On Thu, Mar 05, 2015 at 11:49:05AM -0600, Nishanth Menon wrote:
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"
Yeah, no worries, I'm not suggesting that. Just a temporary workaround.
+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
right
$ 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
I also succeed here..and on a gcc 4.8.2 toolchain
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!
Yeah, so I played a bit with the low-level checks and noted the following results.
gcc version 4.7.4 (Ubuntu/Linaro 4.7.4-2ubuntu1):
$ printf "%b\n" ".arch_extension sec" | arm-linux-gnueabi-gcc -c -x assembler -; echo $? {standard input}: Assembler messages: {standard input}:1: Error: architectural extension `sec' is not allowed for the current base architecture 1
gcc version 4.8.2 (Ubuntu/Linaro 4.8.2-16ubuntu4)
$ printf "%b\n" ".arch_extension sec" | arm-linux-gnueabihf-gcc -c -x assembler -; echo $? 0
My 4.7.4 toolchain's gas does support -march=armv7-a+sec however I need to pass that architecture in specifically to make it pass:
$ printf "%b\n" ".arch_extension sec" | arm-linux-gnueabi-gcc -Wa,-march=armv7-a+sec -c -x assembler -; echo $? 0
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/ar...
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?
Not sure of the best approach here. It seems if the actual check engages the -march option for gas (on an omap build) we should build for any of them. That's a bit hacky though. But it's just as easy to just add the .arch_extension sec as you suggest and we have to quit supporting gcc 4.4 in either case AFAICT.
-Matt