On Mon, Sep 21, 2020 at 05:12:27PM +0800, Huacai Chen wrote: > Loongson-3's COP2 is Multi-Media coprocessor, it is disabled in kernel > mode by default. However, gslq/gssq (16-bytes load/store instructions) > overrides the instruction format of lwc2/swc2. If we wan't to use gslq/ > gssq for optimization in kernel, we should enable COP2 usage in kernel. > > Please pay attention that in this patch we only enable COP2 in kernel, > which means it will lose ST0_CU2 when a process go to user space (try > to use COP2 in user space will trigger an exception and then grab COP2, > which is similar to FPU). And as a result, we need to modify the context > switching code because the new scheduled process doesn't contain ST0_CU2 > in its THERAD_STATUS probably. > > For zboot, we disable gslq/gssq be generated by toolchain. > > Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx> > --- > V3: Stop using ST0_MM and use ST0_CU2 instead (Thank Thomas and Maciej). > V4: Adopt Thomas's suggestion to improve coding style. > V5: Use ST0_KERNEL_CUMASK in all possible places to avoid #ifdefs. > V6: Modify switch_to() and don't touch r4k_switch.S. > V7: For zboot, disable gslq/gssq be generated by toolchain. > > arch/mips/boot/compressed/Makefile | 5 +++++ > arch/mips/include/asm/mipsregs.h | 7 +++++++ > arch/mips/include/asm/stackframe.h | 6 +++--- > arch/mips/kernel/head.S | 2 +- > arch/mips/kernel/process.c | 4 ++-- > arch/mips/kernel/traps.c | 2 +- > 6 files changed, 19 insertions(+), 7 deletions(-) > > diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile > index 9a9ba77..2c491c1 100644 > --- a/arch/mips/boot/compressed/Makefile > +++ b/arch/mips/boot/compressed/Makefile > @@ -22,6 +22,11 @@ KBUILD_CFLAGS := $(filter-out -pg, $(KBUILD_CFLAGS)) > > KBUILD_CFLAGS := $(filter-out -fstack-protector, $(KBUILD_CFLAGS)) > > +# Disable lq/sq in zboot > +ifdef CONFIG_CPU_LOONGSON64 > +KBUILD_CFLAGS := $(filter-out -march=loongson3a, $(KBUILD_CFLAGS)) -march=mips64r2 > +endif > + thanks for doing this, I'm going to apply this later. This remind of another question, what about loongson2ef ? I'm getting kbuild failure because of enabled loongson-mmi mails. Are we are missing something like cflags-y += $(call cc-option,-mno-loongson-mmi) in Platform file ? Who is taking care of loongson2ef ? Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]
