From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?0JjQstCw0LnQu9C+INCU0LjQvNC40YLRgNC+0LI=?= Subject: Re: [PATCH v2 1/2] ARM: OMAP: Add secure function omap_smc3() which calling instruction smc #1 Date: Thu, 11 Jul 2013 22:43:59 +0300 (EEST) Message-ID: <531356997.66774.1373571839852.JavaMail.apache@mail81.abv.bg> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Dave Martin Cc: pali.rohar@gmail.com, linux-kernel@vger.kernel.org, tony@atomide.com, aaro.koskinen@iki.fi, nm@ti.com, linux@arm.linux.org.uk, pdeschrijver@nvidia.com, santosh.shilimkar@ti.com, pavel@ucw.cz, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-omap@vger.kernel.org =20 >-------- =D0=9E=D1=80=D0=B8=D0=B3=D0=B8=D0=BD=D0=B0=D0=BB=D0=BD=D0=BE= =D0=BF=D0=B8=D1=81=D0=BC=D0=BE -------- >=D0=9E=D1=82: Dave Martin=20 >=D0=9E=D1=82=D0=BD=D0=BE=D1=81=D0=BD=D0=BE: Re: [PATCH v2 1/2] ARM: O= MAP: Add secure function omap_smc3() which calling instruction smc #1 >=D0=94=D0=BE: Pali Roh=C3=A1r=20 >=D0=98=D0=B7=D0=BF=D1=80=D0=B0=D1=82=D0=B5=D0=BD=D0=BE =D0=BD=D0=B0: = =D0=A1=D1=80=D1=8F=D0=B4=D0=B0, 2013, =D0=AE=D0=BB=D0=B8 10 20:45:26 EE= ST > > >On Wed, Jul 10, 2013 at 02:59:04PM +0200, Pali Roh=C3=A1r wrote: >> Other secure functions omap_smc1() and omap_smc2() calling instruct= ion smc #0 >> but Nokia RX-51 board needs to call smc #1 for PPA access. >>=20 >> Signed-off-by: Ivaylo Dimitrov=20 >> Signed-off-by: Pali Roh=C3=A1r=20 >> --- >> arch/arm/mach-omap2/omap-secure.h | 1 + >> arch/arm/mach-omap2/omap-smc.S | 22 +++++++++++++++++++++- >> 2 files changed, 22 insertions(+), 1 deletion(-) >>=20 >> diff --git a/arch/arm/mach-omap2/omap-secure.h b/arch/arm/mach-omap= 2/omap-secure.h >> index 0e72917..c4586f4 100644 >> --- a/arch/arm/mach-omap2/omap-secure.h >> +++ b/arch/arm/mach-omap2/omap-secure.h >> @@ -51,6 +51,7 @@ >> extern u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs, >> u32 arg1, u32 arg2, u32 arg3, u32 arg4); >> extern u32 omap_smc2(u32 id, u32 falg, u32 pargs); >> +extern u32 omap_smc3(u32 id, u32 process, u32 flag, u32 pargs); >> extern phys_addr_t omap_secure_ram_mempool_base(void); >> extern int omap_secure_ram_reserve_memblock(void); >> =20 >> diff --git a/arch/arm/mach-omap2/omap-smc.S b/arch/arm/mach-omap2/o= map-smc.S >> index f6441c1..5c02b8d 100644 >> --- a/arch/arm/mach-omap2/omap-smc.S >> +++ b/arch/arm/mach-omap2/omap-smc.S >> @@ -1,9 +1,11 @@ >> /* >> - * OMAP44xx secure APIs file. >> + * OMAP34xx and OMAP44xx secure APIs file. >> * >> * Copyright (C) 2010 Texas Instruments, Inc. >> * Written by Santosh Shilimkar=20 >> * >> + * Copyright (C) 2012 Ivaylo Dimitrov=20 >> + * Copyright (C) 2013 Pali Roh=C3=A1r=20 >> * >> * This program is free software,you can redistribute it and/or mo= dify >> * it under the terms of the GNU General Public License version 2 = as >> @@ -54,6 +56,24 @@ ENTRY(omap_smc2) >> ldmfd sp!, {r4-r12, pc} >> ENDPROC(omap_smc2) >> =20 >> +/** >> + * u32 omap_smc3(u32 service_id, u32 process_id, u32 flag, u32 par= gs) >> + * Low level common routine for secure HAL and PPA APIs via smc #1 >> + * r0 - @service_id: Secure Service ID >> + * r1 - @process_id: Process ID >> + * r2 - @flag: Flag to indicate the criticality of operation >> + * r3 - @pargs: Physical address of parameter list >> + */ >> +ENTRY(omap_smc3) >> + stmfd sp!, {r4-r12, lr} > >You don't need to save/restore r12. The ABI allows it to be clobbere= d >across function calls. > >> + mov r12, r0 @ Copy the secure service ID >> + mov r6, #0xff @ Indicate new Task call >> + dsb >> + dmb > >dsb synchronises a superset of what dmb synchronises, so the dmb here= is >not useful. > >In any case, any code calling this must flush the region addressed by >r3 beforehand anyway, which will include a dsb as part of its semanti= cs >-- this is how you call it from rx51_secure_dispatcher(). > >So I think the dsb may not be needed here (?) > >Cheers >---Dave > > Could be, but I wonder why almost all the kernel code(I am aware of) th= at uses SMC and is written by TI, is storing r12 and is using both DSB = and DMB. See arch/arm/mach-omap2/sleep34xx.S or arch/arm/mach-omap2/oma= p-smc.S for examples. I'd rather play it safe and leave it that way, un= less someone confirms the other code using SMC has extra DSB/DMB instru= ctions too. I wouldn't risk passing invalid/stale data to the Secure Mo= nitor to just save 8 bytes and barriers in a performance non-critical c= ode which will be called only a couple of times during the boot-up proc= ess. r12 save/restore is a legacy from omap_smc2 in omap-smc.S, so I gu= ess it can go away without much of a trouble.