=3D-Wa,-march=3Darmv7-a -Wa,-mcpu=3Dall > > > =A0endif > > > =A0 > > > =A0obj-$(CONFIG_ARM_EXCEPTIONS) +=3D interrupts.o > > > diff --git a/arch/arm/cpu/hyp.S b/arch/arm/cpu/hyp.S > > > new file mode 100644 > > > index 000000000000..1314b56eab25 > > > --- /dev/null > > > +++ b/arch/arm/cpu/hyp.S > > > @@ -0,0 +1,116 @@ > > > +#include > > > +#include > > > +#include > > > +#include > > > + > > > +.arch_extension sec > > > +.arch_extension virt > > > + > > > +__BARE_INIT > > > + > > > +.data > > > > > + .align=A0=A02 > > > +ENTRY(__boot_cpu_mode) > > > > > + .long=A0=A0=A00 > > > +.text > > > + > > > +ENTRY(__hyp_install) > > > > > > > + mrs r12, cpsr > > > > > > > + and r12, r12, #MODE_MASK > > > + > > > > > + @ Save the initial CPU state > > > > > > > + adr r0, .L__boot_cpu_mode_offset > > > > > > > + ldr r1, [r0] > > > + str r12, [r0, r1] > > = > > Naa, this won't work. You save the cpsr value in __boot_cpu_mode, but > > this variable exists both in PBL and regular barebox, __hyp_install > > is called multiple times and cpsr is modified right after saving it. > = > It does. ;) > = > I guess its non-obvious from the code flow, but what we do is to drop > down to SVC in the PBL, then jump back to HYP before starting barebox > proper and the dropping down to SVC again on barebox entry. > All in all this is less-than-pretty, but IMHO it's the lesser evil than > trying to implement some communication channel from PBL to barebox > proper to pass information like this. > = > So I guess this code needs some more comments... Yep ;) Sascha -- = Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox