linux-kernel - Re: [PATCH] arm: vdso: pass --be8 to linker if necessary

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Message-ID: <CAK7LNARFUaaJH+g3oGzwFyKnELum72nOzxnvUfMKYBaAoGVkug@mail.gmail.com>
Date:   Fri, 31 May 2019 11:01:23 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH] arm: vdso: pass --be8 to linker if necessary

Hi Jason,

Thanks for catching this.

On Thu, May 30, 2019 at 3:26 AM Jason A. Donenfeld <Jason@...c4.com> wrote:
>
> The commit fe00e50b2db8 ("ARM: 8858/1: vdso: use $(LD) instead of $(CC)
> to link VDSO") removed the passing of CFLAGS, since ld doesn't take
> those directly. However, prior, big-endian ARM was relying on gcc to
> translate its -mbe8 option into ld's --be8 option. Lacking this, ld


'git grep -- -mbe8' has no hit.

Is it a toolchain internal flag?



> generated be32 code, making the VDSO generate SIGILL when called by
> userspace.
>
> This commit passes --be8 if CONFIG_CPU_ENDIAN_BE8 is enabled.
>
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
> Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
> Cc: Russell King <rmk+kernel@...linux.org.uk>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> ---
>  arch/arm/vdso/Makefile | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
> index fadf554d9391..1f5ec9741e6d 100644
> --- a/arch/arm/vdso/Makefile
> +++ b/arch/arm/vdso/Makefile
> @@ -10,9 +10,10 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
>  ccflags-y := -fPIC -fno-common -fno-builtin -fno-stack-protector
>  ccflags-y += -DDISABLE_BRANCH_PROFILING
>
> -ldflags-y = -Bsymbolic --no-undefined -soname=linux-vdso.so.1 \
> +ldflags-$(CONFIG_CPU_ENDIAN_BE8) := --be8
> +ldflags-y := -Bsymbolic --no-undefined -soname=linux-vdso.so.1 \
>             -z max-page-size=4096 -z common-page-size=4096 \
> -           -nostdlib -shared \
> +           -nostdlib -shared $(ldflags-y) \
>             $(call ld-option, --hash-style=sysv) \
>             $(call ld-option, --build-id) \
>             -T
> --
> 2.21.0
>


--
Best Regards
Masahiro Yamada