Re: [PATCH 02/12] s390: don't build vdso32 with clang

Nick Desaulniers
2019-04-10T16:26:30Z

On Mon, Apr 8, 2019 at 2:27 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> clang does not support 31 bit object files on s390, so skip
> the 32-bit vdso here, and only build it when using gcc to compile
> the kernel.

What's the build failure? Would you mind filing a bug against LLVM's
issue tracker for it, please?

>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> arch/s390/Kconfig | 3 +++
> arch/s390/kernel/Makefile | 2 +-
> arch/s390/kernel/vdso.c | 10 +++++-----
> 3 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index b6e3d0653002..8cd860cba4d1 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -388,6 +388,9 @@ config COMPAT
> (and some other stuff like libraries and such) is needed for
> executing 31 bit applications. It is safe to say "Y".
>
> +config COMPAT_VDSO
> + def_bool COMPAT && !CC_IS_CLANG
> +
> config SYSVIPC_COMPAT
> def_bool y if COMPAT && SYSVIPC
>
> diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
> index 8a62c7f72e1b..1222db6d4ee9 100644
> --- a/arch/s390/kernel/Makefile
> +++ b/arch/s390/kernel/Makefile
> @@ -86,7 +86,7 @@ obj-$(CONFIG_TRACEPOINTS) += trace.o
>
> # vdso
> obj-y += vdso64/
> -obj-$(CONFIG_COMPAT) += vdso32/
> +obj-$(CONFIG_COMPAT_VDSO) += vdso32/
>
> chkbss := head64.o early_nobss.o
> include $(srctree)/arch/s390/scripts/Makefile.chkbss
> diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
> index e7920a68a12e..243d8b1185bf 100644
> --- a/arch/s390/kernel/vdso.c
> +++ b/arch/s390/kernel/vdso.c
> @@ -29,7 +29,7 @@
> #include <asm/vdso.h>
> #include <asm/facility.h>
>
> -#ifdef CONFIG_COMPAT
> +#ifdef CONFIG_COMPAT_VDSO
> extern char vdso32_start, vdso32_end;
> static void *vdso32_kbase = &vdso32_start;
> static unsigned int vdso32_pages;
> @@ -55,7 +55,7 @@ static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
>
> vdso_pagelist = vdso64_pagelist;
> vdso_pages = vdso64_pages;
> -#ifdef CONFIG_COMPAT
> +#ifdef CONFIG_COMPAT_VDSO
> if (vma->vm_mm->context.compat_mm) {
> vdso_pagelist = vdso32_pagelist;
> vdso_pages = vdso32_pages;
> @@ -76,7 +76,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
> unsigned long vdso_pages;
>
> vdso_pages = vdso64_pages;
> -#ifdef CONFIG_COMPAT
> +#ifdef CONFIG_COMPAT_VDSO
> if (vma->vm_mm->context.compat_mm)
> vdso_pages = vdso32_pages;
> #endif
> @@ -223,7 +223,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
> return 0;
>
> vdso_pages = vdso64_pages;
> -#ifdef CONFIG_COMPAT
> +#ifdef CONFIG_COMPAT_VDSO
> mm->context.compat_mm = is_compat_task();
> if (mm->context.compat_mm)
> vdso_pages = vdso32_pages;
> @@ -280,7 +280,7 @@ static int __init vdso_init(void)
> int i;
>
> vdso_init_data(vdso_data);
> -#ifdef CONFIG_COMPAT
> +#ifdef CONFIG_COMPAT_VDSO
> /* Calculate the size of the 32 bit vDSO */
> vdso32_pages = ((&vdso32_end - &vdso32_start
> + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
> --
> 2.20.0
>

--
Thanks,
~Nick Desaulniers