[PATCH] arm64: Enforce endianness build flags for LD and AS

[PATCH] arm64: Enforce endianness build flags for LD and AS

[Guenter Roeck]

If LD or AS is specified on the command line using "make LD=<my-ld>",
the endianness flag will not be added. Depending on the toolchain used,
this can result in endianness mismatch errors, such as

aarch64-cros-linux-gnu/binutils-bin/2.27.0/ld.bfd.real:
arch/arm64/crypto/.tmp_aes-ce-cipher.o:
	compiled for a big endian system and target is little endian

The problem was observed when using the Chrome OS build system (which sets
LD on the command line) for an arm64:allmodconfig build.

Use the override flag for both LD and AS to ensure that the endianness
flag is always set.

Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 arch/arm64/Makefile | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 939b310913cf..d780d00bea9c 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -56,15 +56,15 @@ KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
 ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
 KBUILD_CPPFLAGS	+= -mbig-endian
 CHECKFLAGS	+= -D__AARCH64EB__
-AS		+= -EB
-LD		+= -EB
+override AS		+= -EB
+override LD		+= -EB
 LDFLAGS		+= -maarch64linuxb
 UTS_MACHINE	:= aarch64_be
 else
 KBUILD_CPPFLAGS	+= -mlittle-endian
 CHECKFLAGS	+= -D__AARCH64EL__
-AS		+= -EL
-LD		+= -EL
+override AS		+= -EL
+override LD		+= -EL
 LDFLAGS		+= -maarch64linux
 UTS_MACHINE	:= aarch64
 endif
-- 
2.7.4

[PATCH] arm64: Enforce endianness build flags for LD and AS

[Doug Anderson]

Hi,

On Tue, Oct 3, 2017 at 1:58 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> If LD or AS is specified on the command line using "make LD=<my-ld>",
> the endianness flag will not be added. Depending on the toolchain used,
> this can result in endianness mismatch errors, such as
>
> aarch64-cros-linux-gnu/binutils-bin/2.27.0/ld.bfd.real:
> arch/arm64/crypto/.tmp_aes-ce-cipher.o:
>         compiled for a big endian system and target is little endian
>
> The problem was observed when using the Chrome OS build system (which sets
> LD on the command line) for an arm64:allmodconfig build.
>
> Use the override flag for both LD and AS to ensure that the endianness
> flag is always set.
>
> Cc: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  arch/arm64/Makefile | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

This seems right to me.  My understanding of the way things work is
that if you want a different linker or assembler you pass it on the
command line.  That means you need "override" like this if you want to
append to it.

As a self-proclaimed non-expert on the kernel build system I'm not
sure it's worth much, but in any case:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

[PATCH] arm64: Enforce endianness build flags for LD and AS

[Guenter Roeck]

On Tue, Oct 03, 2017 at 01:58:22PM -0700, Guenter Roeck wrote:
> If LD or AS is specified on the command line using "make LD=<my-ld>",
> the endianness flag will not be added. Depending on the toolchain used,
> this can result in endianness mismatch errors, such as
> 
> aarch64-cros-linux-gnu/binutils-bin/2.27.0/ld.bfd.real:
> arch/arm64/crypto/.tmp_aes-ce-cipher.o:
> 	compiled for a big endian system and target is little endian
> 
> The problem was observed when using the Chrome OS build system (which sets
> LD on the command line) for an arm64:allmodconfig build.
> 
> Use the override flag for both LD and AS to ensure that the endianness
> flag is always set.
> 
> Cc: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Please ignore this patch for now; it doesn't help with my problem. Not yet
sure what happens, but it appears that "-EB" doesn't make it into the LD
variable used by cmd_make_builtin in scripts/Makefile.build. I'll have
to figure out what is going on.

Thanks,
Guenter

> ---
>  arch/arm64/Makefile | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 939b310913cf..d780d00bea9c 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -56,15 +56,15 @@ KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
>  ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
>  KBUILD_CPPFLAGS	+= -mbig-endian
>  CHECKFLAGS	+= -D__AARCH64EB__
> -AS		+= -EB
> -LD		+= -EB
> +override AS		+= -EB
> +override LD		+= -EB
>  LDFLAGS		+= -maarch64linuxb
>  UTS_MACHINE	:= aarch64_be
>  else
>  KBUILD_CPPFLAGS	+= -mlittle-endian
>  CHECKFLAGS	+= -D__AARCH64EL__
> -AS		+= -EL
> -LD		+= -EL
> +override AS		+= -EL
> +override LD		+= -EL
>  LDFLAGS		+= -maarch64linux
>  UTS_MACHINE	:= aarch64
>  endif
> -- 
> 2.7.4
> 

[PATCH] arm64: Enforce endianness build flags for LD and AS

[Guenter Roeck]

On Wed, Oct 04, 2017 at 11:31:08AM -0700, Guenter Roeck wrote:
> On Tue, Oct 03, 2017 at 01:58:22PM -0700, Guenter Roeck wrote:
> > If LD or AS is specified on the command line using "make LD=<my-ld>",
> > the endianness flag will not be added. Depending on the toolchain used,
> > this can result in endianness mismatch errors, such as
> > 
> > aarch64-cros-linux-gnu/binutils-bin/2.27.0/ld.bfd.real:
> > arch/arm64/crypto/.tmp_aes-ce-cipher.o:
> > 	compiled for a big endian system and target is little endian
> > 
> > The problem was observed when using the Chrome OS build system (which sets
> > LD on the command line) for an arm64:allmodconfig build.
> > 
> > Use the override flag for both LD and AS to ensure that the endianness
> > flag is always set.
> > 
> > Cc: Douglas Anderson <dianders@chromium.org>
> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> 
> Please ignore this patch for now; it doesn't help with my problem. Not yet
> sure what happens, but it appears that "-EB" doesn't make it into the LD
> variable used by cmd_make_builtin in scripts/Makefile.build. I'll have
> to figure out what is going on.
> 
Yes, the problem is that the gcc in the Chrome OS toolchain doesn't tell
the linker which endianness to use (ie it doesn't translate -mbig-endian 
into a linker flag). Please forget this patch, it doesn't solve anything.
Sorry for the noise.

Guenter