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

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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@xxxxxxxxxx>
> ---
>  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

> +    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=256 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.

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

Thanks,
drew
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