Re: [kvm-unit-tests PATCH v3 2/2] powerpc: select endianness

[Laurent Vivier <lvivier@redhat.com>]

On 29/02/2016 20:44, Andrew Jones wrote:
> On Mon, Feb 29, 2016 at 06:49:06PM +0100, Laurent Vivier wrote:
>> This patch allows to build tests for ppc64 little endian target
>> (ppc64le) on big and little endian hosts.
>>
>> We add a new parameter to configure to select the endianness of the
>> tests (--endian=little or --endian=big).
>>
>> I have built and tested big and little endian tests on a little
>> endian host, a big endian host, with kvm_hv and kvm_pr, and on
>> x86_64 with ppc64 as a TCG target.
>>
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>> ---
>>  configure                 | 11 +++++++++++
>>  lib/powerpc/asm/ppc_asm.h | 19 +++++++++++++++++++
>>  lib/ppc64/asm/io.h        |  8 ++++++++
>>  powerpc/Makefile.common   |  3 ++-
>>  powerpc/Makefile.ppc64    |  9 +++++++--
>>  powerpc/cstart64.S        | 20 ++++++++++++++++----
>>  6 files changed, 63 insertions(+), 7 deletions(-)
>>
>> diff --git a/configure b/configure
>> index a685cca..90e39d4 100755
>> --- a/configure
>> +++ b/configure
>> @@ -10,6 +10,7 @@ ar=ar
>>  arch=`uname -m | sed -e 's/i.86/i386/;s/arm.*/arm/;s/ppc64.*/ppc64/'`
>>  host=$arch
>>  cross_prefix>> +endian=""
>>  
>>  usage() {
>>      cat <<-EOF
>> @@ -23,6 +24,7 @@ usage() {
>>  	    --ld=LD		   ld linker to use ($ld)
>>  	    --prefix=PREFIX        where to install things ($prefix)
>>  	    --kerneldir=DIR        kernel build directory for kvm.h ($kerneldir)
>> +	    --endian=ENDIAN        endianness to compile for (little or big, ppc64 only)
>>  EOF
>>      exit 1
>>  }
>> @@ -50,6 +52,9 @@ while [[ "$1" = -* ]]; do
>>  	--cross-prefix)
>>  	    cross_prefix="$arg"
>>  	    ;;
>> +	--endian)
>> +	    endian="$arg"
>> +	    ;;
>>  	--cc)
>>  	    cc="$arg"
>>  	    ;;
>> @@ -84,6 +89,11 @@ elif [ "$arch" = "arm" ] || [ "$arch" = "arm64" ]; then
>>  elif [ "$arch" = "ppc64" ]; then
>>      testdir=powerpc
>>      firmware="$testdir/boot_rom.bin"
>> +    if [ "$endian" != "little" ] && [ "$endian" != "big" ]; then
>> +        echo "You must provide endianness (big or little)!"
>> +        usage
>> +        exit 1
> 
> redundant 'exit 1', usage() already has one in it

