[U-Boot] [PATCH V4 05/11] ARM: OMAP: Change set_pl310_ctrl_reg to be generic

[Nishanth Menon]

On 03/05/2015 08:00 AM, Matt Porter wrote:
> On Tue, Mar 03, 2015 at 04:26:22PM -0600, Nishanth Menon wrote:
>> set_pl310_ctrl_reg does use the Secure Monitor Call (SMC) to setup
>> PL310 control register, however, that is something that is generic
>> enough to be used for OMAP5 generation of processors as well. The only
>> difference being the service being invoked for the function.
>>
>> So, convert the service to a macro and use a generic name (same as
>> that used in Linux for some consistency). While at that, also add a
>> data barrier which is necessary as per recommendation.
>>
>> While at this, switch over to smc #0 instead of handcoded assembly.
>> To ensure gcc compatibility, steal the strategy used by Linux kernel
>> for sec extension builds (NOTE: we no longer use '-march=armv5' as the
>> legacy comment claims).
> 
> Hi Nishanth,
> 
> I applied this series with fuzz and fixed a minor conflict on master. I
> ran into a build issue for omap3 beagle with the sec extension scheme on
> the gcc version 4.7.4 (Ubuntu/Linaro 4.7.4-2ubuntu1) toolchain:
> 
>  arm-linux-gnueabi-gcc
> -Wp,-MD,arch/arm/cpu/armv7/omap3/.lowlevel_init.o.d  -nostdinc -isystem
> /usr/lib/gcc-cross/arm-linux-gnueabi/4.7/include -Iinclude  -I../include
> -I../arch/arm/include -include ../include/linux/kconfig.h -D__KERNEL__
> -D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0x80100000 -D__ASSEMBLY__ -g
> -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux
> -mword-relocations -march=armv7-a -mno-unaligned-access
> -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float
> -pipe   -c -o arch/arm/cpu/armv7/omap3/lowlevel_init.o
> ../arch/arm/cpu/armv7/omap3/lowlevel_init.S
> 
> ../arch/arm/cpu/armv7/omap-common/lowlevel_init.S: Assembler messages:
> ../arch/arm/cpu/armv7/omap-common/lowlevel_init.S:34: Error: selected
> processor does not support ARM mode `smc #0'
> 
> I've worked around this for the moment by placing an explicit
> .arch_extension sec in lowlevel_init.S but hopefully you have some
> thoughts on why those flags don't seem to be picked up. I'll continue
> to take a look at it in the meantime.
> 


Uggh.. this is weird. I had considered ".arch_extension sec in
lowlevel_init.S"

> +plus_sec := $(call as-instr,.arch_extension sec,+sec)
> +AFLAGS_lowlevel_init.o       :=-Wa,-march=armv7-a$(plus_sec)

seems to be what we have in kernel and seems to do the job for me on
$ arm-linux-gnueabi-gcc --version
arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3

$ git clean -fdx; make omap3_beagle_defconfig;
make V=1 arch/arm/cpu/armv7/omap-common/lowlevel_init.o

with gcc 4.6:
arm-linux-gnueabi-gcc
-Wp,-MD,arch/arm/cpu/armv7/omap-common/.lowlevel_init.o.d  -nostdinc
-isystem /usr/lib/gcc/arm-linux-gnueabi/4.6/include -Iinclude
-I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__
-D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0x80100000  -D__ASSEMBLY__ -g
-D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux
-mword-relocations  -march=armv7-a  -mno-unaligned-access
-ffunction-sections -fdata-sections -fno-common -ffixed-r9
-msoft-float  -pipe   -Wa,-march=armv7-a+sec   -c -o
arch/arm/cpu/armv7/omap-common/lowlevel_init.o
arch/arm/cpu/armv7/omap-common/lowlevel_init.S


with gcc 4.7:
arm-linux-gnueabi-gcc
-Wp,-MD,arch/arm/cpu/armv7/omap-common/.lowlevel_init.o.d  -nostdinc
-isystem /usr/lib/gcc-cross/arm-linux-gnueabi/4.7/include -Iinclude
-I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__
-D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0x80100000  -D__ASSEMBLY__ -g
-D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux
-mword-relocations  -march=armv7-a  -mno-unaligned-access
-ffunction-sections -fdata-sections -fno-common -ffixed-r9
-msoft-float  -pipe  -Wa,-march=armv7-a   -c -o
arch/arm/cpu/armv7/omap-common/lowlevel_init.o
arch/arm/cpu/armv7/omap-common/lowlevel_init.S
arch/arm/cpu/armv7/omap-common/lowlevel_init.S: Assembler messages:
arch/arm/cpu/armv7/omap-common/lowlevel_init.S:34: Error: selected
processor does not support ARM mode `smc #0'
make[1]: *** [arch/arm/cpu/armv7/omap-common/lowlevel_init.o] Error 1
make: *** [arch/arm/cpu/armv7/omap-common/lowlevel_init.o] Error 2

I thought I stole the exact code from kernel, but as you can probably
see -march=armv7-a+sec was generated for gcc 4.6 but -march=armv7-a
without +sec for gcc 4.7!

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/Makefile#n44

It will be nice to have a solution that works on gcc 4.4 and above..
if we want to ignore gcc 4.4, then we can embed ".arch_extension sec
in lowlevel_init.S"

https://gcc.gnu.org/ml/gcc-help/2012-07/msg00181.html


any suggestions?

[...]
-- 
Regards,
Nishanth Menon