OK

> 
>> +    fi
>>  else
>>      testdir=$arch
>>  fi
>> @@ -139,4 +149,5 @@ AR=$cross_prefix$ar
>>  API=$api
>>  TEST_DIR=$testdir
>>  FIRMWARE=$firmware
>> +ENDIAN=$endian
>>  EOF
>> diff --git a/lib/powerpc/asm/ppc_asm.h b/lib/powerpc/asm/ppc_asm.h
>> index f63bb72..f18100e 100644
>> --- a/lib/powerpc/asm/ppc_asm.h
>> +++ b/lib/powerpc/asm/ppc_asm.h
>> @@ -11,4 +11,23 @@
>>  #define LOAD_REG_ADDR(reg,name)			\
>>  	ld	reg,name@got(r2)
>>  
>> +#if __BYTE_ORDER__ = __ORDER_BIG_ENDIAN__
>> +
>> +#define FIXUP_ENDIAN
>> +
>> +#elif __BYTE_ORDER__ = __ORDER_LITTLE_ENDIAN__
>> +
>> +#define FIXUP_ENDIAN				\
>> +	.long 0x05000048; /* bl . + 4        */ \
>> +	.long 0xa602487d; /* mflr r10        */	\
>> +	.long 0x20004a39; /* addi r10,r10,32 */	\
>> +	.long 0xa600607d; /* mfmsr r11       */	\
>> +	.long 0x01006b69; /* xori r11,r11,1  */	\
>> +	.long 0xa6035a7d; /* mtsrr0 r10	     */	\
>> +	.long 0xa6037b7d; /* mtsrr1 r11      */	\
>> +	.long 0x2400004c; /* rfid            */ \
>> +	.long 0x00000048; /* b .             */ \
>> +
>> +#endif /* __BYTE_ORDER__ */
>> +
>>  #endif /* _ASMPOWERPC_PPC_ASM_H */
>> diff --git a/lib/ppc64/asm/io.h b/lib/ppc64/asm/io.h
>> index c0801d4..4f2c31b 100644
>> --- a/lib/ppc64/asm/io.h
>> +++ b/lib/ppc64/asm/io.h
>> @@ -1,5 +1,13 @@
>>  #ifndef _ASMPPC64_IO_H_
>>  #define _ASMPPC64_IO_H_
>> +
>> +#if __BYTE_ORDER__ = __ORDER_LITTLE_ENDIAN__
>> +#define __cpu_is_be() (0)
>> +#elif __BYTE_ORDER__ = __ORDER_BIG_ENDIAN__
>>  #define __cpu_is_be() (1)
>> +#else
>> +#error Undefined byte order
>> +#endif
>> +
>>  #include <asm-generic/io.h>
>>  #endif
>> diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
>> index cc27ac8..b526668 100644
>> --- a/powerpc/Makefile.common
>> +++ b/powerpc/Makefile.common
>> @@ -11,7 +11,6 @@ all: $(TEST_DIR)/boot_rom.bin test_cases
>>  
>>  ##################################################################
>>  
>> -CFLAGS += $(arch_CFLAGS)
>>  CFLAGS += -std=gnu99
>>  CFLAGS += -ffreestanding
>>  CFLAGS += -Wextra
>> @@ -32,6 +31,7 @@ cflatobjs += lib/powerpc/setup.o
>>  cflatobjs += lib/powerpc/rtas.o
>>  
>>  FLATLIBS = $(libcflat) $(LIBFDT_archive)
>> +%.elf: CFLAGS += $(arch_CFLAGS)
>>  %.elf: LDFLAGS = $(arch_LDFLAGS) -nostdlib -pie
>>  %.elf: %.o $(FLATLIBS) powerpc/flat.lds
>>  	$(LD) $(LDFLAGS) -o $@ \
>> @@ -48,6 +48,7 @@ $(TEST_DIR)/boot_rom.bin: $(TEST_DIR)/boot_rom.elf
>>  	dd if=/dev/zero of=$@ bs%6 count=1
>>  	$(OBJCOPY) -O binary $^ >(cat - >>$@)
>>  
>> +$(TEST_DIR)/boot_rom.elf: CFLAGS = -mbig-endian
>>  $(TEST_DIR)/boot_rom.elf: $(TEST_DIR)/boot_rom.o
>>  	$(LD) -EB -nostdlib -Ttext=0x100 --entry=start --build-id=none -o $@ $<
>>  
>> diff --git a/powerpc/Makefile.ppc64 b/powerpc/Makefile.ppc64
>> index 2df44d4..3da3a83 100644
>> --- a/powerpc/Makefile.ppc64
>> +++ b/powerpc/Makefile.ppc64
>> @@ -5,8 +5,13 @@
>>  #
>>  bits = 64
>>  
>> -arch_CFLAGS = -mbig-endian
>> -arch_LDFLAGS = -EB
>> +ifeq ($(ENDIAN),little)
>> +    arch_CFLAGS = -mlittle-endian
>> +    arch_LDFLAGS = -EL
>> +else
>> +    arch_CFLAGS = -mbig-endian
>> +    arch_LDFLAGS = -EB
>> +endif
>>  
>>  cstart.o = $(TEST_DIR)/cstart64.o
>>  reloc.o  = $(TEST_DIR)/reloc64.o
>> diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
>> index 6072597..62078a4 100644
>> --- a/powerpc/cstart64.S
>> +++ b/powerpc/cstart64.S
>> @@ -16,6 +16,7 @@
>>   */
>>  .globl start
>>  start:
>> +	FIXUP_ENDIAN
>>  	/*
>>  	 * We were loaded at QEMU's kernel load address, but we're not
>>  	 * allowed to link there due to how QEMU deals with linker VMAs,
>> @@ -84,12 +85,23 @@ halt:
>>  enter_rtas:
>>  	mflr	r0
>>  	std	r0, 16(r1)
>> +
>> +	LOAD_REG_ADDR(r10, rtas_return_loc)
>> +	mtlr	r10
>>  	LOAD_REG_ADDR(r11, rtas_entry)
>>  	ld	r10, 0(r11)
>> -//FIXME: change this bctrl to an rtas-prep, rfid, rtas-return sequence
>> -	mtctr	r10
>> -	nop
>> -	bctrl
>> +
>> +	mfmsr	r11
>> +#if __BYTE_ORDER__ = __ORDER_LITTLE_ENDIAN__
>> +	xori	r11,r11,1
>> +#endif
> 
> We can avoid the #if.
> 
>  LOAD_REG_IMMEDIATE(r9, RTAS_MSR_MASK)
>  and	r11, r11, r9
> 
> Right now we'll define RTAS_MSR_MASK to the boring value of
> 0xfffffffffffffffe, but presumably that'll change some day.

OK

>> +	mtsrr0	r10
>> +	mtsrr1	r11
>> +	rfid
>> +	b       .
>> +
>> +rtas_return_loc:
>> +	FIXUP_ENDIAN
>>  	ld	r0, 16(r1)
>>  	mtlr	r0
>>  	blr
>> -- 
>> 2.5.0
> 
> Thanks,
> drew
> 

Thanks,
Laurent